CENTER FOR NANOSCALE SCIENCE & TECHNOLOGY

2010

CENTER FOR NANOSCALE SCIENCE & TECHNOLOGY 2010
FROM THE DIRECTOR: THE END OF THE BEGINNING

The publication of this 2010 Report marks the “end of the beginning” of the Center for 

Nanoscale Science and Technology (CNST). As we conclude our third full year of operation, 

we have completed the recruitment of our permanent staff, are in the final stages of equipping 

their laboratories, and are completing the hiring of a cadre of very talented postdoctoral 

researchers to begin what we hope will be memorable starts to highly productive careers. 

Similarly, the NanoFab is adding the last few key items needed to provide the comprehensive 

tool set requested by our stakeholders, and has brought in the technical experts needed to 

run and maintain these tools. This Report updates the state of the CNST and highlights the 

2009-2010 accomplishments of the Center and its research participants.

As one of NIST’s two User Facilities, the CNST strives to make the measurement and 

fabrication tools needed to advance nanotechnology readily accessible to our stakeholders—

industry, academia, NIST, and other government agencies. These tools include both those 

that are commercially available, available through the shared NanoFab resource, and the 

next generation being developed by our research project leaders.

As a result of CNST’s growth in resources and capabilities over the past two years, we have 

seen a dramatic growth in our impact. During fiscal year 2010, the CNST had 970 researchers 

participating in projects using CNST resources, representing a 145 % growth over fiscal year 

2008. Participants represented 53 companies, 133 universities, 24 government institutions, 

and 39 states and the District of Columbia. Corporate researchers working in the NanoFab 

ranged from a small company, WCH technologies, started by an entrepreneurial inventor 

who needed the tools and expertise to turn his invention into a working prototype, to IBM, a 

Fortune 20 company utilizing our resources to reduce the development cycle time of future 

supercomputer technologies. NanoFab tool use increased by 90 % during the last year 

alone. The growth in research participation is beginning to be reflected in publications, with 

the number of participant publications growing by 40 % in the last year.

The CNST research staff is demonstrating major innovations in nanoscale measurement, 

including break-through advances characterizing the electronic structure of graphene, 

enabling sensitive spectroscopy on nanophotonic devices, and rapidly tracking and 

manipulating individual nanoparticles. The quality of their work is demonstrated by the 

substantial fraction of CNST staff publications that have appeared in high-impact journals, 

as well as by the professional honors and awards bestowed on the staff.

We appreciate your interest in the CNST and invite you to participate with us in the 

development of nanoscale science and technology by using our NanoFab or collaborating 

with one of our researcher staff members. You can keep abreast of such opportunities, our 

growing capabilities, and our most recent accomplishments by visiting us on the web at 

www.nist.gov/cnst.

Robert Celotta

December 31, 2010
From the Director: The End of the Beginning

The Center for Nanoscale Science and Technology in Brief................................................................................................................................................2.

FY2010 Resources..................................................................................................................................................................................................................2.

NanoFab Capabilities.............................................................................................................................................................................................................2.

Next Generation Measurement Research Focus Areas........................................................................................................................................................2.

CNST Organizational Groups.................................................................................................................................................................................................2.

Mission and Metrics .....................................................................................................................................................................................................................4.

CNST Overview......................................................................................................................................................................................................................4.

Reducing Measurement Barriers to Innovation ....................................................................................................................................................................6.

Key Metrics............................................................................................................................................................................................................................8.

Encouraging a Strong Safety Culture ..................................................................................................................................................................................10.

The NanoFab: A Shared National Resource...........................................................................................................................................................................12.

NanoFab Overview...............................................................................................................................................................................................................12.

Establishing a NanoFab Project...........................................................................................................................................................................................13.

NanoFab Costs.....................................................................................................................................................................................................................14.

NanoFab Operations............................................................................................................................................................................................................15.

NanoFab Capabilities: Tools and Processes........................................................................................................................................................................16.

CNST Research: Creating the Next Generation of Nanoscale Measurement Tools......................................................................................................20.

Electron Physics Group ........................................................................................................................................................................................................20.

Energy Research Group........................................................................................................................................................................................................28.

Nanofabrication Research Group ........................................................................................................................................................................................34.

Project Highlights ........................................................................................................................................................................................................................42.

Measuring Quantum Electronic Properties of Graphene ....................................................................................................................................................42.

Localization in Graphene Devices Probed by STM .............................................................................................................................................................43.

Development of Si-Based Single-Electron Devices (SEDs) for a Fundamental Current Standard and for Quantum Information ....................................44.

Laser Direct Write to Enhance Inter-Chip IO Bandwidth ....................................................................................................................................................45.

Measurement of Current Polarization by Doppler-Shifted Spin Waves.............................................................................................................................46.

The Effect of Disorder on Magnetic Dynamics...................................................................................................................................................................48.

Ultra-High-Density Patterned Magnetic Recording Media.................................................................................................................................................49.

Magnetic Nanopillars Fabricated Using Electron Beam Lithography.................................................................................................................................50.

Imaging 3D Magnetic Nanostructure in Ferromagnetic Multilayers..................................................................................................................................51.

Measuring Light-Matter Interactions in Chip-Based Optical Cavities...............................................................................................................................52.

Probing Plasmonic-Photonic Interactions in Periodic Nanowire Arrays.............................................................................................................................53.

Efficiency Enhancement of Copper Contaminated Radial p-n Junction Solar Cells..........................................................................................................55.

Nanoscale Characterization of Organic Photovoltaic Devices............................................................................................................................................56.

Self-Assembly of Lithographically Patterned Cubic Nanostructures.................................................................................................................................57.

Line-Edge Roughness Measurements in Diblock Copolymers...........................................................................................................................................58.

The Effect of Resist on the Transfer of Line-Edge Roughness Spatial Metrics from Mask to Wafer...............................................................................59.

Measurement Platforms to Facilitate Nanoimprint Lithography........................................................................................................................................60.

Novel Sources for Focused Ion Beams................................................................................................................................................................................61.

In Situ Measurements of Thermodynamics and Reaction Kinetics During Nanomaterials Synthesis and Catalysis.......................................................62.

Particle-Tracking Measurements of Nanoparticle Dynamics in Fluids...............................................................................................................................63.

Atomic-Scale Silicon Surface Control to Enable Atom-Based Dimensional Metrology....................................................................................................64.

Nanoscale Linewidth Standards for AFM Calibration ........................................................................................................................................................65.

Developing Nanocalorimetry Techniques and Material Standards for Measuring Properties of Exothermic Reactions in Multilayer Films..................66.

Microfluidic Bumping Chip for Purification of Tumor Cells from Blood ..............................................................................................................................67.

Neural Probes with Waveguides and a Fiber-Coupled Light Emitting Diode.....................................................................................................................68.

Personnel Highlights...................................................................................................................................................................................................................70.

New Project Leaders and NanoFab Staff............................................................................................................................................................................70.

Visiting Fellows....................................................................................................................................................................................................................72.

Postdoctoral Researchers....................................................................................................................................................................................................73.

Student Researchers and Summer Undergraduate Research Fellows...............................................................................................................................74.

CNST Staff Honors and Awards ................................................................................................................................................................................................76.

Research Participant Publications ..........................................................................................................................................................................................78.

CNST Staff Publications (FY2009–FY2011:Q1) ...................................................................................................................................................................78.

Other Research Participant Publications (FY2009–FY2010) ...............................................................................................................................................81

Table of Contents
2 | CNST

The Center for Nanoscale Science 

and Technology in Brief

The Center for Nanoscale Science and Technology (CNST) supports 

the U.S. nanotechnology enterprise from discovery to production by 

providing industry, academia, NIST, and other government agencies 

with access to world-class nanoscale measurement and fabrication 

methods and technology. The CNST is the only national nanocenter with 

a focus on commerce.

The  CNST’s  shared NanoFab resource gives researchers economical 

access to and training on a state-of-the-art, commercial tool set required 

for cutting-edge nanotechnology development. The simple application 

process is designed to get projects started in a few weeks.

Looking beyond the current state of the art, CNST research is creating 

the next generation of nanoscale measurement instruments and 

methods, which are made available through collaboration.

As the Department of Commerce nanocenter, the CNST provides:

•	 A unique user facility offering access to the instrumentation, 

methods, and technical expertise required to make and measure 

components at the nanometer scale;

•	 A world-class, shared resource for nanoscale measurement and 

fabrication widely accessible to researchers from both inside and 

outside NIST;

•	 Expertise in a wide variety of disciplines, including physics, 

chemistry, materials science, molecular biology, computer 

science, and electrical, mechanical, chemical, and aeronautical 

engineering; and

•	 A hub linking the international nanotechnology community to the 

comprehensive related measurement expertise throughout NIST.

F Y 20 1 0 RESOURCES

$23 million annual budget

97 staff (87 technical)

NANOFAB CAPABILITIES

•	 Over 5600 m2 (60,000 square feet) of laboratory space, including 

a 1,800 m2 (19,000 square foot) cleanroom, with 750 m2 (8,000 

square feet) at class 100

•	 Over 65 major commercial measurement and processing tools in 

the cleanroom, including electron beam-, photo- and nanoimprintlithography, laser writing and mask generation, field emission 

scanning electron microscopy, metal deposition, plasma etching, 

chemical vapor deposition, atomic layer deposition, and silicon 

nano/micromachining.

MISSION AND METRICS

•	 Additional tools outside the cleanroom, including a 

transmission electron microscope, multiple focused ion 

beam systems, and an atomic force microscope.

N E X T G E N E R A T I O N M E A S U R E M E N T 

RESEARCH FOCUS AREAS

•	 Future Electronics

•	 Nanomanufacturing

•	 Energy Transport, Storage, and Conversion

CNST ORGANIZATIONAL GROUPS

•	 Electron Physics

•	 Energy

•	 NanoFab Operations

•	 Nanofabrication Research
2010 | 3

Center for Nanoscale Science 

and Technology 

Robert Celotta, Director

Lloyd Whitman, Deputy Director

Joyce Waters, Executive Assistant

LaDonna Lauren, Senior Management Advisor

Robert Rudnitsky, Scientific Advisor

Russell Hajdaj, Safety Officer 

Karen Haugh, Administrative Officer

Denise Rogers, Information Manager

Electron Physics Group

Jabez McClelland, Group Leader

Teresa Figgs, Admin. Asst.

Nanofabrication 

Research Group

J. Alexander Liddle, 

Group Leader

Yeehing Lam, Admin. Asst

Energy Research Group

Nikolai Zhitenev, Group Leader

Amanda Dyson, Admin. Asst. 

NanoFab Operations Group

Vincent Luciani, NanoFab Manager

Matthew Gonzales, Admin. Asst.

Wade Hall, User Coordinator

Jeff Pasternak, User Coordinator
Mission and Metrics 

CNST OVERVIEW

The CNST was established in May of 2007 as a unique national facility 

purposely designed to accelerate innovation in nanotechnology-based 

commerce. Its mission is to operate a national, shared  resource  for 

nanoscale fabrication and measurement and develop innovative 

nanoscale measurement and fabrication capabilities to support 

researchers from industry, academia, NIST, and other government 

agencies in advancing nanoscale technology from discovery to 

production. The Center, located in the Advanced Measurement 

Laboratory Complex on NIST’s Gaithersburg, MD campus, disseminates 

new nanoscale measurement methods by incorporating them into 

facility operations, collaborating and partnering with others, and 

providing international leadership in nanotechnology.

In the few years since its inception, the CNST has become a major 

national resource for nanoscale science and the development of 

nanotechnology, and the only national nanocenter with a focus 

on commerce. Unique in its mission to provide the measurement 

infrastructure that underlies all progress in this critically important 21st 

century technology, the CNST serves the U.S. industrial and scientific 

research communities by providing a venue for highly collaborative, 

multidisciplinary research, supported by direct access to the required 

state-of-the-art tools. The continued development of nanotechnology 

is crucial to firmly establishing U.S. leadership in such diverse fields 

as energy, manufacturing, information technology, electronics, health, 

and biotechnology. In the case of energy, nanoscale phenomena lie at 

the heart of a great many energy production, storage, and transmission 

processes. Research aimed at optimizing the nanoscale structure 

of photovoltaic or solar-thermal devices can, for example, have a 

profound impact by enhancing the conversion of the sun’s energy to 

electricity. Such research demands a multidisciplinary approach and 

the development and ready availability of advanced tools capable of 

manipulating and measuring the properties of structures at sizes that 

can be counted in atoms.

The CNST has been purposely built to uniquely satisfy these demands. 

Offering many unique measurement capabilities, it provides a 

collaborative, multidisciplinary research environment focused on national 

nanoscale measurement needs in such areas as next-generation energy 

systems, future electronics, nanofabrication, and nanomanufacturing. In 

this environment, innovative research is advancing the state-of-the-art 

of nanoscale measurement and fabrication. A critical component of the 

CNST, the NanoFab, offers open, convenient, and economical access to 

a comprehensive suite of state-of-the-commercial-art fabrication tools, 

measurement tools, and processes. The NanoFab is uniquely designed 

to support both new ventures that require hands-on assistance and 

training, and experienced practitioners needing access to a reliable and 

professionally-run research “fab” with a broad selection of advanced, 

MISSION AND METRICS

4 | CNST

well maintained tools. Quick access (a few weeks) is available 

through a simple, merit-based application process. Proprietary 

research can also be performed.

Having now completed its initial ramp up in staff, equipment, 

facilities, and processes, the CNST is continuing to expand on 

its strategic relationships and collaborations with industrial 

and academic partners. As reported in more detail below, in 

FY2010 nearly 1000 researchers participated in CNST-supported 

projects, affiliated with 53 companies, 24 government institutions, 

133 universities, and coming from 39 states and the District of 

Columbia.
2010 | 5

192

524

396

970

2007 2008 2009 2010 0

200

400

600

800

1000

 

1200

RESEARCH PARTICIPANT GROWTH

R E S E A R C H P A R T I C I P A N T A F F I L I A T I O N S B Y 

FISCAL YEAR

Affiliation 2008 2009 2010

Academia 169 (43 %) 216 (41 %) 439 (45 %)

NIST 163 (41 %) 198 (38 %) 311 (32 %)

Other Government 46 (12 %) 55 (10 %) 105 (11 %)

Industry 18 (5 %) 55 (10 %) 115 (12 %)

Total 396 (100 %) 524 (100 %) 970 (100 %)

FISCAL YEAR

NUMBER OF RESEARCH PARTICIPANTS

The number of Research Participants is considered 

the principal metric for the NIST User Facilities, as 

it is the most direct measure of the extent that our 

stakeholders are benefiting from these facilities.
R E D U C I N G M E A S U R E M E N T B A R R I E R S 

T O I N N O V A T I O N 

The organization of the CNST is designed to meet several important 

goals. To support our central mission, our design must logically support 

both safe and efficient access to a large tool set and have a significant 

research capability aimed at furthering the state-of-the-art. We aim to 

satisfy the first objective through a shared resource, the NanoFab, that 

operates much like a nanofabrication facility found within the National 

Nanotechnology Infrastructure Network supported by the National 

Science Foundation. The cost of maintaining and operating the tools is 

recovered by charging an hourly rate for tool use that varies depending 

upon the tool. Users doing proprietary research pay the full cost 

recovery rate. Otherwise, users supporting the mission of the CNST 

may qualify for a reduced rate that substantially lowers their charges. 

We pay the balance of the costs into the NanoFab account from the 

CNST appropriated research budget. No distinction is made between 

academia, business, or government in determining the applicability 

for the reduced rate; the rate is determined by what you are doing, 

not where you are from. The equitable access policies, especially as 

applied to industrial researchers, make the CNST a valued resource 

among nanocenters.

Another goal is to reduce the barriers to using the NanoFab to an absolute 

minimum. This goal is particularly important because companies, most 

notably small companies, frequently need rapid access to tools and 

expertise. Further, many of their needs would not be ranked highly if 

held to a standard of cutting edge fundamental science in a peer review 

process. Hence, our entry process uses very simple applications that 

are reviewed by CNST staff, on a continuous basis throughout the year, 

for safety, appropriateness, and merit. Typically, only a week or two is 

required to obtain access; tool use is then on a first come, first served 

basis via an on-line reservation system.

Researchers working in the NanoFab possess a broad spectrum of 

knowledge and experience, ranging from seasoned veterans with 30 

years of experience to complete novices. The veterans are granted 

access relatively quickly following a mandatory safety course and 

examination, and confirmation by our NanoFab staff that they are fully 

qualified to operate the tools they need. This option is popular with 

some companies because, if no NanoFab staff members are involved, 

the company will retain sole ownership of any intellectual property 

created during that work. At the other extreme, complete novices may 

choose to be trained on the tools they need to use, have a NanoFab 

staff member run the process for them, or employ a combination of both 

alternatives. An initial project discussion with the NanoFab staff and 

a relevant expert from the research staff helps determine the optimal 

processing steps. Because many NanoFab researchers will depend 

on our staff for extensive consultation and help, we have staffed the 

NanoFab with highly experienced process engineers drawn largely 

MISSION AND METRICS

6 | CNST

Academia

439

NIST

311

Industry

115 Other 

Government

105

20 1 0 R E S E A R C H P A R T I C I P A N T 

AFFILIATIONS
2010 | 7

from the semiconductor industry. Having an experienced staff is also 

important to maintaining stable and reliable processes in the NanoFab. 

A small company that has developed a process for making its own 

structures or device needs to be able to return several months later and 

be able to duplicate their prior results without having to start a new 

research project.

The development of measurements and fabrication methods that go 

well beyond the current commercial state-of-the-art requires a very 

different approach. For example, because nanotechnology is a young 

discipline that is rapidly evolving, it is important that our research 

approach be agile, allowing it to retarget its research and development 

objectives relatively quickly in response to perceived need. This need 

is best met by a relatively flat organizational structure, one that utilizes 

a multidisciplinary team of core researchers supplemented by a much 

larger cadre of postdoctoral researchers and a dedicated technical 

support staff. The frequent arrival of new postdoctoral researchers 

brings with it new knowledge, experience, and ideas as well as allowing 

much more rapid changes in direction than might otherwise be possible.

Researchers from outside the CNST can access the advanced tools 

under development through collaboration: either to aid in their 

development or to make early measurements using a tool or method 

not yet available elsewhere. Collaborators include visiting professors, 

industrial researchers, postdoctoral researchers, graduate students, 

or undergraduates, with tenures ranging from several days to several 

years. Even local high school students have successfully participated in 

CNST projects. Such collaborations are arranged by direct application 

to the leader of the research project of interest. In addition, formal 

strategic partnerships have been established. The CNST benefits 

greatly by the partnerships it has established with other programs.

Nanotechnology being such a broad topic, it is necessary to select 

carefully from a constantly changing list of priorities for new instrument 

and method development. One must have taken care, however, to 

assemble a research staff possessing a broad range of technical 

expertise and experience in order to maximize the number of tractable 

problems. For this reason, the CNST has selected experts in a several 

key nanotechnology fields. Currently, three priority research areas have 

emerged, based on a gap analysis of nanotechnology measurement 

needs: future electronics; nanomanufacturing; and nano-enabled 

energy conversion, storage, and transport devices.

20 1 0 INSTITUTIONS REPRESENTED

Academia 133

NIST 1

Other Government 23

Industry 53

Total 210
CNST Measurement Research Staff Expertise

Atomic-scale characterization and manipulation | Joseph Stroscio

Electro-fluidic control of nanoparticles | Benjamin Shapiro

Environmental transmission electron microscopy | Renu Sharma

Fluctuations and nanoscale control | Andrew Berglund

Laser-atom manipulation | Jabez McClelland

Modeling and simulation of nanofabrication | Gregg Gallatin

Nanofabrication and nanomanufacturing | J. Alexander Liddle

Nanomagnetic dynamics | Robert McMichael

Nanomagnetic imaging | John Unguris

Nanomaterials for energy storage and conversion | A. Alec Talin

Nanomaterials for solar fuels and artificial photosynthesis |

Veronika Szalai

Nanophotonics | Kartik Srinivasan

Nanoplasmonics | Henri Lezec

Nanoscale electronic and ionic transport | Nikolai Zhitenev

Nanotribology and nanomanufacturing | Rachel Cannara

Optical nanoelectromechanical systems | Vladimir Aksyuk

Theory, modeling, and simulation of nanostructures | Mark Stiles

Theory and modeling of nanomaterials for renewable energy | 

Paul Haney

Thermoelectrics and photovoltaics | Fred Sharifi

Vibrational spectroscopy and microscopy | Andrea Centrone 

KEY METRICS

Over the past two years, we have made major progress in our ability 

to track key metrics related to the use and impact of CNST resources. 

This progress results from the development of three databases and 

associated reporting systems: a comprehensive project management 

database; a publication and presentation database; and a suite of 

software tools for managing NanoFab tool usage and accounting.

The project management database, developed specifically for the 

CNST, is designed to track all CNST-supported projects, the researchers 

working on each project, and the outputs of each project, including 

NanoFab projects, CNST staff research projects, and a handful of 

projects supported extramurally by CNST grants. The database includes 

detailed technical and administrative information about each project, 

MISSION AND METRICS

8 | CNST

plus full affiliation and contact information for every research 

participant. A “Research Participant” is defined as anyone directly 

involved in a project performed in part at the CNST or through CNST 

financial support; i.e., someone that would be listed as a coauthor 

of an associated publication, presentation, patent application, etc. 

The number of Research Participants is considered the principal 

metric for the NIST User Facilities, as it is the most direct measure 

of the extent that industry, academia, NIST, and other government 

agencies are benefiting from these facilities.
2010 | 9

Publications are a trailing indicator of the impact of research, typically 

reflecting accomplishments in the prior year or two; a complete 

list of publications in FY2009 and FY2010 is included later in this 

Report. Although it is still too soon to analyze the impact of this 

work (e.g., through citation analyses), the year-over-year growth of 

CNST publications and their quality bodes well for the future, with 

approximately a quarter of our staff publications each year appearing 

in high-impact and letters journals.

The third data set we are collecting, from the NanoFab, is extracted 

from the CORAL suite of software tools (Common Object Representation 

for Advanced Laboratories) developed at the Stanford Nanofabrication 

Facility. This suite includes software for scheduling tool use, enabling 

the access of individual tools on a user-by-user basis (i.e., after training 

is completed), tracking tool usage time, and billing for each tool usage. 

20 1 0 G E O G R A P H I C D I S T R I B U T I O N O F 

RESEARCH PARTICIPANTS

WA M

MT ND E

OR MN VT NH

ID SD WI M NY MA

WY I RI

IA PA CT

CA NV NE NJ OH

IL IN DE UT

CO WV

KS MO VA MD

KY

NC TN

AZ OK 

NM AR SC

MS AL

GA Research 

TX

AK LA Participants

1 - 10 FL

11 - 20

HI

21 - 30

31 - 50

51 - 100

>100

“

“

I had a great visit to NIST, and I was able to quickly 

develop a process for our samples. This was greatly 

facilitated by the fact that I was able to leverage 

previous developmental work that had been performed 

at NIST. I was very impressed with your cleanroom 

facilities, the support provided by your staff, and the 

orientation process (safety classes, tours). Lee Oesterling

 Electronics, Sensors, & Information Systems

Battelle Memorial Institute
Over the past year most tools were interlocked with the CORAL system, 

with others in the process of being added. A dashboard is being 

developed, expected to be fully operational in FY2011, which will 

enable enhanced analyses of tool usage, helping us to better optimize 

the delivery of services to our NanoFab customers. Preliminary analysis 

indicates that overall use of the NanoFab grew by approximately 80 % 

in FY2010 over FY2009.

E N C O U R A G I N G A S T R O N G 

SAFETY CULTURE

The CNST strives to provide a safe place to work for our staff and 

visiting researchers, including those using the NanoFab. We have 

established extensive policies and procedures with the goal of ensuring 

an open and supportive work environment where all staff members are 

knowledgeable about Environment, Safety, & Health (ES&H) policies 

and practices and feel free to report any issues or concerns to the CNST 

management. We are proud that our safety program was recognized 

by the recent Final Report of the NIST Blue Ribbon Commission on 

Management and Safety II, which noted “The Center for Nanoscale 

Science and Technology (CNST) has an extensive set of rules and 

procedures for those who work in their facilities... NIST should adopt/

adapt these types of policies and procedures for the entire organization.”

 The main elements of our safety program are as follows:

Defining roles and responsibilities. We assign clear safety 

roles, responsibilities, accountabilities, and authorities essential to 

creating and maintaining a safe working environment; for example, 

each Project Leader is responsible for ensuring that nobody works 

in his/her lab without the education and training required and 

specified in the laboratory manual and hazard analyses.

Providing training required to work safely. All technical staff 

must complete a suite of on-line training modules before starting 

work in any laboratory. This basic training, typically completed 

by one’s second or third day at NIST, is supplemented by specific, 

hands-on training on the instrumentation within each laboratory, 

as specified in each laboratory’s manual and hazard analysis.

Before working in the NanoFab, every researcher must complete 

NanoFab safety training and orientation and pass a safety exam, 

with annual retesting required to maintain NanoFab access. 

NanoFab tools are individually interlocked to insure that a 

researcher can only access tools that he or she has been trained 

on and is authorized to use.

MISSION AND METRICS

1 0 | CNST

Performing comprehensive hazard analysis and control 

for all workplace activities. A comprehensive analysis 

must be completed, including multiple levels of management 

review, before any new work begins. During this process 

potential hazards are identified, a detailed analysis of the 

hazards and worst-case scenarios is performed, and detailed 

operating procedures, emergency plans, and required 

controls are developed, documented, and implemented. 

For laboratory activities involving nanoparticles, the CNST 

follows best practices as suggested by the National Institute 

for Occupational Safety and Health (NIOSH). In a bin outside 

every laboratory there is a laboratory manual that includes an 

authorized access list, personal protective equipment (PPE) 

guidance, and hazard assessment and control documentation. 
2010 | 1 1

Each bin also holds a notebook containing the appropriate Material 

Safety Data Sheets. Within the NanoFab, in addition to the tool-by-tool 

analyses performed as part of the CNST-wide process, the safety of 

each proposed project is assessed during the technical review.

Conducting management observations and inspections. The 

NanoFab is monitored at all times via an extensive closed-circuit video 

monitoring system by either the NanoFab staff or the NIST Emergency 

Services Division. All CNST managers are responsible for recognizing 

good safety practices, identifying potential safety improvements, and 

reporting these to a Center safety email distribution list. All NanoFab 

laboratories are inspected daily for safety and housekeeping problems, 

with all other laboratories inspected weekly by the designated manager 

of each space. In addition, each Group Leader conducts a quarterly 

safety inspection of all space using a standard checklist, and the Center 

Safety Representative follows up on outstanding issues. Finally, the 

Director, Deputy Director, and Group Leaders conduct an annual, allspace safety inspection.

Encouraging communication and a culture of safe work 

practices. Laboratory safety is considered everyone’s responsibility in 

the CNST, and all staff and researcher participants are expected to help 

enforce the rules throughout all laboratories. To promote this culture, 

the CNST has a dedicated, full-time Center Safety Representative 

who, among other responsibilities, oversees all chemical purchases, 

including ordering, delivery, and labeling through a centralized chemical 

receiving room. The CNST Director makes weekly laboratory visits to 

learn about research activities, with a safety conversation an integral 

part of each visit.

‘‘

‘‘The CNST has an extensive set of rules 

and procedures for those who work in 

their facilities... NIST should adopt/

adapt these types of policies and 

procedures for the entire organization. 

NIST Blue Ribbon Commission on Management and Safety II
The NanoFab: A Shared National Resource

NANOFAB OVERVIEW

The NanoFab provides access to state-of-the-art, commercial 

nanoscale measurement and fabrication tools and methods, along with 

associated technical expertise, to industry, academia, NIST, and other 

government agencies in a shared-access, shared-cost environment. It 

enables processing and characterization of a wide range of nanoscale 

materials, structures, and devices critical to the nation’s measurement 

and technology needs. The NanoFab also fosters internal collaboration 

in nanotechnology across NIST’s laboratories and external collaboration 

with NIST’s partners through its shared environment.

The NanoFab has the following key attributes:

•	 Rapid Access. The streamlined application process is designed 

to get projects started in a few weeks. 

•	 Extensive Process Support and Development. The NanoFab 

is operated by a professional staff of process engineers and 

technicians with over 240 years of collective experience. The 

NanoFab offers a broad catalogue of established processes, 

along with assistance in the development of new processes.

•	 Training and Education. The customer-oriented NanoFab staff 

members are available for expert consultation and hands-on 

training for all tools and processes.

•	 Shared Expertise. As a shared national resource open to 

all, the NanoFab brings NIST scientists together with industry, 

government, and academic researchers from across the spectrum 

of nanotechnology applications, enabling the rapid exchange of 

ideas and best practices.

•	 No Inherent Claims on Intellectual Property Rights. The 

CNST does not claim any rights to intellectual property used or 

developed in the NanoFab, unless a CNST federal employee is a 

co-inventor.

The NanoFab consists of a large clean room and several more 

specialized laboratory modules in an adjacent building. The NanoFab 

cleanroom occupies 1,800 m2 (19,000 square feet) of floor area, which 

includes 750 m2 (8,000 square feet) of class-100 space. The NanoFab 

cleanroom contains over 65 fabrication and processing tools, providing 

electron beam-, photo- and nanoimprint-lithography, laser writing and 

mask generation, an i-line stepper, field emission scanning electron 

microscopy (SEM), metal deposition, plasma etching, chemical vapor 

deposition, atomic layer deposition, and silicon micro/nano-machining. 

Additional tools, which are located outside the cleanroom, include three 

dual beam focused ion beam systems, an atomic force microscope, and 

a Titan 80-300 keV analytical transmission electron microscope (TEM) 

system with both X-ray and electron energy loss analytical capabilities. 

The CNST has a particularly strong capability in electron beam 

lithography. An ultra high resolution electron beam lithography system 

THE NANOFAB

1 2 | CNST

provides for direct write nanoscale feature development and mask 

writing capability from small samples up to 300 mm-diameter 

wafers. A second electron beam lithography tool is designed for 

direct writing with a 3 nm spot size on substrates up to 150 mm 

x 190 mm in size. For less demanding lithography tasks, a SEMbased electron beam writing tool is also available. Additionally, 

a state-of-the-art nano-imprint lithography system can produce 

nanoscale features in soft materials using a hard mask made 

with the electron beam writer. These tools are interlocked and 

controlled using CORAL.

The NanoFab is staffed and 

open from 7 a.m. to midnight, 

Monday through Friday.
2010 | 1 3

The NanoFab is staffed and open from 7 am to midnight, Monday 

through Friday, subject to NIST campus access requirements. Access 

hours for researchers from outside NIST depends on a variety of factors, 

including citizenship and the length and frequency of anticipated visits 

to the NanoFab, but the NanoFab Manager works with each researcher 

to ensure that all work can be scheduled during permitted access times. 

For researchers with out-of-hours access to the campus, the NanoFab 

is available at all times, seven days a week, subject to the approval of 

the NanoFab Manager and with a requirement that work be done under 

the buddy system, with at least two researchers present at all times.

E S T A B L I S H I N G A N A N O F A B P R O J E C T 

Someone interested in starting a project at the NanoFab is strongly 

encouraged to begin by discussing the project with the NanoFab 

Manager. If the project leader is new to nanoscale measurement 

or fabrication, the NanoFab Manager first discusses possible ways 

to make or measure the project’s nanoscale components. For a 

researcher experienced in the field, the Manager discusses what tools 

and processes are available to meet the project’s needs. Indeed, the 

prospective project may well benefit by the processes or know how 

developed by other NanoFab projects. The NanoFab Manager also 

provides an overview of the application process and payment options, 

along with the orientation and training requirements. When someone 

is ready to begin the new project, the project leader fills out a Project 

Application and returns it to the Facility User office, where the applicant 

is guided through the rest of the process.

Each project application is assessed by a Technical Review Committee 

comprised of NIST experts in nanoscale measurement and fabrication. 

The project is reviewed to ensure it can be performed safely in 

the NanoFab, that it will not compromise the use of any tools (e.g., 

by contamination), that it will not unduly prevent others from using 

necessary tools, and that it is feasible with the available resources. 

Finally, it is assessed as to the merit of the overall goal of the project, 

in order to prioritize projects in the event that needed resources are 

oversubscribed.

The project application process averages about two weeks from 

application submission to project approval, at which point an initial 

payment must be made and an orientation session scheduled. There 

are a number of factors that affect how quickly someone can come to 

NIST and get started in the NanoFab. First, we review applications 

every Tuesday; therefore, if an application is submitted by 5 p.m. on a 

Monday, it will be reviewed that week. Second, as soon as possible, 

an applicant should discuss with his or her organization and one of the 

NanoFab Facility User Coordinators the most efficient way to transfer to 

the NanoFab funds sufficient to cover the estimated cost of the project. 

Finally, each researcher planning to work in the NanoFab will need to 

be cleared by NIST Security to access the NIST campus and NanoFab 

laboratories. If a researcher already has a NIST badge as an employee 

or Guest Researcher, there are no additional access requirements. For 

a U.S. citizen or Permanent Resident, a badge providing access can be 

issued within a few days of project approval. For a foreign national, 

it may take at least an additional 30 days to be approved for a badge. 

However, during that time we can usually arrange for a one or two day 
visit to complete orientation and some initial training in order to help 

the researcher get started as quickly as possible.

New NanoFab researchers are required to complete three levels of 

training to begin working independently in the NanoFab, as follows:

1. Basic orientation covers operations and safety protocols for 

use of the NanoFab. The class is a two hour, hands-on training 

session given at the CNST every Monday morning. Attendance 

can be scheduled through the NanoFab Facility User office.

2. New researchers must also pass a comprehensive safety exam. 

The on-line exam takes about 30 minutes and can be scheduled 

through the NanoFab Facility User office any time after completion 

of the basic orientation.

3. New researchers are also required to have specific tool training

to be certified on each piece of NanoFab equipment their 

work requires. Tool certification sessions can be scheduled by 

contacting the primary or secondary owner of the tool you wish to 

use. Note that a CORAL account is required for tool certification. 

NANOFAB COSTS

There are three types of hourly rates charged to every NanoFab 

researcher to recover the costs of performing the work: Specific Tool Use, 

Cleanroom Use, and Process Assistance (when applicable). Each rate is 

computed for full cost recovery, including the cost of the NanoFab staff 

time required plus the operating costs. The operating costs include the 

costs of any maintenance contracts, routine maintenance and repairs 

(both scheduled and unscheduled), and accessories and consumable 

supplies. After a full cost recovery rate is computed, for projects that 

advance the CNST mission, a reduced cost percentage is applied to 

compute the reduced rates charged to those projects. The eligibility 

criteria for reduced rates are discussed below. As a matter of NIST 

policy, proprietary projects are not eligible for the lower rates and must 

pay the full cost for work performed in the NanoFab. The charges for 

every NanoFab project are based on the same rates, including projects 

led by NIST employees (CNST research staff included).

NIST requires an initial funding authorization that is sufficient to cover 

the estimated charges for each new project. However, researchers are 

only billed for the actual charges incurred. The NanoFab operates on a 

monthly billing cycle and provides reports of each project’s tool usage 

and costs at the close of each cycle. The NanoFab accepts payment 

by a variety of methods, including credit card and purchase order. The 

NanoFab Manager typically works with new applicants during the initial 

application process to estimate the expected charges for each project.

THE NANOFAB

1 4 | CNST

Non-proprietary projects may be eligible for reduced rates, with 

the balance of the full cost paid by the CNST from its appropriated 

research budget. All applicants, including those from NIST, can 

request consideration during the application process, and the 

project will be rated on the extent that it contributes to the CNST 

mission by developing and/or applying nanoscale measurement 

and fabrication methods to further the development of 

nanotechnology. All such requests are decided on a case by case 

basis, typically within 10 days of an application being submitted, 

following review by a CNST committee and final approval by the 

CNST Director.
2010 | 1 5

NANOFAB OPERATIONS

The NanoFab is operated by a team of experienced engineers and 

technicians dedicated to customer service, with two process engineers 

remaining on site on weekday evenings until midnight. The team is 

focused on supporting the researchers working in the NanoFab by 

running the tools and establishing consistent baseline processes. The 

staff also develops new processes in response to researcher needs. 

Members of the CNST research staff also apply their expertise to help 

evaluate and consult on NanoFab projects. 

Effective communication between our research participants and the 

NanoFab staff is essential to NanoFab operations. In addition to 

periodic informational meetings to which all NanoFab researchers are 

invited, we maintain a standing NanoFab Researcher Committee. This 

committee is composed of two representatives from each of the four 

NIST Laboratories, a representative from the NIST Center for Neutron 

Research, an external NanoFab researcher, a representative from the 

NanoFab Facility User office, and the NanoFab Manager. The committee 

Chair rotates annually among the members. The committee helps keep 

the Manager informed about general issues in the NanoFab, including 

the impact of operating policies and procedures, training needs, tool 

maintenance, new tool requests, and the general level of satisfaction 

among the NanoFab research community. The Committee also provides 

a useful conduit for information from the NanoFab back to the research 

community.

NanoFab Operations Group

December 2010

Vincent Luciani | NanoFab Manager 

Matthew Gonzales | Administrative Assistant

Wade Hall | Facility User Coordinator

Jeff Pasternak | Facility User Coordinator

Process Engineers and Technicians

Jerry Bowser 

Laurence Buck 

Marc Cangemi 

Lei Chen 

Justin Dickinson 

Gerard Henein

Michael Hernandez

Richard Kasica

Chester Knurek

Alline Myers

Eileen Sparks

William Young

The charges for every NanoFab project 

are based on the same rates, including 

projects led by NIST staff members. 
[NanoFab	
  –	
  Lithography)	
  

The	
  advanced	
  lithography	
  capabili9es	
  in	
  the	
  NanoFab	
  are	
  demonstrated	
  by	
  this	
  silicon	
  

structure,	
  where	
  three	
  separate	
  layers	
  of	
  nanoscale	
  lithography	
  have	
  been	
  implemente

overlay	
  accuracy	
  ≤	
  20	
  nm.	
  	
  Courtesy	
  of	
  Neil	
  Zimmerman,	
  NIST

100 nm 

N A N O F A B C A P A B I L I T I E S : 

T O O L S A N D P R O C E S S E S 

NanoFab researchers will find the tools well maintained and fully 

operational, with standard processes well under control. Statistical 

Process Control charts and standard processes are used to measure 

and control tool performance. All standard processes are documented 

for easy reference by users, and new processes are constantly being 

developed. The NanoFab community also benefits from the many 

processes developed by non-proprietary projects that are made 

available to everyone. The NanoFab provides a standard recipe 

template and encourages all researchers who develop a useful new 

process to document it for use by others.

The NanoFab is equipped with a comprehensive set of nanofabrication 

and analytical tools. The toolset is generally equipped to handle wafer 

sizes up to 150 mm in diameter, including small and irregularly-shaped 

samples. Many of the tools can handle 200 mm-diameter wafers. A 

complete list of the toolset is available at the NanoFab web site. An 

overview of the key capabilities associated with the NanoFab’s major 

tools and processes is provided below, including major new capabilities 

added in the past two years and those to be installed in 2011.

Lithography—The NanoFab has extensive lithographic capabilities 

and more on the way, including two full time electron beam lithography 

systems; a SEM based electron beam writer; nano-imprint lithography; 

a laser writer for mask or direct write lithography; and two i-line contact 

aligners. Most standard resists, both positive and negative, and their 

associated developers are readily available. Ancillary equipment, such 

as hexamethyldisilazane (HMDS) primers, a critical dimension (CD) 

measurement tool, and spin coaters is also available.

The advanced lithography capabilities in the NanoFab are demonstrated by this 

silicon nanoelectronics structure, where three separate layers of nanoscale 

lithography have been implemented with an overlay accuracy ≤ 20 nm. 

Courtesy of Neil Zimmerman, NIST.

New Capabilities:

•	 A CD measurement tool (mentioned above) that provides fast 

repeatable line width measurements of developed resist and 

final patterned structure for accurate calculation of process bias.

THE NANOFAB

1 6 | CNST

•	 A HMDS vacuum prime oven; vacuum deposition of HMDS 

resist adhesion promoter maximizes resist adhesion.

•	 A 5x reduction, i-line stepper will complete the NanoFab’s 

lithography tool set, providing a cost effective solution for 

creating geometries from the micrometer to nanometer 

scale. The stepper, along with our mask writer, will make 

an extremely powerful combination for rapid prototyping 

(2011).

•	 An automatic developer will provide the uniform and 

repeatable development necessary for robust lithography 

processes (2011).

Reactive Ion Etching (RIE)—The NanoFab has a strong RIE 

capability that includes two Unaxis parallel plate fluorine based 

systems; a Unaxis inductively coupled plasma (ICP) chlorine based 

system; a Unaxis ICP fluorine based deep silicon etcher; a XeF2

silicon etcher; and an oxygen barrel asher. Capabilities include 

basic dielectric etching, metal etching, III-V etching, and the Bosch 

deep silicon etch.
2010 | 1 7

‘‘

‘‘I would just like to say that my experience at the CNST was phenomenal. I 

was trained quickly, and it was clear that 

the priority on your end was to get me in 

the NanoFab and get my work completed 

as soon as possible. On that note, Marc 

and Lei were instrumental in helping me 

work out recipes quickly so that I could 

spend my time in production mode rather 

than trouble shooting. Their knowledge 

and experience were huge assets. 

Finally, everyone was extremely nice and 

pleasant to work with. I won’t hesitate 

to recommend the CNST to anyone in 

need of a top-notch fabrication facility.

Jered Haun

Massachusetts General Hospital

Harvard Medical School

The dry etch bay in the NanoFab cleanroom.
New Capabilities:

•	 Two Oxford ICP RIE systems were added to our etch suite. These 

two etchers provide cryogenic etching capabilities, improved 

chlorine based metal etching, and a III-V etching process that 

yields super smooth sidewall for photonic devices.

•	 A new broad beam ion mill etching tool will be invaluable for 

patterning materials that cannot be etched by RIE (2011).

Thin Film Deposition—The NanoFab can deposit many types of thin 

films, including metals, metal alloys, various dielectrics, silicon and 

parylene. The NanoFab staff can help you match the right film with 

the best deposition technique for your application. Our deposition 

methods include sputtering; electron beam evaporation; thermal 

evaporation; plasma enhanced chemical vapor deposition (PE-CVD); 

and low pressure CVD (LPCVD). Our thin film deposition tools include 

two Denton sputter systems; two Denton electron beam evaporators; a 

Unaxis PECVD system; three LPCVD tubes (silicon nitride, silicon dioxide 

and polysilicon); and a Parylene deposition system.

The NanoFab’s process control enables complex layered structures where 

excellent control over layer thickness, uniformity, and repeatability is 

essential, such as the structure in this SEM image, composed of 25 periods 

of alternating 27 nm-thick a-Si and 94 nm-thick Ag films. The NanoFab 

has deposited similar structures with thicknesses below 3 nm per layer. 

Courtesy of Henri Lezec and Kenneth Chau, NIST.

New Capabilities:

•	 An Oxford Atomic Layer Deposition (ALD) system uniformly 

deposits a monolayer at a time of a material across wafers of up 

to 200 mm in diameter. We currently have processes for hafnium 

oxide, platinum, silicon dioxide, and aluminum oxide. Several 

additional materials will be available (2011).

•	 In-situ phosphorus doping has been added to our polysilicon 

LPCVD system, enabling our complementary metal-oxidesemiconductor (CMOS) researchers to deposit highly doped 

polysilicon for gate material.

Diffusion/Oxidation—The NanoFab can support diffusions and 

oxidations at temperatures up to 1200 °C on wafer sizes up to 150 

mm in diameter. Processes include normal wet and dry oxidations, 

forming gas anneals and inert ambient diffusions. Some tubes are 

equipped with Trans-LC as a chlorine source for high purity oxides, 

THE NANOFAB

1 8 | CNST

[NanoFab	
  –	
  Thin	
  Film	
  Deposi9on)	
  

The	
  NanoFab's	
  process	
  control	
  enables	
  complex	
  layered	
  structures	
  where	
  excellent	
  cont

thickness	
  ,	
  uniformity,	
  and	
  repeatability	
  is	
  essen9al,	
  such	
  as	
  that	
  shown	
  here,	
  composed

of	
  alterna9ng	
  27	
  nm-­‐thick	
  -­‐Si	
  and	
  94	
  nm-­‐think	
  Ag	
  films.	
  	
  The	
  NanoFab	
  has	
  deposited	
  si

with	
  thicknesses	
  below	
  3	
  nm	
  per	
  layer.	
  	
  Courtesy	
  of	
  Henri	
  Lezec	
  and	
  Kenneth	
  Chau,	
  NIST.

such as gate oxides for CMOS applications. One furnace stack is 

reserved exclusively for CMOS applications. This stack is subject 

to regular oxide integrity monitoring by measuring the mobile ion 

concentration of the resulting oxides. A rapid thermal processor 

(RTP) is also available for very short, high temperature anneals. 

Ramp rates of 200 °C per second are easily achieved.

New Capabilities:

•	 One tube slot has been converted to support temperatures 

up to 1250 °C for extended periods of times, as is often 

required for silicon carbide processing.

•	 Ultra clean internal H2/O2 torches are available to improve 

uniformity, purity, and repeatability of wet oxidation 

processes.

Wet Processing—There are many nanofabrication processes 

that involve the use of chemicals to clean or etch various materials. 

The NanoFab stocks the most commonly used chemicals and the 
2010 | 1 9

Supporting all phases of nanotechnology development 

from discovery to production.

tools needed to use them safely, including several wet benches and fume 

hoods available for these purposes. Some fume hoods are dedicated 

for solvent use, whereas others are suitable for the many other aqueous 

acid and base solutions that are required for processing. The NanoFab 

also provides dedicated equipment for RCA cleans, KOH etching, and 

tetramethylammonium hydroxide (TMAH) etching. Ancillary equipment, 

such as spin-rinse-dryers and critical point dryers, is available as well.

New Capabilities:

• 	 An HF vapor etcher and a second critical point dryer specially 

designed for very small parts.

Inspection and Metrology—A necessary element of the NanoFab is 

the ability to inspect and measure Nanoscale structures. The NanoFab 

provides several different techniques for this purpose, including a field 

emission SEM (FESEM); a tabletop SEM; a spectroscopic ellipsometer; 

two reflectometers; a mechanical profilometer; a contact angle 

goniometer; two atomic force microscopes; a film stress measurement 

tool; and several optical microscopes. A dual beam FIB augments our 

inspection capabilities as well as being a process tool.

New Capabilities:

•	 An energy dispersive spectroscopy (EDS) system has been added 

to our FESEM to provide elemental analysis capability, including 

a compositional mapping tool.

•	 A state-of-the-art FEI Titan 80-300 TEM will provide 0.1 nm 

resolution at magnifications > 1,000,000x (2011).

•	 Two FEI Helios NanoLab 650 DualBeam FIBs offering extreme 

high resolution 2D and 3D characterization, 3D nanoprototyping, 

and high quality TEM sample preparation (2011).

Post Process—When processing wafers, often the researcher will 

need to thin the wafers, separate the individual dies, and then provide 

connections to outside circuitry or test fixtures. The NanoFab post 

process lab is equipped with some specialty tools for these purposes, 

including a dicing saw and wire bonder.

New Capabilities:

•	 A chemical mechanical polishing (CMP) tool for thinning wafers 

or for planarizing interlevel dielectric layers for multi-level 

metallization (2011).

The inspection bay in the NanoFab cleanroom.
CNST Research: Creating the 

Next Generation of Nanoscale 

Measurement Tools

While the NanoFab provides access to cutting-edge commercial tools 

and processes, CNST instrumentation scientists and engineers are 

creating the next generation. These talented staff members make their 

innovative instruments and methods available through collaboration 

with the world’s leading scientists to make and measure the nanoscale 

materials and devices of the future. As briefly discussed above, based on 

the collective input of our stakeholders regarding the key measurement 

barriers to advancing nanotechnology and the current capabilities and 

needs of NIST’s four Laboratories, we are currently emphasizing the 

following three research areas.

Future Electronics. In support of continued growth in the 

electronics industry beyond complementary metal-oxidesemiconductor (CMOS) technology, CNST researchers are 

developing new methods to create and characterize devices, 

architectures, and interconnects for graphene, nanophotonic, 

nanoplasmonic, spintronic, and other future electronics.

Nanomanufacturing. The Center is advancing the state of 

the art in nanomanufacturing by developing measurement tools 

and fabrication methods for both lithographic (“top-down”) and 

directed assembly (“bottom-up”) approaches.

Nano-enabled Energy Storage, Transport, and Conversion.

The CNST is creating new methods for elucidating light-matter 

interaction, charge and energy transfer processes, catalytic 

activity, and interfacial structure in energy-related devices.

Although the measurement research staff is organized into three 

Groups, each staff member applies his or her multidisciplinary expertise 

across multiple areas. An overview of the ongoing research in each 

Group follows, including key accomplishments from the past two years 

and emerging areas for new programs.

ELECTRON PHYSICS GROUP

The Electron Physics Group (EPG) conducts a wide range of crossdisciplinary instrumentation research focused on the development of 

innovative measurement techniques for nanotechnology. Building on 

a rich history of influential research in electron-surface interactions,

scanned-probe microscopy, electron-atom scattering, electron optics, 

and electron spectroscopy established while within NIST’s former 

Physics Laboratory, the EPG has expanded over the years into new 

technology areas as new measurement needs have arisen. Current 

research constitutes a significant portion of the CNST’s major thrust in 

future electronics, with strong efforts in nanomagnetics measurements 

for beyond-CMOS state-variable and information storage development; 

CNST RESEARCH

2 0 | CNST

state-of-the-art scanned-probe spectroscopy instrumentation for 

measurements of novel materials for next-generation devices; 

and theoretical studies of phenomena such as spin transfer 

torques and electron transport which guide development of new 

measurements enabling future device paradigms. 

Nanomagnetics—EPG research in nanomagnetics is currently 

aimed at addressing two of the most important measurement 

issues in the development of magnetic nanotechnology: imaging 

the magnetic structure within nanostructures, and measuring 

magnetization dynamics at the nanoscale. The properties of 

nanoscale magnetic structures can differ from those of macroscopic 

magnets for several reasons. Surfaces, edges, and interfaces 

become dominant, lithographic dimensions approach fundamental 

magnetic exchange lengths, and nanoscale fluctuations in material 

properties such as grain structure are also more important. 
2010 | 2 1

Ultimately, these nanoscale magnetic properties are not only a source 

of potential problems, but are also the basis for the development of new, 

higher density magnetic data storage technologies, and new magnetoelectronic and spintronic devices. We seek to develop measurement 

methods that can be used to provide an understanding of these 

nanomagnetic properties at a fundamental level by measuring how the 

electron spins, which are responsible for the magnetic properties, are 

arranged in a nanostructure, and how these electron spins respond to 

stimuli such as fields, currents, and mechanical stresses.

Electron Physics Group

December 2010

Jabez J. McClelland | Group Leader 

Teresa Figgs | Administrative Assistant

Project Leaders

Robert McMichael

Mark Stiles | NIST Fellow

Joseph Stroscio | NIST Fellow

John Unguris

Visiting Fellows

Young Kuk | Seoul National University

David Penn | NIST Emeritus

Daniel Pierce | NIST Fellow Emeritus

Postdoctoral Researchers

Shaffique Adam

Samuel Bowden

Jungseok Chae

Han-Jong Chia

Nikolai Klimov

Brenton Knuffman

Niv Binyamin Levy

Benjamin McMorran

Adam Steele

Tong Zhang

Graduate Researchers and Interns

Parakh Jain | Poolesville High School

Kevin Kubista | Georgia Institute of Technology

David Lee Miller | Georgia Institute of Technology

Engineering and IT Support Staff

Alan Band

Steve Blankenship

Barbara Coalmon

Frank Hess

Glenn Holland

Matthew Manganello

David Rutter
Our primary magnetic imaging technology is the NIST-developed 

Scanning Electron Microscopy with Polarization Analysis (SEMPA) 

method, which provides a direct, high resolution view of the 

magnetization in magnetic nanostructures with 10 nm spatial resolution, 

1 nm depth resolution, and equal sensitivity to all three components 

of the magnetization vector. In recent work we have demonstrated 

a new approach to depth-profiling the magnetic structure in several 

materials relevant to perpendicular magnetic storage media and 

spintronic applications, making use of a combination of SEMPA imaging 

and low-energy ion milling. For example, SEMPA measurements on 

patterned Co/Pd multilayer recording media with graded magnetic 

anisotropy, prepared by our collaborators at the University of California, 

Davis, revealed how the domain structure evolved at different depths 

in the graded films (see the Project Highlight, Imaging 3D Magnetic 

Nanostructure in Ferromagnetic Multilayers). SEMPA was also used 

to study a synthetic antiferromagnet consisting of an antiparallel 

coupled Co/Ru/Co multilayer, used by Michigan State University to test 

ferromagnet/superconductor proximity effects.

SEMPA is also being used to image the magnetic state of nanoscale 

patterned ferromagnetic thin films that are the building blocks of 

magnetic logic circuits. Such circuits are potential candidates for 

use in low power applications in future electronics. So far we have 

successfully measured static magnetization arrangements in structures 

provided by the University of Notre Dame and the University of South 

Florida. We are currently extending the SEMPA measurements to image 

the magnetic state of active devices—devices in which the magnetic 

state can be switched using magnetic fields or current-induced spin 

torques.

SEMPA images from a patterned array of 100 nm-wide elements used for

magnetic logic.

As part of our magnetic imaging program we are also pursuing new 

approaches that will allow us to improve spatial resolution to well 

below 10 nm. To this end, we have investigated the production and 

application of electron vortex beams in a TEM. These electron beams 

have angular momentum that can interact with a ferromagnetic sample 

in a manner similar to the magnetic circular dichroism contrast obtained 

CNST RESEARCH

2 2 | CNST

using synchrotron radiation, but potentially with the higher spatial 

resolution of the TEM. Electron diffraction gratings with well 

defined dislocations were produced in the NanoFab and used to 

successfully generate electron beams with quantized angular 

momentum of up to 100 h per electron. These electron vortex 

beams are analogous to optical vortex beams and are expected 

to be similarly useful in various electron microscopy applications 

from magnetic imaging to imaging weak-phase biological objects.

Our research program to develop magnetization dynamics 

measurements has demonstrated the ability to provide essential 

information about spin dependent transport, magnetic resonances, 

and magnetic switching at the nanoscale. Measurements of these 

properties create a foundation for the design and development of 

a wide variety of magnetic nanodevices and electron spin-based 

electronics.
2010 | 2 3

We have developed a method to measure the polarization of electrical 

current carried in magnetic metals via the “spin wave Doppler effect.” 

In the simplest terms, the electrons that carry charge in an electrical 

current also transport magnetic moment via the electron spin. The 

resulting drift velocity of the magnetization adds vectorially to the 

velocity of propagating spin waves in a way that is very nearly identical 

to the classical Doppler shift of wave propagation in a moving medium. 

By measuring how the propagation of spin waves depends on the sign 

and magnitude of current, it is possible to determine the polarization 

of the current; i.e., the relative magnitude of currents carried by up 

and down spins in the magnetic metal. A more detailed description of 

this experiment is provided in the Project Highlight, Measurement of 

Current Polarization by Doppler-Shifted Spin Waves.

We have also extended a ferromagnetic resonance spectroscopy 

technique to enable measurement of the magnetic properties of edges 

in lithographically fabricated nanostructures. Edges become more 

important for smaller structures simply because more of the structure is 

close to an edge. Most recently, we have shown that this technique can 

be used to observe the effects of oxidation on film edge properties, in 

structures lightly oxidized in oxygen plasma and in structures annealed 

in oxygen. These measurements showed that both oxidation methods 

made the edges less ideal, but that the annealing also caused changes 

in the film away from the edges. In another set of experiments and 

models, we demonstrated that the effects of interactions between 

magnetic layers at the edges of patterned multilayers could be 

measured.

In a new program aimed at expanding measurements of nanomagnetics 

dynamics to include high spatial resolution, we have developed a 

ferromagnetic resonance force microscope system. Working on some 

of the same principles as electron paramagnetic resonance (EPR) force 

microscopes that have detected single electron spins, and nuclear 

magnetic resonance (NMR) force microscopes that have performed 

magnetic resonance imaging on viruses, this instrument is designed 

to allow spectroscopy of the magnetization dynamics in individual 

nanostructures with the goal of facilitating nondestructive evaluation 

of the magnetic properties of buried magnetic devices. Using this 

instrument we have recently localized spin wave modes using the 

dipole field of the cantilever tip. Emerging applications will include 

such future electronics measurements as performing failure analysis of 

defective devices in arrays.

Accomplishments: 

•	 Demonstrated the ability to measure the three-dimensional 

magnetization in multilayer magnetic storage media with graded 

anisotropy.

•	 Demonstrated the imaging of magnetic logic circuits (in 

collaboration with the University of Notre Dame and the 

University of Southern Florida).

•	 Developed methods to image the magnetic structure of 

lanthanum-strontium-manganese-oxide (LSMO) and other 

difficult to prepare materials.
•	 Produced electron vortex beams with up to 100 h per electron of 

quantized orbital angular momentum in the TEM.

•	 Showed that current polarization can be measured by observing 

the spin wave Doppler effect in magnetic metals (in collaboration 

with Hitachi Global Storage Technologies and North Carolina 

State University).

•	 Demonstrated that edge mode ferromagnetic resonance 

spectroscopy can be used to measure effects of oxidation and 

interlayer coupling.

•	 Designed and installed a ferromagnetic resonance force 

microscope.

Emerging Research:

•	 Develop measurements that probe the mechanisms of electrical 

control of magnetization in nanoscale devices.

•	 Create new ways to observe how domain-wall chirality behaves 

in its role as a logic state in nanomagnetic logic circuits.

•	 Develop a magnetization imaging electron microscope based on 

using electron vortex beams with orbital angular momentum.

•	 Demonstrate the detection of ferromagnetic resonance in 

nanostructures using sensitive cantilever techniques.

Atomic-Scale Characterization and Fabrication—This research 

is focused on developing new measurement and fabrication methods 

with atomic-scale precision. The experimental program emphasizes 

the design of custom instrumentation intended to push the frontiers 

of nanoscale characterization. Using state of the art scanning 

probe techniques, we have developed a new range of measurement 

capabilities that can provide essential input for a diverse set of new 

technologies in future electronics.

Recent work has focused on measurements on graphene, a single 

sheet of carbon with a promising potential for future electronic 

material applications because of its low scattering rates and high 

carrier mobilities. Magneto-electronic measurements are made using 

scanning tunneling microscopy (STM) and spectroscopy measurements 

in high magnetic fields. Two different types of graphene are used for 

these studies: epitaxial graphene samples grown on SiC obtained from 

the Georgia Institute of Technology in collaboration with the research 

groups of Professors Phillip First and Walter de Heer; and exfoliated 

graphene devices on SiO2

 substrates fabricated in the CNST NanoFab. 

With the epitaxial graphene samples, we made direct measurements 

of the Landau quantization resolving all four quantum states arising 

from electron and valley symmetries. These measurements were made 

using a new high resolution ultra-low temperature scanning tunneling 

microscope operating at 10 mK. The exfoliated graphene devices 

allowed us to investigate the effect of substrate interactions on the 

graphene electrical properties. New scanning spectroscopic techniques 

were developed to map out the electronic structure as a function of 

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2 4 | CNST

carrier density using STM “gate” mapping measurements. This 

work was performed in collaboration with Nikolai Zhitenev in the 

CNST Energy Research Group, as well as with David Newell and 

Angela Hight-Walker in NIST’s Physical Measurement Laboratory.

Accomplishments: 

•	 Developed measurements to determine the atomic structure 

of the edges of graphene islands grown on SiC.

•	 Measured magneto-tunneling conductance oscillations on 

graphene and used them to determine the dispersion of 

graphene’s band structure.

•	 Created a method of analyzing STM moiré patterns to 

determine very small strains in multilayer graphene.
2010 | 2 5

Scanning tunneling spectroscopy map of graphene, showing Landau level 

dependence on magnetic field up to 14 T.

•	 Demonstrated measurements of the magnetic quantum energy 

level structure (Landau levels) in graphene, revealing how the 

level structure scales with Landau index and magnetic field.

•	 Measured the spatial properties of the quantum Hall states in 

graphene, and showed how these properties can be related to 

geometric structural properties.

•	 Developed a best-in-the-world, ultra-low temperature, scanning 

probe microscopy system that operates at temperatures as low 

as 10 mK and in magnetic fields as high as 15 T for high energy 

and spatial resolution measurements of electronic structure in 

nanoelectronics materials and devices.

•	 Using the new milliKelvin STM, characterized the four-fold 

internal structure of a graphene Landau level, and determined 

the relative energy splitting relating to spin and valley degrees 

of freedom.

Emerging Research:

•	 Develop microscopic measurement methods for future electronic 

materials, such as graphene and topological insulators, in 

real device geometries to understand the role of substrates, 

insulators, and contacts in device performance.

•	 Create methods to grow and characterize topological insulators, 

a new class of materials with promising electronic properties.

•	 Advance spin-polarized scanning tunneling spectroscopy 

measurements for future electronic materials, such as graphene 

and topological insulators.
Modeling Nanostructures in Mesoscopic Environments—The 

EPG is using theory, modeling, and simulation to provide key insight in 

interpreting measurements of the structural, dynamic, electronic and 

magnetic properties of nanostructures and associated systems. The 

goal is to enable and stimulate the development of new measurement 

capabilities by elucidating the underlying physical processes in these 

systems. One aspect is to reveal the new physics that becomes 

important as electronic and magnetic devices approach nanometer 

length scales. Using various theoretical methods, this research 

interprets experiments, suggests new directions, and identifies possible 

improvements in measurements, devices, processes or systems. 

One focus has been spin-transfer torques—the “forces” on magnetic 

systems that arise when electrical current passes through a nonuniform magnetization either in a multilayer or across a domain wall. 

The torques, which are strong enough to induce magnetic dynamics, 

are being intensely studied for device applications, with experiments 

underway at the CNST and around the world. Possible applications 

include Magnetic Random Access Memory (MRAM), in which memory 

elements consist of two ferromagnetic elements separated by a thin 

MgO tunnel barrier, as well as domain wall devices, in which the 

information is stored in the positions of domain walls that are moved 

past a sensing element. Motivated by new measurements, EPG 

theorists have computed the properties of spin-transfer torques in 

such systems with a range of approaches in order to understand how 

a variety of extrinsic effects modify the torques. Another important 

process underlying the performance is the magnetic damping; EPG 

theorists have addressed this by calculating the variation of magnetic 

damping that can occur in such nanoscale devices.

Calculations of the effect of spin-orbit coupling on the band structure of 

ferromagnetic GaMnAs.

An additional focus of our theory effort in the EPG is motivated by CNST’s 

experimental studies of graphene. This research includes developing 

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2 6 | CNST

models to complement the new scanning probe measurement 

capabilities that have been demonstrated in graphene. A variety 

of approaches have been used to help interpret the data, including

developing models for transport to understand the viability of 

graphene for use in electronic devices.

Accomplishments: 

•	 Carried out detailed calculations of spin transfer torques in 

the presence of real world complications, including spinorbit coupling, finite temperature, finite bias, and disorder.

•	 Calculated the transport properties of graphene bilayers.

•	 Calculated the damping parameters for transition metal 

ferromagnets, including their anisotropy and wave vector 

dependence, in addition to their variation in the presence 

of current.
2010 | 2 7

Emerging Research:

•	 Determine the effect of interfacial spin-orbit coupling on domain 

wall motion.

•	 Understand charge transfer in few-layer graphene systems.

Nanoscale Measurement and Fabrication Using 

Laser-Controlled Atoms—The central theme of this research lies 

in taking advantage of the high degree of control afforded by laser 

manipulation of neutral atoms to develop new measurement and 

fabrication technologies for nanotechnology. Neutral atoms can 

be focused, deflected, trapped, state-selected, and cooled with an 

extraordinary level of control and precision using the mechanical effects 

of near-resonant laser light. The coldest temperatures on earth, the 

most precise clocks, and entire new forms of matter are achieved in 

this way. Such exquisite control opens many opportunities for new 

nanotechnology measurement applications. Putting these processes 

to use has enabled us to address such diverse needs as production of 

high resolution focused ion beams for nanofabrication and imaging, 

deterministic production of single atoms “on demand,” and resist-free 

in situ fabrication of nanoscale features.

Current activities in this research area are concentrated on developing 

and applying our recently demonstrated magneto-optical trap ion 

source, or MOTIS (U.S. Patent no. 7,709,807). This source takes 

advantage of the 100 μK temperatures available in a magnetooptical trap to create an ion beam with very low emittance and high 

brightness. By ionizing neutral atoms in the trap and extracting them, 

a beam is created without the need for an extremely small source size 

such as is found in conventional liquid-metal ion sources. The result 

is an ion source with focal properties rivaling or surpassing existing 

sources, with the following added benefits: a wide variety of possible 

ionic species; a very narrow energy spread; and the potential ability 

to implant single ions “on demand” with nanometer precision using 

techniques developed in previous years in the EPG. This new ion 

source will enable a diverse new set of focused ion beam applications, 

including contamination-free milling, new beam chemistry mechanisms 

allowing deposition and removal of material for applications such as 

integrated circuit repair, damage-free ion microscopy with new contrast 

mechanisms, and controlled doping of semiconductors.

Our work on MOTIS development has been greatly enhanced by a 

cooperative research and development agreement with FEI Co., an 

Oregon-based major supplier of focused ion beam systems. Through 

this mutually-beneficial and active collaboration, NIST has gained 

access to equipment in the form of a focused ion beam system in place 

at the CNST, which we are free to modify and adapt for use with a 

MOTIS, as well as the expertise of the Beam Development Group at FEI. 

Researchers at FEI gain early access to our groundbreaking technology.

Having just demonstrated some of the unique capabilities of the MOTIS 

this year, we are now beginning a series of exploratory research thrusts 

on a broad range of possible applications—ranging from novel beam 

chemistries to single ion implantation for color center formation—that 

will include development of ion sources with other species, experiments 

with very low and very high energy ions, and pushing the resolution of 

the focused beam system to its limit.
Accomplishments: 

•	 Constructed a lithium ion source based on the MOTIS principle.

•	 Carried out a series of calculations and measurements of the 

effects of Coulomb interactions on Li MOTIS performance.

•	 Successfully mounted the Li MOTIS on an FEI-provided focused 

ion beam system, achieving a major milestone in this cooperative 

research project.

•	 Demonstrated the first-ever Li ion images, with < 30 nm resolution 

using 2 kV Li ions.

•	 Constructed an ion focusing and deflection system for existing 

Cr MOTIS.

•	 Demonstrated first-ever focused Cr ion images.

•	 Conducted exploratory measurements on Cr color centers in 

diamond.

Emerging Research:

•	 Exploratory measurements on Cr color centers in diamond.

•	 Converting Cr and Li ion beam systems to allow operation up to 

30 kV.

•	 Exploring a wide array of imaging and nanofabrication 

applications using Li and Cr focused ion beams. 

•	 Constructing MOTIS realizations with other ionic species such 

as Cs and Er, with applications such as secondary ion mass 

spectrometry (SIMS) in mind.

Energy Research Group

The Energy Research Group (ERG), the newest group in the CNST, 

develops instruments designed to reveal the nanoscale physical and 

chemical processes and properties critical to advances in energy 

conversion, transport, and storage. Research in this group has only 

recently begun, with most of the technical staff members joining the 

Center within the past 18 months. The Group’s research includes 

nanoscale characterization of light-matter interaction, charge and 

energy transfer processes, catalytic activity, and interfacial structure 

in energy-related materials and devices. The current focus is on 

the creation of instrumentation for nanoscale characterization of 

photovoltaic and thermoelectric materials and devices, nanoscale 

measurements of electrochemical processes for energy storage and 

conversion, and computational models of energy and charge transfer 

dynamics.

Nanoscale Optoelectrical Characterization of Photovoltaic 

Materials and Devices—Large-scale implementation of solar 

power generation will require photovoltaic (PV) devices with a ratio 

of efficiency to cost that is much higher than existing silicon-based 

systems. Such “next generation” devices will depend on new materials 

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2 8 | CNST

and innovative device structures. Thin-film PV devices, also 

called second generation devices, are becoming competitive with 

Si-based technologies, but face technical challenges to achieve 

their potential for high efficiency. Third generation devices are 

now under development that exploit nanoscale three-dimensional 

(3D) structures to achieve higher efficiencies at affordable 

manufacturing cost, but are still less efficient than current 

commercial solar panels. All these devices feature sophisticated 

nanometer and micrometer scale structures that have significant 

effects on overall device performance. The ERG is developing 

the measurement tools and techniques along with the requisite 

modeling approaches needed to characterize the physical 

processes related to light absorption, energy transfer, and carrier 

dynamics in both second and third generation PV materials and 

devices.
2010 | 2 9

Energy Research Group

December 2010

Nikolai Zhitenev | Group Leader 

Amanda Dyson | Administrative Assistant

Project Leaders

Andrea Centrone

Paul Haney

Fred Sharifi

Veronika Szalai

A. Alec Talin

Postdoctoral Researchers

Myung-Gyu Kang

Raymond Kallaher

Dmitry Ruzmetov

Ceren Susut

Third-generation cells based on 3D novel nanostructures such as dyesensitized solar cells, organic bulk heterojunctions, nanocomposite 

materials, quantum dots, and nanocrystals embedded in polymer 

matrices typically show low performance caused by a wide range of 

poorly understood mechanisms, including nanomorphology, inefficient 

electron transfer at interfaces, charge carrier mobility, and impurities. 

The ERG is developing multiple probe-based optical and electrical 

characterizations combined with structural measurements, crosssectioning of active devices, and nanodevice fabrication, with the goal 

of obtaining complete information on the relevant physical phenomena 

at the nanoscale in PV devices. Scanning probe techniques such as 

conductive atomic force microscopy (AFM) and STM will be correlated 

with local photoluminescence (PL), surface potential, photocurrent 

measurements, and local spectral response measurements on thirdgeneration and thin-film PV materials and devices. The measurement 

development includes the design of advanced local probes such as 

integrated electrical amplifiers and plasmonic lenses on fibers. (See the 

Project Highlight, Nanoscale Characterization of Organic Photovoltaic 

Devices.)

Fabrication of plasmonic lens on a fiber. Top: A gold layer is evaporated onto 

a cleaved fiber, and circular slits concentric with the fiber core are cut through 

via FIB. Bottom: SEM image of a lens cross-section.
Another approach to gaining spatial information about the physical 

processes and characteristic length scales in PV materials is through 

fabrication and characterization of PV test materials and devices with 

spatially and morphologically defined 3D structure. The characteristic 

length scales for energy processes in modern PV materials range from 

a few tens of nanometers for exciton diffusion, to a few hundreds of 

nanometers or a few micrometers for grain sizes in thin film materials 

or carrier diffusion length, respectively. These length scales are well 

within the capabilities of modern lithographic techniques such as 

electron beam, imprint, or photolithography. The ERG is collaborating 

with researchers in the NIST Material Measurement Laboratory (MML) 

to fabricate and measure regular, 3D-structured PV materials, such as 

electrochemically-deposited compound semiconductors and chemical 

vapor deposited nanowires. Another ERG project, in collaboration 

with the University of Michigan, University of California, Berkeley, 

and Sandia National Laboratory, has demonstrated and characterized 

radial p-n junction photovoltaic devices with controlled 3D-structure 

fabricated with simulated metallurgical grade Si (less pure, lower 

cost). This project developed a quantitative, physics-based model 

explaining the experimental observations, and thereby led to specific 

recommendations for optimal device geometry (see the Project 

Highlight, Efficiency Enhancement of Copper Contaminated Radial p-n

Junction Solar Cells).

Accomplishments: 

•	 Developed measurements of local photoresponse in polymer 

solar cells with spatial resolution in the range from 50 nm via 

conductive AFM, to 200 nm to 1000 nm via nanofabricated 

contacts.

•	 Measured the 3D nanomorphology in polymer solar cell through 

application of AFM and sectioning techniques.

•	 Developed models to access the impact of inhomogeneous 

nanoscale morphology on efficiency of organic PV device.

•	 Created quantitative models for 3D-structured PV materials 

based on Si radial p-n junctions.

•	 Designed and fabricated plasmonic lenses integrated with 

optical fibers.

Nanomaterials in Electrochemical Energy Conversion and 

Storage—A number of new approaches to creating more efficient 

devices for energy harvesting, storage, and conversion are based on the 

exploitation of nanostructured materials in electrochemical systems. 

Incorporating nanostructured electrodes into electrochemical energy 

conversion and storage devices offers several advantages for a variety 

of transportation and other “green” energy infrastructure applications, 

including batteries, fuel cells, and so-called “supercapacitors.” In each 

of these devices, nanostructured materials can be used to increase the 

surface area where the critical chemical reactions occur within the same 

volume and mass, thereby increasing the energy density, power density, 

CNST RESEARCH

3 0 | CNST

electrical efficiency, and physical robustness of the system. Such 

materials also have the potential to lower manufacturing costs.

The fabrication and effective use of nanomaterials in 

electrochemical devices presents formidable challenges, however. 

In particular, scientists do not yet fully understand the interfacial 

reactions and phase transformations that accompany charge 

transfer at electrode/electrolyte interfaces. Controlling these 

phenomena requires careful measurements and a fundamental 

knowledge of how nanoscale surface composition, structure, and 

defects affect these processes.

To address these challenges, the ERG is building several 

experimental platforms designed for characterizing the 

physico-chemical processes that accompany charge transfer 

in electrochemical systems. One system is designed to rapidly 

transfer within an inert atmosphere a specimen from a liquid 
2010 | 3 1

electrochemical cell to a multi-analysis ultra high vacuum chamber, 

where surface structure and composition can then be determined using 

electron, scanning probe, and X-ray beam methods. This system will 

be used to characterize a range of electrochemical energy conversion 

and storage devices, including batteries, fuel cell electrocatalysts, 

electrochemical capacitors, and photoelectrochemical cells for 

hydrolysis. These measurements will provide the key knowledge 

needed to improve the efficiency and performance of such devices.

Another system, already operational, uses surface plasmon-polariton 

waves (SPPs) for real-time, dynamic characterization of processes at 

electrode/electrolyte interfaces. Because SPPs are confined to the metal/

dielectric interface, they are highly sensitive to changes in the electrode 

surface charge density and the electrolyte dielectric. In addition to SPP 

spectroscopy, The ERG is also integrating a Raman spectrometer with 

an atomic force/scanning electrochemical microscope. This system will 

be dedicated to correlating local photoelectrochemical activity in water 

splitting catalysts with nanometer scale morphology and chemical 

composition.

Finally, the ERG is fabricating complete, all-nanowire Li-ion batteries 

and using these to characterize the physical and chemical processes 

that accompany the flow of charge directly in the scanning electron 

microscope. The experimental observations will be used to develop 

physics-based models to describe the electrochemical behavior of these 

devices.

Measurement of nanowire-based battery using nanomanipulator in SEM 

(false-color image).

To obtain the detailed mechanisms of electrocatalytic reactions 

relevant to energy conversion, the ERG is developing spectroelectrochemistry of nanocatalysts by exploiting plasmonic properties 

and plasmonic antennas. Catalytic nanostructures with well defined 

geometry, dimensions, composition, and plasmonic resonance will be 

used as a platform for simultaneous electrochemical and spectroscopic 

interrogation. The role of plasmon excitations on the rates of charge 

transfer will be specifically addressed using both experimental and firstprinciple theoretical methods.
Emerging Research:

•	 Characterizing nanowire-based solid-state batteries.

•	 Measuring charge accumulation and reactions at electrochemical 

interfaces using nanoplasmonics.

•	 Using Raman spectroscopy for spatially-resolved strain mapping 

in nanostructured Li-ion battery electrodes.

•	 Correlating local activity, morphology, and composition in solar 

hydrogen electrodes.

Nanostructured Thermoelectrics—Finding alternative energy 

sources is one approach to satisfying the ever growing demand for 

energy; another is converting energy that is not used and generated 

in the form of waste heat. On the large scale, thermoelectric 

conversion of waste heat is the focus of serious and significant study 

in industries creating turbine machinery for the electricity generation. 

These turbines can individually generate power at levels in excess 

of 500 MW, and newly-constructed power plants often have power 

production approaching several gigawatts. These turbines are highly 

efficient, often operating at 60 % efficiency, and approach the Carnot 

value. A major limiting factor in efficiency occurs at the final stage 

compressor, where the gas temperature is in the range of 200 °C to 

300 °C. At this temperature the low temperature/pressure of the gas 

does not allow for efficient extraction of mechanical energy and thus 

it is exhausted as waste heat. Here, thermoelectrics can allow for 

direct conversion of waste heat into electricity. In a centralized source 

as power plant, improvements of a few percent in energy production 

will be significant. In the absence of regulatory edicts, cost-effective 

implementation of thermoelectrics requires a three-fold improvement 

over existing thermoelectric material efficiency. There are also several 

smaller-scale applications of this technology, including in trucks and 

automobiles. Internal combustion engine platforms convert only about 

25 % of the chemical energy from gasoline into kinetic energy; the other 

75 % is lost in the form of mechanical friction and exhaust gases. For 

the latter, thermoelectric generators are being considered for use in 

converting exhaust heat into electricity, allowing for removal of several 

components, including on-board generators, and increasing overall 

efficiency in the range of 5 % to 10 %.

Recent advances in nanostructured thermoelectric materials have 

increased the conversion efficiency of the thermoelectric devices to 

the point that they may soon allow cost-effective operation. Several 

scientific developments have resulted in improvements in the 

thermoelectric figure of merit, ZT, which is a measure of conversion 

efficiency. These developments may be broadly categorized into two 

distinct mechanisms: altered electronic density of states, and altered 

charge transport. They involve fabrication of reduced-dimensional 

structures or lamellar-type structures

Characterizing a thermoelectric material requires precise measurements 

of electrical conductivity, thermal conductivity, and thermopower 

(the voltage produced per degree temperature difference across the 

CNST RESEARCH

3 2 | CNST

material). To address this need, the ERG is developing new 

measurement tools and techniques that can be applied to both 

conventional and unconventional thermoelectric materials, 

allowing for a more accurate determination of the key properties, 

including ZT.

The ERG has designed an innovative heat pipe, incorporating 

high-precision thermometers that can locally probe temperatures 

ranging from room temperature to 800 K with an accuracy of a few 

milliKelvin. The design is versatile, allowing for measurements 

on samples of different structure and composition, ranging from 

nanowires grown in templates with diameters of approximately 

tens of nanometers, to macroscopic materials containing lamellar 

nanostructures. By providing a complete set of measurements, 

this approach will enable the comprehensive characterization 

of nanostructured materials needed to advance commerciallypromising thermoelectric technologies.
2010 | 3 3

Ultrahigh vacuum instrumentation for measuring the performance of 

nanostructured field emitters.

Emerging Research:

•	 Developing methods to characterize thermopower.

•	 Measuring thermal conductivity in nanostructured thermoelectric 

materials.

•	 Characterizing chalcogenide lamellar structures.

•	 Measuring the thermal properties of narrow-band semiconductor 

nanowires.

Characterizing Field Emitters Based on 1D Structures—Cold 

cathode emitters could potentially have one of the largest impacts of 

any nanotechnology, as there are realistic applications across several 

significant industries. Possible applications range from energy-saving 

displays, to medical and security imaging, to microwave electronics, 

to compact free-electron lasers. The goal of this project is to develop 

methods for measuring the local current density and emittance 

(transverse kinetic energy or beam spread) of nanostructured emitters.

Accurate measurements on two parameters (local current density and 

emittance) are required to understand and validate physics models of 

cold cathode emitters. At present, experimental characterization is 

limited to measurements of current over large areas, yielding average 

current density. As current densities of cold cathode emitters are highly 

non-uniform over the emission area, present techniques do not provide 

sufficient information so as to enable better understanding of the 

underlying emission physics of these systems.

Emerging Research:

•	 Measuring local current density and emittance.

•	 Fabricating model emitter arrays comprised of carbon nanotubes 

and InP nanowires.
Nanofabrication Research Group

The Nanofabrication Research Group (NRG) conducts research to 

support the CNST’s nanomanufacturing research thrust through the 

creation of new measurement methods to enable the development and 

effective use of nanomanufacturing and nanofabrication processes. 

These methods include both lithographic (“top-down”) and directed 

assembly (“bottom-up”) approaches. Much of the NRG’s research 

is directed towards both measurements capable of elucidating the 

fundamentals of nanofabrication processes as well those suitable for 

use in a high-throughput nanomanufacturing environment. The staff 

members’ expertise spans a very wide range, but the following main 

themes underlie much of the work: nanoscale optical measurements; 

dynamic in situ measurements; nanomechanics; and the stochastic 

behavior of nanoscale systems. Project leaders in the NRG also make 

significant contributions to research across the CNST, supporting the 

energy and future electronics focus areas. Output from the NRG is 

rapidly growing as the Project Leaders’ laboratories come on line.

Nano-Optics—Light in or near the visible range offers tremendous 

opportunities for sensitive measurements of the properties of 

nanostructures. Typically, however, the diffraction-limited optical spot 

size of about a wavelength makes measurements of single nanoscale 

objects problematic. Nanophotonics and nanoplasmonics both provide 

the means by which light can be confined to the nanoscale, enabling 

such measurements.

Sub-wavelength features etched into high-index semiconductor and 

dielectric materials such as silicon, silicon nitride, and gallium arsenide 

can be used to produce waveguides and resonant cavities that allow for 

the precise manipulation of the flow of light at very small dimensions. 

With advanced fabrication techniques, the losses can be minimized, 

enabling the production of devices with extremely high quality factors. 

The NRG’s research is focused on the fabrication and characterization of 

such structures and their use in measuring phenomena related to cavity 

quantum electrodynamics involving individual quantum dots, singlephoton emitters, and signal transduction.

Current activities in this area make use of a novel cryogenic fibertaper probe system. This system uses the evanescent field extending 

from an optical fiber (adiabatically tapered to a diameter on the 

order of a micrometer) to interact with microcavity devices and 

nanostructures. Light injection and extraction is very efficient with this 

device, enabling precise spectroscopic measurements to be made on 

semiconductor waveguides and resonators containing single quantum 

dots. Measurements exploring novel strong light-matter interaction 

effects in these systems have been performed in collaboration with 

the University of Rochester. Individual solution-synthesized quantum 

dots can also act as single photon sources and have the potential to 

CNST RESEARCH

3 4 | CNST

be integrated with conventional silicon semiconductor devices, 

bringing quantum information transmission a step closer to 

practice. In collaboration with Columbia University, a low density 

of quantum dots was deposited on a Si photonic crystal and the 

fiber-taper waveguide was used to probe their spectroscopic 

behavior close to the 1.55 μm telecommunication wavelength. 

(See the Project Highlight, Measuring Light-Matter Interactions in 

Chip-Based Optical Cavities.)
2010 | 3 5

Nanofabrication Research Group

December 2010

J. Alexander Liddle | Group Leader 

Yeehing Lam | Administrative Assistant

Project Leaders

Vladimir Aksyuk

Andrew Berglund

Rachel Cannara

Gregg Gallatin

Henri Lezec

Renu Sharma

Kartik Srinivasan

Visiting Fellows

C. Stephen Hellberg | Naval Research Laboratory

Benjamin Shapiro | University of Maryland

Mihaela Tanase | University of Maryland

John Weiner | Université Paul Sabatier

Postdoctoral Researchers

Maxim Abashin

Amit Agrawal

Adam Berro

Marcelo Davanco

Zhao Deng

Kan Du

Suyong Jung

Seung-Hyeon (Sarah) Ko

Stephan Koev

Pramod Mathai

Stefano Mazzucco

Houxun Miao

Sukumar Rajauria

Matthew Rakher

Graduate Researcher

Jaime Javier Juarez | Johns Hopkins University

In collaboration with NIST’s Information Technology Laboratory, we 

have developed a method for taking 1.3 μm wavelength photons, which 

have good long-distance transmission properties, and efficiently upconverting them to easy-to-detect photons at 710 nm. Significantly, the 

quantum, single-photon properties of the source are preserved in this 

process. This work clearly demonstrates that it is possible to integrate 

the disparate quantum systems needed for information transmission 

and computation.

Metal nanostructures can also be used to guide light at the nanoscale 

by means of surface plasmon-polaritons (SPPs)—waves confined to 

the interface between metals and dielectrics. Optical confinement 

takes place in all three dimensions, leading to extremely large field 

enhancements that can be used to create strong interactions with nonlinear materials. The enhanced effect of small external perturbations 
CNST RESEARCH

3 6 | CNST

on the behavior of the light, such as the absorption of a single 

molecular layer, can be used both in sensing and switching 

applications. NRG research is focused on the design and fabrication 

of novel components for measurement and communications based 

on nanoscale plasmonic effects, thereby essentially recreating the 

toolkit of macroscale optical devices in the deep sub-wavelength 

regime. SPPs also offer the ability to create novel devices unlike 

anything available at the macroscale. The unique dispersion 

characteristics of SPPs traveling in nanostructured metallodielectric materials enable metamaterials with properties such 

as negative refractive indexes to be created. These materials are 

the subject of intense study and may have significant potential for 

imaging and manipulating matter at the nanoscale.

The utility of plasmonic devices for sensing and measurement 

applications relies on a clear understanding of how light behaves 

in the near and far-fields, both theoretically and experimentally. 

Recent work has focused on advancing this understanding for 

simple geometries such as slits and holes that are often used in 

sensor applications. We have used a combination of modeling 

and far-field measurement to demonstrate how the illumination 

of a single slit can efficiently generate surface waves. The phase 

shift (close to –π) of the surface waves compared to the reference 

wave creates interference that, in the case of periodic slit arrays, 

controls the transmission profile. The surface waves can readily 

be perturbed by, for example, small changes in the surface 

chemistry—the reason they may be used in sensing. However, 

we can also use the change in chemistry induced by those waves 

to learn about the field distributions of the plasmonic devices 

themselves. We are working with collaborators at the University 

of Texas at Austin to develop a sublimation-switch resist material 

that is sensitive at long wavelengths (≈700 nm) to map surface 

fields. Initial results qualitatively agree with modeling results, 

but show many interesting features that may relate to small 

imperfections in the actual experimental devices. The technique 

is simple and can be used over large areas, and we are currently 

working to make it fully quantitative.

Accomplishments:

•	 Developed novel cryogenic optical fiber-taper probes for 

characterizing nanophotonic devices.

•	 Demonstrated single-photon up-conversion that enables 

efficient measurements of nanoscale, near-infrared quantum 

emitters.

•	 Performed detailed spectroscopy of single PbS quantum 

dots in collaboration.

•	 Developed a novel, broadband-sensitive resist that can 

be used to quantitatively determine time-averaged field 

intensities in nanoplasmonic devices.

•	 Created techniques to enable the measurement of the 

optical and optomechanical response of 3D plasmonic 

metamaterials with a negative index of refraction.

SEM image of an on-chip cavity optomechanical transducer for atomic 

force microscopy applications. A high quality factor silicon microdisk 

optical resonator is used to measure the megahertz frequency vibrations 

of an adjacent nano-cantilever, providing high displacement sensitivity, 

bandwidth, and dynamic range.
2010 | 3 7

Nanomechanics—Nanomechanical systems can be used for both 

sensing and actuation. Their small size can render them extremely 

sensitive to the smallest perturbations, or capable of the most delicate 

manipulation. They are thus both objects of study and used for the 

investigation of other nanoscale devices.

Friction accounts for much of the energy wasted in industry, and it has 

a strong impact on the reliability of devices. This impact is true down 

to the nanoscale, where surface interactions dominate bulk forces, 

and the effects of friction, adhesion, and wear hinder the development 

of complex nanomechanical devices. The NRG’s research is directed 

to developing new ways to measure the fundamental mechanisms 

governing friction. One area of interest is the loss of waste heat to 

phonons generated at sliding interfaces. A greater understanding of 

friction can help improve the energy dissipation and wear characteristics 

of mechanical systems (including those at the macroscale), as well as 

help guide the engineering of electromechanical devices that require a 

balance between frictional properties and thermal management.

AFM friction image (2 μm × 2 μm) showing a dependence on the different 

structural properties of a patterned substrate.

The AFM is the workhorse instrument for nanoscale friction and 

adhesion measurements; however, even the most advanced AFM lacks 

the ability to perform detailed characterization of thermal properties 

and local thermal profiles in combination with force measurements. By 

integrating Raman spectroscopy with an AFM customized for measuring 

thermal properties, the NRG is building a powerful new measurement 

tool to investigate nanoscale energy dissipation with the potential to 

affect a variety of technologies.

Nanomechanical devices can be used to effectively emulate the sense 

of touch at the nanoscale. Although much has been achieved with 

scanning probe microscopy in its numerous incarnations, there is still a 

great deal to be done to increase the speed and sensitivity with which 

such measurements can be made, and to make those measurements 

with compact devices that can be easily integrated into more complex 

systems. Small-scale mechanical systems can influence and be 

influenced by the intense local fields produced by microphotonic and 

nanoplasmonic structures, allowing for the development of entirely 
3 8 | CNST

novel devices. In a new program that is already yielding exciting results, 

the NRG is creating integrated optical microelectromechanical systems 

(MEMS) with nanoscale elements (NEMS) that will enable imaging, 

metrology, manipulation, and assembly techniques.

Although AFM has proven its utility in nanoscience many times over, 

conventional AFMs are still relatively slow and, because of the freespace optics typically used to detect the cantilever motion, they are 

limited in the combination of spring constants and cantilever dimensions 

that can be used. By integrating the cantilever with a whispering gallery 

resonator the NRG has been able to achieve displacement sensitivities 

of 10-15 m/√Hz in extremely compact devices that have GHz bandwidths. 

As an added benefit, the light is confined in these devices and so does 

not affect the sample under study.

Although increasing the speed of a single probe can yield dramatic 

improvements, using parallel arrays of probes can result in qualitatively 

different measurements. In a new project, the NRG is exploring the 

potential for arrays of near-field optical reference structures to enable 

high-throughput measurements of structures such as photomasks. 

Careful choice of the reference structure geometry with respect to 

the relatively constrained set of patterns on the mask allows the farfield optical signal to provide detailed nanoscale information, once the 

appropriate deconvolution has been performed.

Accomplishments:

•	 Developed an integrated micro-optomechanical system capable 

of high-speed, high-sensitivity displacement measurements for 

scanned probe microscopies.

•	 Revealed the strong influence of applied load and adhesion on 

the frictional properties of graphite, and demonstrated a switch 

in friction contrast between single and multilayer graphene for 

suspended versus supported structures.

Emerging Research:

•	 Measuring nanoscale friction and adhesion.

•	 Developing nanoscale thermal properties characterization by 

combining AFM with local in situ thermometry.

•	 Creating holographic optical tweezers for manipulating 

MEMS and NEMS.

•	 Designing and fabricating optical reference nanostructures for 

high-throughput, near-field optical imaging.

CNST RESEARCH

A cross-sectional illustration of the sample area in the ETEM with integrated 

Raman spectroscopy.
2010 | 3 9

In Situ Measurement—Many of the most important and interesting 

nanoscale phenomena are highly dynamic in nature, and capturing the 

details of these dynamic processes is essential to successfully exploit 

them. Aside from the intrinsic difficulty imposed by the small length 

scale, there are many measurement challenges that arise from the 

environment in which these phenomena occur.

Transmission electron microscopy and its associated analytical 

techniques have proven their value many times over in materials science. 

The NRG is in the process of adding an environmental (scanning) TEM 

[E(S)TEM] to the CNST’s suite of major equipment. This instrument will 

allow for the study of atomic-scale processes occurring, for example, 

during the growth of carbon nanotubes (CNTs) from individual catalyst 

nanoparticles at realistic process temperatures and in relevant gaseous 

environments. The microscope’s capabilities are being enhanced by 

the integration of a custom-built in situ Raman spectroscopy system 

that will enable, for example, the identification of the types of carbon 

nanotubes being formed during growth, or precise local temperature 

measurements. (See Project Highlight, In Situ Measurements of 

Thermodynamics and Reaction Kinetics During Nanomaterials Synthesis 

and Catalysis.) The NRG’s research, leveraging the capabilities of the 

NanoFab, is directed towards the development of new types of sample 

cells that will enable in situ TEM and also SEM measurements of 

bistable electronic switches and electrochemical processes relevant to 

batteries, super capacitors, and fuel cells.

Molecular processes that take place in a liquid environment are 

relevant in biology, but are also important in many self-assembly 

processes. Ensemble measurement techniques can be used to provide 

information integrated over large numbers of individual systems but can 

miss the diversity of behavior that can occur in single events. The NRG 

is focusing on developing methods that can track and interrogate the 

behavior of molecules and nanoparticles as they interact while freely 

diffusing in solution or in proximity to a functionalized surface. We 

have recently developed the models to understand how to control both 

the position and orientation of nanowires in solution using electroosmotic flow and are now experimentally controlling metal, dielectric, 

and semiconducting materials. These methods can be used to control 

and study the interactions of nanoparticles with each other and with 

functionalized surfaces. They may even lead to the development of 

“free-floating” scanned probe techniques that can enable minimally 

perturbative measurements of nanoscale local environments. (See 

the Project Highlight, Particle-Tracking Measurements of Nanoparticle 

Dynamics in Fluids.)

Accomplishments:

•	 Developed the theory of simultaneous object orientation and 

position control.

•	 Demonstrated tracking of individual nanoparticles in three 

dimensions using a microfabricated optical system.

•	 Created improved statistical methods to analyze the behavior of 

diffusing nanoparticles to enable accurate extraction of diffusion 

coefficients.
4 0 | CNST

cost, large-area, high-throughput patterning such as data storage, 

photovoltaics, and batteries. These nanomanufacturing methods 

present unique metrology challenges in terms of monitoring the 

behavior of nanoscale structures at extremely high speeds. The 

NRG’s research in this area is aimed at creating the measurement and 

fabrication methods needed for approaches such as roll-to-roll directed 

self-assembly, which combines existing patterning methods with selforganizing systems like diblock copolymers.

The NRG has developed a resonant-scattering X-ray diffraction technique 

that enables the measurement of the domain profile and interfacial 

roughness of diblock copolymers assembled on lithographically 

patterned substrates. The use of resonant scattering enables the 

generation of high contrast between the two phases of the diblock by 

tuning the X-ray energy to specific chemical bonds. The resulting high 

diffraction efficiency yields data sets with enough resolution to perform 

Emerging Research:

•	 In situ scanning and transmission electron microscopy.

•	 Designing and microfabricating sample environments and 

measurement platforms.

•	 Fluorescence correlation spectroscopy.

•	 Advanced methods to track and interrogate single molecules and 

nanoparticles in real time.

Nanofabrication and Nanomanufacturing—The ability to control 

the detailed configuration of matter at the nanoscale is at the heart 

of nanoscience and nanotechnology. Novel, specialized measurement 

methods and fabrication techniques provide new ways of accessing, 

investigating, and directing nanoscale phenomena. Methods that can 

be scaled for high throughput enable new technological applications of 

these phenomena.

Optical lithography is still the mainstay of the current major 

nanomanufacturing industry—integrated circuit (IC) fabrication—

and is likely to be so for the foreseeable future. However, in order 

to maintain the current rate of progress, continuous improvements in 

the lithographic process must be made. These improvements depend 

on developing an ever more detailed understanding of nanoscale 

stochastic and molecular effects. The NRG is focused on creating 

the measurement methods that are needed to extend the lifetime and 

applicability of these existing techniques. (See the Project Highlight, 

The Effect of Resist on the Transfer of Line-Edge Roughness Spatial 

Metrics from Mask to Wafer.)

In a new research effort, the NRG is applying the technique of 

photoactivated localization microscopy (PALM) to map the distribution 

of acid catalyst species in chemically amplified resist materials. The 

acid catalysts enable each photon incident during the exposure process 

to cause a significant chemical change. This change increases the speed 

of the photoresist, but the acid diffusion that occurs can compromise 

the resolution. Until now, there has been no way of monitoring this 

process, with the acid behavior only inferred from the latent or 

developed image. The NRG has been able to perform measurements 

of the acid-diffusion blur using very dilute concentrations of fluorescent 

molecules (which therefore do not affect the resist). The technique 

works by recognizing that knowledge of the initial lithographic pattern 

functions as a maximum likelihood estimator for the acid-diffusion blur. 

In this way, a very sparse sampling of the diffusion profile can still yield 

nanometer-scale accuracy and precision. This technique may also be 

applicable to systems such as lithium-ion batteries, where detailed 

knowledge of ion distributions is important.

Novel fabrication techniques that do not have the same overlay and 

defectivity requirements as those used in integrated circuit production 

will address new applications; in particular, those that require lowCNST RESEARCH
2010 | 4 1

detailed parameter extraction with high confidence. (See the Project 

Highlight, Line-Edge Roughness Measurements in Diblock Copolymers.)

The precise assembly of nanoscale components represents one of the 

major challenges in nanomanufacturing. Molecular assembly methods 

based on DNA are gaining in popularity because of their ability to 

produce well-defined and highly-functional architectures. In another 

new project, the NRG is developing ways to measure the yield and 

speed of nanoparticle assembly on DNA origami. The measurements 

provide insight into the design rule constraints that apply to these kinds 

of processes and will serve as a guide to those attempting to create 

manufacturable devices based on this type of directed self-assembly.

AFM images of quantum dot nanopatterns on DNA origami templates. The 

cartoon illustrates the locations of the binding sites for this origami design, 

with successful self-assembly demonstrated by the two higher magnification 

images of individual templates, each with quantum dots decorating all four 

corners.

Accomplishments:

•	 Applied novel estimators for characterizing a particle control 

system to enable the deposition of single quantum dots to an 

accuracy of less than 50 nm.

•	 Developed a resonant X-ray scattering technique to measure 

the detailed domain shape and interfacial roughness in diblock 

copolymers assembled on lithographic patterns.

Emerging Research:

•	 Metrology for high-throughput nanomanufacturing.

•	 Stochastics of nanoscale systems.

•	 Directed assembly of diblock copolymers.

•	 Molecularly-precise, templated assembly. 

•	 Super-resolution optical imaging for lithographic process analysis.

•	 Nanoparticle tracking for inter-particle force measurements. 

•	 Active control of nanoparticle assembly. 

•	 Focused-ion beam nanofabrication, analysis, and metrology.
PROJECT HIGHLIGHTS

4 2 | CNST

High resolution Landau level spectroscopy of the four-fold states that make 

up the N=1 Landau level (LL) at different applied magnetic fields. At fields of 

11.125 T, 11.375 T, and 14 T, new half-filled quantum states are observed at 

filling factors 11/2, 9/2, and 7/2 respectively. The electron spin splitting is 

enhanced at the odd filling factor of 5 at 11.25 T, while the valley splitting is 

enhanced at filling factor 4 at 11.75 T

field. These are the first measurements from the recently constructed 

ultra-low temperature scanning probe microscopy system at the CNST, 

and are the lowest temperature scanning probe measurements ever 

performed. 

Results and Discussion: We measured the tunneling spectra of 

epitaxially grown graphene on the carbon face of SiC as a function 

of magnetic field at 13 mK. The spectra showed the evolution of 

the Landau levels with magnetic field. The field dependence of the 

orbital quantum number determined the graphene carrier velocity and 

demonstrated single layer graphene electronic behavior. This results 

from the multilayer graphene film being electronically decoupled due to 

the small rotational misalignments between the layers.

With the higher energy resolution obtained at these temperatures, the 

spectra showed interesting features relating to energy splitting within 

a single Landau level. The single N1 Landau level was observed to be 

10In order to provide a more complete overview of the breadth of 

activities supported by the CNST as a national User Facility, the following 

pages provide more in-depth highlights of a selection of projects. These 

projects represent a cross-section of measurement research conducted 

by the CNST staff, along with projects in the NanoFab led by academic, 

industrial, and NIST researchers.

Measuring Quantum Electronic Properties 

of Graphene

Research Participants: Y. J. Song,1,2 A. F. Otte,1,2 Y. Kuk,1 Y. Hu,3

D. B. Torrance,3 P. N. First,3 W. A. de Heer,3 H. Min,1,2 S. Adam,1 M. D. 

Stiles,1 A. H. MacDonald,4 and J. A. Stroscio1

1

Center for Nanoscale Science and Technology, NIST, Gaithersburg, 

MD 20899

2

Maryland NanoCenter, University of Maryland, College Park, MD 

20742

3

School of Physics, Georgia Institute of Technology, Atlanta, GA 30332

4

Department of Physics, University of Texas at Austin, Austin, TX 

78712

Key Accomplishments:

•	 Resolved the “quartet” electronic structure of graphene magnetic 

quantum states.

•	 Discovered new fractional many body quantum states in 

graphene.

Background: Graphene, a single atomic layer sheet of carbon, has 

unique electronic properties with potential applications in future 

electronics, sensors, and composite materials. Electrons in graphene 

behave quite differently from those in traditional 2D electron systems. 

Like massless relativistic particles, they have linear dispersion and 

chiral eigenstates. In addition, there are two sets of electrons that have 

this dispersion centered at different valleys in reciprocal space. The 

symmetry between valleys, together with the two possible spin states, 

leads to a four-fold degeneracy of the Landau levels. Understanding 

how electron-electron interactions lift the degeneracies in graphene’s 

electronic states has been an intense goal in graphene research, 

with quantitative measurement of these interactions important for 

future applications. The main experimental methods for investigating 

these issues have been electrical transport measurements. Because 

graphene is an exposed 2D electron system, low-temperature scanning 

probe measurements offer an opportunity to probe the electronic 

structure of graphene with atomic-scale spatial resolution, thereby 

measuring the local variations in properties that are typically averaged 

over by traditional transport measurements.

Approach: We apply scanning tunneling spectroscopy at milli-Kelvin 

temperatures to resolve the graphene “quartet” electronic structure 

of magnetically quantized states and directly measure the energy 

separations when the degeneracies are lifted in an applied magnetic

Project Highlights
Project Goal: To develop a microscopic understanding of the 

scattering processes and localization phenomena determining 

the metrology-relevant half-integer quantum Hall effect of Dirac 

fermions and defining the transport properties of graphene devices 

for future electronic applications.

Key Accomplishments:

•	 Developed a fabrication process for graphene devices that 

maintains the high-degree of surface cleanliness required 

for STM experiments.

•	 Measured the evolution of scattering and localization using 

scanning tunneling spectroscopy in an applied magnetic 

field.

Background: Graphene is a unique two-dimensional material 

whose emerging physical properties hold great promise for 

electronic device applications. In realistic devices, physical 

phenomena such as the half-integer quantum Hall effect and 

high carrier mobility depend on interactions with impurities 

and substrates and on the localization of Dirac fermions. For 

example, plateaus in the quantum Hall effect are caused by the 

carrier localization, but very disordered samples do not display 

the effect at all. While achievable carrier mobility in graphene is 

extraordinary high, the mobility in research devices is much lower 

because of difficulties of integration and unintended disorder. 

Fortunately, direct access to a tunable exposed two-dimensional 

electronic system of Dirac fermions in graphene by scanning probes 

allows for the measurement of these carrier interactions and of the 

localization in greater detail than in conventional semiconductor 

devices, where the carrier transport layers are buried below the 

surface.

Approach: To avoid possible contamination caused by 

conventional wet-chemistry processing, graphene devices were 

fabricated from pristine flakes exfoliated on a SiO2

 substrate using 

stencil masks. Scanning tunneling spectroscopy (STS) was used 

to measure the local tunnel current-voltage (I-V) curves at a fixed 

distance between the tip and the sample. In these measurements, 

2010 | 4 3

split into four sub-levels due to the lifting of the electron spin and valley 

degeneracies. When the Fermi level lies inside the four-fold Landau 

manifold, significant electron correlation effects result in an enhanced 

valley splitting at even filling factors, and an enhanced electron spin 

splitting at odd filling factors. Between integer filling factors, we 

discovered a series of new fractionally filled levels at filling factors of 

7/2, 9/2, and 11/2. These measurements, which resolve spectroscopic 

features which are enhanced and fractional, suggest that new many 

body quantum states occur under these extreme conditions of ultra-low 

temperatures and high magnetic fields.

Recent Publications:

High-resolution tunnelling spectroscopy of a graphene quartet, Y. J. 

Song, A. F. Otte, Y. Kuk, Y. Hu, D. B. Torrance, P. N. First, W. A. de Heer, 

H. Min, S. Adam, M. D. Stiles, A. H. MacDonald, and J. A. Stroscio, 

Nature 467, 185-189 (2010).

Real-space mapping of magnetically quantized graphene states, 

D. L. Miller, K. D. Kubista, G. M. Rutter, M. Ruan, W. A. de Heer, M. 

Kindermann, P. N. First, and J. A. Stroscio, Nature Physics 6, 811-817

(2010).

A 10 mK scanning probe microscopy facility, Y. J. Song, A. F. Otte, V. 

Shvarts, Z. Zhao, Y. Kuk, S. R. Blankenship, A. Band, F. M. Hess, and J. 

A. Stroscio, Review of Scientific Instruments 81, 121101 (2011).

Localization in Graphene Devices Probed 

by STM

Research Participants: S. Jung,1,2 G. M. Rutter,1 N. N. Klimov,1-3 D. 

B. Newell,3 I. Calizo,3 A. R. Hight-Walker,3 N. B. Zhitenev,1 and J. A. 

Stroscio1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Maryland Nanocenter, University of Maryland, College Park, MD 

20742

3

Physical Measurement Laboratory, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

(a) Tunneling spectra at different gate voltages combined 

in a “gate map” at 8 T. The dI/dV curves taken at different 

gate voltages are color-coded (white corresponds to 

peaks in the conductance) and plotted vertically with the 

horizontal shift proportional to the gate voltage. Two 

sets of features are seen in the map: the “horizontal” 

peaks are the Landau levels, and groups of “vertical” 

peaks result from single-electron charging of the QDs. (b) 

The tunneling current is defined by the density of states 

between the Fermi energy (EF ) of the tip and the sample. 

Tunneling channels at EF of the tip are seen as horizontal 

lines in the gate map, while the channels at EF of the 

sample appear as vertical lines.
PROJECT HIGHLIGHTS

4 4 | CNST 

Development of Si-Based Single-Electron 

Devices (SEDs) for a Fundamental 

Current Standard and for Quantum

Information 

Research Participants: M. J. Stewart,1,2 J. Bowser,3 and N. M. 

Zimmerman1

1

Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899

2

Joint Quantum Institute, University of Maryland, College Park, 

MD 20742

3

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

Project Goal: To develop Si-based single-electron devices, 

based on the Coulomb blockade, for applications in a fundamental 

electrical current standard based on the charge of the electron, and 

in charge or spin qubits for quantum computing.

Key Accomplishments:

•	 Designed and implemented a process flow for SOI (siliconon-insulator) MOSFETs, integrating ion implantation, polySi 

deposition, doping and patterning, and contact to metal 

leads.

•	 Demonstrated up to factor of 107 in on-off current ratio.

Background: Single-electron devices (SEDs) offer the amazing 

ability to move electrons around one-by-one. We have two longterm goals for our project. The first goal is the development of a 

quantum current standard. If we can develop a current standard 

based on the value of the electron charge, e, we could test Ohm’s 

law with all three parameters being based on fundamental 

constants of nature; however, we need a standard with a current 

value of at least 100 pA, which is much larger than presently 

available. Si-based SEDs (essentially nanoscale MOSFETs with 

multiple gate layers) offer two potential advantages in this 

regard: higher operation frequency, and the ability to parallelize 

multiple devices. The second goal is to develop SEDs for quantum 

coherence applications. Many different experimental approaches 

are being pursued to develop a usable quantum computer. One 

main approach is semiconductor-based quantum dots, with the 

quantum mechanical degree of freedom being either charge 

position or electron/nuclear spin direction. In this approach, 

one important real-world source of undesirable decoherence is 

defect-mediated charge noise in the surrounding material. Our 

planed approach to addressing this problem is to fabricate highquality devices with low defect density and then perform both 

decoherence (T1

 and T2 times) and standard Si microelectronics 

industry measurements; e.g., C-V, G-V, DLTS, ESR, SDR, etc. In 

this way we hope to elucidate the sources of decoherence and 

their coupling mechanisms in order to ameliorate or eliminate this 

problem.

the differential conductance, dI/dV, is proportional to the local density 

of states. Controlling the charge density of the Dirac fermions using 

an electrostatic back gate, we investigated the local density of states 

and localization in graphene at the atomic scale while varying the Fermi 

energy (EF ) with respect to the charge neutral Dirac point (ED

). Varying the 

magnetic field from zero to the quantum Hall regime strongly affected 

the electronic behavior of the graphene, and the states condensed into 

well-defined Landau levels with dramatic changes in the localization.

Results and Discussion: In an ideal graphene layer, the carrier 

density can be continuously tuned from hole to electron doping, through 

zero density at ED. Local disorder gives rise to a spatially varying 

electrostatic potential that changes the relative position of ED with 

respect to EF. If EF is close to ED, then spatially alternating patterns of 

electron and hole puddles are formed. The distribution of the density 

set by the back gate voltage and spatially modulated by the disorder 

potential can be determined by locating ED, a local minimum of the 

differential conductance dI/dV. 

At zero magnetic field, we mapped the density fluctuations arising from 

the disorder potential variations. We found resonances in the density 

of states associated with the scattering from the disorder potential, 

as supported by the correlation between the spatial properties of the 

disorder potential and the spatial variation of the resonances.

At higher magnetic fields, discrete Landau levels (LLs) were resolved 

with both electron and hole states following single-layer graphene 

scaling. The LL spectra were dramatically different from previous STS 

measurements of epitaxial graphene on SiC and of graphene flakes on 

graphite, which showed characteristics of weakly disordered systems. 

Besides broader LLs due to disorder, we observed an additional set of 

localization resonances in the tunneling spectra governed by single 

electron charging effects. Effectively, the localization in graphene 

can create local quantum dots (QDs) with current flowing through 

two tunnel barriers in series: the vacuum tunnel barrier between the 

probe tip and a local graphene QD, and a barrier originating from the 

resistive incompressible strips that isolate the QD in a high magnetic 

field. Therefore, our STS measurements not only detect local density 

of states variations in graphene with and without magnetic fields, but 

also measure the electronic structure with sufficient sensitivity to probe 

single-electron charging phenomena at the Fermi level.

Recent Publications:

Evolution of microscopic localization in graphene in a magnetic field: 

from scattering resonances to quantum dots, S. Jung, G. M. Rutter, N. 

N. Klimov, D. B. Newell, I. Calizo, A. R. Hight-Walker, N. B. Zhitenev, and 

J. A. Stroscio, Nature Physics 7, 245-251 (2011).
Recent Publications:

Quantum electrical standards, N. M. Zimmerman, Physics Today

63, 68 (2008).

Lack of charge offset drift is a robust property of Si single electron 

transistors, E.l Hourdakis, J. A. Wahl, and N. M. Zimmerman, 

Applied Physics Letters 92, 062102 (2008).

Laser Direct Write to Enhance Inter-Chip 

IO Bandwidth

Research Participants: R. R. Yu, E. G. Colgan, S. 

Purushothaman, D. S. Nielsen, R. Wisnieff, and M. M. Denneau

IBM Watson Research center, 1101 Kichanwan Road, Route 124, 

Yorktown Heights, NY 10598

Project Goal: The goal is to develop a characterization 

methodology for inter-chip input/output (IO) positional variability 

in highly integrated composite wafer substrates. This includes 

developing methods for IO positional correction and IO density 

enhancement by pattern recognition using laser direct writing 

(LDR). The intent is to apply this research to future manufacturing 

processes.

Key Accomplishments:

•	 Substrate characterization results met target.

•	 Pattern recognition and laser direct write met requirements.

•	 Laser direct writing achieved better resolution than monolith.

•	 Square substrate demonstrated improved process-ability.

Background: Since 2004 device parallelism scaling (multicores) has replaced frequency scaling for performance gains in 

chips within a relatively stable operating system clock frequency 

range. Several options are currently being actively pursued to 

increase this parallelism through system integration methods, 

such as 3D integration (3DI) and system-in-package (SIP). These 

are alternatives that provide higher system contents in both logic 

cores and memories than the traditional system-on-chip (SOC) 

configuration. Structures with high contents in close proximity 

are of particular interests for super systems aimed at exa-scale 

computing where a large number of logic cores require an 

even larger number of supportive memories which are difficult 

to achieve with SOC on a planar configuration. One of the key 

development goals for a composite system like 3DI and SIP is the 

IO bandwidth enhancement between the component wafers. In 

SOC the IO are well defined and optimized. With integrations, a 

large number of component device wafers are brought together 

from different wafer sources to form a composite substrate as a 

hybrid system. The variations in each component wafer in the 

composite substrates are magnified and make it difficult to form 

the required fine pitch IO connections between the component 

2010 | 4 5

Approach: A schematic of one of our devices fabricated in the CNST 

NanoFab is shown in the figure. The device consists of the following 

three basic parts: a mesa-etched single crystal Si wire on a SOI wafer; 

two separate layers of doped polySi gates, with gate oxide and isolation 

oxides; and ion-implanted source and drain regions with metallization 

on the front and back surfaces. The fabrication process flow requires 

between 60 and 80 individual steps, requiring the overall reliability and 

yield performance maintained in the NanoFab.

The basic electrical operation of the device is as follows. For these 

enhancement-mode devices, the upper gate, which extends from the 

source to the drain, is biased positive to turn on overall conduction. The 

lower “finger” gates are biased negative in order to inhibit conduction 

underneath the individual fingers. The combination of these biases 

forms conducting regions separated at low temperatures by tunnel 

barriers, such that individual electrons have to quantum-mechanically 

tunnel from one conducting region (quantum dot) to another. Because 

of the Coulomb blockade, electron flow on or off the dot in these regions 

is quantized in units of 1 e, and therefore can be made into a current 

standard. By trapping one or two electrons localized on one or both of 

the dots, we can start to perform quantum-mechanical manipulations; 

for instance, by looking for the signature of a quantum coherent 

oscillation of the position of the electron between the two dots.

Schematic of a full device, including a mesa-etched SOI wire (gray), 

lower finger gates (aqua), upper gate (blue), source/drain (purple), and 

metallization (green). The MOSFET control curve is shown as a semi-log 

plot of current versus gate voltage for a device with no lower gates, and 

exhibits a 104 turn-on ratio.

Results and Discussion: Having started the development of the 

process about one year ago, we have refined choices for many of 

the individual process steps, and completed some of the block tests. 

Fabricating the MOSFET block tested the integration of oxide and polySi 

growth, large (not nm scale) gate patterning, source and drain implant 

and activation, and metallization. The graph shows good subthreshold 

slope over a factor of about 104. The Si nanoscale patterning block test 

gave us the ability to combine negative tone electron beam lithography 

with dry etching. By going from a fluorine-based to a chlorine-based 

chemistry, we have been able to achieve this combination.
PROJECT HIGHLIGHTS

4 6 | CNST 

format used in the early builds for the better topography, the ease 

of handling, and for the higher area utilization and design plan for 

the devices. Based on the structural scan results, a correction 

factor is uniquely generated for each IO and is directly written to 

the IO to make the connective offsets for all IO and lead the IO to 

the new locations, which are located in the ideal design positions. 

Because each IO offset is different, a large number of scans and 

re-directs are needed for the entire substrate. The scan results 

also help us to identify previously unknown substrate variations, 

such as the size difference between the design data and the actual 

wafer images between different tool sets, and the positional shift 

due to the image quality. All these variabilities affected the early 

work and limited the required IO density; these limitations are 

being remedied with direct write. As a result, the IO resolution 

has improved by three times with the 20 mm writing heads as 

compared with the early monolithic lithography. The direct write 

also enables us to use square format substrates, resulting in a 

significant improvement in surface planarity. It is expected that 

with further learning, the substrate quality and the IO resolution 

can be further improved to the levels of SOC BEOL.

Acknowledgments: We offer special acknowledgement to 

G. Shahidi for his management support. Contributions are also 

acknowledged from M. Cangemi and R. Kasica in the NanoFab, 

and from P. Sorce, J. Pogemiller, A. Prabhakar, and B. Fletcher of 

IBM. This work was supported in part by the US government under 

the contract.

Measurement of Current Polarization by 

Doppler-Shifted Spin Waves

Research Participants: M. Zhu,1,2 C. L. Dennis,3 B. D. Soe,4 M. 

J. Carey,5 S. Maat,5 J. R. Childress,5 R. Thomas,6 V. Misra,6 and 

R. D. McMichael1

1

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

2

Maryland Nanocenter, University of Maryland, College Park, MD 

20742

3

Material Measurement Laboratory, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

4

Department of Engineering, Harvey Mudd College, Claremont, CA 

91711

5

San Jose Research Center, Hitachi Global Storage Technologies, 

San Jose, CA 95135

6

Electrical and Computer Engineering, North Carolina State 

University Raleigh, NC 27695

Project Goal: To develop methods for measuring the spin 

polarization of current in ferromagnetic metals, an often-estimated 

materials parameter that plays a pivotal role in the spin-torque 

driven dynamics of magnetic nanodevices.

wafers with a monolithic lithography. This difficulty reduces the IO 

density. In this study, laser direct write is being evaluated as a mean to 

re-write the IO connections in the substrates to enhance the IO density 

in a highly integrated composite system.

Approach: In this work we are evaluating structures that have higher 

multiple contents than the standard SOC density and are assembled into 

square substrates which themselves are each a composite assembly 

of many wafers. Each wafer contains various structural variabilities 

that occur in different process stages and during substrate assembly. 

These structural variabilities include those due to processing, overlay 

tolerance, wafer thinning, wafer dicing, and substrate assembly. The 

test structure contains various IO pitches which are first overlaid with 

images by monolithic lithography. The standard monolithic lithography 

is insufficient for our application needs. The same structure is then 

scanned using the NanoFab Heidelberg laser direct write pattern 

recognition system to locate the IO and to record the offsets of the IO 

from the design positions. The measured offsets are fed into the laser 

write file to make the necessary correction for each IO and re-direct the 

IO to the new, ideal locations. The IOs are then again imaged with the 

monolithic lithography to the new locations and the IO pitch density is 

evaluated for pitch density improvement.

(a) Some 3DI and SIP options identified in ExaScale Computing Study: 

Technology Challenges in Achieving Exascale Systems (DARPA/IPTO, 2008). (b) 

Resolution improvement shown by comparing monolithic lithography (top) with 

laser direct write (bottom).

Results and Discussion: For a full field exposure, the Heidelberg 

laser writer offers several writing head options for various writing-field 

areas. The highest resolution is the 2 mm head with 0.6 μm lines at 

1.2 μm spacing with a small writing field. At the lowest end is the 20 

mm write head with 4 μm lines at 8 μm spacing with a much larger 

writing field. There is a trade-off between the write speed and the 

write resolution. We select the maximum write field (20 mm head) 

for our substrate due to the production throughput consideration. The 

substrates are first scanned for their positional accuracy using the 

patterning recognition feature in the Heidelberg tool. This data allows 

us to characterize and improve our assembly method. We are able 

to identify at this stage the impact of substrate format on the planar 

resolution. The square format substrate is then selected over the round 
the polarization of the current by observing the effect of the 

magnetization drift velocity on the propagation of spin waves 

in magnetic wires. A pair of antennas with periodic structures 

launches and detects the spin waves while fixing their wavelength. 

A peak in the transmission between the antennas determines the 

spin wave frequency, which is Doppler shifted by the magnetization 

drift velocity.

Results and Discussion: Our initial measurements were 

performed on Ni80Fe20, where we measured Doppler shifts 

corresponding to drift velocities on the order of 4 m/s in current 

densities of 1011 A/m2. Using a cryogenic probe station with an 

integrated electromagnet and both microwave and DC probes, we 

measure the Doppler shift of the spin wave frequency to obtain the 

drift velocity and the current polarization. Our room-temperature 

polarization value of P = 0.58 ± 0.02 is in fair agreement with an 

independent spin wave Doppler measurement. Between 340 K 

and 80 K, the polarization increases to 0.75 ± 0.05, trending toward 

values obtained by earlier analysis of current-perpendicular 

transport measurements at 4.2 K.

Our second set of experiments, done in collaboration with 

Hitachi GST, measured the current polarization in (CoFe)1-xGex

alloys. These alloys exhibit many of the properties of half-metal 

Heusler alloys such as high polarization and low damping. They 

are potentially useful for manufacturing applications because 

they require annealing at a modest temperature of 245 C that is 

compatible with established fabrication processes. We found that 

for increasing Ge concentrations in the range of 0.0 < x < 0.3, the 

reduced magnetization causes the drift velocity to increase from 

3.1 ± 0.2 m/s to 8.2 ± 0.6 m/s at a current density of 1011 A/m2, but 

that the polarization increases from 0.84 ± 0.04 at x = 0.0 to a broad 

maximum of 0.95 ± 0.05 at x = 0.25. These results are consistent 

with the first-principles predictions of a pseudogap or low density 

of states in the down-spin band.

Acknowledgments: This work has been supported in part by the 

National Science Foundation.

Recent Publications:

Temperature dependence of magnetization drift velocity and current 

polarization in Ni80

Fe20 by Spin-Wave Doppler Measurements, M. 

Zhu, C. L. Dennis, and R. D. McMichael, Physical Review B 81, 

140407 (2010).

Enhanced magnetization drift velocity and current polarization in 

CoFe1−xGex alloys, M. Zhu, B. D. Soe, R. D. McMichael, M. J. Carey, 

S. Maat, and J. R. Childress, Applied Physics Letters 98, 072510 

(2011).

2010 | 4 7

Key Accomplishments: 

•	 Designed and fabricated devices to measure spin wave 

propagation at sub-μm wavelengths in current-carrying 

ferromagnetic metals.

•	 Measured current polarization in Ni80Fe20 (Permalloy) with two 

times the precision of existing measurements, and provided 

the first measurements of temperature dependence in current 

polarization.

Background: Spin-polarized current provides an important and 

relatively new mechanism for changing the direction of magnetization 

in novel nanodevices. Spin-polarized current transports spin angular 

momentum that exerts a “spin transfer torque” on magnetization, 

providing a low-power alternative to Ampere’s-Law fields for flipping 

“bits” in novel nonvolatile memory technologies, such as MRAM and 

racetrack memory. The current polarization, P, quantifies the relative 

magnitude of the currents carried by up-spin and down-spin electrons. 

Despite its importance, until now, measurements of P have been 

primarily limited to interface-sensitive and low-temperature techniques.

False color SEM image of a spin wave Doppler device. The central red stripe is 

a Ni80

Fe20 (Permalloy) magnetic metal wire. DC contacts at the ends of the wire 

in yellow inject current and allow voltage measurements. Curved triple lines 

are coplanar microwave waveguides connected to antennas. The inset is an 

expanded view of the antennas that launch and detect spin waves showing the 

periodic structure that determines the spin wave wavelength. A dielectric layer, 

shown in blue, insulates the antennas from the wire.

Approach: The magnetic moments of up and down spin electrons 

are proportional to their angular momentum. Therefore, spin-polarized 

currents transport both angular momentum and magnetization. In fact, 

in the limit where the current polarization direction is parallel to the local 

magnetization, the magnetization in a long, uniform wire should behave 

exactly as if the magnetization were being carried “downstream” by 

the electron current at a drift velocity that is proportional to both the 

current density and the polarization, but inversely proportional to the 

magnetization. In the spin-wave Doppler measurements, we measure 
PROJECT HIGHLIGHTS

4 8 | CNST

Background: Magnetic bits store most of the world’s information, 

either in magnetic tapes or in hard disk drives. Magnetic materials 

are excellent for storing information because in a small volume, 

the magnetization typically points in one direction (which can 

signify a “1”) or its opposite (which can signify a “0”) and will stay 

in that state unless power is applied. With the semiconductor 

road map rapidly approaching difficult physical limits, there is 

significant effort to develop new ways of storing and processing 

information. One of the most recent approaches is to store 

information in magnetic domains in wires made of ferromagnetic 

materials. Magnetic domains are regions of a sample in which 

the magnetization is uniform. Domains are separated from each 

other by domain walls. Manipulating magnetic domains for 

storing information revives an old technology – magnetic bubble 

memory, but with a new twist. When a magnetic wire gets small 

enough, it becomes possible to move the domains, or rather the 

walls between the domains, by running a current through the wire 

rather than by applying a magnetic field. This new approach scales 

better to lower sizes and raises the possibility of high density, nonvolatile, and fast memory. Designing such devices requires the 

ability to measure the appropriate material properties. 

Approach: We take a theoretical approach to understanding 

domain wall motion. In particular, we use calculations to facilitate 

the interpretation of measurements. There have been a number of 

measurements of domain wall motion driven by current. Typically 

the experiments measure the domain wall velocity as a function of 

the current and an applied magnetic field. These measurements 

are then interpreted in terms of models of domain wall motion 

in idealized magnetic wires. However, imperfections have a 

strong effect on the motion and therefore on the interpretation 

of the experimental results. To understand the consequences of 

disorder on the measurement, we have carried out micromagnetic 

simulations of domain wall propagation and developed simpler 

models to interpret the results in a framework that can be used to 

interpret experiments. Micromagnetic simulations are based on a 

continuum description of magnetic materials on an intermediate 

length scale. We use the Object Oriented MicroMagnetic 

Framework, software developed at NIST, for the simulations and 

run them on a Beowulf cluster at NIST. We analyze the results of 

the simulation using a model in which all the details of the domain 

wall are reduced to two numbers giving the wall’s position in the 

wire.

Results and Discussion: For a domain wall to move down the 

length of a wire due to an applied magnetic field, the magnetic 

system has to lose energy to the lattice. If there were no energy 

loss, the domain wall would just oscillate without making any 

forward progress. The figure shows how energy loss near the 

vortex core allows the wall to move forward.

The Effect of Disorder on Magnetic 

Dynamics

Research Participants: H. Min,1,2 R. D. McMichael,1 M. J. Donahue,3

J. Miltat,1,2,4 and M. D. Stiles1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Maryland NanoCenter, University of Maryland, College Park, MD 

20742

3

Information Technology Laboratory, National Institute of Standards 

and Technology, Gaithersburg, MD 20899

4

Laboratoire de Physique des Solides, Université Paris Sud, CNRS, 

UMR 8502, 91405 Orsay, France

Project Goal: To determine the extent to which disorder can confound 

the determination of material properties through measurements of 

magnetic domain wall motion.

Key Accomplishments:

•	 Simulated vortex wall propagation in a disorder magnetic wire 

and showed how the results could be interpreted as an increase 

in the effective damping.

•	 Determined that similar effects are much smaller for the vortex 

gyration in a magnetic disk.

•	

•	

Calculation of the energy dissipation during vortex domain wall motion. 

The magnetic configuration of a vortex wall is shown in the upper left. The 

magnetization curls around a vortex. When a magnetic field is applied, the 

domain wall moves down the wire while oscillating from side to side. This 

motion is shown in the upper right in the location of the vortex core as the wall 

moves. The wall moves from side to side where the core collides with the edge 

of the wire and then it reverses direction and moves back. Without energy loss, 

the wall would simply oscillate in place. The main panel shows the energy loss 

as a function of time and position along the wire. The energy loss is localized 

around the vortex core.
2010 | 4 9

•	 A planarization technique to remove the topographically 

uneven surface configuration of magnetic island arrays has 

also been demonstrated, which eliminates the magnetic 

material outside the pillar top bit locations to reduce 

magnetic signal interference, and also to allow the read/

write recording head to easily fly on the hard disk media 

surface.

Background: Significant advances have been made in recent 

years in the field of nanomaterials and nanodevices, with their 

size scales continuing to decrease. While exciting nanomaterials 

concepts have been demonstrated with carbon nanotubes, 

semiconductor nanowires, quantum dot particles, and so forth, 

the progress toward large scale integration of these materials 

and devices into useful electronic devices and system arrays has 

been rather slow, largely due to the lack of industrially viable and 

efficient nanofabrication techniques. For hard disk drive magnetic 

recording, one of the key components in computer technologies, 

a storage density of 1 Tb/in2

 or higher (approximately five times 

current hard disk drive media) is desired, and a viable fabrication 

technique is needed to achieve this density.

SEM images showing fabrication of bits at 1.6 Tb/in2 by (a) electron 

beam patterning of HSQ resist at 20 nm pitch and (b) Si pillar array from 

the exposed HSQ created by RIE pattern transfer, with pillars 10 nm in 

diameter and 20 nm high.

Approach: In order to accomplish such a large memory density, 

bit-patterned media having periodically spaced islands of magnetic 

recording material are preferred because the undesirable magnetic 

interaction between adjacent bits and associated reduction in 

signal-to-noise ratio can be minimized. To obtain such a high 

density memory, advanced electron beam lithography is used and 

the pattern transferred to form periodic silicon pillar arrays. The 

behavior of magnetic islands deposited on the pillar top is also 

investigated. Furthermore, planarization of topographically uneven 

features has been achieved using SiO2 filling of the valley space, 

to obtain cleaner magnetic signals and read/write head flyability 

from the hard disk surface.

Repeating the calculation in the presence of disorder generates an 

important caveat to the interpretation of such experiments. We find 

that when the vortex core and other sharp features of the vortex 

structure move through the disorder, the wall gets excited and loses 

energy faster. Since the wall loses energy faster, it moves down the 

wire more rapidly, giving the counterintuitive result that, up to a limit, 

the wall moves faster the more disorder there is in the wire. It turns 

out to be possible to analyze this behavior using a simple description 

in terms of an increased effective damping. The fact that the intrinsic 

damping in the system can differ significantly from the value that would 

be interpreted from experiment is important both for the analysis of 

experiments and for the design of devices.

Recent Publications: 

Effects of disorder and internal dynamics on vortex wall propagation, H. 

Min, R. D. McMichael, M. J. Donahue, J. Miltat, and M. D. Stiles, Phys. 

Rev. Lett. 104, 217201 (2010).

Effects of disorder on magnetic vortex gyration, H. Min, R. D. McMichael, 

J. Miltat, and M. D. Stiles, Physical Review B 83, 064411 (2011).

Ultra-High-Density Patterned Magnetic 

Recording Media

Research Participants: E. C. Choi,1,2 M. Young Oh,1,2 S. Jin,1,2 R. 

Kasica3, and L. Chen3

1

Materials Science and Engineering, University of California, 

San Diego, La Jolla, CA 92093

2

Center for Magnetic Recording Research, University of California, 

San Diego, La Jolla, CA 92093

3

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

Project Goal: The ultimate objective of this project is to develop 

large-area, nanoimprint lithography techniques for applications such 

as ultra-high-density, patterned magnetic recording media with at least 

1 terabit per square inch (Tb/in2) recording density—about five times 

higher than the current hard disk memory in the market. Such a high 

recording density requires patterned media with a recorded magnetic 

island bit size of ≈12.5 nm in diameter or smaller, arranged in a periodic 

fashion.

Key Accomplishments:

•	 Nano-patterning of a Si substrate and patterned island formation 

with a bit density as high as 1.6 Tb/in2 has been accomplished 

in the CNST NanoFab using electron beam lithography and 

nanoimprinting. A bit size on the order of 10 nm in diameter 

has been achieved with a spacing of similar dimension. The 

magnetic switching behavior of patterned bit islands of (CoPd)n

perpendicular anisotropy magnets has been investigated.
PROJECT HIGHLIGHTS

5 0 | CNST 

Background: Spintronic logic presents an exciting magnetic 

alternative to traditional CMOS-based transistor logic. The 

magnetic quantum cellular automata (MQCA) approach is a leading 

candidate for this type of magnetic switch. A bit is represented 

using 4 magnetic nanopillars in a square array. There are two 

possible minimum energy ground states for this system, with one 

state representing a ‘0’ and the other a ‘1’. Our work attempts to 

develop an MQCA system using CoFe2O4 (CFO) for the magnetic 

pillars because of its potential as a magnetoelectric material—a 

material whose magnetic moment can be controlled using an 

electric field.

Approach: CFO thin films were deposited on MgO and SrTiO3

single crystal substrates using a pulsed electron deposition (PED) 

system at the University of Virginia (UVA). A Si capping layer 

was deposited on the surface of the CFO films via radio frequency 

(RF) sputtering in the CNST NanoFab to promote resist adhesion 

and for use as a sacrificial mask during etching. Electron beam 

lithography (EBL) was performed using hydrosilsesquioxane (HSQ) 

as a negative-tone electron beam resist with the NanoFab’s Vistec 

EBL system. The samples were then etched using the Cl2 ICP/

RIE system to selectively remove the Si layer in the unexposed 

areas, leaving nanopillars in the area where the HSQ resist was 

exposed. An Ar mill was performed to etch through the CFO film 

to the substrate to transfer the nanopillar pattern into the film. 

The resulting CFO nanopillars were then characterized using a 

magnetic force microscope (MFM) system at UVA to measure the 

effects of dipole coupling between neighboring pillars.

(a) AFM and (b) corresponding MFM image of CFO nanopillar array. Pillar 

heights are approximately 35 nm above the surface, with diameters 

of approximately 75 nm and a pitch of 200 nm between the center of 

neighboring pillars. The MFM image shows magnetic contrast from the 

pillars, the first such demonstration. There is also evidence of magnetic 

dipole interactions between the pillars in some cases, which is a good 

first step towards the eventual goal of achieving an MQCA system.

Results and Discussion: The films were successfully grown in 

the PED system at UVA and were characterized to determine their 

magnetic and crystalline properties. Films on MgO substrates 

exhibit excellent epitaxial properties and have high perpendicular 

magnetic anisotropy when measured using a vibrating sample 

magnetometer (VSM). Films on SrTiO3 were also epitaxial, but 

did not exhibit significant perpendicular anisotropy in VSM scans. 

Both films were patterned to create nanopillars, but for brevity only 

the pillars on MgO will be discussed here.

Results and Discussion: As shown in the figure, a negative resist, 

hydrogen silsesquioxane (HSQ), was used for electron beam lithography, 

with different island size and density. A patterned/developed HSQ 

resist island array was then pattern transferred to silicon surface to 

obtain a periodic Si pillars, obtaining a bit density as high as 1.6 Tb/in2.

In the patterned magnetic media, the magnetic islands need to be 

separated with minimal magnetic material in between spaces to 

minimize magnetic signal interference. In addition, the topographical 

configuration should be planar on the surface so as to allow the read/

write head slider to fly. As a demonstration, we fabricated a ≈100 nmdiameter diameter periodic array of Si nano pillars using electron beam 

lithography and nano imprint lithography (NIL). Each of the samples 

contained approximately 100 million Si nanopillars over a relatively large 

area of 0.6 cm x 0.6 cm. The vertically anisotropic magnetic material, 

[Ta 3 nm\Pd 3 nm\[Co 0.3 nm\Pd 0.8 nm]8] was sputter deposited on top 

of the Si islands as well as in the valleys (trenches). A geometrical 

planarization process was then applied, using HSQ spin coating, back 

etch, and conversion of the trench HSQ into SiO2

 by annealing. Because 

the HSQ gets preferentially etched over the magnetic material, the 

end result is a planar surface with islands of high coercivity magnetic 

recording material exposed only on top of the pillars. Much cleaner 

magnetic force microscopy images were obtained, with no obvious 

inter-bit magnetic interactions, and excellent read/write head flyability 

was demonstrated. Patterned media without such planarization did not 

allow the recording head to fly off the disk surface at all.

Recent Publications:

Planarization of discrete track recording media to improve flyability of 

magnetic recording sliders, Y. Yoon, C. Choi, Y. Oh, D. Hong, S. Jin, and 

F. E. Talke, IEEE Transactions on Magnetics 45, 3527-3530 (2009).

Highly self-assembled nanotubular aluminum oxide by hard anodization, 

K. Noh, K. S. Brammer, H. Kim, S.-Y. Jung, T.-Y. Seong, and S. Jin, 

Journal of Materials Research 26, 186-193 (2011).

Magnetic Nanopillars Fabricated Using 

Electron Beam Lithography

Research Participants: R. B. Comes,1 M. Gu,1 M. Khokhlov,1,2 R. 

Kasica,3 G. Henein,3 J. Lu,1 and S. A. Wolf1

1

Department of Materials Science and Engineering, University of 

Virginia, Charlottesville, VA 22904

2

Guilford College, Greensboro, NC 27410

3

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

Project Goal: CoFe2O4 nanopillars will be fabricated with perpendicular 

magnetic anisotropy to produce magnetic quantum cellular automata.

Key Accomplishments:

•	 Fabricated smallest reported CoFe2

O4 nanopillars using electron 

beam lithography.

•	 Demonstrated magnetic force microscopy imaging of nanopillars 

and dipole interactions between pillars.
•	 Imaged the complete magnetic nanostructure, including all 

three components of the magnetization vector, as a function 

of depth in patterned and unpatterned CoPd multilayers 

grown with graded magnetic anisotropy.

Background: Imaging magnetic structure at the nanoscale 

is a challenging and essential part of developing new magnetic 

materials and devices. Modern nanofabrication techniques 

are pushing magnetic structures towards smaller feature sizes 

and higher densities which test the spatial resolution of current 

magnetic imaging techniques. Magnetic recording media are 

a prime example. Demand for higher storage densities has 

resulted in multilayer nanostructures for perpendicular anisotropy, 

nanolithography for patterned media, and graded or exchange 

coupled multilayer films for combining thermal stability with write 

ability.

SEMPA images of (a) a patterned Co/Pd multilayer film showing the 

topography, perpendicular magnetization (gray scale), and in-plane 

magnetization direction (color); and (b) the depth dependent magnetic 

structure of a graded Co/Pd multilayer film near the top (low anisotropy), 

middle (medium anisotropy), and bottom (high anisotropy) of the film.

Our goal is to develop tools and procedures to image the magnetic 

structure within these materials and devices, both with high spatial 

resolution and, where possible, with nanometer depth resolution. 

We previously showed that conventional argon ion sputtering can 

be used to depth profile magnetization in 6 nm thick layers of Co/

Cu mulitlayers. However, the layers in perpendicular media such 

as Co/Pd are ten times thinner and much more susceptible to ion 

damage. We have therefore developed low-energy ion milling 

techniques that reduce the extent of the ion damage and enable 

magnetic depth profiling of these materials.

Approach: Patterned and continuous film test samples based on 

[Co (0.4 nm)/Pd (0.6 nm)]60 multilayer films were grown at room 

temperature using dc magnetron sputtering. During deposition, the 

Ar gas pressure can be varied to change the interfacial roughness 

and grain size, producing a thickness dependent anisotropy in 

the film. Optical lithography and ion milling through an alumina 

mask are used to pattern some of the films, and all of the films are 

surface treated with a 6 nm thick Pd film.

2010 | 5 1

Using the Vistec, we were able to pattern pillars in the HSQ resist 

as small as 20 nm in diameter, with dot-to-dot pitch of 60 nm. After 

etching the resulting pillars have heights of approximately 35 nm 

above the substrate surface. However, the Ar milling process leads 

to an increase in the pillar diameter due to re-deposition of the etched 

material onto the sidewalls of the pillars. The resulting pillars have 

diameters of approximately 75 nm at the end of the process. For 

this reason, MFM characterization focused on pillars with a pitch of 

200 nm for the initial testing. While larger than the EBL patterned 

pillars, these pillars still represent the smallest features produced 

yet on a CFO film. We found that the pillars maintain their magnetic 

moments after processing and exhibit dipole interactions even on the 

relatively large length scale of 200 nm spacing.

Future work will focus on ways to enhance the magnetic properties of 

the films to demonstrate dipole coupling for MQCA logic, while also 

reducing the dimensions of the system by improving the Ar milling 

process. We will also conduct experiments to produce self-assembled 

CFO pillars by templating a SrTiO3 substrate using the Vistec EBL and 

depositing additional material after patterning.

Acknowledgments: R. B. Comes gratefully acknowledges support 

through the National Defense Science and Engineering Graduate 

Fellowship Program. This research was supported by Nanoelectronics 

Research Initiative, the National Science Foundation, and the Defense 

Advanced Research Projects Agency.

Recent Publications:

The promise of nanomagnetics and spintronics for future logic and 

universal memory, S. A. Wolf, J. Lu, M. R. Stan, E. Chen, and D. M. 

Trager, Proceedings of the IEEE 98, 2155-2168 (2010).

Imaging 3D Magnetic Nanostructure in 

Ferromagnetic Multilayers 

Research Participants: B. McMorran,1 D. T. Pierce, 1 J. E. Davies,2,3

P. Morrow,3 C. L. Dennis,3 J. W. Lau,3 R. K. Dumas,4 P. Greene,4 K. Liu,4

and J. Unguris1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Advanced Technology Group, NVE Corp., Eden Prairie, MN 55344

3

Material Measurement Laboratory, National Institute of Standards 

and Technology, Gaithersburg, MD 20899

4

Physics Department, University of California, Davis, CA 95616

Project Goal: To develop sample preparation methods that allow 

for direct imaging of the detailed nanomagnetic structure in delicate 

magnetic materials and devices that are used for magnetic storage and 

magneto-electronics. 

Key Accomplishments:

•	 Developed plasma-based procedures for cleaning and depth 

profiling ultra-thin magnetic multilayers while minimizing 

interfacial mixing and roughening.
PROJECT HIGHLIGHTS

5 2 | CNST 

Measuring Light-Matter Interactions in 

Chip-Based Optical Cavities 

Research Participants: M. T. Rakher,1 M. Davanço,1,2 A. 

Badolato,3 R. Bose,4 F. Gesuel,4 C. W. Wong,4 C. S. Hellberg,1,5 O. 

Painter,6 and K. Srinivasan1

1

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

2

Maryland Nanocenter, University of Maryland, College Park, MD 

20742

3

Department of Physics and Astronomy, University of Rochester, 

Rochester, NY 14627

4

Department of Mechanical Engineering, Columbia University, 

New York, NY 10027

5

Center for Computational Materials Science, Naval Research 

Laboratory, Washington, DC 20375

6

Department of Applied Physics, California Institute of Technology, 

Pasadena, CA 91125

Project Goal: To develop special near-field probes and 

nanofabricated optical cavities for measuring light-matter 

interactions with exquisite sensitivity, down to the single photon, 

single emitter level, and to thereby enable potential applications in 

classical and quantum information processing.

Key Accomplishments:

•	 Designed and constructed a cryogenic fiber probe station for 

efficient nanophotonic device characterization.

•	 Measured optical properties of PbS colloidal quantum dots 

integrated with silicon nanophotonic resonators.

Background: Measuring interactions between light and matter 

has both fundamental and practical importance. For example, 

lasers have had a profound influence on science and industry over 

the past 50 years. More recently, devices exploiting light-matter 

interactions at the smallest scale, between a single photon and 

a single atom, have been a proving ground for ideas in quantum 

mechanics and a test bed for quantum-information-processing 

applications. Our goal is to develop measurement tools to probe 

these interactions in solid-state systems. We focus on nanoscale 

light-emitting materials such as epitaxially grown quantum dots 

and solution-processed colloidal nanocrystals. These are solidstate structures that exhibit many of the important properties of 

isolated atoms. We measure these nanostructures both as-grown 

and also when integrated into nanofabricated devices like optical 

cavities, where light can be confined to a small volume for many 

thousands of optical cycles. Placing quantum dots in optical 

cavities enhances their interaction with light, and gives rise to 

a variety of physical phenomena that can be used in information 

processing devices.

We use scanning electron microscopy with polarization analysis 

(SEMPA) to image the magnetic structures. SEMPA images the 

magnetization by measuring the spin polarization of secondary electrons 

generated in a scanning electron microscope. The secondary electron 

spin polarization is directly related to the magnitude and direction of 

the sample magnetization. Our SEMPA tool can measure all three 

components of the magnetization vector. The spatial resolution of our 

SEMPA is at best 10 nm, while the probing depth is approximately 1 nm, 

determined by the escape depth of the polarized secondary electrons. 

The small probing depth provides excellent thin film sensitivity, but also 

demands atomically clean surfaces for imaging. Samples were cleaned 

and milled using low-energy (50 eV) Ar ions produced by a microwave 

coupled plasma. The average milling rate was 2.5 nm/min. 

Results and Discussion: The ion milling procedures were first tested 

by comparing SEMPA images from samples milled using low energy 

ions to samples cleaned using conventional higher energy (> 1 keV) ion 

beam sputtering. The samples cleaned with high energy ions clearly 

showed degradation of the perpendicular anisotropy. The high energy 

ion milling disturbed the well-ordered multilayer structure which 

diminished the perpendicular anisotropy, and the deeper we milled, the 

worse the damage. Ion milling with low energy ions, on the other hand, 

produced no observable damage even when we milled through most 

of a uniform sample. An example of a SEMPA image from a patterned 

Co/Pd sample after removing the Pd capping layer with low-energy ion 

milling is shown in the figure.

Low-energy ion milling was then used to depth profile the magnetic 

structure of Co/Pd films grown with a thickness dependent graded 

anisotropy. The figure shows depth dependent SEMPA images of the 

magnetic structure of a graded Co/Pd multilayer film with low anisotropy 

near the top, medium anisotropy in the middle, and high anisotropy 

near the bottom of the film. The SEMPA images show the domain fine 

structure increasing as expected with increasing anisotropy. 

Recent Publications: 

Measuring the effects of low energy ion milling on the magnetization of 

Co/Pd Multilayers using scanning electron microscopy with polarization 

analysis, B. J. McMorran, A. C. Cochran, R. K. Dumas, K. Liu, P. Morrow, 

D. T. Pierce, and J. Unguris, Journal of Applied Physics 107, 09D305

(2010). 

Reversal of patterned Co/Pd Multilayers with graded magnetic 

anisotropy, J. E. Davies, P. Morrow, C. L. Dennis, J. W. Lau, B. McMorran, 

A. Cochran, J. Unguris, R. K. Dumas, P. Greene and Kai Liu, Journal of 

Applied Physics 109 (2011), in press.
fluorescence spectroscopy and resonant scattering measurements 

on a single InAs quantum dot. We are also investigating other 

device architectures, including single quantum dots embedded in 

dispersion-engineered semiconductor waveguides. 

In the PbS/Si system, we have interrogated a low density of PbS 

quantum dots that have been spun onto silicon photonic crystal 

cavities (see figure). We have confirmed that the quantum dot 

integration does not degrade the cavity’s loss, and have performed 

measurements of cavity-filtered photoluminescence, looking at 

effects such as quantum dot “blinking” (fluorescence intermittency) 

and saturation. Going forward, we hope to improve the sensitivity 

of measurements on this system, eventually achieving the 

capability to characterize a single PbS quantum dot. 

Recent Publications:

Spectroscopy of 1.55 μm PbS quantum dots on Si Photonic crystal 

cavities with a fiber taper waveguide, M. T. Rakher, R. Bose, C. 

W. Wong, and K. Srinivasan, Applied Physics Letters 96, 161108

(2010). 

Fiber-coupled semiconductor waveguides as an efficient optical 

interface to a single quantum dipole, M. Davanço and K. Srinivasan, 

Optics Letters 34, 2542-2544 (2009).

Linear and nonlinear optical spectroscopy of a strongly-coupled 

microdisk-quantum dot system, K. Srinivasan and O. Painter, 

Nature 450, 862-865 (2007).

Probing Plasmonic-Photonic Interactions 

in Periodic Nanowire Arrays

Research Participants: J. D. Caldwell,1 O. J. Glembocki,1 F. J. 

Bezares,1 R. W. Rendell,1 R. Kasica,2 N. D. Bassim,3 H. Qi,1 S. M. 

Prokes,1 M. A. Mastro,1 J. P. Long,4 M. Ukaegbu,5 and C. Hosten5

1

Electronic Science and Technology Division, Naval Research 

Laboratory, Washington, DC 20375

2

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

3

Materials Division, Naval Research Laboratory, Washington, DC 

20375

4

Chemistry Division, Naval Research Laboratory, Washington, DC 

20375

5

Chemistry Department, Howard University, Washington, DC 

20059

Project Goal: To investigate the influence of photonic and 

interparticle effects on plasmonically-enhanced optical processes 

in periodic nanowire arrays for improved optical sensors and 

enhanced optical emitters.

Key Accomplishments:

•	 Fabricated periodic arrays of metal-coated semiconductor 

nanowires that exhibit average surface enhanced Raman 

scattering (SERS) enhancements greater than 1 × 108

.

2010 | 5 3

Scanning electron microscope image of a silicon photonic crystal cavity 

containing PbS quantum dots, and a schematic of the fiber coupling 

approach.

Approach: We fabricate optical cavities in the semiconductors GaAs 

and Si using electron beam lithography and plasma etching. The 

cavities are integrated with quantum dots in two ways. For GaAs, a 

layer of InAs quantum dots has been embedded in the GaAs device 

layer during its epitaxial growth. For Si devices, solution-processed 

PbS colloidal quantum dots are spin-coated on the samples after device 

fabrication (see figure). The quantum dots emit in the 980 nm/1300 

nm (InAs/GaAs) and 1550 nm (PbS/Si) wavelength bands. To measure 

these structures, we have built a custom cryogenic fiber probe station, 

whose key component is an optical fiber taper waveguide, fabricated 

out of standard telecommunications optical fiber. The waveguide 

diameter starts at 125 μm, standard for an optical fiber, and gradually 

decreases to about 1 μm, before gradually increasing back to 125 μm. 

It is positioned so that its narrowest section is adjacent to the cavity 

(see figure). At this juncture, a fraction of the light sent through the 

waveguide tunnels into the cavity, where it interacts with the quantum 

dot(s). Some of the light then tunnels back into the waveguide, and 

we measure the properties of this exiting light to identify the quantum 

dot interaction. Working in a cryostat provides access to temperatures 

between 6 K and 300 K, a range over which the quantum dot behavior 

varies widely. The optical fiber interface allows for a variety of different 

systems to be interrogated by simply exchanging the excitation source 

and detector.

Results and Discussion: In the InAs/GaAs system, we have focused 

on single quantum dots, measuring their fluorescence spectra, timeresolved emission, and photon statistics. Cavities fabricated in the CNST 

NanoFab have exhibited very high quality factors (low optical loss), and 

will be used to follow up on previous results in which we demonstrated 

that a single quantum dot in a cavity can strongly modify its response 

and forms a coupled quantum-dot-photon quantum system, similar to 

two atoms forming a molecule. The net result is a device in which 

a single semiconductor quantum dot, a structure with a characteristic 

length scale of 10 nm, can be effectively connected to the macroscopic 

fiber optics that are ubiquitous in modern communications. Through 

a detailed characterization of the device’s electromagnetic properties, 

we have shown that this structure can perform highly efficient 
PROJECT HIGHLIGHTS

5 4 | CNST 

layer deposition. These efforts create arrays of core-shell, Au- or 

Ag-coated nanowires (see figure). These structures may be used 

as substrates for SERS detection of adsorbed molecular species 

or in the case of direct-band-gap semiconductor nanowires, as 

enhanced emitters. We probe the SERS intensity using both microand telescopic Raman spectroscopy, where the enhancement 

factors of the array structures may be probed as a function of 

nanowire diameter and height, inter-wire gap, array size, and the 

characteristics of the plasmonic metal coating (metal thickness, 

uniformity, conformality, and roughness). These measurements 

are carried out at a variety of wavelengths within the UV-Vis-NIR 

range. Telescopic Raman spectroscopy is also utilized to probe 

the efficiency of these arrays for use in stand-off detection of 

dangerous molecular compounds such as explosive or chemical 

warfare agents. The emission efficiency of luminescence nanowire 

arrays is measured with micro-photoluminescence spectroscopy. 

Results and Discussion: In the Si nanowire arrays, we have 

focused on probing their use in SERS detection schemes. Periodic 

arrays of nanowires that were fabricated at the CNST NanoFab 

and NRL Nanoscience Institute have exhibited extremely high, 

uniform SERS enhancements, with average enhancement factors 

approaching 109 (see figure). These structures have a peak 

response that is strongly dependent upon the nanowire diameter, 

with the peak diameter being dependent upon the metal used for 

the coverage and the incident laser wavelength. The enhancement 

factor is also weakly dependent upon the interparticle gap. 

Theory predicts that as the particles are spaced closer to one 

another, coupling between the stimulated plasmons will lead to 

significantly larger electric field intensities and therefore much 

larger enhancement factors. This effect has previously been 

observed in coupled clusters of plasmonic particles; however, in the 

case of the periodic arrays, the largest enhancement factors were 

observed for the most widely spaced arrays. Our array structures 

have also been used to detect SERS from various compounds at 

distances of 10 m.

Recent Publications: 

Plasmo-photonic nanowire arrays for large-area surface-enhanced 

Raman scattering sensors, J. D. Caldwell, O. J. Glembocki, R. W. 

Rendell, S. M. Prokes, J. P. Long, F. J. Bezares, Proceedings of SPIE

7757, 775723 (2010).

Probing plasmonic confinement: the role of propagating and 

localized surface plasmons for SERS enhancement in periodic 

nanostructures, F. J. Bezares, J. D. Caldwell, O. J. Glembocki, R. 

W. Rendell, M. Feygelson, M. Ukaegbu, R. Kasica, L. Shirey, N. D. 

Bassim, and C. Hosten, Nano Letters, submitted.

•	 Observed plasmonic interactions between Au/Ag nanowire 

“caps” and underlying films that lead to over an order of 

magnitude increase in SERS output.

Background: Plasmons are coherent, resonant oscillations of 

electrons within metals, typically confined at surfaces and/or interfaces 

with dielectric materials. These oscillations induce large, localized 

electric fields that enhance optical processes such as the absorption, 

Raman scattering (SERS), fluorescence (SEFS), and/or luminescence. 

In nanostructures made of plasmonic metals, typically gold and silver, 

plasmons can be optically stimulated at the surface plasmon resonance 

(SPR) frequency, which is defined by the nanoparticle geometry. 

Research in the field of plasmonics has led to the development of 

plasmonic waveguides, superlenses, enhanced solar cells and optical 

antennas, and dramatic advancements in molecular spectroscopy, 

and has led to new fields of study, such as metamaterials. However, 

until very recently the vast majority of efforts in the field of SERS 

has focused either on isolated single or coupled plasmonic particles. 

This focus led to a great deal of basic physics being explored and 

the observation of single molecule detection within tightly spaced 

(< 10 nm) nanoparticles due to plasmonic coupling. However, the 

enhancements that were observed are highly localized within that small 

gap between the particles and therefore not ideal for attaining the large 

average enhancement factors that are necessary to realize enhanced 

optical sensors and emitters desired in most commercial and military 

applications. Our goal is to design and fabricate large-area, periodic 

arrays of plasmonic nanowires with varying particle dimensions, interparticle separations, and array sizes. We are focusing on Au- and Agcoated semiconductor nanowire arrays, probing the role that the array 

periodicity and nanowire architecture have upon the properties of the 

plasmonic fields and optical enhancements observed.

SEM image of 100 × 100 array of Au-coated Si nanowires. INSET: TEM image 

of individual nanowire. The bulk Raman spectrum of Neat (blue) and SERS 

spectrum of benzene thiol on Au nanowires (red), shows the 7 orders of 

magnitude increase in the number molecules detected

Approach: We fabricate periodic and aperiodic arrays of semiconductor 

nanowires such as Si, GaN, ZnO, and SnO2 using electron beam 

lithography, reactive ion etching, and vapor-liquid-solid growth. These 

nanowires are overcoated with Au or Ag using a variety of deposition 

techniques, including electron beam evaporation, sputtering, and atomic 
the first experimental measurements on radial p-n junction arrays. 

To simulate the effects of impurities in metallurgical grade Si, we 

intentionally contaminate our devices with Cu impurities. Radial 

junctions contaminated with Cu impurities show roughly a two-fold 

increase in efficiency compared to similarly contaminated planar 

p-n junction solar cells; however, the enhancement is a strong 

function of the radial junction pitch, with maximum enhancement 

occurring at a pitch that is twice the carrier diffusion length.

Approach: Radial junction arrays were fabricated by a combination 

of lithography and deep reactive ion etching to form 10 μm deep 

vias in boron doped Si wafers. This was followed by forming p-n

junctions using a spin-on glass phosphorus source. The vias had 

diameters of 2 μm and 0.13 μm, and a pitch of 10 μm, 4 μm, and 

0.5 μm (see figure). To simulate the effects of Cu impurities in 

metallurgical grade Si, we deposited Cu films on the backside of 

our devices and then thermally annealed them. Cu contamination 

decreased the electron diffusion length from approximately 500 

μm for clean Si to approximately 0.3 μm for contaminated Si, as 

measured using an electron beam induced current technique. The 

solar-to-electrical power conversion efficiency was measured in 

a system calibrated to deliver 100 mW/cm2 photon flux (1 sun) 

through an atmospheric mass 1.5 filter.

Results and Discussion: The shorter minority carrier diffusion 

length in Cu-contaminated Si lowered the efficiency of planar 

junction devices by an order of magnitude, approximately from 

8 % to 0.7 %. As expected, the efficiency of similarly contaminated 

radial p-n junction arrays with 10 μm pitch improved to 

1.1 %. Reducing pitch to 4 μm increased efficiency to 1.8 %, an 

improvement of approximately 40 %. This improvement can be 

attributed to carriers having a shorter distance to diffuse before 

being collected. Surprisingly, the device with the shortest distance 

between adjacent p-n junctions showed a dramatically decreased 

efficiency, performing even worse than the planar device. To explain 

this decrease, we developed a two dimensional model with heavily 

n-doped Si ‘fingers’ inserted into a lightly p-doped Si matrix, and 

calculated the internal quantum efficiency by numerically solving 

the drift-diffusion and Poisson equations. Varying the distance 

between adjacent junctions from a few to thousands of nanometers 

reproduced the experimentally observed trend. At a large pitch, 

decreasing the junction to junction distance dramatically improves 

efficiency by increasing the fraction of collected carriers, or 

decreasing the fraction lost to non-radiative recombination at 

Cu centers. This trend begins to saturate when the distance 

between the junctions approaches the carrier diffusion length, 

because further decreases do not improve collection efficiency. 

The performance drops sharply when the distance between the 

junctions falls below twice the depletion width. At that point, 

the p-n junction is not fully formed. This deficiency increases the 

minority carrier concentration and therefore the recombination 

rate for the light-generated electron-hole pairs.

2010 | 5 5

Efficiency Enhancement of Copper 

Contaminated Radial p-n Junction 

Solar Cells

Research Participants: A. Boukai,1 P. Haney,2 A. Katzenmeyer,3 G. 

M. Gallatin,2 A. A. Talin,2 and P. Yang4

1

Department of Material Science and Engineering, University of 

Michigan, Ann Arbor, MI 48109

2

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

3

Sandia National Laboratories, Livermore, CA 94551

4

Department of Chemistry, University of California, Berkeley, CA 94704

Project Goal: To demonstrate and characterize radial p-n junction 

photovoltaic devices with simulated lower cost and less pure 

metallurgical grade Si, and to develop a quantitative, physics-based 

model to explain the experimental observations.

Key Accomplishments:

•	 Fabricated and characterized the performance of a Si-based array 

of radial p-n junctions with high Cu contamination.

•	 Demonstrated its superior photovoltaic performance compared to 

a planar Si p-n junction device.

•	 Developed a two dimensional model of a p-n junction array to 

explain the dependence of performance on junction areal density.

•	

(a) SEM cross section of a radial junction Si solar cell; (b) Calculated internal 

quantum efficiency (IQE) and measured short circuit current density (Jsc) versus 

pitch of the nanowire array. Both show a similar trend of a maximum at twice 

the depletion width. Note the model is 2D while the sample is 3D, and the 

model parameters are such that it has a smaller depletion width than the 

experimental system.

Background: The need to employ high purity semiconductor grade 

Si in the fabrication of Si solar cells significantly increases their 

production costs. Given silicon’s long optical absorption length, high 

purity Si is used to provide the diffusion length needed for efficient 

carrier extraction. Unfortunately, using cheaper, metallurgical grade 

Si substantially degrades cell performance due to its shorter carrier 

diffusion length. Radial p-n junction solar cells based on vertical arrays 

of Si nanowires orthogonalize, to a first approximation, the direction 

of the light absorption and the minority carrier diffusion necessary to 

reach the junction. This approach has the potential to circumvent the 

requirement for high purity silicon in photovoltaic devices. We performed 
PROJECT HIGHLIGHTS

5 6 | CNST 

interpretation more straightforward. The nanoscale contacts were 

deposited by metal evaporation through silicon nitride stencil masks 

fabricated in the CNST NanoFab with arrays of small openings in 

the shape of dots as defined by electron beam lithography and an 

etch process. We compared the photoconductive AFM (PCAFM) 

measurements with different conductive tips to the properties of 

these nanodevices. We investigated BHJs based on the blends 

of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid 

methylester (PCBM) that have produced the most efficient devices.

Schematic of the photoconductive AFM measurement configuration, and 

the measured photo response of a 300 nm nanodot array under short 

circuit illumination conditions. The photocurrent color-coded map is 

superimposed directly on top of the 3D topography.

Results and Discussion: The nanocontact data and 

photoconductive AFM maps both consistently reveal that high 

efficiency electron collection is limited to sparse hot spots. Among 

different dots, a significant variation (up to a factor of 10) in the 

photocurrent response is observed. The surface topography by 

itself is very rough with peak to valley variations of up to 40 % 

of the total film thickness. We found no correlation between 

the topography and the photocurrent data. This suggests that 

variations in the material organization that affect topography have 

only minor effects on device performance. An analysis of nanodot 

photoresponse as a function of size showed that as the nanodot 

size increases, fluctuations in the short circuit current among 

different dots are reduced.

The diamond-coated tips used on the nanodots also worked well 

for direct contact and photocurrent measurements on the bare OPV 

film. The variations in photocurrent can be as large as an order of 

magnitude over lateral dimensions as small as 100 nm. The largest 

photocurrent is observed in “hot spots” of current which vary from 

tens of nanometers up to 200 nm across. The PCAFM results from 

the top surface are consistent with an electron blocking skin (P3HT) 

and dilute hot spots corresponding to PCBM nanocrystals on the 

top surface.

In an attempt to access the bulk nanomorphology, we used ultra-low 

angle microtomy cut the OPV film, removing the surface layer and 

exposing wedges along the cut directions. High-resolution AFM 

imaging along each slice shows that the top morphology is enriched 

with a P3HT skin. The bulk morphology transitions abruptly into the 

Recent Publications:

Efficiency enhancement of copper contaminated radial p-n junction 

solar cells, A. Boukai, P. Haney, A. Katzenmeyer, G. M. Gallatin, A. A. 

Talin, and P. Yang, Chemical Physics Letters 501, 153-158 (2011).

Nanoscale Characterization of Organic

Photovoltaic Devices

Research Participants: B. H. Hamadani,1 S. Jung,1,2 N. GergelHackett,3

 P. M. Haney,1 L. J. Richter,4 and N. B. Zhitenev1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Maryland Nanocenter, University of Maryland, College Park, MD 

20742

3

Physical Measurement Laboratory, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

4

Physical Measurement Laboratory, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

Project Goal: To develop measurement techniques capable of 

mapping the functional properties of novel nano-structured photovoltaic 

(PV) materials at the relevant length scales.

Key Accomplishments:

•	 Used nanocontacts fabricated with a minimally invasive 

processing scheme to probe the photoelectric response in organic 

PV (OPV) materials at 200 nm to 1000 nm length scales.

•	 Explored the applicability of conducting AFM probes for 

characterizing photo-response down to a 30 nm length scale.

Background: The performance of bulk heterojunction (BHJ) organic 

solar cells has recently improved significantly and much effort is under 

way to further explain the photophysical phenomena and mechanisms 

responsible for charge generation and transport in these systems. In 

these materials, electron donors (usually polymers) and acceptors 

(fullerene derivatives or other small molecules) are intimately mixed 

throughout the material. Recent performance improvements have been 

associated with better active layer ordering in both the polymer and 

the fullerene regions, resulting in enhanced optical absorption and 

increased carrier mobility. These improvements have led to increased 

interest in the role of the nanomorphology of the active layer on exciton 

dissociation and on the transport of free charge carriers inside the 

material and across collecting contact interfaces.

Approach: When investigating the role of nanomorphology on charge 

transport in organic photovoltaic films, greater insight is obtained when 

structural characterizations are combined with optical or electrical 

measurements at the nanoscale. We use a photoconductive AFM 

(see figure) to probe arrays of nanoscale metal electrodes (Ag, Ca, 

Au) fabricated directly on top of the active layer without lithographic 

patterning on the sensitive organic film. These nanodots act as 

miniature versions of macroscopic devices and therefore make data 
Approach: We are utilizing a self-folding approach, developed 

in our laboratory at the Johns Hopkins University, which enables 

precisely patterned 2D lithographic templates to be curved or 

folded into the third dimension. The structures curve or fold due 

to intrinsic or extrinsic stress. Specifically, we have been building 

on initial published work achieved using electron beam lithography 

to nanoimprinted samples thereby enabling cost-effective mass 

fabrication of these structures.

Results and Discussion: To date, we have been able to selfassemble 100 nm scale polyhedral particles with precise patterns 

in all three dimensions. We have also been able to create curved 

nanostructures with radii as small as 20 nm. These structures 

have been fabricated with precise patterns with a resolution of 15

nm, in all three dimensions, which is unprecedented. However, in 

our prior work we utilized electron beam lithography which limited 

us to the creation of small numbers of particles. In order to enable 

such an approach to be widely used, there is a need to enable mass 

production. Using the Nanonex imprinter in the NanoFab, we have 

been trying to enable such production of these nanostructures. 

We have been able to create molds of 2D templates and selfassemble 3D structures. One challenge that we seek to overcome 

is the ability to enable multilayer registration using nanoimprint 

lithography, which is challenging at the present time. However, we 

have succeeded in creating nanoimprinted lines and discs and are 

exploring the self-assembly of these structures. The advantage of 

nanoimprint lithography is really in throughput; i.e. we have shown 

that nanostructures can rapidly be fabricated over areas as large 

as 1 cm. Such parallel fabrication is not possible (cost-prohibitive) 

using electron beam lithography.

Recent Publications:

Self-assembly of lithographically patterned nanoparticles, J. H. 

Cho and D. H. Gracias, Nano Letters 9, 4049-4052 (2009).

Curving nanostructures using extrinsic stress, J.H. Cho, T. James, 

and D. H. Gracias, Advanced Materials 22, 2320-2324 (2010).

Three dimensional nanofabrication using surface forces, J.H. Cho, 

A. Azam, and D. H. Gracias, Langmuir 26, 16534-16539 (2010).

Plastic deformation drives wrinkling, saddling, and wedging of 

annular bilayer nanostructures, J.-H. Cho, D. Datta, S.-Y. Park, V. 

B. Shenoy, and D. H. Gracias, Nano Letters 10, 5098-5102 (2010).

2010 | 5 7

top film morphology, suggesting a very thin skin layer. Using several line 

scans across this transition region, we estimated a top layer thickness 

of 10 nm or less, confirming that the gross inhomogeneities occur at 

the surface rather than in the bulk organization. These results are 

consistent with published spectroscopic data revealing an abundance 

of polymer species at the air/OPV interface, as well as tomography data 

showing fine blending within the bulk.

Recent Publications:

Origin of nanoscale variations in photoresponse of an organic solar cell, 

B. H. Hamadani, S. Jung, P. M. Haney, L. J. Richter, and N. B. Zhitenev, 

Nano Letters 10, 1611-1617 (2010).

Self-Assembly of Lithographically 

Patterned Cubic Nanostructures

Research Participants: S.-Y. Park and D. H. Gracias

Department of Chemical and Biomolecular Engineering, The Johns 

Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218

Project Goal: To develop strategies for mass fabrication of precisely 

patterned 3D nanostructures.

Key Accomplishments:

•	 Demonstrated the use of nano-imprint lithography and selfassembly to synthesize 3D nanostructures.

•	 Applied nanoimprint lithography to create nanoporous 

membranes.

Background: Present day nanofabrication methods such as electron 

beam and nanoimprint lithography enable exquisite patterning, but are 

limited to planar fabrication. We have been exploring the use of electron 

beam and nano-imprint lithography to precisely pattern 2D structures 

enabling them to be structured in 3D. Patterning of heterogeneous 

materials is very important to the creation of electronic, optical, and 

biomedical devices. In the absence of patterning, device functionality is 

severely limited. The state of the art in the creation of nanoparticles is 

limited to simplistic shapes like spheres and cylinders with only limited 

patterning. To overcome this challenge, we are utilizing a combination 

of lithography and self-assembly to enable precisely patterned 3D 

nanoparticles and nanostructures composed of metals, dielectrics 

(including polymers), and semiconductors to be created. Because of the 

high surface area to volume ratio in 3D particles, we anticipate novel 

properties for solar, plasmonic, and drug delivery devices.

(a) Present day nanoparticles have limited patterns (b) Our proposed nanoparticles and (c-e) fabricated nanoparticles, including precisely patterned 

polyhedral nanostructures.
PROJECT HIGHLIGHTS

5 8 | CNST 

a large area of material with relatively low fluence to minimize the 

radiation damage. X-rays also penetrate the material, sampling 

the structure through its entire thickness. 

Diblocks as used for these kinds of patterning are typically 

thin films, roughly a domain-spacing thick. With low atomic 

number elements and film thicknesses less than 50 nm, the two 

components in diblocks typically have low X-ray absorption crosssections. However, the level of X-ray scattering from the film and 

the contrast between the two phases can be dramatically improved 

using resonant scattering. This method involves using low-energy 

X-rays and tuning their energy precisely (within 0.1 eV) to match 

a particular resonance in the molecular structure of one of the 

diblock components; for example a C=O bond. In addition, in order 

to eliminate background scattering from the substrate, the diblock 

films are created on SiN membranes only 100 nm thick fabricated 

in the CNST NanoFab.

Results and Discussion: Alignment of the diblock to an 

underlying lithographic pattern results in the formation of a 

diffraction pattern whose major features are determined by 

the periodicity of the lithographic pattern, but whose details 

are controlled by the diblock’s morphology. The net outcome is 

extremely high-quality X-ray diffraction data, with good contrast 

and low noise out to large scattering angles. This data quality 

has enabled sophisticated fitting algorithms to be used with 

confidence to extract parameters including LER and the interfacial 

width between the two phases. Because the X-rays sample the 

full film thickness, the technique can also determine the sidewall 

angle between the two phases— something that was previously 

only modeled. 

Future directions in this area will include the use of this technique 

to measure the extent of the deprotected, latent image in 

chemically amplified resists, a measurement of significant interest 

to the semiconductor industry. In addition, we plan to explore 

the potential of guided self-assembly to produce large areas 

of orientated nanostructures for enhanced X-ray and neutron 

scattering experiments.

The electron microscopy image shows a randomly oriented, 50:50 

lamellar poly(styrene-b-methymethacrylate) diblock. (Note that the 

image appears to show that the relative proportions of the two phases 

are not 50:50.) The X-ray diffraction pattern obtained from an aligned

sample of the same material exhibits diffraction peaks out to 6th order 

and extremely low background scattering. 

Line-Edge Roughness Measurements in 

Diblock Copolymers

Research Participants: G. E. Stein,1,2 A. L. Aquila,3 E. M. Gullikson,4

and J. A. Liddle1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Department of Chemical and Biomolecular Engineering, University of 

Houston, TX 77204

3

Applied Science and Technology Graduate Group, University of 

California, Berkeley, CA 94720

4

Materials Sciences Division, Lawrence Berkeley National Laboratory, 

Berkeley, CA 94720

Project Goal: To develop a technique for measuring the intrinsic lineedge roughness in diblock copolymer systems targeted for integrated 

circuit manufacture. 

Key Accomplishments:

•	 Developed precise and robust sample fabrication methods to 

enable transmission X-ray scattering measurements of polymer 

thin films.

•	 Developed resonant soft X-ray scattering measurement and data 

analysis techniques to determine line-edge roughness in block 

copolymers and latent-image photoresist samples.

Background: Diblock copolymers are materials in which two 

immiscible polymer chains are covalently linked, leading to the 

formation of self-assembled phase-separated structures in which the 

domain size is controlled primarily by the size of the two component 

polymers. These materials have rich phase diagrams and can be 

used to generate nanoscale repeating structures with precisely 

defined domain sizes and spacings. In principle, because the system’s 

morphology is determined by its thermodynamics, guided self-assembly 

of diblocks on lithographically patterned surfaces may eliminate the 

statistical effects that plague conventional patterning methods. These 

materials may be important for fabricating integrated circuits and future 

generations of patterned magnetic media for data storage. In both 

cases, the variability in nanoscale features can lead to an unacceptable 

inconsistency in individual bit or transistor performance. In integrated 

circuit manufacturing, it is essential to determine which process steps 

significantly add to the line-edge roughness (LER) of the completed 

devices in order to develop strategies to mitigate them to satisfy 

current and future device requirements. Measuring the intrinsic LER 

in a diblock, and the LER after guided self-assembly, provides a way of 

screening candidate material systems in order to find those with the 

lowest LER. It also enables the material and process contributions to 

be separated.

Approach: Nanoscale polymer structures are notoriously difficult 

to measure using techniques such as scanning electron microscopy 

because the materials are frequently radiation sensitive, causing them 

to change and deform while being imaged. Other metrology methods, 

including atomic force microscopy, only probe the upper layer of the 

material. To avoid these problems, we instead used X-ray scattering over 
whose concentration is proportional to the image intensity. The 

photoresist then undergoes a post exposure bake process during 

which the acid diffuses and “deprotects” the resist by converting 

insoluble molecules to soluble ones. The photoresist is developed 

by washing away the soluble regions, leaving the insoluble regions 

as the pattern. Base quencher, which neutralizes acid, is often 

added to the photoresist to limit acid diffusion, which degrades the 

resist resolution, and to control exposure dose levels.

The lower cluster of curves in the top figure shows the power spectrum 

density (PSD) of the wafer LER without exposure statistics (i.e., no acid 

shot noise). The frequency contribution from the mask LER is clearly 

visible as the bump in the PSD at frequencies of about 20 lines/μm. But, 

the bump disappears as the acid diffusion range, R, increases. The upper 

gray curve is the standard shape produced by acid shot noise alone. The 

lower figure shows computed wafer PSDs including both mask effects 

and acid shot noise for R = 10 nm, for various exposure doses. These 

curves are essentially indistinguishable from those created by acid shot 

noise alone.

Approach: Our model predicts the variation in the statistics of 

the wafer LER as the relative contributions from the mask LER and 

the statistics from the exposure and processing of the photoresist 

are varied. Following the tenets of quantum mechanics, the image 

intensity acts mathematically as a probability distribution for the 

positions where photons will be absorbed and an acid molecule 

will be released. These exposure statistics are often termed “acid 

shot noise” since the number of acid molecules generated in any 

small volume obeys Poisson statistics. Coupled partial differential 

equations describe the reaction and diffusion of the acid, along 

with the deprotection of the photoresist. These equations 

are solved by a combination of analytical manipulation and 

numerical evaluation. The final step, photoresist development, 

is highly nonlinear and difficult to model. However, most modern 

photoresists respond primarily in a binary fashion. Regions where 

2010 | 5 9

Acknowledgments: Soft X-ray scattering measurements were 

performed at the Advanced Light Source at Lawrence Berkeley National 

Laboratory. 

Recent Publications: 

Measuring the structure of epitaxially assembled block copolymer 

domains with soft X-ray diffraction, G. E. Stein, J. A. Liddle, A. L. Aquila, 

and E. M. Gullikson, Macromolecules 43, 433-441 (2010).

The Effect of Resist on the Transfer of 

Line-Edge Roughness Spatial Metrics from 

Mask to Wafer

Research Participants: G. M. Gallatin1 and P. P. Naulleau2

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

 2Center for X-ray Optics, Lawrence Berkeley Laboratory, Berkeley, CA 

94720 

Project Goal: To develop an algorithm and associated computer code 

for predicting the extent to which both surface and edge roughness on 

an extreme-ultraviolet (EUV) mask is transferred to line edge roughness 

(LER) in the exposed and developed photoresist patterns on a wafer. 

The computational tools will need to account for shot noise effects in 

the exposure process, as well as diffusion and acid-base neutralization 

in the photoresist.

Key Accomplishments: 

•	 Early aerial-image modeling results have demonstrated the 

importance of mask-induced LER, and have informed the 

development of methods for experimentally determining the 

presence of such effects. 

•	 Exposure statistics have been added to the model, and have 

shown that these proposed experimental methods are viable only 

in cases where the contribution to total wafer LER due to acid 

shot noise is negligible compared to that due to mask induced 

LER. 

•	 The model has predicted that in certain cases, even with the 

mask LER being the dominant contributor, the wafer LER remains 

indistinguishable from that produced by exposure statistics alone.

Background: Many next generation computer chips, with features 

on the scale of 22 nm and below, will be fabricated using extreme 

ultra-violet (EUV) lithography. The tolerances for feature size, shape, 

placement, etc., for these devices range from a maximum of a few 

nanometers down to less than 1 nm. One critical parameter, the LER, is 

required by the International Technology Roadmap for Semiconductors 

to be less than 2 nm. Unfortunately, LER values are still several 

nanometers, with the best case a little over 2 nm, for processes that 

meet all other requirements. To reduce this value to below 2 nm, its 

sources must be determined. Mask features themselves have an 

LER of about 10 nm which, in a 5x reduction EUV imaging system, is 

reduced to 2 nm on the wafer. Additionally, modern photoresists are 

“chemically amplified;” i.e., the absorption of a photon releases an acid 
PROJECT HIGHLIGHTS

6 0 | CNST 

Key Accomplishments:

•	 Combined critical dimension small angle X-ray scattering 

(CD-SAXS) shape measurements with a finite-element 

inversion analysis of the acoustic modes from Brillouin light 

scattering to identify finite-size effect reductions of the 

elastic constants of polymeric nanolines fabricated by NIL.

•	 Established a structure-property-processing understanding 

of how the rheology of polymer flow in the nanoscale 

cavities of a NIL mold lead to residual stresses and physical 

instabilities in NIL generated patterns.

•	 Used X-ray based pattern shape measurements to quantify 

the patterning fidelity of cubic silsequioxanes (SSQs) as NIL 

template replication materials; validated their subsequent 

performance as high performance, low-cost secondary 

imprint templates.

Background: Nanoimprint Lithography (NIL) was originally 

developed as a versatile, low-cost, and high-resolution patterning 

alternative for optical lithography in CMOS fabrication. 

However, it is becoming apparent that NIL has great potential 

for nanotechnology in general. It is capable of patterning sub-10 

nm features directly into a range of materials, even functional 

materials, and not just sacrificial resist formulations. Intense 

research and development activities are currently centered on not 

just CMOS logic devices, but also bit patterned data storage media, 

high brightness light-emitting diodes (LEDs), patterned biological 

devices, optical devices, and a range of emerging technologies.

Approach: Our approach is to develop measurement platforms 

to quantify the quality of the pattern or feature that has been 

fabricated by NIL. These quantitative assessments of the imprint 

process are necessary inputs to optimize the development of NIL 

and move from novel demonstrations or devices in the lab to the 

high volume nanomanufacturing required for commercialization. 

To accomplish this goal we leverage our expertise in accurately 

measuring physical shape and properties of nanoscale structures. 

For the shape measurements we utilize our critical dimension 

X-ray scattering (CD-SAXS) and X-ray reflectivity methods to nondestructively determine the 3D shape of both the mold cavities and 

the imprinted structures with nanometer-scale resolution. This 

approach provides us with a quantitative assessment of the fidelity 

of pattern transfer. Then we quantify the way that the NIL process 

itself influences properties of the imprinted material and determine 

if this influence has an impact on the performance, robustness, and 

the deprotection density is above a given value wash away and regions 

below that value do not. The LER can therefore be determined by simply 

thresholding the deprotection density. 

Results and Discussion: In the absence of acid shot noise, the 

contribution of mask LER is clearly detectable as a bump in the 

measured power spectral density (PSD) of the wafer LER. However, 

when acid shot noise is included, the bump can vanish, indicating that 

although mask-induced LER is still dominant, in this case it would be 

impossible to determine this from just the wafer LER PSD since it is 

virtually indistinguishable from the PSD produced by acid shot noise 

alone. Therefore, the PSD of the wafer LER cannot be used reliably to 

determine the contribution to the wafer LER coming from roughness on 

the mask.

Recent Publications:

The effect of resist on the transfer of line-edge roughness spatial 

metrics from mask to wafer, G. M. Gallatin and P. P. Naulieau, Journal of 

Vacuum Science & Technology B 28, 1259-1266 (2010).

Measurement Platforms to Facilitate 

Nanoimprint Lithography

Research Participants: H. Ro,1, H. J. Lee,1 L. Chen,2 K. Kearns,1 T. 

Germer,3 W.L. Johnson,1 Y. Ding,4 K. Alvine,5 and C.L. Soles1

1

Material Measurement Laboratory, National Institute of Standards 

and Technology, Gaithersburg, MD 20899

2

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

3

Physical Measurement Laboratory, National Institute of Standards and 

Technology, Gaithersburg, MD 20899

4

Department of Mechanical Engineering, University of Colorado at 

Boulder , Boulder, CO 80309

5

Pacific Northwest National Laboratory, Richland, WA 99352

Project Goal: To develop, advance, and demonstrate measurements 

that facilitate nanoimprint lithography (NIL) as a viable technology for 

the patterning of robust, reliable, and functional nanostructures with 

dimensions smaller than 25 nm. These measurements will be critical 

as NIL transitions from a novel laboratory patterning technique to a 

commercial one for producing nanostructures for applications as diverse 

as semiconductors, bit-patterned magnetic media, high brightness 

LEDs, biotechnology, and other emerging technology sectors.

(a) Primary SiOx imprint into TTSE. (b) Secondary Imprint using TTSE replica.
Project Goal: To explore applications of the CNST-developed 

magneto-optical trap ion source that make use of its unique 

brightness and range of ionic species to realize new measurement 

and fabrication methods, enabling new nanotechnology tools for 

future electronics, nanofabrication, and energy.

Key Accomplishments:

•	 Designed and constructed a laser-cooled, magneto-optical 

trap-based chromium ion source and demonstrated first-ever 

images with a focused Cr ion beam.

•	 Designed and constructed a laser-cooled, magneto-optical 

trap-based lithium ion source mounted on a commercial 

focused ion beam column, creating the first Li ion microscope.

MOTIS image of a damaged multichannel plate acquired using a 

2 kV, 10 pA beam of Li ions.

Background: Focused ion beams (FIBs) are a proven tool for 

nanoscale surface modification and interrogation, having been 

used for over two decades for material removal (milling), material 

deposition, microscopy, and ion implantation. Collectively, 

commercial tools that use focused ion beams make up a 

$300 million to $600 million industry, with customers ranging from 

circuit manufacturers doing fabrication-line diagnostics and circuit 

edits, to basic researchers making new discoveries in nanoscale 

material development. However, FIBs are generally limited 

because they lack source flexibility. The commonly used liquidmetal ion source (LMIS) uses ions from the metal gallium (Ga), 

which is useful for milling because of its relatively large mass. It 

has also seen wide application in material deposition by induced 

beam chemistry using precursor gases. Unfortunately, gallium can 

contaminate nanostructures by implanting, and is destructive in 

microscopy because it erodes the sample. Expanding the available 

ion species beyond gallium would create a suite of focused ion 

beam tools with a range of new nanofabrication and imaging 

possibilities, including high-resolution microscopy, new beam 

chemistry processes for material removal and deposition, and 

entirely new applications in nanoscale analysis and fabrication. 

Focused to the nanometer scale, light ions could image without 

damaging the sample, heavy ions could efficiently remove material 

by sputtering, and specific ionic species could be exploited for their 

chemical, material or conductive properties to perform localized 

chemistry, deposit high purity nanoscale conductors, or implant 

dopants.

2010 | 6 1

quality of the imprinted device. By providing the measurement portion 

of the processing–properties–structure paradigm, we facilitate the 

development of technologies based on NIL patterning.

Results and Discussion: A central theme in our research is the 

development and use of X-ray methods, including CD-SAXS and specular 

X-ray reflectivity, to quantify the physical shape or profile of nanoscale 

structures with sub-nm resolution. These methods are non-destructive 

and applicable to nanostructures in a wide range of materials, allowing 

us to quantify the pattern shape in both the mold and the imprint, and 

thereby establish the fidelity of the pattern transfer process without 

sacrificing the molds or patterns. This approach is a powerful tool for 

improving and evaluating NIL processes.

Recently, we used these non-destructive and quantitative pattern shape 

measurement to address several materials issues related to NIL. One 

notable example, briefly summarized here, uses the quantitative fidelity 

of pattern transfer concept to determine the feasibility of using solution 

processable sol-gel cubic SSQs as template replication materials for 

generating low-cost secondary imprint molds. A SiOx imprint master 

was fabricated by conventional 193 nm optical lithography and 

imprinted into the spin-on SSQ material (referred to as TTSE) film at 

low temperatures. The as-imprinted TTSE patterns were then heated 

to convert the TTSE precursors into a hard cross-linked organosilicate. 

This material showed excellent thermal stability, a high modulus, a 

low surface energy, and quartz-like transparency in the ultraviolet (UV) 

spectrum. The figure summarizes the different cross-sectional linespace patterns obtained by fitting the X-ray data. Part (a) reveals a small 

amount of shrinkage in the TTSE replica that occurs after imprinting, 

during the high temperature vitrification. However, the TTSE replica can 

be used to directly imprint polystyrene (PS) patterns, shown in part (b), 

with an extremely high fidelity of pattern transfer.

Recent Publications:

Elastic constants and dimensions of imprinted polymeric nanolines 

determined from Brillouin light scattering, W. L. Johnson, S. A. Kim, R. 

Geiss, C. M. Flannery, C. L. Soles, C. Wang, C. M. Stafford, W. Wu, J. M. 

Torres, B. D. Vogt, and P. R. Heyliger, Nanotechnology 21, 075703 (2010).

Stability and surface topography evolution in nanoimprinted polymer 

patterns under a thermal gradient, Y. Ding, H. J. Qi, K. J. Alvine, H. W. Ro, 

D. U. Ahn, S. Lin-Gibson, J. F. Douglas, and C. L. Soles, Macromolecules

43, 8191-8201 (2010).

Cubic silsesquioxanes as a green, high-performance mold material for 

nanoimprint lithography, H. W. Ro, V. Popova , L. Chen , A. M. Forster , Y. 

Ding , K. J. Alvine , D. J. Krug , R. M. Laine , and C. L. Soles, Advanced 

Materials 23, 414-420 (2010).

Novel Sources for Focused Ion Beams

Research Participants: A. V. Steele,1 B. Knuffman,1 J. Orloff,2 and J. 

J. McClelland1

1

Center for Nanoscale Science and Technology, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

FEI Co., Hillsboro, OR 97124
PROJECT HIGHLIGHTS

6 2 | CNST 

Magneto-optical-trap-based, high brightness ion source for use 

as a nanoscale probe, J. L. Hanssen, S. B. Hill, J. Orloff and J. J. 

McClelland, Nano Letters 8, 2844-2850 (2008).

In Situ Measurements of Thermodynamics and Reaction Kinetics During 

Nanomaterials Synthesis and Catalysis

Research Participants: B. S. Mazzucco,1,2 V. Sharma,3 P. 

Dhollbhai,3 P. A. Crozier,3 J. B. Adams,3 R. Diaz,3 S. W. Chee,4 J. 

Drucker,5 P. Rez,5 S. Mahajan,6 S. Hofmann,7 A. D. Gamalski,7 A. 

Herzing,8 J. Wagner,9 and R. Sharma1

1

Center for Nanoscale Science and Technology, National Institute 

of Science and Technology, Gaithersburg, MD 20899

2

Maryland Nanocenter, University of Maryland, College Park, MD 

20742 

3

School for Engineering of Matter, Transport and Energy, Arizona 

State University, Tempe, AZ 85287

4

LeRoy Eyring Center for Solid State Science, Arizona State 

University, Tempe, AZ 85287

5

Department of Physics, Arizona State University, Tempe, AZ 

85287

6

Ira A. Fulton School of Engineering, Arizona State University, 

Tempe, AZ 85287

7

Department of Engineering, University of Cambridge, Cambridge 

CB3 0FA, UK

8

Materials Measurement Laboratory, National Institute of Science 

and Technology, Gaithersburg, MD 20899

9

Center for Electron Nanoscopy, Technical University of Denmark, 

2800 Kgs. Lyngby, Denmark

Project Goal: To measure how growth and pressure affect the 

thermodynamics, reaction rate, structure, and morphology of 

nanostructured zero- and one-dimensional materials.

Key Accomplishment:

•	 Catalytic activity of Ni catalyst for carbon nanotubes 

formation was improved by doping with 10 % to 20 % mole 

fraction of Au.

Background: Nanomaterials range from catalyst nanoparticles, 

where the surface area and atomic structure of the exposed surfaces 

control their activity and reactivity, to magnetic nanoparticles, 

where the properties are a function of their composition, size, 

and assembly. Recent advances in nanotechnology require 

very stringent control on the synthesis of nanomaterials so that 

they can be directly incorporated in the fabrication process. 

There is a growing need for developing and characterizing 

active nanostructures where the system components may be 

functionalized to interact in a controlled manner with the ambient 

environment (pressure, fields, stress, heat, etc.). To achieve this 

goal, it is essential to develop atomic-scale measurements of the 

Approach: For an ion source to be useful for nanoscale probe 

formation, it is essential for it to have a very small emittance, a high 

brightness, and a narrow energy spread. The magneto-optical trap ion 

source, or MOTIS, developed in the CNST, achieves these characteristics 

in an approach very different from the LMIS. Neutral atoms from an 

atomic beam are first slowed and then trapped in a magneto-optical 

trap, where they are laser-cooled to temperatures as low as 100 μK. 

A laser then ionizes the atoms in the presence of an extraction field, 

which accelerates them into a beam. The extremely low temperature 

the ions have when they are created translates into a very small spread 

in transverse velocities. This results in a very small emittance, which 

combined with an achievable current of as much as 100 pA makes for a 

very high brightness. The energy spread, fundamentally limited only by 

the cold atom temperature, but practically limited by source geometry, 

is also very low compared with the LMIS.

Having first demonstrated this source in 2008, we are currently 

undertaking two closely related projects aimed at characterizing its 

performance and exploring applications. In one project, a chromium 

MOTIS has been built, complete with a simple focusing and deflection 

system and a channel electron multiplier to detect secondary electrons. 

In the second project, we have constructed a lithium MOTIS that 

is completely compatible with a FIB system supplied by FEI, Co., our 

partner under a cooperative research agreement. This FIB system 

provides a high-quality focusing column, including beam alignment, 

stigmation and scanning, as well as an easy-to-use specimen chamber 

for rapid sample interchange.

Results and Discussion: The focused chromium ion system has 

recently come on line, allowing us to generate images and to study 

probe size as a function of source operating parameters. We have 

created ion beams with energies ranging from 0.5 keV to 3 keV, and 

currents of a few tenths of a picoampere. We observed probe sizes as 

small as 205 ± 10 nm (one-standard deviation radius), a spot size that is 

probably limited by the precision of our rudimentary ion optical system. 

The Li ion system has also become operational in recent months, and 

has generated the first high-quality images with resolution in the 

sub-100 nm range using 2 keV Li ions. Detailed studies of the source 

behavior are currently underway.

With the introduction of the MOTIS as a viable source for nanoscale 

focused ion beams, we are now poised to begin a wide range of 

research paths. In the near future, we will explore higher acceleration 

energies (up to 30 keV), novel beam chemistries with Li ions, and direct 

deposition of metal with Cr ions. Beyond this, by exploiting the unique 

ability of the MOTIS to produce single ions “on demand” for doping 

materials, we see a large number of possibilities with new ionic species 

such as Cs, noble gases, or rare earths.

Recent Publications:

Focused chromium ion beam, A. V. Steele, B. Knuffman, J. J. McClelland, 

and J. Orloff, Journal of Vacuum Science and Technology B 28, C6F1 

(2010).
In situ evaluation of the role of Au in improving catalytic activity of 

Ni nanoparticles for the formation of 1-D carbon nanostructures, 

R. Sharma, S. W. Chee, P. Rez, R. Miranda, and A. Herzing, Nano 

Letters, submitted.

Particle-Tracking Measurements of 

Nanoparticle Dynamics in Fluids

Research Participants: P. Carmichael,1 K. Du,1,2 J. Juarez,3 M. 

D. McMahon,1 P. Mathai,1,2 M. Bevan,3 B. Shapiro,4 E. Waks,5 G. 

Gallatin,1 J. J. McClelland,1 A. J. Berglund,1 and J. A. Liddle1

1

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

 2Maryland Nanocenter, University of Maryland, College Park, MD 

20742

3

Department of Chemical and Biomolecular Engineering, Johns 

Hopkins University, Baltimore, MD 21218

4

Fischell Department of Bioengineeringand Department of 

Electrical and Computer Engineering, University of Maryland, 

College Park, MD 20742

Project Goal: To develop faster, more reliable, and more 

sensitive methods for measuring, understanding, and controlling 

the forces and interactions experienced by nanoparticles in a 

fluidic environment. 

Key Accomplishments: 

•	 Developed “Orthogonal Tracking Microscopy” method 

that uses an optical microscope to repeatably resolve 

nanoparticle positions with 20 nm resolution in three 

dimensions.

•	 Developed a suite of statistical analysis tools for fast, 

robust, and accurate single particle tracking measurements.

Background: A sizable library of nanoparticles has been 

developed over the last few decades, having novel thermal, optical, 

mechanical, and chemical properties relative to their macroscopic 

counterparts. Assemblies of these fluid-based components promise 

disruptive improvements in several technological areas, including 

optics, electronics, catalysis and medicine, provided they can be 

organized into structures with nanometer precision on an industrial 

scale. This goal is hindered by the lack of measurement methods 

with suitable resolution (both in space and time) for monitoring 

assembly processes. By tracking and analyzing the motion of 

individual nanoparticles moving in solution and interacting with 

other particles and surfaces, we can determine the forces and 

interactions that govern the motion, internal dynamics, and fluidic 

self-assembly of nanoparticles, including large biomolecules, into 

organized structures.

2010 | 6 3

interactions with the ambient during controlled synthesis. Evolution of 

the morphology and the associated chemical and physical properties 

takes place both during the nanomaterial synthesis process and in 

response to external stimuli from the ambient; therefore, measurement 

of these complex transformations requires the use of advanced in 

situ methodologies so that the associated dynamic processes can be 

identified, understood, and measured.

Approach: We use a modified TEM to elucidate the nucleation 

and growth mechanism as well as the reaction kinetics. Most of 

the experiments to date have been performed using environmental 

scanning TEM (ESTEM) at either the Technical Institute of Denmark 

(DTU) or Arizona State University. Thin Ni/Au films (1 nm to 2 nm) with 

varying mole fractions were deposited using physical vapor deposition 

under high vacuum conditions. Samples were heated under the reactive 

gas environment and the dynamic changes recorded using electron 

diffraction, high resolution electron microscopy images (including 

videos), and electron energy loss spectra. This approach allows us to 

characterize the materials during synthesis. Post-synthesis analysis 

was also performed using energy-dispersive X-ray analysis at NIST.

Results and Discussion: For carbon nanotube growth, we have 

focused on the effect of Au doping in Ni on the activity of catalyst 

particles for the formation of carbon tubular structures. We find that the 

number of catalytically active particles for carbon nanotubes increased 

by a considerable amount for Ni thin films containing small amounts of 

Au (less than 20 % mole fraction). With higher Au content, the activity 

began to decrease, and pure Au samples were observed to be inactive 

for nanotube formation.

Low magnification images of the samples with (a) 100 % Ni, and (b) 80 % 

mole fraction Ni and 20 % mole fraction Au recorded after the thin films were 

exposed to approximately 0.3 Pa of C2H2 at approximately 510 °C. (c) High 

magnification STEM-EDS elemental map of a single catalyst particle showing 

high concentration of Au (green) at the tip and Ni (red) in the center.

Acknowledgments: Financial support from NSF-CBET (#0625340) 

and use of facilities in the LeRoy Eyring Center for Solid State Science 

at Arizona State University are gratefully acknowledged.

Recent Publications:

A spray drying system for synthesis of rare-earth doped cerium oxide 

nanoparticles, V. Sharma, K. M. Eberhardt, R. Sharma, J. B. Adams, and 

P. A. Crozier, Chemical Physics Letters 495, 280-286 (2010).
PROJECT HIGHLIGHTS

6 4 | CNST 

updating a decades-old theory to account for important technical 

considerations in modern experiments. The new method has been 

applied to analyze the nanometer-scale motion of quantum dots in 

an electrofluidic control setting.

Future directions in this area will include using real-time feedback 

control to track a particle’s position and simultaneously perform 

high-resolution spectroscopy, increasing spatial and temporal 

resolution for in situ measurements. 

Recent Publications:

Statistics of camera-based single particle tracking, A. J. Berglund, 

Physical Review E 82, 011917 (2010).

Manipulating quantum dots to nanometer precision by control of 

flow, C. Ropp, R. Probst, Z. Cummins, R. Kumar, A. J. Berglund, S. 

R. Raghavan, E. Waks, and B. Shapiro, Nano Letters 10, 2525-2530 

(2010). 

3D particle trajectories observed by orthogonal tracking microscopy, 

M. D. McMahon, A. J. Berglund, P. T. Carmichael, J. J. McClelland, 

and J. A. Liddle, ACS Nano 3, 609-614 (2009).

Atomic-Scale Silicon Surface Control 

to Enable Atom-Based Dimensional 

Metrology

Research Participants: R. M. Silver,1 P. Namboodiri,1,2 K. Li,1,3

S. Chikkamaranahalli,1,2 and J. Fu1

1

Physical Measurement Laboratory, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

KT Consulting NV, Antioch, CA 94509

3

Department of Physics, University of Maryland, College Park, MD 

20740

Project Goal: Develop a process to fabricate atomic-scale 

structures that can be accessed externally using robust fiducial 

marks, and demonstrate atomic-scale control of the surface 

morphology with large step-free atomically-flat regions on silicon 

for dimensional metrology.

Key Accomplishments:

•	 Achieved atomic-scale control of step flow patterns on the 

wafer scale.

•	 Produced atomically flat and extremely wide terraces (larger 

than 10 μm).

•	 Patterned silicon at the atomic scale with robust fiducials.

Background: An essential element of this project is 

the fabrication of test artifacts and structures for the 

development of high resolution calibration artifacts and methods. 

Atomic-scale fabrication and manipulation typically requires well 

ordered surfaces with control of the step-terrace morphology at 

the atomic scale. Moreover, in this work these samples need to 

be dimensionally stable and allow transfer to other measurement 

Reconstructed trajectory of a 190 nm-diameter fluorescent particle 

undergoing Brownian motion near two micromirror faces. The 3D positions 

are determined with a precision of 20 nm, significantly below the optical 

diffraction limit, and at frame rates greater than 300 Hz.

Approach: We use single-particle tracking methods to observe 

nanoparticle dynamics using an optical microscope and a sensitive CCD 

camera. The resulting data are analyzed to determine a nanoparticle’s 

position in each camera frame and to link these positions together 

into a trajectory containing information about a particle’s size, 

shape, and local environment. These methods are used widely to 

monitor transport properties in cell-scale biological processes and to 

determine rheological properties of complex fluids. We are working 

to extend and improve these techniques through experimental design, 

device fabrication, and theoretical analysis with the goal of rendering 

nanoparticle tracking a quantitatively reliable measurement method for 

resolving the nanometer-scale dynamics in engineered nanoparticle 

systems.

Results and Discussion: We have successfully addressed several 

outstanding measurement problems, developing techniques for 

resolving three-dimensional particle trajectories, actuating and 

controlling particle motion based on real-time data processing, and 

analyzing data quantitatively with statistically optimal methods. 

The interaction of a single nanoparticle with a patterned substrate is 

inherently a three-dimensional problem, since motion both within and 

normal to the substrate plane affects the dynamics. In order to monitor 

the full three-dimensional trajectory of a nanoparticle near a surface, 

we developed the “Orthogonal Tracking Microscopy” method in which a 

particle is observed in the vicinity of a pyramidal micromirror etched in 

a silicon substrate. The micromirrors, fabricated in the CNST NanoFab, 

provide a direct and reflected image in the microscope, which can be 

reconstructed to provide position information in three dimensions. We 

fabricated devices and performed an extensive analysis of systematic 

and random errors, demonstrating device performance with repeatable 

sub-20 nm, three-dimensional particle localization capability.

We also developed a suite of methods for extracting information such 

as particle position, orientation, and diffusion coefficient from the 

tracking data. We developed an optimal diffusion coefficient estimator, 
Results and Discussion: We have been able to obtain nearly 

identical step-terrace patterns in all the individual cells of the 

patterned sample. The atoms flow in the direction of the current 

[bottom-up in figure (a)], causing the steps to move in the opposite 

direction. Steps are accumulated at the boundaries defined by the 

fiducial patterns. As seen in the figure, a 25 μm cell has only one 

atomic step. The terrace width is larger than 10 μm, which is by far 

the largest terrace width reported. The step flow pattern is largely 

associated with the orientation of the micro-scale features. The 

patterns confine the steps to smaller regions, which help to remove 

the random fluctuations (usually associated with very long steps) 

and facilitate the formation of regular step arrays.

As shown in the figure, this method produces atomically ordered 

surfaces that are ideal for atom based metrology applications. 

Diffusion on a Si(100) surface is anisotropic because of the 1 × 

2 and 2 × 1 surface reconstruction. When a sample is heated by 

passing a direct current through it, the electromigration of Si atoms 

occurs. The electromigration introduces a bias in the diffusion so 

that the steps are swept aside gradually, leaving behind very large 

atomically flat terraces. The bias in the diffusion also drives the 

surface to a single domain, either 1 × 2 or 2 × 1 depending on the 

direction of the current.

This method offers vast potential for ‘engineering surfaces at the 

atomic scale’ and for enabling their use as templates for various 

applications related to atomic-scale fabrication. It will be also 

possible to fabricate step-bunch heights by controlling the pitch 

(depth of the etched trenches). Step bunches of various heights 

(typically 5 nm to 20 nm) could be produced in a single sample and 

be used as height standards. These structures are robust and can 

be persevered in a moderately controlled environment.

Nanoscale Linewidth Standards for AFM 

Calibration

Research Participants: C. McGray,1 R. Kasica,2 G. Orji,1 R. 

Dixson,1 M. Cresswell,1 R. Allen,1 and J. Geist1

1

Physical Measurement Laboratory, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

2

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

Project Goal: To refine AFM tip width calibration techniques and 

improve the traceability of the meter for nanoscale measurements 

by developing linewidth standard materials with near-atomicallysmooth surfaces.

Key Accomplishments:

•	 Achieved sidewall roughness as low as 0.6 nm (two atoms).

•	 Fabricated full range of widths from 200 nm down to 5 nm 

for linearity assessment.

Background: Accurate dimensional metrology is of utmost 

importance to the continued development of improved 

2010 | 6 5

tools that can measure the artifacts with dimensions known on the 

nanometer scale. Control of atomic-scale morphology of the substrates 

in the presence of fiducial marks that can withstand high temperature 

processing has been a long standing challenge. The ability to produce 

repeatable, large terrace patterns over an entire wafer in the presence 

of fiducials, while maintaining the ability to control the terrace width, 

would represent an exciting new advance to meet the needs of 

atomically precise manufacturing. Creating a process that leads to the 

spontaneous arrangement of atomic terraces and surface structure is a 

key objective of this project.

Native surfaces are not atomically flat and contain a variety of atomic 

steps. Even with the lowest miscut angle available, surface dynamics 

preclude atomically flat terraces stretching over a micrometer. However, 

it is known that the surface morphology can be altered with thermal 

processing procedures giving mobility to the surface atoms. The atoms 

have different dynamics depending on local bonding forces and on the 

process temperatures. A key achievement this year is the use of fiducial 

structures etched in the surface, which after thermal processing serve 

as boundaries for the evolution of step flow by confining the dynamics 

into individual cells.

(a) AFM image (25 μm × 25 μm) of two neighboring 25 μm cells prepared on a 

Si(100) sample after annealing at 1030 °C for 48 hr. The surface has only one 

atomic step, and terraces more than 10 μm wide. (The step flow patterns are 

nearly identical in every cell defined by the fiducial marks.) (b) STM image 

(20 nm × 20 nm) showing atomically-ordered, reconstructed surface.

Approach: We have fabricated micrometer sized fiducial patterns 

of 25 μm and 50 μm square in two orientations on a Si(100) sample 

using standard lithographic procedures and dry (plasma) etching in the 

CNST NanoFab. The patterns are formed by creating trenches or walls 

(2 μm wide). The samples were resistively heated by passing current 

and flash heating at 1230 °C for a few seconds, and then annealed at 

1030 °C for 48 hours. When heated, the micrometer scale patterns 

induce different mass transport kinetics due to the thermodynamics and 

electromigration effects.

The morphology of the step-terrace patterns can be controlled by 

optimizing the size and orientation of the fiducial patterns on the 

surface. The patterns provide boundary conditions and change the 

dynamics of the atomic processes by pinning the steps during high 

temperature processing. Control is achieved by optimizing the size, 

shape, and orientation of the patterns to obtain uniformly sized and 

spaced atomic steps on the surface.
PROJECT HIGHLIGHTS

6 6 | CNST 

extending all the way down to 5 nm. Having a range of widths 

in the standard will help users of AFMs calibrate the linearity of 

their instruments in the size ranges required by the semiconductor 

devices of today and tomorrow.

Recent Publications:

Comparison of measurement techniques for linewidth metrology 

on advanced photomasks, S. Smith, A. Tsiamis, M. McCallum, A. 

Hourd, J. T. M. Stevenson, A. J. Walton, R. G. Dixson, R. A. Allen, 

J. E. Potzick, M. W. Cresswell, and N. G. Orji, IEEE Transactions On 

Semiconductor Manufacturing 22, 72-79 (2009).

RM 8111: Development of a prototype linewidth standard, M. 

Cresswell, W. F. Guthrie, R. G. Dixson, R. A. Allen, C. E. Murabito, 

and J. V. Martinez De Pinillos, Journal of Research of the National 

Institute of Standards and Technology 111, 187-203 (2006).

Developing Nanocalorimetry Techniques 

and Material Standards for Measuring 

Properties of Exothermic Reactions in 

Multilayer Films

Research Participants: P. Swaminathan,1,2 D. A. LaVan,2 and T. 

P. Weihs1

1

Materials Science and Engineering, Johns Hopkins University, 

Baltimore, MD 21218

2

Material Measurement Laboratory, National Institute of 

Standards and Technology, Gaithersburg, MD 20899

Project Goal: To develop nanocalorimetry techniques for studying 

exothermic reactions in metallic multilayer films and use these as 

standards for improved nanocalorimeter measurements.

Key Accomplishments:

•	 Designed a high temperature, fast optical calibration 

procedure for nanocalorimeters.

•	 Characterized rapid melting and solidification events in thin 

metal films and multilayers.

Background: Reactive multilayer materials consist of alternating 

nanoscale layers of metals and/or alloys that react exothermically, 

forming stable intermetallics. These exothermic reactions can be 

exploited to cleanly bond dissimilar metals in sputter targets, and 

for joining temperature sensitive assemblies such as attaching 

silicon solar cells to heat sinks. Typical reaction fronts in these 

systems have velocities of the order of a few meters per second 

with heating rates as high as 106 °C/s and maximum temperatures 

of 1500 °C (1.5 ms from room temperature to 1500 °C). A wide 

variety of multilayer systems are being studied; because of the 

extreme temperatures and rates involved in these reactions, 

measuring their thermophysical properties presents unique 

measurement challenges, which are solved using a nanocalorimeter 

chip fabricated in the CNST NanoFab.

technologies in the semiconductor electronics industry, as device 

dimensions scale from 32 nm down to 22 nm and beyond. NIST helps 

to ensure measurement accuracy by providing linewidth standard 

reference materials that allow traceability of the meter down to these 

very small scales. Currently, standard uncertainties in the dimensions 

of these materials are approximately 1 nm. As critical dimensions in 

the semiconductor industry become smaller, this uncertainty becomes a 

larger percentage of the measurement. A new generation of linewidth 

standards is in development to provide uncertainties even smaller than 

1 nm.

Approach: The largest component of the measurement uncertainty 

in the current generation of linewidth standards is caused by nonuniformity in the width of the line along its length. We are therefore 

targeting uniformity improvements as the most important requirement 

of the next generation of linewidth standards under development. 

Since even the highest-resolution electron beam lithography systems 

do not yield the required uniformity, we instead use electron beam 

lithography in the CNST NanoFab only as a first step in the production 

of the linewidth standards. The lithographically-defined pattern is then 

transferred into a single crystal of silicon through the use of an etchant 

that selectively removes material to expose certain crystallographic 

planes which become effectively polished.

(a) SEM image of a next-generation linewidth standard structure. The line in 

the center of the image is defined by the two adjacent crystallographicallyetched hexagonal pits. (b) 3D topography of a linewidth standard structure as 

measured by critical-dimension atomic force microscopy

Results and Discussion: To ensure that the crystallographic etchant 

polishes the linewidth standards without dissolving them away, the 

linewidth standard structures must be very well-aligned to the facets of 

the crystal that are unaffected by the etchant. We have developed an 

auto-alignment method for accomplishing this requirement even when 

the orientation of the facets is not precisely known. Using this autoalignment method, we have been able to produce linewidth standard 

structures having non-uniformity as low as 0.6 nm.

The new generation of linewidth standards is being fabricated with 

integrated navigation features that will help AFM measurement 

scientists to precisely position their measurements. These features 

are expected to further reduce the uncertainty of the measurement by 

providing greater repeatability. Moreover, the new reference materials, 

shown in the figure, can now be fabricated with a range of widths 
Acknowledgments: This project is supported in part by NIST 

Grant 70NANB9H9146.

Recent Publications:

Optical calibration for nanocalorimetry measurements, P. 

Swaminathan, B. G. Burke, A. E. Holness, B. Wilthan, L. Hanssen, 

T. P. Weihs, and D. A. LaVan, submitted.

Dynamics of solidification in Al thin films measured using a 

nanocalorimeter, P. Swaminathan, R. K. Kummamuru, D. A. LaVan, 

and T. P. Weihs, submitted.

Microfluidic Bumping Chip for

Purification of Tumor Cells from Blood

Research Participants: J. B. Haun,1 L. Chen,2 M. Cangemi,2 H. 

Lee,1 and R. Weissleder1

1

Center for Systems Biology, Massachusetts General Hospital, 

Boston, MA 02114

2

Center for Nanoscale Science and Technology, National Institute 

of Standards and Technology, Gaithersburg, MD 20899

Project Goal: To develop a microfluidic device for rapid and 

selective concentration and separation of epithelial cancer cells 

from whole blood based on differences in size (12 μm to 20 μm 

in diameter for tumor cells, < 12 μm in diameter for blood cells). 

This device will facilitate detection and molecular profiling of 

circulating tumor cells obtained from “blood biopsies.”

Key Accomplishments:

•	 Designed and fabricated a microfluidic device for 

concentration and separation of tumor cells from blood.

•	 Created micropost structures with extremely high aspect 

ratio (4x greater than previously demonstrated) with vertical 

sidewalls.

Background: The ability to detect and molecularly analyze scant 

and unique cell populations would have far reaching applications 

in medicine and the life sciences. It would allow rapid detection 

of rare cells in clinical specimen, enable molecular profiling, and 

open a new era of medical diagnostics where rational treatment 

decisions could be based on quantitative molecular phenotypes. 

Circulating tumor cells (CTCs) are rare cancer cells that have 

escaped from a primary tumor site and entered the blood stream. 

They have been identified in the peripheral blood of most patients 

with metastatic disease and in patients with localized cancers, but 

at exceedingly low levels (about 1 CTC/mL to 100 CTC/mL of blood, 

or 1 CTC per million leukocytes). To date, CTCs have been used 

as a metric for tumor expansion, to predict disease progression, 

and to monitor treatment response. An emerging application is 

to use these cells for molecular analysis, thus reducing the need 

for invasive biopsies. Unfortunately, the ability to molecularly 

detect and profile CTCs has been largely lacking to date since 

existing clinical analysis techniques are not sufficiently sensitive. 

2010 | 6 7

(a) Photograph showing a self propagation reaction in a free standing Ni-Al foil. 

The reaction is initiated in the lower left corner of the foil and propagates across 

the foil, with a velocity of a few meters per second. Maximum foil temperatures 

can reach 1500 °C. The final product is a NiAl intermetallic. (b) An array of 

nanocalorimeters fabricated in the NanoFab. Each calorimeter consists of a Pt 

strip on silicon nitride membrane suspended on Si, with electrical connections 

made to each strip for heating and measuring resistance.

Approach: Nanocalorimetry quantitatively measures thermal and 

thermophysical properties in materials at the nanoscale using a very 

sensitive sensor chip with a thermal addendum (the heat capacity of 

the instrument) comparable to the sample. A typical device consists 

of a 50 nm platinum strip that is thermally isolated on a silicon nitride 

membrane suspended on a silicon die. Electrical connections to the 

die allow for current to be applied to heat the platinum strip, and for 

voltage and current measurements. The fabrication steps involved 

are fully implemented at CNST based on a 100 mm wafer that yields 

approximately 70 nanocalorimeter chips. Individual chips are cleaved 

from the wafer and then calibrated in the NIST Material Measurement 

Laboratory. Calibration involves measuring the temperature coefficient 

of resistance of the platinum by local Joule heating of the strip while 

simultaneously measuring resistance and temperature. The sample of 

interest is then evaporated onto the calibrated Pt sensor in the NanoFab 

and its properties measured.

Results and Discussion: We have fully optimized the high 

temperature calibration procedure for the nanocalorimeters, looking 

at issues of stability and repeatability of temperature and resistance 

measurements. Optical calibration requires measuring the emissivity of 

the Pt film as a function of temperature; these measurements have been 

performed in collaboration with Dr. Hanssen and Dr. Wilthan in NIST’s 

Physical Measurement Laboratory.

As a test of the calibration procedure, we have studied the melting 

and solidification of a 50 nm-thick aluminum sample at heating and 

cooling rates of 104 °C/s. At the rapid cooling rates achieved with a 

nanocalorimeter we can directly observe the effect of recalescence 

(temperature rise in a material due to release of its heat of fusion) in 

aluminum. Conventional scanning calorimeters operating at slower 

rates and with larger thermal addenda cannot capture this phenomenon.

Currently, we are measuring the thermophysical changes in Ni-Al 

bilayer systems with self heating rates around 106 °C/s, and plan to 

combine the nanocalorimeter measurements with post reaction and in 

situ microstructural measurements.
PROJECT HIGHLIGHTS

6 8 | CNST 

In the fabricated bumping chips, the large aspect ratio obtained is 4

times greater than that of previous versions while still maintaining 

vertical sidewalls. This improvement should dramatically increase 

device flow through, thus enabling large blood samples to be 

processed in a reasonable time frame. Ongoing work in the lab has 

been focused on developing novel techniques to label tumor cells 

with magnetic nanoparticles and improving the μNMR device (see 

recent publications). The performance of the bumping chips will 

be tested in the near future, modified if necessary, and integrated 

with the μNMR.

Recent Publications:

Chip-NMR biosensor for detection molecular analysis of cells, H. 

Lee, E. Sun, D. Ham, and R. Weissleder, Nature Medicine 14, 869-

874 (2008).

Rapid detection and profiling of cancer cells in fine-needle 

aspirates, H. Lee, T. J. Yoon, J. L. Figueiredo, F. Swirski, and R. 

Weissleder, Proceedings of the National Academy of Sciences 

USA 106, 12459-12464 (2009).

Bioorthogonal chemistry amplifies nanoparticle binding and 

enhances the sensitivity of cell detection, J. B. Haun, N. K. 

Devaraj, S. A. Hilderbrand, H. Lee, and R. Weissleder, Nature 

Nanotechnology 5, 660-665 (2010).

Neural Probes with Waveguides and a 

Fiber-Coupled Light Emitting Diode 

Research Participants: J. N. Mateo and B.G. Jamieson

Scientific Biomedical Microsystems, Columbia, MD 21046

Project Goal: To develop an implantable neural probe system to 

optically stimulate targeted neurons and record multi-cell neuronal 

activity by integrating a fiber-coupled light emitting diode (LED) 

with silicon probes fabricated with SU8 waveguides.

Key Accomplishments:

•	 Designed, constructed, and tested a fiber-to-LED coupler 

that couples a single LED to four optical fibers.

•	 Designed and began fabricating an integrated, extracellular 

recording array with micromachined fiber alignment grooves, 

an SU8 waveguide, and stress-compensated penetrating 

silicon shanks.

Background: Using an implantable, integrated microsystem 

to modulate neuronal activity with optical stimulation and to 

simultaneously record single unit action potentials is a potentially 

groundbreaking approach to systems neurophysiology. SB 

Microsystems is working with neurophysiologists at the Howard 

Hughes Medical Institute (HHMI) to produce highly integrated 

electrodes that can be used in studies of learning, memory, and 

In prior research, our lab developed a miniaturized NMR (μNMR). This 

device has been used to detect cells that are specifically tagged with 

superparamagnetic nanoparticles, thus providing a quantitative readout of cell number and biomarker expression level. A device capable 

of rapidly concentrating and separating rare CTCs from blood that 

could interface directly with the μNMR would be extremely powerful, 

increasing the detection sensitivity and selectivity of molecular analysis.

Approach: We designed a microfluidic device that utilizes an array 

of 10 μm-diameter posts that are offset from one column to the next 

along the direction of flow. The microposts were placed such that larger 

epithelial tumor cells (12 μm to 25 μm in diameter) are displaced while 

smaller blood cells (< 10 μm in diameter) pass straight through the 

device based on a technique termed deterministic lateral displacement. 

Lateral displacement devices, also known as ‘bumping chips,’ have 

previously been used to separate the various components of blood from 

one another, but to date have not been applied to isolation of tumor 

cells. We designed two different stages, the first for concentration of 

tumor cells to the center of the device and the second for high-level 

purification into buffer. Both stages were designed with four different 

micropost arrangements to optimize ‘bumping’ characteristics for 

tumor cells. To fabricate the bumping chips, standard photolithography 

techniques were employed at the CNST NanoFab to generate patterns 

of photoresist corresponding to the micropost structures on silicon 

wafers. The patterned wafers were subsequently etched using deepreactive ion etching via the Bosch process. Residual photoresist was 

removed using plasma treatment.

(a) Schematic of the lateral displacement device (‘bumping chip’), including the 

two separate stages. (b) SEM images of etched micropost structures.

Results and Discussion: To concentrate and separate tumor cells 

from blood, we have focused on fabricating a microfluidic device 

with micropost structures that were etched directly in silicon wafers. 

After optimizing the deep-reactive ion etching process, a protocol was 

developed that resulted in microposts with high aspect ratio (10 μm 

diameter, about 80 μm height) and extremely smooth vertical sidewalls.
2010 | 6 9

brain plasticity. When excitable cells with a genetically-expressed 

protein called Channelrhodopsin (ChR2) are exposed to blue light (480 

nm), neuronal action potentials are triggered in these cells. Light 

is typically delivered using a laser or an LED coupled to an optical 

fiber, and the electrical signals are probed using an independent 

microelectrode. Some recent efforts at integrating the light delivery 

with the microelectrode have been reported; however, these approaches 

rely on highly labor-intensive “one-off” assembly procedures in which 

optical fibers are etched and then manually aligned and attached to 

silicon recording arrays. Others have demonstrated probes with 

integrated waveguides, but the light sources (i.e. laser or LED) are bulky, 

are separate from the probe, and connected by a fiber, all of which is 

problematic for behavioral experiments. Designing a neural probe with 

integrated optical stimulation allows implanting the probes without a 

tether, and enables the selective stimulation and monitoring of neuronal 

activity in freely behaving animals.

Approach: MEMS silicon neural probes with integrated waveguides 

are being fabricated in the CNST NanoFab with a bulk micromachined 

silicon-on-insulator process. A top dielectric stack of stress-balanced, 

oxide-nitride-oxide layers provides hermeticity from the tissue during 

implantation. Recording sites are patterned from platinum or iridium, 

which can subsequently be oxidized to reduce site impedance. 

U-shaped grooves are wet-etched where the optical fiber is to be fixed, 

and an SU8 waveguide is patterned. Probe boundaries are etched with 

DRIE, with a second patterned DRIE backside etch used to release the 

probes from the wafer. An LED coupled to four optical fibers is fixed on 

a small headstage (printed circuit board), with fiber ends aligned in the 

grooves to the SU8 waveguides.

Results and Discussion: A coupler that connects a high intensity 

LED (XRE Cree XLamp) to four optical fibers has been designed, 

constructed, and tested. The coupler is made of ceramic, stainless 

steel, and brass, and is fixed onto the LED using an ultraviolet 

light-curable adhesive. The optical power values measured 

using a Thorlabs PM100A power meter at the end of each fiber is 

practically equal (±12 %) across the four fibers.

Passive neural probes (i.e., probes without optical stimulation) 

fabricated using the bulk micromachined SOI process described 

above are currently being used in behavioral experiments by 

our collaborators at HHMI. The integration of optical elements 

onto these devices represents an opportunity for a system-level 

approach that will accelerate experimental progress in this area.

More generally, SB Microsystems works on the integration of 

advanced functionality (CMOS circuitry, optical sources and 

detectors, acoustic sources and other actuators) into MEMS and 

microfluidic systems. The development of highly integrated and 

functional biomedical microsystems is key focus of the research 

and development work at SB Microsystems, and has been enabling 

the development of highly miniaturized, low power, and capable 

systems for biomedical applications.

Acknowledgments: SB Microsystems acknowledges Drs. Tim 

Harris and Sebastien Royer at HHMI, Dr. Gyorgy Buzskai at Rutgers 

University, and the team at Neuronexus Technologies, Inc.

(a) Schematic view of integrated probe with SU8 waveguide, an etched fiber alignment groove, and an array of metal microelectrodes for monitoring 

neuronal activity. A high intensity blue LED is coupled into the waveguide with a 4:1 coupler, not shown in this view, but shown in (b) in operation. (c) and 

(d) Optical micrographs of fabricated passive neural microprobes currently in use at HHMI.
7 0 | CNST

Personnel Highlights

The CNST technical staff includes Project Leaders, Postdoctoral and 

Student Researchers, Visiting Fellows, and Process Engineers and 

Technicians. The CNST offers a dynamic, multidisciplinary environment 

for scientists at all career stages—from high school interns, through 

senior researchers seeking a highly productive sabbatical visit.

N E W P R O J E C T L E A D E R S A N D 

NANOFAB STAFF

The CNST has brought together talented, motivated Project Leaders 

from many disciplines who are open minded about other fields and eager 

to collaborate on important measurement problems in nanotechnology. 

NanoFab Process Engineers and Technicians generally have broad 

nanofabrication and measurement experience, and the desire and 

ability to train and provide outstanding support to NanoFab researchers. 

The following staff members have joined the CNST since the start of 

FY2009 (October 1, 2008), listed alphabetically with the month that they 

started in parentheses.

Jerry Bowser (January 2010) is a NanoFab Technician with over 13

years of experience in semiconductor manufacturing engineering in 

the private sector, including five years at Allied-Signal and eight at 

Covega, where he held both engineering and supervisory positions. 

He has significant experience with diffusion/oxidation and chemical 

vapor deposition processes and has worked extensively with indium 

phosphide and lithium niobate optical devices.

Rachel Cannara (April 2009) is a Project Leader in the Nanofabrication 

Research Group. She received a B.S. in Physics with Highest Honors 

from the University of California, Santa Cruz, where her scholarship 

was recognized with numerous awards. She then received a Ph.D. in 

Physics from the University of Wisconsin-Madison, where she received 

the Hirschfelder Award for academic achievement and studied the 

tribological properties of single crystal diamond. Rachel joined CNST 

after two years as a Postdoctoral Fellow at the IBM Zurich Research 

Laboratory. Her current research focuses on the measurement and 

control of the mechanisms that govern nanoscale frictional energy 

dissipation, and the use of these discoveries to enable the design and 

operation of future nanomechanical and nanomanufacturing systems.

Andrea Centrone (August 2010) is a Project Leader and Visiting Fellow 

in the Energy Research Group. He received a Laurea degree and a Ph. D. 

in Materials Engineering from the Polytechnic University of Milan, Italy, 

where he developed a Raman cell to study the interactions between 

hydrogen and nanoporous materials for hydrogen storage applications. 

Andrea then performed postdoctoral work at the Massachusetts 

Institute of Technology, first as a Rocca Fellow in the Department of 

Material Science and Engineering, studying the phase separation of 

molecules self assembled on metal nanoparticles and their effect on 

the nanoparticles’ solubility. He continued his postdoctoral work in 

the Department of Chemical Engineering, investigating the use of 

metal-organic framework materials for separating small molecules, 

and gold nanorods for in vivo cancer detection and treatment. In 

the CNST, Andrea is developing new measurement methods using 

vibrational spectroscopy, including the development of an IRspectrometer with nanoscale spatial resolution.

Justin Dickinson (June 2010) is a NanoFab Process Engineer 

with a B.S. in Aerospace Engineering from the University of 

Florida in Gainesville, FL, where he worked on a variety of design, 

development, and programming projects on the Human Powered 

Submarine Team and in the Intelligent Machine Design Laboratory. 

Justin provides training and process support during the NanoFab’s 

evening operating hours (Monday through Friday, from 3 pm to 

midnight).

Gregg Gallatin (April 2009) is a Project Leader in the 

Nanofabrication Research Group with a B.S. and Ph.D. in Physics 

from Penn State. After earning his Ph.D., Gregg spent several years 

working in academia and then transitioned to industry, where he 

did research at Perkin-Elmer, SVG Lithography, Bell Labs and IBM. 

While working in industry, Gregg specialized in analysis, modeling 

and design of the systems, subsystems and processes associated 

with the lithographic fabrication of semiconductor devices. He 

holds 12 U.S. patents and has over 60 publications. Gregg’s CNST 

research is focused on the modeling and analysis of the physics of 

self-assembly.

Paul Haney (December 2010) is a Project Leader in the Energy 

Research Group. He received a B.S. in Physics and Mathematics 

from The Ohio State University, and a Ph.D. in Physics from The 

University of Texas at Austin. His thesis focused on first-principles 

calculations of electron and spin transport in magnetic and 

antiferromagnetic multilayers. Paul spent two years as an NRC 

Postdoctoral Research Associate in the Electron Physics Group, 

where he worked with Mark Stiles on the theory of spin transfer 

torque in magnetic semiconductors and in materials near their 

Curie temperature. He moved to the Energy Research Group in 

2009. Paul’s current research includes the effects of disorder 

in materials used for renewable energy, specifically applied to 

organic photovoltaics and thermoelectrics.

Chester Knurek (December 2009) is a NanoFab Process 

Engineer with a B.S. in Electronics Engineering from DeVry 

University in Chicago, IL. Prior to joining NIST, he worked at 

AT&T Microelectronics/Lucent Technologies - Bell Labs on 

characterization and process development for several mask 

formats, including binary/phase-shift photo masks, point source 

X-ray, and flood electron beam. He also has experience developing 

instrumentation to characterize membrane stress uniformity. 

PERSONNEL HIGHLIGHTS
2010 | 7 1

Chester is responsible for training and process support for NanoFab 

users in various nanofabrication areas, including optical lithography 

and metrology.

Vincent Luciani (November, 2008) is the CNST’s NanoFab Manager, 

with over 30 years of private industry experience in semiconductor 

and nanotechnology process development and project management. 

Vincent began his career at Solarex Corp. producing photovoltaic 

solar cells. He then joined the Bendix Advanced Technology Center, 

developing electronic and nanotechnology devices and processes 

in a variety of semiconductor material systems, including silicon, 

gallium arsenide, indium phosphide and lithium niobate. When Bendix 

became part of Allied-Signal, Vincent went on to lead their advanced 

process development team, and was awarded an Allied-Signal Premier 

Achievement Award for excellence in Engineering. Prior to joining 

NIST, he led the process and product engineering teams at Covega 

Corporation, developing and ramping up the production of novel 

indium phosphide photonic devices. Vincent is an expert in Project 

Management, with a Six Sigma Blackbelt, and holds five patents in 

semiconductor and nanofabrication technology.

Ann Smith (January 2009) was a NanoFab Process Engineer until July 

2010. She had a B.A. in Environmental Studies at the University of 

Maryland, Baltimore County with a focus in health and conservation, 

and extensive laboratory experience. In the NanoFab, Ann provided 

training and process support in various areas, including optical 

photolithography, metrology, deposition, and oxidation.

Alline Myers (September 2010) is a Senior Process Engineer in the 

NanoFab, with a B.S. in Physics from North Carolina State University, an 

M.S. in Physics from Penn State, and a Ph.D. in Materials Science and 

Engineering from North Carolina State University. Alline has extensive 

experience in materials and nanostructure characterization using 

field emission scanning TEM, FIB systems, and SEM. After working 

at NIST as an NRC Postdoctoral Research Associate in the Chemical 

Science and Technology Laboratory, Alline spent over 10 years in the 

semiconductor industry, working at Advanced Micro Devices and 

Spansion, where she applied analytical electron microscopy techniques 

to the characterization and failure analysis of logic and flash memory 

devices. Alline is currently responsible for training and assisting 

NanoFab users on the Titan TEM, optimizing the performance of the 

TEM, and helping train users on the dual beam FIB systems.

Fred Sharifi (April 2009) is a Project Leader in the Energy Research Group. 

He received a B. S. in Physics (magna cum laude) from the University of 

Illinois, where he continued his graduate education and received a Ph.D. 

in Condensed Matter Physics. He then performed postdoctoral research 

at Bell Laboratories and at the University of California San Diego, 

studying electronic transport in one-dimensional superconductors and 

tunneling spectroscopy of unconventional superconductors. In 1993, 

Fred became a faculty member at the University of Florida, where he 

was awarded an Alfred Sloan Foundation Fellowship, focusing on 
7 2 | CNST

electronic transport and tunneling in magnetic systems. He joined TRW 

in 2001, working on superconducting electronics, and for the past five 

years was a Principal Scientist at GE Global Research in the Advanced 

Technology Program. Fred’s CNST research is focused on measuring 

nanoscale energy processes in thermoelectrics and photovoltaics.

Renu Sharma (July 2009) is a Project Leader in the Nanofabrication 

Research Group. She received a B.S. and B.Ed. in Physics and Chemistry 

from Panjab University, India, and M.S. and Ph.D. degrees in Solid 

State Chemistry from the University of Stockholm, Sweden, where 

she had a Swedish Institute Fellowship. Renu came to the CNST from 

Arizona State University (ASU), where she most recently served as a 

Senior Research Scientist in the LeRoy Eyring Center for Solid State 

Science and as an affiliated faculty member in the School of Materials 

and Department of Chemical Engineering. Renu has been a pioneer 

in the development of environment-cell TEM, combining atomic-scale 

resolution with dynamic chemical analysis of gas-solid reactions. She 

has applied this powerful implementation of TEM to characterize the 

atomic-scale mechanisms underlying the synthesis and reactivity of 

nanoparticles (including catalysts), nanotubes, nanowires, inorganic 

solids, ceramics, semiconductors, and superconductor materials. Renu 

has received a Deutscher Akademischer Austauschdienst (DAAD) 

Faculty Research Fellowship, is a past President of the Arizona Imaging 

and Microanalysis Society, and has over 140 publications. Renu is 

establishing the CNST’s advanced TEM measurement capabilities for 

nanoscience research and overseeing the operation of a new TEM tool 

in the NanoFab.

Eileen Sparks (February 2009) is a NanoFab Process Engineer with over 

30 years of experience in semiconductor process development, materials 

characterization, and contamination control. Eileen has B.S. and M. 

Ph. degrees in Chemistry from George Washington University. Early in 

her career, she led surface analysis research at Comsat, characterizing 

III-V semiconductor-based materials and devices, including failure 

analysis. She then joined Fusion Systems as a Process Development 

Engineer, developing, installing, and qualifying downstream microwave 

and ozone ashing processes for residue removal in OEMs and foundries 

world-wide. Prior to joining NIST, Eileen worked at ATMI with major 

chipmakers on wafer cleaning and residue removal for CMOS, MEMS, 

and MRAM applications. Eileen is currently assisting the NanoFab with 

base-line process development, FIB training, and industrial outreach.

Veronika Szalai (September 2010) is a Project Leader in the Energy 

Research Group. She received an A.B. in Chemistry from Bryn Mawr 

College, and a Ph.D. in Inorganic Chemistry from Yale University. Her 

thesis work centered on biophysical measurements of water oxidation 

chemistry in natural photosynthesis. After completing postdoctoral 

PERSONNEL HIGHLIGHTS

work at the University of North Carolina at Chapel Hill, Veronika 

spent several years on the faculty in the Department of Chemistry 

and Biochemistry at the University of Maryland Baltimore County. 

During that time, she and her group elucidated the biophysical 

chemistry of copper in Alzheimer’s disease fibrils, investigated the 

effects of DNA condensation on DNA oxidation processes, and 

developed methods to create quadruplex-based DNA materials. 

Veronika is leading CNST projects focused on the fabrication of 

biomimetic nanostructures and on fundamental measurements of 

nanobiomaterials for artificial photosynthesis applications.

A. Alec Talin (July 2009) is a Project Leader in the Energy Research 

Group with a B.A. in Chemistry from the University of California 

at San Diego and a Ph.D. in Materials Science and Engineering 

from the University of California at Los Angeles. After completing 

his postdoctoral work at Sandia National Laboratories, Alec spent 

several years with Motorola Physical Sciences Research Labs, 

first as a staff scientist and subsequently managing the Materials 

Characterization Laboratory. In 2002, Alec returned to Sandia to 

direct and develop programs in nanofabrication, nanoelectronics, 

photonics, and sensing. Alec is leading CNST projects focused 

on fundamental measurements of nanostructured materials in 

electrochemical energy storage.

VISITING FELLOWS

An integral facet of CNST’s dynamic, multidisciplinary research 

environment is the CNST Visiting Fellows program. This program 

is designed to encourage outstanding, senior researchers from 

academic, industrial, and government laboratories world-wide 

to come to NIST to collaborate with CNST’s research staff. 

Researchers selected to be CNST Visiting Fellows may collaborate 

for extended periods via regular, short-term visits, and/or may work 

in residence full-time—for example, during a year-long sabbatical. 

The following researchers have worked at the CNST as Visiting 

Fellows since the start of FY2009, listed alphabetically along with 

their home institutions.

•	 Vladimir Aksyuk, University of Maryland, College Park

•	 Andrea Centrone, University of Maryland, College Park

•	 Kamil Ekinci, Boston University 

•	 John Hartley, University at Albany, SUNY

•	 C. Stephen Hellberg, Naval Research Laboratory

•	 Young Kuk, Seoul National University, Seoul, Korea

•	 Tomohiro Matsui, University of Tokyo, Tokyo, Japan
2010 | 7 3

•	 Jacques Miltat, Université Paris-Sud XI, Paris, France

•	 David R. Penn, NIST Emeritus

•	 Daniel Pierce, NIST Fellow Emeritus

•	 Ben Shapiro, University of Maryland, College Park

•	 Mihaela Tanase, University of Maryland, College Park

•	 John Weiner, Université Paul Sabatier, Toulouse, France

POSTDOCTORAL RESEARCHERS

The CNST has a variety of mechanisms for participating in postdoctoral 

research, with postdoctoral researchers comprising approximately two 

thirds of our research staff. The following researchers have worked at 

the CNST as Postdoctoral Researchers since the start of FY2009, listed 

alphabetically along with their doctoral fields and institutions.

•	 Maxim Abashin, Photonics, University of California, San Diego

•	 Shaffique Adam, Theoretical Physics, Cornell University

•	 Amit Agrawal, Electrical Engineering, University of Utah

•	 Adam Berro, Organic Chemistry, University of Texas at Austin

•	 Sam Bowden, Engineering Sciences-Material Science, Dartmouth 

College

•	 Peter Carmichael, Biochemistry, University of California, San Diego

•	 Jungseok Chae, Physics, Seoul National University, Seoul, Korea

•	 Han-Jong Chia, Physics, University of Texas at Austin

•	 Seok-Hwan Chung, Physics, University of Maryland, College Park

•	 Marcelo Davanço, Electrical and Computer Engineering, University of 

California, Santa Barbara

•	 Zhao Deng, Analytical Chemistry, University of California, Davis

•	 Kan Du, Physics, University of Massachusetts, Amherst

•	 Keith Gilmore, Physics, Montana State University

•	 Behrang Hamadani, Condensed Matter Physics, Rice University

•	 Paul Haney, Physics, University of Texas at Austin

•	 Suyong Jung, Physics, University of Texas at Austin

•	 Raymond Kallaher, Physics, Florida State University

•	 Myung-Gyu Kang, Electrical Engineering, University of Michigan

•	 Nikolai Klimov, Experimental Condensed Matter Physics, Rutgers 

University

•	 Brenton Knuffman, Applied Physics, University of Michigan

•	 Seung-Hyeon (Sarah) Ko, Chemistry, Purdue University
•	 Stephan Koev, Electrical Engineering, University of Maryland, 

College Park

•	 Niv Levy, Physics, University of California at Berkeley

•	 Pramod Mathai, Aerospace Engineering, University of Maryland, 

College Park

•	 Stefano Mazzucco, Physics, Université Paris-Sud XI, Paris, France

•	 Matthew McMahon, Physics, Vanderbilt University

•	 Ben McMorran, Physics, University of Arizona

•	 Houxun Miao, Electrical Engineering, Purdue University

•	 Hongki Min, Physics, University of Texas at Austin

•	 Sander Otte, Physics, Leiden University, Leiden, The Netherlands

•	 Sukumar Rajauria, Physics, University of Joseph Fourier/Neel, 

Grenoble, France

•	 Matthew Rakher, Physics, University of California, Santa Barbara

•	 Gregory Rutter, Physics, Georgia Institute of Technology

•	 Dmitry Ruzmetov, Physics, Indiana University

•	 Young Jae Song, Physics, Seoul National University, Seoul, Korea

•	 Adam Steele, Physics, Georgia Institute of Technology

•	 Gila Stein, Chemical Engineering, University of California, Santa 

Barbara

•	 Ceren Susut, Chemistry, Georgetown University

•	 Hua Xu, Applied Physics, University of Maryland, College Park

•	 Tong Zhang, Physics, Institute of Physics at the Chinese Academy of 

Sciences

•	 Meng Zhu, Experimental Condensed Matter Physics, Penn State 

University

PERSONNEL HIGHLIGHTS

7 4 | CNST

S T U D E N T R E S E A R C H E R S A N D S U M M E R 

U N D E R G R A D U A T E R E S E A R C H F E L L O W S 

The CNST’s collaborative approach to research creates a variety 

of opportunities for students to participate in hands-on research 

under the mentorship of a CNST scientist in our world-class 

laboratories, including the NanoFab and its cleanroom. We 

especially encourage undergraduate science and engineering 

majors interested in nanotechnology to participate in the Summer 

Undergraduate Research Fellowship (SURF) program at NIST, 

which offers the opportunity for a student to spend 11 weeks 

during the summer participating in full-time research at NIST. The 

following students have worked at the CNST since the start of 

FY2009, listed alphabetically along with their home institutions, 

with the SURF participants listed subsequently.

•	 Katherine Freeman, high school intern, Poolesville High School 

Magnet Program

•	 Elizabeth Golovatski, graduate student, Department of Physics 

and Astronomy, University of Iowa

•	 Wesley Hillard, high school intern, Poolesville High School 

Magnet Program

•	 Parakh Jain, high school intern, Poolesville High School Magnet 

Program

•	 Jaime Javier Juarez, graduate student, Department of Chemical 

and Biomolecular Engineering, Johns Hopkins University

•	 Timothy Lee, undergraduate, University of Maryland, College 

Park

•	 Isaac Moreyra, undergraduate, University of Maryland, College 

Park

•	 Michael Rahimi, undergraduate, University of Maryland, 

Baltimore County

•	 Pedram Roushan, graduate student, Physics Department, 

Princeton University

•	 Jungpil Seo, graduate student, Physics Department, Princeton 

University

•	 Rebecca Thomas, graduate student, Department of Electrical 

and Computer Engineering, North Carolina State University

•	 Charles Yeh, high school intern, Poolesville High School Magnet 

Program

•	 Chenyu Zhao, high school intern, Blair High School Magnet 

Program
2010 | 7 5

200 9 SURF

•	 Jason Bylsma, University of South Florida

•	 Suehyun Cho, University of Maryland, College Park

•	 Aaron Cochran, University of Wisconsin-Stout

•	 Timothy Enright, University of the Sciences in Philadelphia

•	 Christopher Hong, Pennsylvania State University

•	 Robert Hoyt, Harvey Mudd College

•	 Joshua Leibowitz, University of Connecticut

•	 Nicole Messier, George Washington University

•	 Gregory Meyer, University of Maryland, College Park

•	 Karthik Prakhya, University of Massachusetts 

•	

•	

•	

•	

•	

•	

•	

20 1 0 SURF

•	 Philip Campbell, University of Texas at Dallas

•	 Olivia Hoff, University of Southern Mississippi

•	 Robert Hoyt, Harvey Mudd College

•	 Joshua Leibowitz, University of Connecticut

•	 Ramsey Noah, California State University Long Beach

•	 Brian Soe, Harvey Mudd College

•	 Mathew Swisher, Carnegie Mellon University

•	 Martin Vilarino, University of Maryland

•	 Richard Webb, University of Texas at Austin
CNST Staff Honors and Awards

Honors and awards received by CNST staff members, including 

postdoctoral researchers and students, during FY2009, FY2010, and the 

first quarter of FY2011 (December 31, 2010) are listed below in reverse 

chronological order. Additional information is provided for the most 

significant awards.

Joseph Stroscio, Fellow, American Association for the Advancement 

of Science (AAAS), 2010. For 2010, 503 AAAS members were chosen 

for this honor by their peers in recognition of scientifically or socially 

distinguished efforts to advance science or its applications. Stroscio 

was elected as an AAAS Fellow as part of the Physics Section for his 

“distinguished contributions to the fields of surface and condensed 

matter physics, particularly for the development and application of 

scanning tunneling microscopy.”

Parakh Jain, Semifinalist, Intel Science Talent Search, December 

2010. Jain, a senior in the Math, Science, and Computer Science 

Magnet Program at Poolesville High School and student intern in the 

Electron Physics Group, was one of 300 semifinalists selected from 

1744 applicants. Jain’s application described calculations of the 

transport properties of multilayer graphene performed in collaboration 

with NRC Postdoctoral Research Associate Shaffique Adam and NIST 

Fellow Mark Stiles.

Henri Lezec, Julius Springer Prize for Applied Physics, October 2010.

Lezec shared this prestigious award with Federico Capasso, Robert L. 

Wallace Professor of Applied Physics and Vinton Hayes Senior Research 

Fellow in Electrical Engineering at Harvard. The prize recognizes 

researchers who have made an outstanding and innovative contribution 

to the fields of applied physics, and recognized Lezec for his “pioneering 

achievements in nanoscale physics and applications.”

Mark Stiles, “Outstanding Referee” for Physical Review, March 2010. 

This lifetime APS award was initiated in 2008 “to recognize scientists 

who have been exceptionally helpful in assessing manuscripts for 

publication in the APS journals.” The status is conferred annually 

to fewer than one percent of the 42,000-strong referee pool, and is 

awarded to show appreciation for the essential work that anonymous 

peer reviewers do for the journals.

Shaffique Adam, NIST Sigma Xi Postdoctoral Best Poster Award, 

March 2010.

PERSONNEL HIGHLIGHTS

7 6 | CNST

Joe Stroscio, AVS Nanometer-Scale Science and Technology 

Division Nanotechnology Recognition Award, November 2009. 

This award recognizes outstanding scientific and technical 

contributions in the science of nanometer-scale structures, 

technology transfer involving nanometer-scale structures, and/or 

the promotion and dissemination of knowledge and development 

in these areas. Stroscio was recognized “for his pioneering 

development of instrumentation to create and characterize 

nanostructures enabling fundamental insights into the mechanisms 

of atom manipulation and the magneto-electric properties of lowdimensional structures.” 

Robert McMichael, Fellow, American Physical Society, November 

2009, awarded for “broad contributions to the measurement, 

modeling, interpretation, and understanding of magnetization 

dynamics.” 

Robert McMichael, Department of Commerce, Silver Medal 

Award, November 2009.

Mark Stiles, NIST Fellow, June 2009.
2010 | 7 7

Alan Band, NIST Sigma Xi Award for Outstanding Services to 

NIST Research Scientists, May 2009. The NIST Chapter of Sigma 

Xi recognized Band for instrumentation solutions that made many 

programs productive throughout NIST and, on occasion, at other 

federal organizations, including contributions to a science display at the 

Smithsonian American History Museum.

Greg Rutter, Best Ph.D. Thesis Award by the Georgia Institute of 

Technology Chapter of Sigma Xi, April 2009. This award recognized 

Rutter’s thesis, “Atomic Scale Properties of Epitaxial Graphene Grown 

on SiC(0001),” which was completed under the direction of Professor 

Phillip First in the School of Physics, with the majority of the research 

performed at the CNST under the guidance of Joseph Stroscio.

Dan Pierce, “Outstanding Referee” for Physical Review, March 2009. 

See award description above for Stiles.

Gregory Rutter, AVS Dorothy M. and Earl S. Hoffman Award, October 

2008. The AVS recognized Rutter for continuing excellence in graduate 

studies in the sciences and technologies of interest to AVS for his 

doctoral research done at the CNST in collaboration with the Georgia 

Institute of Technology.
Research Participant Publications

One measure of the impact of CNST as a national user facility is the publications 

by CNST Research Participants; those working directly on CNST staff projects, 

NanoFab projects, or through a grant from the CNST. The publications associated 

with NanoFab projects and grant research are listed for FY2009 and FY2010. 

The publications authored by CNST staff members are first listed separately, 

and include those published and in press through the first quarter of FY2011 

(December 31, 2010). Published papers are listed in reverse chronological order.

C N S T S T A F F P U B L I C A T I O N S 

(FY 200 9–FY 20 11:Q1)

1. Atomic-level stick-slip, R. W. Carpick and R. J. Cannara, in Encyclopedia 

of Tribology, in press.

2. Effect of alternating Ar and SF6/C4F8 gas flow in Si nano-structure plasma 

etching, L. Chen, V. Luciani, and H. Miao, Microelectronic Engineering, 

in press.

3. Electronic structure of multilayer graphene, H. Min, in Graphene 

Nanoelectronics: Metrology, Synthesis, Properties and Applications, 

edited by H. Raza (Springer, 2011), in press.

4. Electron transport in two dimensional graphene, S. Das Sarma, S. Adam, 

E. Hwang and E. Rossi, Review of Modern Physics, in press.

5. Feedback control of micro-flows, M. Armani, Z. Cummins, J. Gong, 

P. Mathai, R. Probst, C. Ropp, E. Waks, S. Walker, and B. Shapiro, in 

Feedback Control Systems for Micro- and Nano-Scales: MEMS to Atoms, 

edited by J. Gorman and B. Shapiro (Springer, 2011), in press.

6. First-principles study of defect migration in RE-doped ceria (RE = Pr, Gd), 

R. Sharma, P. Dholabhai, J. B. Adams, and P. Crozier, in Next-Generataion 

Fuel Cells—New Materials and Concepts, Proceedings of the Material 

Research Society, Vol. 1311 (Boston, MA), in press. 

7. Graphene carrier transport theory, S. Adam, in Graphene Nanoelectronics: 

Metrology, Synthesis, Properties and Applications, edited by H. Raza 

(Springer, 2011), in press. 

8. Micro-optical techniques, K. Srinivasan, M. T. Rakher, and M. Davanco, 

in Optical Techniques for Materials Characterization (Taylor and Francis), 

in press. 

9. Nanoscale friction: measurement and analysis, R. J. Cannara, in Microand Nano Scale Phenomena in Tribology, in press.

10. Perspective on probing metallic ferromagnetism with electrons, D. T. 

Pierce, Journal of Applied Physics, in press.

11. Plasma etching uniformity control for making large and thick dual-focus 

zone plates, L. Chen, Q. Wang, and U. Griesmann, Microelectronic 

Engineering, in press.

12. Reversal of patterned Co/Pd Multilayers with graded magnetic 

anisotropy, J. E. Davies, P. Morrow, C. L. Dennis, J. W. Lau, B. McMorran, 

A. Cochran, J. Unguris, R. K. Dumas, P. Greene and Kai Liu, Journal of 

Applied Physics 109 (2011), in press.

13. Electron-beam-induced growth of TiO2 nanostructures, S. W. Chee, S. 

Sivaramakrishnan, R. Sharma, and J. Zuo, Microscopy and Microanalysis 

17, 274-278 (2011). 

7 8 | CNST

14. Metal–insulator–metal surface plasmon polariton waveguide 

filters with cascaded transverse cavities, L. O. Diniz, F. D. Nunes, 

E. Marega, J. Weiner, and B. V. Borges, Journal of Lightwave 

Technology 29, 714-720 (2011). 

15. Evolution of microscopic localization in graphene in a magnetic 

field: from scattering resonances to quantum dots, S. Jung, G. M. 

Rutter, N. N. Klimov, D. B. Newell, I. Calizo, A. R. Hight-Walker, N. 

B. Zhitenev, and J. A. Stroscio, Nature Physics 7, 245-251 (2011).

16. Effect of interactions on edge property measurements in magnetic 

multilayers, M. Zhu and R. D. McMichael, Journal of Applied 

Physics 109, 04PDF3904 (2011). 

17. Ordered metal nanostructure self-assembly using metal–organic 

frameworks as templates, B. W. Jacobs, R. J. T. Houk, M. R. Anstey, 

S. D. House, I. M. Robertson, A. A. Talin, and M. D. Allendorf, 

Chemical Science 2, 411-416 (2011).

18. Enhanced magnetization drift velocity and current polarization in 

CoFe1−xGex alloys, M. Zhu, B. D. Soe, R. D. McMichael, M. J. 

Carey, S. Maat, and J. R. Childress, Applied Physics Letters 98, 

072510 (2011).

19. Effects of disorder on magnetic vortex gyration, H. Min, R. D. 

McMichael, J. Miltat, and M. D. Stiles, Physical Review B 83, 

064411 (2011).

20. Optomechanical transduction of an integrated silicon cantilever 

probe using a microdisk resonator, K. Srinivasan, H. Miao, M. T. 

Rakher, M. Davanco, and V. Aksyuk, Nano Letters 11, 791-797

(2011).

21. Simultaneous positioning and orientation of a single nano-object 

by flow control: theory and simulations, P. P. Mathai, A. J. Berglund, 

J. Alexander Liddle, and B. A. Shapiro, New Journal of Physics 13, 

013027 (2011). 

22. Fiber-based cryogenic and time-resolved spectroscopy of PbS 

quantum dots, M. T. Rakher, R. Bose, C. W. Wong, and K. Srinivasan, 

Optics Express 19, 1786-1793 (2011). 

23. Electron vortex beams with high quanta of orbital angular 

momentum, B. J. McMorran, A. Agrawal, I. M. Anderson, A. A. 

Herzing, H. J. Lezec, J. J. McClelland, and J. Unguris, Science 331, 

192 -195 (2011). 

24. Cubic silsesquioxanes as a green, high-performance mold material 

for nanoimprint lithography, H. W. Ro, V. Popova, L. Chen, A. M. 

Forster, Y. Ding, K. J. Alvine, D. J. Krug, R. M. Laine, and C. L. Soles, 

Advanced Materials 23, 414-420 (2011). 

25. A 10 mK scanning probe microscopy facility, Y. J. Song, A. F. Otte, V. 

Shvarts, Z. Zhao, Y. Kuk, S. R. Blankenship, A. Band, F. M. Hess, and 

J. A. Stroscio, Review of Scientific Instruments 81, 121101 (2011). 

26. Nanofabrication techniques for controlled drug released devices, L. 

Chen, G. Henein, and V. Luciani, Nanomedicine 6, 1-6 (2011). 

27. Efficiency enhancement of copper contaminated radial p-n junction 

solar cells, A. Boukai, P. Haney, A. Katzenmeyer, G. M. Gallatin, A. 

A. Talin, and P. Yang, Chemical Physics Letters 501, 153-158 (2011). 

PUBLICATIONS
2010 | 7 9

28. Effect of resist on the transfer of line-edge roughness spatial metrics 

from mask to wafer, P. P. Naulleau and G. M. Gallatin, Journal of Vacuum 

Science & Technology B: Microelectronics and Nanometer Structures 28, 

1259 (2010). 

29. High-frequency nanofluidics: a universal formulation of the fluid dynamics 

of MEMS and NEMS, K. L. Ekinci, V. Yakhot, S. Rajauria, C. Colosqui, and 

D. M. Karabacak, Lab on a Chip 10, 3013-3025 (2010). 

30. Focused chromium ion beam, A. V. Steele, B. Knuffman, J. J. McClelland, 

and J. Orloff, Journal of Vacuum Science and Technology B 28, C6F1-

C6F5 (2010).

31. Quantum transduction of telecommunications-band single photons 

from a quantum dot by frequency upconversion, M. T. Rakher, L. Ma, O. 

Slattery, X. Tang, and K. Srinivasan, Nature Photonics 4, 786-791 (2010). 

32. Contact resistance of flexible, transparent carbon nanotube films with

metals, H. Xu, L. Chen, L. Hu, and N. Zhitenev, Applied Physics Letters

97, 143116 (2010). 

33. Atomistic factors governing adhesion between diamond, amorphous 

carbon, and model diamond nanocomposite surfaces, P. L. Piotrowski,, R. 

J. Cannara, G. Gao, J. J. Urban, R. W. Carpick, and J. A. Harrison, Journal 

of Adhesion Science and Technology 24, 2471-2498 (2010).

34. Epitaxial graphene electronic structure and transport, W. A. de Heer, C. 

Berger, X. Wu, M. Sprinkle, Y. Hu, M. Ruan, J. A. Stroscio, P. N. First, 

R. Haddon, B. Piot, C. Faugeras, M. Potemski, and J. Moon, Journal of 

Physics D: Applied Physics 43, 374007 (2010). 

35. Spatial coherence in electron-beam patterning, G. M. Perera, G. E. Stein, 

and J. A. Liddle, Journal of Vacuum Science & Technology B 28, 1048

(2010). 

36. High-resolution tunnelling spectroscopy of a graphene quartet, Y. J. 

Song, A. F. Otte, Y. Kuk, Y. Hu, D. B. Torrance, P. N. First, W. A. de Heer, H. 

Min, S. Adam, M. D. Stiles, A. H. MacDonald, and J. A. Stroscio, Nature

467, 185-189 (2010). 

37. Real-space mapping of magnetically quantized graphene states, 

D. L. Miller, K. D. Kubista, G. M. Rutter, M. Ruan, W. A. de Heer, M. 

Kindermann, P. N. First, and J. A. Stroscio, Nature Physics 6, 811-817

(2010). 

38. Quantum dots precisely placed by controlled flow, J. A. Liddle, InterNano, 

August 24, 2010.

39. A spray drying system for synthesis of rare-earth doped cerium oxide 

nanoparticles, V. Sharma, K. M. Eberhardt, R. Sharma, J. B. Adams, and 

P. A. Crozier, Chemical Physics Letters 495, 280-286 (2010). 

40. Depth profiling magnetic structure using scanning electron microscopy 

with polarization analysis (SEMPA), B. McMorran, D. Pierce, and J. 

Unguris, Microscopy and Microanalysis 16, 1862-1863 (2010). 

41. Temperature dependence of the diffusive conductivity of bilayer graphene, 

S. Adam and M. D. Stiles, Physical Review B 82, 075423 (2010). 

42. Polymer-assisted conformal coating of TiO2 thin films, E. S. Gillman, D. 

Costello, M. Moreno, A. Raspopin, R. Kasica, and L. Chen, Journal of 

Applied Physics 108, 044310 (2010). 

43. Current-induced torques in the presence of spin-orbit coupling, P. M. 

Haney and M. D. Stiles, Physical Review Letters 105, 126602 (2010). 

44. Statistics of camera-based single-particle tracking, A. J. Berglund, 

Physical Review E 82, 011917 (2010). 

45. The NIST Center for Nanoscale Science and Technology: supporting US 

innovation in nanotechnology, R. Celotta, in Micro/Nano Symposium 

(UGIM), 2010 18th Biennial University/Government/Industry (2010), p. 

1-3.

46. Band structure of ABC-stacked graphene trilayers, F. Zhang, B. Sahu, H. 

Min, and A. H. MacDonald, Physical Review B 82, 035409 (2010).

47. Influence of band parameters on spin-transfer torque in tunnel junctions: 

model calculations, A. H. Khalil, M. D. Stiles, and C. Heiliger, IEEE 

Transactions on Magnetics 46, 1745-1747 (2010). 

48. Effects of edge magnetism and external electric field on energy gaps in 

multilayer graphene nanoribbons, B. Sahu, H. Min, and S. K. Banerjee, 

Physical Review B 82, 115426 (2010).

49. Edge structure of epitaxial graphene islands, G. M. Rutter, N. P. Guisinger, 

J. N. Crain, P. N. First, and J. A. Stroscio, Physical Review B 81, 245408

(2010).

50. Theoretical model of errors in micromirror-based three-dimensional 

particle tracking, A. J. Berglund, M. D. McMahon, J. J. McClelland, and 

J. A. Liddle, Optics Letters 35, 1905-1907 (2010). 

51. Nanoparticle size and shape evaluation using the TSOM optical 

microscopy method, R. Attota, R. M. Silver, A. Vladar, R. Kasica, L. Chen, 

and P. Kavuri, in Proceedings of the Microtech Conference & Expo 2010

(NSTI-Nanotech 2010, 2010), p. 172-175. 

52. Manipulating quantum dots to nanometer precision by control of flow, C. 

Ropp, R. Probst, Z. Cummins, R. Kumar, A. J. Berglund, S. R. Raghavan, E. 

Waks, and B. Shapiro, Nano Letters 10, 2525-2530 (2010). 

53. Effects of disorder and internal dynamics on vortex wall propagation, 

H. Min, R. D. McMichael, M. J. Donahue, J. Miltat, and M. D. Stiles, 

Physical Review Letters 104, 217201 (2010). 

54. Modification of edge mode dynamics by oxidation in Ni80 Fe20 thin film 

edges, M. Zhu and R. D. McMichael, Journal of Applied Physics 107, 

103908 (2010). 

55. Anisotropic damping of the magnetization dynamics in Ni, Co, and Fe, K. 

Gilmore, M. D. Stiles, J. Seib, D. Steiauf, and M. Fahnle, Physical Review 

B 81, 174414 (2010). 

56. (Invited) Three-dimensionally structured thin film heterojunction 

photovoltaics on interdigitated back-contacts, D. Josell, C. Beauchamp, 

B. H. Hamadani, S. Jung, J. Guyer, A. Motayed, C. Hangarter, N. GergelHackett, H. Xu, and N. Zhitenev, ECS Transactions 28, 521-532 (2010).

57. Temperature dependence of magnetization drift velocity and current 

polarization in Ni80

 Fe20 by spin-wave doppler measurements, M. Zhu, C. 

L. Dennis, and R. D. McMichael, Physical Review B 81, 140407 (2010). 

58. Origin of nanoscale variations in photoresponse of an organic solar cell, 

B. H. Hamadani, S. Jung, P. M. Haney, L. J. Richter, and N. B. Zhitenev, 

Nano Letters 10, 1611-1617 (2010). 
75. Critical challenges for picoTesla magnetic-tunnel-junction 

sensors, W. F. Egelhoff, P. W. T. Pong, J. Unguris, R. D. McMichael, 

E. R. Nowak, A. S. Edelstein, J. E. Burnette, and G. A. Fischer, 

Sensors and Actuators A 155, 217-225 (2009).

76. Making Mn substitutional impurities in InAs using a scanning 

tunneling microscope, Y. J. Song, S. C. Erwin, G. M. Rutter, P. N. 

First, N. B. Zhitenev, and J. A. Stroscio, Nano Letters 9, 4333-4337

(2009). 

77. Magnetic dynamics with spin-transfer torques near the Curie 

temperature, P. M. Haney and M. D. Stiles, Physical Review B 80, 

094418 (2009). 

78. Spin transfer torques by point-contact spin injection, T. Y. Chen, 

Y. Ji, S. X. Huang, C. L. Chien, and M. D. Stiles, in Proceedings of 

SPIE (San Diego, CA, USA, 2009), p. 73980C-73980C-12. 

79. Fiber-coupled semiconductor waveguides as an efficient optical 

interface to a single quantum dipole, M. Davanco and K. 

Srinivasan, Optics Letters 34, 2542-2544 (2009). 

80. Spin transfer torques (erratum), D. C. Ralph and M. D. Stiles, 

Journal of Magnetism and Magnetic Materials 321, 2508-2508

(2009). 

81. Efficient spectroscopy of single embedded emitters using optical 

fiber taper waveguides, M. Davanco and K. Srinivasan, Optics 

Express 17, 10542-10563 (2009). 

82. Three dimensionally structured CdTe thin-film photovoltaic 

devices with self-aligned back-contacts: electrodeposition on 

interdigitated electrodes, D. Josell, C. R. Beauchamp, S. Jung, 

B. H. Hamadani, A. Motayed, L. J. Richter, M. Williams, J. E. 

Bonevich, A. Shapiro, N. Zhitenev, and T. P. Moffat, Journal of the 

Electrochemical Society 156, H654-H660 (2009). 

83. Single-photon sources: quantum dots may hold the key to secure 

quantum cryptography, M. T. Rakher, Laser Focus World 45, 63-68

(2009). 

84. Direct imaging of current-driven domain walls in ferromagnetic 

nanostripes, W. C. Uhlig, M. J. Donahue, D. T. Pierce, and J. 

Unguris, Journal of Applied Physics 105, (2009). 

85. Observing the quantization of zero mass carriers in graphene, D. 

L. Miller, K. D. Kubista, G. M. Rutter, M. Ruan, W. A. de Heer, P. N. 

First, and J. A. Stroscio, Science 324, 924-927 (2009). 

86. Spin dynamics and mode structure in nanomagnet arrays: effects 

of size and thickness on linewidth and damping, J. M. Shaw, T. J. 

Silva, M. L. Schneider, and R. D. McMichael, Physical Review B

79, (2009). 

87. The physics of light transmission through subwavelength 

apertures and aperture arrays, J. Weiner, Reports on Progress in 

Physics 72, 064401 (2009). 

88. 2008 International conference on nanoscience and technology, J. 

A. Stroscio and L. J. Whitman, eds. , Journal of Vacuum Science 

& Technology B 27, 784-784 (2009). 

PUBLICATIONS

8 0 | CNST

59. DNA origami used to assemble nanoplasmonic structure, J. A. Liddle, 

InterNano, April 9, 2010. 

60. Epitaxial graphenes on silicon carbide, P. N. First, W. A. de Heer, T. Seyller, 

C. Berger, J. A. Stroscio, and J. Moon, Materials Research Bulletin 35, 

296-305 (2010). 

61. Structural analysis of multilayer graphene via atomic moiré 

interferometry, D. L. Miller, K. D. Kubista, G. M. Rutter, M. Ruan, W. A. de 

Heer, P. N. First, and J. A. Stroscio, Physical Review B 81, 125427 (2010). 

62. Hybrid gap modes induced by fiber taper waveguides: application in 

spectroscopy of single solid-state emitters deposited on thin films, K. 

Srinivasan and M. Davanco, Optics Express 18, 10995-11007 (2010). 

63. Nanostructured solar cells have improved charge collection and selfcleaning properties, F. Sharifi, Internano, February 8, 2010. 

64. Simultaneous measurement of magnetic vortex polarity and chirality 

using scanning electron microscopy with polarization analysis (SEMPA), 

S. Chung, D. Pierce, and J. Unguris, Ultramicroscopy 110, 177-181 (2010). 

65. Going eight separate ways, S. Adam, Physics 3, 12 (2010). 

66. Transport characterization in nanowires using an electrical nanoprobe, 

A. A. Talin, F. Leonard, A. M. Katzenmeyer, B. S. Swartzentruber, S. T. 

Picraux, M. E. Toimil-Molares, J. G. Cederberg, X. Wang, S. D. Hersee, 

and A. Rishinaramangalum, Semiconductor Science and Technology 25, 

024015 (2010). 

67. Phase diagram of magnetic nanodisks measured by scanning electron 

microscopy with polarization analysis, S. Chung, R. D. McMichael, D. T. 

Pierce, and J. Unguris, Physical Review B 81, 024410 (2010). 

68. Effects of magnetism and electric field on the energy gap of bilayer 

graphene nanoflakes, B. Sahu, H. Min, and S. K. Banerjee, Physical 

Review B 81, 045414 (2010). 

69. Measuring the structure of epitaxially assembled block copolymer 

domains with soft X-ray diffraction, G. E. Stein, J. A. Liddle, A. L. Aquila, 

and E. M. Gullikson, Macromolecules 43, 433-441 (2010). 

70. Measuring the effects of low energy ion milling on the magnetization of 

Co/Pd multilayers using scanning electron microscopy with polarization 

analysis, B. J. McMorran, A. C. Cochran, R. K. Dumas, K. Liu, P. Morrow, 

D. T. Pierce, and J. Unguris, Journal of Applied Physics 107, 09D305

(2010). 

71. Spectroscopy of 1.55 μm PbS quantum dots on Si photonic crystal 

cavities with a fiber taper waveguide, M. T. Rakher, R. Bose, C. W. Wong, 

and K. Srinivasan, Applied Physics Letters 96, 161108 (2010). 

72. Controlled deposition of microparticle arrays for LEDs, J. A. Liddle, 

InterNano, December 29, 2009. 

73. An efficient, optical fiber-based waveguide interface to a single quantum 

dipole, M. Davanco and K. Srinivasan, in Frontiers in Optics, OSA 

Technical Digest (CD) (Optical Society of America, San Jose, CA, 2009), 

p. FMG2. 

74. Silver cluster formation, dynamics, and chemistry in metal-organic 

frameworks, R. J. T. Houk, B. W. Jacobs, F. El Gabaly, N. N. Chang, A. A. 

Talin, D. D. Graham, S. D. House, I. M. Robertson, and M. D. Allendorf, 

Nano Letters 9, 3413-3418 (2009).
2010 | 8 1

89. Evaluating the locality of intrinsic precession damping in transition 

metals, K. Gilmore and M. D. Stiles, Physical Review B 79, 132407 (2009). 

90. Exposure of epitaxial graphene on SiC(0001) to atomic hydrogen, N. P. 

Guisinger, G. M. Rutter, J. N. Crain, P. N. First, and J. A. Stroscio, Nano 

Letters 9, 1462-1466 (2009). 

91. Hysteresis loop collapse for linear response in magnetic-tunnel-junction 

sensors, P. W. T. Pong, B. Schrag, A. J. Shapiro, R. D. McMichael, and W. 

F. Egelhoff, Journal of Applied Physics 105, 07E723 (2009). 

92. Imaging response of optical microscopes containing angled micromirrors, 

A. J. Berglund, M. D. McMahon, J. J. McClelland, and J. A. Liddle, in 

Novel Techniques in Microscopy (Optical Society of America, 2009), p. 

NWB5.

93. EUVL dosimetry at NIST, C. Tarrio, S. Grantham, M. Cangemi, R. E. Vest, 

T. B. Lucatorto, and N. Harned, in Alternative Lithographic Technologies

(SPIE, San Jose, CA, USA, 2009), p. 72713X-6. 

94. Reference metrology in a research fab: the NIST clean calibrations thrust, 

R. Dixson, J. Fu, N. Orji, T. Renegar, A. Zheng, T. Vorburger, A. Hilton, M. 

Cangemi, L. Chen, M. Hernandez, R. Hajdaj, M. Bishop, and A. Cordes, 

Proceedings of SPIE 7272, 727209-727212 (2009). 

95. Origin of universal optical conductivity and optical stacking sequence 

identification in multilayer graphene, H. Min and A. H. MacDonald, 

Physical Review Letters 103, 067402 (2009). 

96. Externally mode-matched cavity quantum electrodynamics with chargetunable quantum dots, M. T. Rakher, N. G. Stoltz, L. A. Coldren, P. M. 

Petroff, and D. Bouwmeester, Physical Review Letters 102, 097403

(2009). 

97. 3D particle trajectories observed by orthogonal tracking microscopy, M. 

D. McMahon, A. J. Berglund, P. Carmichael, J. J. McClelland, and J. A. 

Liddle, ACS Nano 3, 609-614 (2009). 

98. Nonadiabatic spin-transfer torque in real materials, I. Garate, K. Gilmore, 

M. D. Stiles, and A. H. MacDonald, Physical Review B 79, 104416 (2009). 

99. A new connection between electricity and magnetism, R. McMichael and 

M. Stiles, Physics 2, 11 (2009). 

100. Molecular and polymer nanodevices, N. B. Zhitenev, in Frontiers of 

Engineering (The National Academy Press, Washington, D.C., 2009), p. 

53-58. 

101. Bias dependence of magnetic exchange interactions: application to 

interlayer exchange coupling in spin valves, P. M. Haney, C. Heiliger, and 

M. D. Stiles, Physical Review B 79, 054405 (2009). 

102. Implementation of two-dimensional polycrystalline grains in object 

oriented micromagnetic framework, J. W. Lau, R. D. McMichael, and M. 

J. Donahue, Journal of Research of the National Institute of Standards 

and Technology 114, 57-67 (2009). 

103. 400-Fold reduction in saturation field by interlayering, W. F. Egelhoff, J. 

Bonevich, P. Pong, C. R. Beauchamp, G. R. Stafford, J. Unguris, and R. D. 

McMichael, Journal of Applied Physics 105, 013921 (2009). 

104. An out-of-plane experience, K. Srinivasan, Nature Photonics 3, 15-16

(2009). 

105. Super-hydrophobic and/or super-hydrophilic surfaces made by 

plasma process, L. Chen, G. Henein, and J. A. Liddle, in NSTINanotech 2009 Technical Proceedings 1-3 (2009), p. 194-197. 

106. Through-focus scanning and scatterfield optical methods for 

advanced overlay target analysis, R. Attota, M. Stocker, R. Silver, 

A. Heckert, H. Zhou, R. Kasica, L. Chen, R. Dixson, G. Orji, B. Barnes, 

and P. Lipscomb, in Proceedings of SPIE (San Jose, CA, USA, 2009), 

p. 727214-727214-13. 

107. Reply to “comment on ‘adiabatic domain wall motion and LandauLifshitz damping’ “, M. D. Stiles, W. M. Saslow, M. J. Donahue, and 

A. Zangwill, Physical Review B 78, 216402 (2008). 

108. A new spin on the Doppler effect, R. D. McMichael and M. D. 

Stiles, Science 322, 386-387 (2008).

O T H E R R E S E A R C H P A R T I C I P A N T 

PUBLICATIONS (FY 200 9–FY 20 1 0 )

1. Underpotential deposition of Tl on (111)-textured Au: in situ stress 

and nanogravimetric measurements, J. W. Shin, U. Bertocci, and G. 

R. Stafford, The Journal of Physical Chemistry C 114, 17621-17628

(2010).

2. Stability and surface topography evolution in nanoimprinted 

polymer patterns under a thermal gradient, Y. Ding, H. J. Qi, K. J. 

Alvine, H. W. Ro, D. U. Ahn, S. Lin-Gibson, J. F. Douglas, and C. L. 

Soles, Macromolecules 43, 8191-8201 (2010).

3. Fabrication, characterization, and flammability testing of 

multiwalled carbon nanotube layer-by-layer coated polyurethane 

foam, R. D. Davis and Y. Kim, NIST TN - 1674 31 (2010).

4. Thin multi-walled carbon nanotube nanocomposite coatings to 

reduce foam flammability, R. D. Davis and Y. S. Kim, NIST TN - 1676

(2010).

5. In-plane liquid crystalline texture of high-performance 

thienothiophene copolymer thin films, X. Zhang, S. D. Hudson, D. 

M. DeLongchamp, D. J. Gundlach, M. Heeney, and I. McCulloch, 

Advanced Functional Materials 20, 4098-4106 (2010).

6. Thermodynamic underpinnings of cell alignment on controlled 

topographies, Y. Ding, J. Sun, H. W. Ro, Z. Wang, J. Zhou, N. J. Lin, 

M. T. Cicerone, C. L. Soles, and S. Lin-Gibson, Advanced Materials

23, 421-425 (2010).

7. A spray drying system for synthesis of rare-earth doped cerium 

oxide nanoparticles, V. Sharma, K. M. Eberhardt, R. Sharma, J. B. 

Adams, and P. A. Crozier, Chemical Physics Letters 495, 280-286

(2010).

8. Image processing and quantification in FIB reconstruction. Tin 

whisker and hillock case study, M. Marsh, M. Williams, K. Moon, 

and W. Boettinger, Microscopy and Microanalysis 16, 1832-1833

(2010).

9. Strength distribution of single-crystal silicon theta-like specimens, 

M. S. Gaither, F. W. DelRio, R. S. Gates, J. Fuller, and R. F. Cook, 

Scripta Materialia 63, 422-425 (2010).
10. Calibration of ultra-low infrared power at NIST, S. I. Woods, S. M. Carr, 

A. C. Carter, T. M. Jung, and R. U. Datla, in High Energy, Optical, and 

Infrared Detectors for Astronomy IV (SPIE, San Diego, California, USA, 

2010), p. 77421P-8.

11. Charged impurity scattering in bilayer graphene, S. Xiao, J. Chen, S. 

Adam, E. D. Williams, and M. S. Fuhrer, Physical Review B 82, 041406

(2010).

12. Demonstration of a Meissner-effect transition edge sensor, S. I. Woods, 

S. M. Carr, T. M. Jung, A. C. Carter, and R. U. Datla, Journal of Applied 

Physics 108, (2010).

13. Reconnection dynamics for quantized vortices, M. S. Paoletti, M. E. 

Fisher, and D. P. Lathrop, Physica D-Nonlinear Phenomena 239, 1367-

1377 (2010).

14. Resolved sideband emission of InAs/GaAs quantum dots strained 

by surface acoustic waves, M. Metcalfe, S. M. Carr, A. Muller, G. S. 

Solomon, and J. Lawall, Physical Review Letters 105, 037401 (2010).

15. Silicon nanowire-based nonvolatile memory cells: progress and 

prospects, Q. Li, X. Zhu, Y. Yang, D. E. Ioannou, J. S. Suehle, and C. A. 

Richter, in Future Trends in Microelectronics: From Nanophotonics to 

Sensors to Energy (Wiley-IEEE), p. 201-208 (2010).

16. In situ tunneling measurements in a transmission electron microscope 

on nanomagnetic tunnel junctions, J. W. Lau, P. Morrow, J. C. Read, V. 

Hoink, W. F. Egelhoff, L. Huang, and Y. Zhu, Applied Physics Letters 96, 

(2010).

17. Measurement of nanomechanical property of particles in a polymer 

matrix, W. Price and S. Hsu, in Proceedings of the 12th International 

Congress on Mesomechanics (National Taiwan University of Science 

and Technology (NTUST) in Taipei, Taiwan, 2010).

18. A simple method to improve etching uniformity when making phase type 

CGHs on a thick glass substrate, Q. Wang, L. Chen, and U. Griesmann, 

in Proceedings of Optical Fabrication and Testing(OF&T) (OSA Technical 

Digest (CD) (Optical Society of America, 2010), Jackson Hole, WY, 2010), 

p. paper OWA2.

19. Curving nanostructures using extrinsic stress, J. Cho, T. James, and D. H. 

Gracias, Advanced Materials 22, 2320-2324 (2010).

20. Compressive stress effect on the radial elastic modulus of oxidized 

Si nanowires, G. Stan, S. Krylyuk, A. V. Davydov, and R. F. Cook, Nano 

Letters 10, 2031-2037 (2010).

21. Transparent Cu nanowire mesh electrode on flexible substrates 

fabricated by transfer printing and its application in organic solar cells, 

M. Kang, H. J. Park, S. H. Ahn, and L. J. Guo, Solar Energy Materials and 

Solar Cells 94, 1179-1184 (2010).

22. Three dimensional nanofabrication using surface forces, J. Cho, A. 

Azam, and D. H. Gracias, Langmuir 26, 16534-16539 (2010).

23. Stress response to surface alloying and dealloying during underpotential 

deposition of Pb on (111)-textured Au, J. W. Shin, U. Bertocci, and G. R. 

Stafford, Journal of Physical Chemistry C 114, 7926-7932 (2010).

PUBLICATIONS

8 2 | CNST

24. Interfacial segregation in polymer/fullerene blend films for 

photovoltaic devices, D. S. Germack, C. K. Chan, R. J. Kline, D. 

A. Fischer, D. J. Gundlach, M. F. Toney, L. J. Richter, and D. M. 

DeLongchamp, Macromolecules 43, 3828-3836 (2010).

25. More variations on Aharonov-Bohm, P. A. Sturrock and T. R. 

Groves, Physics Today 63, 8 (2010).

26. High performance airbrushed organic thin film transistors, C. 

K. Chan, L. J. Richter, B. Dinardo, C. Jaye, B. R. Conrad, H. W. 

Ro, D. S. Germack, D. A. Fischer, D. M. DeLongchamp, and D. J. 

Gundlach, Applied Physics Letters 96, 133304 (2010).

27. Elastic constants and dimensions of imprinted polymeric nanolines 

determined from Brillouin light scattering, W. L. Johnson, S. A. 

Kim, R. Geiss, C. M. Flannery, C. L. Soles, C. Wang, C. M. Stafford, 

W. Wu, J. M. Torres, B. D. Vogt, and P. R. Heyliger, Nanotechnology

21, 075703 (2010).

28. A facile route to polymer solar cells with optimum morphology 

readily applicable to a roll-to-roll process without sacrificing high 

device performances, H. J. Park, M. Kang, S. H. Ahn, and L. J. Guo, 

Advanced Materials 22, E247-E253 (2010).

29. (Invited) Metrology of molecular devices made by flip chip 

lamination, C. A. Hacker, M. Coll, and C. A. Richter, ECS 

Transactions 28, 549 (2010).

30. 2D separations on a 1D chip: gradient elution moving boundary 

electrophoresis—chiral capillary zone electrophoresis, D. Ross, J. 

G. Shackman, J. G. Kralj, and J. Atencia, Lab on a Chip 10, 3139

(2010).

31. Characterization of collagen fibrils films formed on 

polydimethylsiloxane surfaces for microfluidic applications, T. A. 

Spurlin, S. P. Forry, G. A. Cooksey, and A. L. Plant, Langmuir 26, 

14111-14117 (2010).

32. Development of an electrolyte-free, oxygen-free, highperformance, single direct methanol fuel cell (DMFC), E. Chen and 

R. Fenkelstein, in Proceedings of 44th Power Sources Conference, 

Las Vegas, NV (2010), p. 333-336.

33. Effects of temperature, acyl chain length, and flow-rate ratio 

on liposome formation and size in a microfluidic hydrodynamic 

focusing device, J. M. Zook and W. N. Vreeland, Soft Matter 6, 

1352 (2010).

34. Image-based feedback control for real-time sorting of 

microspheres in a microfluidic device, M. S. Munson, J. M. Spotts, 

A. Niemistoe, J. Selinummi, J. G. Kralj, M. L. Salit, and A. Ozinsky, 

Lab on a Chip 10, 2402-2410 (2010).

35. In-situ stress measurements during electrodeposition of Au-Ni 

alloys, E. Rouya, G. R. Stafford, C. R. Beauchamp, J. A. Floro, R. G. 

Kelly, M. L. Reed, and G. Zangari, Electrochemical and Solid-State 

Letters 13, D87-D90 (2010).
2010 | 8 3

49. Effect of fluorosurfactant on capillary instabilities in nanoimprinted 

polymer patterns, K. J. Alvine, Y. Ding, J. F. Douglas, H. Wook Ro, B. C. 

Okerberg, A. Karim, K. A. Lavery, S. Lin-Gibson, and C. L. Soles, Journal of 

Polymer Science Part B: Polymer Physics 47, 2591-2600 (2009).

50. The large-scale integration of high-performance silicon nanowire field 

effect transistors, Q. Li, X. Zhu, Y. Yang, D. E. Ioannou, H. D. Xiong, D. 

Kwon, J. S. Suehle, and C. A. Richter, Nanotechnology 20, 415202 (2009).

51. Advanced capacitance metrology for nanoelectronic device 

characterization, C. A. Richter, J. J. Kopanski, C. Jiang, Y. Wang, M. Y. 

Afridi, X. Zhu, D. E. Ioannou, and Q. Li, AIP Conference Proceedings 1173, 

328 (2009).

52. Thermal stability of confined flip-chip laminated ω-functionalized 

monolayers, M. Coll, C. A. Richter, and C. A. Hacker, Journal of Vacuum 

Science & Technology B 27, 2826 (2009).

53. Silicon nanowire NVM with high-k gate dielectric stack, X. X. Zhu, D. Gu, 

Q. Li, D. Ioannou, H. Baumgart, J. Suehle, and C. Richter, Microelectronic 

Engineering 86, 1957-1960 (2009).

54. Formation of silicon-based molecular electronic structures using flipchip lamination, M. Coll, L. H. Miller, L. J. Richter, D. R. Hines, O. D. 

Jurchescu, N. Gergel-Hackett, C. A. Richter, and C. A. Hacker, Journal of 

the American Chemical Society 131, 12451-12457 (2009).

55. Large-area roll-to-roll and roll-to-plate nanoimprint lithography: a step 

toward high-throughput application of continuous nanoimprinting, S. H. 

Ahn and L. J. Guo, ACS Nano 3, 2304-2310 (2009).

56. Microscale polymer-nanotube composites, E. K. Hobbie, J. A. Fagan, J. 

Obrzut, and S. D. Hudson, ACS Applied Materials & Interfaces 1, 1561-

1566 (2009).

57. A molecular beam epitaxy facility for in situ neutron scattering, J. A. Dura 

and J. LaRock, Review of Scientific Instruments 80, 073906 (2009).

58. Multilamellar interface structures in Nafion, J. A. Dura, V. S. Murthi, M. 

Hartman, S. K. Satija, and C. F. Majkrzak, Macromolecules 42, 4769-4774

(2009).

59. Development of the grating phase neutron interferometer at a 

monochromatic beam line, S. W. Lee, D. S. Hussey, D. L. Jacobson, C. M. 

Sim, and M. Arif, Nuclear Instruments and Methods in Physics Research 

Section A 605, 16-20 (2009).

60. Nuclear instruments and methods in physics research section A: 

accelerators, spectrometers, detectors and associated equipment, S. 

W. Lee, D. S. Hussey, D. L. Jacobson, C. M. Sim, and M. Arif, Nuclear 

Instruments and Methods in Physics Research Section A 605, 209-214

(2009).

61. Decoherence-free neutron interferometry, D. A. Pushin, M. Arif, and D. G. 

Cory, Physical Review A 79, 053635 (2009).

62. Ultra-thin SiO2 on Si IX: absolute measurements of the amount of silicon 

oxide as a thickness of SiO2

 on Si, M. P. Seah, W. E. S. Unger, H. Wang, 

W. Jordaan, T. Gross, J. A. Dura, D. W. Moon, P. Totarong, M. Krumrey, R. 

Hauert, and Z. Q. Mo, Surface and Interface Analysis 41, 430-439 (2009).

36. Optical and electrical properties of graphene percolated networks from 

liquid exfoliation of graphite, J. Obrzut, D. Pristinski, and M. Yoonessi, 

ECS Transactions 28, 99-106 (2010).

37. Plasmo-photonic nanowire arrays for large-area surface-enhanced 

Raman scattering sensors, J. D. Caldwell, O. J. Glembocki, R. W. Rendell, 

S. M. Prokes, J. P. Long, and F. J. Bezares, Proceedings of SPIE 7757, 

775723 (2010).

38. Spatially resolved height response of phase-shifting interferometers 

measured using a patterned mirror with varying spatial frequency, J. Chu, 

Q. Wang, J. P. Lehan, G. Gao, and U. Griesmann, Optical Engineering 49, 

095601 (2010).

39. Toward low-cost, high-efficiency, and scalable organic solar cells with 

transparent metal electrode and improved domain morphology, M. Kang, 

H. J. Park, S. H. Ahn, T. Xu, and L. J. Guo, Selected Topics in Quantum 

Electronics, IEEE Journal of 16, 1807-1820 (2010).

40. Silicon nanowire nonvolatile-memory with varying HfO2 charge trapping 

layer thickness, X. Zhu, Qiliang Li, D. Ioannou, D. Gu, H. Baumgart, J. 

Bonevich, J. Suehle, and C. Richter, in Semiconductor Device Research 

Symposium, 2009. ISDRS ‘09. (College Park, MD, 2009), p. 1-2.

41. Self-assembly of lithographically patterned nanoparticles, J. Cho and D. 

H. Gracias, Nano Letters 9, 4049-4052 (2009).

42. Active feedback of a Fabry-Perot cavity to the emission of a single InAs/

GaAs quantum dot, M. Metcalfe, A. Muller, G. S. Solomon, and J. Lawall, 

Journal of the Optical Society of America B 26, 2308-2314 (2009).

43. C60 cluster formation at interfaces with pentacene thin-film phases, B. 

R. Conrad, J. Tosado, G. Dutton, D. B. Dougherty, W. Jin, T. Bonnen, A. 

Schuldenfrei, W. G. Cullen, E. D. Williams, J. E. Reutt-Robey, and S. W. 

Robey, Applied Physics Letters 95, 213302-3 (2009).

44. Measurement of heat capacity and enthalpy of formation of nickel 

silicide using nanocalorimetry, R. K. Kummamuru, L. De La Rama, L. Hu, 

M. D. Vaudin, M. Y. Efremov, M. L. Green, D. A. LaVan, and L. H. Allen, 

Applied Physics Letters 95, (2009).

45. Achieving 1/f noise reduction with the MEMS flux concentrator, A. 

Edelstein, G. Fischer, J. Burnette, W. Egelhoff, and Shu Fan Cheng, in 

Sensors, 2009 IEEE (2009), p. 1852-1855.

46. 200 mm silicon wafer processing for large area strip detectors, M. 

Christophersen and B. F. Phlips, in 2009 IEEE Nuclear Science Symposium 

and Medical Imaging Conference Record (Orlando, Florida, 2009), p. 

1649-1652.

47. Application of ALD high-k dielectric films as charge storage layer and 

blocking oxide in nonvolatile memories, X. Zhu, D. Gu, Q. Li, H. Baumgart, 

D. Ioannou, J. Suehle, and C. Richter, ECS Transactions 25, 473-479

(2009).

48. Planarization of discrete track recording media to improve flyability of 

magnetic recording sliders, Y. Yoon, C. Choi, Y. Oh, D. Hong, S. Jin, and F. 

E. Talke, IEEE Transactions on Magnetics 45, 3527-3530 (2009).
8 4 | CNST

63. Quantifying residual stress in nanoscale thin polymer films via surface 

wrinkling, J. Y. Chung, T. Q. Chastek, M. J. Fasolka, H. W. Ro, and C. M. 

Stafford, ACS Nano 3, 844-852 (2009).

64. A versatile waveguide source of photon pairs for chip-scale quantum 

information processing, J. Chen, A. J. Pearlman, A. Ling, J. Fan, and A. 

Migdall, Optics Express 17, 6727-6740 (2009).

65. Ultrasmooth gold as a top metal electrode for molecular electronic 

devices, M. Coll, C. A. Hacker, L. H. Miller, D. R. Hines, E. D. Williams, 

and C. A. Richter, ECS Transactions 16, 139-146 (2009).

66. Interferometric fluorescent super-resolution microscopy resolves 3D 

cellular ultrastructure, G. Shtengel, J. A. Galbraith, C. G. Galbraith, 

J. Lippincott-Schwartz, J. M. Gillette, S. Manley, R. Sougrat, C. M. 

Waterman, P. Kanchanawong, M. W. Davidson, R. D. Fetter, and H. F. 

Hess, Proceedings of the National Academy of Sciences 106, 3125-3130 

(2009).

67. Ionic current rectification, breakdown, and switching in heterogeneous 

oxide nanofluidic devices, L. J. Cheng and L. J. Guo, ACS Nano 3, 575-

584 (2009).

68. Pentacene islands grown on ultra-thin SiO2, B. Conrad, W. Cullen, B. 

Riddick, and E. Williams, Surface Science 603, L27-L30 (2009).

69. Biphasic GaN nanowires: growth mechanism and properties, J. Halpern, 

A. Bello, J. Gilcrease, G. Harris, and M. He, Microelectronics Journal 40, 

316-318 (2009).

70. Magnetic tunnel junctions with self-assembled molecules, W. Y. Wang 

and C. A. Richter, Journal of Nanoscience and Nanotechnology 9, 1008-

1010 (2009).

71. Fatigue and debris generation at indentation-induced cracks in silicon, S. 

Bhowmick, H. Cha, Y. Jung, and B. R. Lawn, Acta Materialia 57, 582-589

(2009).

72. Geometry transformation and alterations of periodically patterned Si 

nanotemplates by dry oxidation, J. Park, L. H. Chen, D. Hong, C. Choi, M. 

Loya, K. Brammer, P. Bandaru, and S. Jin, Nanotechnology 20, 015303

(2009).

73. Absolute cryogenic radiometer and solid-state trap detectors for IR power 

scales down to 1pW with 0.1 % uncertainty, A. C. Carter, S. I. Woods, S. 

M. Carr, T. M. Jung, and R. U. Datla, Metrologia 46, S146-S150 (2009).

74. Large area high density sub-20 nm SiO2 nanostructures fabricated by 

block copolymer template for nanoimprint lithography, H. J. Park, M. 

Kang, and L. J. Guo, ACS Nano 3, 2601-2608 (2009).

75. Measuring the EUV-induced contamination rates of TiO2 capped 

multilayer optics by anticipated production-environment hydrocarbons, 

S. B. Hill, N. S. Faradzhev, C. S. Tarrio, T. B. Lucatorto, R. A. Bartynski, B. 

V. Yakshinskiy, and T. E. Madey, Proceedings of SPIE 7271, 727113 (2009).

PUBLICATIONS

76. Nanosurfaces for nanosensing, E. Gillman, A. Raspopin, D. 

Costello, M. Moreno, and A. Taylor, Proceedings of SPIE 7318, 

731812 (2009).

77. Optical and conductivity properties of films from liquid-phase 

exfoliation of natural graphite, J. Obrzut and K. B. Migler, ECS 

Transactions 19, 69-73 (2009).

78. PicoWatt infrared power measurement using an absolute 

cryogenic radiometer, S. M. Carr, S. I. Woods, T. M. Jung, A. C. 

Carter, and R. U. Datla, Proceedings of SPIE 7298, 72983Y (2009).

79. Steep subthreshold slope nanowire FETs with gate-induced 

Schottky-barrier tunneling, Qiliang Li, Xiaoxiao Zhu, D. Ioannou, J. 

Suehle, and C. Richter, in Device Research Conference, 2009. DRC 

2009 (2009), p. 113-114.

80. Thick silicon drift detectors, M. Christophersen and B. F. Phlips, in 

Nuclear Science Symposium Conference Record, 2008. NSS ‘08. 

IEEE (2009), p. 2727-2730.

81. Tracking down sources of carbon contamination in EUVL exposure 

tools, C. Tarrio, R. E. Vest, T. B. Lucatorto, and R. Caudillo, 

Proceedings of SPIE 7969, 727112 (2009).

82. Validation of the microelectromechanical system flux concentrator 

concept for minimizing the effect of 1/f noise, A. S. Edelstein, J. 

E. Burnette, G. A. Fischer, K. Olver, W. Egelhoff, E. Nowak, and 

S. Cheng, Journal of Applied Physics 105, 07E720-1 - 07E720-3

(2009).

83. Silicon nanowire NVM cell using high-k dielectric charge storage 

layer, X. Zhu, Y. Yang, Q. Li, D. E. Ioannou, J. S. Suehle, and C. A. 

Richter, Microelectronic Engineering 85, 2403–2405 (2008).

84. Morphology control of carbon nanotubes through focused ion 

beams, M. Loya, J. E. Park, L. H. Chen, K. S. Brammer, P. R. 

Bandaru, and S. Jin, Nano 3, 449-454 (2008).

85. Radius measurement of spherical surfaces with large radii-ofcurvature using dual-focus zone plates, Q. Wang, in Proceedings 

of Optical Fabrication and Testing(OF&T) (OSA Technical Digest 

(CD) (Optical Society of America, 2008), 2008), p. paper OWB2.

86. Metrology for the electrical characterization of semiconductor 

nanowires, C. A. Richter, H. D. Xiong, X. Zhu, W. Wang, V. M. 

Stanford, W. Hong, T. Lee, D. E. Ioannou, and Q. Li, Transactions 

on Electron Devices 55, 3086-3095 (2008).

87. Trenched gamma-ray detector, M. Christophersen, B. F. Phlips, 

and F. J. Kub, in Nuclear Science Symposium Conference Record, 

2008. NSS ‘08. IEEE (2008), p. 2783-2787.
Editors

Denise Rogers, Information Manager

Lloyd Whitman, Deputy Director

Center for Nanoscale Science and Technology

National Institute of Standards and Technology

U.S. Department of Commerce

Gary Locke, Secretary

National Institute of Standards and Technology

Patrick D. Gallagher, Director and Under Secretary of Commerce for Standards and Technology

NIST SP 1121

March 2011

Disclaimer: Certain commercial equipment, and software, are identified in this documentation to describe the subject 

adequately. Such identification does not imply recommendation or endorsement by the National Institute of Standards 

and Technology, nor does it imply that the equipment identified is necessarily the best available for the purpose.
Center for Nanoscale Science and Technology

National Institute of Standards and Technology

100 Bureau Drive, MS 6200

Gaithersburg, MD 20899-6200 USA

(301) 975-8001

WWW.NIST.GOV/CNST