National Institute of 

Standards and Technology

Technology Administration

U.S. Department of Commerce

NISTIR 6601

January 2001

Electronics and Electrical 

Engineering Laboratory

Electromagnetic

Technology

Division

Programs, Activities, and 

Accomplishments
The Electronics and Electrical

Engineering Laboratory

Through its technical laboratory research programs, the

Electronics and Electrical Engineering Laboratory (EEEL)

supports the U.S. electronics industry, its suppliers, and its

customers by providing measurement technology needed to

maintain and improve their competitive position. EEEL also

provides support to the federal government as needed to

improve efficiency in technical operations, and cooperates

with academia in the development and use of measurement

methods and scientific data.

EEEL consists of five programmatic divisions, two matrixmanaged offices, and a special unit concerned with magnetic

metrology:

! Electricity Division

! Semiconductor Electronics Division

! Radio Frequency Technology Division

! Electromagnetic Technology Division

! Optoelectronics Division

! Office of Microelectronic Programs

! Office of Law Enforcement Standards

! Magnetics Group

This document describes the technical programs of the

Electromagnetic Technology Division. Similar documents

describing the other Divisions and Offices are available.

Contact NIST/EEEL, 100 Bureau Drive, MS 8100,

Gaithersburg, MD 20899-8100, Telephone: (301) 975-2220,

On the Web: www.eeel.nist.gov

The cover illustrates the variety of work in the

Electromagnetic Technology Division. Integrated circuit

fabrication underlies all the work of the Division and the

large background photograph shows one of our staff

members making a circuit in our nanoscale fabrication

facility. The left-most micrograph shows a lithographed

antenna coupled to a nanometer-sized diode for rectifying

visible light. The cellular phone may be receiving a call which

passes through a base station which uses high temperature

superconductor filters. The complex chip is a Josephson

series array ac voltage standard.
Electronics and Electrical

Engineering Laboratory

Electromagnetic

Technology

Division

Programs, Activities, and

Accomplishments

NISTIR 6601

January 2001

U.S. DEPARTMENT OF COMMERCE

Norman Y. Mineta, Secretary

Technology Administration

Dr. Cheryl L. Shavers, Under Secretary of Commerce for Technology

National Institute of Standards and Technology

Karen H. Brown, Acting Director

ME

UNITED STATES OF AMERICA

DEPARTMENT OF COM

RCE

 Electromagnetic Technology Division iii

Contents

Welcome .........................................................................................................................iv

Josephson Array Technology............................................................................................. 1

Nanoscale Cryoelectronics................................................................................................. 7

High Performance Sensors, Infrared Detectors, and Mixers ................................................15

High Tc Electronics ..........................................................................................................19

Nanoscale Fabrication......................................................................................................24

Appendix A: Experimental Systems and Instruments .........................................................25

Appendix B: Postdoctoral Opportunities ............................................................................26

Appendix C: Awards and Recognition................................................................................27

Appendix D: Division Staff................................................................................................30

 Electromagnetic Technology Division v

Welcome

The roughly forty staff and guest scientists in the Electromagnetic Technology Division and I

take great pride in bringing you this brief report on recent progress of our Division. We have

a long history of inventing and disseminating new standards and measurement technology.

We focus on exceptional standards and measurement methods using remarkable quantum

effects and low noise available only at temperatures close to absolute zero or –452 oF (0 K).

This book describes some of our recent successes.

It has always been our goal to provide U.S. industry with the best metrology in the world.

We began about thirty years ago to bring the unique capabilities of cryogenic electronic

technology to bear on metrology, the science of measurement. In many cases our technology

enables measurements that are otherwise impossible. We developed what has become the

world’s practical standard of voltage, based on integrated circuits containing tens of

thousands of superconducting Josephson junctions made in our own fabrication facility. We

demonstrated the first capacitance standard based on counting of single electrons. For

materials analysis, we perfected an X-ray spectrometer that combines the best features of

two types of existing detectors and promises to be critical in defect analysis of future

semiconductor devices. This year, NIST’s director, Ray Kammer, dedicated improved clean

room facilities, which are critical to all of our efforts and enable us to produce

microfabricated structures smaller than 100 nanometers.

We have a long tradition of excellence dating back to the formation of our organization in

1969. Our world-leading work has resulted in many prestigious awards to our staff, which

are listed in Appendix C.

Whether you are our customer and use the results of our efforts, or are simply interested in

the remarkable progress our technology brings to measurements, we hope you will find this

report exciting. You will find descriptions of our recent work, lists of our publications, and

descriptions of our postdoctoral research opportunities. For the most up-to-date information,

please visit our Web site, http://emtech.boulder.nist.gov. Our website also contains a

searchable bibliography of all of our publications.

Thank you for your interest in NIST’s Electromagnetic Technology Division.

Richard E. Harris

Division Chief

Electromagnetic Technology Division

National Institute of Standards and Technology

325 Broadway

Boulder, Colorado 80305-3328

(303) 497-3678

http://emtech.boulder.nist.gov

Josephson Array

Technology

Project Goal

To develop superconductive electronic

circuit and system technology for

fundamental, quantum-based dc and

ac voltage standard systems; to

provide improved standards for

fundamental metrology, and support

U.S. industry test and measurement

applications.

Charlie Burroughs and Sam Benz discuss the

operating margins of a pulse-driven Josephsonjunction array.

Customer Needs

The demands of modern technology for

accurate voltage calibrations have

gradually exceeded the capability of

classical artifact standards. To meet

current needs, an international agreement signed in 1990 redefined the

practical volt in terms of the voltage

generated by a superconductive integrated circuit developed at NIST and the

Physikalisch-Technische Bundesanstalt

in Germany. This circuit contains

thousands of superconducting Josephson

junctions, all connected in a series array

and biased at a microwave frequency. In

contrast to artifact standards in which the

value depends upon environmental and

physical factors, the voltage developed

by each junction depends on frequency

and fundamental constants. Thus, a

Josephson array circuit never needs to be

calibrated. This allows any standards or

commercial laboratory to generate

highly accurate voltages without the

need to transfer an artifact standard. This

advance has improved the uniformity of

voltage measurements around the world

by about a hundredfold. These systems

are rapidly becoming essential for

meeting legal and accreditation

requirements in commercial, governmental, and military activities.

The U.S. electronics instrumentation

industry maintains its world position

through the development and deployment of increasingly accurate, flexible,

and easier-to-use instruments. Providing

U.S. industry with quantum voltage

standard systems gives these customers,

with appropriate oversight from the

NIST Electricity Division, immediate

realization of the highest possible inhouse accuracy. These customers also

benefit dramatically by removing their

dependence on less accurate reference

standards that require frequent

calibration.

We also support the standards community by developing voltage standard

systems with new capabilities, including

lower cost, increased functionality, and

ease of use. Other customers are the

superconductive electronics community

and the U.S. military, which we support

through development of novel superconductive circuits and high-performance systems, and by providing

technical expertise and consulting.

Technical Contact:

Samuel P. Benz

benz@boulder.nist.gov

The voltage pulse

developed by each

junction depends on

fundamental constants

and never needs to be

calibrated.

 Electromagnetic Technology Division 1
 2

Charlie Burroughs with 1 V programmable

voltage standard system consisting of (left to

right) low thermal probe, microwave and high

speed bias electronics, and computer control.

Technical Strategy

Over the past 20 years, this project has

developed superconductive Josephsonjunction array technology for quantum

voltage standard systems. Groundbreaking work at NIST led to commercialization of the first practical dc

Josephson voltage standard system.

Recent improvements in system design

and operation have led to a traveling

Josephson voltage standard system that

is compact, of low cost, and transportable for calibration of Zener

reference standards. This technology has

recently been transferred directly to the

private sector.

A 1 cm × 1 cm superconductive integrated

circuit with 32,768 SNS Josephson junctions for

the 1 V programmable voltage standard.

Over the past few years, we have

developed a novel superconductornormal metal-superconductor (SNS)

junction technology that adds the

features of stability and programmability

to the accuracy of conventional Josephson voltage standards. Programmable

Josephson voltage standard systems

based on these junctions have been

delivered and installed in a number of

metrology experiments, namely the watt

balance experiments at NIST and

Switzerland’s Federal Office of Metrology (OFMET) and the metrology triangle experiment at France’s Central

Laboratory for Electrical Industry

(LCIE), where these features should

reduce the uncertainty of the

experimental measurements.

The NIST Electricity Division is

interested in improving the internal

efficiency of its maintenance and

dissemination of NIST-traceable voltage

through the development and deployment of an improved 1 V programmable

voltage standard. We will work with

Electricity Division staff to develop a

Josephson voltage standard that can be

used more directly in the customer’s

calibration system.

We provide systems and support to NIST and

other national metrology laboratories for

Josephson voltage standard systems.

Our present primary goal is to develop

the world’s first quantum-mechanically

accurate voltage source for both ac and

dc metrology. The device is effectively a

digital-to-analog converter capable of

synthesizing arbitrary waveforms using

the perfectly quantized pulses of Josephson junctions. The concept for this new

device was co-invented by NIST and

Northrop-Grumman researchers in 1996.

Present ac voltage standards are

detectors based on ac-dc thermal voltage

converters. A quantum-based ac source

would provide an entirely new instrument and methodology for ac metrology.

Its use as a stable accurate arbitrary

waveform generator would also be

useful for calibration of other scientific

instruments, such as ac voltmeters,

amplifiers, and filters. The major

challenge of this technology is to

achieve practical output voltages by

Groundbreaking

work at NIST led to

commercialization

of the first practical

DC Josephson

voltage standard

system.

Our present primary

goal is to develop

the world’s first

quantum

mechanically

accurate voltage

source for both AC

and DC metrology.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 3

developing improved broadband circuits

and novel submicrometer junctions.

We will develop an ac voltage source with an

output voltage of 1 volt.

Paul Dresselhaus demonstrates a waveform

synthesized with the Josephson arbitrary

waveform generator.

The concept of an arbitrary voltage

waveform generator with quantummechanical accuracy has enabled the

possibility of making an electronically

based thermometer. The quantum-based

waveform generator can be used to

synthesize an equivalent noise voltage

with a known, calculable noise

spectrum. This quantized noise source

can be used to calibrate the correlator

measurement electronics of a Johnson

noise thermometry system. In

collaboration with the Chemical Science

and Technology Laboratory’s Process

Measurements Division, we have been

awarded a competence grant to develop

this new quantum-based electrical

thermometer.

We will develop a quantized voltage noise

source for calibration of a Johnson noise

thermometer

Accomplishments

! First operating margins and record

voltage — We have demonstrated operating margins and a record 127 mV

peak-to-peak (pp) voltage for ac waveforms with the Josephson arbitrary

waveform synthesizer. This device is

capable of digitally synthesizing any

waveform from dc to 100 MHz. We also

measured record low harmonic

distortion, demonstrating the importance

of perfect quantization from superconducting Josephson junctions. We

measured –95 dBc distortion for a 2.8

kHz sine wave and less than –80 dBc

intermodulation at 5 MHz. The improvement in operating margins (previously

zero for ac waveforms) and output

voltage (previously 52 mV pp) are a

result of improved broadband on-chip

filters and a larger array of 4,096

Josephson junctions.

! First ac metrology measurements —

Improved operating margins and a new

circuit design have enabled us to

perform the first ac metrology

measurements of the Josephson arbitrary

waveform synthesizer. Comparisons

were made between ac and dc voltages

synthesized by the Josephson synthesizer. New circuits utilizing lumped

arrays of 250 junctions with on-chip

filtering and a grounded circuit design

enabled direct connection of the array

output voltage to a thermal transfer

standard. Direct connection to measurement instrumentation is required for

optimum performance in calibrations

because it avoids gain and distortion

errors that can be induced by

intermediate amplifiers. From the ac-todc comparisons we concluded that the

repeatability of the ac voltages is good

and that thermal voltages are not a

significant source of error. We also

concluded that we have precise control

of synthesized rms voltages and their

harmonic content.

! New coupling method promises

higher voltages — We have developed a

new ac-coupled input technique that

allows us to use large distributed arrays

of more than 4,000 junctions and

simultaneously maintain the directly

coupled output that is necessary for

metrological measurements. The larger

distributed arrays have larger output

voltage as compared to the previously

used lumped arrays with only 250

junctions. Larger voltages (127 mV pp)

can now be used for both precise

arbitrary waveform synthesis with low

harmonic distortion as well as for precise

rms voltage synthesis for ac metrology.

The larger voltage has enabled 10 times

The concept of an

arbitrary voltage

waveform generator

with quantummechanical accuracy

has enabled the

possibility of making

an electronically

based thermometer.

Improved operating

margins and a new

circuit design have

enabled us to perform

the first ac metrology

measurements of the

Josephson arbitrary

waveform

synthesizer.
4

lower uncertainty for ac-to-ac

comparisons as compared to previous

measurements using lumped arrays. This

technique also has the potential for

significantly higher output voltage by

enabling multiple arrays to be connected

in series.

! Titanium nitride junctions —

Junctions with titanium nitride barriers

are being developed for use in lumped

arrays. Lumped arrays, in which a large

number of junctions are spaced within a

very short distance, are necessary for

increasing the output voltage of the ac

voltage source as well as its range of

output frequencies. TiN was chosen to

replace PdAu as the junction barrier

because it allows us to stack multiple

junctions on top of each other with very

close spacing of a few hundred

nanometers. We have successfully

fabricated our first junctions using TiN

as a barrier material.

Collaborations

! We are collaborating with Blaise

Jeanneret of OFMET, Switzerland. We

have delivered a 1 V chip and a

cryoprobe with low-thermal voltages for

their programmable voltage standard

system. The system is being used in

OFMET’s novel watt balance experiment. To test the system’s functionality,

a comparison was made between their

conventional Josephson voltage standard

and our programmable circuit. The two

systems agreed to 0.5 parts in 109 with

an uncertainty of 1 part in 109

.

! We are collaborating with Gerard

Geneves of LCIE, France. We have

delivered a complete NIST-developed

programmable-voltage standard system,

which they will use as one corner of a

quantum-based metrology triangle experiment comparing resistance, current

and voltage.

Digitally synthesized 2.86 kHz sine wave from a

semiconductor generator showing harmonic

distortion at 47 dB below the fundamental

frequency. High harmonic distortion indicates an

imperfectly synthesized waveform.

Synthesized 2.86 kHz sine wave from a 4,096

junction array. The undesired harmonics are

reduced to 94 dB below the fundamental

frequency because of perfect quantization by the

superconducting Josephson junctions.

! We have begun a collaboration with

Ian Robinson of the National Physical

Laboratory (NPL), England, to provide a

programmable 1 V probe and chip for

their watt balance experiment. NPL will

purchase the probe from NIST and

construct their own bias electronics and

computer control.

! We are collaborating with Mark

Blamire at the University of Cambridge,

England, on the development of

nanoscale junction fabrication techniques for lumped arrays. Superconductive integrated circuits have been

exchanged for fabrication and testing.

Constant voltage steps were demonstrated in arrays of 10 bilayer Nb-PdAu

SNS junctions where the 50 nm long

junctions were defined by focused ionbeam etching.

-120

-100

-80

-60

-40

-20

0

0 5 10 15 20

Power (dBm)

Frequency (kHz)

Semiconductor generator

imperfect sine output

-47 dBc distortion

-120

-100

-80

-60

-40

-20

0

0 5 10 15 20

Power (dBm)

Frequency (kHz)

Josephson array perfectly 

quantized sine output

-94 dBc distortion

The larger voltage

has enabled 10

times lower

uncertainty for

ac-to-ac

comparisons as

compared to

previous

measurements

using lumped

arrays.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 5

! We are collaborating with

researchers at Japan’s Electrotechnical

Laboratory (ETL) to develop cryocooler-compatible Josephson junctions

for programmable voltage standards.

Using NIST designed circuits and

masks, ETL has fabricated uniform

arrays of 4096 NbN-TiN-NbN junctions.

Next year, effort will be focused on

implementing NbN wiring, increasing

the circuit yield, and demonstrating

operation at 10 K.

! We are collaborating with Northrop

Grumman, Inc. on the development of a

pulse-quantized arbitrary waveform

generator for radar applications. This

application uses the same pulsequantized ac synthesis techniques as the

NIST metrology application except the

output signals are at radar frequencies.

We have demonstrated multiple-tone

waveforms at megahertz frequencies and

designed and fabricated SNS junction

circuits using designs from Northrop

Grumman.

Recent Publications

S.P. Benz, P.D. Dresselhaus, and C.J. Burroughs,

“Nanotechnology for next generation Josephson voltage

standards,” Proceedings of the Symposium on

Microtechnology in Metrology and Metrology in

Microsystems, 31 August-1 September 2000, Delft

University of Technology, Delft, The Netherlands, pp. 127-

132.

S.P. Benz, C.J. Burroughs, and P.D. Dresselhaus, “Low

harmonic distortion in a Josephson arbitrary waveform

synthesizer,” Applied Physics Letters Vol. 77, No. 7, pp.

1014-1016 (14 August 2000).

C.A. Hamilton, “Josephson voltage standards- a review,”

2000 Conference on Precision Electromagnetic

Measurements (CPEM) Digest, 14-19 May 2000, Sydney,

Australia, pp. 335-336.

S.P. Benz, L.A. Christian, C.J. Burroughs, and C.A.

Hamilton, “DC voltage synthesis using a pulse-quantized

Josephson voltage source,” 2000 Conference on Precision

Electromagnetic Measurements (CPEM) Digest, 14-19 May

2000, Sydney, Australia, pp. 339-340.

C.J. Burroughs, S.P. Benz, T.E. Harvey, and H. Sasaki, “1

volt Josephson fast reversed DC source,” 2000 Conference

on Precision Electromagnetic Measurements (CPEM) Digest,

14-19 May 2000, Sydney, Australia, pp. 341-342.

B. Jeanneret, A. Rüfenacht and C.J. Burroughs, “Comparison

between the SNS and SIS Josephson voltage standards at

OFMET,” 2000 Conference on Precision Electromagnetic

Measurements (CPEM) Digest, 14-19 May 2000, Sydney,

Australia, pp. 389-390.

R.H. Ono and S.P. Benz, “Optimum characteristics of high

temperature Josephson junctions for “lumped” array

applications,” in Proceedings of the 7th International

Superconductive Electronics Conference (ISEC'99), 21-25

June 1999, Berkeley, pp. 301-303.

S.P. Benz, C.A. Hamilton, and C.J. Burroughs, “Operating

margins for a superconducting voltage waveform

synthesizer,” in Proceedings of the 7th International

Superconductive Electronics Conference (ISEC'99), 21-25

June 1999, Berkeley, pp. 115-117.
Electromagnetic Technology Division 6
Nanoscale

Cryoelectronics

Project Goal

To develop novel integrated circuits

for metrology based on the unique

properties of electronic devices

operating at temperatures below one

kelvin.

Atomic force microscope image of an electron

counter, the heart of a new capacitance standard

based on counting electrons. The standard,

shown in the schematic, consists of the electron

counter, a capacitor, and a single electron

electrometer to monitor the process (not

shown). The electron counter, based on seven

nanometer-scale tunnel junctions in series, can

“pump” electrons onto the capacitor with a error

rate less than 1 electron in 108.

Customer Needs

We work in two principal areas: singleelectron devices and microcalorimeterbased detectors. The goal of the singleelectron project is to use the unique

capabilities of single-electron tunneling

(SET) devices to create new quantum

standards based on the manipulation of

single electrons and to develop measurement techniques applicable to new

generations of electronics that will

operate with very few electrons. The

goal of the microcalorimeter detector

project is to use the unique low-noise,

high-sensitivity properties of cryogenic

electronics to create new generations of

detectors for high energy-resolution

measurements of radiation, from infrared

through X ray, and for mass spectrometry of large molecules.

Single Electron Devices for

Electrical and Photonic

Standards

The U.S. electronics industry continues

to seek improved and more accessible

standards for maintaining instrument

calibration. NIST is working to support

this need through the development of

intrinsic standards based on fundamental

physical principles, such as the volt,

based on the Josephson effect, and the

ohm, based on the quantum Hall effect.

For capacitance, NIST’s primary

standard (the calculable capacitor) is a

unique instrument that is difficult to

replicate, and it currently provides the

best accuracy at only one fixed

frequency.

We are focused on producing a

capacitance standard based on counting

electrons. This standard will provide

accurate calibrations over a wide range

of frequencies and will be more easily

replicated to meet customers’ needs.

This same technology is being explored

as a way to create new optical

calibration devices based on the

production of single photons.

Technical Strategy

The creation of electronic devices

capable of manipulating and detecting

individual electrons has opened the door

to the development of entirely new

standards and metrology tools. SET

devices are made possible by a

combination of state-of-the-art nanolithography to create the nanometer-scale

devices, millikelvin cryogenics to cool

the devices to their operating temperature, custom low-noise electronics to

operate and measure the devices, and

fundamental physics, to understand and

diagnose the operation of the devices.

Maintaining expertise and capabilities

across these fields represents the core

technical strategy of this effort.

Technical Contact:

David A. Rudman

rudman@boulder.nist.gov

We have already

demonstrated a

prototype capacitance

standard based on

counting electrons one

at a time.

 Electromagnetic Technology Division 7
 8

We will continue to develop theoretical

models for the effect of noise on SET devices

and test specific predictions for the

performance of electron pumps in the

presence of such noise.

At present, the main application for SET

devices within the project is to create a

new capacitance standard based on the

fundamental definition of capacitance:

capacitance is stored charge per unit

voltage, C=Q/V. By placing a known

number of electrons on a capacitor, and

measuring the voltage across the

capacitor, C can be determined. A

prototype of such a standard has been

demonstrated with repeatability on order

of 1 part in 107. In order to confirm the

accuracy of the standard, a portable

version must be taken to NIST in

Gaithersburg for direct comparison with

the calculable capacitor.

In collaboration with the Electricity Division,

we will build a new copy of the capacitance

standard in a transportable dilution

refrigerator. We will confirm its operation and

take it to Gaithersburg for comparison

against the calculable capacitor.

With the availability of electron pumps,

it may be possible to perform unique

comparisons of the three intrinsic

electrical standards: the volt (based on

the Josephson junction), the ohm (based

on the quantum Hall effect) and now the

ampere (based on counting electrons).

This test, known as the quantummetrology triangle, will provide new

understanding and confidence in these

quantum standards. The experiments

will require a significant increase in

current from the electron pump.

We will develop a superconducting version of

the electron pump, which will pump much

faster than the conventional version used

thus far for the capacitance standard.

SET devices can also be used as tools to

measure the performance of other

devices that operate with individual

electrons. Under a new NIST-funded

program, work has begun on creating a

new class of electronic devices designed

to produce single photons on demand.

These devices will be based on quantum

dots of semiconductor materials. To

understand their behavior, it will be

necessary to measure the electrical

currents into the dots at the single

electron level. This can be done only

using SET technology.

In collaboration with the Optoelectronics and

Semiconductor Electronics Divisions, we will

integrate SET devices into a single-photon

circuit and confirm the electrical operation of

the photon source.

Accomplishments

! The past few years have brought to

fruition the results of a decade of

research into SET electronics. The goal

of this work has been to develop a

capacitance standard based on counting

electrons. A thorough understanding of

the physics of SET devices has been

necessary to count electrons with metrological accuracy. The fundamental error

mechanisms in the electron pump have

been the subject of theoretical and

experimental investigations in the

project for several years. The development of an experimental technique for

characterizing individual junctions in the

pump made possible the first quantitative comparison between experiment

and theory in the regime of very rare

errors. This comparison showed that the

pump was not performing nearly as well

as the standard theory predicted.

Experiments and theoretical work on the

effect of photon-assisted tunneling,

which is not included in the standard

theory, have shown that this is probably

the origin of the discrepancy. The likely

source of the photons is fluctuating

background charges in the substrate or in

the pump itself, which produces 1/f

noise even at the very high frequencies

(GHz) needed to affect pump

performance.

! A prototype of a capacitance

standard based on counting electrons has

now been demonstrated. The components of the standard are an electron

counter, a capacitor, and an electrometer

to monitor the process. The electron

counter is based on seven nanometerscale tunnel junctions in series. It can

“pump” electrons onto the capacitor with

an error rate less than one electron in

108

. The electron pumping is monitored

with an SET – based electrometer

To evaluate the

electron counting

capacitance

standard, we will

compare it with the

present calculable

capacitor.

Work has begun on

creating a new class

of electronic

devices designed to

produce single

photons on

demand.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 9

fabricated on the same chip as the pump,

with a charge sensitivity better than 10–2

electrons. The capacitor, fabricated by

Neil Zimmerman in the Electricity

Division, operates at cryogenic

temperatures and uses vacuum as the

dielectric, resulting in a frequencyindependent capacitance.

Demonstration of pumping electrons on and off

a prototype capacitance standard.

To operate the standard, approximately

100 million electrons are placed, one at a

time, on the capacitor. The voltage

across the capacitor is then measured,

resulting in a calibration of the cryogenic

capacitor. This capacitance can then be

transferred to room temperature using a

standard ac bridge measurement technique. The figure above shows the result

of pumping electrons on and off the

capacitor, with a 20 second pause when

fully charged to measure the voltage

(shown in expanded view above). The

result is a value of capacitance with a

repeatability of one part in 107.

! The past year has produced

significant progress towards the

development of a single-photon turnstile,

a device designed to generate single

photons on demand using quantum dots

(QD) and single-electron principles. The

first step towards this end requires the

development of a process to allow

electrical contact to individual quantum

dots. The process uses a combination of

photolithography, electron-beam lithography, atomic-force microscopy, etching, and film deposition to allow individual QD, which are only a few tens of

nanometers in diameter, to be located

and connected to macroscopic leads on

the same chip. Each of the 12 steps in

the process has been executed

individually with good yield, and

fabrication of a completed chip with

contact to four separate quantum dots

will be pursued next. An AFM image of

electron-beam lithographically-written

contacts to a single quantum dot is

shown below.

An AFM image of electron-beam lithographicallywritten contact to a single QD. The black triangle

indicates where the QD is located. The lead that

approaches the QD from the bottom is used to

capacitively couple the QD to a single-electron

transistor structure. The white lines coming in

from the left side of the micrograph are

alignment marks.

Cryogenic Detectors

The ability to detect photons with high

energy resolution and near-unity

quantum efficiency will enable new

generations of spectroscopic tools to be

created. Improved energy-dispersive Xray spectroscopy will be used to solve a

wide range of problems in materials

analysis. For example, the semiconductor manufacturing industry needs

improved X-ray materials analysis to

identify small contaminant particles on

wafers.

To make this technology available to the

materials analysis community, NIST has

licensed several patents to two U.S.

companies for commercialization. Additionally, NIST’s Chemical Science and

Technology Laboratory will use this

spectroscopy to improve its own

materials-analysis capability. The

National Aeronautics and Space

Administration (NASA) also needs

improved instruments for imaging at

wavelengths from infrared to X-ray. We

Our detectors will

help the

semiconductor

industry to

improve yield by

identifying small

contaminant

particles.
 10

are working with NASA to bring this

technology into use.

The same devices can also be used, in

principle, to greatly enhance mass

spectrometry of high-mass biomolecules

such as DNA that will be of great

importance to the biotechnology

community.

Technical Strategy

Introducing a radically new technology

such as cryogenic microcalorimeters to a

large community requires creating and

demonstrating an entire measurement

instrument, not just the detector. In this

case, we have developed superconducting electronics to read the detectors,

compact adiabatic demagnetization

refrigerators to simplify cooling the

detectors to millikelvin operating

temperatures, and room-temperature

electronics to process the output signals.

The resulting system makes a much

more compelling case for the technology

than the performance specifications of

the detector alone. Thus, our goal is to

develop new detector systems and to

apply those systems to problems of

interest to our customers.

In the area of X-ray spectroscopy, the

performance target depends on the

application. For materials analysis,

further improvements in energy resolution are not as important as an increase

in the maximum count rate and collection area. This can be achieved by the

creation of multipixel arrays of

detectors. In addition to the fabrication

difficulties in making such arrays, the

cold- and room-temperature electronics

to read out the arrays must also be

created. The current approach to the

electronics is to develop a superconducting quantum interference device

(SQUID) multiplexer (MUX) circuit to

read the array, and room-temperature

digital signal processing (DSP) to

process the MUX signals.

We will develop a small array of

microcalorimeter detectors for X-ray analysis

and read them out using SQUID MUX and

DSP circuitry.

The application of X-ray detectors to

materials-analysis problems represents a

test bed for this technology. With a focus

towards the semiconductor manufacturing industry, problems in characterization of small particles and very thin

layers of material are very important.

The ability of the detector to differentiate overlapping X-ray lines at low

energies enables analysis of previously

inaccessible systems.

In collaboration with the Chemical Science

and Technology Laboratory, we will install

the microcalorimeter spectrometer on stateof-the-art microanalysis tools at NISTGaithersburg to further demonstrate the

capabilities of the system for analysis of

particles and thin films.

For some materials-analysis applications

and for astronomical observations, improvements in the energy resolution at

relatively high X-ray energies (6000 eV)

are still needed. In addition, largeformat, densely packed arrays of

detectors are required for imaging. These

are ambitious goals that will require

improved understanding of the

limitations on performance of

microcalorimeter detectors. Novel fabrication techniques will need to be

developed to make densely packed

arrays, and SQUID MUX and DSP

circuitry will be required to read out the

arrays.

We will develop models of single-pixel

microcalorimeter performance to assist in

improving detector sensitivity, and will

fabricate and test novel detector designs

based on these models.

We will develop small, densely packed arrays

of detectors and instrument them with

appropriate read out electronics.

These detectors also provide remarkable

performance at lower energies, from

infrared through visible. Here the goal is

clearly to develop large-format imaging

arrays with high sensitivity and energy

resolution. The present application for

these arrays is in astronomy, both

ground-based and in space.

We will develop arrays of microcalorimeter

detectors optimized for infrared astronomy

along with the necessary wiring, SQUID MUX

The ability of the

microcalorimeter

detector to differentiate

overlapping X-ray

lines enables

analysis of

previously

inaccessible

systems.

Introducing a

radically new

technology such

as cryogenic

microcalorimeters

to a large

community

requires creating

and

demonstrating an

entire

measurement

instrument, not

just the detector.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 11

and room-temperature DSP electronics to

read the array.

The development of digital signalprocessing electronics for the detector

project stimulated interest in applying

this technology to other metrology

problems. Electronic thermometers

based on Johnson noise have been

limited by electronic measurement

capabilities. In collaboration with other

members of the Division and the

Chemical Science and Technology

Laboratory, we have been awarded a

NIST grant to develop Johnson noise

thermometers using state-of-the-art

analog and digital electronics. The key

innovation will be the creation and use

of a Josephson-junction-based calculable

noise voltage source to provide accurate

calibration of the amplifiers and correlators needed to make the

thermometer.

We will develop the analog and digital

electronics needed to realize a new

generation of Johnson noise thermometers.

Accomplishments

! The success of the microcalorimeter

detector project has been made possible

by broad expertise within the Division in

such fields as physics of superconductivity, device fabrication including Si micromachining, superconducting

electronics, cryogenic engineering, and

low-noise, room-temperature electronics.

Without expertise in all of these areas,

the complete systems that have provided

the compelling demonstrations for the

power of this technology would not have

been possible. As an example, the

schematic on the above right shows a

micro-calorimeter energy-dispersive

spectrometer (EDS) X-ray detector

system inserted into a scanning electron

microscope to allow chemical microanalysis of materials.

Schematic of a microcalorimeter energydispersive spectrometer (EDS) X-ray detector

system inserted into a scanning electron

microscope.

! The microcalorimeter detector uses a

superconducting/normal-metal bilayer to

create a superconducting transition-edge

sensor (TES). Using the proximity

effect, the transition temperature of the

bilayer can be selected to match each

specific application. We created an

accurate model of the proximity effect in

this system, which allows the thickness

for each layer to be calculated, minimizing trial-and-error fabrication.

! Originally each TES was individually fabricated using Al/Ag bilayers

and a shadow-mask deposition process,

but recent advances with Mo/Cu bilayers

have allowed whole-wafer photolithographic processing, dramatically

improving yield. The TES and

appropriate X-ray absorber are fabricated on a Si3N4 micromachined

membrane to produce the required

thermal isolation. The device operates

using a current bias and extreme

negative electrothermal feedback, so that

it self-regulates in temperature.

Absorbed X rays produce heat pulses in

the device, which are read out as pulses

of reduced bias current by a first-stage,

single-SQUID amplifier located adjacent

to the detector to minimize inductance.

The output of the first-stage SQUID is

read out by a unique 100-SQUID

amplifier invented and fabricated by the

Division specifically to allow direct

coupling of the signal to roomtemperature electronics. The detector is

cooled to below 100 mK by a compact

The key innovation

for absolute noise

thermometers is a

Josephson-junction

calculable noise

voltage source.

The success of the

microcalorimeter

detector project has

been made possible

by the broad

expertise within the

division in such

fields as physics of

superconductivity,

device fabrication

including Silicon

micromachining,

superconducting

electronics,

cryogenic

engineering, and

low noise, roomtemperature

electronics.
 12

adiabatic demagnetization refrigerator,

which has unique design features that

produce nearly 24 hours of continuous

operation, and days of hold time for

liquid helium.

Comparison of resolutions of NIST microcalorimeter EDS to standard semiconductor EDS.

This system holds the world record for

energy resolution for an EDS detector of

2.0 eV at 1500 eV, which is over 30

times better than the best high-resolution

semiconductor-based detectors currently

available. The figure above compares an

X-ray spectrum obtained with this

system to that from a semiconductor

energy-dispersive detector, clearly demonstrating the remarkable improvement in resolution. The specimen was a

glass prepared by Dale Newbury of the

Chemical Science and Technology

Laboratory to use as a test standard for

EDS. We have used the system to

identify submicrometer particles of

materials such as W on Si substrates, an

identification problem that is impossible

with standard EDS detectors and of great

importance to the semiconductor

industry. It has also demonstrated energy

shifts in the EDS X-ray spectra of

materials such as Al, Fe, and Ti,

depending on their chemical bonding

state, thus allowing differentiation

between a particle of Al and Al2O3

, for

example.

Furthermore, we have completed several

effective partnerships with companies in

the semiconductor industry to demonstrate the usefulness of the microcalorimeter spectrometer for practical

analysis. For example, in collaboration

with researchers at Lucent Technologies

in Orlando, Florida, we critically compared the trace Cu detection ability of

microcalorimeter-based x-ray analysis

with that of other industrial analytical

techniques, including conventional

semiconductor Energy-Dispersive Spectrometry, Auger Electron Spectrometry,

and Secondary Ion Mass Spectrometry

(SIMS). Although only SIMS is capable

of trace Cu analysis down to the ~0.02

% atomic level, microcalorimeter EDS

fared very well in comparison with the

other non-destructive analytical

techniques.

A microcalorimeter EDS spectrum of 0.7 % by

weight Cu/Al alloy thin film (from Lucent

Technologies) demonstrating the sensitivity of

microcalorimeter EDS for trace Cu analysis in the

semiconductor industry.

Based on these types of results, two U.S.

X-ray spectrometer companies have

acquired licenses for a suite of patents

covering this technology to begin

commercialization. Technology transfer

to both companies has occurred, and

both are planning to have an initial

system available soon.

! To enable more advanced applications of this technology to materialsanalysis problems requires coupling the

spectrometer to state-of-the-art analytical tools, such as are available in the

Chemical Science and Technology

Laboratory at NIST-Gaithersburg. To

this end, the single-pixel spectrometer

used in the above research has been

relocated to Gaithersburg. Installation

and qualification is nearly complete, and

the system will be used jointly with

CSTL to continue microanalytical work

on problems of interest to the semiconductor and other materials-intensive

industries.

500 1000 1500 2000

0

500

1000

1500

2000

2500

0

50

100

850 900 950 1000

C-K Cu-L

O-K W-M

W-M

W-M

Si-K

Counts (0.16 eV/channel)

Energy (eV)

Cu Lβ1

NIST μcal EDS

3 keV beam energy

1.3 nA beam current

500 s-1 input rate

1000 s live time

Cu Lα1,2

Our compact

adiabatic

demagnetization

refrigerator has

unique design

features that

produce nearly 24

hours of continuous

operation, and days

of hold time for

liquid helium.

This system holds

the world’s record

for energy

resolution for an

EDS detector.

The system has

demonstrated for

the first time EDS

energy shifts

depending on

chemical bonding

state.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 13

A photograph of an 8-channel SQUID multiplexer

chip fabricated at NIST. On the 6.4 mm chip are

8 first-stage SQUID amplifiers and one secondstage series-array SQUID amplifier. This chip has

been used to multiplex 8 channels at 1 million

samples per second.

! In addition to X-ray detection, this

microcalorimeter technology is being

developed for use at other wavelengths,

from optical down through the submillimeter. Our TES bolometers have

achieved world-record sensitivity for

infrared radiation. This impressive result

confirms the utility of this technology

for this application as well. However, to

meet the needs of NASA, large-format

arrays of these detectors have to be

fabricated, and electronics have to be

created to read out the arrays. We have

developed the first SQUID-based MUX

for this purpose, and have demonstrated

it with a 1 × 16 array of TES bolometers.

This array and MUX have been

delivered to NASA, which intends to

install it in the spring of 2001 on the Cal

Tech Submillimeter Observatory located

in Hawaii.

! The ability to handle the data read

out from large arrays of detectors may,

in the end, prove as important as the

performance of the detectors themselves.

Even once a multiplexing technology is

developed, the huge amount of data

acquired from this system will require

new room-temperature electronics to

collect and process the information. We

developed a first-generation DSP system

and have successfully interfaced it with

the SQUID amplifiers, providing the

feedback required for their operation. In

collaboration with Stanford University,

these electronics have been used with a

small array (2 x 2) of optical TES

detectors (built by Stanford) to perform

astronomical observations at the

McDonald Observatory. Using the electronics, real-time data were acquired

from the Crab pulsar at higher rates than

had been previously achieved.

! This detector technology is also

being explored as a means of providing

new capabilities in the field of mass

spectrometry. The microcalorimeter can

detect the kinetic energy associated with

the impact of an accelerated ion on the

detector. We have recently demonstrated the use of this energy measurement to determine the charge of incident

ions created using an electro-spray ion

source (ESI). ESI is widely used for

mass spectrometry of biomolecules

because it creates gas-phase ions directly

from liquid input. One important drawback of ESI is that it creates ions with a

wide range of charge states, leading to

many peaks in the measured spectrum of

mass-to-charge ratio. This difficulty

limits the utility of ESI for complicated

samples such as mixtures. The use of an

energy-resolving detector may provide a

solution to this difficulty by allowing an

independent measurement of the ionic

charge, which can then be used to

deconvolve the spectra. We have

demonstrated this technique with a

variety of proteins (masses up to 77

kDa), and use this technique to analyze a

mixture of calibration proteins. While

this technique shows promise, the

impact-energy resolution is currently

insufficient for widespread application.

We are exploring the factors limiting the

energy resolution.

Recognition

! Presidential Early Career Award for

Scientists and Engineers to Mark Keller,

2000.

! NIST Condon Award, for excellence

in writing, 2000.

Patents

! "Particle Calorimeter with Normal

Metal Base Layer," issued June, 1997.

The ability to handle

the data read out from

large arrays of

detectors may, in the

end, prove as important

as the performance of

the detectors

themselves.

This detector

technology may provide

new capabilities in

mass spectrometry.
 14

! "Mechanical Support for a Two Pill

Adiabatic Demagnetization Refrigerator," issued August 1999.

! "Superconducting Transition-Edge

Sensor," issued March 1999.

! "Microcalorimeter X-ray Detectors

with X-ray Lens," issued March 1999.

! "Superconducting Transition-Edge

Sensor with Weak Links," filed

November 1998.

! "The Use of SuperconductorInsulator-Normal (SIN) Tunnel Junctions in Superconducting Quantum

Interference Device (SQUID) Multiplexers," disclosure submitted, April

2000.

Recent Publications

Eichenberger, A.L.; Keller, M.W.; Martinis, J.M.;

Zimmerman, N.M., "Measurement of the Frequency

Dependence of a Single-Electron Tunneling Capacitance

Standard", Proc., Conf. on Precision Electromag. Meas.

(CPEM) 2000, 16-17 (2000).

Keller, M.W.; Zimmerman, N.M.; Eichenberger, A.L.;

Martinis, J.M., "A Capacitance Standard Based on Counting

Electrons", Proc. Conf. on Precision Electromag. Meas.

(CPEM) 2000, 317-318 (2000).

Abusadi, R.; Akerib, D.S.; Barnes Jr., P.D.; Bauer, D.A.;

Bolozdynya, A.; Brink, P.L.; Bunker, R.; Cabrera,

B.;Caldwell, D.O.; Castle, J.P.; Clarke, R.M.; Colling, P.;

Crisler, M.B.; Cummings, A.; Da Silva, A.; Davies, A.K.;

Dixon,R.; Dougherty, B.L.; Driscoll, D.; Eichblatt, S.; Emes,

J.; Gaitskell, R.J.; Golwala, S.R.; Hale, D.; Haller,

E.E.;Hellmig, J.; Huber, M.E.; Irwin, K.D.; Jochum, J.;

Lipschultz, F.P.; Lu, A.; Mandic, V.; Martinis, J.M.; Nam,

S.W.;Nelson, H.; Neuhauser, B.; Penn, M.J.; Perera, T.A.;

Perillo Isaac, M.C.; Pritychenko, B.; Ross, R.R.; Saab,

T.;Sadoulet, B.; Schnee, R.W.; Seitz, D.N.; Shestople, P.;

Shutt, T.; Smith, A.; Smith, G.W.; Sonnenschein,

A.H.;Spadafora, A.L.; Stockwell, W.; Taylor, J.D.; White, S.;

Yellin, S.; Young, B.A., "Exclusion Limits on the WIMPNucleon Cross Section from the Cryogenic Dark Matter

Search", Phys. Rev. Lett. 84, 5699-5701 (2000).

Wollman, D.A.; Nam, S.W.; Hilton, G.C.; Irwin, K.D.;

Bergren, N.F.; Rudman, D.A.; Martinis, J.M.; Newbury,D.E.,

"Microcalorimeter Energy-Dispersive Spectrometry Using a

Low Voltage Scanning Electron Microscope", J. Microscopy

199, 37-44 (2000).

Nam, S.; Wollman, D.A.; Hilton, G.C.; Chervenak, J.;

Deiker, S.; Irwin, K.D.; Martinis, J.M., "A Digital Readout

Scheme for Arrays of Microcalorimeter X-ray Detectors",

Proc. Microscopy and Microanal. 2000, 742-743 (2000).

Wollman, D.A.; Newbury, D.E.; Nam. S.W.; Hilton, G.C.;

Irwin, K.D.; Rudman, D.A.; Deiker, S.; Bergren,

N.F.;Martinis, J.M., "Microcalorimeter EDS: Benefits and

Drawbacks", Proc. Microscopy and Microanal. 2000, 738-

739 (2000).

Wollman, D. A., Newbury, D. E., Nam, S. W., Hilton, G. C.,

Irwin, K. D., Rudman, D. A., Deiker, S., Bergren, N. F., and

Martinis, J. M., "Microcalorimeter EDS for low voltage

microanalysis", Proc. of the 2nd Conf. Int. Union Microbeam

Analysis Societies, pp. 125-126 (2000).

Newbury, D. E., Wollman, D. A., Hilton, G. C., Irwin, K. D.,

Bergren, N. F., Rudman, D. A., and Martinis, J. M., "The

approaching revolution in X-ray microanalysis: The

microcalorimeter energy dispersive spectrometer", Journal of

Radioanalytical and Nuclear Chemistry, 244, 627 (2000).

J.A. Chervenak, E.N. Grossman, K.D. Irwin, J.M. Martinis,

C.D. Reintsema, C.A. Allen, D.I. Bergman, S.H. Moseley, R.

Shafer, "Performance of multiplexed SQUID readout for

Cryogenic Sensor Arrays", Nuclear Instruments and Methods

in Physics Research A 444, 107 (2000).

J.M. Martinis, G.C. Hilton, K.D. Irwin, and D.A. Wollman,

D. A., "Calculation of Tc in a normal-superconductor bilayer

using the microscopic-based Usadel theory", Nuclear

Instruments and Methods in Physics Research A 444, 23

(2000).

D.A. Wollman, S.W. Nam, D.E Newbury, G.C. Hilton, K.D.

Irwin, N.F. Bergren, S. Deiker, D.A. Rudman, and J.M.

Martinis, "Superconducting transition-edge-microcalorimeter

x-ray spectrometer with 2eV energy resolution at 1.5 keV",

Nuclear Instruments and Methods in Physics Research A

444, 145 (2000).

K.D. Irwin, G.C. Hilton, J.M. Martinis, S. Deiker, N.F.

Bergren, S.W. Nam, D.A. Rudman, and D.A. Wollman, "A

Mo-Cu superconducting transition-edge microcalorimeter

with 4.5 eV energy resolution at 6 keV", Nuclear Instruments

and Methods in Physics Research A 444, 184 (2000).

R. L. Kautz, M. W. Keller, and J. M. Martinis, "Noiseinduced leakage and counting errors in the electron pump",

Phys. Rev. B (accepted for publication).

A. L. Eichenberger, M. W. Keller, J. M. Martinis, and N. M.

Zimmerman, "Frequency Dependence of a Cryogenic

Capacitor Measured Using Single-electron Tunneling

Devices," J. Low Temp. Phys., 118, 317 (2000).

M. Covington, M. W. Keller, R. L. Kautz, and J. M. Martinis,

"Photon-assisted Tunneling in Electron Pumps," Phys. Rev.

Lett. 84, 5192 (2000).

J. A. Chervenak, K. D. Irwin, E. N. Grossman, J. M.

Martinis, C. D. Reintsema, M. E. Huber, "Superconducting

Multiplexer for Arrays of Transition Edge Sensors," Appl.

Phys. Lett. 74, 4043 (1999).

C. K. Stahle, D. McCammon, K. D. Irwin, "Quantum

Calorimetry," Physics Today 52, 32 (1999).

R. L. Kautz., M. W. Keller, and J. M. Martinis, "Leakage and

Counting Errors in a Seven-Junction Electron Pump," Phys.

Rev. B 60, 8199 (1999).

M. W. Keller, A. L. Eichenberger, J. M. Martinis, and N. M.

Zimmerman, "A Capacitance Standard Based on Counting

Electrons," Science, 285, 1706 (1999).

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 15

High Performance Sensors, Infrared

Detectors, and Mixers

Project Goal

To develop and apply cryogenic

electronic technology in the millimeter

wave to infrared (IR) spectral range

measurements and standards in

support of other NIST Divisions and

U.S. industry.

A 1 × 8 array of 300 mK bolometers.

Customer Needs

The U.S. aerospace and defense

industries are being pushed toward both

higher performance and faster, less

expensive systems. Devices originally

developed for cryogenic electronics, in

particular cryogenic bolometers and

tunnel diodes, are often useful in a wide

variety of metrological applications, as

well as in other scientific or commercial

applications not always at cryogenic

temperatures. Atmospheric scientists use

satellite-based spectrometers to monitor

the worldwide distribution of species

relevant to climate change. Security

equipment manufacturers are developing

millimeter wave imagers for concealed

weapons detection. Submillimeter

spectroscopy is being developed as a

diagnostic tool, monitoring species

concentrations and temperatures, for

plasma processes in semiconductor

manufacturing. The activities of this

project focus on adapting millimeter

wave to infrared technology for the

benefit of these industries, either directly

through collaborative research and

development programs, or indirectly by

improving the metrological capabilities

of other NIST Divisions, which in turn

make the results available to U.S.

industry.

Technical Strategy

The work of this project focuses

particularly on two types of devices,

bolometers and tunnel junctions. These

devices were initially developed for

cryogenic electronic applications, but are

also useful in the detection or frequency

conversion of radiation from millimeter

to infrared wavelengths. Our efforts to

improve the sensitivity or precision of

radiation power measurements exploits

the low noise properties of thin film

bolometers. Our work on improving the

frequency coverage and efficiency of

frequency conversion (i.e., rectification

and mixing) exploits the low capacitance

and nonlinear transport properties of

tunnel diodes.

We work on the development of

bolometers with ever-higher sensitivity,

and their incorporation into imaging

systems based on large focal-plane

arrays. Depending on engineering tradeoffs we make during the design phase

(i.e. between sensitivity and other

characteristics such as operating temperature), these imagers are applicable to

remote sensing of the Earth, atmospheric

spectroscopy, or astronomy. Some of

this work is supported by the National

Aeronautics and Space Administration

(NASA) and its contractors in the

aerospace industry.

We will develop a high sensitivity bolometer

for far-IR wavelengths with an NEP of less

than 10–18 W/√Hz.

We will develop a 32 × 32 element

bolometer array with NEP less than 5 × 10–17

W/√Hz.

Because readout is a critical element in

any array technology, a superconducting

quantum interference device (SQUID)-

based cryogenic multiplexer is being

developed to provide the front-end

processing of the bolometer outputs. The

bolometers are superconducting films

Our large arrays of

bolometers are

applicable to remote

sensing of the earth,

atmospheric

spectroscopy, and (by

NASA) astronomy.

Technical contact:

Erich N. Grossman

grossman@boulder.nist.gov
 16

biased on their transition edge, and

operated in an electrical-substitution

mode.

Monolithic SQUID multiplexer circuit. A 1 × 8

prototype has been demonstrated at pixel rates

of 1 MHz.

Far-infrared spectroscopy at the highest

levels of sensitivity and spectral resolution has traditionally been accomplished with heterodyne techniques, in

which the weak signal to be measured is

combined with a strong “local oscillator” and focused onto a detector or “mixer”.

The signal at the difference frequency is

then measured with an ultra-low-noise

detection system. We have recently

begun a program to develop ultrasensitive mixer elements based on

superconducting hot-electron bolometers. Like the transition-edge bolometer arrays, a major application for

these mixers lies in space-based remote

sensing. Hot-electron bolometers formed

of thin films of niobium and niobium

nitride have already demonstrated sensitivities within a factor of five of the

fundamental quantum limit. The focus of

our research in this area, and of the most

recent progress in the state of the art, lies

in extending the frequency coverage of

this measurement technique to above 2

THz, and in developing integrated arrays

of heterodyne mixers.

By 2001, we will demonstrate a 2 x 2

element hetrodyne mixer array operating at

2.5 THz, with noise tempertaure within a

factor of 10 of the quantum limit.

We also use superconducting bolometers

for standards-related metrology, both for

audio frequencies (where they are

known as ac-dc thermal transfer

standards) and for IR frequencies (where

they are known as electrical substitution

radiometers). This project is collaborative with the Electricity Division,

which is responsible for ac electrical

calibration and metrology.

For audio frequencies, we will achieve

precision better than one part in 106 in ac

voltage transfer at microwatt power levels.

We apply tunnel junctions, originally

developed for cryogenic electronics, to

IR rectification and mixing applications.

For decades, scientists have envisioned

highly efficient generation of solar

power by the direct rectification of

sunlight in ultra-low-capacitance diodes.

Recent advances in nanoscale fabrication

make such visions much more realistic;

commercial firms and government

agencies are now working with NIST to

realize them using the nonlinearity of

tunneling in uncooled, metal-insulatormetal (MIM) thin-film diodes.

Our goal is to observe photon-assisted

tunneling steps in uncooled MIM diodes at 30

THz. By 2001, we aim for operation at above

100 THz with ac to dc conversion efficiency

from greater than 20 %.

Direct conversion of solar energy concept

showing array of antenna-coupled metalinsulator-metal diode rectifiers on flexible panel.

Separately, IR frequency synthesis and

metrology have traditionally been

performed by harmonic mixing of the

output of low-frequency standards in

whisker-contacted tunnel diodes, and the

Recent advances in

nanoscale

fabrication make

the vision of direct

rectification of

sunlight much more

realistic.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 17

same thin film MIM diodes we are

developing will enable the creation of

frequency-synthesis systems that are

much more compact, reliable, and user

friendly.

We also develop thin-film bolometers,

coupled to antennas and operated at

room temperature, for use in applications

where the very highest sensitivity is not

required. An example is millimeter wave

imaging for the detection of concealed

weapons (clothing is transparent to

radiation at millimeter wavelengths). In

collaboration with the Electricity

Division and the Office of Law

Enforcement Standards, we are

developing an actively illuminated

imaging system for this application,

based on a full wafer-scale array of

several hundred antenna-coupled

bolometers.

We will develop an imaging system capable

of detecting a reflectivity contrast less than

0.5 % at 5 meters range using a 16 x 16

element array.

Nanoscale metal-insulator-metal diode, 40 nm ×

40 nm, integrated with a dipole antenna.

In most of these programs, the lithographic antenna forms an important

component of the system, and frequently

requires as much development as the

bolometer or tunnel diode, although its

only function is the efficient coupling of

radiation to the device. We therefore

perform significant development work

on lithographic antennas themselves.

These are ubiquitous at lower,

microwave frequencies in wireless

telecommunications systems such as

cellular phones. Moreover, the

polarization-specific nature of antennas

can frequently be exploited to provide

our devices with additional functionality.

For example, the emittance/reflectance

properties of a surface differ for s and p

polarizations of obliquely incident

radiation. This can be exploited to

resolve the ambiguity inherent in

noncontact thermometry or materials

analysis due to unknown specimen

emissivity. In collaboration with a

commercial semiconductor metrology

manufacturer, we are exploring the

potential of this technique.

Accomplishments

! First Electrical Substitution Radiometer Based on Superconducting

Sensors —We completed a standardsgrade, electrical substitution radiometer

for measurement of mid- and far-IR

wavelength blackbody radiation, and

delivered it to Division 844, which is

responsible for optical and IR power

calibration and metrology. For an

extended series of experiments covering

a range of substitution power from 500

pW to 5 μW, the instrument’s noise floor

could be approximated as 4 pW plus 7 ×

10−6 times the measured power. We are

now helping a U.S. manufacturer of

cryogenic radiometers incorporate

superconducting sensors into its

products.

! First ac-dc Thermal Transfer

Standard Based on Superconducting

Sensors —We completed and reported a

set of preliminary experiments on ac-todc transfer using similar transition-edge

bolometers. These yielded errors varying

from 50 to 150 × 10–6 W (for frequencies

from 100 Hz to 10 kHz), limited chiefly

by inaccuracy introduced in delivering

the ac signal to the cryogenic reference

plane.

! First SQUID-Based Multiplexer for

Transition-Edge Bolometers — In

applications to far-IR astronomy (both

imaging and low-resolution spectroscopy), speed, and therefore sensitivity, are limited by the number of

pixels that can be read simultaneously.

Present cryogenic far-IR bolometer

arrays are already at the practical limit

for the number of wires connecting the

arrays to room temperature, so further

improvement requires cold multiplexing.

Over the last two years, a novel SQUIDOur millimeter wave

imaging is being

evaluated for

concealed weapons

detection.

We are helping a U.S.

manufacturer of

cryogenic radiometers incorporate

superconducting

sensors into its

products.
 18

based multiplexing scheme was

conceived and demonstrated in a 1 × 8

channel prototype. It operates at pixel

rates up to 1 MHz, and has sufficiently

low noise to multiplex up to about 250

channels without degrading the system

noise.

! First Monolithic Arrays of

Transition-Edge Bolometers for Space

Astronomy — These 1 × 8 arrays are

prototypes of a new generation of

detector arrays for low-background, farinfrared astronomy, and were spotlighted

in a recent article in Superconductor and

Cryoelectronics magazine. The Al-Ag or

Mo-Au arrays are fabricated on

micromachined Si structures that enable

construction of closely packed twodimensional arrays. The bolometers

operate with a 300 mK base temperature,

requiring 3He refrigeration, and have a

saturation power of about 5 pW and a

time constant of about 2 milliseconds.

Electrical NEP is phonon-noise limited

at roughly 2 × 10–17 W/•Hz, the best ever

reported for an IR bolometer operating

with 3He refrigeration, and within a

factor of 6 of the best reported for any

other IR bolometer.

! Uncooled Antenna-Coupled MetalInsulator-Metal (MIM) Junctions for IR

Rectification and Mixing — The ultralow capacitance, fully lithographic

diodes have areas as low as 30 × 30 nm2

and are fabricated by angled evaporation

through a free-standing PMMA resist

bridge defined by electron beam

lithography. The diodes are coupled to

planar dipole antennas designed for

resonance at 10 μm wavelength. We

have successfully fabricated and tested

diodes from Al-AlOx-Al, Al-AlOx-Pd,

and Nb-NbOx-Ag materials. The

nonlinear current-voltage characteristics

are accurately predicted by the

Brinkman-Dynes-Rowell theory of tunneling through trapezoidal barriers, both

for the nano-MIMs and for separate,

micrometer sized Nb-NbOx-Ag MIM

diodes. The optical response of the nanoMIM diodes to 10 μm CO2 laser

radiation was clearly proven to arise

from classical rectification. Previous

attempts to develop fully lithographic

MIM diodes, on the other hand, all

foundered on the difficulty of separating

optical signals due to rectification from

those due to thermal mechanisms. The

nonlinearity observed in the large-area

diodes is, according to theory, sufficient

to enable observation of photon-assisted

tunneling steps, a phenomenon observed

at room temperature only recently in

GaAs heterostructures.

Recent Publications

M. E. MacDonald, A. Alexanian, R. A. York, Z. Popovic,

and E. N. Grossman, “Spectral transmittance of Lossy

Printed Resonant-Grid Terahertz Bandpass Filters,” IEEE

Trans. Micro. Theory Tech., in press.

J. A. Chervenak, K. D. Irwin, E. N. Grossman, K. D. Irwin, J.

M. Martinis, C. D. Reintsema, C. A. Allen, D. Bergman, S.

H. Moseley, and R. Shafer, “Performance of Multiplexed

SQUID Readout for Cryogenic Sensor Arrays,” Nuclear Inst.

Methods A, in press.

S. Nolen, J. A. Koch, N. Paulter, C. D. Reintsema, and E. N.

Grossman, “Antenna-Coupled Niobium Bolometers for mmWave Imaging Arrays,” Proc. SPIE, in press.

J. A. Chervenak, K. D. Irwin, E. N. Grossman, J. M.

Martinis, C. D. Reintsema, and M. E. Huber,

“Superconducting Multiplexer for Arrays of Transition Edge

Sensors,” Appl. Phys. Lett. 74, 4043-4045 (June 1999).

C. D. Reintsema, E. N. Grossman, J. A. Koch, “Improved

VO2 Microbolometers for Infrared Imaging: Operation on the

Semiconducting-Metallic Phase Transition with Negative

Electrothermal Feedback,” Proc. SPIE 3698, 190-200 (April

1999).

Our 300 mK infrared

bolometers have the

best noise equivalent

power ever reported.

Our nano-MIM diodes

have clearly rectified

10 μm infrared

radiation.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 19

High Tc

Electronics

Project Goal

To aid and accelerate the

development of new thin-film

materials and devices for electronic

applications, especially high

temperature superconductors (HTS),

thin film oxides, and

microelectromechanical systems

(MEMS).

Pulsed laser deposition chamber for oriented

growth of complex oxides.

Customer Needs

We support the emerging HTS

superconducting electronics industry

through measurements, which enable the

development of HTS devices and

circuits. Our customers are also those

other NIST Divisions responsible for

standards and measurement techniques

in areas such as voltage; infrared,

millimeter wave, and microwave

radiation; and time and frequency

standards. In addition, we support other

government agencies, including the

National Aeronautic and Space

Administration (NASA), the Office of

Naval Research (ONR), the National

Security Agency (NSA), and the

Defense Advanced Research Projects

Agency (DARPA).

Technical Strategy

We consider three criteria when

selecting research projects: importance

for standards improvement and

development; importance but precompetitive in the commercial sector;

and the inclusion of a strong component

of innovative science and technology.

To address these criteria, we have

developed fabrication processes, testing

capabilities, and theoretical competence

for HTS devices in the areas of

microwave, millimeter wave and

terahertz metrology and technology;

high-sensitivity bolo-meters; and

Josephson junctions. We use pulsed laser

deposition to grow novel thin-film

materials and take those materials

through processing to final test. We also

collaborate with U.S. and international

standards laboratories that provide

materials and make comparative

measurements. Below we describe the

efforts in the three major thrusts of our

project: microwave measurements and

devices, bolometers and Josephson

junctions, and novel micro- and nanoscale structures.

Microwave measurements and devices

We work with the HTS communication

industry to measure and improve the

capabilities of HTS devices. The rapidly

expanding wireless communications

industry has begun to adopt HTS

components in receiver front-ends. This

effort is driven by the need for more

efficient use of a limited spectrum in the

face of an increasing amount of

interference and signal from other

providers. The introduction of third and

fourth generation technology for the

wireless Internet has created a new

market for improved passive and active

devices. Our work is aimed at addressing

some of the unresolved issues in HTS

devices that impact their ultimate

performance.

We collaborate with the RadioFrequency Technology Division to

improve microwave measurement and

characterization techniques for HTS

films and devices. We are participating

in developing a new standard for

measuring the surface resistance RS. This

Technical Contact:

Ronald H. Ono

ono@boulder.nist.gov

The rapidly expanding

wireless

communications

industry has begun to

adopt HTS components

in receiver front-ends.

We have implemented

a cryogenic microwave

probe station for

broadband (dc-40

GHz) characterization

of temperature

dependent microwave

properties.
 20

is under the auspices of the International

Electrotechnical Commission (IEC) and

the Versailles Agreement on Advanced

Materials and Standards (VAMAS). We

are developing new, calibrated measurements of power-dependent effects,

especially nonlinearity. We also investigate new materials and device structures for tunable microwave circuits.

Our goals for research on microwave and

millimeter wave devices in the next year are

to understand the source of undesirable

nonlinear behavior in HTS transmission lines

and resonators. We will measure materials

from companies making HTS filters so that

our results can be directly compared to

device performance.

We will continue to work on a standard for

measuring surface resistance at microwave

frequencies.

Cryogenic microwave probe station.

Bolometers and Junctions

We collaborate with industry to develop

and test HTS bolometers for applications

such as calibrated radiometers. We are

studying new hot-electron mixing effects

for detecting, synthesizing, and

frequency-converting THz radiation.

Applications include sensitive chemical

line spectroscopy, frequency chain

experiments in a solid-state system, and

specialized communication bands. We

are presently working on a long-term

effort to develop HTS Josephson

junctions for use as active components.

These may be used in voltage standards,

detectors, and integrated circuits that

meet the measurement and application

needs of industry.

We will use our existing research base in

bolometers on Si membranes and in

fabricating of submicrometer structures in

HTS films.

We will continue to develop HTS Josephson

junctions with controllable characteristic

voltages, VC. High VC is required for

terahertz mixing, detection, and generation,

while low VC is needed for voltage standards.

MEMS

MEMS and nano-electromechanical

systems (NEMS) are the enabling

technology for entire new generations of

electronic systems. Novel sensor and

metrology technologies benefit from the

ability to use integrated circuit

fabrication paradigms in constructing

mechanical devices.

Our focus in this area will be on

continuing current research efforts in

support of the Time and Frequency

Division while developing new

processes and applications.

Accomplishments

Microwave Measurements and Devices

! Loss and nonlinearity limit the utility

of HTS components in communications

applications — Superconductivity can

significantly improve the sharp band

edges of filters, reduce insertion loss in

most passive components, and eliminate

dispersion in transmission lines. HTS

materials have been improved to the

point that they rival their lowtemperature counterparts in surface

resistance, RS; however, power handling

and nonlinearity are not yet fully

understood or controlled in the

manufacturing environment.

The project has achieved significant

technical progress in three areas of

study. Working with international

standards organizations we are working

towards a standard for the measurement

of RS. New, calibrated measurement

techniques for power dependent effects,

especially nonlinearity, have been

developed. We have studied novel

devices for tuning microwave circuits by

investigating new materials and

structures. Our measurements are

performed with a unique cryogenic

microwave probe station to enable

A draft

international

standard for RS

using dielectric

resonators has been

written and roundrobin testing of HTS

films has begun.

MEMS and nanoelectromechanical

systems (NEMS) are

the enabling

technology for

entire new

generations of

electronic systems.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 21

precise characterization of patterned

devices.

! International Draft Standard – A

draft standard for RS using dielectric

resonators has been written, and roundrobin testing in Japan has begun. We

have completed the first set of comparative measurements in our laboratory.

Good agreement was observed in the

preliminary tests, and further improvements to the measurement apparatus are

underway.

! Measurement of nonlinearity in HTS

devices – We have developed a model

system to investigate the nonlinear

microwave response of HTS structures.

By measuring dimensions and

microwave properties of thin films

fabricated for a variety of purposes, we

are able to assist industry to improve

device performance. In particular,

calibrated power-dependent measurements have been made using a specially

modified vector network analyzer

! Intercomparison of nonlinearity – Using the measurement techniques we

have developed in collaboration with the

Naval Research Laboratory (NRL), we

have conducted a study of non-linearity

using four measurement tech-niques. We

have shown that there is a distributed

source of geometry-independent

nonlinearity that is clearly associated

with a current-dependent penetration

depth. These measurements span

frequencies from 2 KHz to 18 GHz. We

are now beginning to study devices

made from films produced by HTS filter

companies, with the goal of comparing

our measurements to the performance of

the filters made from identical thin films.

! Calibrated Measurements of

Ferroelectric Films – Using the

cryogenic probe station, we have studied

ferroelectric thin films for tunability and

loss. We have developed new and fully

calibrated measurement techniques that

will enable other groups to better

compare materials and devices.

View of two 40 GHz probes and a sample of

YBCO devices in the probe station.

Bolometers and Junctions

Bolometric applications use the sharp

transition to zero resistance at temperatures accessible by inexpensive

cryocoolers. The project developed the

first sensitive, composite, infrared

bolometer and demonstrated the lowest

noise temperatures for devices on

sapphire and silicon substrates. Our

recent work has been in developing

fabrication processes for terahertz

mixers and detectors. Josephson junction

research has focused on this area, as well

as working towards devices suitable for

use in arrays.

! HTS Devices on Si – We have

fabricated new HTS devices on Si for

testing of hot-electron mixing. Narrow

transition widths have been obtained in 1

μm to 2 μm structures; submicrometer

devices will be made.

! We have developed new HTS

Josephson junctions using a barriermodification process. Record-high VC

values (> 5 mV at 4 K) have been

achieved in narrow edge junctions. We

are also collaborating with several

groups in trying to develop junctions

capable of producing technologically

interesting arrays, such as needed for a

Josephson Arbitrary Waveform

Generator.

We have developed a

model system to

investigate different

HTS structures for

nonlinear microwave

response, and can

test a variety of thin

films, fabrication

processes, and

structure dimensions

to achieve improved

performance.

We have developed

new HTS Josephson

junctions using a

barrier-modification

process with record

high characteristic

voltages and

frequency response.
HTS Josephson junction with large characteristic

voltage. The edge junction is 0.9 μm wide

Micromachining and MEMS

! Micromachined Structures for Ion

Traps – We have made micromachined

structures for use in ion traps, in

collaboration with the Physics Laboratory’s Time and Frequency Division

(847). Division 847 has recently

demonstrated sub-dekahertz resolution

in the measurement of Hg low

resonance. Quantum entanglement has

been demonstrated with four ions in one

of these traps, as seen in the figure on

the above right.

! MEMS Facility – A new facility for

furnace processing has been completed

and is in routine use. The Nanoscale

Fabrication section of this book contains

a photograph of the tube furnaces. We

have developed improved cantilevers for

magnetometers in collaboration with the

EEEL Magnetics Group. We are

presently exploring collaborations to

work on MEMS and nano-electromechanical systems (NEMS) devices for

new metrological instruments.

Photograph of the central region of an alumina

micro-trap. The four trapped ions are seen in the

center of the image.

Recent Publications

H. Shimakage, R. H. Ono and L.R. Vale, “Interface

Engineered Josephson Junctions Optimized for High Jc,

IEEE Transaction on Applied Superconductivity (in press).

L.R. Vale and R. H. Ono, “Small Area, “Thin Films of

YBCO for Applications in Hot Electron Bolometers,” IEEE

Transaction on Applied Superconductivity (in press).

J. C. Booth, L.R. Vale, and R. H. Ono, “On-Wafer

Measurements of Nonlinear Effects in High Temperature

Superconductors,” IEEE Transaction on Applied

Superconductivity (in press).

J. C. Booth, L.R. Vale, R.H. Ono, and J.H. Claassen, “Power

Dependent Impedance of High Temperature Superconductors

Thin Films: Relation To Harmonic Generation,” James C.

Booth, L.R. Vale, R.H. Ono, and J.H. Claassen, J. Supercond.

(in press).

J. C. Booth, Leila R. Vale, and R. H. Ono, “Broadband

Determination Of Microwave Permittivity and Loss in

Tunable Dielectric Thin Film Materials,” in Materials Issues for Tunable RF and Microwave Devices, Proceedings,

Materials Research Society Symposium,Vol. 603, 253-264,

Q. Jia, Ed., Warrendale, PA (2000).

J. C. Booth, J. A. Beall, D. A. Rudman, L. R. Vale, and R. H.

Ono, “Geometry Dependence of Nonlinear Effects in High

Temperature Superconducting Transmission Lines at

Microwave Frequencies,” J. Appl. Phys. 86, 1020-1027 (July

1999).

J. C. Booth, and C. L. Holloway, “Conductor Loss in

Superconducting Planar Structures: Calculations and

Measurements,” IEEE Trans. Micro. Theory Tech. 47, 769-

773 (June 1999).

J. H. Claassen, J. C. Booth, J. A. Beall, D. A. Rudman, L. R.

Vale, R. H. Ono, “Nonlinear Inductive Response of High

Temperature Superconducting Films Measured by the Mutual

Inductance Technique,” Appl. Phys. Lett. 74, 4023-4025

(June 1999).

H. Shimakage, R.H. Ono, J.C. Booth and L.R. Vale, “Third

Harmonic Generation in Bicrystal Junctions,”

Superconductor Science and Technology 12, 830-832 (1999).

L.R. Vale, R.H. Ono, D.G. McDonald and R. Phelan, “Large

area YBCO Bolometers on Si,” Superconductor Science and

Technology 12, 856-858 (1999).

Quantum

entanglement of 4

ions has been

demonstrated in a

micromachined ion

trap.

22 Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 23

J. C. Booth, L. R. Vale, R. H. Ono, J. H. Claassen,

“Predicting Nonlinear Effects in Superconducting Microwave

Transmission Lines from Mutual Inductance Measurements,”

Superconductor Science and Technology 12, 711-713 (1999).

J. H. Claassen, J. C. Booth, J. A. Beall, D. A. Rudman, L. R.

Vale, and R. H. Ono, “Comparison of Microwave and

Mutual Inductance Measurements of the Inductive

Nonlinearity of HTS Thin Films,” Superconductor Science

and Technology 12, 714-716 (1999).

C. Weber, J.C. Booth, L. R. Vale, R. H. Ono, A.M. Klushin,

H. Kohlstedt, and R. Semerad, “Coplanar Transmission

Lines with Meandering Center Conductors in YBCO/Au

Bilayers Superconductor Science and Technology 12, 998-

1000 (1999).

Distributed Nonlinear Effects In Planar Transmission Lines,

James C. Booth, J.A. Beall, L.R. Vale, and R.H. Ono, 53rd

Automated RF Techniques Group (ARFTG) Digest, 31 - 40,

June 1999.

D. A. Rudman, F. J. B. Stork, J. C. Booth, J. Y. Juang, L. R.

Vale, G. J. Beatty, C. I. Williams, J. A. Beall, R. H. Ono, S.

B. Qadri, M . S. Osofsky, E. F. Shelton, J. H. Classen, G.

Gibson, J. L. MacManus-Driscoll, N. Malde, and L. F.

Cohen, “Role of Oxygen Pressure during Deposition on the

Microwave Properties YBCO Films,” IEEE Trans. Appl.

Supercond. 9, 2460-2464 (June 1999).

D. G. McDonald , R. J. Phelan, Jr., L. R. Vale, R. H. Ono,

and D. A. Rudman, “Passivation, Transition Width, and

Noise for YBCO Bolometers on Silicon,” IEEE Trans. Appl.

Supercond. 9, 4471-4474 (June 1999).

J. C. Booth, J. A. Beall, D. A. Rudman, L. R. Vale, R. H.

Ono, C. L. Holloway, S. B. Qadri, M. S. Osofsky, E. F.

Shelton, J. H. Classen, G. Gibson, J. L. MacManus-Driscoll,

N. Malde, and L. F. Cohen, “Simultaneous Optimization of

the Linear and Nonlinear. Microwave Response of YBCO

Films and Devices,” IEEE Trans. Appl. Supercond. 9, 4176-

4179 (June 1999).

H. Q. Li, R. H. Ono, L. R. Vale, D. A. Rudman, and S. H.

Liou, “Interactions Between Bicrystal Josephson Junctions in

a Multilayer Structure,” IEEE Trans. Appl. Supercond. 9,

3417-3420 (June 1999).

L. R. Vale, R. H. Ono, J. Talvacchio, M. G. Forrester, B. D.

Hunt, M. S. DiIorio, K-Y Yang, and S. Yoshizumi, “Long

Term Stability of YBCO Based Josephson Junctions,” IEEE

Trans. Appl. Supercond. 9, 3382-3385 (June 1999).
24

Nanoscale

Fabrication

Our facilities for fabricating integrated

circuits are essential to nearly all of the

work in the Division. We maintain a

research-class facility for superconductor and MEMS structures.

Beginning with computer aided design,

we use electron-beam and optical

lithography to make structures smaller

than 100 nm and complex circuits

containing as many as 32,000 Josephson

junctions. Our tools are housed in 200

m2 of “class 100” cleanroom space,

which was improved greatly in 1999.

We also added tools for fabricating

MEMS, which have been essential in the

past for many of our ultra-sensitive

instruments, and for micromachined ion

traps for future clocks. We are applying

these techniques to novel magnetic

instruments and photon detectors.

Jim Beall, Maggie Crews, and Jay Koch

in the lithography bay of the cleanroom.

Our near state-of-the-art facilities are

open-shop. All of our staff, and

occasional visitors, can personally use

them after appropriate training. Our

processes are flexible to avoid

constraining research activities to fixed

design rules and to allow maximum

creativity. Our past accomplishments are

testimony to the success of our

approach.

Computer-controlled research tube furnaces for

growth of SiO2, Si3N4, and other CVD materials.

For patterning at the 1 μm scale, we use

optical lithography in an I-line stepper

and a deep-UV contact aligner. Electronbeam lithography enables patterning at

less than 100 nm. Our facilities support

fabrication of superconductor integrated

circuits and MEMS fabrication, as well

as laser ablation of thin films of hightemperature superconductors. We

recently installed a set of tube furnace

reactors (5" capable), shown above, for

wet and dry silicon oxidation, solidsource boron diffusion, low-stress

silicon nitride/polysilicon low pressure

chemical vapor deposition (LPCVD),

and LPCVD of low-temperature oxide.

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 25

Appendix A:

Experimental Systems and Instruments

A partial list of our measurement facilities and capabilities follows:

! Experimental environments include a dilution refrigerator (DR) for temperatures down to

30 mK and adiabatic demagnetization refrigerators (ADR) for cooling to 50 mK. The DR

cools the capacitance standard to less than 50 mK and has special filtering to provide a

noise-free environment for the standard. See the Nanoscale Cryoelectronics Project

section of this book for more information on the capacitance standard based on counting

electrons.

Mark Keller (left) and John Martinis The microcalorimeter system connected

with the dilution refrigerator used for the to an SEM for x-ray analysis.

capacitance standard based on counting

electrons.

! Measurement systems include: high-speed electrical test facilities, an atomicforce microscope, a scanning electron microscope (SEM), high-resolution X-ray

materials analysis, X-ray structural analysis, a high-resolution mass spectrometer

with electrospray source, variable-temperature microwave probe station,

Josephson voltage standards, and tools for characterizating microwave loss in

thin films and detailed properties of infrared antennas. The figure on the above

right is a photograph of an ADR with an x-ray microcalorimeter spectrometer

attached to a commercial SEM.
26

Appendix B:

Postdoctoral Opportunities

NIST offers postdoctoral associateships in collaboration with the National Research Council

(NRC). Research topics and associated advisors for the Electromagnetic Technology Division

are listed below. Please see our Web site at http://emtech.boulder.nist.gov for full details on

each opportunity. Contact a prospective adviser to discuss details of proposed work and the

application process. If you do not find a topic that exactly matches your interest, please

contact an advisor in a similar discipline. U.S. citizenship is required for postdoctoral

appointments.

Research Topic Advisor(s)

Applications of Superconducting Integrated Circuits and Josephson

Junction Arrays

Sam Benz

DNA Sequencing Using a Cryogenic-Detector-Based Mass Spectrometer Gene Hilton

John Martinis

High-Resolution Microcalorimeters for X-Ray Microanalysis John Martinis

Dave Rudman

Gene Hilton

High-Tc Superconducting Thin Films for Devices Ron Ono

Dave Rudman

High-Tc Superconductors: Devices, Device Physics, and Circuits Ron Ono

High-Tc Superconductors: Microwave Properties and Devices Ron Ono

Physics and Applications of Single Electron Tunneling Devices Mark Keller

Superconducting and Nanometer-Scale Devices for Infrared to MillimeterWave ApplicationsErich Grossman

Superconducting Detectors for Photons from the Infrared through X Rays Kent Irwin

John Martinis

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 27

Appendix C:

Awards and Recognition

Notes: * indicates a coworker from outside the Electromagnetic Technology Division

Medal awards are from the U.S. Department of Commerce

Award Recipient Date Notes

William A. Wildhack

Award

Robert A. Kamper October,

1972

National Conference of Standards

Laboratories

Arnold O. Beckman

Award (ISA)

Robert A. Kamper 1974 Instrument Society of America, no citation

Gold Medal James E. Zimmerman and

Robert A. Kamper

October,

1975

For innovative contributions to practical

precise measurements using

superconducting quantum interference

devices (SQUIDs)

Industrial Research

-100 Award

Clark A. Hamilton, Robert

J. Phelan*, Gordon W.

Day*, John Geist*, and B.

McIntosh*

1975

NIST Condon Award Robert A. Kamper November,

1977

For distinguished achievement in written

exposition.

NBS Stratton Award James E. Zimmerman 1979

Silver Medal Clark A. Hamilton, Richard

E. Harris, Frances L. Lloyd,

and Robert L. Peterson

November,

1980

For creative advancement of the state of

the art in ultra-high-speed analog-to-digital

conversion.

NIST Condon Award Donald G. McDonald December,

1981

For distinguished achievement in written

exposition.

Silver Medal Michael. W. Cromar

Silver Medal Richard L. Kautz 1983 For fundamental contributions to the

understanding of chaotic behavior in

Josephson junction devices.

Gold Medal Clark A. Hamilton 1983 For outstanding contributions to the

development of ultra-high-speed Josephson

junction microcircuit technology.

NBS Fellow James E. Zimmerman 1984

EEEL Outstanding

Paper Award

Richard L. Kautz 1985 “Chaos and Thermal Noise in the rf-Biased

Josephson Junction,” Journal of Applied

Physics, Volume 58, Number 1 (1 July

1985).

NIST Stratton Award Richard L. Kautz and

Donald B. Sullivan

December,

1985

For exceptional accomplishments that

established the feasibility of a fundamental

improvement in the Josephson voltage

standard.

Research and

Development Magazine

Industrial Research

-100 Award

Clark A. Hamilton, Richard

L. Kautz and Frances L.

Lloyd

1986 For development of Josephson series array

voltage standards.

NBS Fellow Clark A. Hamilton 1987
28

NIST Gold Medal Clark A. Hamilton, Richard

L. Kautz, Frances L. Lloyd,

James A. Beall

October, 1989 For developing the first practical

Josephson-junction series array voltage

standards, at both 1 V and 10 V levels,

including the U.S. primary standard.

IEEE Fellowship Robert A. Kamper 1989 For leadership and technical contributions

to the application of superconductivity in

instrumentation, measurement, and

standards.

EEEL Outstanding

Paper Award

Samuel P. Benz and

Charles J. Burroughs

1991 “Coherent Emission from Two-Dimensional

Josephson Junction Arrays,” Appl. Phys.

Lett. 58(19): 2162-2164, May 1991

NIST Gold Medal High Temperature

Superconducting

Electronics Team: James

A. Beall, Todd E. Harvey,

Ronald H. Ono, David A.

Rudman, etc

October,

1993

For the world’s best Josephson junction

and associated practical technology to put

the U.S. in the lead for superconducting

electronics

Department of

Commerce Silver Medal

Robert A. Kamper 1993 For leadership of NIST’s Boulder

Laboratories and for excellent negotiating

skills in facilities development.

Harry Diamond

Memorial Award (IEEE)

Robert A. Kamper 1993 For pioneering the application of

superconducting quantum mechanical

principles to metrology, directing

development of advanced Cryoelectronics

devices, and guiding a metrology program

supporting the lightwave industry.

EEEL Outstanding

Paper Award

John M. Martinis, Michael

Nahum, and Hans

Dalsgaard Jensen

1994 “Metrological Accuracy of the Electron

Pump,” Physical Review Letters, Volume

72, Number 6, pp. 904-907 (7 February

1994)]

EEEL Outstanding

Paper Award

Mark W. Keller, John M.

Martinis, Neil M.

Zimmerman, and Andrew

H. Steinbach

1996 “Accuracy of Electron Counting Using a 7-

Junction Electron Pump,” Applied Physics

Letters, Volume 69, Number 12, pp 1804-

1806, 16 September 1996].

NIST Stratton Award John M. Martinis December,

1996

For applying new insights into quantum

phenomena to establish the fundamental

accuracy of Coulomb-blockage circuits for

single-electron counting

Silver Medal John Martinis December,

1996

For establishing the fundamental accuracy

of Coulomb-blockade circuits for singleelectron counting, providing the basis for

new intrinsic standards

EEEL Measurement

Services Award

Clark A. Hamilton February,

1995

EEEL Outstanding

Authorship Award

Mark W. Keller, John

M. Martinis, Neil

Zimmerman, and Andrew

H. Steinbach

February,

1997

“Accuracy of electron counting using a 7-

junction electron pump,” Appl. Phys. Lett.

69(12), 1804-1806, 16 September 1996.

Allen V. Astin Award

(National Conference

of Standards

Laboratories)

Samuel P. Benz, Clark A.

Hamilton, Charles J.

Burroughs, Todd Harvey,

and Lawrence Christian

1997 Josephson Standards for AC Voltage

Metrology

Fellow of American

Physical Society,

Condensed Matter

Physics

John M. Martinis November,

1997

For his experimental investigations into the

fundamental quantum behavior of lowtemperature electronic devices

Electronics and Electrical Engineering Laboratory
 Electromagnetic Technology Division 29

NIST Condon Award Richard L. Kautz December,

1997

For his extensive review of the physics of

the dc series array voltage standard in the

paper “Noise, chaos, and the Josephson

voltage standard,” which appeared in

Reports on Progress in Physics, vol. 59, pp.

935-992, Aug 1996.

Fellow of the American

Physical Society,

Precision Measurements

and Fundamental

Constants

Richard L. Kautz 1998 For experimental and theoretical

investigations of Josephson junctions,

particularly the nonlinear dynamics of

phase locking and chaos, essential to the

development of practical series-array

voltage standards.

Fellow of the American

Physical Society,

Precision Measurements

and Fundamental

Constants

Donald G. McDonald

EEEL Outstanding

Authorship Award

David A. Wollman, Kent D.

Irwin, Gene C. Hilton,

Laura L. Dulcie, Dale E.

Newbury, and John M.

Martinis

1998 “High-Resolution, Energy-Dispersive

Microcalorimeter Spectrometer for X-Ray

Microanalysis,” Journal of Microscopy,

Volume 188, Pat 3, pp. 196-223, December

1997

NIST Applied Research

Award

Gene C. Hilton, Kent D.

Irwin, John M. Martinis,

and David A. Wollman

December,

1998

For inventing an x-ray detector,

demonstrating its potential to revolutionize

x-ray microanalysis and developing it to the

point of commercialization

Gold Medal Gene C. Hilton, Kent D.

Irwin, John M. Martinis,

and David A. Wollman

December,

1998

For inventing a new x-ray detector,

showing its potential to revolutionize x-ray

microanalysis, and bringing it to the point

of commercialization.

EEEL Outstanding

Authorship Award

Mark W. Keller, Ali L.

Eichenberger, John M.

Martinis, and Neil M.

Zimmerman

1999 “A Capacitance Standard Based on

Counting Electrons,” Science, Vol. 285, 10

September 1999, pp 1706-1709

Presidential Early Career

Award for Scientists and

Engineers

Mark W. Keller October, 2000 "For his pioneering work in applying singleelectron tunneling (SET) quantum

mechanical principles to fundamental

electrical metrology, realizing the first SET

pump having parts per billion accuracy, and

demonstrating the feasibility of a SETbased capacitance standard."

NIST Condon Award Mark W. Keller, John M.

Martinis, Ali Eichenberger,

Neil Zimmerman

November,

2000

For distinguished achievement in written

exposition.
30

Appendix D:

Electromagnetic Technology Division Staff

(January to December, 2000)

Division Office

3776 Harris, Richard E. (Chief)

3678 Metz, Sara E. (Division Secretary)

3812 Schump, Jeanne (Admin. Officer)

3811 Majack-Sweet, Kate (Admin. Asst.)

3988 McCarthy, Sandy (Secretary)

5068 Copeland, Jill (Secretary)

Josephson Array Technology

5258 Benz, Sam (PL)

3906 Burroughs, Charlie

5211 Dresselhaus, Paul

3740 Hamilton, Clark (GR)

4153 Takada, Akio (GR)

Nanoscale Cryoelectronics

5081 Rudman, David (PL)

5557 Anders, Solveig (GR)

4137 Aumentado, Jose (PREP)

5344 Bergren, Norm

7644 Chervenak, Jay (Prep)

7457 Chiu, John (PHASE)

3461 Deiker, Steven (PD)

3418 Eichenberger, Ali (GR)

5679 Hilton, Gene

3402 Huber, Martin (IPA)

5911 Irwin, Kent

3841 Jehl, Xavier (GR)

3391 Kautz, Richard (GR)

5430 Keller, Mark

3597 Martinis, John

3148 Nam, Sae Woo (PD)

3021 Rabin, Michael (PD)

5221 Urbina, Cristian (GR)

7457 Wollman, David

7894 Xu, Yizi (Ctr)

High Performance Sensors,

Infrared Detectors, and Mixers

5102 Grossman, Erich (PL)

5102 Featherstone, Kelly (PHASE)

4199 Gerecht, Eyal (IPA)

3340 Harvey, Todd

3114 Nolen, Shalva (PD)

5052 Reintsema, Carl

High Tc Electronics

3762 Ono, Ron (PL)

5989 Beall, Jim

7900 Booth, Jim

5049 Crews, Maggie

7064 Koch, Jay

5113 McDonald, Don (GR)

7213 Shimakage, Hisashi (GR)

5121 Stevensen, David (PHASE)

5121 Vale, Leila

Division website:

http://emtech.boulder.nist.gov/

Email addresses for all staff are:

firstname.lastname@boulder.nist.gov

Legend:

Ctr = Contractor

GR = Guest Researcher

IPA = Interagency

Personnel Agreement

PD = Postdoctoral Appt.

PL = Project Leader

PREP = Professional

Research Experience Prog.

PHASE = Practical Handson Application to Science

Education

Telephone numbers are: (303)

497-XXXX (the four-digit

extension as indicated).

Electronics and Electrical Engineering Laboratory

January 2001

For additional information contact:

Telephone: (303)497-3678

Facsimile: (303)497-3066

On the Web: http://emtech.boulder.nist.gov/