bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecules with Multiple Personalities: How Switchable Materials Could Revolutionize Chemical Sensing
Authors: Benito-Lopez Fernando , Byrne Robert , Wu Yanzhe , Nolan Lorraine , Kim Jungho , Lau King Tong , Wallace Gordon G. , Diamond Dermot
Published: May 2009

Worldwide, the demand for sensing devices that can conform with the requirements of large-scale wireless sensor network (WSN) deployments is rising exponentially. Typically, sensors should be very low cost, low power (essentially self-sustaining), yet very rugged and reliable. At present, functioning WSN deployments involve physical transducers only, such as thermistors, accelerometers, photodetectors, flow meters, to monitor quantities like temperature, movement, light level and liquid level/flow. Remote, widely distributed monitoring of molecular targets remains relatively unexplored, except in the case of targets that can be detected directly using 'non-contact' techniques like spectroscopy. This paper will address the issues inhibiting the close integration of chemical sensing with WSNs and suggest strategies based on fundamental materials science that may offer routes to new sensing surfaces that can switch between different modes of behaviour (e.g. active-passive, expand-contract).
Zeolite Modification: Towards Discriminating Metal Oxide Gas Sensors
Authors: Binions Russell , Afonja Ayo , Dungey Sheena , Lewis Dewi , Parkin Ivan , Williams David E.
Published: May 2009

The use of zeolites to enhance the response and discriminating power of solid-state metal-oxide semiconductor gas-sensors is demonstrated. Thick film sensors were prepared by screen printing layers of tungsten trioxide (WO3) or chromium titanium oxide (CTO) with various zeolites as over-layers. The sensors' gas response was tested against two similar gases, ethanol and iso-propyl alcohol. The sensors are able to discriminate effectively between these two gases. The origin of this discriminatory behavior is elucidated through understanding the diffusion and reaction processes occurring in the zeolite transformation layer and sensor element.
Diversity in Sensing with Sensor Arrays: Hardware/Software for Artificial Senses
Authors: Stetter Joseph R.
Published: May 2009

With all of the great progress in chemical sensing and the prodigious literature on sensor arrays and the artificial chemical senses (nose and tongue), there is yet very much to learn about sensors and sensor arrays and their design and application. The signal in the artificial nose array starts with a simple chemical interaction of the sensor layer and the analyte producing an analytically relevant signal. The signal contains information about the nature and concentration of the analyte by virtue of the temporal, spatial, and parallel sensing process in an array. Extraction of the analytical information about the analyte may be accomplished by compensation, calibration, or computational modeling [algorithms] that extract the relevant part of the sensor signal.
Application of X-Ray Tomography to Optimization of New NOx/NH3 Mixed Potential Sensors for Vehicle On-board Emissions Control
Authors: Nelson Mark A. , Brosha Eric L. , Williamson Todd , Mukundan R. , Garzon Fernando
Published: May 2009

Mixed potential sensors for the detection of hydrocarbons, NOx, and NH3 have been previously developed at Los Alamos National Laboratory (LANL). The LANL sensors have a unique design incorporating dense ceramic-pellet/metal-wire electrodes and porous electrolytes. The performance of current-biased sensors using an yttria-stabilized zirconia (YSZ) electrolyte and platinum and La0.8Sr0.2CrO3 electrodes is reported. X-ray tomography has been applied to non-destructively exam internal structures of these sensors. NOx and hydrocarbon response of the sensors under various bias conditions is reported, and very little NOx response hysteresis was observed. The application of a 0.6 microamp bias to these sensors shifts the response from a hydrocarbon response to a NOx response equal for both NO and NO2 species at approximately 500 ºC in air.
Radionuclide Sensors and Systems for Environmental Monitoring
Authors: Grate Jay W. , O'Hara Matthew J. , Egorov Oleg B. , Burge Scott R.
Published: May 2009

We have developed automated sensor and monitoring devices for trace radionuclides in water, using preconcentrating columns and radiometric detection. The preconcentrating minicolumn sensor concept combines selective capture and detection in a single functional unit. We have demonstrated quantification of radionuclides such as technetium-99 to levels below drinking water standards in an equilibration-based process that produces steady state signals, signal proportional to concentration, and easy re-equilibration to new concentration levels. Alternatively, monitors can be developed with separate separation and detection units that are fluidically linked. We have demonstrated detection of strontium-90 to levels below drinking water standards by this approach. We are developing autonomous systems for at-site monitoring on the Hanford Site in Washington State.
Exploiting Nanobiophotonics for Enhanced Optical Biosensor Platforms
Authors: MacCraith Brian D. , McDonagh Colette , Stranik Ondra , Kurzbuch D. , Nooney R. , Le Guevel X.
Published: May 2009

In this presentation we describe strategies that will yield substantial enhancements in the analytical performance of fluorescence-based biochip platforms, especially for biomedical diagnostic applications. In particular, the focus is on optimisation of the signal-to-noise ratio (SNR) with a view to lowering the limit of detection (LOD). These strategies include exploitation of plasmonic effects and high-brightness doped-silica nanoparticles. The advantages offered by capturing supercritical angle fluorescence (SAF) are also covered.
Temperature Influence on Nanocrystals Embedded High-k Nonvolatile Memory Characteristics
Authors: Yang Chia-Han , Kuo Yue , Lin Chen-Han , Kuo Way
Published: May 2009

The temperature influence on memory functions of the nanocrystalline ZnO embedded Zr-doped HfO2 high-k capacitor was investigated. Both the memory window and the trapped charge density increased with the increase of temperature. The temperature effect on hole trapping was observed at 125åC but not at 25åC or 75åC. The temperature effect on electron trapping was obvious above 25åC. The interface quality is greatly influenced by the temperature, which was detected on the C-V, G-V, and I-V curves. The sample temperature affects the carrier generation and transport mechanisms, which are responsible for the memory function changes.
Flash Lamp Activation of n- and p-type Dopants in Strained and Unstrained SOI and HOI
Authors: Minamisava Renato A. , Buca Dan , Heiermann Wolfgang , Lanzerath Franz , Mantl Siegfried , Skorupa Wolfgang , Hartmann Jean-Michel , Ghyselen Bruno , Kernevez Nelly , Breuer Uwe
Published: May 2009

Strained Si and SiGe/Si heterostructures on insulator are promising channel materials for future nanoelectronics devices. The successful integration of these materials into new MOSFETs architectures depends on the ability of forming ultra shallow and ultra steep junctions for the source / drain regions. Here, we present results using flash lamp annealing for dopant activation in SOI, sSOI, HOI and sHOI. Flash lamp annealing technique allows complete suppression of diffusion while obtaining sheet resistances lower than 500 Ω/□, in both, SOI and sSOI. First investigations of strained and unstrained SiGe heterostructures after flash lamp annealing indicated significant diffusional broadening of Sb implant profiles and low electrical activation. In contrast, B shows higher activation but significant dopant loss in the near surface region.
Atomic Layer Deposition of Antimony Oxide on Hydrogen-terminated Silicon Substrates
Authors: Kalkofen Bodo , Matichyn Serhiy , Burte Edmund
Published: May 2009

Atomic layer deposition thin antimony oxide films on silicon substrates was investigated. Growth of small crystallites could be obtained by using triisopropylantimony (SbiPr3) and water. The deposition of thin continuous films succeeded after employing ozone and SbiPr3. The growth rate was significantly higher for the higher deposition temperature: 0.16 nm/cycle at 300 {degree sign}C compared to 0.06 nm/cycle at 200 {degree sign}C. X-ray photoelectron spectroscopy detected no impurities in the film other than adventitious carbon at surface. A composition ratio of antimony to oxide of 27/73 was found, suggesting the occurrence of the pentavalent oxide Sb2O5. The oxide is prone to sputter reduction during depth profiling. A chemical shift in the binding energy of the Sb photoemission peaks from the oxide to the Sb0 state clearly arises already after gentle argon sputtering. At temperatures up to 40 {degree sign}C the as-deposited films showed remarkably resistance to buffered oxide etch and nitric acid.
Photoluminescence Study on Ion Implanted Silicon after Rapid Thermal Annealing
Authors: Takashima Shuhei , Yoshimoto Masahiro , Yoo Woo Sik
Published: May 2009

The recrystallization process for ion implanted Si was characterized by photoluminescence (PL) at room temperature. By comparing the results of PL, four-point probe measurements, and current-voltage measurements of shallow pn junctions, we found PL a sensitive indicator, as intensity increased with even small decreases in sheet resistance of less than 10 ohm/sq. PL intensity also increased as ideality factor n and leakage current (of shallow p-n junctions) decreased. These results indicate a strong correlation between PL intensity and dopant activation. PL measurement is non-contact and non-destructive and can be used as an in-line monitor for dopant activation and crystalline damage recovery.
RF Sputtered Er2O3 Thin Films as High-k Gate Dielectrics for Germanium MOS Devices
Authors: Deepak G. C. , Bhat Navakanta
Published: May 2009

We report the material and electrical properties of Erbium Oxide (Er2O3) thin films grown on n-Ge (100) by RF sputtering. The properties of the films are correlated with the processing conditions. The structural characterization reveals that the films annealed at 550ºC, has densified as compared to the as-grown ones. Fixed oxide charges and interface charges, both of the order of 1013/cm2 is observed.
Fabrication of Suspended Ge-rich Nanowires by Ge Enrichment Technique for Multi-channel Devices
Authors: Saracco Emeline D. , Damlencourt Jean-Francois , Lafond Dominique , Bernasconi Sophie , Benevent Véronique , Rivallin Pierette , Morand Yves , Hartmann Jean-Michel , Gautier Pauline , Vizioz Christian , Ernst Thomas , Bonafos Caroline , Fazzini Pier Fransesco
Published: May 2009

This paper presents a new top-down method to fabricate Ge-rich nanowires for multi-channel devices by Ge enrichment technology. 3 dimensional Ge nanowire stacks have been fabricated and characterized by SEM, TEM, EDX. Nanowires obtained are single crystalline with no crystalline defects observed on cross-sectional TEM pictures. The main advantage of this method is that the shape, the size and the concentration of Ge nanowires can be tuned by process parameters. Indeed, depending on these parameters, nanowires with a Ge content up to 100% can be obtained with a very aggressive diameter (as low as 10nm). Moreover, this technology allows the co-integration of Ge and Si nanowires for pMOS and nMOS devices, respectively.
Dipole Model Explaining High-k/Metal Gate Threshold Voltage Tuning
Authors: Kirsch Paul D. , Sivasubramani Prasanna , Huang J. , Young C. D. , Park C. S. , Freeman K. , Hussain M. M. , Bersuker Gennadi , Harris Harlan R. , Majhi Prashant , Lysaght P. , Tseng H.-H. , Lee B. H. , Jammy R.
Published: May 2009

An interface dipole model explaining threshold voltage (Vt) tuning in HfSiON gated n-channel field effect transistors (nFETs) is proposed. Vt tuning depends on rare earth (RE) type and diffusion in Si/SiOx/HfSiON/REOx/metal gated nFETs as follows: Sr < Er < Sc+Er < La < Sc < none. This Vt ordering is very similar to the trends in dopant electronegativity (EN, dipole charge transfer) and ionic radius (r, dipole separation) expected for a interfacial dipole mechanism. The resulting Vt dependence on RE dopant allows distinction between a dipole model (dependent on EN and r) and an oxygen vacancy model (dependent on valence).
Hafnium Oxide Etching Using Hydrogen Chloride Gas
Authors: Habuka Hitoshi , Kobori Yoshitsugu , Yamaji Masahiko , Horii Sadayoshi , Kunii Yasuo
Published: May 2009

A chemical process for etching hafnium oxide was studied using hydrogen chloride gas. Hafnium oxide powder was used in order to clearly detect the occurrence of the chemical reaction. Amount of hafnium oxide powder decreased at temperatures higher than 600 K, which corresponds to the sublimation point of hafnium tetrachloride. Thus, the gaseous product of this chemical reaction is considered to be hafnium tetrachloride. The etching technique developed in this study is expected to be applied to various processes, such as the cleaning of the atomic layer deposition reactor for producing a thin hafnium oxide film.
Integration of Al Segregated NiSiGe/SiGe Source/Drain Contact Technology in p-FinFETs for Drive Current Enhancement
Authors: Sinha Mantavya , Lee Rinus T. P. , Devi Sivasubramaniam Nandini , Lo Guo-Qiang , Chor Eng Fong , Yeo Yee-Chia
Published: May 2009

This paper demonstrates the integration of a novel aluminum (Al) segregated NiSiGe/p+-SiGe S/D contact junction in strained tri-gate p-FinFETs for drive current enhancement. Al is introduced by ion implant into p+-SiGe S/D region followed by nickel deposition and germano-silicidation. Drive current enhancement of ~25 % is achieved in p-FinFETs without any degradation of device short channel effects. Devices with and without Al implant show similar threshold voltage, drain induced barrier lowering and subthreshold swing. The drive current enhancement is attributed to the lowering of the effective Schottky barrier height of holes (ΦBeffp) for NiSiGe on SiGe from 0.53 eV to 0.12 eV with the low dose Al implant of 2e14 atoms/cm2, leading to lowering of contact resistance at the NiSiGe/p+-SiGe S/D interface. Al present at the NiSiGe/p+-SiGe interface thins down the Schottky barrier width, which is responsible for the lowering of ΦBeffp.
UHV Fabrication of the Ytterbium Silicide as Potential Low Schottky Barrier S/D Contact Material for N-Type MOSFET
Authors: Yarekha Dmytro A. , Larrieu Guilhem , Breil Nicolas , Dubois Emmanuel , Godey Sylvie , Wallart Xavier , Soyer Caroline , Remiens Denis , Reckinger Nicolas , Tang Xiaohui , Laszcz Adam , Ratajczak Jacek , Halimaoui Aomar
Published: May 2009

Ytterbium silicide provides a low Schottky barrier height to electron on n-type silicon. This property makes this material very attractive for the realization of Source/Drain contacts for n-type MOSFETs. In this communication, the study of structural and electrical properties of YbSi2-x fabricated at different temperature in Ultra-High Vacuum condition without any protective layers is presented. N-type SB-MOSFETs with ytterbium silicide based S/D contacts were fabricated at optimal silicidation temperatures on SOI substrate with an ultra thin body.
Enhancement of Carrier Ballistic Transport in Schottky S/D MOSFETs
Authors: Wang Wei , Tsuchiya Hideaki , Ogawa Matsuto
Published: May 2009

In this paper, we study the influences of channel source-end potential profile on ballistic transport of carriers in Si-MOSFETs based on a quantum-corrected Monte Carlo device simulation. As a result, we found that a higher ballistic efficiency is expected in MOSFETs with a heterojunction source-end barrier such as Schottky source/drain (S/D) MOSFETs, than that of the conventional PN junction S/D MOSFETs. Such a superior ballistic behavior is demonstrated due to the narrower bottleneck barrier profile formed at the source-channel interface.
Ge/III-V Channel Engineering for Future CMOS
Authors: Takagi Shinichi , Sugiyama Masakazu , Yasuda Tetsuji , Takenaka Mitsuru
Published: May 2009

Mobility enhancement technologies have currently been recognized as mandatory for future scaled MOSFETs. In this paper, we present the basic concept on the choice of channel materials for high performance MOSFETs and address the expectation of Ge/III-V MOSFETs on the Si platform. We briefly review the present status and the critical issues of Ge/III-V MOS devices. Several key technologies, which are expected to make this heterogeneous integration of Ge/III-V MOSFETs possible, are introduced.
Improvement of Morphology and Free Carrier Mobility through Argon-Assisted Growth of Epitaxial Graphene on Silicon Carbide
Authors: Tedesco Joseph L. , VanMil Brenda , Myers-Ward R. L. , Culbertson James , Jernigan Glenn , Campbell Paul , McCrate J M. , Kitt S. A. , Eddy Charles , Gaskill D. K.
Published: May 2009

Graphene was epitaxially grown on both the C- and Si-faces of 4H- and 6H-SiC(0001) under an argon atmosphere and under high vacuum conditions. Following growth, samples were imaged with Nomarski interference contrast and atomic force microscopies and it was found that growth under argon led to improved morphologies on the C-face films but the Si-face films were not significantly affected. Free carrier transport studies were conducted through Hall effect measurements, and carrier mobilities were found to increase and sheet carrier densities were found to decrease for those films grown under argon as compared to high vacuum conditions. The improved mobilities and concurrent decreases in sheet carrier densities suggest a decrease in scattering in the films grown under argon.
Carbon Nanomaterials Standards Efforts at NIST
Authors: Fagan Jeffrey A.
Published: May 2009

Development of carbon nano-materials for applications has been hindered to date by a lack of standard protocols, i.e. documentary standards, and physical standards such as reference materials, which enable the common inter-comparison between laboratories, consumers and producers during property measurements and commerce. The National Institute of Standards and Technology (NIST) will soon be releasing several carbon nano-material standards, specifically for several forms of single-wall carbon nanotubes (SWCNTs), to promote commerce of these materials and to ease carbon nanomaterial development. The identification of the measurement need, development of the materials and specific areas of application are addressed.
Materials Science of Graphene for Novel Device Applications
Authors: Lee Geunsik , Gong Cheng , Pirkle Adam R. , Venugopal Archana , Lee Bongki , Park SeongYong , Goux Laurence , Acik Muge , Guzman Rodolfo , Chabal Yves J. , Kim Jiyoung , Vogel Eric M. , Wallace Robert M. , Kim Moon J. , Colombo Luigi , Cho Kyeongjae
Published: May 2009

Realization of graphene based devices will require a controlled integration of graphene into a device structure with multiple material components of metals and insulators. To investigate the fundamental materials problems of graphene devices, a complimentary team of researchers at UTD is applying experimental and theoretical methods to the graphene/metal and graphene/dielectric interface problems. To assess the large area graphene synthesis and the corresponding material properties, graphene oxides and grain boundaries in graphene are also examined by experiments in close connection with modeling study. Through a strong collaborative research in synthesis, characterization, and modeling, we have developed a fundamental understanding of graphene material properties which can facilitate diverse graphene based devices applications.
Novel Spectroscopic Platforms for Bio-Chemical Detection: Graphenated IR Screens
Authors: Banerjee Amrita , Moeller K. Dieter , Grebel H.
Published: May 2009

Screens or, metallo-dielectric meshes are periodic structures, designed to be at resonance with electromagnetic radiation. When the periodicity is on the micron scale, they enable transmission or, reflection of certain IR bands. Graphene is a monolayer thick crystal of carbon. It is mechanically strong and exhibits very large electronic mobility. Recently, we succeeded in fabricating mono and a few-layered suspended (free-standing) graphene on top of these screens. We combined these two unique components in fabricating novel platforms which enhance IR signals of soft bio-species.
Can Graphene be an Electrode Support for Pt in Formic Acid Electrooxidation?
Authors: Murugesan Sankaran , Myers Kirby , Subramanian Vaidyanathan R.
Published: May 2009

Formic acid electrooxidation over Pt deposited on two types of graphene supports are examined. The first support was prepared by rigorous chemical reduction of graphite oxide (GO) to form pure graphene (GCH). The second support is prepared by simultaneous reduction and functionalization of GO with ethylenediamine (GUE) by a one-step ultrasonication method. GUE show a significant shift in the HCOOH oxidation onset potential compared to GCH as well as other forms of commercial carbon supports. A comparative analysis of Pt activity towards formic acid electrooxidation over glassy carbon (GC) shows the following trend: Pt-GC-GUE>Pt-GC-GCH> HiSpec 3000 > Pt-GC-Vulcan XC-72.
Inter-band Tunnel Transistor Architecture using Narrow Gap Semiconductors
Authors: Mookerjea Saurabh , Krishnan Ramakrishnan , Vallett Aaron , Mayer Theresa , Datta Suman
Published: May 2009

The inter-band tunnel transistor (TFET) architecture features a sub-kT/q sub-threshold slope operation and can potentially support high ION/IOFF ratios over small gate voltages. Based on two-dimensional numerical simulations, we investigate TFET in various material systems ranging from silicon to indium arsenide. TFET performance can be enhanced when heterojunctions are employed at the source side to enhance tunneling, nonequilibrium carrier population is maintained in the channel and one dimensional tunneling junction are incorporated. Mixed mode circuit simulations using TFETs highlight the impact of feed forward gate-to-drain capacitance in these devices during transient switching operation and reveal important differences with MOSFETs. Narrow gap semiconductors with low density of states are projected as viable candidates to implement TFET architecture in sustaining an aggressive supply voltage scaling roadmap for future digital logic applications
Simulation of III-V HEMTs for High-speed Low-power Logic Applications
Authors: Liu Yang , Lundstrom Mark
Published: May 2009

In this paper a program to numerically simulate quantum transport in III-V HEMTs is described. The program uses a Green's function approach for ballistic transport in HEMTs designed for logic applications. The well-confined charge distribution in the quantum well permits an efficient mode space approach that dramatically lowers the computational burden. The program is described, and some results for an 80nm In0.7Ga0.3As HEMTs are presented as an example.
III-V/Ge Channel Engineering for Future CMOS
Authors: Wistey Mark , Singisetti Uttam , Burek Greg , Kim Eunji , Thibeault Brian J. , Nelson Austin , Cagnon Joël , Lee Yong-Ju , Bank Seth R. , Stemmer Susanne , McIntyre Paul C. , Gossard Arthur C. , Rodwell Mark J.
Published: May 2009

As silicon CMOS reaches its scaling limits, alternative materials become more attractive. Dielectric thickness and parasitic resistance and capacitance do not scale well, so "more than Moore" scaling is required even to keep up with Moore's Law. Replacing Si MOSFET channels on a short time scale (3-6 years) raises significant challenges for any proposed material or device structure. New materials must be compatible with Si CMOS fabrication. In(1-x)Ga(x)As based MOSFETs offer higher carrier velocities than Si, plus contact resistivities below 1E-8 ohm-cm^2, mature processing, and straightforward heterostructure confinement for vertical scaling, and additional degrees of freedom in composition and heterostructure for future scaling. Self-aligned source-drain regrowth places contact metal within 30 nm of the channel, reducing access resistance. Here we demonstrate InGaAs channels with self-aligned regrowth of source/drain contacts. This work led to depletion mode InGaAs MOSFETs with peak transconductance of 0.24 mS/micron.
Low Frequency Noise of Chlorine-treated GaN/AlGaN MSM-Photodetectors
Authors: Lu De-En , Chiou Ya-Lan , Lee Hsin-Ying , Lee Ching-Ting
Published: May 2009

Prior to the deposition of the Ni/Au interdigital electrodes, the GaN surface of GaN/AlGaN metal-semiconductor-metal (MSM) ultraviolet photodetectors was chlorine-treated. The low frequency noise equivalent power of the chlorine-treated photodetectors, measured at a bias of 5 V, was 5.13×10-10 W, which was one order of magnitude lower than that of the photodetectors without chlorination surface treatment. The normalized detectivity of the chlorine-treated photodetectors was 6.16×108 cmHz0.5W-1, which was higher than that of untreated one. The dark current of chlorine-treated and untreated photodetectors, operated at 5 V, was 1.45×10−11 A and 3.68×10−11 A, respectively. The performance improvement was attributed to the passivation of GaN surface by chlorination treatment.
The Evolution of Wide Bandgap Semiconductors at SOTAPOCS
Authors: Pearton Stephen J. , Ren F
Published: May 2009

At the 2009 San Francisco meeting, the State of the Art Program on Compound Semiconductors (SOTAPOCS) will be held for the 50th time. This manuscript provides some personal recollections of the place that wide bandgap materials have played after the early days of the symposium were focused mainly on GaAs and InP materials and devices and how this highlights the corresponding maturation of the compound semiconductor industry.
AlGaN/GaN High Electron Mobility Transistors integrated into Wireless Detection System for Glucose and pH in Exhaled Breath Condensate
Authors: Chu Byung Hwan , Kang Byoung Sam , Chang C.Y. , Ren F , Goh Aik , Sciullo Andrew , Wu Wenhsing , Lin Jenshan , Gila Brent P. , Pearton Stephen J. , Johnson J. W. , Piner E.L. , Linthicum K.J.
Published: May 2009

Peltier element cooling is demonstrated to be an effective method for collecting exhaled breath condensate (EBC) on AlGaN/GaN High Electron Mobility Transistors (HEMT). The HEMT sensors have functionalized gate areas for glucose and pH measurement. The current change measured in the HEMTs with EBC shows that the sensitivity of the glucose detection is lower than the glucose concentration in the EBC of healthy person and the pH measurement range includes 7- 8, typical of that for human blood. The sensors can be integrated into a wireless data transmission system that allows remote monitoring. Details of the transmitter and receiver design for the transmission system are given. Our work demonstrates the possibility of using AlGaN/GaN HEMTs for extended investigations of airway pathology without the need for clinical visits.
Electrodeposited Au-CdTe-Au Nanowires: Solution-based Control Over Cd/Te Stoichiometry
Authors: Mair Lamar O. , Skinner Kwan , Donley Carrie , Superfine Richard
Published: May 2009

Heterostructured, composition-adjusted Au-CdTe-Au nanowires were fabricated via templated electrodeposition. Cd/Te ratios were modified in the wires by varying the Te4+ concentration in the deposition electrolyte. These wires were characterized by energy-dispersive x-ray spectroscopy (EDS); subsequently, they were deposited onto Si/SiO2 substrates and electrically contacted using Pt deposition in a focused ion beam tool. EDS and photoelectron x-ray spectroscopy (XPS) were used to characterize the composition and surface chemistry of CdTe films deposited from the various electrolytes.
Annealing Effects on ZnO/NiSi Contact
Authors: Wei Ren , Gong Hao
Published: May 2009

NiSi as the electrode of ZnO films was annealed for different temperatures. It was found that with the increase of the temperatures, although the structure quality of ZnO films does not change greatly, the optical properties of the films do indicate the introduction of the oxygen defects into ZnO films by annealing process.
Electrophoretic Deposition of Spherical and Rod-Shaped Nanocrystals into Close Packed Superlattices
Authors: Ahmed Shafaat , Barrett Christopher A. , O'Sullivan Catriona , Sanyal Ambarish , Geaney Hugh , Singh Ajay , Gunning Robbie D. , Ryan Kevin M.
Published: May 2009

Ordered nanocrystal assemblies are an exciting new class of materials where electronic, optical or magnetic properties can be dictated by tuning the position and ligand environment of each nanocrystal structural unit. Device integration in both nanoelectronics and nanophotonics relies on the ability to locate these ensembles with nanoscale accuracy exactly where they are needed. In this paper we overview our recent work in the area of electrophoretic deposition of charged nanocrystals from toluene.(1, 2) The systems discussed are twofold 1: gold nanocrystals (8 nm) which are positively charged and assembled from a toluene solution with unprecedented selectivity into lithographic channels and 2: CdS nanorods (100 nm × 8 nm) which are negatively charged and assembled into perpendicularly oriented nanorod superlattices over centimeter squared areas suitable for nanorod solar-cells.
Spontaneous Deposition of Metallic Pt onto n-InP: An Electroless Process
Authors: Etcheberry Arnaud , Mathieu Charles , Bouttemy Muriel , Vigneron Jacky , Tran-Van Pierre , Goncalves Anne-Marie
Published: May 2009

InP surface are treated in K2PtCl4 dissolved in pure water. A spontaneous electroless process is observed with interesting residual Pt(0) coverage an correlated InP oxidation. The demonstration of this effect is given by high resolution XPS. Modifications are also detected using capacitance measurement on the interface.
Deconvolution of the Potential and Time Dependence of Electrochemical Porous Semiconductor Formation
Authors: Quill Nathan , O'Dwyer C. , Lynch Robert , Buckley D. N.
Published: May 2009

A layer of porous InP is grown beneath a thin dense surface layer when n-InP electrodes are anodised to sufficiently high potentials in aqueous KOH solutions. The shape of the linear sweep (LSV) or the cyclic voltammogram (CV) is dependent on carrier concentration. A technique is presented to deconvolute the effects of potential and time on a CV. The results obtained from this technique are used to explain the shape of the anodic current response and it relation to porous layer formation. The accuracy of the deconvolution technique is then tested by comparison to experimental results.
Advanced Analysis of Silicon Insulator Interface Traps in MOSFET's with SiO2 and HfO2 as Gate Dielectrics
Authors: Bauza Daniel , Ghobar Oussama , Guénifi Naima , Bayon Sébastien
Published: May 2009

In this paper and using the charge pumping method, it is shown that in state-of-the-art fully processed MOSFET's the Si-SiO2 interface traps have the same properties as those of the Pb0 center. The question as to whether these defects are Pb0 centers is discussed. Devices using HfO2 as gate dielectric are also studied. In spite of some differences, it is found that the traps at the Si-SiO2 interface in these devices have the same properties as those in state-of-the-art fully processed MOSFET's. These differences are discussed. Finally, a method for extracting the interface trap density from the slope of the charge pumping curves is proposed and applied to the two kinds of devices studied.
The Role of the Interfaces in the 1/f Noise of MOSFETs with High-k Gate Stacks
Authors: Crupi Felice , Magnone Paolo , Simoen Eddy , Pantisano Luigi , Giusi Gino , Pace Calogero , Claeys Cor
Published: May 2009

This paper focuses on the impact of the gate and substrate interfaces on the 1/f noise of the drain and the gate current of MOSFETs with high-k gate stacks. Three case studies are critically discussed to highlight the key role played by both interfaces in the 1/f noise. First, we show how a sub-monolayer of HfO2 sandwiched between SiON gate dielectric and poly-Si gate significantly increases the 1/f noise. The second case study indicates that a LaO cap on top of HfSiON significantly decreases the 1/f noise. The third experiment shows that the 1/f noise can be reduced by increasing the thickness of a SiO2 interfacial layer sandwiched between the substrate interface and the HfO2 layer.
Impact of Minorty Carrier Response on Characterization of Ge MIS Interface Traps
Authors: Taoka Noriyuki , Mizubayashi Wataru , Morita Yukinori , Migita Shinji , Ota Hiroyuki , Takagi Shinichi
Published: May 2009

The response of majority and minority carriers with interface traps have been systematically investigated for Ge MIS interfaces with various interface layers by the conductance method based on the conventional model including the only majority carrier response and a newly-proposed model including the both carrier responses with interface traps. The analysis by using the conventional model leads to the inappropriate results of the Ge MIS interface properties near room temperature. On the other hand, the proposed model can accurately characterize ones. As a result, the electron capture cross-sections hardly depend on the energy in all samples as similar with those of Si MOS interface traps. This result indicates that the similar defects to a Si MOS interface are formed at the Ge MIS interfaces. Furthermore, the magnitudes of the cross-sections for each sample depend on the oxygen or nitrogen contents of the interface layers, suggesting that the different defect structures exist.
Negative-Bias Temperature Instability: Measurement and Degradation Mechanisms
Authors: Ang Diing Shenp , Hu You Zhou , Teo Zhi Qiang , Du Guo An , Lai Simon Chung Sing , Ho Terence Jun Jie
Published: May 2009

This paper addresses two important aspects of negative-bias temperature instability (NBTI), namely measurement methodology and degradation mechanisms. An improved ultra-fast switching measurement method with sub-100 ns delay is presented. The method is based on customary pulsed current-voltage equipment and thus provides an attractive standard for NBTI measurement. Both linear and subthreshold drain current measurements are discussed and the relevant limitations addressed. In the discussion, it is shown that the gate voltage shift extracted through the computation of integral (dId,lin/gm) grossly over-estimates the threshold voltage shift |DVt| (i.e. the fraction of gate voltage shift due to interfacial trapped charge) because of mobility degradation. Ignoring this effect results in an unduly pessimistic assessment of interfacial trapped charge generation. We propose a better method that could delineate both |DVt| and low-field mobility degradation. In addition, results which indicate two distinct degradation mechanisms are presented. Experimental evidence that shows a "bipolar" (i.e. both acceptor- and donor-like) characteristic of stress induced interface traps is discussed. Finally, features of dynamic NBTI which do not conform to the reaction-diffusion model are highlighted.
The Dielectric Breakdown in Gate Oxides under High Field Stress
Authors: Lombardo Salvatore A. , Stathis James H. , Bersuker Gennadi
Published: May 2009

We review some experimental data on the dielectric breakdown (BD) phenomenon under high field stress of important gate insulators used in MOSFETs. We first discuss the case of silicon oxides or oxynitrides in the thickness range of tens of nm down to about 1 nm focusing on the kinetics of the final hard BD event.We describe the dependence of the BD current transient on the oxide thickness and the electric field and voltage. In particular we focus on the progressive BD phenomenon, i.e., a gradual growth of the BD leakage occurring in a time scale which in operation conditions is relevant. We then discuss the BD phenomemon in the case of ultra-thin high polarizability constant (high-k) dielectrics with metal gates in comparison to the conventional SiO2/poly-Si devices and outline critical differences between these gate stacks.
Critical Modeling Issues in Negative Bias Temperature Instability
Authors: Grasser Tibor , Goes Wolfgang , Kaczer Ben
Published: May 2009

Both the physical mechanisms as well as the modeling of negative bias temperature instability (NBTI) have attracted growing attention during the last years. While the reaction-diffusion theory had been the dominant explanation for a relatively long period, a growing number of authors have recently voiced their doubts regarding its validity. We give a brief review of suggested models and highlight their strengths and, more importantly, their weaknesses. We take care not to get lost in the intricacies of the various models by only qualitatively discussing their features. As will be shown, this is more than sufficient to demonstrate considerable shortcomings. Finally, we summarize our latest modeling attempts which try to overcome the observed modeling contradictions and show comparisons to experimental data.
Performance, Reliability, Radiation Effects, and Aging Issues in Microelectronics - From Atomic-Scale Physics to Engineering-Level Modeling
Authors: Pantelides Sokrates T. , Tsetseris Leonidas , Beck Matthew J. , Rashkeev Sergey N. , Hadjisavvas George , Batyrev Iskander , Tuttle Blair , Marinopoulos Apostolos G. , Zhou Xing , Fleetwood Daniel M. , Schrimpf Ronald
Published: May 2009

The development of engineering-level models requires adoption of physical mechanisms that underlie observed phenomena. This paper reviews several cases where parameter-free, atomic-scale, quantum mechanical calculations led to the identification of specific physical mechanisms for phenomena relating to performance, reliability, radiation effects, and aging issues in microelectronics. More specifically, we review recent calculations of electron mobilities that are based on atomic-scale models of the Si-SiO2 interface and elucidate the origin of strain-induced mobility enhancement. We then review extensive work that highlights the role of hydrogen as the primary agent of reliability phenomena such as Negative Bias Temperature Instability (NBTI) and radiation effects, such as Enhanced Low Dose Radiation Sensitivity (ELDRS) and dopant deactivation. Finally, we review atomic-scale simulations of recoils induced by energetic ions in Si and SiO2. The latter provide a natural explanation for single-event gate rupture (SEGR) in terms of defects with energy levels in the SiO2 band gap.
Characterization of Threshold Voltage Shift by Negative Bias Temperature Stress in HfSiOx Films
Authors: Tamura Chihiro , Hayashi Tomohiro , Kikuchi Yuuki , Ohmori Kenji , Hasunuma Ryu , Yamabe Kikuo
Published: May 2009

Threshold voltage shift by negative stress voltage application in HfSiOx films was investigated. It was found that the threshold voltage shift was summation of the voltage shifts due to interface state generation and generation of traps. It was revealed that the contribution of trap generation, which rapidly increases with small amount of hole injection, was the most influential component in a short term. In a long term, on the other hand, the trap generation which proceeds linearly with the amount of hole injection becomes the dominant component, since it does not saturate for long period.
Stress Changes in Silicon Nitride Thin Films on Thermal Cycling and Deconvolution of Separate Contributions
Authors: Ekwal Sah R. , Baumann H.
Published: May 2009

A correlation between stress in amorphous silicon nitride films and their composition has been established. This has led to the deposition of low-stressed films at low temperatures. The density of the films calculated from the results of Rutherford Backscattering Spectroscopy and Nuclear Reaction Analysis techniques is high, around 2.4 g/cm3, indicating a dense network. The films exhibit relatively high coefficient of thermal expansion, around 3.2 ppm/{degree sign}C, indicating a fairly short-range order in the film. Furthermore, a reversible thermally induced stress, i. e., a negligible stress hysteresis upon thermal cycling between room temperature and 400{degree sign}C has been observed in the film. From the stress response of the films to the thermal cycling separate contributions from the thermal and athermal components to the net room temperature stress have been deconvoluted.
Synchrotron X-ray Diffraction Studies of Thermal Oxidation of Si and SiGe
Authors: Shimura Takayoshi , Okamoto Yuki , Shimokawa Daisuke , Inoue Tomoyuki , Hosoi Takuji , Watanabe Heiji , Sakata Osami , Umeno Masataka
Published: May 2009

Thermal stability and the electron irradiation damage to the ordered structure in the thermal oxide on Si substrates are shown, together with the fundamentals of the quasi-amorphous structural model. The mechanism and rate enhancement of SiGe oxidation is also discussed based on the ordered structure in the oxide layer.
High K Dielectrics for Future CMOS Devices
Authors: Robertson John
Published: May 2009

The properties and materials selection of high dielectric constant oxides and metals for advanced CMOS FETs are reviewed. The basic problems of high K oxides and metal gate stacks have been implemented in practical devices by a number of industrial groups. The control of the FET gate threshold voltage and its effective work function has been difficult to achieve. Atomistic models of factors affecting the effective work function are described.
Advances on III-V MOSFET for Science and Technology beyond Si CMOS
Authors: Kwo J. R. , Lin T. D. , Huang M. L. , Chang P. , Lee Y. J. , Hong M.
Published: May 2009

An overview is given on recent advances of science and technology of InGaAs MOS and MOSFET. Firstly, Fermi level unpinning in atomic layer deposited (ALD) oxides on InGaAs was discussed. The energy parameters in the oxides/InGaAs were determined. Secondly, we have achieved low interfacial densities of states, low electrical leakage currents, and high-temperature thermal stability. The scaling of the high κ oxides approaching 1.0 nm capacitance equivalent thickness (CET) is achieved in the Ga2O3(Gd2O3) [GGO]/In0.2Ga0.8As (InGaAs) gate stack. Finally, we have demonstrated a self-aligned inversion-channel In0.53Ga0.47As MOSFETs made of Al2O3(2nm)/GGO(5nm) gate oxide and TiN metal gate at 1 μm gate length, reaching a world record of drain current and transconductance.
Inversion-Mode Inxga1-Xas Mosfets (X=0.53,0.65,0.75) with Atomic-Layerdeposited High-K Dielectrics
Authors: Ye Peide , Xuan Yi , Wu Yanqing , Xu Min
Published: May 2009

High-performance inversion-type enhancement-mode (E-mode) n-channel MOSFETs on In-rich InGaAs using ALD Al2O3 as high-k gate dielectrics are demonstrated. The maximum drain current, peak transconductance, and the effective electron velocity of 1.0 A/mm, 0.43 S/mm and 1.0x107 cm/s at drain voltage of 2.0 V are achieved at 0.75-μm gate length devices. The device performance of In-rich InGaAs NMOSFETs with different indium contents, In0.53¬Ga0.47As, In0.65Ga0.35As and In0.75Ga0.25As, are systematically studied and compared. Deep submicron inversion-mode In0.75Ga0.25As MOSFETs with ALD high-k Al2O3 as gate dielectric are also demonstrated by the full electron beam lithography process. N-channel MOSFETs with 100 nm to 200 nm-long gates have been fabricated. At a supply voltage of 0.8 V, the fabricated devices exhibit drain currents of 260 μA/μm to 801 μA/μm and transconductances of 540 μS/μm to 950 μS/μm. Important scaling metrics, such as on/off current ratio, sub-threshold swing, and drain-induced barrier lowering are presented and their relations to the short-channel effect are discussed. Although on-state performance of InGaAs MOSFETs, such as drain current and trans-conductance, shows great opportunities for III-V MOSFET for future logic applications, great challenges could still exist on off-state performance limited by the implanted junction leakage and donar-type interface traps at high-k/InGaAs interfaces.
A Mass-Production Compatible Capacitor Technology for DRAMs with Design Rule Down To 20 nm
Authors: Choi Gyu Jin , Kim Seong Keun , Han Jeong Hwan , Lee Sang Woon , Hwang Cheol Seong
Published: May 2009

TiO2 and Al-doped TiO2 (ATO) films were studied as the capacitor dielectrics for the dynamic random access memory devices with the design rule of < 40 nm. These materials grown on the variously processed Ru electrode showed a very promising electrical performances; a minimum equivalent oxide thickness of 0.48 nm with the safe leakage current density. The crystal structure, role of the interface with the Ru electrode on the phase formation of TiO2, TiO2 process conditions for achieving the optimized film property, Al-doping effect, plasma-process for the TiO2 and ATO film and the adoption of Ru/TiN double layer electrode for the mass-production compatibility are dealt with in this article. The crucial influence of the precursor (RuO4) for the Ru electrode deposition is also described.
Permeabilities of Inorganic Thin Composite (Sio2)1-X(Zno)X Films Prepared by RF-magnetron Sputtering Method
Authors: Kim Hwamin , Sohn Sunyoung
Published: May 2009

Diatomic inorganic films of SiO2 and ZnO and their composite films were prepared by the RF-magnetron sputtering to investigate their permeabilities. The Ca cells tested in the atmosphere resulting in a gradual progress of transparency in the passivated Ca cells, which was represented by changes of the optical transmission spectrum. Comparing the saturation times for Ca cells to become completely transparent, the protection effects against water vapor were evaluated for various passivation films. The (SiO2)1−x(ZnO)x films were found to show a superior protection effect, in this study, we investigate the dependence of the composition ratio on the permeability of the (SiO2)1−x(ZnO)x films with a low water vapor transmission rate (WVTR) as a gas barrier layer for flexible displays. And an extremely low WVTR less than 10−3 g/m2/day was obtained in the (SiO2)1−x(ZnO)x(x=0.5, 0.7, and 0.9 at.%) films with high packing density and polarizability.
Temperature Stress Response of Germanium MOS Vapacitors with HfO2/HfSiON Gate Dielectric
Authors: Arora Rajan , Schmidt B. W. , Fleetwood Daniel M. , Schrimpf Ronald , Galloway Kenneth , Rogers Bridget , Chung K. B. , Lucovsky Gerald
Published: May 2009

Temperature and electrical stress induced degradation in the characteristics is reported for germanium substrate MOS capacitors with HfO2/HfSiON gate dielectrics. The accumulation capacitance decreases with temperature stress due to diffusion of germanium into the high-κ dielectric. The interface trap and border trap densities decrease due to temperature stress-induced oxide growth at the oxide-germanium interface.
Self-Consistent Technique for Extracting Density of States in Amorphous GaInZnO Thin Film Transistors by Combining an Optical Response of C-V Curve and Gate Voltage-Dependent Intrinsic Channel Mobility
Authors: Park Jun-Hyun , Jeon Kichan , Lee Sangwon , Kim Sunil , Kim Sangwook , Song Ihun , Kim Chang Jung , Park Jeachul , Park Youngsoo , Kim Dong Myong , Kim Dae Hwan
Published: May 2009

The self-consistent technique for extracting density of states (DOS: g(E))in amorphous Gallium-Indium-Zinc-Oxide (a-GIZO) thin film transistor (TFT) is proposed and demonstrated. While the energy level (E) is scanned by the photon energy and the gate voltage (VGS) sweep, its density is extracted from the optical response of capacitance-voltage (C-V) characteristics. The preliminary DOS assuming the linear relation between VGS and E is translated into the final DOS by fully taking nonlinear relation between VGS and E into accounts. It is finally extracted and verified by finding the self-consistent solution satisfying both the preliminary DOS and the measured VGS-dependence of intrinsic channel mobility (uCH) with the numerical iteration of DOS-based uCH model. final DOS parameters are NTA=1.73×1017 [cm-3 eV-1], NDA=3.5×1015 [cm-3 eV-1], kTTA=0.023 [eV], kTDGA=1.2 [eV], and EO=1.7 [eV] with the formula of exponential tail states and Gaussian deep states.