bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Low Specific Ohmic Contact Resistivity of Alloyed Ge—LOW—Content Au on Si—Implanted Electrically—Active GaAs Crystal Layers
Authors: Saito Yasuyuki 
Published: March 2011

ABSTRACTThe author did experiments on ohmic contacts between alloyed goldgerumanium (AuGe) thin film systems and Si–implanted n–type GaAs crystal conductive layers on semi–insulating wafers in order to obtain stable ohmic contacts for source–drain electrodes of Si–implanted metal–semiconductor field–effect–transistor arrays as the tools of investigating semi-insulating GaAs crystallographic–characteristics uniformity. Hot–stage–alloyed low–Ge–content (content in charged AuGe wire: < a few wt.%) AuGe/Au films and GaAs crystal n–type Si–implanted layers showed smooth metallic surface morphology (like gold reflection) and low specific ohmic resistivity (≃10exp.−6 Ω/cm2) (by G.S.Marlow and M.B.Mukunda method) at Room temperature on the condition of typical 0.25 X 10exp.13/cm2− 1 X 10exp.13/cm2 Si dosage at 100keV–200keV and 850°C-15 min capless annealing in 2.7 Torr AsH3+Ar atmosphere for S.I GaAs crystal wafers.
An Optimization Study of Thermal Stability of W/GaAs Schottky Gates
Authors: Favoretio Marcio , Swart Jacobus W. 
Published: March 2011

ABSTRACTThis paper presents an experimental study of the physical and electrical characteristics of tungsten (W) thin films versus the deposition parameters of sputtering. A correlation between the W film characteristics and thermal stability of the W/GaAs Schottky diodes is also presented. Good thermal stability was obtained for W gates with low resistivity and α-W phase, deposited at low pressure and low RF power. W films deposited at high pressure presented high resistivity, β-W phase and weak thermal stability. Diodes annealed under As over-pressure ambient presented an enhanced thermal stability of about 100°C.
Fabrication, Performance, and Reliability of InP-Based HBTs
Authors: Stanchina William E. , Metzger Robert A. , Jensen Joseph F. , Hafizi Madjid , Rensch David B. 
Published: March 2011

ABSTRACTOver the past 10 years, heterojunction bipolar transistors (HBTs) have progressed to where integrated circuit (IC) products are being sold and foundry services are being commercially offered utilizing gallium arsenide (GaAs) based technology. We will discuss, here, an alternative HBT technology based on indium phosphide (InP). While this technology is less mature than its GaAs counterpart, it offers several attractive benefits in comparison with GaAs. These benefits are provided through several key material properties of InP and ternary compound semiconductors, eg. gallium indium arsenide (GaInAs), grown on the InP. We review the status of this npn HBT technology and present performance results which illustrate the benefits of the technology with respect to electronic applications. Finally, we present measured reliability data for this technology which shows outstanding projected lifetimes.
Reliability of Implant-Isolation Regions in Highly-Doped GaAs-Based Structures
Authors: Ren F. , Pearton S. J. , Lothian J. R. , Fullowan T. R. , Abernathy C. R. , Chu S. N. G. 
Published: March 2011

ABSTRACTHighly-doped n-type (2 × 1019 cm−3) and p-type (7 × 1019 cm−3) GaAs layers were implanted with multiple energy F+ or H+ ions and subsequently annealed at ∼550°C to produce high resistance regions. The resistance of these layers at 200°C was monitored as a function of time and showed no changes for periods of several months. This is in contrast to some previously reported data, which showed complete loss of isolation after a period of several days in proton-implanted n+ GaAs. Here, we show that isolation of heavily-doped near-surface regions by protons requires implantation through cap layers which place the peak of the nuclear stopping profile at the GaAs surface. The application of these results to isolation of thick, multilayer heterostructure devices is discussed and SIMS and TEM data are used to illustrate the redistribution of the implanted ions and the defects they create, respectively.
Differential Reflectance Studies of Structural Changes in GaAs Caused by Ar+ Ion Bombardment
Authors: Ludwig M. H. , Hummel R E. 
Published: March 2011

ABSTRACTDifferential reflection (DR) spectrometry has been used to investigate and characterize the effect of sputter damage of GaAs by Ar+ ions. The DR technique provides the photon-induced critical point interband transition energies which are sensitive to the electron and the crystal structure. The spectral dependence of the normalized difference in reflectivity is obtained by periodically scanning monochromatic light across a pair of GaAs samples. In the present case one part has been damaged by Ar+ ions with energies ranging from 500 to 5000 eV. The other half is the undamaged reference. The DR structure caused by interband transitions and designated as E1 and E1 + δ1 were found to shift in energy with increasing ion beam energy or with sputter damage. Two annealing stages were observed, one at 200°C and the other between 400°C and 450°C. They were attributed to different recovering mechanisms of As Frenkel pairs.
Time Dependent Diffusion of P-Type Dopants in Gallium Arsenide
Authors: Robinson H.G. , Jones K.S. , Deal M.D. , Hu C.J. 
Published: March 2011

ABSTRACTThe diffusion of implanted p-type dopants in GaAs often exhibits transient effects during annealing. This diffusion can greatly affect device performance and must be understood in order to create accurate, physically based process modeling simulation tools for compound semiconductors. The transient diffusion is believed to be related to defects created during implantation, but a direct correlation between implant damage and dopant redistribution has been difficult to establish. Results are presented in this paper of experiments designed to gain insights into the fundamental mechanisms underlying the relationship between defects and diffusion. Many anomalies in previous data are the result of implanting dopants under poorly controlled conditions, particularly implant dose rate and temperature. Special care was taken in this work to ensure that the implants were performed under well controlled conditions. Al was co-implanted with Mg and Be to study the effect of implant damage without affecting the position of the Fermi level. A correlation was found between the initial transient diffusion observed in low dose Be implants and the presence of dislocation loops. This may present a viable method for suppressing diffusion of implanted Be. SIMS profiles of Mg and Al co-implants were anomalous and difficult to interpret. Cap failure, dopant segregation to the surface and/or defects may be responsible for the discrepancies in the data. P-type doping appears to stabilize dislocation loops, probably by increasing the concentration of positively charged Ga interstitials. RBS measurements of implanted Mg indicates a link between damage production, implant dose rate, and diffusion. This result agrees with previous work on damage production in Si implanted GaAs.
Comparison of AlN films grown by RF magnetron sputtering and ion-assisted molecular beam epitaxy
Authors: Chan J. , Fu T. , Cheung N. W. , Ross J. , Newman N. , Rubin M. 
Published: March 2011

ABSTRACTCrystalline aluminum nitride (AIN) thin films were formed on various substrates by using RF magnetron sputtering of an Al target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AIN/(1 11) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 °C, while the crystallinity of AIN/ (0001) A12O3 samples improved from 700 to 850 °C. The optical absorption characteristics of the AIN/(0001) A12O3 films as grown by both deposition methods revealed a decrease in subbandgap absorption with increased substrate temperature.
Utilization of ß-Diketones for Etching and Cleaning of Metal Oxide and Sulfide Thin Films
Authors: Droes Steven R. , Jain A. , Kodas T.T. , Hampden-Smith M.J. , Muenchausen R. 
Published: March 2011

ABSTRACTWe are examining dry processes for wafer cleaning and producing patterned thin films of metal oxides. This research focuses on determining the kinetics and mechanism of the reaction between ß-diketones and selected metal oxides. Preliminary experiments indicated that CuO, MgO, PbO and ZnO all react readily with 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH). Thin films of CuO and MgO were fabricated via pulsed laser deposition, characterized by various analytical techniques such as Rutherford Backscattering Spectrometry and Scanning Electron Microscopy, etched using hfacH, and then further characterized. Etching rates for CuO and MgO were measured in order to develop a mechanistic understanding of the reaction.
The Diffusivity-Mobilitt Ratio Under Strong Magnetic Field in III-V Superlattices with Graded Structures
Authors: Ghatak Kamakhya P. , De Badal 
Published: March 2011

ABSTRACTIn this paper we have studied the Einstein relation for the diffusivity-mobility ratio in III-V superlattices with graded structures under magnetic quantization by formulating a new dispersion law. It is found, taking InAs/GaSb an example that the diffusivity mobility ratio increases in an oscillatory way with increasing carrier degeneracy as a consequence4SdH effect. The Einstein relation in IIIV superlattice is greater than that of the same for the constituent materials. Besides the theoretical results are in agreement with the suggested experimental method of determining the same ratio in degenerate materials having arbitrary dispersion laws.
A structure observation of GaAs micro crystal/Se-terminated GaAlAs interface for the quantum well box structure
Authors: Chikyow Toyohiro , Lijima Michihisa , Koguchi Nobuyuki 
Published: March 2011

ABSTRACTA selective growth of GaAs micro crystals was demonstrated on a Se-terminated GaAIAs surface by sequential supplies of Ga and As molecules for the quantum well box structure. After the growth, the surface consisted GaAs micro crystals with (111) facets and some Se clusters. The cross sectional investigations by the high resolution electron microscope revealed an epitaxial growth of GaAs micro crystals on the surface and a mixture of Ga2Se3 and A12Se3 layer formation at the interface of GaAs/Se-terminated GaAIAs. The selenidation process seems to be a reaction limited one. The Se cluster segregation could be avoided by selenidation in As molecule atmosphere.
Nitrogen-Atom Bonding at SiO2/Si Interfaces in Metalinsulator-Semiconductor (MIS) Stacked Gates Made by Integration of Plasma Assisted Oxidation-Deposition and Rapid Thermal Processing
Authors: Ma Y. , Yasuda T. , Lucovsky G. 
Published: March 2011

ABSTRACTSiO2 thin films were deposited by remote PECVD on Si surfaces exposed to species generated in O2/N2 and O2/NH3 plasmas. The surface chemistry was studied by Auger Electron Spectroscopy, AES, and the electrical properties of the SiO2/Si interface by high frequency and quasi-static Capacitance-Voltage, C-V, measurements. The AES results showed that Ccontamination was removed by exposure to both plasma-excited gas mixtures, but that N-atoms were incorporated into the SiO2 film, and Si-N bonds were formed at the SiO2/Si interface. C-V measurements indicated that the Si-N bonding structure, rather than the N-atom concentration, is critical in determining the interface electrical properties. The effects of Rapid Thermal Annealing, RTA, on the electrical properties of these SiO2/Si interfaces were also studied.
Rapid Thermal Annealing for Electrical Activation in the Fabrication of GaAs MESFET
Authors: Choi S.W. , Yang J.W. , Koak B.H. , Cho K.I. , Park H.M. 
Published: March 2011

ABSTRACTRapid thermal annealing (RTA) has been employed for the electrical activation of shallow n-channel layer by Si+ implantation in the fabrication of GaAs MESFET. To prevent considerable outdiffusion of gallium and arsenic from GaAs substrate during annealing, encapsulating layers such as SiNx and SiNx/SiO2 are deposited. The SiNx/SiO2 double dielectric encapsulant is shown to be more effective to improve the electrical activation. Depending on RTA temperature between 900 and 950°C, the maximum activation efficiency exhibits 77% at the implanted energy of 70 keV and the dose of 5×1012 cm−2. SIMS analyses show the reduction of the hydrogen contained in the silicon nitride and no outdiffusion of Ga and As during RTA. It also shows the sharp Si-profile after RTA at 950°C, 30 sec. The MESFET fabricated using activaton with RTA provides better transconductance than that with furnace-annealed activation.
A Dual-Function UHV-Compatible Chamber for i) Low-Temperature Plasma-Assisted Oxidation, and ii) High-Temperature Rapid Thermal Processing of Si-Based Dielectric Gate Heterostructures
Authors: Hattiangady S. , Xu X-L , Watkins M.J. , Hornung B. , Misra V. , Lucovsky G. , Wortman J.J. 
Published: March 2011

ABSTRACTA combination of i) low-temperature, 300-400°C, plasma-assisted oxidation to form the SiO2/Si interfaces, and ii) 800°C rapid thermal chemical vapor deposition, RTCVD, to deposit SiO2 thin films have been used to fabricate gate-oxide heterostructures. This sequence separates SiO2/Si interface formation by the oxidation process from the deposition of the bulk oxide layer by RTCVD. These two processes were performed in situ and sequentially in a single-chamber, ultraclean quartz reactor system. We have studied the chemistry of the interface formation process by Auger electron spectroscopy, AES, and the electrical properties of MOS devices with Al electrodes by C-V techniques.
Fabrication and Low Temperature Transport Studies of Sub-Micron, In-Plane Gated Fets Defined by Low Energy Ion Exposure
Authors: Andrews C.C. , Spencer G.F. , Li F. , Weichold M.H. , Kirk W.P. 
Published: March 2011

ABSTRACTNanoscale gated quantum wires in GaAs MODFET material with the conduction channel and gates in the plane of the 2DEG have been fabricated and studied. Electron beam lithography was used for mask definition followed by flood exposure to low energy argon ions (150 eV) for pattern transfer into the 2DEG. Compared to metal top-gate designs the in-plane design simplifies fabrication and reduces device capacitance, promising ultra-fast operation. This method of pattern transfer produced devices having channel-to-gate isolation of 1014 Ω and breakdown fields above 106 V/cm at 4.2 K. In addition to exhibiting standard FET characteristics, including gating to pinchoff, the devices showed significant negative differential resistance (NDR) in the saturation region.
Selective Area Epitaxy for Optoelectronic Devices
Authors: Temkin H. , Hamm R. A. , Feygenson A. , Cotta M. A. , Harriott L. R. , Ritter D. , Wang Y. L. 
Published: March 2011

ABSTRACTWe discuss the characteristics of MOMBE based selective area epitaxy useful in the preparation of optoelectronic devices. Selective area epitaxy, a process in which epitaxy is restricted only to the areas opened in a suitably prepared dielectric mask, offers a powerful method of preparing high performance devices, varying the thickness and composition of the grown layers simply by controlling the width of the open areas and monolithically integrating different device types on common substrates. Lasers, heterostructure bipolar transistors, and optoelectronic integrated circuits based on InGaAs/InP system and relying on selective area epitaxy are described.
Electronic Characterization of Mercuric Iodide Gamma Ray Spectrometers
Authors: Gerrish Vernon M. 
Published: March 2011

ABSTRACTDuring the past four years the yield of high-resolution mercuric iodide (HgI2) gamma ray spectrometers produced at EG&G/EM has increased dramatically. Data are presented which demonstrate a strong correlation between starting material and spectrometer performance. Improved spectrometer yields are attributed to the method of HgI2 synthesis and to material purification procedures. Data are also presented which show that spectrometer performance is correlated with hole mobility-lifetime products. In addition, the measurement of Schottky barrier heights on HgI2 spectrometers has been performed using I-V curves and the photoelectric method. Barrier heights near 1.10 eV have been obtained using various contacts and contact deposition methods. These data suggest the pinning of the Fermi level at midgap at the HgI2 surface, probably due to surface states formed prior to contact deposition.
A Study of Dark Currents on Various Modified Surfaces of Mercuric Iodide Single Crystals
Authors: Jayatirtha H. N. , Azoulay M. , George M.A. , Burger A. 
Published: March 2011

ABSTRACTThe surface modifications that occur on °-mercuric iodide surfaces during the fabrication process are crucial for the development of a low noise, high resolution X-ray spectrometer. In this study, we discuss the effects of surface treatments on the dark currents and the results are correlated with surface morphology studies that were carried out by the atomic force microscopy (AFM) technique.
CdTe detectors responses to pulsed X-rays : comparison of different materials
Authors: Verger L. , Cuzin M. , Glasser F. , Lajzerowicz J. , Mathy F. , Rustique J. 
Published: March 2011

ABSTRACTThe goal of this work is to compare and analyze the transient responses to X-ray pulses of different cadmium telluride detectors:- CdTe: Cl grown by the vertical Bridgman method (B.).- CdTe: Cl grown by the Travelling Heater Method (T.H.M.).- Cd0,8 Zn0,2 Te grown by the High Pressure Bridgman method (H.P.B.).Photoconductive detectors were subjected to very short (20 ns) 100 keV X-ray pulses and short (4 µs) 2 MeV pulses. The transient response of the photoconductors CdTe: Cl and CdZnTe under high X-ray energy beam were characterized in terms of sensitivity, linearity and dynamic range vs different parameters such as bias voltage and X-ray beam fluence. Bridgman and T.H.M. detectors show similar behaviors while H.P.B. detectors which are highly resistance show shorter transient behavior after the 20 ns pulses irradiations and larger afterglow after the 4 µs pulses irradiations.
HgCdTe MBE Technology : A Focus On Chemical Doping
Authors: Wu Owen K. 
Published: March 2011

ABSTRACTHgCdTe MBE technology is becoming a mature growth technology for infrared focal plane array applications. The ability to dope HgCdTe with In(n-type) and As(p-type) dopants in-situ provides greater flexibilities for fabricating heterojunction devices. In this paper, we will first discuss the current status of HgCdTe MBE growth and then focus on the key results in the control of In(n-type) doping, various approaches and breakthroughs in the growth of As(p-type) doped HgCdTe and issues related to doping such as memory effects and dopants activation. In addition, device results from double layer heterojunction structure(DLHJ) will be briefly discussed.
Crystallographic and Metallurgical Characterization of Radiation Detector Grade Cadmium Telluride Materials
Authors: Johnson C.J. , Eissler E.E. , Cameron S.E. , Kong Y. , Fan S. , Jovanovic S. , Lynn K.G. 
Published: March 2011

ABSTRACTRadiation detector grade CdTe crystals are characterized by several crystallographic and metallurgical techniques including infrared microscopy, dislocation etch pitting and X-ray diffraction. Results are presented for 50 detectors fabricated from an ingot produced by the high pressure Bridgman method. Data on the temperature dependence of leakage current and pulse height analysis are presented, along with measurements of room temperature charge transport properties. Attempts to relate crystal structure to detector performance will be discussed.
Performance Characteristics of Cdte Gamma-Ray Spectrometers
Authors: Squillante Michael R. , Cole Herbert , Waer Peter , Entine Gerald 
Published: March 2011

ABSTRACTThe use of cadmium telluride (CdTe) semiconductor nuclear detectors is continuing to expand into new areas because of their unique properties which include room temperature operation and high detection efficiency. In addition, they remain the material of choice in many critical applications such as nuclear medicine and power plant monitoring because of their reputation for reliability and long term stability1. CdTe is by far the most developed of the compound semiconductors used in nuclear detector applications and it offers a number of significant benefits to researchers, clinicians and engineers who have special requirements relating to size, sensitivity and operating temperature.Recently, there have been improvements in the growth of the crystalline material and in the fabrication procedures which have resulted in better performance and in the ability to produce arrays. This article describes the physical and electronic properties of CdTe nuclear detectors, discusses how the crystal growth and device fabrication procedures can affect these properties, and compares the performance to CdZnTe detectors.
Junction Field Effect Transistor X-RAY Detectors
Authors: Lund J.C. , Olschner F. , Rehn L. 
Published: March 2011

ABSTRACTWe describe the theory of operation, design, and estimated performance of an n-channel JFET designed to be operated as a detector in an X-ray spectrometer system. We estimate that a room temperature (300 K) JFET detector can be built with performance comparable to a small area, cryogenically cooled Si(Li) detector.
A Low Noise Silicon Detector Preamplifier System for Room Temperature X-Ray Spectroscopy
Authors: Bertuccio G. , Pullia A. 
Published: March 2011

ABSTRACTThe design and performances of a system for high resolution X-ray spectroscopy are presented. The detector is a low capacitance diode built on high resistivity silicon. The signal preamplification is made by means of an ultra-low noise charge amplifier of new conception. Presently the system exhibits an equivalent noise charge of 61 r.m.s. electrons at 297 K and 32 r.m.s. electrons at 223 K. It is shown how an improvement down to 30 r.m.s. electrons at room temperature is expected employing an integrated transistor on the detector chip.
Growth of Single Crystals of Mercuric Iodide on the Ground and in Space
Authors: van den Berg L. 
Published: March 2011

ABSTRACTA short review will be given of the methods by which mercuric iodide is prepared and purified to obtain material suitable for the growth of single crystals. The method used in our laboratory to grow single crystals up to 1,000 grams in weight from the vapor will be discussed. The effects of gravity on the growth process will be described.A crystal growth system suitable for operation in the reduced gravity environment of space was designed, and crystal growth experiments were performed during the flights of Spacelab 3 (April 1985) and the International Microgravity Laboratory (IML-1) (January 1992). The structural quality and electronic properties of the ground-based and spacegrown crystals were compared, and the results will be presented.
Mercuric Iodide X- and Gamma-Ray Deteciors for Space Applications
Authors: Iwanczyk Jan S. 
Published: March 2011

ABSTRACTRecently, substantial progress has been made in the development of HgI2 detectors and associated electronics for space instrumentation. The many technical challenges in the instrument development involving spectroscopy performance, power consumption, weight, size, operation over wide ranges of temperature and ambient gas pressure, and others have been overcome. Descriptions of instrumentation under development such as: x-ray and alpha backscattering spectrometer, scanning electron microscope and particle analyzer, Mössbauer spectrometer, and gamma-ray spectrometer are given.