bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-Situ Dry Etching of InP Using Phosphorus Tri-Chloride and Re-Growth Inside a Chemical Beam Epitaxial Growth Chamber
Authors: Kapre K M. , Tsang W. T. , Sciortino P. F. 
Published: March 2011

ABSTRACTWe have extended the capability and versatility of a chemical beam epitaxial (CBE) system by demonstrating reactive chemical beam etching (RCBE) of InP using phosphorus tri chloride (PCl3)as the gaseous etching beam injected directly into the growth chamber. This permits instant switching from etching to growth (and vice versa) in the same run for the first time in CBE. We investigated RCBE of InP at various substrate temperatures between 400 °C and 580°C, under different PCl3 fluences, and etching conditions. Excellent surface morphology was obtained at high temperatures (> 530°C - 570°C) and under an etching rate of < 6 Å/sec. We also found that upon addition of trimethylindium flow equivalent to a growth rate of 1 Å/sec during RCBE a dramatic improvement in surface morphology was obtained even at a high net etching rate of 10 Å/sec. The surface morphology obtained under such conditions is indistinguishable from that of the original substrate surface. Using Si02 as a mask, in-situ etching of laser mesas followed immediately by regrowth of blocking layers with excellent wetting characteristics was obtained.
Modification of AmBv Semiconductor Layers by Ion Implantation
Authors: Wesch W. 
Published: March 2011

ABSTRACTThe damage production in GaAs, InAs, GaP and InP implanted with different mass ions in the temperature region 80K to 450K has been investigated by means of the RBS/channeling technique at 300K and 100K as well as by optical transmission and reflection measurements. The influence of the implantation parameters on the damage production as well as the differences observed for the various materials are discussed. Further, results concerning the electrical activation after rapid thermal annealing of GaAs and InP implanted at different temperatures are presented.
Defects and Diffusion in Si+ Implanted GaAs
Authors: Jones K.S. , Robinson H.G. , Haynes T.E. , Deal M.D. , Lee C.C. , Allen E.L. 
Published: March 2011

ABSTRACTThe effect of extended defects on the diffusion of ion implanted species is an area of concern in the development of process simulators for GaAs. This study explores the effect of type I extended defects including voids and dislocation loops on the diffusion of Si implanted into GaAs. <100> Semi-insulating GaAs wafers were implanted with 1 × 1014/cm2 Si+ at implant temperatures between -51°C and 80°C and at energies ranging from 20 keV to 200 keV. SIMS results show that the diffusivity of Si decreases with both increasing implant temperature and increasing implant energy. At the same time extrinsic dislocation loop concentrations also increased. For the implant conditions studied, no voids were observed. The diffusion results can only be reconciled with the TEM results if the dislocation loops are behaving in a reactive rather than proactive manner. In other words, the changes in vacancy concentration that are affecting the diffusivity are also affecting the loop concentration. This model is supported by evidence that Si diffusivity is enhanced over the same time interval the dislocation loops are dissolving which is consistent with the loops having a reactive role. It remains unclear whether the existence of loops significantly affects the total concentration of vacancies and thus diffusion by acting as a competing sink.
Rapid Thermal Annealing of InP Implanted with Group IV Eleients
Authors: Ridgway M.C. , Kringhoj P 
Published: March 2011

ABSTRACTElectrical activation and carrier mobility have been studied as a function of ion dose and annealing temperature for InP implanted with Group IV elements (Si, Ge and Sn). In general, electrical activation increases with decreasing ion dose and/or increasing annealing temperature. Si and Sn exhibit comparable activation and mobility, superior to that of Ge, over the ion dose and temperature range examined. The relative influences of implantation-induced non-stoichiometry and the amphoteric behaviour of the group IV elements have been investigated. For the latter, the amphoteric behavior of Ge > Si > Sn.
Optical Characterization of 100 eV C+ Ion Doped GaAs
Authors: Iida Tsutomu , Makita Yunosuke , Kimura Shinji , Winter Stefan , Yamada Akimasa , Shibata Hajime , Obara Akira , Niki Shigeru , Fons Paul , Tsai Yushin , Uekusa Shin-ichiro 
Published: March 2011

ABSTRACTLow energy (100 eV) impinging of carbon (C+) ions was made during molecular beam epitaxy (MBE) of GaAs using combined ion beam and molecular beam epitaxy (CIBMBE) technologies for the growth temperature ( Tg ) between 500 °C and 590 °C. 2 K photoluminescence (PL), Raman scattering and Hall effect measurements were made for the samples. In the PL spectra two specific emissions, “g” and [g-g], were observed which are closely associated with acceptor impurities. PL and Hall effect measurements indicate that C atoms were very efficiently introduced during MBE growth by CIBMBE and were both optically and electrically well activated as acceptors even at Tg=500 °C. The results reveal that defect-free impurity doping without subsequent annealing can be achieved by CIBMBE method.
Pseudomorphic HEMT Devices for Microwave and Millimeter Wave Applications
Authors: Wu C.S. , Lan G.L. , Pao C.K. , Bar S.X. , Hu M. 
Published: March 2011

ABSTRACTPseudomorphic HEMT (PHEMT) devices have demonstrated superior performance at microwave and millimeter wave frequency ranges. They exhibit multi-functional characteristics such as high power, high efficiency and low noise over a broad frequency range (C-band through W-band). Because of their important, broad range of applications, the microwave industry has recently begun developing the PHEMT manufacturing technology in order to cope with the increasing demand for PHEMT insertion into microwave products. In this paper we will discuss the advantages of using PHEMT devices for microwave and millimeter wave applications and provide an overview of the published state-ofthe-art performance of PHEMT devices and monolithic microwave integrated circuits (MMICs) at microwave and millimeter wave frequencies. We will also present recent progress in Hughes PHEMT technology development including device epitaxial design and process enhancements. Finally, we will present recent data on PHEMT reliability.
Gas-Phase Generation of Nanometer-Sized Metal Particles for Fabrication of Zero-Dimensional Quantum Structures
Authors: Pluym Tammy C. , Kodas T.T. , Wang L.M. , Wiedensohler A. , Hansson H.C. , Maximov L. , Samuelson L. 
Published: March 2011

ABSTRACTNanometer-sized particles of Mo, Ta, Nb, and Pd were formed by gas-phase reactions of metal halides and β-diketonates in the presence of hydrogen. Particle diameters ranged from 5-100 nm depending on the reaction temperature (500-950 βC) and precursor characteristics. Gasphase particle concentrations reached 108/cm3. These particles are suitable as etching masks on semiconductor substrates for generation of zero-dimensional quantum structures.
Effect of Doping on the Growth of InGaP by Low Pressure Metalorganic Chemical Vapor Deposition
Authors: Wu C.H. , Feng M.S. , Wu C.C. 
Published: March 2011

ABSTRACTA study of the effect of dopant incorporation on the growth of InGaP by low pressure metalorganic chemical vapor deposition has been performed, in which diethylzinc (DEZn) and H2Se are used as p and n-type doping sources, respectively. The enhancement of interdiffusion, i.e., the disordering of a InGaP layer has been observed due to the introduction of Zn into the growth layer, as indicated by the decrease of intensity of the extra spots on TEM diffraction results. In addition, streaky and wavy diffraction pattern for Se-doped layer reveals the formation of anti-phase domains on a growth layer. According to PL measurement, the emission energy of the grown layer is a function of doping concentration, for which the energy shift as high as 141 meV has been obtained at heavily zinc doping concentration. Therefore, by varying the doping concentration, energy shift can be controlled, providing a potential for its application in optical devices.
Determination of the Valence Band Offset in GaAs/(Ga,Al)As Superlattices by Hot Electron Excitation Spectroscopy
Authors: Weinert H. , Zukauskas A. , Latinis V. , Stepankevicius V. 
Published: March 2011

ABSTRACTA GaAs/Ga1−xA1xAs-superlattice was investigated using quasi-cw PL measurements at T=2 K. The relevant sample parameters were determined by X-ray diffraction: barrier thickness - 5 nm, qw-thickness - 5 nm, x = 0.41. A series of PL-spectra at medium, but constant excitation intensity for different excitation energy (from 1.64 eV to 2.1 eV) was measured. From the high-energy slope of the PL-spectra the electron-temperature Te was determined. A clearly structured dependence of Te on hvexc (excitation energy) was found. We assumed the pronounced structures of the Te - hvexc - hvexc - “spectrum” to be the onset-energies of new, for lower excitation energies not possible relaxation processes. Calculating the excess energy for each kind of carriers (heavy and light holes and electrons) separately, we found δEv=( 0.18 ± 0.05) ∆Eg for the investigated sample. Using this new experimental method one also is able to obtain the energies of higher electronic states (for example Γ → L -transitions) of GaAs/(Ga,Al)Assuperlattices.
DX Centers in AlGaAs and Pressurised GaAs
Authors: Anand S. , Subramanian S. , Arora B. M. , Lu Y. C. , Bauser E. 
Published: March 2011

ABSTRACTIn this paper, we present results of our investigations on some aspects of the DX centers. It is shown from the low temperature Hall mobility measurements that the charge state of the DX center is neutral supporting the positive U model for the DX center. Hall and DLTS measurements on Al-rich Al0.8Ga0.2As:Te sample show a reversal in the ordering of the energies of the hydrogenic and deep states of the Te donor, with the DX state lying higher than the X valley related effective mass state. Thermal emission properties of the pressure induced DX states of Ge and Se donors in neutron transmutation doped (NTD) GaAs are discussed.
Low Dislocation-Density and Vacancy-Rich Glassy-Pinning Quasi GaAs Crystal by Liquid-Encapsulated Czochralski Growth
Authors: Saito Yasutuki , Fujii Takashi 
Published: March 2011

ABSTRACTNot all threshold voltage (Vth) scattering of Si-implanted metal-semiconductor field- effect- transistors (MESFETs) on low dislocation density and semi-insulating (S.I.) liquid- glass encapsulation Czochralski (LEC) GaAs crystals grown at relatively high pull-speed were small. By comparison with the Lang x-ray topographs of the wafers, it was found that x-ray topograph contrast variations reflected on the films did not correspond with Vth variations of the wafers at all. Especially, in low dislocation density regions, which are in white regions on the films of the x-ray topographs, very large Vth turbulences were observed. We believe that dislocation-less in LEC GaAs crystals causes large Vth turbulences of Si-implanted MESFETs and that frozen cell-lattice-structure large turbulences by pinning centers associated with vacancies like glass cause large Vth turbulences.
Electronic and Optical Properties of HgI2
Authors: Chang Yia-Chung , Sim Hock-Kee , James R. B. 
Published: March 2011

ABSTRACTWe present theoretical studies of electronic structures, optical responses, and phonon modes of undoped HgI2 in its red tetragonal form. The electronic band structure is studied via an empirical nonlocal pseudopotential model, including the spin-orbit interaction. The electron and hole effective masses, optical matrix elements for interband transitions, and complex dielectric function are computed. Excitonic effects on the absorption coefficient near the fundamental band gap are included within the effectivemass approximation. The resulting absorption spectra and their polarization dependence are compared with experiment with favorable agreement. The phonon modes of HgI2 are studied with a microscopic model and a good fit to the neutron scattering data is obtained.
Electrical Properties in Cvd Diamond Films
Authors: Zhao S. , Gan K.K. , Kagan H. , Kass R. , Malchow R. , Morrow F. , Palmer W. , White C. , Pan L.S. , Han S. , Kania D. , Plano M. , Landstrass M. , Lee M. , Kim S. , Sannes F. , Schnetzer S. , Stone R. , Thomson G. , Sugimoto Y. , Fry A. , Kanda S. , Olsen S. 
Published: March 2011

ABSTRACTThe electrical properties associated with carrier mobility, μ, and lifetime, τ, have been investigated for the chemical vapor deposited (CVD) diamond films using charged particle-induced conductivity and time resolved transient photo-induced conductivity. The collection distance, d, the average distance which electron and hole depart when driven by an applied electric field E, was measured by both methods. The collection distance is related to the carrier mobility and lifetime by d = μEτ Our measurements show that the collection distance increases linearly with sample thickness for CVD diamond films. The collection distance at the growth side of the CVD diamond film is comparable to that of single crystal natural type IIa diamond; at the substrate side of the film, the collection distance is near zero. No saturation of the collection distance is observed for film thickness up to 500 microns.
Radiation Dosimetry Via the Radio-Photoluminescence of Synthetic Diamond
Authors: Keddy Rex J. , Nam Tom L. , Araikum Shawn 
Published: March 2011

ABSTRACTA method of radiation dosimetry based upon the radiophotoluminescence (RPL) of synthetic diamond crystals is presented. When the RPL is generated by a stimulation wavelength of 296 nm a linear response vs radiation dose of up to 20 kGy can be obtained with selected crystals. The response is very dependent on the chemistry of the synthesized specimen.
Electrical Mobility and Carrier Lifetime in Single-Crystal, Isotopically Pure Type IIa Synthetic Diamond
Authors: Pan L. S. , Han S. , Kania D. R. , Banholzer W. 
Published: March 2011

ABSTRACTSingle-crystal type IIa diamonds were synthesized by applying high temperatures (1200°;C) and high pressures (52000 atm) to powdered polycrystalline diamond grown using conventional CVD techniques. These samples were isotopically pure, consisting of approximately 99.93% 12C, compared to roughly 98.96% in natural IIa diamonds. In addition, the dislocation density of the synthetic samples is significantly lower than in natural IIa diamonds, as indicated by birefringence measurements. Electrical properties of these samples were measured using transient photoconductivity, where a 3 ps pulse of ultraviolet light (6.1 eV) was used to excite free electron-hole pairs. Compared to natural IIa diamonds, the lifetime at low fields (200 V/cm) and low excitation densities (1015 cm-3) in the synthetic sample was significantly longer (1 ns in the synthetic sample vs. 200 to 300 ps in natural diamond). At higher fields, a much longer decay component, exceeding 10 ns, was observed in the synthetic sample. Combined electron and hole mobilities were around 2500 cm2/V-s in the synthetic diamond, compared to 3000 to 4000 cm2/V-s in the best natural samples. At a field of 2 kV/cm, the drift distance in the synthetic sample was over 50 μm, considerably longer than that of natural diamond (10 μm). This is due primarily to the much longer carrier lifetimes. The longer lifetimes in the synthetic sample demonstrate that the properties of the best natural diamonds can be exceeded and are encouraging for the development of sensitive diamond radiation detectors. These longer lifetimes are likely due to the higher quality and lower defect density in the synthetic samples, rather than the isotopic purity.
Fundamentals of Semiconductor Detectors for Ionizing Radiation
Authors: Knoll G.F. , Mcgregor D.S. 
Published: March 2011

ABSTRACTThe modes of operation of semiconductor detectors are reviewed, together with the influence of charge carrier collection in developing a signal pulse for spectroscopic applications. Because of the importance of charge trapping in many semiconductors of interest in the fabrication of room temperature radiation detectors, the effects of incomplete charge collection are quantified. Calculated results are presented for the expected pulse height and energy resolution under a variety of charge collection conditions.
Sub-Nanosecond Detection of Heavy Ions Using Single-Crystal, Natural Type IIA Diamond
Authors: Han Sung , Prussin Stanley G. , Pan Lawrence S. , Lane Stephen M. , Kania Don R. , Wagner Ronald S. , Evans Caleb R. 
Published: March 2011

ABSTRACTThe sub-nanosecond electrical transients induced by 5-MeV He+ and 10-MeV Si3+ ions have been measured in single-crystal, natural type Ila diamonds. The detectors were fabricated into conductivity modulated devices and were incorporated into 50-Ω high bandwidth transmission line structures. The electrical signals were recorded with a system based on a 70 GHz random sampling oscilloscope with the total recording rise time of 18.6 ±:0.6 ps.Signal rise times are less than 70 ps and fall times are less than 200 ps for electric fields in the range 3.8x104 - 1×105 V/cm. The plasma time appears to play a key role in defining the initial stages of the charge transport because signal rise times are much greater than the recording system rise time, especially with the Si-ion excitation. Furthermore, incomplete charge collection is quite severe even at the highest applied electric fields due to the dominance of carrier trapping/recombination at the defect sites.
Band-Edge Photoresponse Characteristics of Diamond Msm's
Authors: Marchywka Mike , Binari Steven C. , Koolbeck Deborah A. , Moses Daniel 
Published: March 2011

ABSTRACTBand-edge photoresponse measurements on simple diamond metal-semiconductor-metal (MSM) devices can give information about the quality of the diamond material and its utility as a detector. We have fabricated several such devices on a variety of substrates and measured their response between 700 and 120nm with special emphasis around the band edge near 220nm. Steady state and transient response have been measured as a function of bias conditions. Transient response in this case refers to initial overshoot, undershoot, and increased dark current in response to a chopped vacuum ultraviolet (VUV) light signal for times on the order of seconds. We compare steady state quantum efficiency results to a simple model, discuss the characteristics of response versus applied voltage, and examine relationships between response and substrate properties.
Fast GaAs Photoconductor Responses to Subnanosecond Proton Pulses
Authors: Brullot B. , Galli R. , Lecat X. , Rubbelynck C. , Pochet T. 
Published: March 2011

ABSTRACTGaAs photoconductors -have been tailored to detect ultrafast proton pulses having energies ranging between 4 and 9 MeV. The sensitivity, the linearity and the speed of response of the devices are analyzed as a function of their neutron pre-irradiation treatment. The dependence of the sensitivity on the proton energy and the applied polarization is also studied. Finally, the experimental results are compared with a simple theoretical model.
Multi-Element Mercuric Iodide Detector Systems for X-Ray and Gamma-Ray Imaging
Authors: Patt Bradley E. 
Published: March 2011

ABSTRACTThe advancement of room-temperature mercuric iodide detector technology to the point of spectroscopy-grade energy resolution coupled with the advancement in long-term stability and the high efficiency of these detectors now make it's use in large scale array systems for x- and gamma-ray imaging applications viable. Camera design criterion differ depending upon the application. A HgI2 gamma-ray camera developed at EG&G Energy Measurements has been used for imaging with various apertures, and the energy dispersive imaging aspects have been examined. Concepts for applications such as medical diagnostic imaging and a satellite based telescopes for x- and gamma-ray mapping have been objectified.
Characterization of Growth Defects in ZnTe Single Crystals
Authors: Zhou W. , Wu J. , Dudley M. , Su C.H. , Volz M.P. , Gillies D.C. , Szofran F.R. , Lehoczky S.L. 
Published: March 2011

ABSTRACT(111) wafers sliced from a boule of ZnTe grown by horizontal physical vapor transport (PVT) have been characterized using synchrotron white beam X-ray topography. The growth axis was about 6° off [311]. The presence of dislocation slip bands, subgrain structures and [111] axis 180° rotational twins were revealed. The slip bands were observed to break up the ordered dislocation cell structures comprising the subgrain boundaries. The initiation of slip at regions of stress concentration at the junctions of subgrain boundaries and twin boundaries was observed. The asymmetric distribution of slip bands either side of the twinned region of crystal suggests that twin boundaries can act as barriers for slip. Several types of detailed twin boundary configuration were determined from the topographs. Using a combination of white beam X-ray topography and Nomarski interference microscopy, the three dimensional shapes of the twin boundaries were determined. Approximate atomic structures at these boundaries are presented.
An Array of CdTe Detectors for Imaging Applications
Authors: Eisen Y. , Polak E. 
Published: March 2011

ABSTRACTThe performance characteristics of a linear array composed of several hundred miniature spectroscopy grade CdTe detectors are described. The linear array is utilized in a X-ray security imaging system. It operates either in an energy dispersive mode to highlight certain atomic elements in the luggage or in a regular mode for obtaining only the transmission image of the luggage. The array functions in the photon counting mode and tolerates count rates as high as 106 counts/sec. The array has high quantum efficiency and good spatial resolution which result in excellent image quality. The dynamic range, the electronic noise, the energy resolution, the homogeneity of response among detectors and the image quality are presented.
Elemental Impurity Analysis of Mercuric Iodide by Icp/Ms
Authors: Cros Eilene S. , Mroz Eugene , Olivares José A. 
Published: March 2011

ABSTRACTA method has been developed to analyze mercuric iodide (HgI2) for elemental contamination using Inductively Coupled Plasma/Mass Spectroscopy (ICP/MS). This paper will discuss the ICP/MS method, the effectiveness of purification schemes for removing impurities from Hgl2, as well as preliminary correlations between HgI2 detectorperformance and elemental contamination levels.
A HgI2 Microstrip Detector Based on Resistive Charge Division Readout
Authors: Grassi D. , Murolo F. , Perillo E. , Spadaccini G. , Vigilante M. , Amann M. , Koebel J.M. , Siffert P. , Dusi W. 
Published: March 2011

ABSTRACTA HgI2 linear array detector with a surface resistive layer between the readout strips has been constructed with the aim of achieving the maximum possible active detection area and a spatial resolution of ≈ 50 µm, by using an analog readout of the strip outputs and a centroid finding algorithm.This device has been developed as a high efficiency position-sensitive detector for use in a Bragg X-ray spectrometer, designed for detecting X-ray photons with energies up to ≈ 30 keV.Calculations performed by taking into account the various sources of electronic noise have allowed the optimization of the interstrip distance and resistance.Fabrication techniques and preliminary results on energy and spatial resolution are reported and discussed.