bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Characterization of Ti3PSe4 Single Crystals
Authors: Singh N. B. , Hopkins R. H. , Mazelsky R. , Gottlieb M. 
Published: March 2011

ABSTRACTGood quality single crystals of Ti3PSe4 were grown from the melt by the Bridgman technique following improvements in the method of purifying the parent components, and optimization of growth parameters. Crack-free crystals 8 cm in length and 17 mm in diameter were produced.The quality of the crystals was evaluated by optical transmittance and metallographic techniques. In the range 0.7 to 14 μm the optical transmittance shows elimination of absorption bands exhibited in crystals grown without special purification steps. Etchpit studies showed that the crystals were free from inclusions and lamellar twins and that they show a uniform cross sectional etch pit density.
HgCdTe Versus Hgznte: Electronic Properties and Vacancy Formation Energies
Authors: Berding M. A. , Chen A.-B. , Sher A. 
Published: March 2011

ABSTRACTThe alloy variation of the band gap and the electron and hole effective masses have been calculated for HgCdTe and HgZnTe. Band-gap bowing is larger in HgZnTe than in HgCdTe because of the larger bond length mismatch of HgTe and ZnTe; electron and hole effective masses are found to be comparable for the two alloys for a given band gap. We have calculated the electron mobility in both alloys with contributions from phonon, impurity, and alloy scattering. Contributions to the E1 line width due to alloy and impurity scattering in Hg0.7Cd0.3Te have been calculated. Results of calculations of the vacancy formation energies in HgTe, ZnTe, and CdTe are discussed.
Photochemical Processes in Photo-Assisted Epitaxy of CdxHg 1-xTe
Authors: Irvine S J C , Mullin J B , Blackmore G W , Dosser O D , Hill H 
Published: March 2011

ABSTRACTMechanisms for the low temperature photo-dissociation of alkyl precursors for the epitaxial growth of CdxHg1-xTe (CMT) are discussed. The roles of vapour and surface nucleation are considered in the light of the free radical model which also can provide methods for controlling the vapour phase photochemistry. Higher quality CMT has been grown at 250 °C by using dimethyl mercury as a source of free methyl radicals. Problems encountered in reducing growth temperature for multilayer epitaxy are considered for CdTe and HgTe and conditions established for epitaxial growth at 200°C.The roles of alkyl concentration, substrate temperature, UV intensity and free radical concentration are explored. Results on the first reported growth of CdTe deposition using a cw UV laser source are compared with the arc lamp grown layers.
Characterization of Infrared Materials by X-Ray Diffraction Techniques
Authors: Takei W. J. , Doyle N. J. 
Published: March 2011

ABSTRACTX-ray diffraction techniques have proved invaluable in the characterization of infrared materials, particularly those prepared by thin film deposition techniques such as molecular beam epitaxy, MBE. The techniques are sufficiently sensitive and rapid to provide the information feedback required for efficient optimization of the growth process. They are nondestructive and permit the correlation with results on the same sample obtained by other characterization techniques such as those being described at this Symposium. Depending on the development status of the growth technology, the information to be acquired includes presence of twinning, quality, and type of epitaxial orientation, strains, and compositional variations. A critical issue in the application of these materials in detector arrays is the question of uniformity control, both laterally and in depth. The techniques to be described include not only modern x-ray topographic and multiple crystal diffractometric techniques but particularly for the early stages of growth process development, classical photographic ones such as the oscillation and Weissenberg methods. Examples of these various aspects are presented with emphasis placed on the characterization involved in MBE growth of HgCdTe films.
Atomic Structure of HgTe and CdTe Epitaxial Layers Grown by MBE on GaAs Substrates
Authors: Ponce F. A. , Anderson G. B. , Ballingall J. M. 
Published: March 2011

ABSTRACTUsing high resolution transmission electron microscopy (HRTEM) it is possible to directly image the projected structure of semiconductors with point resolutions at the atomic level. This technique has been applied to the study of interface and defect structures associated with molecular beam epitaxial (MBE) growth of HgCdTe layers on GaAs substrates. The structure of the CdTe/GaAs interfaces is described for (100) and (111) epitaxy. From the atomic structure, a model for the early stages of epitaxial growth is presented. The structure of HgTe-CdTe superlattices is discussed from the HRTEM point of view.
Dynamical X-ray Rocking curve Simulations of InGaAsP/InP Double Heterostruciures using Abeles' Matrix Method
Authors: Macrander A. T. , Glasgow B. M. , Minami E. R. , Karlicek R. F. , Mitcham D. L. , Riggs V. G. , Berreman D. W. , Johnston W. D. 
Published: March 2011

ABSTRACTSimulated rocking curves for a light-emitting diode structure are presented. Results for a structure containing uniform layers are compared to rocking curve data for a wafer grown by vapor phase epitaxy (VPE), and we conclude from the comparison that the VPE wafer closely approached the hypothetical ideal assumed in the simulations. Simulations illustrating difficulties in analyses and the effects of a graded active layer are also presented.
Deep Level Defects in CdTe
Authors: Leigh V. B. , Kremer R. E. 
Published: March 2011

ABSTRACTWe have used two complementary techniques to study deep trapping levels in CdTe single crystals. Samples of undoped, semi-insulating material and p-type material doped with phosphorus or cesium have been examined using transient spectroscopic techniques. Both capacitance transients (DLTS) and photocurrent transients (PITS) have been measured. The DLTS measurements showed several trapping levels in all of the specimens, while the PITS data usually revealed only a single level.
Development of HgCdTe for LWIR Imagers
Authors: Schmit Joseph L. 
Published: March 2011

ABSTRACTThis paper provides a historical perspective on the emergency of HgCdTe as the material of choice for long wavelength infrared (LWIR) imagers. The need for devices which see room temperature objects through the atmospheric window actually drove the development of this material. The lack of elemental or compound semiconductors having the desired wavelength response forced the choice of the alloy semiconductor, HgCdTe. The development of this material in several countries and companies beginning in the late 1950's is traced. The crystal growth methods used to grow HgCdTe have included melt growth techniques such as Bridgman, zone-melting, quench-anneal and slushgrowth. The solution growth techniques include growth from HgTe-rich, Te-rich and Hg-rich solutions. Vapor phase growth has included evaporation, sputtering, molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). No perfect method has yet been developed, but several have provided material for the large area arrays needed for modern imagers.
Low Temperature Photoluminescence Study of Doped CdTe and CdMnte Films Grown by Photoassisted Molecular Beam Epitaxy
Authors: Giles N. C. , Bicknell R. N. , Schetzina J. F. 
Published: March 2011

ABSTRACTN-type and p-type (100) CdTe films have been grown on (100) CdTe substrates by photoassisted molecular beam epitaxy, using indium and antimony as n-type and p-type dopants, respectively. The application of this growth technique to substitutionally dope another II-VI material is demonstrated by the successful n-type doping of (100) CdMnTe films with indium. Modulationdoped superlattices consisting of barrier layers of CdMnTe:In alternating with CdTe have also been grown. The point defect nature of these in situ doped films and multilayers is studied with low temperature (1.6–5 K) photoluminescence and excitation photoluminescence measurements. The introduction of the dopant atoms using this new growth technique produces immediate changes in the photoluminescence spectra of the epilayers. Photoluminescence studies of the superlattices show the effects of quantum well confinement and band filling due to free carriers.
Effects of Boron Implantation on Silicon Dioxide Passivated HgCdTe
Authors: Bowman R. C. , Marks J. , Downing R. G. , Knudsen J. F. , To G. A. 
Published: March 2011

ABSTRACTThe influence of boron ion implants on the optical and physical properties of photochemically deposited SiO2 films on HgO 7 CdO 3Te and silicon has been investigated. The distributions of the boron atoms between the SiO2 film and substrate have been determined by a nondestructive neutron depth profiling method. The implants produce an apparent densification of the SiO2 films, which is accompanied by an increase in refractive index and changes in the infrared vibrational spectra for these films.
Epitaxial Semiconductor Structures for the Infrared: Where Are We Now?
Authors: Panish Morton B. 
Published: March 2011

EXTENDED ABSTRACTThe use of epitaxial structures for the generation, detection, and modulation of light has had as its strongest driving force the development of fiber optic communications systems. Partly for that reason, the semiconductor materials systems that can be most readily optimized for wavelengths (800-1600nm) transmittable through state-of-the-art optical fibers, have been the most well developed. It also appears that the communications community has been most fortunate in that the semiconductor systems required, although far more difficult to deal with than Si, are relatively benign compared to those that operate at significantly shorter or longer wavelengths. Two developments that are now more than 15 years old initiated the extensive studies of compound semiconductor epitaxial structures that are now so important. These were the introduction of the heterostructure concept in the study of injection lasers and light emitting diodes (1), and the realization that lattice matched isoelectronic epitaxial layers, consisting in part of solid solutions between the binary compounds, would permit such structures to be grown.
Liquid-Phase Epitaxy of Hg1−xCdxTe from Hg Solution: A Route to Infrared Detector Structures
Authors: Tung Tse , Kalisher M. H. , Stevens A. P. , Herning P. E. 
Published: March 2011

ABSTRACTOver the past few years, liquid-phase epitaxy (LPE) has become an established growth technique for the synthesis of HgCdTe. This paper reviews one of the most successful LPE technologies developed for HgCdTe, specifically, “infinite-melt” vertical LPE (VLPE) from Hg-rich solutions.Despite the very high Hg vapor pressure (> 10 atm) and the extremely low solubility of Cd in the Hg solution (< 10−3 mol%), this approach was believed to offer the best long-term prospect for growth of HgCdTe suitable for various device structures. Since the initial demonstration of LPE growth of HgCdTe layers from Hg solution in experiments conducted at SBRC in 1978, the VLPE technology has advanced to the point where epitaxial HgCdTe can now be grown for photoconductive (PC) and photovoltaic (PV) as well as monolithic metal-insulator-semiconductor (MIS) and high-frequency laser-detector devices with state-of-the-art performance in the entire 2–12 μm spectral region.A historical perspective and the current status of VLPE technology are reported. Particular emphasis is placed on the important role of the ther-modynamic parameters (phase diagram) and on control of stoichiometry (defect chemistry) and impurity doping (distribution coefficient) for growth of HgCdTe layers from Hg solution. Critical material characteristics, such as transport properties, minority-carrier lifetime, morphology and crystal structure, are also discussed. Finally, a comparison with the LPE technol-ogy using Te solutions, which has been the mainstay of the remainder of the IR community, is presented.
Hg1−x−yCdxZnyTe: Growth, Properties and Potential for Infrared Detector Applications
Authors: Kaiser Debra L. , Becla Piotr 
Published: March 2011

ABSTRACTClose-spaced isothermal vapor phase epitaxy (VPE) was used to grow quaternary Hg1−x−yCdxZnyTe epillayers on Cd1−zZnzTe substrates. Composition, resistivity, and carrier concentration depth profiles were determined in the epilayers. p-n junctions were produced from material with appropriate properties using the Hg diffusion method. The junctions showed excellent I-V characteristics and high spectral detectivities.
InAsSbBi and InSbBi: Potential Material Systems for Infrared Detection
Authors: Bedair S. M. , Humphreys T. P. , Chaing P. K. , Katsuyama T. 
Published: March 2011

ABSTRACTInSb1−x Bix (0.01 < × < 0.14) and InAsSbBi quaternary alloys are potentially attractive materials for the development of semiconductor infrared detectors covering the 8–14 μm range [1,2,3].We report for the first time, MOCVD growth of InSo1−x Bix (0.01 < × < 0.14) and InAs1−x−y Sbx Biy with 0.5 < × < 0.7 and 0.01 < y < 0.04 on both GaAs and InSb substrates using AsH3, TMSb, TEI and TMBi. Electrical measurements of the undoped InSo0.99 Bi0.01 shows a background carrier concentration of approximately 1016/cm3 and a room temperature mobility of 20,215 cm2/V.sec. To-date, these are the best reported electrical measurements for this ternary alloy.The formation of a secondary Bi phase and single crystal growth of metallic bismuth-antimony at the surface of InSo1−x Bix which results in deterioration of morphology with increasing values of x is also investigated. A wide range of analytic techniques, including SEM, EDX, electron microprobe and AES have been employed in our surface analysis.
Preparation and Applications of Lead Chalcogenide Diode Lasers
Authors: Partin Dale L. 
Published: March 2011

ABSTRACTLead chalcogenide diode lasers are useful for spectroscopic and fiber optics applications in the mid-infrared (2.5-30 μm) wavelength range. These devices have previously required cryogenic cooling (<100 K) for CW operation. This limitation has been overcome through the use of a new, lattice-matched alloy system, Pb1-xEuxSeyTe1-y as well as the introduction of advanced, quantum well active region device structures grown by molecular beam epitaxy (MBE). Operating temperatures have been increased to 175 K CW (at 4.4 μm) and to 270 K pulsed (at 3.9 μm). Thermal leakage currents out of the device active region appear to be limiting device performance. This has led to the study of band offsets in PbEuSeTe/PbTe heterojunctions as well as to exploration of alternative high energy band gap alloys of PbTe with Ge, Yb, Ca, Sr, and Ba. The status of this work and examples of ultrahigh resolution studies done with these tunable laser sources will be included.
Epitaxial IV-VI Semiconductor Films
Authors: Chu T. K. , Martinez A. 
Published: March 2011

ABSTRACTEpitaxial films of IV-VI semiconductors and their alloys form the basis of an infrared detector technology that offers advantages in material stability as well as spectral versatility. These films are prepared by epitaxial hot-wall techniques and their material properties are essentially the same as those of bulk crystals. Because of their stability, multilayer growths of the materials can be achieved in a straight-forward manner. To date, multi-color detectors and small scale two-color detector arrays have been demonstrated successfully. A brief review of the growth method and the growth characteristics is given. Recent advances in superlattice research, especially those of interest to electro-optical devices, will be discussed. These include persistent photoconductivity and sub-bandgap optical transition.
Molecular Dynamics Studies of Semiconductor Thin Films and Interfaces
Authors: Grabow Marcia H. , Gilmer George H. 
Published: March 2011

ABSTRACTThe structure and stability of thin epitaxial films have been investigated using molecular dynamics computer simulations. One issue of interest is the stability of a smooth film relative to 3-dimensional clusters. The simulation results show that the uniform film is never the lowest energy state for a system with finite misfit. However, the uniform film, produced in a layer-by-layer growth mode, can persist in a metastable state at substantial misfits, e.g. 10% at 1/2 the melting point. This is a result of the large nucleation barrier to the formation of clusters.The second issue is the quality of the interface between the film and the substrate. At equilibrium, the critical thickness for the introduction of misfit dislocations is larger for films on the diamond cubic (100) substrate than on the (111), and differs from predictions based on continuum mechanics. We find that coherent films remain in metastable equilibrium far beyond the critical misfit calculated for full equilibrium, because a large free energy barrier inhibits the introduction of misfit dislocations.
Atomic Structures of Silicon Surfaces and Silicon-Silicide Interfaces
Authors: Liu H. M. , Tsong T. T. 
Published: March 2011

ABSTRACTAtomically resolved and well ordered field ion images of silicon surfaces have been obtained for the first time when a carefully cleaned Si tip is annealed to 700 to 800°C for several minutes. Well ordered atomic structures develop on high index planes such as the (130), (135), (124), (234), (123), (113), (115) and (320). Some of them develop the (1×1) structure while others are reconstructed. Two structures coexist for the (130) plane. Twodimensional defects can be seen and their density is surprisingly high. We have also studied formation of thin layers of silicide on silicon surfaces.
GaAs – on – Si Epitaxy: Results for Coverage of ∼ 1 Monolayer
Authors: Bringans R. D. , Olmstead M. A. , Uhrberg R. I. G. , Bachrach R. Z. 
Published: March 2011

ABSTRACTCore level spectroscopy measurements have been made on Si substrates with coverages of around one monolayer of As, Ga and GaAs. The interfaces were formed on on-axis Si(100) and Si(111) substrates using molecular beam epitaxy. Results are also presented for an arsenic monolayer on a single-domain Si(100) surface prepared by cutting the crystal off-axis by 4 degrees. The strong bonding between As monolayers and the surface of the substrate causes the GaAs to begin to form islands at average coverages of less than one monolayer. The surface between the islands is found to be terminated by a single atomic layer of As. Use of a Ga predeposition technique shows evidence of reducing the tendancy towards island formation.
Investigations of Microstructural Changes in Nickel Thin Films on Ionimplanted Silicon by Cross-Sectional Transmission Electron Microscopy with Intermittent Annealings in N2 Ambient
Authors: Lu S. W. , Nieh C. W. , Chang C. S. , Chen L. J. 
Published: March 2011

ABSTRACTThe feasibility of studying dynamical changes in nickel thin films on ion-implanted silicon thin films by cross-sectional transmission electron microscopy (XTEM) with intermittent annealings in N2 ambient up to 850 °C is demonstrated. Interactions of nickel thin films with oxidation induced stacking faults, fluorine bubbles and process-induced defects in ion implanted silicon are provided as examples. The technique may be applied to clarify a number of important issues encountered in the study of the reactions and diffusion of thin films and obtain informations otherwise unattainable.
The Kinetics of Ni-Al Spinel Growth Using Rutherford Backscattering Spectroscopy
Authors: Simpson Y. Kouh , Colgan E. G. , Carter C. B. 
Published: March 2011

ABSTRACTUsing a planar thin-film specimen geometry, the growth kinetics of the spinel in NiOAl2O3 system has been studied with Rutherford backscattering spectroscopy. A thin-layer of Ni film is deposited by the electron-beam deposition technique onto single-crystal alumina substrates of different orientations including, (0001), {1120}, {1102} and {1100}. The subsequent heat-treatment in air then converts the Ni to NiO, thus producing a uniform layer of NiO with good adhesion between the NiO and the alumina. The kinetics of the Ni-Al spinel growth has been found to be different for different single-crystal substrate orientations. The kinetics behavior follows a parabolic growth-rate law for each orientation but shows a different reaction-rate constant. X-ray diffraction and transmission electron microscopy have been used as complementary techniques to confirm the phases that form at each stage of the heat treatment and the corresponding microstructures of the thin-film layers respectively.
Optical and Electrical Characterizations of AlxGa1−xSb
Authors: Kitamura N. , Yamamoto H. , Higuchi K. , Maeda Y. , Usami A. , Wada T. 
Published: March 2011

ABSTRACTThe LPE grown AlxGa1−xSb was investigated by means of TEM, a carrier profiler and PL. The TEM image showed the dissociated 60° dislocations and Lomer-Cottrell sessile dislocation formed by the reaction of two dissociated 60° dislocations on different {111} planes. The EPMA measurement showed that Sb concentrations at the dislocation were lower than the stoichiometric composition. The epi-layer grown at 400°C had a relatively uniform carrier concentration of ∼7×1016cm−3. The PL spectra showed five emission peaks in 0≦×≦0.29. One shallow acceptor level and two native defect levels were introduced to interpret these PL emissions. The shallow acceptor level of Ev+∼30meV may be due to the defect of VGaGaSb. The native defects introduce two levels of EΓ1 - ∼90meV and EL1 - ∼160meV. The defect levels may be related to the complex defect of the Sb vacancy.
Control of the Initial Stage of Ge Overgrowth on CaF2/Si Structures by Electron Beam Exposure
Authors: Kanemaru S. , Ishiwara H. , Furukawa S. 
Published: March 2011

ABSTRACTThe initial stage of Ge overgrowth on CaF2/Si structures was controlled by electron beam (e-beam) exposure through a room-temperature-deposited thin Ge layer on CaF2. It was found that the island growth of Ge was prevented in the e-beam exposed region and the crystalline quality and the surface flat-ness of the Ge film were much improved. From several experimental results, a growth model that e-beam dissociates the surface F atoms of CaF2 and improves the wettability between Ge and CaF2 is proposed.
Surface Stress Tensor Mediation of the Ledge Nucleation/Growth Process with the Surface Reconstruction Process in GaAs
Authors: Choi D. K. , Halicioglu T. , Tiller W. A. 
Published: March 2011

ABSTRACTA new GaAs semiempirical potential energy function which utilizes both two-body and three-body contributions has been used to evaluate the surface energy and surface stress tensor for the (111) and (001)(As-terminated) surfaces as well as for ledges on the (001) surface. Both surface and ledge reconstruction patterns appear to be driven by stress tensor considerations and a long range ledge-ledge interaction arises via the stress tensor. The impact of this finding on two dimensional cluster formation and nucleation at the growing surface is very substantial.
The Role of Misfit Dislocation During Epitaxial Growth
Authors: Cherns D. 
Published: March 2011

ABSTRACTThe theory of Frank and van der Merwe (FM) in 1949 showed that a minimum energy criterion could explain the pseudomorphic growth of a deposit on a substrate of different lattice spacing and the subsequent relief of strain by misfit dislocations as the deposit thickness increases. Although the “equilibrium” theory is qualitatively correct, account must be taken of actual dislocation sources, which may be complex, and which may be more or less efficient for misfit relief than predicted by the FM model. Moreover, misfit dislocation sources may determine the morphology of the growing film, the interface topology and even the atomic structure of the deposit/substrate interface. These various roles of misfit dislocations are reviewed here with examples from work on metal/metal, semiconductor/semiconductor and metal/semiconductor systems.