bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitaxial Growth of Rare Earth Silicides on (111)Si
Authors: Lee T. L. , Sue W. D. , Lin J. H. , Luo C. H. , Chen L. J. 
Published: March 2011

AbstractEpitaxial YSi2-x, TbSi2-x, and ErSi2-x. have been grown on (111)Si by solid phase epitaxy in ultrahigh vacuum deposited rare earth (RE) metal thin films on silicon. The evolution of vacancy ordering and defect structure in epitaxial RE silicide thin films on (111)Si have been studied by both conventional and high resolution transmission electron microscopy.Additional superlattice spots located at 1/3 <2110> in the diffraction pattern of RESi2-x, are attributed to the formation of ordered vacancy in the Si sublattice planes. The splitting of extra diffraction spots is correlated to the formation of an out-of--step structure. Streakings of the split diffraction spots in the diffraction pattern are attributed to the presence of an out-of-step structure with a range of M values. For YSi2-x and ErSi2-x, the M was found to settle down to a constant value after high temperature and/or long time annealing. For TbSi2-x, M is equal to 5 throughout the annealing.Planar defects in RESi2-x films were analyzed to be stacking faults on {1010} planes with 1/6<1213> displacement vectors. The size and density of stacking faults were found to increase and decrease, respectively, with annealing temperature and/or annealing time.
X-Ray Spectroscopic Studies of Organo-Metallic Vapor Phase Epitaxial Growth
Authors: Brennant S. , Fuosst P. H. , Kisker D. W. , Lamelast F. J. , Imperatori P. , Stephenson G. B. 
Published: March 2011

AbstractChemical Vapor Deposition often occurs under conditions unsuitable for simultaneous monitoring using electron-based structural probes. This is due to the near-atmospheric pressure which exists during growth. While some work has been performed using optical probes, the typically high temperatures in the reactor vessel and the vastly longer wavelength of visible light versus the features being studied has hampered its utility as a structural probe. Over the past several years x-rays from synchrotron storage rings have been used to study the surface structure of growing materials. These studies have been primarily scattering studies. In this paper we explore the use of x-ray spectroscopic studies for the analysis of film growth. We have focused on three areas: the measurement of reactor vessel profiles using x-ray fluorescence; The measurement of gas-phase Extended X-ray Absorption Fine Structure (EXAFS), and the measurement of EXAFS of adsorbed species on the substrates.
Significance of a Nucleation Layer in Inhibiting Interfacial Pitting in InAs Films Grown by Two-Step MOVCD on (100) Inp Substrates
Authors: Ballal A. K. , Salamanca-Riba L. , Partin D. L. 
Published: March 2011

AbstractIn this paper, we study the significance of a low temperature nucleation layer and its role in inhibiting interfacial pitting vapor deposition. Transmission electron microscopy and scanning electron microscopy studies show that severe interfacial pitting occurs for thin nucleation layers of average thicknesses of 200Å and 400Å. For these average nucleation layer thicknesses we have found that the InAs islands do not cover the entire substrate surface during the low temperature deposition. Hence, when the film is heated to a higher temperature for the growth of the remainder of the film severe pitting at the heterointerface is produced. The thermal etchpits are sources of threading dislocations, which propagate to the surface of the film. For thicker nucleation layers we observe no interfacial pitting. Our studies show that there is an optimum nucleation layer thickness for which high quality InAs films with reduced threading dislocation densities and relatively high electron mobilities are obtained. Both electrical and structural studies suggest that ∼ 800Å is an optimum thickness of the low temperature nucleation layer.
Kinetic Control of CaF2 on Si(111) Growth Morphology
Authors: Denlinger J. D. , Rotenberg Eli , Hessingert U. , Leskovar M. , Olmstead Marjorie A. 
Published: March 2011

AbstractThin (0.5 to 8 triple layer) CaF2 on Si(111) films were grown using molecular beam epitaxy (MBE) and characterized using an in situ combination of x-ray photoelectron spectroscopy (XPS) and componentresolved x-ray photoelectron diffraction (XPD). We identified surface, bulk-like, and interface F and Ca core-level shifts and used the XPS shifts and XPD modulations to identify the growth modes as a function of the kinetic parameters of CaF2 flux and Si temperature. We identify 3 distinct regimes: (i) for high temperatures and flux we find a complete reacted F-Ca-Si layer, overlaid by 2 layer high islands which coalesce, followed by layer-by-layer growth, (ii) for high temperature and low flux, we find the reacted F-Ca-Si layer to be partially covered with thick islands, and (iii) for low temperatures we find an incompletely occupied F-Ca-Si layer followed by layer-by-layer growth. In all cases we find the buried interface to be structurally identical to the unburied F-Ca-Si layer
Stm Imaging of Adsorbed Trimethylgallium on GaAs(001)-(2×4)
Authors: Avery A. R. , Mayne A. J. , Goringe C. M. , Owen J. H. G. , Smith C. W. , Schweitzer M. O. , Jones T. S. , Briggs G. A. D. , Weinberg W. H. 
Published: March 2011

AbstractScanning tunnelling microscopy (STM) has been used to image the adsorption of trimethylgallium (TMGa) on GaAs(001)-(2×4) surfaces prepared in situ by molecular beam epitaxy (MBE). Filled states images of the clean surface are dominated by (2×4) unit cells containing only two As dimers. Upon exposure of this surface to TMGa at room temperature, bright oval-shaped features are observed which are centred on the arsenic dimers of the unit cell. These arise from tunnelling from Ga-C bonds of the adsorbed molecules. At low coverages, preferential adsorption on unit cells adjacent to occupied sites along the [110] direction is observed. A detailed statistical analysis of a large number of adsorption sites shows that there is an increased probability of about 24% for adsorption next to a (2×4) unit cell which is occupied relative to an unoccupied one.
Steps of Surface Etching and Carbon Deposition on the Graphite Basal Plane
Authors: Chu Xi , Chan Vincent , Schmidt Lanny D. 
Published: March 2011

AbstractThe reactions of O2, H2O, CO2, NO2, NO, and N2O with single crystal graphite between 400 and 700°C have been studied by STM to obtain quantitative kinetics by measuring the number and size of monolayer pits on the basal plane versus temperature and time. At low temperature the reaction initiates exclusively from the point defects on the basal plane to form monolayer pits. The shape of the monolayer pits vary from nearly triangular to hexagonal to circular depending on the rate of the reaction and the reacting gases. The sizes of the monolayer pits grow linearly with reacting time. The monolayer reaction rates follow the order of RNO2 > RN2O > RNO > RO2 > RH2O > RCO2. The activation energies for reactions with O2, H2O, NO2, NO, and N2O, are determined to be 127, 205, 60, 89, and 74 kJ/mol respectively.Carbon deposition from hydrocarbons onto surfaces of single crystal graphite has been examined to study the fundamental steps of chemical vapor deposition. Uniform monolayer pits on graphite surface were first produced by reactive etching of freshly cleaved single crystal of graphite in oxygen and carbon was then made to deposit exclusively on these defects in the basal plane. Carbon vapor deposition forms unique structures around the monolayer steps. By measuring the sizes of structures on steps in various gases versus temperature and pressure, the kinetics of hydrocarbon decomposition and the role of surface diffusion can be determined.
Kinetics of Epitaxial Layer Growth from Silane on (100) Silicon
Authors: Greve D. W. 
Published: March 2011

AbstractLow temperature growth of silicon from silane is required in devices such as germanium- silicon HBTs and multiple quantum well structures for infrared detectors. Understanding the silicon growth kinetics is an important step in developing a complete model for incorporation of other species such as germanium, boron, and phosphorus. In this paper, we show that a wide range of recent data can be well explained by a model which includes the effect of hydrogen carrier gas and is based on a simple two- step reaction sequence for silane decomposition. Gas phase reactions and gas phase transport limits appear unimportant at least up to 1 Torr total pressure.
Photoluminescence Studies of a Quantum Well Modulated by Faceting on Gaas (110) Surfaces
Authors: Tomiya S. , Reaves C. M. , Krishnamurthy M. , Wassermeier M. , Bimberg D. , Petroff P. M. , DenBaars S. P. 
Published: March 2011

AbstractStep bunching during epitaxial growth results in the transformation of a vicinal surface into a periodic array of micro-facets. Molecular beam epitaxial growth on the vicinal GaAs (110) surface exhibits this phenomenon which has primarily been characterized by electron microscopy. GaAs quantum wells with AlAs barriers were grown on GaAs(110) substrates vicinal 0.5-2· towards [010]. The faceting on the vicinal surface creates two distinct quantum well thicknesses. While most of the quantum well is 96Å thick, it broadens at the faceted regions. This thickness modulation produces two distinct luminescence peaks. By using temperature dependent photoluminescence, we have observed trends in exciton mobility. The exciton mobility decreases at low temperatures for the 1.0° and 2.0° samples, indicating a scattering mechanism. We will discuss interface roughness and other sources of scattering.
Interfacial Atomic Structure in Heteroepitaxial β-SiC on TiC Substrates
Authors: Chien Fen-Ren , Nutt S. R. , Carulli J. , Buchan N. , Yoo W. S. , Mailloux P. M. 
Published: March 2011

AbstractThin epitaxial films of β-SiC were grown on (100), (111) and (112) TiC substrates and the interfaces were characterized by HREM. The (111) interface was abrupt and atomically flat, while the (112) interface was composed of {111} facets and steps. The (100) orientation did not result in epitaxial growth of SiC, a phenomenon attributed to the poor match of atomic positions in SiC and TiC on the (100) plane, although the lattice parameters are relatively close. A model for the atomic structure of the stable (111) interface is proposed based on comparison with HREM images of the interfaces.
Kinetic Roughening in Epitaxial Growth of Bcc (110) Films
Authors: Fritzsche Helmut , Gradmann Ulrich 
Published: March 2011

AbstractFor the epitaxial growth of bcc(110) metals on bcc(110) metal substrates, there is a general tendency for roughening by formation of quasi-periodic ridges along [001], with up-and-down staircases in the [110] direction. It can be detected by high angular resolution Spot Profile Analysis (SPA)-LEED, as has been done previously by Hahn et al. for the case of W(110) on W(110). We found this kinetic facetting for Fe(110) on Fe(110), where it can be described by the model of layer restricted diffusion (LRD) epitaxy. We observed the same phenomenon for Fe(110) on W(110), Fe(110) on Cr(110), Cr(110) on W(110) and Cr(110) on Fe(110). In this paper, we present data for Fe(110) on Cr(110). The change between sharp single spots for in-phase energies to double spots for out-of-phase energies documents the staircase facet structure; it can be used to measure a vertical strain in the films.
The Role of Vertical Exchange in the Growth of GaAs/AlAs Lateral and Vertical Superlattices
Authors: Lorke Axel , Krishnamurthy Mohan , Petroff Pierre M. 
Published: March 2011

AbstractWe report on the formation of lateral superlattices in short period vertical GaAs/AlAs superlattices. To explain the observed self-organized phase separation, we propose a model of vertical intermixing, driven by the exchange of Ga on the surface with impinging Al atoms. The model correctly describes the formation of lateral superlattices for both integer and fractional monolayer deposition. It also predicts a far-reaching intermixing at GaAs-AlAs interfaces. Insitu RHEED studies of the initial growth stage of both GaAs-AlAs and AlAs-GaAs interfaces support the assumption of an asymmetric exchange at the growing surface and confirm the longrange Ga migration predicted by the model.
Irradiation Effects of Ar-Cluster Ion Beams on Si Surfaces
Authors: Takaoka G. H. , Sugahara G. , Hummel R. E. , Northby J. A. , Sosnowski M. , Yamada I. 
Published: March 2011

ABSTRACTThe effects of energetic Ar cluster ion impacts on Si(111) surfaces have been studied for cluster energies up to l5keV. The mean cluster size was about 1000 atoms, and the smaller sizes could be systematically excluded. Si samples irradiated at different cluster ion energies were analyzed by RBS, ellipsometry, and differential reflectometry. Implantation of Ar in samples irradiated with cluster ions was found by RBS to be detectable, but very small in comparison with samples irradiated with monomer ions of the same energy. The thickness of the damage layer as measured by both ellipsometry and differential reflectometry was also much smaller in the cluster ion irradiated samples.
Investigation of Damage Induced by Low Energy Focused Ion Beam Irradiation in GaAs
Authors: Kosugi Toshihiko , Yuba Yoshihiko , Gamo Kenji 
Published: March 2011

ABSTRACTDefects induced by Ga focused ion beam (FIB) irradiation at an energy between 0.1 and IkeV have been characterized by means of deep level transient spectroscopy (DLTS) and related capacitance measurements. Seven different kinds of defect centers were resolved and two centers at 0.33 and O.56eV below the conduction band were dominant in the 100eV Ga implanted sample at doses up to 1015/cm2. Induced defect centers were observed to distribute over the region far beyond the theoretical ion range, which resulted from defect migration during the irradiation. Low energy irradiation induced defects were readily annealed out during low temperature heat treatment in contrast to those induced by high energy irradiations.
The Influence of an In-Situ Electric Field on H+ and He+ Implantation Induced Defects in Silicon
Authors: Ravi J. , Erokhin Yu. , Koveshnikov S. , Rozgonyi G.A. , White C.W. 
Published: March 2011

ABSTRACTThe influence of in-situ electronic perturbations on defect generation during 150 keV proton implantation into biased silicon p-n junctions has been investigated. The concentration and spatial distribution of the deep traps were characterized using a modification of the double corelation deep level transient spectroscopy technique (D-DLTS). With the in-situ electric field applied, a decrease in concentration of vacancy-related, as well as H-related, traps was observed. 500 keV He+ implantation was also performed to supplement the above studies and to differentiate any passivation effects due to hydrogen. A model based on the charge states of hydrogen and vacancies was used to explain the observed behaviour.
Dislocation Loops in Spinel Crystals Irradiated Successively with Deep and Shallow Ion Implants
Authors: Ai Rebecca X. , Bordes Nicole , Cooper Elizabeth A. , Sickafus Kurt E. , Ewing Rodney C. , Nastasi Michael 
Published: March 2011

ABSTRACTThis study examines the influence of microstructural defects on irradiation damage accumulation in the oxide spinel. Single crystals of the compound MgAl2O4 with surface normal [111] were irradiated under cryogenic temperature (100°K) either with 50 keV Ne ions (fluence 5.0 × 1012/cm2), 400 keV Ne ions (fluence 6.7 × 1013cm2) or successively with 400 keV Ne ions followed by 50 keV Ne ions. The projected range of 50 keV Ne ions in spinel is ~50 nm (“shallow”) while the projected range of 400 keV Ne ions is ~ 500 nm (“deep”). Transmission electron microscopy (TEM) was used to examine dislocation loops/ defect clusters formed by the implantation process. Measurements of the dislocation loop size were made using weak-beam imaging technique on cross-sectional TEM ion-implanted specimens. Defect clusters were observed in both deep and shallow implanted specimens, while dislocation loops were observed in the shallow implanted sample that was previously irradiated by 400 keV Ne ions. Cluster size was seen to increase for shallow implants in crystals irradiated with a deep implant (size ~8.5 nm) as compared to crystals treated only to a shallow implant (size ~3.1 nm).
Layer by Layer Amorphization in Si: Temperature, Ion Mass and Flux Effects
Authors: Battaglia A. , Romano G. , Campisano S.U. 
Published: March 2011

ABSTRACTThe layer-by-layer amorphization process is explored in a temperature range in which the kinetics of crystallization can be neglected. It has been found that the pure amorphization rate increases exponentially as the substrate temperature is decreased with an apparent activation energy of 0.48 eV. Moreover the rate increases with both the ion flux and the energy deposited into elastic collisions. A phenomenological model is proposed to explain the experimental results.
Microstructures of Si Surface Layers Implanted with Cu
Authors: Follstaedt David M. , Myers Samuel M. 
Published: March 2011

ABSTRACTThe microstructures of Si ion-implanted with Cu have been characterized by TEM after annealing. For 1.2 at.%, the Cu is trapped at planar defects, but for 10 at.%, η-Cu3Si forms, allowing Cu to diffuse at its equilibrium solubility. These observations allow proper evaluation of the binding energies of Cu to previously formed internal cavities (2.2 eV) and η-Cu3Si (1.7 eV). The η-Cu3Si in the 10 at.% layer catalyzes oxidation of the Si. The microstructures also indicate that Si implanted with ~2 at.% Cu reforms epitaxially with embedded defects after 8 hr. at 700°C, but for ~10 at.% Cu, epitaxy is not recovered after 6 hours at 600ºC.
Ion Beam Induced Structural and Electrical Modifications in Crystalline and Amorphous Silicon
Authors: Coffa S. , Battaglia A. , Priolo F. 
Published: March 2011

ABSTRACTThe mechanisms of defect accumulation and dynamic annealing in ion-implanted crystalline and amorphous Si are elucidated by performing conductivity and Raman spec-trascopy measurements in-situ during ion irradiation. In amorphous Si the entire gamut of defect structures has been characterized by analyzing the annealing kinetics from 77 K to ~ 800 K both during and after irradiation. Moreover the modifications in the electronic properties of crystalline Si produced by ion-irradiation have been investigated. The use of in-situ techniques in combination with transmission electron microscopy and deep-level transient spectroscopy allowed us to demonstrate the correlation between structural and electrical defects produced by ion-irradiation in Si.
Barrier Effect of Retrograde Well Against Ion-Induced-Charge Carriers
Authors: Sayama Hirokazu , Kishimoto Takehisa , Takai Mikio , Kimura Hiroshi , Ohno Yoshikazu , Sonoda Ken-Ichiro , Kotani Norihiko , Satoh Shin-Ichi 
Published: March 2011

ABSTRACTThe charge collection efficiency of a diode with a retrograde well was estimated using focused ion beam irradiation at 400 keV and 2 MeV. The retrograde well was found to effectively suppress a collection of charge carriers created by energetic particles. The charge collection efficiency of the diode with the retrograde well was ~ 25 % lower than that with the conventional well when 400 keV ~ 2 MeV protons were irradiated normal to diodes. This result was in good agreement with device simulation.
Ion Beam Processing of InGaAsP
Authors: Pearton S.J. , Abernathy C.R. , Wisk P.W. , REN F. 
Published: March 2011

ABSTRACTThe activation kinetics of Si+ and Be+ ions implanted into InGaAsP (λ = 1.3 µm) grown by MOMBE were studied over a variety of doses (5 × 1012 - 5 × 1014 cm-2), annealing times (3-60 sec) and temperatures (575-750°C). Maximum doping concentrations of ~2 × 1019 cm-3 were obtained for both Si+ and Be+, with activation energies for electrical activation of 0.58 eV and 0.39 eV, respectively. Multiple energy F+ or H+ implants can be used to produce high resistance layers for isolation purposes - maximum sheet resistances of ~8 × 106 Ω/□or ~106 Ω/□ for initially p+or n+ InGaAsP, respectively, were obtained for F+ implants followed by annealing near 450 °C. Smooth, anisotropic dry etching of the InGaAsP was obtained with low pressure CH4/H2/Ar discharges with the etch rates being independent of conductivity type or doping levels.
Formation of Shallow Energy Levels in Mn+ Implanted GaAs with Extremely Low Background Impurity Concentration
Authors: Shen Honglie , Makita Yunosuke , Yamada Akimasa , Niki Shigeru , Iida Tsutomu , Shibata Hajime , Fons Paul , Obara Akira 
Published: March 2011

ABSTRACTManganese ions implantation into ultrapure GaAs layers grown by molecular beam epitaxy were investigated by photoluminescence technique systematically in a wide range of manganese concentration up to 1×1020cm-3. Five shallow emission bands denoted by (Mn°, X), “G”, “G' “ “H” and (D, A)2 are formed in the implanted layers in addition to the well known Mn impurity related emission at ~880nm. With increasing manganese concentration to 1×1019cm-3, “G” exhibits no energy shift, suggesting that “G” is different from the behavior of [g-g] emission that is commonly formed in shallow acceptor (such as C) incorporated ultrapure GaAs. (Mn°, X), “G” and “G' “ present no energy shift with increasing excitation intensity, while “H” and (D, A)2 indicate peak energy shift greatly showing typical donor-acceptor pair characteristics. “G” and (Mn°, X) are found to hold similar radiative origin which is different from “G”. Temperature dependence measurement reveals that emission “G” has a thermal activation energy of 5.4meV.
Ion Beam Surface Modification for Achieving Rectification in Gold-Aluminum Nitride-Silicon Junctions
Authors: Stacy T. , Liaw B. Y. , Khan A. H. , Zhao G. , Charlson E. M. , Charlson E. J. , Meese J. M. , Prelas M. , Wragg J. L. , Chamberlain J. E. , White H. W. 
Published: March 2011

ABSTRACTLow energy ion bombardment has been utilized to fabricate rectifying contacts on aluminum nitride grown on single crystal silicon substrates. Bombardment of aluminum nitride with methane was followed by sputter deposition of gold contacts. To our knowledge, this is the first report of rectifying contact formation on aluminum nitride. Scanning electron micrographs show that the initially ordered aluminum nitride surface is significantly altered with low energy methane ion beam exposure. Electrical measurements made on samples which had been partially masked during implantation indicate that rectification is a result of the ion bombardment.
Nonlinear Optical Materials Synthesized by Ion Implantation: Metal Quantum Dots in Transparent Dielectrics
Authors: Haglund Richard F. , Osborne D. H. , Yang LI , Magruder R. H. , White C. W. , Zuhr R. A. 
Published: March 2011

ABSTRACTComposites consisting of nanometer-size metal clusters embedded in a host dielectric can be synthesized by implanting metal ions in either glassy or crystalline substrates. The size and size distributions of the nanoclusters can be controlled by varying the parameters either of the ion-implantation process or subsequent annealing. The nonlinear optical response of these quantum-dot composites can be modeled as that of independent electrons confined to a spherical potential well; experimental data on relaxation times compares favorably with this simple picture. Optical figures-of-merit of these materials suggest potential for applications in nonlinear waveguide devices, particularly since ion implantation is compatible with device-fabrication processes. The basic features of these materials are illustrated from experiments on Cu and Pb clusters in silica.