bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Incorporation and Behavior of Oxygen in AlGaAs Grown by Mombe Using Trimethylamine Alane
Authors: Abernathy C. R. , Song J. , Hobson W. S. , Pearton S. J. , Ren F. , Bohling D. A. , Muhr G. T. 
Published: March 2011

ABSTRACTTrimethylamine alane (TMAAl) has been demonstrated to be a superior Al precursor for growth of AIGaAs by metal-organic molecular beam (MOMBE). TMAA1 reduces both carbon and oxygen contamination relative to the standard Al source, triethylaluminum (TEA1). However, AlGaAs grown with TMAAl still shows a residual oxygen background of ∼2 × 1018 cm−3 when used with triethylgallium (TEGa) and either As4 or ASH3. This background is independent of Al mole fraction and is due primarily to alkoxides in the TEGa. AIGaAs grown with TMAAl and elemental Ga contains oxygen at levels commonly obtained in MBE, −2 × 1017 cm-3. While an oxygen level of −2 × 1018 cm-3 is not desirable, we have found that most of this impurity is electrically inactive as evidenced by room temperature photoluminescence and n-type dopant activation. In light of this, we have assessed the applicability of AlGaAs grown with TMAAl to the fabrication of high-speed GaAs/AIGaAs devices. The source is found to be suitable for structures like the heterojunction bipolar transistor.
Analysis of the Physical and Chemical Factors Determining Compositional Variations in the MOCVD Growth of Indium Gallium Arsenide
Authors: Einset Erik O. , Jensen Klavs F. , Kuech Thomas F. 
Published: March 2011

ABSTRACTWe present an analysis of compositional variations in the growth of the compound semiconductor, InxGal-xAs, by metal organic chemical vapor deposition (MOCVD). A three dimensional transport model for fluid flow, heat, and mass transfer is solved using the finite element method. The Delta Lattice Parameter (DLP) model is used to describe the thermodynamics of the solid solution, and the Hertz-Langmuir equation is used to calculate the evaporation rate of indium from the growing crystal. Wall depletion is incorporated by allowing for explicit wall deposition of In vapor throughout the reactor.Comparison of model predictions with experimental observations by MOCVD of InGaAs in a horizontal reactor suggests that transport phenomena lead to composition variations across the substrate, and that solution thermodynamics have little effect on the InAs incorporation rate at a given deposition temperature. However, thermodynamic factors appear to influence the change in indium incorporation with growth temperature.
The Surface Chemistry of Si/Ge Deposition
Authors: Crowell John E. , Lu Guangquan , Ning Bob M. H. 
Published: March 2011

ABSTRACTReaction processes leading to the deposition of Si and Ge epilayers have been delineated using a combination of surface spectroscopies. The dissociative adsorption of disilane and digermane has been investigated on the Ge(111) surface using multiple internal reflection infrared spectroscopy (MIRIRS). Molecular adsorption of Si2H6 and Ge2H6 occurs for adsorption below 150K. Molecular and dissociative adsorption are competitive processes at 110-140K. Dissociative adsorption of Si2H6 and Ge2H6 occurs above 150K. Trihydride formation (SiH3 and GeH3) is favored near 150-200K, while Si-H and Ge-H bond scission becomes significant above 200K. Di- and trihydrides are dominant below 300K, while the monohydrides are most prevalent above 300K. Decomposition of all surface hydrides occurs by 600K. On the Si(100) surface, digermane adsorption leads to the deposition of a Ge overlayer. Hydrogen desorption from the Ge/Si(100) surface is strongly altered with respect to the clean Si surface. The observed desorption behavior has important consequence on the low temperature deposition of Sil-xGex by thermal CVD.
Surface Chemistry of Silicon and Germanium Treated with Hydrofluoric Acid Solutions: Slow Reactions of Process Residuals
Authors: Yota J. , Burrows V.A. 
Published: March 2011

ABSTRACTSolutions of hydrofluoric acid are used extensively in the processing of semiconductors, primarily in etching and in oxide stripping procedures. Such solutions are often buffered with ammonium fluoride to insure constant oxide stripping rates. Infrared spectroscopy of silicon and germanium surfaces treated with such solutions indicates that a thin film of ammonium salts will deposit on the materials unless they are immediately and very thoroughly rinsed following treatment. This thin film, comprised initially of ammonium bifluoride (NH4FHF), reacts with the semiconductor material to form ammonium fluoride (NH4F) as a reactive intermediate, and ammonium hexafluorometallate ((NH4)2 SiF6 or (NH4)2 GeF6). These reactions occur very slowly, over hours or days. They are apparently driven by favorable thermodynamics. This explanation is supported by the absence of comparable reactions using analogous chlorine-based solutions (HCI/NH4 CI). Aspects of the reaction mechanism for hexafluorometallate production is presented.
Chemically Assisted Ion Beam Etching of SiGe
Authors: Glembocki O.J. , Prokes S.M. , Stahlbush R.E. 
Published: March 2011

ABSTRACTChemically assisted ion beam etching (CAIBE) of Si1−Gex films is reported. Ar+ ion sputtering in the presence of Cl2 background gas has been used to etch epitaxial films of Si1−xGex, with x ranging between 0 and 0.5. It is found that Si1−xGex, sputters more rapidly than Si, but less than Ge. The use of C12 gas enhances the sputter rates of SiGe as in the case of Si. Analysis of the etch rates indicates that the etch rate increase is due to an enhancement of the sputtering process, rather than a chemical effect.
The Deposition of Aluminum and Aluminum Boride Thin Films by Aluminaborane Cluster Compounds
Authors: Glass John A. , Kher Shreyas , Hersee Stephen D. , Ramseyer G. , Spencer James T. 
Published: March 2011

ABSTRACTThe preparation of aluminum-containing thin film materials by MOCVD and MOMBE for use in III-V semiconductor materials, such as HEMT devices, is currently under active investigation. The preparation of uniform, conformal aluminum and boron containing thin film materials from the chemical vapor deposition (CVD) of aluminum borane cluster precursor compounds has been studied. A variety of substrates, deposition conditions and aluminaborane precursors have been explored and their effect on film composition, growth rate and thin film morphology has been investigated. The thermal depositions of aluminum and boron-containing thin films from aluminum borohydride, AI(BH4)3, on copper, SiO2 and GaAs are reported. Boron incorporation in the films vary depending on substrate temperature, aluminaborane flow and the presence or absence of a H2 carrier. These films have been characterized by SEM, AES and XES.
Morphology and Deposition Conditions of CVD Au Films
Authors: Holloway Karen , Zuhoski Steven P. , Reynolds Scott , Matuszewski Christine 
Published: March 2011

ABSTRACTThe chemical vapor deposition of Au films by thermal decomposition from an organometallic precursor [dimethyl 1,1,1,5,5,5-hexaflouro-2,3-pentanedionato Au (III)] has been investigated for application as a interconnection metallization. The morphology and feature fill properties of deposits obtained using H2 and N2 carrier gases and varying pressure and temperature conditions were observed by cross-section scanning and transmission electron microscopy (SEM and TEM). Line patterns etched in SiO2 with aspect ratios up to 1.5 filled with few or no voids at a growth temperature of 250°C. For films deposited in H2 the Au grain size is large (on the order of the feature size). In unetched areas, however, large (600 nm) triangular-shaped structures protrude from the deposit. TEM observation shows that these structures are single-crystal Au dendrites which contain a central twinned region. Au films grown at 275°C had poor hole fills with large, irregular voids. These films exhibited large protrusions which occluded the lines and halted growth in these areas. The deposit morphology suggests a low reaction probability except at preferred crystal sites.
The Deposition of Nickel Boride Thin Films by Borane and Metallaborane Cluster Compounds
Authors: Glass John A. , Kher Shreyas , Kim Yoon-Gi , Dowben P.A. , Spencer James T. 
Published: March 2011

ABSTRACTThe deposition of high purity and controlled stoichiometry metal boride thin-film materials has recently received considerable interest. Borane clusters and their corresponding metal complexes are currently being investigated in our laboratories for their utility as unique source materials for the formation of metallic boride thin films by MOCVD. Variable composition nickel boride thin films ranging from 0.1 micron to several microns have been prepared. These new materials have been characterized by SEM, AES and XES. The magnetic properties of these new films have been investigated with torque magnetometry and magneto-optic Kerr effect magnetometry.
Halogenation of Diamond (100) Using Atomic Beams
Authors: Freedman Andrew , Stinespring Charter D. 
Published: March 2011

ABSTRACTDiamond (100) substrates have been halogenated under ultrahigh vacuum conditions using atomic beams of chlorine and fluorine. X-ray photoelectron spectra of the resulting samples indicate that saturation levels of less than a monolayer occur for both species. The fluoride adlayer is stable up to 700 K and slowly desorbs at temperatures above this temperature. In contrast, the chlorine adlayer starts to desorb above 223 K, the lowest temperature sampled.
Characteristics of Oxide Layer Grown on Gallium Arsenide Using 2.8-eV Translational Energy Atomic Oxygen
Authors: Cross J.B. , Hoffbauer M.A. , Farr J.D. , Glembocki O.J. , Bermudez V.M. 
Published: March 2011

ABSTRACTOxide layers that are thick (>200 Å and uniform have been produced on GaAs (110) and (100) by reacting the substrate (Ts<160°C) with high translational energy (1-3 eV) neutral atomic oxygen at flux levels of∼50 monolayers/second. The Ga and As species are formed in their highest oxidation states, which implies formation of either Ga2O3 and As2O5 or GaAsO4. Raman spectroscopy indicates that there is no metallic (amorphous or crystalline) As in the oxide or at the interface between the oxide and substrate and that there is no appreciable oxidation induced disorder of the substrate as is seen in high temperature thermal oxidation processes.
Trimethylamine Gallane as a Precursor to Cubic Gallium Nitride and Gallium Arsenide. Metal Hydride Chemical Vapor Deposition
Authors: Gladfelter Wayne L. , Hwang Jen-Wei , Phillips Everett C. , Evans John F. , Hanson Scott A. , Jensen Klavs F. 
Published: March 2011

ABSTRACTCyclo-trigallazane, [H2GaNH2]3, is known to form bulk powders of the new cubic phase of gallium nitride upon pyrolysis. An explanation for this unusual example where the molecular structure of the precursor controls the crystal structure of the solid state product is presented. In a hot-wall atmospheric pressure chemical vapor deposition (CVD) reactor, arsine was found to react with TMAG to form films of polycrystalline GaAs which were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The growth rates for smooth films was 1-4 μm/h. In a low pressure CVD reactor, elemental arsenic vapor was also found to react with the TMAG to give GaAs thin films.
A Synchrotron Radiation Study of Nonlinear Diffusion in Cu-Au
Authors: Menon E. S. K. , Huang P. , Kraitchman M. , Hoyt J. J. , Chow P. , Fontaine D. De 
Published: March 2011

AbstractAlternate layers of pure copper and gold were vapor deposited on a sodium chloride substrate, the average concentration of the films being Cu-16at% Au and the layering periodicity (modulation wavelength) being 3.31 nm. The composition modulation gives rise to satellite diffraction peaks around the (200) Bragg reflections. Synchrotron radiation at SSRL was able to detect up to third order satellite intensity the evolution of which was measured as a function of annealing time at 515 K. Although the first order satellite intensity decayed as expected exponentially with time, intensities of both second and third order satellites decreased very rapidly at first, then increased before decaying exponentially. These results are in conformity with theoretical models of satellite evolution during annealing in a onedimensional modulated system governed by a nonlinear diffusion equation.
Kinetics of Surface Ordering on Au-Rich Cu3Au(001)
Authors: Rivers S. B. , Unertl W. N. , Hung H. H. , Liang K. S. 
Published: March 2011

Abstractwe report grazing-incidence x-ray scattering measurements of the order-disorder phase transition near a Au-rich Cu3Au (001) surface. The bulk transition temperature TB = 648 K is lower than for stoichiometric Cu3Au(001). Surface ordering persists above TB in a layer several monolayers thick up to Ts = 667 K. Kinetics of the ordering were studied by quenching from Ts + 9 K to final temperatures of TF = 661 K and 645 K. Short-range order is established in the bulk within the quench time and does not appear to change subsequently. The bulk short-range order differs from that reported for stoichiometric Cu3Au. For TB < TF = 661 K < TS, the (100) in-plane diffraction beam intensity grows approximately as t1/4 for t > 1000 s and the width continues to narrow. For TF = 645 K < TB, power law growth is not observed for the longest times studied. In both cases the growth is substantially slower than predicted.
Evidence of a Correlation Between the Transition Temperature for Ordering and the Activation Energy for Ordering Kinetics in Ni75Al25-xFex Superalloys
Authors: Kozubski R. , Soltys J. , Cadeville M.C. , Pierron-Bohhes V. 
Published: March 2011

AbstractKinetics of long-range ordering was studied in the alloys Ni75Al25-xFex by means of in situ resistometry. The alloys under consideration exhibit a dramatic decrease of the "order-disorder" transition temperature Ttr with increasing X. After the existing theoretical models, the activation energy of long-range ordering should depend on one hand on the energy of ordering - related to Ttr -, and on the other hand, on the current value of the LRO degree. The performed measurements yield an experimental evidence of the above relationships. In addition, a considerable effect of magnetic order on LRO kinetics has also been registered. The results are qualitatively discussed in terms of the model of LRO kinetics in L12 structure proposed by Schoijet and Girifalco.
Antiphase Domain Structures and Analytical Electron Microscopy of α-Bainite in a Cu-Zn-Al Alloy.
Authors: Hamada Y. , Wayman C.M. , Wu M.H. 
Published: March 2011

AbstractAntiphase domain (APD) structures and associated composition analyses of the α l-bainite which forms during isothermal heat-treatment of a Cu-26.7wt%Zn-4.0wt%Al alloy have been examined by TEM dark field imaging and energy dispersive X-ray microanalysis. At an early stage both nearest-neighbor (NN) and next-nearest-neigbor (NNN) APD structures of the β-parent phase are inherited by the α1-bainite having an M18R structure. The EDX analyses indicate that there is a difference in composition between the α 1-bainite and the β-parent phase at this stage in spite of the inheritence of both NN and NNN APD structures. Local depletion of Zn concentration at dislocations is also observed in the parent phase. With increasing aging time, the α 1-bainite grows in a manner that the NN APD structure still remains inherited but the NNN APB structure changes into a NNN disordered structure at outer regions of the plate. In addition, Zn and Al rich regions also form adjacent to the interface in the parent phase. The observed growth of APD structures in association with compositional analyses strongly suggest that the initial bainitic transformation is by a shear mechanism at solute depleted defects although subsequent plate growth is diffusion dominated.
Phase Formation, Kinetics and Microhardness of the Nitride Layer in Ion Nitrided 316L Stainless Steel
Authors: Blucher J.T. , Marchev K. , Gokhale S. , Giessen B.C. 
Published: March 2011

Abstract316 L stainless steel (nominally 18% Cr, 8% Ni, 2% Mo, 1% Mn, balance Fe) has been ion nitrided in a N2/H2 atmosphere. Studies of nitride layer depth, structure, composition and microhardness show uniform layer formation with a sharp layer-to-matrix interface and a hardness increase over the bulk value by 600%. The structures of the nitride layers vary with treatment temperature, falling into two regimes over the temperature range studied. Generally, parabolic layer growth was found, and the growth coefficients were determined at five temperatures.
Pressure-Enhanced Solid Phase Epitaxy: Implications for Point Defect Mechanisms
Authors: Lu Guo-Quan , Nygren Eric , Aziz Michael J. 
Published: March 2011

AbstractWe have measured the effects of hydrostatic pressure on the solid phase epitaxial growth (SPEG) rates of undoped Ge(100) and Si(100) into their respective self-implanted amorphous phases. We found that pressure enhances the growth process in both Si and Ge, with activation volumes equal to -3.3 ± 0.3 cm3/mole for Si and -6.3 ± 0.60 cm3/mole for Ge. The results of this and other experiments are inconsistent with all bulk point-defect mechanisms, but are consistent with all interface point-defect mechanisms, proposed to date for thermal SPEG. A kinetic analysis of the Spaepen-Turnbull dangling bond mechanism shows it to be a highly plausible model for the growth process.
Monte Carlo Modeling of Interphase Boundaries in Cu-Ag and Cu-Ag-Au Alloys
Authors: Bacher P. , Wynblatt P. 
Published: March 2011

AbstractMonte Carlo simulation, in conjunction with the embedded atom method, has been used to model the composition and structure of a semicoherent (001) interphase boundary separating coexisting Cu-rich and Ag-rich phases in a binary Cu-Ag alloy. The results are compared with earlier simulations of the same boundary in a Cu-Ag-Au alloy, in which Au was found to segregate to the interface, and the boundary was found to be unstable with respect to break-up into {111} facets. The boundary in the binary system is also unstable to faceting, but displays both {100} as well as {111} facets. It is concluded that Au segregation in the ternary alloy plays an important role in stabilizing the {111} facets. The interplay between the misfit dislocations present at the interface, and the compositional features of the boundary are also discussed.
The Pseudostable Phase
Authors: Kikuchi Ryoichi , Mohri Tetsuo , Fultz Brent 
Published: March 2011

AbstractThe basic nature of kinetic processes is examined theoretically. When an isothermal development of order is studied theoretically, sometimes an ordered phase different from the final equilibrium one transiently predominates, while the free energy (Fsys) decreases monotonically although very slowly. There is another category of kinetic changes for which the convenient interpretation is that the Fsys surface itself changes in time. In this second category, a state can initially be a local minimum of Fsys and thus can be called a ‘metastable’ state, but after a certain time, as the Fsys surface itself changes, a kinetic path appears along which Fsys decreases and the system can change along it. To include both categories, the concept of the PSEUDOSTABLE phase is proposed. It is shown that even in the nucleation process, Fsys for the entire system decreases monotonically, although the local free energy may fluctuate.
Ionization Enhanced Solid Phase Epitaxy of Amorphous Silicon with Aluminum Impurities
Authors: Jeon Young-Jin , Becker M. F. , Walser R. M. 
Published: March 2011

AbstractIn this work we measured the functional dependence of the solid phase epitaxial regrowth (SPER) of amorphous silicon on NAI, the concentration of implanted aluminum (p-type). The SPER rates of self-ion amorphized layers in silicon wafers with (100) substrate orientation were measured by in situ high precision, isothermal, cw laser interferometry for temperatures from 470 °C to 550 °C, and concentrations in the range 3×1018 cm−3 ≤NAI≤ 4.7×1020 cm−3 obtained from samples implanted with three different doses.In the concentration range 3×1018 cm−3 ≤NAI≤ 2.3×1019 cm−3, we observed a “compensation effect” in which, with increasing NAI, the SPER rate decreased below the regrowth rate in intrinsic silicon and the activation energy of SPER increased to 2.85 eV, compared to 2.72 eV for intrinsic silicon. In the range 3.3×1019 cm−3 ≤NAI≤ 5.6×1019 cm−3, the regrowth rate increased linearly with NAI as previously observed for SPER in boron, phosphorus, and arsenic implanted samples. However, due to the compensation effect, the aluminum data could not be fit to the normalized equation; V/Vi = 1 + N/Ni, as was done previously for data obtained for boron, phosphorus, and arsenic. The regrowth rate increased nonlinearly to the maximum implanted concentration of 4.7× 1020 cm−3 at which the regrowth rate was more than double the previously observed maximum rate in boron doped silicon. In the high concentration range, the SPER rate enhancement could be fit by a quadratic equation whose curvature was positive as was the case for boron. This contrasts with the negative curvature required to fit the nonlinear dependence of the SPER rate on the concentration of donor impurities such as phosphorus and arsenic.
Thermionic Emission from Hot Tungsten Clusters
Authors: Leisner T. , Athanassenas K. , Kandler O. , Kreisle D. , Recknagel E. , Echt Olof 
Published: March 2011

ABSTRACTWe observe thermionic emission from tungsten clusters Wn, n ≥ 5, following excitation by a Q-switched Nd:YAG laser. The ion yield from this process dominates over prompt ionization if the laser fluence is chosen properly. Clusters originating from thermionic emission are significantly colder than expected if evaporative cooling would prevail.
Clusters-a New Source for Atomically Engineered Materials
Authors: Jena P. , Khanna S. N. , Rao B. K. , Manninen M. 
Published: March 2011

ABSTRACTThe electronic structure and properties of small clusters are strongly dependent on their size. These size specific properties are illustrated by confining the discussion to three different topics (1) interaction of hydrogen with clusters (2) effect of temperature and magnetic field on the magnetization of clusters and (3) reaction of clusters with gas atoms. It is shown that the electronic energy levels that are strongly dependent on cluster size give rise to the size specific electronic properties of clusters. In cluster hydrides certain elements are found to absorb more hydrogen per atom in cluster form than in a crystalline form. The magnetization of clusters increases as a function of cluster size and externally applied magnetic field. In clusters reacting with gas atoms, it is possible to find the product cluster in an electronically excited state. The energetics of these states are strongly dependent on the cluster size and the reacting gas.
Production and Characterization of Deposited Mono-Sized Clusters
Authors: Cox Donald M. , Kessler Barbara , Fayet Pierre , Eberhardt Wolfgang , Sherwood Rex D. , Kaldor Andrew 
Published: March 2011

ABSTRACTUsing high energy rare gas ion sputtering of metal targets, we are able to produce nanoamps of mass selected transition metal clusters. Mono-sized cluster ions are deposited at low kinetic energy upon substrates, e.g. silica or carbon, and are then characterized using UV and x-ray photoemission. In this paper we will discuss photoemission measurements of the 4f7/2core level energies of Au (1–5,7 atom samples) clusters deposited on silica. From such studies we are beginning to understand how electronic structure, cluster stability and mobility depend on (deposited) cluster size, surface coverage, and substrate temperature.