bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Synthesis Via Laser-Liquid Reactions
Authors: Partridge Julian P. , Strutt Peter R. 
Published: March 2011

ABSTRACTThe phenomena occurring when laser radiation interacts with a material submerged in a liquid depend on the power, wavelength, pulse duration, and liquid dielectric properties. Present studies, involving two distinctly different physical situations, show how some interaction modes can be used for surface modification. In the first, a continuouswave CO2laser-beam progressively pyrolyzes a liquid precursor to form a surface coating. Hexamethylcyclotrisilazane, for example, dissociates to produce highly adherent Si3N4 layers containing 200nm spherical particles. In the second physical situation, intense excimer laser radiation produces dielectric breakdown of the liquid, thus creating a high-temperature plasma and a high-pressure shock wave. Under these conditions, precursor decomposition products alloy the substrate to a depth of lum. Experiments above and below the substrate melt threshold have been used to determine the effects of processing in different power density regimes. A variety of analytical techniques have been employed to determine the compositions of the as-synthesised layers and mechanisms related to the observed phenomena are discussed.
Focused Ion Beam Sims for Micromachining Applications
Authors: Harriott L. R. , Vasile M. J. 
Published: March 2011

ABSTRACTA secondary ion mass spectrometry (SIMS) system has been incorporated into the AT&T-BL second generation focused ion beam (FIB) micromachining system. The primary applications are end-point detection and topographical element mapping. End-point detection of Cr micromachining on photomasks was done with raster sizes ranging from 10 μm x 10 μm to 3 μm x 3 μm. SIMS end-points, total ions images, and transmitted light measurements show that the ion-milling can be controlled to stop prior to or after the Cr/glass interface. Mass selected secondary ion images have been obtained for high yield ions such as52Cr+ and27 A1+ on raster fields of 25 μm in time intervals ranging from 20 to 100 sec. Al+ SIMS images of 1 μm lines and spaces from a VLSI test pattern have been obtained.
Room Temperature Uv Laser Continuous Direct Writing of Al From Tma
Authors: Bouree J.E. , Flicstein J. 
Published: March 2011

ABSTRACTAluminum lines have been drawn at a writing speed of 3.8 μm/s on (100) p-type Si by UV laser-assisted chemical processing, from a flow of TMA diluted in H2. These results are the experimental proof of direct writing at room temperature due to a single-step deposition process induced by a single light source. The useful (30 μQ-cm) ohmic-type resistivity obtained depends strongly on the photolytic process parameters.
Photoluminescent Properties of ZnO Layers Prepared by Organometallic Chemical Vapor Deposition
Authors: Bethke S. , Pan H-C , Wessels B. W. 
Published: March 2011

ABSTRACTZnO layers have been heteroepitaxially deposited on sapphire using organometallic chemical vapor deposition at atmospheric pressure. The quality of the layers was assessed using photoluminescence spectroscopy at 16K. The layers exhibited strong ultraviolet near bandedge luminescence. The dependence of near bandedge and deep level photoluminescence emission on deposition conditions was examined.
DCD and Low T Pl Determination of Bandgap Dependence on Composition for Mocvd Grown InGaAs/InP
Authors: Bassignana I. C. , Miner C. J. , Puetz N. 
Published: March 2011

ABSTRACTThis work reports a detailed study of the bound exciton recombination energy measured by low temperature (7K) photoluminescence, as a function of the relative lattice mismatch between the InGaAs epitaxial layers and the substrate measured by double crystal x-ray diffraction. Nominally undoped lμm and 2μm epitaxial layers of InGaAs/InP were grown by metal organic chemical vapor deposition (MOCVD). All InGaAs epitaxial layers used in this study show a single narrow rocking curve peak (FWHM < 25 arc-sec) and only a single narrow PL peak (FWHM < 2.5 meV). Near lattice match the PL energy varies linearly with the mismatch but the absolute value of the PL energy at lattice match is a function of the type of substrate used.
Tem Studies of GaAs/AlGaAs Heterostructures Grown on Patterned Substrates
Authors: Hwang D. M. , Kapon E. , Tamargo M. C. , Harbison J. P. , Bhat R. , Nazar L. 
Published: March 2011

ABSTRACTEpitaxical growth rates depend strongly on the crystalline orientations of substrate surfaces. Multilayer growth on pre-patterned substrates with various crystal facets exposed results in a large variation of layer thicknesses in the lateral direction. This lateral definition can be used in device applications. Alternating layers of GaAs and AIGaAs were grown by molecular beam epitaxy on (100) GaAs substrates patterned with grooves and ridges along the [01T] and [011] directions by chemical etching. The results were analyzed with transmission electron microscopy using vertical cross-section techniques. Examples of using this method to fabricate ridges with tips of atomic sharpness and quantum-well lasers are presented.
X-Ray Diffraction Study of a Thin GaAs Film on Si(100)
Authors: Bommannavar Arun S. , Sparks C. J. , Habenschuss A. , Ice G. E. , Dhere A. , Morkoc H. , Zabel H. 
Published: March 2011

ABSTRACTA 900A single crystalline GaAs film deposited by molecular beam epitaxy (MBE) on a silicon crystal cut 4.1° from (001) surface was characterized with X-ray diffraction measurements of the mosaic spread, particle size and strain distribution, and lattice parameter. The GaAs film had a larger mosaic spread in the direction of the steps of the silicon surface and coherent particle sizes of about 900 Å compared to the estimated film thickness of approximately 1000 Å. Superlattice reflections gave an ordered domain size of about 330 Å. There is a residual strain gradient in the film which is nearly linear with the lattice constant differing by about 0.044 Å between the surface of the film and its interface with the silicon substrate. Lattice parameter measurements indicate a small expansion of 0.13% perpendicular to the plane of the film.
The Influence of Current Stressing on the Structure of Ag Contacts to GaAs
Authors: Liliental-Weber Z. , Miret-Goutier A. , Newman N. , Jou C. , Spicer W.E. , Washburn J. , Weber E.R. 
Published: March 2011

ABSTRACTThe stability of Ag Schottky contacts on GaAs after voltage and current stressing has been investigated. The barrier height and its stability against voltage and current stressing were found to depend on the diode fabrication method (metal deposition onto either air-exposed or ultrahigh vacuum cleaved (UHV) substrates). The barrier height of Ag diodes formed on air exposed surfaces is 0.96 eV, and a significant decrease of 70 meV was found upon exposure to voltage and current stressing. In contrast, the barrier height of Ag diode formed on UHV cleaved samples is 0.89 eV, and no significant change was found upon exposure to stressing. The structure of the contacts was studied by transmission electron microscopy. Ag deposited on UHV cleaved substrates shows an epitaxial relationship to GaAs and atomically flat interfaces. Exposure to air before the metal deposition led to nonuniform reactions and compound formation at the interface as compared to UHV samples. After current stressing, void formation and electromigration of Ag was observed in the air-exposed contacts. Ag contacts formed on UHV-cleaved GaAs (110) were stable during current stressing.
Islanding and Surface Diffusion in Semiconductor Heteroepitaxy: Ge on Si
Authors: Fisanick G. J. , Gossmann H.-J. , Kuo P. 
Published: March 2011

ABSTRACTIslanding and surface diffusion for Ge on Si(111)7×7 and Si(100)2×1 surfaces were examined in a UHV apparatus with in situ scanning Auger/SEM capabilities. At room-temperature uniform growth is observed, while elevated temperatures lead to Stranski-Krastanov growth with complex island size distributions. Extensive surface diffusion is observed on Si(100)2×l; however, surface diffusion is demonstrated to be extremely sensitive to contamination with carbon on the order of ≈0.05 ML, as well as to e-beam irradiation.
Epitaxial Growth and Band Structure Effects at the Si/Ge(111) Interface
Authors: Woicik J.C. , List R.S. , Pate B.B. , Pianetta P. 
Published: March 2011

ABSTRACTX-ray absorption fine structure, Auger electron spectroscopy and low energy electron diffraction have been used to study the evolution of the lattice constant and the degree of intermixing of thin (∼5 Å) silicon films grown on the germanium(111) surface by solid phase epitaxy. Our results indicate that as the system is annealed, the silicon intermixes with the germanium at elevated temperatures to form a pseudomorphic Si-Ge alloy with the germanium bulk lattice constant. We further observe a splitting of the ‘white line’ Is absorption edge in crystalling Si, SiGe and dilute (<10% silicon) SiGe. The measured splittings agree with band structure calculations for Si, SiGe, and Ge, respectively, indicating that the density of conduction band states of SiGe behaves as the interpolation between the states of Si and Ge. Qualitatively, our spectra may be interpreted in terms of a one electron picture without invoking many body excitonic effects. The absorption edge of amorphous silicon is also presented and the features of the density of states due to long versus short range order are extracted.
The Atomistic Nature of Compound Semiconductor Interfaces and the Role of Growth Interruption
Authors: Madhukar Anupan 
Published: March 2011

ABSTRACTAn overview of the current understanding of the structural and chemical nature of interfaces involving an alloy layer, as revealed in photoluminescence and excitation spectra, is presented. Systematic studies, including reflection-highenergy- electron-diffraction measurements and computer simulations, reveal in-plane fluctuations in the alloy composition arising from the growth kinetics to be the dominant feature controlling the nature of the confining potentials in high quality samples grown without growth interruption. The role of surface kinetics in relaxing dynamic growth fronts to structurally smoother surfaces upon growth interruption is summarized and its pragmatic consequences for improving interface quality discussed.
Atomic Configuration of Coherent and Semicoherent Si/Ge Interface
Authors: Nandedkar A.S. , Narayan J. 
Published: March 2011

ABSTRACTAtomic positions near interfaces and defects are required to assess their physical properties. Their electronic properties can be calculated only after fixing the positions of atoms. The determination of atomic positions consists of three parts: (1) Theoretical calculations of atomic positions with appropriate interatomic potentials, (2) simulation of positions of atoms in the electron microscope, and (3) comparison of experimental results with the calculations. We have performed these three operations to determine atomic structures of coherent and semicoherent interfaces in Si/Ge systems. A coherent Si/Ge interface is simulated using a computer program. An edge dislocation is introduced at this interface with the help of elasticity theory. Energy minimization calculations are then carried out using interatomic potentials for germanium and silicon. The positions of atoms at the interface are thus determined. Critical phenomena in coherent and semicoherent interfaces are examined in relation to the strain energy of the system. For semicoherent interface containing dislocations, we can determine the critical thickness at which dislocations are generated. Energy minimization computations are found to play a major role in establishing critical phenomena. A model is also developed for the distribution of boron atoms near this dislocation. Isotropic elasticity theory is used for boron-dislocation interaction with correction factors inside the core to avoid singularities. Occupation probabilities of the atomic sites in the computational cell are calculated using the Fermi-Dirac distribution function. Interaction between boron atoms is neglected in the present analysis. Two configurations: 1. Si/Ge interface with a impurity free dislocation, and 2. the dislocation with boron impurities are then used to simulate high resolution images using the SHRLI computer program.
Investigation of the Promotion Effect of Germane in Low Temperature Uhv-Cvd Silicon
Authors: Uram Kevin J. , Meyerson Bernard S. 
Published: March 2011

ABSTRACTHigh quality, low defect density, single crystalline silicon/germanium alloys have been grown on Si(100) substrate wafers in a low temperature UHV-CVD reactor. Using a silane/germane gaseous source, the growth rate of the epitaxial layer increases from 4 angstroms/minute with no germane present to 82 angstroms/minute with 12.7% germane present in the reaction gas mixture at 550C. The germanium/silicon ratio in the deposited alloy is a factor of two greater than the germane/silane ratio in the reaction gas mixture. The kinetics of this effect are studied and correlation to UHV hydrogen thermal desorption from single crystal silicon-germanium alloys are made.
Stress Distribution and Critical Thickness of Thin Epitaxial Films
Authors: Sharan S. , Narayan J. , Jagannadham K. 
Published: March 2011

ABSTRACTWe have calculated the stress distribution and critical thickness for the growth of strained epilayers having various values of misfit between the epilayer and the substrate. During formation of epitaxial films, the growth (pseudomorphic) occurs upto a certain thickness with planar spacing normal to the interface being essentially the same both in the substrate and the film. Above a critical thickness it becomes energetically favorable for the film to contain dislocations. This occurs usually by generating glide dislocations near the free surface because there is a lack of dislocation sources in mostly “defect-free” semiconductor materials. We present an analysis of the critical phenomena in semiconductors based upon this experimental fact. In all the previous analyses, the critical step associated with the generation of dislocations was neglected. We also consider finite (island) growth of thin films and its effect on critical phenomena. The experimental results show the presence of glide dislocations in Ge/Si with the extra half planes in silicon substrate.
Clustering in the Epitaxial Growth of GaAs ON Si
Authors: Zinke-Allmang Martin , Feldman L.C. , Nakahara S. , Patel J.R. 
Published: March 2011

ABSTRACTWe report ion scattering and TEM investigations of the first layers of GaAs grown on clean Si(111). Based on observations of pure Ga cluster growth on As terminated Si(111) we propose a model for GaAs growth on Si, where Ga atoms are mobile and tend to cluster, but are immobilized by arriving As. These results establish conditions necessary for uniform film growth of GaAs/Si at the important film/substrate interface.
Chemical Beam Epitaxial Growth and Capacitance-Voltage Characterization of Si δ-Doped GaAs
Authors: Chiu T. H. , Schubert E. F. , Cunningham J. E. , Tsang W. T. , Tell B. 
Published: March 2011

ABSTRACTHigh quality GaAs layers have been grown by chemical beam epitaxy using triethylgallium and arsine. Undoped GaAs epilayer with net acceptor concentration NA - ND = 3}10 14cm-3 has been obtained at a low growth temperature of 500°C. Si dopant diffusion at such low temperature during growth is negligible. Using monolayer doping technique epilayers with Si impurities localized in a 2-dimensional plane were prepared. Capacitance-voltage profiling showed a high sheet electron concentration of lx1013cm-2 and peak widths of 22Å and 18Å at 300K and 77K, respectively, which are the narrowest ever reported. For samples grown or annealed at higher temperatures, significant impurity diffusion was observed.
Enhancements in Two Dimensional Electron Gas Density and Mobility in δ-Doped AiGaAs Heterostructures
Authors: Cunningham J. E. , Timp G. L , Schubert E. F. , Tsang W. T. , DeVegvar P. G. N. , Chiu T. H. , Agyekum E. 
Published: March 2011

ABSTRACTWe report our recent investigations of a new structure formed by b-doping the barrier of an AlGaAs/GaAs heterostructure. In this new structure we have observed both a mobility of 1.9×lO6cm2/Vsec and the fractional quantum hall effect. We compare low temperature mobilities and densities achieved with the δ-doped heterostructure with corresponding high values reported in the literature for the homogeneously- doped heterostructure. We show that systematic enhancements in both density and mobility occur in the b-doped heterostructure. By δ-doping both barriers of a quantum well we have also achieved electron concentrations of 4×1012cm -2 in the well.
Comparative Study of Interface Structure in GaAs/AlAs Superlattices By Tem and Raman Scattering
Authors: Nakamura T. , Ikeda M. , Muto S. , Komiya S. , Umebu I. 
Published: March 2011

ABSTRACTTransition layers in GaAs/AlAs superlattices were studied by high resolution transmission electron microscopy (HRTEM) observations and Raman scattering measurements. We clarified that arrays of bright spots at the interface in the TEM image is a good indicator of the interfacial configuration and that a high atomic step density with intervals of less than 10 nm is necessary for Raman characterization using confined LO phonons.We characterized the growth temperature dependence of the transition layers at the GaAs/AlAs interfaces. For a sample grown at 500'C, the extent of the transition layers is about one monolayer and that of the interfacial step intervals is more than 10 nm. For a sample grown at 700 0 C, these values are about two monolayers and less than 3 nm, respectively.
The Organometallic Epitaxy of Hgcdte for Infrared Detector Applications
Authors: Ghandhi S.K. 
Published: March 2011

ABSTRACTThis paper reviews the requirements for mercury cadmium telluride material which is suitable for far infrared detectors. This is followed by substrate and reactor considerations, leading to its direct alloy growth by organometallic vapor phase epitaxy.It is shown that HgCdTe can now be grown with electrical properties and areal compositional uniformity that are suitable for focal plane arrays, operating in the 10.6 Am range.
A Comparison of (100) Hg1−x Cdx Te and Hg1−x ZnxTe Grown By Molecular Beam Epitaxy
Authors: Feldman R. D. , Austin R. F. , Bridenbaugh P. M. 
Published: March 2011

ABSTRACTFilms of HgCdTe with x < 0.6 and of HgZnTe with x < 0.26 have been grown by molecular beam epitaxy (MBE). Very high electron mobilities have been achieved for both materials in the small bandgap region. Hall mobilities at 77K reach 4.8 × 105 cm2 /V-s for Hg0 87 Zn0.13 Te, and 3.1 × 105 cm2/V-s for Hg0.87 Zn0.13 Te. HgCdTe growth was easily extended to the 1.5 – 3 μm wave length range. Attempts to extend HgZnTe to these bandgaps were unsuccessful due to defects that are induced by surface roughness in high Zn-content films. These results suggest that HgCdTe is the more suitable material for MBE growth for near infrared applications.
Role of Film-Substrate Interaction in Determining the Morphology of Thin Films
Authors: Grabow Marcia H. , Gilmer George H. 
Published: March 2011

ABSTRACTThe equilibrium structure and metastable states of thin films have been investigated using molecular dynamics computer simulations. The energy as a function of coverage for a variety of film/substrate systems has been determined, and this information has been used to determine the growth mode and the conditions under which the film is dislocation free. In particular, the influence of the strength of the film-substrate binding will be discussed.
The Effect of Layer Thickness on the Reaction Kinetics of Nickel/Silicon Multilayer Films
Authors: Clevenger L. A. , Thompson C. V. , Cammarata R. C. , Tu K. N. 
Published: March 2011

ABSTRACTDifferential Scanning Calorimetry (DSC) and Debye-Scherrer X-ray diffraction have been used to characterize silicide formation in nickel/amorphous-silicon multilayer films. Two different Ni:Si layer thickness ratios were investigated, 3:11 and 1:1. Films with layer thickness ratio of 3:11 first formed Ni2Si followed by NiSi at a temperature 25°C higher. Multilayer films with 1:1 thickness ratios formed only Ni2Si. Activation energies for these reaction were determined and found to be in agreement with previous results on bilayer films. The temperature at which Ni 2Si formation was complete in the 1:1 films was found to decrease with decreasing layer thickness. Analysis of this phenomenon allowed determination of the interdiffusivity during silicide formation, also in agreement with previous results. Films with 1:1 layer thickness ratios and layer thickness of 125 Å or less were found to sometimes undergo explosive silicidation. This presumably occurs because the rate of heat generation at the reacting interfaces exceeds the rate of heat dissipation.
Fabrication and Evaluation of Transmissive Multilayer Optics for 8keVX Rays
Authors: Bionta R. M. , Jankowski A. F. , Makowiecki D. M. 
Published: March 2011

ABSTRACTWe have made and tested several sliced multilayer structures which can function as transmissive x-ray optical elements (diffraction gratings, zone plates, and phase gratings) at 8 keV. Our automated multilayer sputtering system is optimized to sputter layers of arbitrary thickness for very large total deposits at high deposition rates. Diffraction patterns produced by the multilayer devices closely match theoretical predictions. Such transmissive optics have the potential for wide application in high resolution microscope and spectrometer systems.
Mon-Tin Superconducting Artificial Superstructure Film
Authors: Kawaguchi Kenji , Shin Shigemitsu 
Published: March 2011

ABSTRACTWe succeeded in synthesizing MoN-TiN superconducting artificial superstructure film (SASF). The structure of MoN layers is estimated to be γ-Mo2 N. The behavior of Tc in SASFs is recognized by a proximity effect using adjustable parameters of bulk Tc. Calculated parameters are, however, different from Tc of single layered films.
Multilayered Interconnections for VLSI
Authors: Gardner Donald S. , Saraswat Krishna 
Published: March 2011

ABSTRACTInterconnections are predicted to become the limit in performance and reliability at submicron dimensions. Layered structures are one possible solution to the problems of electromigration and hillocks. Aluminum alloys can improve the properties of pure aluminum but with a consistent increase in resistivity due to lattice distortions introduced by the alloy in solid solution. The rise in resistivity is minimal in layered films because aluminum layers act as parallel conductors. Titanium is the most effective refractory metal for eliminating hillocks in layered films; however vanadium, tantalum, and tungsten also reduce hillocks to a manageable level although high resistivity, the inability to dry etch, or lateral hillocks can become a problem. Layered films of aluminum with TiSi2 encounter problems with hillocks. These differences are partially explained by the increased strength of the aluminide TiA13 that forms compared to the other compounds. Barrier metals are needed for aluminum layered with refractory metals because of the formation of ternary compounds, and several metals have proven to be satisfactory. Such barriers, however, are required for even aluminum at submicron dimensions for stable low-resistivity contacts.
MBE Growth of Compositionally Modulated Ceramics
Authors: Mckee R. A. , List F. A. , Walker F. J. 
Published: March 2011

ABSTRACTAn ultra high vacuum system fitted with thermal effusion cells that heat 20cc of material to temperatures as high as 2000 °C is being used to synthesize thin film and multilayer ceramics from their constituent elements. A molecular source for oxygen used in conjunction with these effusion cells allows oxides of Al, Ti, Cu, and Y to be grown with compositional modulation controlling growth rate and stoichiometry.