bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial Inhomogeneities of the Luminescence and Electrical Properties of Mbe Grown GaAs on Si
Authors: Reid G.A. , Nauka K. , Rosner S.J. , Koch S.M. , Harris J.S. 
Published: March 2011

AbstractSpatial homogeneity of the luminescence and electrical properties of gallium arsenide films grown directly on silicon substrates (GaAs/Si) by molecular beam epitaxy (MBE) have been investigated with microscopic scanning photoluminescence (PL), cathodoluminescence (CL), electron beam induced current (EBIC), and scanning deep level transient spectroscopy (SDLTS). It was found that GaAs/Si exhibits a highly nonuniform lateral distribution of speckled appearance in CL and PL images. These centers are also responsible for short minority carrier lifetimes as determined by EBIC. The observed nonuniformities appear to be a fundamental material property which is not altered by post-growth annealing. Correlations between the luminescence and electrical inhomogeneities and structural defects will be discussed.
Strain in Graded Thickness GaAs/Si Heteroepitaxial Structures Grown with a Buffer Layer
Authors: Nemanich R.J. , Biegelsen D.K. , Street R.A. , Downs B. , Krusor B.S. , Yingling R. D. 
Published: March 2011

AbstractThe strain in MBE GaAs/Si heterostructures grown with a buffer layer are characterized by Raman scattering and luminescence. A graded thickness sample was produced by slowly moving a shutter in front of the sample during the growth. Raman scattering and luminescence measurements made as a function of distance could be related to the strain in the film as a function of film thickness. The measurements showed tensile strain for all thicknesses. The strain in the overlayer was accounted for by the difference in thermal expansion of GaAs and Si. The buffer layer showed the largest tensile strain, and it is proposed that this strain was due to the presence of vacancies.
Reduction of Strain in Epitaxial GaAs on CaF2/Si Substrates
Authors: Hashimoto Shin , Schowalter L.J. , Smith G.A. , Lee E.Y. , Gibson W.M. , Claxton P.A. 
Published: March 2011

AbstractThis paper reports on strains in epitaxial GaAs layers grown on CaF2/Si(001) and CaF2/Si(111) heteroepitaxial substrates investigated by MeV 4He+; ion channeling. The results indicate that the CaF2 buffer layers reduce strain in the GaAs.
Defects in Large-Misfit Heteroepitaxy
Authors: Eaglesham D.J. , Aindow M. , Pond R.C. 
Published: March 2011

AbstractA Transmission Electron Microscopy (TEM) study is presented of GaAs on Si (100) and CdTe on GaAs (100), and the implications for defect nucleation mechanisms are discussed. MOCVD GaAs/Si is shown to grow by island nucleation followed by 3D growth. Single islands are free of inversion domain boundaries (or “APBs”) implying that a single domain is able to grow over a demi-step on the substrate surface during this 3D growth. Misfit dislocations are shown to be edge type during island growth, with 60° type being generated at island junctions. The predominant threading dislocations are found to have inclined a/2 <110> Burgers vectors. The implied mechanisms for the generation of both misfit and threading dislocations are discussed. In MOCVD CdTe/GaAs the microstructure is shown to have a number of qualitatively similar features; in addition, study of this much larger misfit system allows us to deduce a possible explanation for misorientation effects in these systems.
Heteroepitaxy of GaAs, GaP and InP on Si By Omvpe and Their Application to thin Film Solar Cells
Authors: Yamamoto Akio , Yamaguchi Safumi 
Published: March 2011

AbstractOrganometallic vapor phase epitaxial (OMVPE) growth of GaAs, GaP and InP on Si has been studied using the two-step growth method. Growth parameters for a heteroepitaxial film with a specular surface, a single-domain structure and high crystallinity are demonstrated and discussed. Residual strains in grown films are evaluated and analyzed by taking account of elastic lattice deformation due to lattice mismatch or thermally- induced strain accomodation by rearrangement of misfit dislocations. Thin film GaAs and InP solar cells are fabricated and their performances are discussed in relation to defect density in the films. For GaAs cells, an efficiency of 18 % (AM1.5, active area) is attained by reducing defect density to 2×106 >cm−2 . The defect density is ~. 5×107 cm−2 in the present InP films, and is needed to be less than 106 cm−2 to attain an efficiency of 18 %.
Low Pressure Mocvd Growth and Characterization of GaAs and InP on Silicon Substrates
Authors: Razeghi M. , Defour M. , Omnes F. , Nagle J. , Maurel P. , Acher O. , Huber A. , Mijuin D. 
Published: March 2011

AbstractHigh quality GaAs and InP have been grown on silicon substrates, using low pressure metalorganic chemical vapor deposition technique. The growth temperature is 550ºC andthe growth rate 100 A/min.Photoluminescence, X-ray diffraction and electrochemical profiling verified the high quality of these layers. The use of superlattices as buffer layers, (GaAs/GaInP) in the case of GaAs/Si and (GalnAsP/InP) in the case of InP/Si, decreased the amount of misfit dislocations in the epitaxial layer. Carrier concentrations as low as 5.1015 cm-3 have been measured by electrochemical profiling.
Heteroepitaxy on Silicon by Molecular Beam Epitaxy
Authors: Schowalter Leo J. 
Published: March 2011

AbstractIn recent years extensive research has been conducted on growing heteroepitaxial layers of insulators, metals, and other semiconductors on silicon. This work promises to extend the use of Si (or, at least, Si substrates) far beyond present day devices into hybred semiconductor devices, optoelectronics, ballistic electron devices, and three-dimensional device structures. However, the “art” of heteroepitaxy is still poorly understood and much work remains to be done to realize most practical applications. Molecular beam epitaxy (MBE) represents an attractive technique for research and development of heteroepitaxy because of its relatively low growth temperatures, flexibility in working with different materials, and by providing a good environment for in-situ observation of the heteroepitaxial process. Using examples from recent heteroepitaxial work by molecular beam epitaxy in the areas of CaF2, NiSi2 and CoSi2, and GaAs on Si, this paper discusses how heteroepitaxial quality is affected by the relative surface free energies and strain (due to both lattice and thermal expansion coefficient mismatch). The goal is to produce better heteroepitaxial layers for device applications by an improved understanding of the process.
Epitaxial Growth of Inp on Si by Mocvd
Authors: Konushi F. , Seki A. , Kudo J. , Sato H. , Kakimoto S. , Fukushima T. , Kubota Y. , Koba M. 
Published: March 2011

AbstractThe heteroepitaxy of InP on Si substrates was investigated using MOCVD. A thin GaAs intermediate layer was used to alleviate the 8.4% lattice mismatch between InP and Si. With the use of this intermediate layer, four inch size, single domain InP epilayer with small residual stress was reproducibly grown on off-(100) oriented Si substrates. The etch pit density (EPD) of as-grown InP layer was 5x107~1x108 cm-2 . The post growth annealing of this epilayer at 800~850ºC in aPH3+H2 ambient reduced EPD to 1~2x107 cm-2
Heteroepitaxial Growth of Sic on Si - Highly Mismatched System -
Authors: Matsunami Hiroyuki 
Published: March 2011

AbstractSingle crystals of cubic(beta) SiC were heteroepitaxially grown on Si to ameliorate the large lattice mismatch of 20 %. The structure and the role of the carbonized layer used for crystal growth are discussed. Single crystals were successfully grown on Si(100) and(111). Antiphase domains on Si(100) were examined to obtain smooth surfaces. The use of Si(100) off-axis substrates oriented towards [011] allowed the successufulelimination of the antiphase domains. Anisotropy was found in the electrical properties of SiC on off-axis substrates. Possible applications are described.
Substrate Strain Measurements in Mbe Grown Silicon on Sapphire
Authors: Pellegrino Joseph , Qadri Syed , Richmond Eliezer , Twigg Mark , Vold Carl 
Published: March 2011

AbstractAn x-ray diffraction study is made of the effect of silicon film thickness on the peak broadening associated with the (024) sapphire Bragg reflection peak for MBE—grown SOS material. The predeposition treatment and growth parameters for the samples in the series were identical. The thicknesses ranged from 5500 to 40,000 angstroms and the growth rate was roughly I angstrom/second.SOS films with silicon thicknesses below 5500A did not produce sapphire peak broadening when compared with the corresponding sapphire standard. With reference to standard sapphire reflection peaks, the 5500A film shows slight broadening while a I micron film broadened 14 seconds of arc when compared at FWHM with the sapphire standard. A possible explanation for this is that at overlayers less than 5500A, the film is not sufficiently massive to exert a uniform strain on the sapphire. At 5500A the film attains a critical thickness sufficient to strain the substrate and produce detectable broadening. For thickerfilms the strain would increase proportionally. Results from lattice parameter measurements on the silicon epilayer indicate that the perpendicular lattice parameter relaxes atgreater thicknesses but is still in tension when compared with bulk silicon. One would expect that the strain gradient suggested by these results would be greatest at the silicon/sapphire interface and that the defect concentration at the interface might beaffected by this strained condition.
Laser Probing of the Dynamics of Ga Interactions on Si(lO0)
Authors: Carleton Karen L. , Bourguignon Bernard , Smilgys Russell V. , Oostra Doeke J. , Leone Stephen R. 
Published: March 2011

AbstractThe kinetics of desorption and scattering of Ga atoms on Si(100) surfaces are probed by laser-induced fluorescence detection of the gas phase species and by Auger analysis of the surface composition. The kinetic parameters are correlated with the structures deduced by LEED and the coverages determined by Auger spectroscopy. The binding energy of Ga on Si(100) is found to be a function of coverage, starting out at 2.9 eV at low coverages and decreasing to 2.3 eV for coverages between 0.5 and 1 monolayer (ML). Ordered growth is always observed for coverages below 1 ML, but above one monolayer the growth of islands occurs on the wellordered monolayer. The onset of island formation is a strong function of temperature. A model is proposed for the structures and energetics involved in the growth of Ga on Si(100). The results are discussed in terms of the implications for epitaxial growth of GaAs on Si.
Low Temperature in Situ Cleaning of Si(100) Surfaces and Transmission Electron Microscopy of Subsequent Growth of Epitaxial Germanium
Authors: Rudder R.A. , Hattangady S.V. , Posthill J.B. , Markunas R.J. 
Published: March 2011

AbstractA low temperature process for cleaning Si(100) surfaces has been developed. It involves a combination of a modified hot RCA wet chemistry treatment and an in situ hydrogen treatment for the removal of oxides and carbonaceous material from the Si surface. While this treatment is successful in producing reflection high energy electron diffraction patterns which show 1/2-order reconstruction lines, subsequent Ge heteroepitaxial growth at 300°C contains a high density of microtwins. Transmission electron microscopy reveals that most of the microtwins do not propagate to the wafer surface. Furthermore, the Ge/Si interface is not abrupt, and there are regions that do not appear crystalline. This suggests that some contamination is still present on the Si(100) surface after the in situ hydrogen treatments.
Photoemission Optogalvanic Spectroscopy: An in situ Plasma-Surface Diagnostic
Authors: Downey Stephen W. , Mitchell Annette , Gottscho Richard A. 
Published: March 2011

AbstractAn obstacle to better design and control of plasma processes is our limited ability to monitor surface properties in situ. We describe a new plasma diagnostic technique, photoemission optogalvanic spectroscopy, which can be used to monitor surface contamination, etching rates, and end points. The experiment consists of irradiating a surface with a pulsed excimer or dye laser whose photon energy is above the substrate work function. Photoemission of electrons from the surface is detected by monitoring changes in the discharge current (optogalvanic effect). The technique is characterized by measuring signal strengths as a function of laser intensity, laser wavelength, and bias voltage in vacuum and in an Ar plasma. The technique is used to monitor contamination and etching end points in F-containing plasmas.
Particle Size Measurement in Optical Waveguide Manufacturing Torches Using Dynamic Light Scattering
Authors: Bautista J. R. , Potkay Eugene , Scatton Daria L. 
Published: March 2011

AbstractThe characterization of silica “sooting” torches used in optical waveguide manufacture by external flame-hydrolysis deposition processes such as Outside Vapor Deposition (OVD) and Vapor-phase Axial Deposition (VAD) prflents a formid.ble high temperature environment at > 2000°C in the presence of > 1012 particles/cm3 of silica. This paper describes the first application of Dynamic Light Scattering (DLS) to probe particle sizes in an actual lightguide burner following the “triple-flame” VAD design. DLS, also termed Photon Correlation Spectroscopy (PCS) or Diffusion Broadening Spectroscopy (DBS), was previously identified as a viable diagnostic tool for in-situ particle measurements in silica-sooting flames by W. L. Flower [1] and through an earlier collaboration between AT&T and the Sandia Combustion Research Facility. In applying DLS, however, our experience with the VAD torch reveals that a specialized experimental method will undoubtedly be required to deal with the inevitable presence of low frequency system instabilities in industrial systems.
Spontaneous Raman Scattering for Gas Phase Diagnostics
Authors: Drake Michael C. 
Published: March 2011

AbstractThe use of spontaneous rotational and vibrational Raman scattering for nonperturbing measurements of temperature and gas phase concentrations in combustion and in materials processing is reviewed. Theory of Raman intensities is briefly discussed and examples of Raman scattering from metal halide vapors in high temperature furnaces, laminar flames, and turbulent flames are given to demonstrate its capabilities and limitations. At present spontaneous Raman scattering is the only method which can provide simultaneous nonperturbing measurements of temperature and many species concentrations with high spatial (≤ 0.1 mm3) and temporal (≤ 1μs) resolution. Rotational Raman scattering is generally preferred for low temperature measurements (≤ 1200 K), and vibrational Raman scattering is better for measurements of higher temperatures and of multiple-species concentrations. The disadvantages of Raman scattering stem for the weakness of the nonresonant Raman interaction which limits its sensitivity to major species concentrations, renders it vulnerable to interferences from other sources of visible radiation, and requires high powered lasers and sensitive detectors. Data from Raman scattering measurements, particularly when coupled with data from other laser diagnostic techniques and when compared to computer model calculations, have led to a better understanding of the complex interactions between fluid mechanics and chemical reactions which can govern the operation of turbulent combustors or chemical flow reactors.
Laser Probes and Numerical Modeling as Process Diagnostics in Chemical Vapor Deposition
Authors: Breiland William G. , Ho Pauline , Coltrin Michael E. , Kee Robert J. , Evans Greg H. 
Published: March 2011

AbstractThe chemical vapor deposition process consists of a chemicallyreacting flow in which the fluid mechanics and chemical kinetics are strongly coupled. Laser probes such as Raman spectroscopy and laserinduced fluorescence can be used to measure gas temperature fields and chemical species concentrations, but often the interpretation of such data is difficult because several interacting chemical and physical phenomena are occuring simultaneously. Detailed numerical modeling of the experinmental system under study provides valuable insights into these interactions and allows one to make useful comparisons between experiment and the model to gain a fundamental understanding of the CVD process. Examples of this approach are given for silicon deposition from silane and fluid mechanics diagnostics in a rotating disk CVD reactor.
Optical Diagnostics for Metallurgical Processes.
Authors: Williamson R. L. , Peebles H. C. , Hareland W. A. , Zanner F. J. 
Published: March 2011

AbstractMany industrially important metallurgical processes are accompanied by the emission of light, the analysis of which often supplies useful information concerning the current state of the process while also providing insight into the details of specific process mechanisms. Optical diagnostic techniques are finding an increasingly wide range of application throughout the metallurgical community. This paper discusses the application of emission spectroscopy and imaging techniques to the analysis of such diverse processes as vacuum arc remelting, laser welding, and arc welding. A discussion of these techniques will be presented addressing such subjects as instrumentation, data analysis, the kind of information available and its potential impact on the selection of process parameters. Special attention will be given to discussing the difficulties encountered in applying these diagnostic technologies to “real life” processes in non-laboratory environments.
Aluminium-Transition Metal Thin-Film Reactions
Authors: Colgan E. G. , Mayer J. W. 
Published: March 2011

AbstractA systematic study of Al/metal reactions has been performed. The thin-film interactions of Al with refractory metals (Ti, V, Ta, Cr, Mo, W and Co) and near-noble metals (Ni, Pd, and Pt) have been investigated. The initial aluminide phases to grow are the Al-rich phases: TiAl3, Val3, TaAl3, Cr2Al13, MoAl12, Wal12, Co2Al9, NiAl3, Pd2Al3, and Pt2Al3 at temperatures between 225 and 525°C. With the exceptions of Val3, Pd2Al3, and Pt2Al3. these are the most Al-rich phases on the phase diagrams. Marker experiments were performed and Al was the dominant diffusing species during the growth of these phases, TiAl3, Val3, Cr2Al3, MoAl12, Co2Al2, NiAl3, Pd2Al3, and Pt2AI3. Consistent with the faster Al diffusion, which provides a greater supply of Al to the growing interface, is the growth of the most Al-rich phase initially. For the exceptions to this rule, Val3, Pd2AI3, and Pt2 Al3, the complexity of the Al-rich V, Pd, and Pt end phases may have hindered nucleation, resulting in the growth of the observed phases. The subsequent phase formation was examined in the Ni-, Pd-, and Pt-Al systems. After initial phase formation consumed all the Al or metal, subsequent phases formed in accordance with the overall stoichiometry. The results of this study, along with a brief literature review, are presented and the generalized behavior of Al/transition metal reactions discussed.
Studies on the Adhesion of Au Films to GaAs
Authors: Bardin T. T. , Pronko J. G. , Senbetu L. , Kozak D. A. 
Published: March 2011

AbstractThe influence of a number of substrate conditions and interfacial contaminants on the adhesion strength of thin Au films (10 to 100 nm thick) to GaAs substrates was studied. The GaAs surfaces were prepared by cleaving on the <110> plane under controlled atmospheres and conditions prior to depositing the Au film. Adhesion strengths were measured using the pinpull test. The study included standard characterization techniques to examine the substrate surface and the Au-GaAs interfaces. A direct correlation was found between cases of poor adhesion and the presence of hydroxyl groups on the GaAs surface. The influence of post evaporative treatments to improve the adhesion of specific cases was also studied.
Growth Characteristics of Co-Cr Thin Films for Magnetic Recording
Authors: Demczyk B. G. , Laughlin D. E. 
Published: March 2011

AbstractThe growth characteristics of magnetron sputtered Co-22%Cr thin films on amorphous glass or carbon substrates have been investigated utilizing transmission electron microscopy,. X-ray diffraction, electrical resisivity and in-plane stress measurements. Results indicate that the initial deposit is “amorphous”, but that isolated islands of small crystallites form before the film reaches 5nm film thickness. By 10nm, well oriented grains with hcp c axis perpendicular to the film plane develop, and by 50nm, a twinned columnar microstructure is evident. As this occurs, the in-plane film stress becomes constant. Also, we have observed a distinct subgrain structure in the thinner films (10–50 nm), and this is reflected in the electrical resistivity. This cannot be accounted for by an “evolutionary selection” growth scenario, but must be related to the low surface mobility of adatoms at these low substrate deposition temperatures.
Interfacial Reactions Between Co and GaAs
Authors: Shiau F.-Y. , Zuo Y. , Zheng X.-Y. , Lin J.-C. , Chang Y. A. 
Published: March 2011

AbstractInterfacial reactions between Co and GaAs have been studied using bulk diffusion couples of Co (∼0.5 mm thick)/GaAs and thin-film Co(∼-40 nm) on (001)GaAs as well as the epitaxial formation of CoAs and CoGa on (001)GaAs. In addition, phase diagram of Co-Ga-As at 600°C was determined. The thin-film results are rationalized in terms of the phase diagram and bulk diffusion data.
Modification of Copper Surfaces: Effect on Adhesion at the Copper Polyimide Interface
Authors: Parekh P. P. , Kembaiyan K. T. , Gonsalves K. E. , Bocarsly A. , Amos L. 
Published: March 2011

AbstractCopper surfaces were derivatized resulting in the formation of Mx[Cu(II)(CN)Fe(II/III)(CN)5] at the interface. Polyimides were spin coated onto the modified metal surfaces and the degree of adhesion measured by the tape pull test. Effects of mechanical interlocking were evident in the case of modified copper samples, due to derivatization by ferricyanide. The chemical bonding and elemental analyses of the interfaces were studied by XPS and SEM.
Surface Characterization of Sputter Etched Polymer Films
Authors: Grant J. L. , Dunn D. S. , McClure D. J. 
Published: March 2011

AbstractThe surface chemical changes induced in polystyrene, polypropylene and poly(ethylene terephthalate) (PET) by argon and oxygen rf sputter etching were studied by XPS and infrared reflection absorption spectroscopy (IRRAS). Thin (∼5nm) chemically modified surface layers were observed for all three materials. Polystyrene surfaces were oxidized by sputter etching in both oxygen and argon with differing chemical functionality resulting from etching in the different gases. Polypropylene surfaces, by contrast, were oxidized with similar chemical functionality resulting from etching in either gas. PET surfaces were oxidized slightly by oxygen sputter etching and reduced by argon sputter etching. For the model systems chosen, etch mechanisms are suggested based on trends in the chemical modification behavior.