bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Roughness of Optical Oxide Coatings Deposited From Solutions and the Morphological Effect of Different Deposition Methods
Authors: Yoldas Bulent E. , Partlow Debbie P. 
Published: March 2011

ABSTRACTOptical coatings may be deposited from clear polymeric solutions derived from metal-organic compounds. These coatings are converted to their oxide counterparts upon heating at temperatures of 400–500°C. In this work, the surface roughness of solution deposited SiO2 films were investigated in order to assess their suitability for such applications as waveguides, mirrors, etc.SiO2 films deposited from polymeric siloxane solutions show rms surface roughness as low as 2.2Å in profile scans extending over 600 μm. The surface roughness of these films, as well as other properties, are found to be modified by the deposition method, e.g., spin or dip coating, as well as by the reaction parameters involved in the solution preparation.
Identification of Constituent Phases Within Thin Metal-Silicide Structures Using Surface X-Ray Diffraction
Authors: Jordan Harold , Seeharsha K. S. , Chunu D. W. 
Published: March 2011

ABSTRACTA relatively simple technique of surface x-ray diffraction (S-XRD) has been developed for the detection and identification of thin crystalline materials. The technique provides an abundance of diffraction lines with enhanced ability to detect and identify thin phases and to follow the sequence of phase formation within multiple-phase metal silicide structures.
Optical Properties of Hydrogenated Amorphous Carbon Films Grown From Methane Plasma
Authors: Pouch J. J. , Alterovitz S. A. , Warner J. D. , Liu D. C. , Lanford W. A. 
Published: March 2011

ABSTRACTWe have used a 30 kHz ac glow discharge formed from methane gas to grow carbon films on InP substrates. Both the growth rate, and the relative Ar ion sputtering rate at 3 keV varied monotonically with deposition power. The Ar ion etchigg rate of the films decreased with deposition power. Results from the 15N nuclear reaction profile experiments indicated a slight drop in the hyorogen concentration as more energy was dissipated in the ac discharge. Values for the inoex of refraction and extinction coefficient ranged from 1.721 to 1.910 and 0 to -0.188, respectively. Optical bandgaps as high as 2.34 eV were determined.
Current Status of thin film HgCdTe: Relationship of Structure and Chemistry to Device Application
Authors: Krikorian E. 
Published: March 2011

ABSTRACTThis paper addresses the current status of thin film HgCdTe and limitations in the currently achievable thin film properties. The emphasis is placed on Hg1−xCdxTe since this material is presently most seriously considered for infrared devices and particularly resistant to high quality film preparation due to large elemental vapor pressure differences. The current status of thin film HgCdTe is reviewed and the various thin film deposition techniques utilized to prepare HgCdTe thin films are compared. Finally, results are reviewed which still support the claim.that the less investigated technique of bias-sputtering, modified to accommodate deposition in a high partial pressure background of Hg vapor, can yield structurally high quality Hg1−xCdxTe films with device-worthy properties. Significant is the fact that the deposition process still provides the simple and systematic control over all relevant film properties without post-deposition treatment. Such control is required to achieve the desired material for device application. As is also reviewed here, this work was one of the first to demonstrate the ability to use low cost foreign substrates for HgCdTe thin film device fabrication.
Growth Behavior of Au on Semiconductor and Insulating Substrates
Authors: Alessandrini E. I. , Aboelfotoh M. O. , Laibowltz R. B. , Lacey J. A. 
Published: March 2011

ABSTRACTThere is a great deal of interest in forming Au grains on semiconductor and insulating substratcs for device application. Reduction in density of grain boundaries is known to cause improvement of clectromigration in thin films. Transmission electron microscopy and diffraction have been used to study the growth behavior and morphology of vapor deposited Au on these substrates. Electron beam evaporation techniques were used to evaporate Au at high rates (50Å/sec or higher) on substrates held at low temperature (Rm. Temp. to 250°C). Large Au grains laave been found to form on both amorphous (Si3N4 and SiO2) and single crystal Si substrates. The grain size of Au was also found to be dependent on substrate surface roughness; rough surfaces tended to retard the formation of large grains. Grains as large as 1/2 μ in a matrix of smaller ones were observed in films as thin as 350Å Annealing up to 350°C, subsequent to deposition, did not appreciably increase the size of the larger grains, although the smaller ones grew by about 10%. The TEM analysis together with RBS and AES data showed no significant interaction between Au and Si (that is to say no atomic intermixing or silicide formation) under all deposition conditions as well as annealing heat treatments. The significance of this in relation to the growth behavior of Au on the insulating and single crystal Si substrates will be shown.
The Influence of Sprayed (Cd, Zn)S on Dipped CuxS Composition
Authors: Berote G. , De Puydt Y. , Minet J -P. , Pierson E. , Streydio J -M. 
Published: March 2011

ABSTRACTIt is shown that the properties of sprayed (Cd, Zn)S layers obtained by means of a pneumatic nozzle depend dramatically on the type of flow gas used (air or nitrogen). The role of chemisorbed oxygen is demonstrated. Independently of the various heat treatments applied the resulting CuxS obtained has always a coefficient x closer to 2 when the flow gas is nitrogen. A subsequent annealing of the (Cd, Zn)S layers is found to increase the CuxS growth speed.It is also shown that the quality of (Cd, Zn)S layers determines to a great extent that of the cuprous sulfide in (Cd, Zn)S-CuxS heterojunctions. The data are interpreted in terms of the modification of the layers structure, composition and charge carrier concentration.
Secondary Grain Growth and Graphoepitaxy in thin Au films on Submicrometer-Period Gratings
Authors: Wong Chee C. , Smith Henry I. , Thompson C. V. 
Published: March 2011

ABSTRACTSecondary grain growth in thin Au films on SiO2 substrates with periodic surface relief structures was studied as a model for the application of graphoepitaxy (the growth of orientated crystalline films through the use of artificial surface patterning). Secondary grain growth driven by sur-face energy anisotropy produces grains many times larger than the film thickness with uniform texture. In thin films of Au on SiO2, surface-energy- driven secondary grain growth was found to occur at room temperature as soon as the film becomes continuous, and was shown to be responsible for the {111} deposition texture. A square-wave-profile grating of 0.2 μm period, etched into the surface of the substrate, resulted in preferred growth of {111}-textured grains with <112> directions oriented parallel to the grating axis. It is proposed that surface energy minimization is responsible for this phenomenon.
The Significance of the Impact Velocity of Vacuum-Deposited Atoms for the Structure of thin Films
Authors: Fuchs H. , Gleiter H. 
Published: March 2011

ABSTRACTThe goal in this study was to investigate the effect of the impact velocity of the atoms on the structure of thin films generated by vacuum deposition. For that purpose all atoms faster or slower than a pre-selected velocity, u, were removed with a velocity filter frm a beam of gold atoms obtained by thermal evaporation in vacuum (10−5 Pa). The residual atoms (with a velocity u)were deposited onto cold (80 K) glass substrates. The annealing behaviour of the films studied by means of d.c. resistance measurements indicates a correlation between film structure and impact velocity in the sense that films generated by means of low velocity atoms have a non-equilibrium structure which does not exist in films prepared by conventional vacuum deposition.
Epitaxial Relations in Fluoride Films Grown on GaAs{lll} and Ge(lll) Substrates
Authors: Tsutsui K. , Ishiwarya H. , Asano T. , Fijrukawa S. 
Published: March 2011

ABSTRACTEpitaxial relations in Cax Sr1−xF2(0⫶×⫶l) and BaF2 films grown on GaAs(111), (111) and Ge(111) substrates were investigated by He ion channeling analysis and transmission electron microscopy. Though the lattice constants of GaAs and Ge are nearly the same, the relations were found to be completely different. That is, the fluoride films on GaAs prefered to have an orientation identical to that of the substrate (type A orientation), whereas the orientation of the films on Ge was mainly rotated by 180° about the surface normal 〈111〉 axis (type B orientation). A hypothesis is proposed that the epitaxial relations in these systems are affected by the ionicity of the substrate as well as the lattice matching condition.
Defect States in Silicon Nitride
Authors: Robertson John , Powell Martin J. 
Published: March 2011

AbstractThe energy levels of defect centers in amorphous silicon nitride have been calculated. The results are related to recent photoemission and light-induced electron spin resonancedata. The Si dangling bond is argued to be the memory trap in MNOS devices and to be responsible for the electron accumulation at interfaces with amorphous silicon and for the n-type chargetransfer doping of amorphous silicon-silicon nitride superlattices.
On the Electronic Properties of Silicon-Tellurium Films
Authors: Faris F.A. , Al-Jassar A. , Wakim F.G. , Botros K.Z. 
Published: March 2011

AbstractSilicon and Silicon-Tellurium films were prepared in an ultrahigh vacuum system. The d.c. electrical conductivity of these films were measured under vacuum before exposing them to the air. The thermal activation energies of Silicon-Tellurium films were always found to be greater than that of Silicon films. Furthermore the optical measurements on Silicon-Tellurium films indicated that the optical gap of these films decreases as the concentration of tellurium in the films increases. Electron microscope examinations revealed that the films were amorphous in structure and homogeneous in composition.
A Carrier Lifetime Model for the Optical Degradation of Amorphous Silicon Solar Cells
Authors: Smith Z E. , Wagner S. 
Published: March 2011

AbstractThe light-induced performance degradation of amorphous silicon solar cells is described well by a model in which the carrier lifetimes are determined by the dangling bond density. The kinetics of the defect generation follow the model in which band-to-band recombination provides the energy for the creation of dangling bonds, which in turn introduce gap states that reduce carrier lifetime. Degradation will be slower in solar cells operating at lower excess carrier concentrations. This is documented with a comparison of degradation data for cells of different i-layer thickness, cells operating at open circuit vs. load, and for single vs. cascade cells. The model also correctly predicts the relation between short circuit current and fill factor degradation. At sufficiently long times, the efficiency will decrease at approximately the same rate for all cell structures and dimensions, with an offset in time between different device types which can be calculated.
Conduction and Threshold Switching in Amorphous Silicon
Authors: Sa-Neto A. 
Published: March 2011

AbstractWe report on measurements of conduction, threshold switching and high frecuency oscillations (∼100 MHZ) on amorphous silicon prgduced by RF sputtering in lateral devices with a very small (4µm2 to 40µm2 ) metalic contact area. The results show that the mechanism of threshold switching in this material is not due to the formation of a metalic filament through diffusion of the contacts. A small amount of Hydrogen (PH2/PAr=0.025) is sufficient to inhibit threshold switching. The “Zero voltage” resistance is reproducible and seems to be independent of the switching events.
Fabrication of Amorphous Silicon Devices on Plastic Substrates
Authors: Jeffrey F. R. , Vernstrom G. D. , Aspen F. E. , Jacobson R. L. 
Published: March 2011

AbstractAs Amorphous silicon devices spread into more products, the advantages inherant in continuous processing utilizing a plastic roll substrate will assume greater importance. Advantages include cost, ease of handling, shipping weight, steady state processing conditions and feedback control available in continuous processing. A new set of problems and constraints also comes with plastic substrates. These problems include mechanical strength with flexing, substrate surface defects, differential expalsion coefficients, shrinkage, and contaminant control. These problems along with efforts to evaluate and overcome them are discussed.
Defects in Tetrahedrally Coordinated Amorphous Semiconductors
Authors: Taylor P.C. 
Published: March 2011

AbstractIn the tetrahedrally coordinated amorphous semiconductors the dominant defects deep in the gap are attributed to dangling bonds on the group IV atoms. These defects are commonly thought to have effective electronelectron correlation energies Ueff which are positive, although some tightbinding estimates suggest negative Ueff. Defect states near the band gap edges are invoked to account for many experimental results including the usual appearance of an Urbach absorption edge. These shallow defect states are usually attributed to strained bonds but two-fold-coordinated group IV atoms have also been suggested. The application of light of near-band-gap energies alters the deniity of paramagnetic dangling bonds. For large spin densities (ns ≥ 1017 cm−3) this increase is probably due to the creation of new defects, bui it is possible that at lower densities (ns ≤ cm−3) the rearrangement of electronic charge in existing defects is important. Impurities also contribute to the defects observed in tetrahedral amorphous semiconductors. Particular species include trapped atomic and molecular hydrogen, trapped N0−2 molecules, singly-coordinated oxygen atoms and E' centers.
Grain Boundary Structures and Properties in Polycrystalline Silicon
Authors: Tsuo Y.S. , Milstein J.B. , Surek T. 
Published: March 2011

ABSTRACTThe method of preparation of polycrystalline silicon can have a strong influence on the types and distributions of grain boundaries, and thereby influence the electrical properties of devices made from such materials. Examples of methods employed in the preparation of polycrystalline silicon for solar cell applications include directional solidification (Czochralski pulling and various casting techniques), ribbon growth techniques (ribbon-to-ribbon, edgedefined film-fed growth, low-angle silicon sheet growth, edge supported pulling, silicon-on-ceramic), chemical and physical vapor deposition (CVD and PVD) on silicon and foreign substrates, recrystallization techniques (laser, electron beam), and others such as graphoepitaxy and electrodeposition. This paper reviews the important morphological features such as grain size and defect structures of the various polycrystalline silicon materials and the influence of growth parameters on these features. The effects of grain boundaries on the electrical and photovoltaic properties of various polycrystalline silicon materials will also be discussed.
Passive and Enhanced Grain Boundaries in Solar Cells by Gas Immersion Laser Diffusion
Authors: Turner G. B. , Tarrant D. , Aldrich D. , Pressley R. , Press R. 
Published: March 2011

ABSTRACTA new method for making p-n junctions based on immersion in a transparent dopant gas followed by irradiation with a pulsed laser is presented. The surface of the wafer melts, dopant from the gas dissolves in it, and is distributed by liquid diffusion before epitaxial regrowth. This technique, termed GILD for Gas Immersion Laser Diffusion, was used to make solar cells in both monocrystalline and polycrystalline silicon.Laser photocurrent scanning shows that grain boundary recombination is reduced or eliminated in cells made by the GILD technique and current collection is enhanced at some grain boundaries. Heat treatment at 850 ° C prior to GILD causes the same grain boundaries to be recombination active as they are in ordinary diffused cells.
Surface Mobilities in Laser-Processed Polysilicon Films
Authors: Frye R. C. , Ng K. K. 
Published: March 2011

ABSTRACTSurface mobilities in laser-processed polysilicon films were measured using silicon-gate n-channel thin-film transistors of varying dimensions. The apparent surface mobility inferred from transconductance measurements was found to be a decreasing function of channel length. For very short (~0.3/µm) channels, this mobility approaches the surface mobility of identical devices fabricated on bulk silicon. Furthermore, the temperature dependence of the surface mobilities in polycrystalline and bulk films was found to be identical.A novel EBIC technique was employed to examine the surface potential of transistors in operation. These measurements indicate a high degree of spatial nonuniformity in the inversion layer of polycrystalline films arising from the grain boundary region. A simple model of the transistors is presented which explains the geometry dependent surface mobility and its temperature dependence.
Metastable Barrier Voltage in ZnO Varistors
Authors: Gupta Tapan K. , Carlson William G. , Hall Barbara O. 
Published: March 2011

ABSTRACTA reversible change in barrier voltage is observed in assintered ZnO varistors upon application and removal of the applied voltage. This is attributed to a metastable component in the grain boundary Schottky barriers. Varistors show improved stability when the metastable component is removed or fixed by heat treatment.
A Method For The Tem Characterisation Of Grain Boundary Films In Ceramics
Authors: Jepps N.W. , Page T. F. , Stobbs W. M. 
Published: March 2011

ABSTRACTThe behaviour of Fresnel fringes with focus has been investigated as a means of characterising grain boundaries in engineering ceramics. This technique, together with dark-field imaging, has been applied to the study of grain boundaries in two hot-pressed silicon carbides. It is demonstrated that these two techniques, applied together, provide the best means of obtaining a complete characterisation of grain boundary films, in terms of width, structure, and composition.
Transport Across Silicon Grain Boundaries
Authors: Werner J. , Jantsch W. , Froehner K.H. , Queisser H.J. 
Published: March 2011

ABSTRACTBy comparison of the capacitance and the conductivity of p–type Si bicrystals, we show quantitatively that current transport occurs through thermionic emission of holes across the potential barrier, which is caused by charged donors in the grain boundary. Starting from this finding, we propose a simple model which allows for the first time a spectroscopic determination of the grain boundary density of states from photocapacitance data. Results indicate the presence of band tails and additional mid-gap states.
The Origin of Saline Groundwaters in Granitic Rocks: Evidence From Hydrothermal Experiments
Authors: Savage David , Cave Mark R. , Milodowski Antoni E 
Published: March 2011

AbstractHydrothermal rock-water experiments at 80°, 150° and 250° C have been carried out to investigate the origin of saline groundwaters in the Carnmenellis Granite, Cornwall, UK which have previously been attributed to be derived via dissolution of biotite and plagioclase feldspar by dilute meteoric groundwaters. The nature of product fluid and solid phases in the experiments was dominated by the dissolution of plagioclase and potassium feldspars, coupled with the precipitation of laumontite, calcite and smectite. However, the release of chloride from the rock was minimal, suggesting minor dissolution of the major chloride bearing mineral, biotite. The relative inertness and stability of biotite during the experiments was borne out by direct physical observation of reacted biotites and by consideration of the fluid phase composition in terms of thermodynamic mineral stability diagrams. It is concluded that the experimental and natural systems are buffered under different chemical conditions, which may be due to acidity generated via oxidation of localised sulphide zones within the granite and absent in the experiments. Dissolution of biotite may be an important mechanism for enhancing the salinity of groundwaters in granitic rocks if groundwaters are buffered to be outside the stability of biotite and convective circulation is significant.
Evaluation of Single-Hole Hydraulic Tests in Fractured Crystalline Rock by Steady-State and Transient Methods: A Comparison
Authors: Andersson J-E. , Persson O. 
Published: March 2011

AbstractThe results from a large number of single-hole packer tests in crystalline rock from three test sites in Sweden have been analysed statistically. Average hydraulic conductivity values for 25 m long test intervals along boreholes with a maximal length of about 700 m are used in this study. A comparison between steady state and transient analysis of the same test data has been performed.The mean vaule of the hydraulic conductivity determined from steady state analysis was found to be about two to three times higher compared to transient analysis. However, in some cases the steady state analysis resulted in 10 to 20 times higher values compared to the transient analysis. Such divergence between the two analysis methods may be caused by deviations from the assumed flow pattern, borehole skin effects and influence of hydraulic boundaries.
United States Crystalline Repository Project - Key Research Areas
Authors: Patera Edward S. 
Published: March 2011

AbstractThe Crystalline Repository Project is responsible for siting the second high-level nuclear waste repository in crystalline rock for the United States Department of Energy. A methodology is being developed to define data and information needs and a way to evaluate that information. The areas of research the Crystalline Repository Project is involved in include fluid flow in a fractured network, coupled thermal, chemical and flow processes and cooperation in other nations and OECD research programs.
Static Leaching of Fully Radioactive Waste Glass at 90°C in the Presence of Bentonite, Granite, and Stainless Steel Corrosion Products
Authors: Hermansson Hans-Peter , Björner Inga-Kari , Christensen Hilbert , Ohe Toshiaki , Werme Lars 
Published: March 2011

AbstractThe results from the JSS phase II static glass leaching experiments are presented. The experiments have been performed in the presence of bentonite, granite and stainless steel corrosion products at 90°C for 28 days. The leaching behaviour of Cs has been analysed using gamma-spectrometry. The surface of the leached glass samples has been analysed by infrared reflection spectrometry.The presence of uncompacted bentonite seems to have a very small, increasing, effect on the leach rate of the glass compared to when no bentonite is present. In the presence of compacted bentonite, a lower leach rate has beep founy than in the prgsencelof uncompacted bentonite. (For Cs 0.3 g × m−2 × d−1 and 0.7 g × m−2 × d−1 respectively.) The addition of stainless steel corrosion products seems to have a slightly increasing effect on the leach rate in the presence of compacted bentonite. The beneficial effect of granite on the leach rate seems to be overshadowed by the presence of uncompacted bentonite.