bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of Oriented Conductive SrVO3-x(SVO) Films on Si(100) Substrates by Evaporation in Low-Pressure Hydrogen
Authors: Hayashi Tsunemasa , Ishiwara Hiroshi 
Published: March 2011

AbstractConductive SrVO3-x films are deposited directly on Si(100) substrates by vacuum evaporation method using SrVO3-x as a source material. It has been found that the conductive film was strongly oriented to only <100> direction on Si(100). By introducing hydrogen, the resistivity of the SrVO3-x film decreases to 0.57mΩcm, which is smaller than those of samples deposited without hydrogen.
Strained Layer Growth: how do 3d Islands Relax Strains?
Authors: Priester C. , Lefebvre I. , Allan G. , Lannoo M. 
Published: March 2011

ABSTRACTWe study the elastic strain relaxation in highly strained layers deposited on a [001] substrate induced by coherent 3D islanding. We first calculate the elastic strain distribution within several pyramidal 3D islands with different faces (the observed ones being usually [114] or [014]). For this, we use a valence force field (VFF) description. Our calculation includes interactions between islands, which appear to be a key parameter. We study how the shape of the island modifies the strain relaxation which is proved to vary within the island. Very simple considerations on surface tension indicate why pyramidal islands are the most stable.
A new Physical Picture for Surface Diffusion at High Temperatures
Authors: Suni I. I. , Seebauer E. G. 
Published: March 2011

ABSTRACTSurface diffusion of In and Sb on Ge (111) has been measured by optical second harmonic Microscopy. This technique employs surface second harmonic generation to directly image submonolayer surface concentration profiles. At low coverage, the activation energy Ediff and pre-exponential factor D0 are extraordinarily large for both systems and cannot be explained by theories based on simple site-to-site hopping.Molecular dynamics simulations of a Lennard-Jones (111) surface has revealed a new mechanism for high-temperature diffusion which is probably operative on Ge (111). At low coverages and high temperatures, adatoms sink into the top layer of Ge, and diffusion is dominated by thermal formation of adatom-vacancy pairs. This process is characterized by a high enthalpy of pair formation and a high entropy of activation due to lattice relaxation near the vacancy.At high coverages, the behaviour of Sb and In are quite different. As the In coverage increases, a larger fraction of In resides in the adlayer, so the diffusion parameters slowly approach those for site-to-site hopping. For Sb there is evidence for immobile islands at higher coverages. This does not affect Ediff, but decreases D0 due to the smaller number of diffusion paths around the islands. The gradual change of In diffusion parameters with coverage is interrupted by an apparent phase transition at θ=0.16, where both Ediff and D0 peak sharply.
The Effect of Tungsten on the Nucleation and Growth of thin Aluminum Alloy Films
Authors: CAO Bea , David Theodore N. , Shin Hank , Fejes Peter , Hendrickson Les 
Published: March 2011

ABSTRACTA variety of alloying elements are currently being investigated for their effects on the mechanical properties and reliability of thin aluminum films. In the present study, scanning electron microscopy and transmission electron microscopy are used to study the nucleation and growth of Al-1.5wt%Cu and Al-1.5wt% Cu-0.2wt% W films. Differences in Microstructure, nucleation and growth behavior are observed and are explained in terms of changes in surface energies and atomic Mobilities.
In Situ Studies of Nitridation of Cu/Ti Thin Films Using Environmental Cell in Transmission Electron Microscopy
Authors: Sharma R. , Atzmon Z. , Mayer J. , Hong S. Q. 
Published: March 2011

ABSTRACTCo-deposited Cu/Ti thin films were heated at various temperatures in an ammonia ambient in an environmental cell fitted in to the column of transmission electron Microscope (TEM). The reaction dynamics was observed in situ and recorded on video using a TV camera with 1/30 sec. time resolution. The nitridation of titanium accompanied by nucleation and growth of copper particles started at 370°C. Ti2N formed at lower temperatures while TiN was formed above 400°C. The nucleation of crystals occurred simultaneously (within a Minute) throughout the film indicating no effect of electron beam on reaction process. The growth rate of copper particles was observed to vary slightly from one particle to another indicating varying growth rate for different facets.
The Commensurate Phase of Al Overlayers on the Si(111) Surfaces: STM Study of the γ-Phase Surface
Authors: Yoshimura M. , Takaoka K. , Yao T. 
Published: March 2011

ABSTRACTWe have elucidated the atomic structure of the γ-phase, which appears at 1ML coverage of Al on the Si (111) surface, using scanning tunneling Microscopy (STM). The structure is based on the 9×9 dimer-adatom-stacking fault (DAS) structure. Al atoms replace Si atoms in the second layer of the DAS Model. As a result, excess silicon atoms are produced during the formation of the γ-phase and migrate on the surface to form Monatomic-height islands. The area ratio of the upper and lower terraces is in good agreement with the proposed formation Mechanism.
The Evolution of Strain Relaxation Close to The Critical Thickness
Authors: Kidd P. , Fewster P.F. 
Published: March 2011

ABSTRACTHigh resolution X-ray diffraction space mapping has been used to follow the change in the distribution of residual strain and localised relaxation in low mismatched epitaxial layers. Using this new technique, we have obtained a series of diffraction space maps of partially relaxed epitaxial layers of In.1Ga.9As on GaAs. The layers have different thicknesses and hence different degrees of strain relaxation. The diffuse scatter close to the Bragg peaks provides information about the imperfect and distorted regions in the structure and this has allowed us to examine the extent and distribution of residual strain close to the dislocations. We have followed the evolution of local relaxation, which is confined initially to regions around isolated dislocations, through to the case of overlapping dislocation strain fields, leading to a more homogeneous strain field distribution and microscopic and macroscopic tilting of the layers.
A Study of the Defect Structure in GaAS1−xPx/GaAs AS x<0.25
Authors: Aragon G. , De Castro M.J. , Molina S.I. , Gonzalez Y. , Gonzalez L. , Briones F. , Garcia R. 
Published: March 2011

ABSTRACTThe defect structure of GaAsP layer grown by Atomic Layer Molecular Beam Epitaxy on (001) GaAs substrate has been studied by Transmission Electron Microscopy. The phosphorous content and the epilayer thickness have been changed below 25% and 1μm respectively. Three kinds of defect structure have been found: a) α-δ fringes at the interface for coherent epilayer, b) Misfit dislocation for thin epilayers and c) Multiple cracks normal to the interface and parallel to one <110> direction for thick epilayers.
Defect and Island Formation in Stranski-Krastanov Growth of Ge on Si (001)
Authors: Sakai Akira , Tatsumi Toru 
Published: March 2011

ABSTRACTWe have examined macroscopic island (Macro-island) formation in Stranski-Krastanov (SK) growth of Ge on Si (001) surfaces at various growth temperatures in molecular beam epitaxy (MBE). The nucleation mode of Macro-island formation was observed to be predominantly heterogeneous at medium growth temperatures less than 450°C, but homogeneous at high temperatures. In the heterogeneous Mode, Macro-island formation is mediated by particular V-shaped defects running preferentially along the <110> direction, which form as a result of coalescence of the well-faceted islands.
MBE Doping Kinetics - A Rate Equation Study
Authors: Bendi Shridhar , Venkatasubramanian R. , Dorsey Donald L. 
Published: March 2011

AbstractA rate equation model based on the master equation is developed for the study of MBE doping kinetics. The Model includes elementary surface processes such as adsorption, evaporation and migration of atoms. The Model is applied to the study of the surface segregation phenomenon during the In doping of Si. The doping studies were performed for the following growth conditions: T in the range 500 — 750°C; a growth rate of 1 μm/hr.; and a flux ratio, JIn/JSi equal to 2.0 × 10-4. The predicted sticking coefficient of In versus obtained shows excellent agreement with experiments. The sticking coefficient decreases with T due to surface segregation aided evaporation of In at higher temperature. The results of dopant depth profile also show excellent qualitative agreement with experiments. The surface segregation of In occurs due to a strong repulsive interaction between In and the host lattice. The results of this study show that there is a dopant depleted zone (DDZ) where the In concentration is lower than both the bulk and the top surface layer. The observed DDZ matches with that observed in experiments.
Computer Simulation of Surface Diffusion of Silver
Authors: Kumagai A. , Ogawa K. , Doyama Masao 
Published: March 2011

ABSTRACTThe binding energies to silver (111) surface of a silver ad-atom and its cluster have been calculated. The activation energies of motion of these ad-atom clusters, vacancies and divacancies on silver (111) surface have been calculated by use of n-body embedded atom potentials and molecular dynamics.
White-Beam Transmission Characterization of Texture in Mo Thin Films and Mo/W Multilayers
Authors: Vill Marc , MALHOTRA S. G. , Rek Z. , Yalisove S. M. , Bilello J. C. 
Published: March 2011

ABSTRACTSynchrotron white-beam (polychromatic) x-ray radiation was used in a transmission Laue study of texture in monolithic mo films and Mo/W Multilayers. High intensity synchrotron radiation permits x-ray diffraction study of mo specimens >100μm in thickness, while 6μm is the practical thickness limit for a transmission study using a rotating anode x-ray source. The transmission Laue technique permits the collection of preferred orientation data from several families of diffracting planes on one photographic exposure. Polychromatic x-rays facilitate collection of diffraction information from a range of planar orientations without altering the orientation of the sample with respect to the incident x-ray beam. The texture information from a 35μm thick monolithic mo film and a 31μm thick multilayer of mo and W is presented. Two-fold symmetry seen in the {211} plane diffraction ring of the multilayer demonstrated both an in-plane and out-of-plane texture with a <110> growth direction. Three fold symmetry seen in the {310} and {222} plane diffraction rings of the monolithic mo film demonstrated both in-plane and out-of-plane texture which suggests a <111> growth direction.
Effect of Buried Surface Structure on Solid Phase Epitaxy of GE on SI (111)-7×7
Authors: Hellman Olof C. 
Published: March 2011

ABSTRACTWe study the crystallization of a thin film of amorphous Ge deposited at room temperature on Si (111). Features of the silicon surface buried beneath the Ge film are shown to affect the rate of crystallization. In particular, solid phase epitaxy is observed to be enhanced at surface steps and defects in the surface reconstruction. It is further shown that one-dimensional crystallization patterns can be caused by impurity-Mediated crystallization. Precipitates of an impurity rich phase migrate in the plane of the film, leaving behind a crystalline trail. The Migration path of these precipitates is also dependent on the buried surface structure.
Growth, Structure, and Thin Film Stress in TiAl AND Ti3Al FILMS
Authors: Chinmulgund M. , Inturi R. B. , Barnard J. A. 
Published: March 2011

ABSTRACTThin films of Ti, Al, TiAl and Ti3Al were deposited by dc magnetron sputtering onto 2” dia. oxidized Si<111> wafers and their mechanical properties were studied by measuring the internal stress in the films. Ti and Ti3Al films show hexagonal structure with preferred orientation in the (0002) direction. TiAl is tetragonal, nanocrystalline, and (111) oriented; Al is random fee polycrystalline in nature. Young's Modulii of thin films of these materials were calculated from the stress temperature plots. The E values of TiAI and Ti3Al thin films were found to be significantly higher than those of the bulk Materials.
Using Zeolites as Substrates for Diamond Thin Film Deposition
Authors: Kwan Michael C. , Gleason Karen K. 
Published: March 2011

ABSTRACTZeolites have been used as a potential substrate for CVD diamond deposition. By saturating the pore channels of a silicalite crystal, which are spaced approximately 10 Å apart, with hydrocarbon seeds to induce and control nucleation, films have been grown in a hot filament chemical vapor deposition (HFCVD) system under standard deposition conditions, using acetone as the carbon source. The hydrocarbons used were adamantane, naphthalene, anthracene, 2,3-benzanthracene, and l,2:5,6-dibenzanthracene. To enhance nucleation, a high pressure pre-deposition period was used initially.Characterization of these films through electron diffraction and Auger electron spectroscopy indicates that polycrystalline β-SiC imbedded in an amorphous matrix is initially formed and large, well faceted diamond crystals are subsequently nucleated.
X-ray Photoelectron Spectroscopy of the Interface Between Diamond Films and Tantalum Substrates
Authors: Waitew M.M. , Ismat Shah S. 
Published: March 2011

ABSTRACTDiamond films were deposited in a microwave plasma chemical vapor deposition (MPCVD) system on Ta substrates using a mixture of hydrogen and methane gases. The films were grown for varying lengths of time to provide samples with no diamond growth to a continuous diamond film. These films were analyzed using X-ray photoelectron spectroscopy (XPS) in order to understand the time dependent interactions between the substrate and the incoming carbon flux. Photoelectron peaks in the Ta 4f, C Is and Ols regions have been analyzed. In the initial stages of growth, a layer of carbide forms on the substrate. As the substrate becomes supersaturated with carbon, graphite starts to form on the surface. A diamond peak begins to appear after about 30 Minutes of deposition.
Development of Anisotropic GaAs (001) Surface Morphology During Molecular Beam Epitaxial Growth
Authors: Pidduck Allan J. , Smith G.W. , Keir A.M. , Whitehouse C.R. 
Published: March 2011

ABSTRACTWe have studied the development of a microscopically ridged [110] Morphology during (001) GaAs Molecular beam epitaxy, as a function of layer thickness and growth temperature. The ridge slopes are consistent with the [110] separation required to incorporate a majority of adatoms by step-flow growth. Thus step-flow can be a dominant growth mode even on nominally on-axis (singular) substrates. With increasing epilayer thickness, the ridge slopes, and surface step density, remain approximately constant, while the ridge spacings, and therefore roughness amplitude, increase steadily.
Structure and morphology of Clean and Magnesium - Dosed Sapphire Surfaces
Authors: Yu Yan , Lad R.J. 
Published: March 2011

ABSTRACTThe structure and morphology of r-axis (1012) and c-axis (0001) sapphire (a-Al2O3) surfaces were studied with Low Energy and Reflection High Energy Electron Diffraction (LEED and RHEED) and Atomic Force Microscopy (AFM). Following heat treatments at 1000°C in 5×10-7 torr O2, both surfaces exhibited (1×1) diffraction patterns. Regular step-terrace structure was observed on the (1012) surface with the AFM, but no step structure was visible on the (0001) surface. The initial growth of magnesium overlayers dosed onto the (1012) surface at 25°C in ultra-high vacuum was monitored with RHEED and the chemical interactions at the Mg / Al2O3 interface were characterized with X-ray Photoelectron Spectroscopy (XPS). During the initial deposition, very little interaction between mg and the Al2O3 substrate occurs and a very abrupt interface is formed. At larger mg doses, a textured polycrystalline mg overlayer is produced. Annealing the mg film above 300°C causes some oxidation of mg at the Mg / Al2O3 interface, but most of the mg desorbs from the surface.
Deposition and Properties of Epitaxial Ferrite Thin Films
Authors: Phillips Julia M. , Van Dover R. B. , Gyorgy E. M. , Marshall J. H. 
Published: March 2011

ABSTRACTWe have grown thin films and multilayers of several ferrite materials with the spinel structure by pulsed laser deposition of stoichiometric targets. Epitaxial films can be grown on a variety of substrates including MgO, Al2O3, MgAl2O4, Y-stabilized ZrO2 (YSZ) and SrTiO3. Films on Mg- and Al-containing substrates have a low saturation Magnetization, Ms, while films on YSZ and SrTiO3 exhibit bulk values of Ms. The anisotropy can be lowered by a post growth anneal, resulting in a film with a permeability of 28.
Growth and Characterization of Silicon-Germanium Films on Oxide by VLPCVD/PE-VLPCVD
Authors: Tsai Julie A. , Reif Rafael 
Published: March 2011

ABSTRACTResults of Si1-xGex deposition on oxide-coated Si substrates using a PE-VLPCVD (Plasma-Enhanced Very-Low-Pressure Chemical Vapor Deposition) reactor are presented. Thin layers of poly-Si1-xGex deposited with SiH4 and GeH4 at ≤ 600°C had low C and O levels. Two growth modes were examined at 500°C: plasma-initiated thermal growth (VLPCVD) and full plasma-enhanced deposition (PE-VLPCVD). In both cases, Ge incorporation increases sublinearly with gas ratio, growth rates increase with Ge content, and the transition temperature between polycrystalline and amorphous deposition is lower for Si1-xGex than Si. On the other hand, compared to thermal growth, plasma-enhanced deposition promotes not only higher growth rates but also improved structural properties such as smoother surface Morphology, More columnar and oriented grains, and the unique feature of direct deposition onto oxide.
The As-Grown Microtopologies of Solution Grown GaAs (001) Vicinal Surfaces
Authors: Marek T. , Strunk H.P. , Bauser E. , Lu Y.C. 
Published: March 2011

ABSTRACTThe observations of the as-solution-grown GaAs (001) vicinal surfaces yield three kinds of Microtopologies. Each of them develops in a certain range of growth temperature. In a low temperature range (492° C…600° C) we observe parallel growth steps with heights of one Monolayer. In a medium range, a network consisting of two sets of growth steps with larger heights is observed. At high growth temperatures (780° C…850° C) we find growth surfaces that are atomically rough. IMplications of these findings for modelling the crystal growth will be discussed.
Atiomiic Scale Interface Structure of In0.2Ga0.8As/GaAs Strained Layers Studied by Crosssectional Scanning Tunneijng Microscopy
Authors: Zheng J. F. , Salmeron M. B. , Weber E. R. 
Published: March 2011

AbstractA molecular beam epitaxy-grown In0.2Ga0.8As/GaAs strained layer structure has been studied by scanning tunneling microscopy in cross-section on the (110) cleavage plane perpendicular to [001] the growth direction. Individual Indium atoms were differentially imaged in the group III sublattice, allowing a direct observation of the interface roughness due to the indium compositional fluctuation. In the In0.2Ga0.8As layers, Indium atoms are found in clusters preferentially along the growth direction with each cluster containing 2-3 indium atoms. Indium segregation induced asymmetrical interface broadening is studied on an atomic scale. The interface of In0.2Ga0.8As grown on GaAs is sharp within 2-4 atomic layers. The interface of GaAs grown on In0.2Ga0.8As is found to be broadened to about 5-10 atomic layers. The atomic scale fluctuation due to indium distribution is about 20 Å along the interface in this case. We conclude that clustering and segregation are the main reason for the In0.2Ga0.8As/GaAs interface roughness.
Dissociation of Misfit Dislocations in GeSi/{111}Si Interfaces
Authors: Ernst Frank 
Published: March 2011

AbstractThe accommodation of lattice mismatch is studied in Ge0.15Si0.85 layers grown epitaxially on {111}-oriented Si substrates by chemical vapor deposition (CVD) at 1100°C. Weak beam dark field microscopy reveals a regular misfit dislocation network, which resembles the honeycomb network of edge-type dislocations anticipated by the O-lattice theory. In contrast to the latter, however, the real network exhibits extended nodes where the misfit dislocations dissociate into misfit partial dislocations. Between the partials, high resolution transmission electron microscopy (HRTEM) reveals intrinsic and extrinsic stacking faults. Owing to the presence of these stacking faults, three different atomistic structures of the GeSi/Si interface coexist and compete for the interfacial area according to their energy. The observed configuration is shown to minimize the total energy of the interface.
Observation of Open-Ended Stacking Fault Tetrahedra in Si0.85Ge0.15 Grown on V-Grooved (001) Si and Planar (111) Si Substrates
Authors: Howard David J. , Paine David C. 
Published: March 2011

AbstractA new strain relief mechanism was observed in thin films of Si0.85Ge0.15 grown by RTCVD (rapid thermal chemical vapor deposition) on patterned (001) and planar (111) Si substrates. The (001) Si substrates were lithographically patterned and anisotropically etched to produce a line pattern of V-shaped grooves running in the [110] direction where the walls of the grooves were the {111} crystal planes lying in the [110] zone. Cross-section and plan-view TEM (transmission electron microscopy) studies revealed the presence of open ended stacking fault tetrahedra in strained-layer Si0.85Ge0.15 grown both on (111) Si wafers and the {111} sidewalls of the patterned (001) Si wafers. No defects were observed in the (001) portions of the films grown on non-planar substrates.
In-Situ 1Mev Tem and Hrem Study of the Deformation and the Transformation of Symmetrical Tilt Grain Boundaries in Ge and Si.
Authors: Thibault Jany. , Baillin X. , Pelissier J. , Putaux J.L. , Michaud H.M. 
Published: March 2011

AbstractThe evolution under deformation of symmetrical GBs in Si and Ge has been studied both by in-situ TEM and HREM. The influence of the strain conditions (tension or compression) on the final structure through the entrance of different types of dislocations will be discussed. The influence of the deformation temperature on the multiplicity of the structures has been observed in a particular range of misorientation angles.
Atomistic Calculations and Hrtem Observations of an [001] Tilt Boundary in Rutile
Authors: Lee W.-Y. , Bristowe P.D. , Solorzano I.G. , Vandersande J.B. 
Published: March 2011

AbstractThe equilibrium atomic structure of the ∑=15 36.9° (210)[001] tilt boundary in rutile (TiO2) has been computed using an ionic shell model and compared to a high-resolution electron microscope image of the same boundary using image simulation. The lowest energy structure of the boundary is characterized by an in-plane translation of a/6[120] relative to the mirrorsymmetric CSL configuration in agreement with the electron microscope observations.
Computer Simulation of Tensile Deformation of Titanium Small Single Crystals with Stacking Faults
Authors: Aoshima M. , Kusube T. , Ida J. , Doyama Masao 
Published: March 2011

AbstractSmall single crystals of titanium with and without stacking faults have been pulled by use of the molecular dynamics method. The tensile axis was [0001] and the stacking fault was introduced on (0001) pianes. The yield stress was higher in the crystal with stacking faults. The deformation was complicated in the crystal with stacking fault. Dislocations were created near the tip of a crack and moved on (1122).