bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synchrotron White Beam Topography Studies of Residual Stress in SiC Single Crystal Wafers with Epitaxial Thin Films
Authors: Huang W. , Wang Q. , Dudley M. , Chiang F. P. , Parsons J. , Fazi C. 
Published: April 2011

ABSTRACTThe residual stress in a 6H-SiC wafer with a 3C-SiC epitaxial overlayer is determined by the technique of Synchrotron white beam x-ray topography (SWBXT). The short wavelength and high energy attributes of synchrotron radiation are exploited to very accurately determine the wafer curvature. Different approaches including absorption edge contour (AEC) mapping, multiple diffraction line (MDL) analysis and diffracted x-ray beam divergence (DXBD) analysis in both transmission and reflection geometry are demonstrated. The residual stress distribution is calculated from the wafer curvature measurement.
Reciprocal Space Analysis of the Initial Stages of Strain Relaxation in SiGe Epilayers
Authors: Lee S. R. , Floro J. A. 
Published: April 2011

ABSTRACTMetastable SiGe films were grown by MBE on Si (001) substrates and annealed to promote varying degrees of partial relaxation. X-ray diffraction reciprocal-space analysis was then used to monitor the structural evolution of the displacement fields of the dislocation array with increasing misfit density. The diffuse-x-ray-scattering patterns of the dislocated heterolayers were compared with lineal-misfit densities determined by defect etching, leading us to develop a geometric model which provides a framework for understanding the early-stage evolution of the displacement fields of the dislocation array, and which also explicitly links diffuse x-ray intensity to misfit density. At low misfit density, the diffuse intensity arises from two-dimensional displacement fields associated with single-nonoverlapping dislocations. As misfit density increases, the displacement fields of individual dislocations increasingly overlap producing three-dimensional displacements. The evolving diffuse intensity reflects the transition from 2-D to 3-D displacement fields. Finally, it is demonstrated that the diffuse x-ray intensity of the strained epilayer can be used to accurately measure lineal misfit-dislocation densities from 400 to 20,000 lines/cm.
Defect Structure of Cu-Rich and In-Rich Chalcopyrite CuInSe2 Films Grown on GaAS
Authors: Hellman Olof , Tanaka Shun-Ichiro , Niki Shigeru , Fons Paul 
Published: April 2011

ABSTRACTUsing Transmission Electron Microscopy, we examine the defect structure of Cu-rich and In-rich CuInSe2 films grown by Molecular Beam Epitaxy on GaAs (100) substrates. A surprisingly high density of cation sublattice stacking faults on (001) planes are observed in the Cu-rich films. Because these stacking faults are extremely flat and extend thousands of Ångstroms over the surface, and because they are not observed in other, non-Cu-rich films, we argue that they are a consequence of a surface structural change during growth, induced by the excess Cu. Two other types of defects are also observed: near the CuInSe2/GaAs interface, there is a high concentration of dislocations, stacking faults and domain boundaries. In the In-rich films, stacking faults and twin-type defects on {112} planes extend throughout the thickness of the grown film.
Technical Applications of Nanocrystalune Materials
Authors: Schulz R. 
Published: April 2011

AbstractAfter discussing various applications of nanocrystalline solids which are presently under development, this paper describes in more detail the potential use of nanocrystalline materials for the production of sodium chlorate, a paper bleaching agent. The technology and advantages of using nanocrystalline solids as cathode material for this electrochemical process are discussed. The paper concludes by presenting the world market and potential savings associated with the use of this new technology.
Ti-Zr-Ni Quasicrystals: Structure and Hydrogen Storage
Authors: Stroud R. M. , Viano A. M. , Majzoub E. H. , Gibbons P. C. , Kelton K. F. 
Published: April 2011

AbstractTitanium-based icosahedral phases constitute the second largest class of quasicrystals. In contrast with other Ti-based icosahedral phases (i-phases), Ti-Zr-Ni i-phases are well ordered and their formation is inhibited by the presence of Si and O, elements that stabilize the Ti-3d transition metal quasicrystals. We present x-ray and DSC data that suggest that Ti-Zr-Ni i-phases form a different class of titanium-based quasicrystals that are closely related to the MgZn2 Laves phase. The DSC data also suggest that the i-phase may be stable in these alloys. The ability of Ti-Zr-Ni i-phases to absorb up to 62 atomic % of hydrogen is presented and discussed. This opens new avenues of investigation of the structure and dynamics of quasiperiodic phases using elastic and inelastic neutron scattering and nuclear magnetic resonance and may point to potential uses for quasicrystals in hydrogen storage applications.
Tem Investigation and Hardness Improvement of A N+ Implanted Al-Alloy
Authors: Serventi A.M. , Vittori Antisari M. , Guzman L. , Miotello A. 
Published: April 2011

AbstractThe surface modification induced by nitrogen ion implantation on the Al-alloy 7075 has been studied with the aim of understanding the microstructural evolution and the phase separation during the implantation process. 150 keV N2+ ions have been implanted at different temperatures from 373 K to 473 K, with a current density of 5–15 µA/cm2 on previously polished samples. The implanted dose was in the range 1 × 1017 N/cm2 - 5 × 1017 N/cm2. Vickers micro-hardness tests and friction coefficient measurements show a real improvement in the mechanical behaviour of the alloy after the treatment.TEM observations of specimens treated at low temperature with different ion dose have been carried out at 200 kV on cross-sectional samples, prepared by ion beam milling. First results show the presence of small AlN hexagonal precipitates whose evolution is followed as a function of the implanted dose.
Evolution of the Nanostructure of Giant Magnetoresistance Heterogeneous Alloys CoxAg1-x Upon Annealing
Authors: Regnard J. R. , Revenant-Brizard C. , Dieny B. , Mevel B. , Mimault J. 
Published: April 2011

AbstractHeterogeneous alloys CoxAg1-x with atomic concentrations x=0.20 and 0.35, presenting giant magnetoresistance properties, have been studied by Total Electron Yield X-ray absorption spectroscopy at liquid nitrogen temperature at the Co K edge after annealings at various temperatures. For both sample concentrations, the Co atoms are mainly in small filament agglomerates for the as-deposited and low temperature annealed samples (T<150°C). In this temperature range, the local Co atomic environment is very stable and disordered. A structural change has been detected by XANES and EXAFS analysis between the 250 and 400°C annealings. After a 400°C annealing during 10 min, the nanostructures evolve towards larger, more compact and well ordered granules. The Co-Co distance varies from 0.246 to 0.248 nm as the annealing temperature increases indicating that the small filament-shaped agglomerates are under strain in the Ag matrix. The Debye-Waller factor of the Co0.35Ag0.65 samples decreases continously as the annealing temperature increases, as this factor drops suddenly after a 250°C annealing for the Co0.20Ag0.80 sample. The Co agglomeration is steadily larger for the Co0.35Ag0.65 sample than for the Co0.20Ag0.80 one. The Co-Ag contribution is negligible for the Co0.35Ag0.65 sample, as it represents approximately one third of the nearest neighbors for the Co0.20Ag0.80 sample from the as-deposit up to a 250°C annealing stage.
Grain Growth Impediment of Fe-Based Nanocomposites During Heat Treatment at Elevated Temperature
Authors: Huang B. , Perez R.J. , Lavernia E.J. 
Published: April 2011

AbstractCryogenic ball milling of Fe-10 wt.%Al in liquid argon is shown to produce a nanocrystalline microstructure with high thermal stability against grain growth. The experimental evidence suggests that this stability may originate from the presence of fine γ-Al2O3 particles which pin the Fe grain boundaries. In contrast, Fe3O4 particles formed during cryomilling of Fe in liquid nitrogen were not able to impede grain growth during consolidation at 823 K. The interactions between the γ-Al2O3 particles and the grain boundaries during growth may be described by Gladman's theory. Additional stabilization against grain growth may have been provided by the presence of Al at the Fe grain boundaries. Following annealing at 1223 K, the grain size of the Fe-10 wt.%Al powders cryomilled in liquid argon was 13.3 ± 7.9 nm, but it exceeded 1700 nm following annealing at 1373 K. The loss of nanocrystalline structure may be attributed to the Ostwald ripening of γ-Al2O3 particles, resulting in abnormal grain growth.
In-situ Studies of a Novel Sodium Flame Process for Synthesis of Fine Particles
Authors: Steffens Kristen L. , Zachariah Michael R. , Dufaux Douglas P. , Axelbaum Richard L. 
Published: April 2011

AbstractThis study focuses on the optical characterization of a novel method of forming nanoscale titanium and boron particles, which can be used to form ceramic precursors such as TiB2. TiCl4 or BCl3 reacts with heated Na vapor in a counterflow diffusion flame reactor. After Na strips the Ti or B of its Cl atoms, nanosize Ti or B particles form and become encased in NaCl, which helps to prevent agglomeration and oxidation. The two-dimensional spatial distribution of the Na dimer has been optically interrogated using planar laser-induced fluorescence (PLIF) to clarify the influence of the concentration distributions and transport on particle formation rates.
Low Temperature Silicides for Poly-Silicon Thin Film Transistor Applications
Authors: Sarcona G. T. , Hatalis M. K. 
Published: April 2011

AbstractThin films of cobalt, nickel, and tungsten were sputtered on three types of silicon materials to explore their potential for use as silicides in thin film transistor technologies for active matrix liquid crystal displays. The metals were sputtered onto single-crystal, polycrystalline, and amorphous silicon. The metals were annealed in vacuum after deposition over temperatures ranging from 250°C to 750°C. The sheet resistance of the resulting silicide films was measured using a four point probe apparatus. Cobalt silicides with sheet resistance of less than 4 Ω/ were formed at 600°C. Nickel produced films with sheet resistance below 10 Ω/▪ at 350°C, though the surface was required to be vacuum-clean. In this study, tungsten did not produce silicides. Surface preparation has been found to be an important factor in tungsten and nickel silicidation.
Interface Stability of Ti(Sil−yGey)2 and Si1−x Gex Alloys
Authors: Aldrich D. B. , D'Heurle F. M. , Sayers D. E. , Nemanich R. J. 
Published: April 2011

AbstractThe stability of C54 Ti(Si1−yGey)2 films in contact with Si1−xGex substrates was investigated. The titanium germanosilicide films were formed from the Ti − Si1−xGex solid phase metallization reaction. It was observed that Ti(Si1−yGey) 2 initially forms with the same germanium content as the Si1−x Gex substrate (i.e., y = x). Following the initial formation of TiM2 (M = Sil−yGey), silicon and germanium from the substrate diffuse into the TiM2 layer, the composition of the TiM2 changes, and Si1−z Gez precipitates form along the TiM2 grain boundaries. The germanium content of the Ti(Sil−y Gey)2 decreases, and the Sil−z Gez precipitates are germanium rich such that y < x < z. This instability of the TiM2 film and the dynamics of the germanium segregation were examined using the Ti-Si-Ge ternary equilibrium diagram. The relevant region of the ternary diagram is the two phase domain limited by a Si-Ge solid solution and a TiSi2 − TiGe2 solid solution. In this study first approximation Ti(Sil−y Gey)2 -to- Sil−xGex tie lines were calculated on the basis of classical thermodynamics. The tie line calculations indicate that for C54 Ti(Sil−yGey)2 to be stable in contact with Sil−xGex, the compositions of the two phases in equilibrium must be such that y < x. The specific compositions of the two phases in equilibrium depend on the temperature and the relative quantities of the two phases. The dynamic processes by which the Ti(Si1−yGey)2/Si1−x. Gex, system progresses from the as-formed state (y = x) to the equilibrium state (y < x) can be predicted using the tie line calculations.
Silicidation Strategy Of Sub-0.1 μm Junctions for Deep Submicron Devices
Authors: Tsai Jiunn-Yann , Osburn Carlton M. , Hsia Steve L. 
Published: April 2011

AbstractTwo major concerns for silicidation of ultra-shallow junctions, namely the silicon-consumption- induced junction leakage and the series resistance increase, were compared among conventional post-junction-silicide (PJS) contact, silicide-as-a-diffusion-source (SADS) contact, Silicon-On-Insulator (SOI) contact, and elevated-source-drain (ESD) contact. Even though we found that ESD contacts would be the ultimate solution for both problems, SOI and SADS contacts provide better resistance to silicon-consumption-induced series resistance increase over conventional PJS contact because both are able to maintain a high dopant concentration at the silicide/silicon interface and thus a low specific contact resistivity. While there is no junction leakage concern for SOI contact, the SADS junction is also distinguished by low leakage owing to its lack of implant damage in the silicon substrate and uniformly doped junction along the silicide/silicon interface contour. MOSFET devices with SADS source/drain were demonstrated with quarter-μm technology. Epitaxial cobalt disilicide (CoSi2) was formed using the Ti/Co bilayer technique as a diffusion source. While both ESD and SOI processes still suffer from process complexity, integration and materials issues, we conclude that SADS contacting is a promising alternative for deep submicron devices.
Magneto-Transport Properties of Epitaxial Iron-Silicides
Authors: Goncalves-Conto S. , Onda N. , Von Känel H. 
Published: April 2011

AbstractThe phase-breaking time τφ'. in thin α-FeSi2 films was obtained from the analyses of the lowtemperature magnetoresistance (MR). The films were grown by molecular beam epitaxy (MBE) on Si(111) and capped with epitaxial Si. The MR behavior is interpreted in terms of two-dimensional (2D) weak localization with strong spin-orbit interaction and electron-electron interaction (EEI). By fitting the MR data we obtained the temperature dependence of τφ. The results indicate the phase-breaking time to vary as T− over a large temperature range from 1.7 to 15 K, in agreement with the dependence predicted by the EET in 2D systems.
Characterization of Ultra-Thin PtSi Films for Infrared Detectors
Authors: Bender H. , Roussel P. , Kolodinski S. , Torres A. , Donaton R. A. , Maex K. , van der Sluis P. 
Published: April 2011

AbstractTransmission electron microscopy and grazing incidence X-ray diffraction are used for the structural characterization of ultra-thin PtSi layers on (100) silicon prepared by a two-step rapid thermal annealing process. The roughness of the layers is investigated with atomic force microscopy. Two deposition techniques for the initial Pt layer are compared.
Synchrotron Radiation Studies of Platinum Silicide Thin Films
Authors: Sham T. K. , Naftel S. J. , Bzowski A. , Das S. R. , Xu D.-X. , Heald S. M. , Brewe D. , Kuhn M. 
Published: April 2011

AbstractPtSi thin films prepared by UHV sputter-deposition procedures on n-type Si(100) wafers have been studied with the following techniques: (a) X-ray absorption fine structure spectroscopy at the Si K-edge, Si L2,3-edge, and Pt L3-edge; (b) X-ray reflectivity at photon energies below and above the Pt L3-edge threshold and (c) Photoemission. These techniques provide valuable information about the electronic structure, morphology, local structure, thickness, density and roughness, and surface and interface properties of the films. Preliminary results from the application of these techniques to the study of several PtSi thin films (with thickness from several hundreds to thousands of Å) are reported.
Characterization of Atmospheric Impurities in Tungsten Silicide Films by Secondary Ion Mass Spectrometry (SIMS)
Authors: Mitha Salman , Sams David B. 
Published: April 2011

AbstractConcentrations of atmospheric impurities in tungsten silicide films and impurity areal densities silicide / polysilicon interface can usually only be measured using Secondary Ion Mass Spectrometry (SIMS). Normally these measurements are made using a Cs+ primary beam with negative secondary ions being monitored. This mode is used to achieve the best possible detection limits. However the Relative Sensitivity Factors (RSFs) used to quantify the impurities, as well as the reference matrix signal, change dramatically in going from one matrix to the other. These changes affect the quantification of the impurities at the interface. An alternate mode of analysis would be to use the Cs+ primary beam and monitor MCs+ ions, where M is the impurity, because these ions typically have less matrix dependent RSFs. We measure carbon and oxygen in a tungsten silicide film on polysilicon using both modes of analysis. Preliminary data indicates that we have determined the absolute accuracy of interface areal density to within a factor of 2.2 for oxygen and to within a factor of 1.5 for carbon.
Effect of the Volume Variation on the Superconductivity of TaSi2
Authors: Keller N. , Laborde O. , Gottlieb U. , Madar R. 
Published: April 2011

AbstractTaSi2, and NbSi2 are superconductors below 353 mK and 130 mK respectively. These compounds, like VSi2 which is not superconducting down to 100 mK, crystallise in the C40 structure. They differ by a slight variation of lattice parameters.We have systematically investigated the superconducting properties of several samples of TaSi2 by magnetic and resistive measurements. A small difference on Tc is observed for the same crystal by the two techniques. Several explanations are presented for this result.We also report a change of Tc under pressure in good agreement with those resulting of the volume variation for the two C40 superconductors previously studied.
Formation and Relaxation of Ni(Au) Disilicide
Authors: Mangelinck D. , Ga P. , Gay J. M. , Pichaud B. 
Published: April 2011

AbstractThe formation and the relaxation of NiSi2 films with and without Au are examined by scanning electron microscopy, X-ray diffraction and Rutherford backscattering spectrometry. We studied the solid state reactions between a Ni(7 at.% Au) thin film and a Si substrate which occurs during the solid phase epitaxy before the formation of NiSi2. We show that the addition of Au to the Ni film drastically affects the silicides formation: Ni2Si and NiSi appear simultaneously and the nucleation temperature of NiSi 2 is lowered. The solubility of Au in the three silicides is limited which induces a precipitation of Au. Depending on temperature this precipitation takes various forms: Au enriched surface layer or Au clusters at inner interfaces. The films lattice parameters both parallel and perpendicular to the interface are also measured and compared to the lattice parameters of bulk samples which have been made by solidification from the melt. The relaxation modes are deduced from these measurements.
Post Titanium Silicide Processing
Authors: Grynkewich G. , Ilderem V. , Miller M. , Ramaswami S. 
Published: April 2011

AbstractDecreasing contact dimensions coupled with the need for planarization to accommodate multiple layers of metal have created many challenges for the contact etch module. For example, contact etch processes are often required to stop on thin titanium silicide while at the same time forming high aspect ratio, straightwalled contacts. In this paper, the impact of various dielectric compositions and contact etch process parameters on etch profile, selectivity, and contact resistance is presented for the formation of high aspect ratio, submicron contacts to thin TiSi2 layers. The etch profile is formed by RIE using a mixture of CHF3 and various amounts of CF4. Surprisingly, the sidewall angle and selectivity to silicide showed little dependence on the percent CF4. Contact resistance measurements, however, varied greatly with percent CF4 and contact aspect ratio. The variation of contact resistance with etch chemistry was attributed to a variation in the extent of fluorocarbon polymer film formation, which in turn depends on the ratio of carbon to fluorine in the plasma. Finally, post contact etch treatments were examined for efficiency in removing the polymer films from the high aspect ratio contacts.
Controlled Grain Size and Location in GE Thin Films on Silicon Dioxide by Low Temperature Selective Solid Phase Crystallization
Authors: Yang C. M. , Atwater Harry A. 
Published: April 2011

AbstractSelective solid phase crystallization for control of grain size and location in polycrystalline thin Ge films on amorphous silicon dioxide substrates is described. The approach consists of selective solid phase crystal nucleation via an alloy reaction at predefined nucleation sites, which consist of metal islands deposited on top of the amorphous Ge film, followed by lateral solid phase epitaxial growth. Grain sizes as large as 30 μm have been achieved in 50 nm thick Ge films at temperatures less than 475 °C.
Properties and Fracture Resistance of Thin Polycrystalline Aluminum Films on Sapphire Substrates
Authors: Moody N. R. , Medlin D. , Guthrie S. , Hwang R. Q. , McCarty K. F. 
Published: April 2011

AbstractWe employed nanoindentation, continuous microscratch testing, and high resolution TEM to determine the effect of structure on the properties and resistance to fracture of thin polycrystalline aluminum films deposited onto single crystal sapphire substrates at 25°C and 250°C. These films had a nominal thickness of 90 nm and a grain size of 160 nm. The elastic and plastic properties were similar for both films. The elastic moduli superimposed, increasing from bulk aluminum values at the surface to sapphire values at the interface. Hardness values also superimposed, but were constant through the film thickness at a value between aluminum and sapphire. In contrast, susceptibility to fracture varied markedly between the films with the 25°C film exhibiting abrupt failure along the film-substrate interface while the 250'C film gave no indication of fracture in the film, along the interface, or in the substrate under the conditions tested.
Giant Magnetoresistivity in Electrochemically Produced Cobalt-Copper Multilayers
Authors: Lashmore David S. , Hua Susan Z. 
Published: April 2011

AbstractThe electrodeposition of cobalt-copper multilayers will be described and the dependence of their magnetoresistivity on layer thickness and deposition parameters will be presented. For a wide variety of layer thicknesses electrochemically produced Co(Cu)-Cu thin polycrystalline layered alloys exhibit a giant magnetoresistivity (GMR). Further, upon annealing, the materials undergo a combination of grain growth and grain boundary diffusion. At certain conditions, this phenomena is believed to lead to a break up of the layered structure so that a magnetostatic coupling occurs and contributes to the GMR behavior. It is further shown that, by careful control of the deposition parameters, a quasilinear GMR response (low sensitivity) can be created over a large magnetic field or, conversely, a high sensitivity material can be grown, although at the sacrifice of introducing hysteresis in the response curve. The major deposition parameter affecting this behavior is mass transport in the electrolyte; however, substrate grain size, layer spacing and annealling history also play an important role.
Evolution of the Surface Structure of CVD Tungsten During Annealing
Authors: Briant C. L. , Wilson R. H. , Bigio L. , Morris W. G. 
Published: April 2011

AbstractThis paper reports a study in which a rough tungsten surface was prepared by chemical vapor deposition of tungsten on a tungsten ribbon. The samples were then heated to study the smoothing behavior of the rough surface. The results show that at 1600°C the surface becomes smooth after approximately five to ten hours. At 2400°C the surface becomes smooth within 15 minutes.