bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic Roughening of Fe/Fe(100) Epitaxial Thin Films
Authors: Bartelt M.C. , Evans J.W. 
Published: April 2011

ABSTRACTWe model kinetic roughening during Fe(100) homoepitaxy, where the formation of mounds with selected slope has been observed. Our model incorporates irreversible nucleation and growth of two-dimensional square islands in each layer, and a step-edge barrier to diffusive downward transport (which exceeds the barrier, Ed, to terrace diffusion by ESch). We estimate that ESch≈45meV compared with Ed≈450meV. To reproduce observed behavior, it is also essential for the model to incorporate "downward funneling" of depositing atoms to four-fold hollow adsorption sites, as this controls slope selection. Finally, we discuss model predictions for the non-monotonic temperature dependence of kinetic roughening.
A Molecular Dynamics Study of the Terminal Zr(Ni) Solid Solutions
Authors: Cleri F. , Mazzone G. , Rosato V. 
Published: April 2011

AbstractThe Zr terminal portion of the Zr-Ni phase diagram has been evaluated by means of a many-body tight-binding potential. The internal energy curves of the Zr(Ni) solid solutions at T=300 K have been calculated by Molecular Dynamics simulations. These curves exhibit positive values, contrary to former empirical phase diagram calculations. Implications of these results relevant to the problem of amorphization in metallic systems by solid-state reactions are discussed.
APFIM Studies of Nanocrystallizations of Amorphous Alloys
Authors: Hono K. , Zhang Y. , Inoue A. , Sakurai T. 
Published: April 2011

AbstractThis paper reports recent atom probe analysis results of Fe-Zr-B(-Cu) and Al-Ni-Ce(-Cu) amorphous alloys, in which nanocrystalline microstructures develop by primary crystallization. In these alloy systems, enrichment of slow diffusing solute was found at the interfaces between primary crystals and amorphous matrix during the nucleation and growth stage. In the case of ternary Fe-Zr-B, no evidence for compositional heterogeneities were found prior to the onset of crystallization reaction. On the other hand, clustering of Cu atoms was observed in quaternary Fe-Zr-B-Cu alloy prior to the crystallization reaction. In the ternary Fe-Zr-B alloy, nucleation sites seem to be provided by the quenched-in nuclei which were observed as medium range ordered (MRO) domains by HREM. In the as-quenched Al-Ni-Ce(-Cu) alloy, compositional fluctuations were present from the as-quenched state. These observations suggest that nuclei for primary crystallization are provided in various forms such as MRO domains, solute clusters and compositional heterogeneities.
Crystallization of Sputter Deposited Ti-Al Amorphous Alloy
Authors: Ohnuma M. , Abei T. , Onodera H. 
Published: April 2011

AbstractThe crystallization process of Ti-Al amorphous alloy has been studied by X-ray diffraction, small-angle neutron scattering and high resolution electron microscopy. In the early stage of crystallization of a thick sample with 55at%Al, a metastable hcp(α, α2) phase appeares. For a thin sample with 52at%Al, a new metastable phase having primitive tetragonal symmetry is found in the early stage of crystallization. The lattice parameter of this tetragonal phase is a=c=0.69nm. The prototype structure which has the same atomic arrangement as this phase is only Cu4Pd type structure (P42/m) in the Peason's Handbook.
Microstructure of Extremely Fine Lamellae in a TiAl Base Alloy Studied by High-resolution Electron Microscopy
Authors: Abe E. , Kumagai T. , Nakamura M. 
Published: April 2011

AbstractAn extremely fine lamellar structure formed in a Ti-48at.%Al alloy, which was heat treated in the high-temperature α-Ti (disordered hcp) single phase field (1683K), followed by ice water quenching, has been examined by high-resolution and analytical transmission electron microscopy. The microstracture consists of thin plates of ordered α2-Ti3Al (D019: ordered version of hcp) and γ-TiAl (Ll0: ordered version of fcc) phases, and interfaces of lamellae are atomically flat in a wide range. From detailed analyses of the microstructure and composition in nm scale, the α→γ phase transformation, which occurs during quenching and produces the extremely fine α2-γ lamellae, has been discussed.
Hardness of thin Films of Nanocrystalline Silver and Nickel Composites Studied by Nanoindentation and Finite Element Analysis
Authors: Qiu Boqin , Cheng Yang-Tse , Blanchard James P. 
Published: April 2011

AbstractWhile gas condensation and mechanical alloying have been used to produce nano-phase powders, an effective method of applying these powders as coatings is still lacking. Furthermore, fundamental studies of the mechanical properties of nano-phase powders may be complicated by the porosity associated with consolidation processes. Recently, we have made nano-crystalline composite thin films of Ag-Mo and Ag-Ni by depositing two immiscible elements simultaneous onto substrates. We found, using XRD and TEM, that the average grain size varies from 10 to 100 nm by choosing an appropriate substrate temperature. Nanoindentation measurements showed the hardness of the composite is increased four times by reducing the grain-size of both phases from 100 to 10 nm. The load vs. displacement curves were simulated using a finite element method (ABAQUS). A relationship between the hardness of the two-phase composite and the yield strength of each phase is obtained.
Structural Modification in Amorphous Magnetic Alloys Under Thermotreatment
Authors: Poperenko Leonid V. , Vinnichenko Mykola V. , Vovchak Vasyl’ V. , Yurgelevych Iryna V. , Zaichenko Sergei G. 
Published: April 2011

AbstractThe experimental results of research of structural modifications in amorphous magnetic alloys (AMAs) under thermotreatment obtained by angular and spectroellipsometric methods are presented and discussed. The ductile-brittle transition was observed for the ribbons of some 3d-metal-based amorphous alloys. The relationship between the principal angle of incidence φ0 and annealing temperature Ta of alloys was obtained for the ribbons of AMAs. The observed behaviour of φ0 is connected with appearance of the novel amorphous phase’s clusters inside the surface’s layers of alloys.The influence of melt’s overheating on the atomic and electronic structure of AMAs was studied. It was found that the increase of melt’s overheating temperature leads to the decrease of absorption index within the whole spectral range (ħω=0.5–4.38 eV). The structural anisotropy of AMAs and its changes after annealings were determined by reflectometric and ellipsometric measurements.
Aerosol Synthesis of Metal and Metal Oxide, Nitride and Carbide Nanoparticles Using an Arc Evaporation Source
Authors: Mahoney W. , Kempe M.D. , Andres R.P. 
Published: April 2011

AbstractNanoparticle synthesis by condensation from the vapor is a versatile process which allows control of both particle size and composition. We have developed a novel aerosol source for producing nanoparticles of metals and metal oxides, nitrides and carbides with controlled mean size. Metal is vaporized by heating a liquid metal pool by means of an atmospheric pressure d.c. arc. The evaporated atoms are entrained in a steady stream of inert gas and are quickly transferred to a quench region where the hot stream from the arc plasma is mixed with a second stream of cold gas. The role of the quench gas is to suppress aggregation by both rapid cooling and dilution. Metal oxide, nitride, and carbide particles are formed by the addition of oxygen, nitrogen, and methane respectively to the inert gas flow in either the arc or the quench region. The size of the primary particles is controlled by varying the metal atom density and residence time in the arc plasma and in the quench region. Cluster aggregation is controlled by varying the cluster density in the flow downstream from the quench region.
Investigation of TiN/TiSi2Bilayer Thin Films on Si (100) Substrate
Authors: Shor Y. , Pelleg J. 
Published: April 2011

AbstractIn this work the conditions of forming a bi – layer structure of TiN/TiSi2thin film on Si (100) substrate is investigated. Two methods of producing this structure were used: a) Deposition of Ti on Si (100), followed by reactive sputtering to obtain TiN on top of this layer and b) codeposition of Ti and Si on Si (100) and then deposition of TiN by reactive sputtering. The reactive sputtering was carried out in a mixture of N2/Ar with 20% N2. This amount is believed to be optimal for obtaining good quality and stoichiometric TiN films. Annealing is essential to form TiSi2and it was performed either in the sputtering chamber immediately after the deposition or by rapid thermal annealing (RTA). The structure of the specimens was analyzed by X-ray diffraction using step scanning, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). TEM analysis was done on cross sectional specimens and also electron diffraction results were recorded. Resistivity measurements were performed by four – point probe method. The influence of TiN on the silicide formation was established. The results indicate that in the presence of TiN the phase TiSi2was obtained, but in its absence Ti5Si3is formed under the same conditions of deposition and annealing. The stress distribution was investigated by Hall – Williamson curves and it was found that TiN stabilizes the silicide film and no peeling was observed. The effectiveness of TiN as diffusion barrier against Al and Si penetration was tested at 500°C/lh. It was found, that under these conditions, the TIN/TiSi2structure is about the same, as before the heat treatment. No Al penetration is observed.
Study on the Phase Transition from Amorphous Phases to Crystalline TiSi2
Authors: Nam H. G. , Cho Nam-Ihn 
Published: April 2011

AbstractTitanium silicides were prepared by coevaporation of Ti and Si on Si substrates at intermediate substrate temperatures followed by high temperature annealing. Depending on the deposition conditions, transmission electron diffraction analyses revealed two different halo patterns from the as-deposited samples. Variations in the deposition conditions included substrate temperature, deposition rate, and film thickness. Radial distribution functions were calculated to estimate the short range ordering of the amorphous phases. The interatomic distances of all the titanium silicide compounds were also calculated in order to compare them with the atomic ordering of amorphous phases. Phase transition from these amorphous phases to the first crystalline silicide is discussed in terms of kinetic variations as well as the atomic ordering.
Transient Phase Formation During the Growth of Epitaxial CoSi2 by Annealing of Co/Ti Bi-Layers on (100) Si
Authors: Miller D. J. , Selinder T. I. , Gray K. E. 
Published: April 2011

AbstractPhase evolution during the annealing of Co/Ti bi-layers on (100) Si has been studied by x-ray diffraction and analytical electron microscopy. X-ray diffraction performed in situ during annealing revealed a reaction pathway involving the formation of a transient phase when epitaxial CoSi2 films were grown. Analytical electron microscopy was used to identify this phase as a spinel-related phase, isostructural with Co2TiO4. This phase grows as a result of the presence of the Ti interlayer and a small amount of oxygen from the annealing ambient. Annealing in vacuum or other purified inert gases yielded polycrystalline CoSi2 films which form via a different reaction pathway that does not involve a spinel phase. This spinel phase may serve both to reduce the native oxide from the underlying Si substrate and to control interdiffusion between Si and Co during the reaction, thereby promoting epitaxial growth.
Theoretical Considerations about Phase Growth and Phase Formation
Authors: D'Heurle F. M. 
Published: April 2011

AbstractThe first part of this paper constitutes a summary account of reactive phase formation as seen from a purely kinetic point of view. In the longer second part a more detailed analysis of phase formation based on microscopic, and calorimetric observations is presented. It is shown that these phenomena also tend to be dominated by kinetic factors. This explains why purely kinetic considerations (which should always prevail in any case at some point) usually provide a fairly accurate account of the growth of new chemical phases forming on a solid substrate, regardless of the physical state (solid, liquid or gas) of the second reactant.
Influence of Stoichiometric Variations and Rapid Thermal Processing of β-FESI2 thin Films on their Electrical and Microstructural Properties
Authors: Döscher M. , Selle B. , Pauli M. , Kothe F. , Szymanski J. , Müller J. , Lange H. 
Published: April 2011

AbstractAmorphous irondisilicide thin films were deposited on silicon substrates in a RF sputtering process, followed by rapid thermal crystallization by means of moving the thin film beneath a line-shaped electron beam to form β-FeSi2. Depending on the deposition process parameters, films of a different stoichiometry can be produced. The deviations from the 1:2 stoichiometry, which have been determined by Rutherford Backscattering (RBS), are related to changes in the microstructure (studied by microscopic methods like TEM and AFM), the infrared phonon spectra (measured by FTIR spectroscopy) and the electrical properties of the crystallized films. The microstructure of the iron disilicide thin films is improved when the composition significantly deviates from 2.0, probably due to silicon interstitials in the silicide thin film. Films of different stoichiometry result in p- or n-type thin films with carrier densities below 5×1018cm−3 and hall mobilities up to 180cm 2/Vs. First results show that not only β-FeSi2-siliconheterojunctions as reported before but also pn-β-FeSi2-homojunctions show rectifying behavior. Rapid thermal processing with the line electron beam leads to a further improvement of the film quality when the scan velocity is increased up to the order of several cm/s.
Anisotropic Optical Response in β-FeSi2 Single Crystals and Thin Films
Authors: Bocelli S. , Guizzetti G. , Marabelli F. , Parravicini G. B. , Patrini M. , Henrion W. , Lange H. , Tomm Y. 
Published: April 2011

AbstractEllipsometric and reflectance spectroscopy in the range 1.4-5.0 eV as well as reflectance measurements in the infrared (10–80 meV) were performed on small single crystals of β FeSi2. The results show a clear anisotropy in the optical response which has been compared with theoretical calculations and data obtained on thin epitaxial films. Such a comparison gives evidence of the dependence of the optical response on the crystalline orientation of the film with respect to the surface.
Evolution of the Optical Response from a Very Narrow Gap Semiconductor to a Metallic Material in (FexMn1−x)Si
Authors: Bocellip S. , Marabelli F. , Spolenak R. , Bauer E. 
Published: April 2011

AbstractA study of the electrical resisitivity of (Fex.Mn1−x)Si with 0 < x < 1 indicates a crossover from an almost semiconducting state in FeSi to a metallic one in MnSi. Optical measurements show that the electronic structure and the vibrational behaviour appears to be essentially uneffected by the Fe/Mn substitution. Instead, a change of the free carrier density occurs, yielding a temperature and stoichiometry dependent plasma frequency.
Voltage-Tunable PtSi/SiGe/Si Schottky Diode Infrared Detectors
Authors: Jimenez Jorge R. 
Published: April 2011

AbstractThe theory of recently-reported cut-off wavelength-tunable silicide/SiGe/Si detectors is presented. The SiGe layer provides voltage-tunable barrier heights by tailoring the shape of the Schottky barrier. The increased tunability provided by the SiGe layer is now understood as being due to two related effects: first, keeping the barrier peak position fixed with bias, and second, moving the barrier peak further away from the interface. The second effect decreases quantum efficiency, which depends on the peak-to-interface distance. However, maximizing the first effect allows us to obtain desired levels of tunability without potential decreases in quantum efficiency. For voltage-switched, dual-window imaging, a tunable range of 5-12 μm is required over moderate voltages (10-15 volts), for which calculated detector parameters are total SiGe thicknesses (uniform plus graded) of ∼ 60-100 Å and boron doping levels of ∼ 4-8 × 1016cm−3throughout the depletion layer width (∼ 4000 Å, in the SiGe and in the underlying Si).
Process Windows of Nickel and Platinum Silicides in Deep Sub-Micron Regime
Authors: Xu D.-X. , Das S. R. , McCaffrey J. P. , Peters C. J. , Erickson L. E. 
Published: April 2011

AbstractIt has been observed that the sheet resistance of a Ti-salicided polysilicon-gate electrode or source/drain region increases significantly as the dimension reaches the lower sub-micron range. The resistance of platinum and nickel silicide (PtSi and NiSi), however, does not increase with reduced linewidth. We have studied PtSi and NiSi films with deep sub-micron linewidths on single crystal or poly-Si substrates. In this study, the material properties such as sheet resistance, grain structure and surface morphology of these silicide films in confined geometries are reviewed and compared with TiSi2. Process windows for forming and maintaining these silicides are explored.
Materials Compatibility Between Si/Sio2 Substrates and Batio3 Thin Films
Authors: Caballero J. V. , Fuenzalida V. M. , Ávila R. , Eisele I. 
Published: April 2011

AbstractBaTiO3 thin films, 50–60 nm in thickness, were evaporated in Ultra High Vacuum as well as under 1 mPa O2 pressure onto Si/SiO2 (30 nm) wafers. The substrate temperature during the evaporations was approximately 70 °C. The films were flash annealed in oxygen at 500 °C. The interfacial reactions were studied by XPS and AES Ar ion assisted depth profiling, and by RBS. Interdiffusion took place even at 70 °C. The XPS/AES depth profiles suggested strong interdiffusion, with Ba being the dominant moving species. The SiO2/BaTiO3 interface smears out with significant Ba concentrations up to half of the SiO2 thickness. Ti diffusion is remarkably lower. Barium is detected up to the SiO2/Si interface.
Tem Study of Diamond Films Grown from Fullerene Precursors
Authors: Csencsitsi R. , Gruen D. M. , Krauss A. R. , Zuiker C. 
Published: April 2011

AbstractTransmission Electron Microscope (TEM) techniques are applied to study the microstructure of diamond films grown from fullerene precursors. Electron diffraction and electron energy loss spectra (EELS) collected from the diamond films correspond to that of bulk diamond. Microdiffraction, high resolution images and EELS help determine that the first diamond grains that nucleate from fullerene precursors generally form on a thin amorphous carbon nterlayer and seldom directly on the silicon substrate. Grain size measurements reveal nanocrystalline diamond grains. Cross section TEM images show that the nanocrystalline diamond grains are equiaxed and not columnar nor dendritic. The microstructure of small equiaxed grains throughout the film thickness is believed responsible for the very smooth surfaces of diamond films grown from fullerene precursors.
Polycrystalline Silicon Films for Microelectromechanical Devices
Authors: Kahn H. , Stemmer S. , Mullen R. L. , Huff M. A. , Heuer A. H. 
Published: April 2011

AbstractPolycrystalline silicon is the most widely used structural material for surface micromachined microelectromechanical systems (MEMS). There are many advantages to using thick polysilicon films; however, due to process equipment limitations, these devices are typically fabricated from polysilicon films less than 3 μm thick. In this work, microelectromechanical test structures were designed and processed from thick (up to 10 μm) in situ boron-doped polysilicon films. The elastic modulus of these films was about 150 GPa, independent of film thickness. The thermal oxidation of the polysilicon induced a compressive stress into the top surface of the films, which was detected as a residual stress in the polysilicon after the device fabrication was complete.
Origin of In-Plane Texturing in Sputtered Mo Films
Authors: Malhotra A. K. , Yalisove S. M. , Bilello J. C. 
Published: April 2011

AbstractSputtered Mo films with a thickness of 2μm or greater have been previously shown by xray and TEM studies to grow with strong in-plane and out-of-plane textures under dynamic deposition conditions. In this work, the geometric conditions and mechanisms causing preferential grain alignment in the plane of growth for sputtered Mo films, with a nominal thickness of 2μm, were explored. Four different deposition configurations, obtained by varying the parameters such as the deposition angle and the rotation speed of the substrates, were used in order to modify the texture as studied by x-ray and SEM techniques. While a [110] type out-of-plane texture was observed for all four deposition configurations, a (110) type in-plane texture, and the corresponding grain alignment in the plane of growth, was observed only when the flux of adatoms was hitting the substrates at an oblique angle. The texture characteristics and the microstructure of the Mo films, as analyzed using the pole figure x-ray and SEM techniques, were observed to be very similar for films deposited on three different substrates, namely the Si(100) and Ni3Al(321) single crystals, and laboratory grade glass slides. The in-plane texture development under oblique deposition conditions was proposed to be due to a combination of two mechanisms, namely the preferential resputtering of some of the grains normal to and in the plane of growth caused by the higher energy adatoms in the flux, followed by termination of the preferentially sputtered grains due to geometric shadowing.
Growth and Texture of Polycrystalline Thin Films
Authors: Smith Richard W. , Ying Feng , Srolovitz David J. 
Published: April 2011

AbstractTwo dimensional non-equilibrium molecular dynamics simulations are performed to study microstructural evolution during the growth of polycrystalline thin films. Attention is focused on the interaction between grain boundaries and voids which form during deposition, and on the development of a preferred, crystallographic texture during film growth. In an intermediate temperature regime, where the film is cold enough to allow void formation but hot enough to allow grain boundary motion, boundaries move such as to attach themselves to voids as the voids form from depressions in the film surface. At lower temperatures, the boundaries have insufficient mobility to migrate toward the voids. At higher temperatures, films grow in the absence of voids. At low deposition kinetic energies, there is no tendency for polycrystalline films to develop a preferred texture. At moderate or high energy deposition kinetic energies, however, as in the case of magnetron sputtering, significant texture formation can result due to preferential (re)sputtering of atoms from the surface of grains with low-binding-energy exposed surfaces. Such preferential (re)sputtering provides a height advantage for grains possessing high-binding-energy exposed surfaces. The taller grains are seen to widen as deposition continues, resulting in the development of a preferred crystallographic orientation.