bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of the Mechanical Alloying Process in Binary Systems
Authors: Herr U. , Klassen T. , Averback R.S. 
Published: April 2011

AbstractThe process of mechanical alloying in binary metallic systems is discussed in a microscopic picture. Special emphasis is put on systems with large positive heat of mixing. In these systems, a competition between thermal diffusion and forced transport takes place. Based on results from Monte Carlo studies of the effect of combined shear and diffusion processes on an atomistic scale, a simple rate equation approach is developed. The approach can reproduce the phase evolution in the simulation and the main features of the temperature dependence of the alloy phase fraction in steady state. The results are further compared with experimental data.
Anomalous Lattice Parameters in Iron-Copper Multilayers
Authors: Lloyd S. J. , Somekh R. E. , Stobbs W. M. 
Published: April 2011

AbstractX-ray, magnetism and electron loss spectroscopy data were obtained for a series of coherent Fe-Cu face-centred multilayers which suggest that there is a lattice parameter anomaly in the structure. The use of high resolution electron microscopy (HREM) and dark field imaging to measure spacing changes along the layer normal are compared. Experimental dark field images suggest that the Fe has expanded lattice spacings in the growth direction in contradiction to the predictions of a conventional elastic model for a coherent multilayer structure.
Initial Stage of Titanium Slicide Formation on Si(Lll) Substrate
Authors: Shingubara S. , Takata S. , Takahashi E. , Konagata S. , Sakaue H. , Takahagi T. 
Published: April 2011

AbstractDetailed analysis of Ti and/or TiSi2 islands growth have been made by UHV-STM observations after Ti deposition and subsequent annealing. It is shown that islands growth mode changes drastically at about 500 U for both cases on Si(111)-7×7 and on H-terminated Si(lll)-l×l. In the temperature regime higher than 500 °C, activation energies of islands growth are 1.12eV and 0.56eV for Si(M11)-7×7 and H-terminated Si(111) respectively. It is speculated that residual H-atoms combined with Si dangling bonds lowered surface diffusion activation energy.
Process Modeling and Integration of The Salicide Process Module for Sub-Half Micron Technology.
Authors: Apte Pushkar P. , Prinslow Douglas A. , Kittl Jorge A. , list R. Scott , Pollack Gordon 
Published: April 2011

AbstractMetal silicides have been used extensively in CMOS technology for reducing electrical resistance. As wafer-scale features have shrunk to the sub-half micron domain, obtaining a self-aligned silicide - or salicide - process that satisfies all requirements has become a significant challenge. One part of this challenge lies in developing the necessary scientific insights and technological innovations for the actual salicide process, while the other part lies in building a complete salicide process module which meets requirements of performance, reliability, ease of integration, control, etc. at the least possible cost and cycle-time for technology development. This second part is seldom addressed by researchers, and yet, is fundamentally important for successful application of any salicide technology to actual integrated circuit products. This paper presents a complete picture of the salicide module in the context of all the aforesaid components; and describes the use of abstraction and hierarchical models to capture process information and to facilitate process design. Prototype compact models for key wafer-state and performance outputs such as TiSi2 thickness and resistance are presented to demonstrate implementation of this process module.
Phase Transformations in Layered Fe-Si Structures
Authors: Fanciulli M. , Rosenblad C. , Weyer G. , Von Känel H. , Onda N. , Nevolin V. , Zenkevich A. 
Published: April 2011

AbstractThe kinetics of the phase transformations of the Fe-Si system and the Si/Fe and Fe/Si interfaces have been investigated by 57Fe conversion electron Mössbauer spectroscopy (CEMS). Single crystalline Fe films grown on Si(111) by molecular beam epitaxy (MBE) and polycrystalline Fe films grown by pulsed laser ablation deposition (PLD) have been thermally treated in vacuum and the formation of the different silicide phases has been monitored as function of temperature and time by CEMS.
Phase Development in Pt/ Si-Ge Alloy Layers
Authors: Carmondy Michael W. , Johnson Andrew S. , Kvam Eric P. 
Published: April 2011

AbstractThe phase development sequences for Pt layers on Si, Ge, and Si-Ge at 327°C were studied by X-ray diffraction, energy dispersive spectroscopy, and transmission electron microscopy. The reactions on pure Si and pure Ge followed the sequences reported previously. The reactions on the alloy layers differed slightly from the simple binary reactions. A ternary Pt(Si,Ge) reacted layer was formed on the alloy samples as the final phase on the Si-Ge alloy layer. This is discussed in terms of enthalpies of formation and the relative diffusion rates of Pt, Si, and Ge.
The Growth Of Thin Ti Films on Si(111)-(7×7) Surfaces
Authors: Saleh Adli A. , Peterson D. 
Published: April 2011

AbstractA study of the room-temperature growth of ultrathin Ti films (up to 7 ML) on clean and atomically flat Si(111)- (7×7) surfaces using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) is presented. The variations in the Auger signal due to Si L2.3VV with binding energy of 92 eV are used to model the growth morphology of this system. These measurements indicate the growth of an initial disordered and continuous Ti film of up to 1.6 ML in thickness, where the LEED pattern completely disappears and the Si Auger signal is strongly attenuated. As more Ti is deposited, this is followed by the disintegration of the continuous film and the formation of an intermixed Ti/Si film. This is evidenced by a change in the slope of the Auger signal time (AST) plot, and the reappearance of the LEED pattern. The modification in the overlayer composition for films thicker than 1.6 ML is confirmed by a change in the Si L2.3VV Auger peak that resembles the peak shape due to TiSi2.
Rapid Self-Ion Stimulated Process for TiSi2 thin Film Formation
Authors: Chapljuk V. I. , Gusev I. V. , Belevsky V. P. 
Published: April 2011

AbstractA method, technological arrangement, and some special features of the process for TiSi2 thin film formation is described in details. Rapid formation of low-resistivity single-phase TiSi2 layers is realized directly during deposition of Ti onto Si from DC plasma of metal vapour with simultaneous powerful self-ion bombardment at Wi > 2.5–3.1 W/cm2. Accelerated reactive diffusion is activated by thermal (dT/dτ ≥ 10°C/sec) and radiation (Eadd ≤ 2500 eV/atom) effects of powerful Ti+-ion bombardment. Thin TiSi2 layers with resistivity ρ = 13–20 μΩcm are formed on different Si substrates under optimum energetic conditions after 50 sec of the deposition. The film structure formation passes through three kinetic stages.
Low Temperature Transport Properties of Ru2Si3 Single Crystals
Authors: Gottlieb U. , Madar R. , Laborde O. 
Published: April 2011

AbstractWe present here low temperature transport properties of Ru2Si3 single crystals. Below room temperature the resistivity behaviour of this material is extrinsic. The Hall coefficient is positive down to about 10 K and the becomes negative below. We explain this crossover with a two band model. At very low T, the magnetoresistance of our crystals shows the typical behaviour for a doped semiconductor on the metallic side of the metal-insulator transition and can be described by a scaling law characteristic for weak localisation with strong electronelectron interactions.
The Use of Disordered Interlayers to Enhance Nucleation of Silicon Nitride During Chemical Vapor Deposition
Authors: Boekenhauer Rachel E. , Lauten Frederick S. , Sheldon Brian W. 
Published: April 2011

AbstractThin, disordered interlayers were used to enhance the nucleation of Si3N4. Continuous crystalline films were formed at relatively low temperatures (<1250°C) by using an amorphous, Sirich interlayer. The interlayer was produced by varying the CVD conditions (i.e., by using multistep processing). Samples were characterized with XPS, SEM, and TEM with concurrent EELS. The results indicate that the nucleation of crystalline material is very sensitive to the structure and composition of the disordered interlayers. Also, the structure and composition of the interlayers evolve during growth, such that crystalline material only nucleates when the interlayer provides favorable conditions.
Ar+ Implantation Effects on Polycrystalline Thin Films
Authors: Lee J. H. , Hwang C. W. , Shin J. E. , Jin Y. S. , Mah S. B. 
Published: April 2011

AbstractThe solid phase crystallization behavior of argon ion (Ar+) implanted very thin polycrystalline silicon (poly-Si) films has been investigated. Poly-Si films of 500Å thickness were deposited at 625°C by low pressure chemical vapor deposition (LPCVD). The films were amorphized by Ar+ implantation with 7 ° tilt angle. The amount of ions implanted was varied from 2.0 × 1013 cm-2 to 1.2 × 1015 cm-2 and the acceleration voltages from 40KeV to 120KeV. The films were recrystallized by furnace annealing at 580°C for 48 hours in N2 atmosphere, followed by 1000°C annealing The crystallinity of the recrystallized Si films and the distribution of the argon atoms in the film were investigated. It was found that the crystallinity strongly depended on the Ar+ implantation dose. The average grain size of Ar+ implanted film was about 0.25μm, which was smaller than that of Si+ implanted film of the same dose, 0.45μm. Ar atoms retarded the grain growth rate during the annealing process and the excess Ar atoms in Si films were segregated at the surface of silicon films after 1000°C annealing Poly-Si thin film transistors (TFTs) were fabricated at high temperature using Ar+ implantation technique. Remarkable electrical characteristics (Ids- Vgs) were obtained such as an electron mobility of 35 cm2/V.s, which was attributed to the enhancement of crystallinity by Ar+ implantation. But, segregated Ar atoms near the interface would give rise to structural deformation and crystalline defects which can act as the scattering and’ trapping centers for carriers.
Effects of Deposition Parameters on Crystallization of Pecvd Amorphous Silicon Films
Authors: Wang Yaozu , Kingi Reece , Awadelkarim Osama O. , Fonash Stephen J. 
Published: April 2011

AbstractPlasma-enhanced chemical vapor deposition was used to deposit a-Si:H thin films (∼ 1000 Å) at various temperatures below 300°C on Coming 7059 glass substrates using a silane-based plasma. These films were used as precursor materials to produce solid phase crystallized polycrystalline silicon (poly-Si) by conventional furnace annealing at 600°C in N2 ambient. The precursor a-Si and final poly-Si films were examined using spectroscopic ellipsometry and transmission electron microscopy. Precursor film deposition temperatures were found to affect the void density in the a-Si film and grain size in the resulting poly-Si film with lower deposition temperatures leading to higher void density in the a-Si film and larger grain size in the poly-Si film.
Electric and Optical Properties of μc-Si,Ge:H Alloys Deposited by Reactive Magnetron Sputtering (RMS)
Authors: Cho S. M. , Wolfe D. , Christensen K. , Lucovsky G. , Maher D. M. 
Published: April 2011

AbstractAmorphous and microcrystalline silicon-germanium alloys, a-SixGel-x:H and μc-SixGel-x:H, respectively, have been prepared by reactive magnetron sputtering (RMS) from pure crystalline Si and Ge targets in a hydrogen ambient using argon as the sputtering gas. We have investigated the structural, optical, and electronic properties of the as-deposited films. The optical and electrical properties, e.g., the ambipolar diffusion length, photoconductivity, and photosensitivity, were found to be comparable to those of device-grade a-SixGe1-x:H alloys, e.g., films with x ∼ 0.5, and band-gaps ∼ 1.3–1.4 eV. In contrast to the behavior of the a-SixGel-x:H alloys, the μc-SixGe1-x:H alloys do not display a Staebler-Wronski effect, as manifested by a decay of the photoconductivity under intense illumination.
Effectiveness and Reliability of Metal Diffusion Barriers for Copper Interconnects
Authors: Bai G. , Wittenbrock S. , Ochoa V. , Villasol R. , Chiang C. , Marieb T. , Gardner D. , Mu C. , Fraser D. , Bohr M. 
Published: April 2011

AbstractCu has two advantages over Al for sub-quarter micron interconnect application: (1) higher conductivity and (2) improved electromigration reliability. However, Cu diffuses quickly in SiO2and Si, and must be encapsulated. Polycrystalline films of Physical Vapor Deposition (PVD) Ta, W, Mo, TiN, and Metal-Organo Chemical Vapor Deposition (MOCVD) TiN and Ti-Si-N have been evaluated as Cu diffusion barriers using electrically biased-thermal-stressing tests. Barrier effectiveness of these thin films were correlated with their physical properties from Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Secondary Electron Microscopy (SEM), and Auger Electron Spectroscopy (AES) analysis. The barrier failure is dominated by “micro-defects” in the barrier film that serve as easy pathways for Cu diffusion. An ideal barrier system should be free of such micro-defects (e.g., amorphous Ti-Si-N and annealed Ta). The median-time-to-failure (MTTF) of a Ta barrier (30 nm) has been measured at different bias electrical fields and stressing temperatures, and the extrapolated MTTF of such a barrier is > 100 year at an operating condition of 200C and 0.1 MV/cm.
Crystallinity Effects in the Optical Modulation of Electrochromic Devices
Authors: Klein J. D. , Clauson S. L. 
Published: April 2011

AbstractThe electrochromic switching behavior of amorphous and crystalline WO3 thin films was investigated. The films were deposited on ITO-coated Corning 7059 glass substrates by sputtering. X-ray diffraction showed the crystalline film to have a mixed monoclinic/orthorhombic crystal structure. The coloration mechanisms in the visible and very near infrared were investigated by hydrogen insertion. A numerical fitting scheme allowed the coloration of the films to be expressed by means of the extinction index. As expected, crystalline WO3 exhibited more modulation in the very near infrared. A reversible crystallographic distortion was associated with the coloration of the crystalline WO3 films.
The Phase Diagram of Hydrogen in Ultra Thin Films
Authors: Jisrawi N. M. , Ruckman W. , Reisfeld G. , Wiesmann H. , Loeb F. , Gallego E. , Gorelik Y. , Thurston T. R. , Strongin Myron 
Published: April 2011

AbstractIn this paper, we discuss changes in the phase diagram of hydrogen in both bilayer (i.e. 200–2000 Å Nb/ 100 Å Pd on glass) and multilayer configurations. In fact, it is the changes in this phase diagram, in addition to the Pd coating, that makes theses bilayer systems useful for hydrogen gas sensors. Comparison of x-ray diffraction, electrical resistivity and volumetric measurements of the films before and after hydrogen charging indicate that the phase equilibria between a correlated (high concentration) and a dilute phase of hydrogen in Nb is not sensitive to the number of layers in the films. On the other hand, the experimental methods show different behavior for 200 Å thick Nb films and thicker (>400 Å) Nb layers. Diffraction results showing unisotropic lattice expansion will also be discussed..
Characteristics of a Reactively Sputtered Indium Tin Oxide Thin Film Strain Gage for Use at Elevated Temperatures
Authors: Gregory Otto J. , Dyer Stephen E. , Amons Paul S. , SLOT Arnout Bruins 
Published: April 2011

AbstractStrain sensors based on thin films of indium tin oxide (ITO) have been developed for a variety of applications, where the measurement of both static and dynamic strain are required at elevated temperatures. ITO thin films were prepared by rf reactive sputtering in Ar:02 mixtures from high density, electrically conductive targets having a nominal composition of 90% In203 and 10% Sn02. The resulting ITO films exhibited room temperature resistivities between 2x10−2 and 2x102 ω cm, an optical bandgap of 3.5 ev and tested “n” type by hot probe. These same films exhibited large negative gage factors (G=δρ/ ρδε) when tested at room temperature and a relatively low temperature coefficient of resistance when tested at elevated temperature in air. Specifically, gage factors approaching -100 with little hysteresis were observed for strains up to 700 μin/in and TCR's as low as 195 ppm/°C have been measured for the sputtered ITO films. In addition, these films were electrically stable and readily formed ohmic contacts with platinum at temperatures up to 1180°C. In this paper, we report on the electrical properties and piezoresistive properties of ITO based strain gages at temperatures up to 1180°C. Prospects of using ITO thin films as the active strain elements in high temperature strain gages and the characteristics of strain sensors based on ITO are discussed.
Initial Stage of Cvd Copper Deposition on Teos Oxide
Authors: Nguyen Tue , He Shusheng , Charnesky Lawrence J. 
Published: April 2011

AbstractSelective deposition of copper on metal (such as TiN) versus dielectric (such as oxide) requires understanding of the mechanism of chemical-vapor-deposition copper deposition. This work studies the initial stage of CVD copper deposition with hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (Cu-hfac-tmvs) precursor on tetraethylorthosilicate (TEOS) oxide using Fourier transform infrared spectroscopy (FTIR).
Magnetic Properties of Sputtered Fe-O and Co-O Thin Films
Authors: Dimitrov D. V. , Murthy A. S. , Hadjipanayis G. C. , SWANN C. P. 
Published: April 2011

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.
Simulation of Dislocations in Ordered Ni3Al by Atomic Stiffness Matrix Method
Authors: Hsu Y. E. , Chaki T. K. 
Published: April 2011

AbstractA simulation of structure and motion of edge dislocations in ordered Ni3Al was performed by atomic stiffness matrix method. In this method the equilibrium positions of the atoms were obtained by solving a set of linear equations formed by a stiffness matrix, whose terms consisted of derivatives of the interaction potential of EAM (embedded atom method) type. The superpartial dislocations, separated by an antiphase boundary (APB) on (111), dissociated into Shockley partials with complex stacking faults (CSF) on (111) plane. The core structure, represented by the Burgers vector density distribution and iso-strain contours, changed under applied stresses as well as upon addition of boron. The separation between the superpartials changed with the addition of B and antisite Ni. As one Shockley partial moved out to the surface. a Shockley partial in the interior moved a large distance to join the lone one near the surface, leaving behind a long CSF strip. The decrease in the width of the APB upon addition of B and antisite Ni has been explained by a reduction of the strength of directional bonding between Ni and Al as well as by the dragging of B atmosphere by the superpartials.
First Principles Simulations of Nanoindentation and Atomic Force Microscopy on Silicon Surfaces
Authors: Perez R. , Payne M. C. , Stich I. , Terakura K. 
Published: April 2011

AbstractTotal-Energy pseudopotential calculations are used to study both the onset and development of plasticity in nanoindentation experiments and the contrast mechanism in non-contact AFM images on Si (111) surfaces. As regards nanoindentation, plastic flow of atoms towards interstitial positions and extrusion of material towards the tip walls, stabilized by the adhesive interactions with the tip, are the dominant mechanisms. These plastic deformations are triggered by the delocalization of the charge induced by the stress in the elastically compressed structure. Atomic resolution contrast in AFM is shown to be clearly enhanced by the partial covalent chemical interaction between the dangling bonds of the adatoms in the surface and the apex atom in the tip. The contrast mechanism can be understood in terms of the coupling between the tip and the charge transfer modes among the different dangling bonds in the surface.
Configuration Dependence of the Vibrational Free Energy in Substitutional Alloys and Its Effects on Phase Stability
Authors: Garbulsky G. D. , Ceder G. 
Published: April 2011

AbstractThe lattice vibrations influence the ordering tendencies in substitutional alloys through the configurational dependence of the vibrational free energy. In this paper we study the size of this effect and the trends with chemical affinity and size mismatch. By analyzing available experimental information and by studying simple model systems for which the phonon frequencies can be easily computed, we find that a) changes in transition temperatures of order-disorder transformations of 30% due to the lattice vibrations may not be uncommon; b) the transition temperatures are usually lowered when the vibrations are included in the modeling of the system, except for certain combinations of size mismatch and chemical affinity; and c) that the largest contribution to the configurational dependence of the vibrational free energy is due to the intermediate and high frequencies of the spectrum.
Structural Phase Transition from Fluorite to Orthorhombic FeSi2 by Tight Binding Molecular Dynamics
Authors: Miglio Leo , Celino Massimo , Meregalli Valeria , Tavazza Francesca 
Published: April 2011

AbstractIn this paper we report a molecular dynamics simulation at constant pressure and constant temperature of the structural phase transition occurring in epitaxial FeSi2 from the fluorite phase (metallic and pseudomorphic) to orthorhombic one (semiconductor and bulk stable). The evolution of the electronic density of states is carefully monitored during the transformation and we can show that the Jahn-Teller coupling between the density of states at the Fermi level and the lattice deformation drives the metal-semiconductor transition.
Molecular Dynamics Simulations of SiSe2 Nanowires
Authors: Li Wei , Kalia Rajiv K. , Vashishta Priya 
Published: April 2011

AbstractStructural and mechanical behavior of SiSe2 nanowires is investigated with the moleculardynamics (MD) method. Nanowires contain finite number of non-intersecting chains of edgesharing Si(Sel/2)4 tetrahedra. The simulations are based on an effective interatomic potential containing both 2- and 3-body interactions. It is found that the nanowires remain highly crystalline and stay in the elastic deformation regime up to a critical strain. Under large uniaxial strain, fracture of the nanowires is initiated by broken bonds in one of the chains at the outermost layer. This induces cross-linking among the neighboring chains, which leads to the presence of cornersharing tetrahedra and local amorphization. Local amorphization propagates across nanowires while multiple cracks start at the boundaries of the amorphous region. The dynamics of amorphization and fracture are discussed.