bluuebunny/crossref_metadata_2025_split huggingface dataset:
A First Principles Examination of Phase Stability in Fcc-Based Ni-V Substitutional Alloys
Authors: Mikalopas J. , Turchi P.E.A. , Sluiter M. , Sterne P.A. 
Published: March 2011

AbstractThe phase stability of fcc-based Ni-V substitutional alloys is investigated using linear muffin-tin orbitals total energy (LMTO) calculations. The method of Connolly and Williams (CWM) is used to extract many body interactions from the ground state energies of selected ordered configurations. These interactions are used in conjunction with the cluster variation method (CVM) to calculate the alloy phase diagram. The dependence of the interactions on the choice of configurations used to calculate them is examined.
Room Temperature Oxidation of Silicon Catalyzed by Cu3Si
Authors: Harper J.M.E. , Charai A. , Stolt L. , d'Heurle F.M. , Fryer P.M. 
Published: March 2011

AbstractWe demonstrate remarkably rapid oxidation of (100) silicon at room temperature catalyzed by the presence of Cu3Si. Thermal oxidation of Si is normally carried out at temperatures above 700°C. Oxidation of many metal silicides occurs more rapidly than that of Si, but under controlled conditions results in a surface layer of SiO2. In contrast, the oxidation process described here produces a thick layer of SiO2 underneath
the copper-rich surface layer. The SiO2 layer grows spontaneously to over one micrometer in thickness in several weeks in air at room temperature. Analysis by Rutherford backscattering, Auger electron spectroscopy, cross-sectional transmission electron microscopy and scanning electron microscopy reveals the presence of Cu3Si at the buried SiO2/Si interface, epitaxially related to the underlying Si substrate. Catalytic action by this silicide phase appears responsible for the unusual oxidation process.
Crystal Nucleation in Amorphous Si Thin Films During Ion Irradiation
Authors: Im James S. , Atwater Harry A. 
Published: March 2011

AbstractThe nucleation and transformation kinetics of the amorphous-to-crystal transition in Si films under 1.5 MeV Xe+ irradiation have been investigated by means of in situ transmission electron microscopy in the temperature range T = 480–580°C. After an incubation period during which negligible nucleation occurs, a constant nucleation rate was observed in steady state, suggesting homogeneous nucleation. A significant enhancement in nucleation rate during high energy ion irradiation (6 orders of magnitude) was observed as compared with thermal crystallization, with an apparent activation energy of Qn = 3.9 ± 0.75 eV. Independent analyses of the temperature dependence of the incubation time, the crystal growth rate, and nucleation rate suggest that interface rearrangement kinetics and not the thermodynamic barrier to crystallization, are affected by ion irradiation.
Structure and Phase Transformations in Thermoelastic Ni(1−x)TiCux) Thin Films Prepared by D.C. Magnetron Sputtering.
Authors: Chang L. , Hu-Simpsono C. , Grummon D. S. , Pratt W. , loloee R. 
Published: March 2011

AbstractThe intermetallic compound NiTi and its copper containing variants, Ni(1−x)TiCu(x), are capableof stress induced displacive tansformations which give rise to superelasticity and shape-memory effects. Thin films of these alloys, which may find use as sensors, microactuators, or as protective surface microalloys, are of increasing interest. In this study, thin films in the Ni(1−x)TiCUx) system, ranging in thickness from 250 nm to 5 μm, were prepared with a triode-type D.C. magnetron sputtering apparatus using a ternary alloy target. Both homogeneous films and periodic multilayer structures (with interspersed Ti-rich layers) were fabricated. of particular interest were shifts in composition with respect to the target, and the structural and phase transformation characteristics of the sputtered films. These phenomena were examined using transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray microanalysis. Transformation temperatures and enthalpies were determined by differential scanning calorimetry and confirmed by 4-point D.C. resistivity measurements. The as-sputtered films were amorphousbut crystallized during annealing at 923K. Electron diffraction and XPS data suggested the presence of oxygen. Single layer film compositions were shifted to slightly lower Ti fractions which depressed the onset of the transformation sequence by ˜35K and degraded phase stability during annealing. It was possible, however, to produce periodic multilayer films which showed evidence of thermoelastic phase transformations during DSC, resistivity, and in-situ TEM experiments. These films were stable with respect to vacuum annealing at 923 K for 6 h.
A Phase Diagram Approach for Predicting Reactions in Al/TiW(-Nitride) Thin-Film Systems
Authors: Bhansali A.S. , Raaijmakers I.J.M.M. , Sinclair R. , Morgan A.E. , Burrow B.J. , Arst M. 
Published: March 2011

AbstractA quaternary phase diagram for Ti–W–N–Al has been calculated from existing thermodynamic data, and is used to predict the Al/TiW-nitride reaction. The predicted reaction products-TiAl3, WAl5, WAl12, and AlN—were observed by XRD and TEM in annealed Al/TiW(-nitride) thin films. The sheet resistance of Al/TiW films increased by an order of magnitude at 550°C, whereas the increase in the case of the Al/TiW-nitride films was not even two-fold. The formation of an interfacial AlN layer was observed in the Al/TiW-nitride metallization. This AlN layer limits the interaction between Al and TiW-nitride, thus providing good thermal stability.
Composition and Structure Characterization of WNx Films Produced by RF Reactive Sputtering
Authors: Lin Dongliang , Yan Bewda , Yu Weili 
Published: March 2011

AbstractWNx film is one of the most promising materials for self-aligned GaAs NASFET because of its low electrical resistivity and high Schottky Barrier Height at the WNx /GaAs contact.In this paper, the effect of the sputtering conditions and the annealing environment on the chemical composition and structure of the WNx films deposited on Si and GaAs by RF reactive sputtering are studied.The results show that with the increase of the partial pressure ratio of nitrogen gas or decrease of the working pressure, deposition rate of WNx film decreases, whereas the atomic percentage of N in the deposited film increases before approaching saturation. The WNx films formed at high working pressure (≈5 × 10−2 torr) consist of W, WN or W2N phases depending on the nitrogen partial pressure ratio. Whereas the films formed at low working pressure (≈ 3 × 10−3 torr) are usually amorphous. Annealing in a flowing N2 gas causes the crystallization of the amorphous films, which mainly consist of W+W2N. There is no change for the crystalline films. However, annealing in H2 gas causes severe loss of nitrogen of the film, the film becoming single W phase eventually.
Laser Deposition of Molybdenum Oxide Thin Films From Organometallic Precursors
Authors: Olson Kurt A. , Schrader Glenn L. 
Published: March 2011

AbstractThin films of crystalline molybdenum oxides were formed on silicon surfaces by laser deposition. An ArF excimer laser was used to photodissociate molybdenum hexacarbonyl in an oxygen-containing ambient. Normal incidence of the laser led to the formation of very thin (< 1000 Å) films of crystalline MO4O11. The films were characterized by color, SEM, Raman spectroscopy, and X-ray diffraction.
Correlating CVD Process Parameters and Film Properties
Authors: Chow D. K. 
Published: March 2011

AbstractThis paper addresses an approach of predicting the effects of deposition process parameters on the film properties. The film resistivity is shown to correlate with other properties and testing conditions in explicit group form, and so is the rate of deposition with process parameters. Through a physical property relationship the two correlations merge to permit the prediction. Justifications for the correlations derive from both experimental and theoretical work already reported. Discussions on relative sensitivities of the variables toward another will follow.
The Epitaxial Growth of Copper on the (111) Surface of Silicon
Authors: Walker F. J. , Conner J. R. , Mckee R. A. 
Published: March 2011

AbstractThe progression of the epitaxy of Cu(111) on Si(111) has been studied using surface sensitive techniques and the as-grown film studied using high resolution transmission electron microscopy (HRTEM). A molecular beam epitaxy (MBE) system has been used to deposit films on 3-inch-diameter silicon substrates. Across this large area a graded thickness of 0 to 10 nm of copper was deposited and scanned using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). For films grown at 373 K, silicon alloys with the copper up to a thickness of 5.0 rim. LEED indicates an ordered R30°-√3×√3 Cu(111) surface which results from the alloying of copper and silicon. HRTEM images from the interface region show the alloy to be 2.3 nm thick, crystalline, and epitaxial to the Si(111) surface. There are indications that the interface alloy may be a metastable copper silicide. This alloy is important in the mechanism for the growth of Cu(111) on Si(111).
Atom Probe and Hrem Characterization of Transition Metal Multilayers.
Authors: Cerezo A. , Hetherington M.G. , Petford-Long A.J.K. 
Published: March 2011

AbstractThe direct measurement of the composition variations in transition metal multilayers has been carried out using the atom-probe and the position sensitive atom-probe (POSAP). The atom-probe and POSAP do not have sufficient resolution to determine the crystal structure and this complementary information has been obtained using high resolution electron microscopy.
Kinetics and Thermodynamics of Amorphous Silicide Formation in Metal/Amorphous-Silicon Multilayer Thin Films
Authors: Thompson C. V. , Clevenger L. A. , DeAvillez R. , Ma E. , Miura H. 
Published: March 2011

AbstractFormation of intermetallic phases upon heating of films composed of alternating layers of metal and amorphous silicon has been studied using power-compensated differential scanning calorimetry, crosssectional transmission electron microscopy, and thin film x-ray diffractrometry. Results for Ni/amorphous-Si (Ni/a-Si), Ti/a-Si, V/a- Si, and Co/a-Si are reviewed. In the first three cases, an amorphous silicide is the first phase to form. Further heating leads to thickening of the amorphous silicide and eventually to formation and growth of layers of crystalline silicides. In the case of Co/a-Si multilayer films, a crystalline silicide (CoSi) appears to be the first phase to form. In these systems calorimetric measurements suggest that there are barriers to nucleation of the crystalline phases, even though the energy reduction that would accompany their formation from pure components is large. It is suggested that interdiffusion may precede the formation of new phases at the original metal/a-Si interfaces, resulting in a significant decrease in the driving force for nucleation of the crystalline phases.
Structure and Thermodynamics of Amorphous Ti-Si Produced by Solid-State Interdiffusion
Authors: Holloway Karen , Moine Pierre , Delage Jacques , Bormann Rüdiger , Capuano Linda , Sinclair Robert 
Published: March 2011

AbstractThe thermodynamic and structural aspects of amorphous titanium silicide formation by solid-state reaction have been addressed. The radial distribution function of an amorphous Ti60Si40 reaction product has been determined by electron diffraction. It is an amorphous metallic alloy, with a coordination number of about 11.4, and a local arrangement of atoms which is similar to that in a crystalline silicide, Ti5Si4. The free energy of the amorphous alloy as a function of composition has been determined from the heats of crystallization of co-deposited amorphous Ti-Si alloys, and the heat of formation of the amorphization product as measured by differential scanning calorimetry (DSC). The latter was measured to be 35 ± 5 kJ/mole. Using these data, free energy of the amorphous Ti-Si phase has been calculated by applying the CALPHAD method. These results are discussed in light of the mechanism and energetics of the amorphization reaction.
Kinetic and Thermodynamic Aspects of Phase Evolution in Ti/a-Si Multilayer Films
Authors: Ma E. , Clevenger L.A. , Thompson C.V. , Tu K.N. 
Published: March 2011

AbstractThe growth of an amorphous Ti-Si phase and subsequent formation of crystalline silicides during solid-state reactions in Ti/a-Si multilayer films have been studied using power-compensated differential scanning calorimetry, cross-sectional transmission electron microscopy, and thin-film x-ray diffraction. By analyzing calorimetric data we have determined the activation energies for the formation of the various silicides (amorphous Ti-silicide, TiSi, C49-TiSi2, Ti5Si3) as well as their heats of formation. An amorphous silicide is the first phase to form during heating and we have measured the composition profile of this amorphous layer using scanning transimission electron microscopy. Metastable phase equilibria in the Ti-Si system are discussed in light of the thermodynamic and compositional information obtained in our experiments.
Formation and Growth of Amorphous Phases by Solid-State Reactions Between Co Thin-Films and III-V Compound Semiconductors
Authors: Shiau F.Y. , Chang Y.A. 
Published: March 2011

AbstractSolid-state amorphizaiton reactions (SSAR's) between Co thin-films and GaAs and InP have been investigated by transmission electron microscopy and Auger electron spectroscopy. Upon annealing at 260–300 °C, an amorphous phase was observed in the Co/GaAs system. Annealing at higher temperatures or for longer times led to the crystallization of this phase into a supersaturated CoAs structure. In the Co/InP system, annealing at 200°C for 1 hour led to the simultaneous formation of Co2P and an amorphous Co-In phase. At higher temperatures the amorphous phase crystallized into CoIn2 structure. For both systems, the amorphization reactions are attributed to the rapid diffusion of Co into the III-V substrates. The factors governing SSAR in ternary systems were discussed, with emphasis on the role of kinetics as opposed. to thermodynamic considerations.
Chemical Reactivity of Metal Particles Produced by Laser Ablation into Liquids
Authors: Parker W. L. , Boudjouk Philip 
Published: March 2011

ABSTRACTSpectroscopic evidence of the chemical differences between metal particles produced by laser ablation of metals into reactive fluid solvents and metal particles produced by less energetic means is presented. Specifically. 1) ablation of copper into fluid methanol produces metal particles in which some fraction of the metal is present In the cuprous oxidation state and 2) ablation of nickel into tetrahydrofuran results In metal particles less reactive to the solvent than those produced by ultrasound promoted chemical reduction.
Computer Simulation of Pulsed Laser Ablation for YBaCuO Superconducting Films
Authors: Nakamiya Toshiyuki , Ebihara Kenji , John P. K. , Tong B. Y. 
Published: March 2011

ABSTRACTThe dynamics of melting and ablation of high Tc YBa2Cu3O7-x superconducting thin films flashed by a pulsed KrF excimer laser(λ=248nm) or a pulsed Nd-YAG laser (λ =1.06μ m) were studied numerically. The fundamental model during a pulsed laser irradiation was a one-dimensional heat conduction equation. The finite element method was applied to solve the equation including the temperature dependence of the thermal conductivity of YBaCuO thin films. In addition, the microstructure of YBa2Cu3O7-x bulk(l.5mm thick) flashed by a pulsed XeCl excimer laser (λ =308nm) was investigated by scanning electron microscopy (SEM) in order to estimate the threshold incident laser energy density for surface melting and ablation. The good agreements between the numerical calculations and the experimental results were obtained.
Pulsed Laser Deposition of High Tc Superconducting thin Films: Present and Future
Authors: Wu X. D. , Venkatesan T. , Inam A. , Xi X. X. , Li Q. , McLean W. L. , Chang C. C. , Hwang D. M. , Ramesh R. , Nazar L. , Wilkens B. , Schwarz S. A. , Ravi R. T. , Martinez J. A. , England P. , Tarascon J. M. , Muenchausen R. E. , Foltyn S. , Estler R. C. , Dye R. C. , Garcia A. R. , Nogar N. S. 
Published: March 2011

ABSTRACTPulsed laser deposition (PLD) has been widely used for deposition of high Tc superconducting thin films, and is recognized as one of the best physical vapor techniques for the preparation of these films. The most important advantage of this technique is stoichiometric deposition; films can be made with the same composition as the target. Utilizing PLD, not only thin films but also multilayers and superlattices of high Tc superconductors have been fabricated. In this paper, the performance of the technique will be reviewed, and speculations regarding the future would be made.
Heteroepitaxial Metal Oxides on Silicon by Laser Ablation
Authors: Fenner D. B. , Fork D. K. , Connell G. A. N. , Boyce J. B. , Ponce F. A. , Tramontana J. C. , Viano A. M. , Geballe T. H. 
Published: March 2011

ABSTRACTThin epitaxial films of cubic - fluorite structured PrO2 and YSZ (yttria- stabilized zirconia) were grown on single crystal silicon substrates using the laser ablation - deposition technique. X-ray diffraction theta two - theta, omega rocking and phi scans indicate a high degree of epitaxial orientation of the films to the Si lattice. The highest quality of epitaxy was obtained with the PrO2 [111] oriented normal to Si(111) surfaces and the cubic YSZ [100] normal to Si(100) surfaces. For both PrO2 and YSZ, high epitaxial quality required the removal of the Si native oxide prior to deposition and careful control of the deposition environment. It was further found that the YSZ films on Si(100) were an excellent surface for subsequent laser ablation of YBCO films by the usual in situ process. The resistivity of this YBCO was ≈ 250 micro-ohm-cm at 300 K, extrapolated to the resistivity -temperature origin, showed a sharp transition to zero resistance at ≈ 85 K and was nearly identical to high quality YBCO films deposited on (bulk) YSZ substrates.
Spectroscopic and Ion Probe Characterization of the Transport Process Following Laser Ablation of Yba2Cu3Ox
Authors: Geohegan David B. , Mashburn Douglas N. 
Published: March 2011

ABSTRACTSpatial and temporal measurements of the optical absorption, optical emission and ion probe response in the ablation plume formed following pulsed 248 nm irradiation of Y1Ba2Cu3Ox are reported over laser energy densities from near threshold into the film growth regime. Time of flight absorbance-velocity profiles in vacuum indicate the formation and acceleration of a plasma front, with ions leading neutrals on the edge of the expanding plume. Ion probe screening measurements show that the laser plume is a well-shielded plasma with Debye lengths <10 μm at film deposition distances. Velocity distributions and estimates of ground state Ba+, Ba, Y+, and Y densities indicate that the populations of the ions outnumber those of the neutrals at high energy densities in vacuum. Measurements of the slowing of the plasma front and attenuation of the total charge reaching the substrate are reported for laser ablation in background pressures of oxygen. Absorption by ground state YO and BaO in the region close to the pellet indicates oxide densities ˜5 × 1013 cm−3 close to the pellet.
Influence of Laser Irradiation and Ambient Gas in Preparation of PZT Films by Laser Ablation
Authors: Morimoto Akiharu , Otsubo Shigeru , Shimizu Tatsuo , Minamikawa Toshiharu , Yonezawa Yasuto , Kidoh Hideo , Ogawa Toshio 
Published: March 2011

ABSTRACTPb(Zr0.52Ti0. 48)O3 (PZT) films were prepared on r-plane sapphire substrates by the laser ablation method utilizing ArF excimer laser in O2 or N2O environment. The composition of the films deposited in O2 environment was found to be fairly close to the composition of the target material for a wide range of substrate temperatures, 400 – 750 °c. Increasing the laser fluence (the laser power density) for the ablation enhances the formation of the perovskite structure rather than the pyrochlore one. Use of N2O ambient gas instead of O2 gas enhances the formation of the perovskite structure of PZT films. Furthermore, it was found that a laser irradiation on the growing film surface during deposition enhances the formation of the perovskite structure.
Picosecond UV Excimer Laser Ablation of LiNbO3
Authors: Beuermann Th. , Brinkmann H. J. , Damm T. , Stuke M. 
Published: March 2011

ABSTRACTUltrashort UV excimer laser ablation of materials shows several advantages over conventional UV excimer laser ablation. We describe new experimental results on lithium niobate, LiNbO3, using 308 nm pulses of 1 ps duration. The fluence threshold for material removal is reduced by one order of magnitude when compared with 16 ns pulses at 308 nm. In addition the etch rate is up to three times higher for picosecond pulses and it is independent of the diameter of the ablation area. We discuss a simple model describing the etching and ablation behaviour of materials upon interaction with UV excimer laser pulses of different pulse duration.
Congruent Evaporation and Epitaxy in Thin Film Laser Ablation Deposition (Lad) of Rare Earth Transition Metal Elements and Compounds
Authors: Gavigan J. P. , Givord D. , Lienard A. , Mcgrath O. F. K. , Rebouillat J. P. , Souche Y. 
Published: March 2011

ABSTRACTLaser ablation deposition (LAD) is a versatile thin film preparation technique which has been slowly developing for a number of years, and is currently receiving a lot of attention as demand increasingly exploits its advantages over other established techniques. Apart from its simplicity, one of its main advantages is the possibility of congruently evaporating any solid compound target, be it metal or insulator, due to the extremely high energy and instantaneous power densities attainable with pulsed lasers (up to 50 Jcm−2 and 1012 Wcm−2 for picosecond pulses). In this paper, we report on tests for both congruent evaporation in LAD of a number of rare earth - transition metal intermetallic compounds including Nd2 Fe1 3 B, Yzn0.7, Yni3, Y2 Fe15 and Yni5 for different preparation conditions (using a Nd:YAG laser λ = 1064, 532, 355 nm, τ = 35 ps and 20 ns) and on the epitaxial growth of Yni5 and W on monocrystalline sapphire substrates. Optical and electron microscopy were used to examine film morphology while congruent evaporation was confirmed using x-ray microprobe analysis. In-situ RHEED revealed good epitaxy of the films deposited on sapphire, with the hexagonal diffraction patterns obtained for YNis being identical to those of an YNi 5 reference single crystal.
Nanometer-Scale Pulsed Laser Modification of the Basal Plane of Graphite Observed with Stm
Authors: Schildbach M. A. , Tench R. J. , Balooch M. , Siekhaus W. J. 
Published: March 2011

ABSTRACTScanning tunneling microscopy has been used to document changes in the nanometer-scale morphology of the basal plane of highly oriented pyrolytic graphite after exposure to 7 ns, 1064 nm laser.pulses in air. Surface modification was visible at fluences far below those that produce melting. Damage appears first on step edges and consists of exfoliation of graphite layers and recession of steps through removal of mono- or multilayer patches.
Probing the Densities of Gap States in Intrinsic a-Si:H Using Space Charge Limited Currents of Electrons and Holes
Authors: Dawson Robin M. , Smith J. H. , Wronski C. R. 
Published: March 2011

ABSTRACTSpace charge limited currents of holes in intrinsic hydrogenated amorphous silicon (a-Si:H) have been obtained using novel p+-intrinsic-p+ (p-i-p) structures. The presence of these hole space charge limited currents is verified from their temperature dependence and their dependence on a wide range of intrinsic layer thickness. The carrier transport and space charge limited currents in the p-i-p structures are compared with those of n-i-n structures and the results are discussed in terms of a self consistent density of states in the gap.