bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsed Lasek Atom Probe Analysis of Stoichiometry Variations in GaAlAs
Authors: Grovenor C.R.M. , Cerezo A. , Smith G.D.W. 
Published: March 2011

ABSTRACTThe recent development of Pulsed Laser Atom Probe (PLAP) analysis has allowed routine analysis of the composition of a wide range of semiconducting materials. This paper presents results on the analysis of stoi chiometry variations in MOCVü GaAlAs layers demonstrating that accurate analysis of aluminium concentration fluctuations can be achieved with this technique.
Spa-Leed Measurements on Etched and Polished Silicon (111) Surfaces
Authors: Hahn Peter O. 
Published: March 2011

ABSTRACTThe atomic structure of etched and polished Si (111) surfaces has been determined quantitatively on an atomic scale by SPA-LEED (spot profile analysis of low energy electron diffraction) in an ultrahigh vacuum. The energy dependant broadening of the diffracted electron beam yields the average size of step free terraces and the distribution of the atomic steps.Whereas acid etched Si (111) wafers exhibit surfaces with very high step atom densities, alkaline etched Si (111) wafers show atomically very flat surfaces besides macroscopic steps. In chemo-mechanical polishing of these silicon wafers bright LEED patterns exhibiting the atomic structure at the actual surface were obtained. No damage or defects could be observed with LEED during this process. This indicates that the removal of Si is mainly controlled by chemical reaction. In an intermediate step the wafers exhibit a slight surface roughness (“haze”) observable by optical Nomarski contrast microscopy or by light scattering. This is correlated qualitatively to a broadening of LEED spots for a phase relation, indicating that the atomic steps are distributed over many atomic layers creating a superimposed long range roughness. After polishing this long range roughness (haze) disappears and atomically smooth surfaces were obtained. Haze free polished Si (111) wafers exhibit on average less than one atomic step for a row of 30 atoms which represents the instrumental resolution. Definitely misoriented wafers show regular terraces. The regularity is increasing with proceeding polishing. The number of atoms per terrace is correlated to the angle of misorientation, demonstrating the high quality of the polished wafer surface.
Growth of Large Crystalline Grain Al Thin Films on Amorphous Substrates
Authors: Sberveglieri G. , Canevari V. , Romeo N. , Spaggiari C. 
Published: March 2011

ABSTRACT(111) uniquely oriented large crystalline grain Al thin films have been grown on amorphous substrates such as glass or fused quartz. Al has been evaporated by means of an electron beam in a vacuum of 10-7 mbar which was obtained by a conventional oil diffusion pump in conjunction with a titanium sublimation pump and a series of shields cooled at the liquid nitrogen temperature. By studying the variation of the grain size as a function of the growth temperature, a large increase in the grain size has been found at a substrate temperature 100°C below the Al melting point. This has been interpreted as due to the beginning of the metal surface melting and, as a consequence, to the quasi rheotaxial growth of the metal on itself. When the growth has been carried out at a substrate temperature close to the Al melting point (625°C), the grain size has been found out to increase exponentially as a function of the film thickness with a slope which slows down at a thickness of about 1 pm. (111) oriented columnar grains with a size of 50 – 100 pm, hitherto unreported, have been obtained on glass substrates kept at a maximum temperature of 655 °C. The surface morphology of the Al films has been studied by SEM microscopy while the film structural properties have been studied by an X-ray powder-diffracto-meter and by computer - controlled pole figure goniometer.
Interconnects and Contacts for VLSI Applications
Authors: Sinha A. K. 
Published: March 2011

ABSTRACTThe power of VLSI circuits is, to a large measure, derived through an extensive network of fine-line metalization interconnects used to wire up various components on the chip. For example, the 1Mb DRAM utilizes three levels of conductors to interconnect over one million each of transistors and capacitors on a chip. The combination of larger chip dimensions and finer scaling generates several technology concerns that must be addressed by a variety of measures, including an optimum choice of metalization processes. These concerns are related to parasitics, defect density and generic reliability.This talk will review trends in materials/processes to control RC time constants, series resistances, fine-line metal defects during pattern transfer, control of topography-related defects and generic reliability related issues such as contact electromigration and ∝-particle sensitivities.
High Dose Implantation of Nickel into Silicon
Authors: Campisi G. J. , DIETRICH H. B. , Delfino M. , Sadana D. K. 
Published: March 2011

ABSTRACTSeveral silicon wafers were implanted with 58Ni+ at an energy of 170 keV and a current density of 12 μA cm-2 to doses between 5 × 1015 and 1.8 × 1018 ions cm-2. The substrates were phosphorus doped n-type <100> Czochralski grown silicon wafers. The wafers were water cooled during implantation and the surface temperatures was monitored with an infrared pyrometer and controlled to < 70°C. Samples were subsequently furnace annealed at 900°C for 30 min in nitrogen. The as-implanted and annealed samples were analyzed using cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering (RBS) spectroscopy, spreading resistance depth profiling (SRP), and scanning electron microscopy (SEM). Micro-crystallites of NiSi2 (2–5nm) buried within an amorphous matrix formed during the 1.5 × 1017 ions cm-2 dose implantation. For higher doses above 3 × 1017 Ni+ cm-2, ion beam sputtering occurred. After annealing, rapid diffusion of nickel and solid-phase recrystallization of the amorphous regions occurred.
An Experimental Technique to Obtain the Specific Contact Resistance of Multi-Layer Interconnections
Authors: Harrison H. B. , Reeves G. K. , Walton A. J. 
Published: March 2011

ABSTRACTThe specific contact resistance between any two interconnecting layers is of vital importance in determining the total interconnection resistance of these layers. We present here an experimental technique to obtain the specific contact resistance when both of the conducting layers have finite conductivities of similar magnitudes. This structure is then used to obtain practical information on the poly to single crystal interconnection system, details of which are present. Finally a modification to this system is proposed and its status reviewed.
Stability Of Thin Film Amorphous Metal Alloys
Authors: Saris F. W. , Hung L. S. , Nastasi M. , Mayer J. W. 
Published: March 2011

ABSTRACTThermal stability of self supporting amorphous films is reviewed in terms of a simple kinetic model. A semi-empirical relationship between the crystallization temperature and the heat of hole formation is applicable only for systems with negative heat of mixing.Interaction of amorphous diffusion barriers with Si substrates and Al overlayers is also reviewed for near noble-refractory alloys. If their crystallization temperature is higher than their reaction temperature, there is no correlation between the two parameters. The reaction takes place when the annealing temperature reaches a value at which compounds can be formed of both constituents of the alloy. Finally, comparison is made to reactions of crystalline alloys with Si.
Mechanical and Thermo-Mechanical Protection by Alumina Sol-Gel Coatings
Authors: Gruninger Mark F. , Wachtman John B. , Haber Richard A. 
Published: March 2011

ABSTRACTAlumina coatings made by the sol-gel process using aluminum sec butox-ide can be made with variable surface area and porosity by firing on dense alumina substrates in the firing range 700 to 1000 C. These coatings are found to have large (over 100 MPa) compressive stresses and to cause a small but significant strengthening of the substrates. Within this firing range the surface area decreases while both the internal stress and strengthening effect increase with increasing firing temperature. Wear rate values are high but decrease with increasing firing temperature.
Problems In Realistic Modelling Of Interfacial Reactions
Authors: Allen Charles W. , Sargent Gordon A 
Published: March 2011

ABSTRACTFor modelling the reaction of chemically distinct materials in which intermediate alloy phases are formed a simple thermodynamic description is not adequate. Despite thermodynamic prediction of multiple product phases, a single phase generally forms first which is not necessarily that of greatest thermodynamic stability or of simplest structure. Such initial reaction processes may be modelled as metastable perltectoid (solid-solid) or perltectlc (solid-liquid) reactions, characterized by large thermodynamic driving forces with superimposed kinetic and morphological constraints. The interfacial reaction problem is reviewed in light of heterogeneous nucleation theory with emphasis on non-classical aspects.
Multi-Step Micro-Crystallization Studies on Amorphous Fe90-x Six B10 Alloys
Authors: Minor W. , Malmhall R. , Roig Anna , Inoue A. , Rao K. V. 
Published: March 2011

ABSTRACTIn order to elucidate the sensitivity and information that can be obtained from Magneto-Thermo-Gravimetric, MTG, technique, we present a comparative study of our results on structure relaxation as well as crystallization sequences as a function of time and temperature of amorphous Fe90-xSixB10 alloys in the Fe-rich regime, with those obtained from synchrotron Energy-Dispersive- X-ray-Diffraction, EDXD, and Differential Scanning Calorimetry, DSC methods.
Analysis of Rapid Solidification Process in The Double-Roller Method
Authors: Kogiku F. , Yukumoto M. , Shibuya K. , Ozawa M. , Kan T. 
Published: March 2011

ABSTRACTHigh-silicon steel was rapidly solidified to thin strips by the double roller method. Two typical macrostructures were observed: one with an equiaxed zone and the other without. The formation of the equiaxed zone is caused by an excessive gap between the rollers. Heat transfer calculations and dendrite arm syacing measurements both suggested that the cooling rate is about 103 to 104 K/sec.
Study of The Origin of The Magnetic Anisotropy in RF Sequential Co-Sputitered Co100-XBX and Co74Fe6B20 Thin Films
Authors: Kim D. Y. , Walser R. M. 
Published: March 2011

ABSTRACTWe prepared thin, amorphous, compositionally modulated films (CMF) by RF sequential co-sputtering with Co, B, and Fe targets. In principle this technique can produce controlled, small (<15 Å) scale modulations in composition. The in-plane anisotropies and coercivities of the CMF were more than one magnitude larger than those of typical thin, homogeneous, amorphous, alloy films (AF). The increase in anisotropy was growth induced and could be reduced by annealing to values comparable to those of amorphous AF. The coercivity, however, could not be significantly decreased by annealing, except in CMvF with the highest boron concentration. The stability of the coercivity might, therefore, be an observable consequence of the small scale composition heterogeneity.
New Microstructural Model for Sputtered Co-Cr Magnetic Thin Films
Authors: Niimura Yoshiro , Naoe Masahiko 
Published: March 2011

ABSTRACTRapidly solidified Co-Cr thin films with a perpedicular magnetic anisotropy have been extensively investigated as one of the most promising media for perpendicular magnetic recording system. Most of these films used to be prepared by conventional RF diode sputtering and vacuum evaporation methods. We have developed the Facing Targets Sputtering apparatus which is able to deposite the magnetic thin films without the bombardment by high energy particles to the substrate along with the capabilities to deposit films under wide range of argon gas pressure at high deposition rate. It has been found that the texture and crystallographic structure of the sputtered films are primarily dependent on the argon gas pressure and the films prepared by the Facing Targets Sputtering exhibit quite different properties from the films prepared by conventional methods. The films deposited in the argon gas at the low pressure on the plasma-free substrate using the Facing Targets Sputtering are composed of the fine polyhedral grains packed densely from the initial growth layer to the surface layer of the film. They show exellent c-axis orientation of hcp crystallites, smoother surface textures and the superior perpendicular magnetic anisotropy as compared with the films composed of so-called columnar grains deposited in the argon gas at the higher pressures using the conventional RF diode sputtering. These results imply that the sputtering apparatus which is capable to deposit Co-Cr films in the argon gas at relatively low pressure is indispensable for the preparation of superior perpendicular magnetic recording media. Therefore, the Facing Targets Sputtering apparatus seems to be quite suitable for this purpose. Further, we have proposed a new micro structural model with fine polyhedral grains obtained by our sputtering method, because this model will have the ideal structural characteristics for ultra high density perpendicular magnetic recording.
Rapidly Solidified Metal Foils by Melt Overflow
Authors: Gaspar Thomas , Hackhan Lloyd E. , Sahai Yogeshwar , Clark W.A.T. , Wood John 
Published: March 2011

ABSTRACTA single roller technique called melt overflow for direct casting metallic sheet, strip or foil is described. A simiple heat transfer nodel is developed to predict foil thickness frorn process parameters. The model agrees with thickness of Ti-6Al-4V cast strip. Cooling rates as high as 105 K/s are estimated from measuremnents of secondary dendrite arm spacings in 7075 aluminum alloys. Applications include magnesium-graphite composites.
Formation of A Quasicrystalline Phase from The Glassy State in Pd-U-Si
Authors: Drehman A. J. , Poon S. J. , Lawless K. R. 
Published: March 2011

ABSTRACTMetallic glasses of composition Pd58.8U20.6Si20.6 can be transformed to a metastable single phase with quasicrystall ne order by thermal annealing. The icosahedral symmetry of this phase was verified by both electron and x-ray diffraction. Although the metallic glass can be formed over a broad compositional range the homogeneity range of this icosahedral phase is less than 1%. This indicates strong chemical ordering in the quasicrystalline state.
Metastable Extensions of Intermediate Phases in Some Aluminum - Rare-Earth Metal Systems
Authors: Quan M.X. , Haldar P. , Werth J. , Giessen B.C. 
Published: March 2011

ABSTRACTUsing the arc-furnace hammer-and-anvil method, metastable alloys in the Al-rich portions of four Al-RE systems (10-30 at. pct. RE; Re = Gd, Ho, Er and Y) were prepared and examined by XRD. The principal results are: all equilibrium alloy phases [Al4RE (T phase), Al3RE (CN12 close-packed phases) and Al2RE (Laves phase)] have substantial metastable solid solubilities for excess Al; e.g., in the Al-Y system, L phase is extended from 66.7 up to 86 at. pct. Al, suppressing any formation of the Al3RE phase in that system.For early RE elements up to and including Gd, T phase is favored; for alloy chemically intermediate RE elements such as Y, L phase is dominant and for late RE elements (after Ho), the CP phases are extended most. DSC work indicates the formation of additional metastable phases occurring during equilibration.
Properties of Aluminum Thin Films Prepared by Targets Facing Type of Sputtering System
Authors: Hirata T. , Kaku S. , Naoe M. 
Published: March 2011

ABSTRACTThe Targets Facing Type of Sputtering (TFTS) system can deposit very dense films on substrates at a high rate without undesirable influences of the plasma. Using this system, Al films 0.7 ∿ 1.5 µm thick were deposited in an argon gas pressure PAr of 9.7 × 10−2 Pa.The grains with irregular shape grew as PAr became high. However, the number of grains per unit area decreased and their size became small when the bias voltage to the substrate Vb was -40 V. Consequently, the film surfaces became smooth. The Al films became hardest at Vb of about -40 V and were twice as hard as ones prepared without the bias voltage.The step coverage of these Al films was very satisfactory to the wiring of the integrated circuit (IC) by adjusting Vb and PAr at the proper values.
Rapidly Solidified Titanium
Authors: Froes F. H. , Rowe R. G. 
Published: March 2011

ABSTRACTThe attributes and requirements for rapid solidification (RS) are discussed and related to the characteristics of the titanium system. The extreme reactivity of liquid titanium requires the development of RS production methods tailored to this system. Compaction and processing techniques are presented followed by a discussion of the various alloy classes which have been produced by the RS approach: conventional alloys such as Ti-6Al-4V, rare earths, metalloids, eutectoid formers, beta alloys, amorphous materials, high aluminum alloys, aluminides, and other minor classes. Finally some thoughts on the future of this technology are presented.
Formation of Metastable Phases in Rapidly Quenched Binary Ti Alloys
Authors: Whang S.H. , Chi C.S. 
Published: March 2011

ABSTRACTRapid quenching of binary Ti alloys from the melt results in various metastable phases. A systematic study has been conducted in order to elucidate principles associated with the formation of metastable phases in binary Ti alloys resulting from rapid quenching. These metastable phases that include α’, α” phases, metastable β phase, and w phase are discussed with regard to their occurrence and the extension of a phase as a function of cooling rate. Effect of cooling rate and mechanical stress applied during cooling on metastable phase formation was investigated.
Rare Earth Oxide Dispersoid Stability and Microstructural Effects in Rapidly Solidified Ti3Al and Ti3A1-Nb
Authors: Sutliff J. A. , Rowe R. G. 
Published: March 2011

ABSTRACTThe microstructures of titanium aluminide alloys containing a rare earth oxide dispersion have been characterized using analytical electron microscopy. The alloys, based on Ti3A1 (alpha-2), contained 0 to 10.7 atom% Nb and 0.5 atom% Er. Alloys were rapidly solidified by melt spinning and were subsequently consolidated by HIP and extrusion. The microstructure of each alloy was examined in the as-cast, as-HIP'ed, and as-extruded conditions. A fine dispersoid spaced less than 100 nm apart was observed in ribbon aged at 750°C. The effects of processing conditions on the dispersoid distribution as a function of matrix chemistry were studied. Hot deformation was also examined to investigate the nature of the interaction between the dispersoids and the matrix during deformation.
Mechanical Properties of Rapidly Solidified Nickel-Base Superalloys and Intermetallics
Authors: Taub A. I. , Jackson M. R. 
Published: March 2011

ABSTRACTThe improvements in the mechanical properties of nickel-base alloys that have been made possible by rapid solidification processing are reviewed. The results of processing by powder metallurgy, laser melting, low pressure plasma deposition and spray forming are examined. In general, the increased homogeneity obtained by rapid solidification allows for increased alloying and improved hot workability. The refined grain size improves the low and intermediate temperature strength, but leads to lower strengths at high temperature. For the high temperature applications, post solidification grain growth is required, as for example the directional recrystallization of powder metallurgy preforms. The development of a novel means of producing a fine dispersion from amorphous alloy precursors and the recent work attempting to improve the ductility of the intermetallic phases NiAl and Ni3A1 are also described.
The Strengthening Mechanism in Consolidated Rapidly Solidified Alloys
Authors: Otooni Monde A. 
Published: March 2011

ABSTRACTAttempts have been made to study mechanisms of strengthening in the Ni68W22C8B2 and the Ni45CO20 Cr10MO4Fe5B16 alloy systems during their amorphous crysialline transitions. In the Ni68W22C8B2 system where amorphous particulates of varying sizes have been cons Ti a ed at high pressure and low temperature (3.6 MPa, and 673°K respectively), the initial stage of crystallization is marked by transformation of the localized regions of the specimen. These crystallized regions contain microcracks and voids. Microhardness measurements from the consolidated specimens indicate an increasing trend in the microhardness with decreasing particulate sizes. Premature failures of the consolidated specimen during tensile stress measurements have been attributed to the presence of microcracks and voids in these specimens. In the Ni45Co20Crl0Mo4Fe5B16 alloy system isothermal annealing of an initially amorphous alloy has been allowed to produce grains of varying sizes. The tensile stress measurements from these thermally annealed ribbons indicate two distinctly different functional relationships between the strength, σ, and the grain size parameter, λ. In the early stage of transformation where grain reach a maximum growth of up to 400 Å, the functional form of the strength, σ, with the grain parameter, λ, is σ = σ + K Log λ, where σO and K are constants. During latter stages of transformation, where grains larger than 400 Å have been formed, the strength, σ, varies with the inverse square root of the grain sizes. This latter relationship is analogous with the well known Hall-Petch relationships, which describes the strength, σ, as a function of the grain sizes in conventionally processed alloys.
Microstructural Characterization of Rapidly Solidified Type 304 Stainless Steel
Authors: Wright R. N. , Flinn J. E. , Korth G. E. 
Published: March 2011

ABSTRACTThe microstructures of rapidly solidified Type 304 stainless steel powders produced by vacuum gas (VGA) and centrifugal atomization (CA) have been examined. The solidification morphology and phase distribution have been characterized using optical and scanning electron microscopy, and the relative amounts of ferrite and austenite have been quantified using x-ray diffraction. Most CA powder particles contain both fcc and bcc phases, with the bcc phase predominating at small particle sizes and the fcc phase at large particle sizes. The VGA powder generally contains less ferrite, with very little dependence on the particle size. The ferrite was metastable and transforms to austenite on annealing at 900°C.
Rapid Solidification of An Al2O3-25WT.PCT.ZrO2 Oxide Alloy
Authors: Ando Teiichi , Shiohara Yuh , Flemings M.C. 
Published: March 2011

ABSTRACTTEM observation of the morphology of alumina dendrites in a rapidly solidified Al203-25w/oZrO22 oxide alloy revealed three distinct dendrite morphologies corresponding to α-, γ- and δ- aluminas. STEM analysis showed the center of the α and γ dendrites to be solute poor, but the δ dendrite center to be solute rich, indicating possible solute trapping. Theoretical calculations show interface growth velocities in excess of 3m/sec.
Thermal Stability of Rapidly Quenched TI-NI-AL Amorphous Alloys
Authors: Aoki K. , Hiraga K. , Masumoto T. 
Published: March 2011

ABSTRACTTi-Ni-Al alloys were rapidly quenched from a molten state by the melt spinning method. Three kinds of metastable phases, namely, amorphous,nonequilibrium and quasicrystalline phases are formed in these alloys. The amorphous phase is formed in the range of 35 to 70 at% Ti and 0 to 25 at% Al. The nonequilibrium phases are formed in the composition range of 25 to 33 at% Ti. On the other hand, fine quasicrystalline phases are distributed in the amorphous matrix of the Ti-rich alloys. Crystallization temperatures and the hardness of the amorphous alloys were also examined.