bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Dynamics Simulation of Radiation-Induced Amorphization of the Ordered Compound NiZr2
Authors: Devanathan R. , Lami N. Q. , Okamoto P. R. , Meshii M. 
Published: March 2011

ABSTRACTWe have studied the electron irradiation-induced amorphization of the ordered intermetallic compound NizR2 by molecular dynamics simulations in conjunction with embedded-atom potentials. Randomly chosen Frenkel pairs and chemical disorder were introduced into the system in separate processes. In both cases, the energy and volume of the system rose above the corresponding levels of a quenched liquid and the calculated diffraction patterns indicated the occurence of a crystalline-to-amorphous transition. In addition, the average shear elastic constant fell to about 50% of its value in the perfect crystal and the system became elastically isotropie. These results indicate that NiZr2 can be amorphized by chemical disorder as well as Frenkel pairs and are in good agreement with experimental observations.
Ion Beam Induced Crystallization of Amorphous Si from NiSi2 Precipitates: An In Situ Study
Authors: Fortuna F. , Ruault M. -O. , Bernas H. , Gu H. , Colliex C. 
Published: March 2011

ABSTRACTBy first growing NiSi2 precipitates in a-Si and then irradiating with a 150 keV Si beam, we have studied ion beam induced epitaxial crystallization (IBIEC) of Si initiated at a-Si/NiSi2 precipitate interfaces. The growth shape and its temperature dependence are studied in-beam via in situ transmission electron microscopy. Interface roughening is evidenced. Preliminary results for the Co-Si system are also reported.
Low Energy Fluoroboron Ion Beam Interaction with Silicon Single Crystals
Authors: Huang L. J. , Lau W. M. , Mitchell I. V. , Lee S.-T. 
Published: March 2011

ABSTRACTFluoroboron (BF2+) ion implantation into silicon is frequently used for fabrication of shallow junctions. For scaling down of the junction dimensions, one of the efficient approaches is to lower the implantation energy. This work reports fluoroboron ion interactions with (100) oriented silicon at 10 to 500 eV ion energy. Ion bombardment was carried out using a mass-separated BF2+ ion beam in an ultrahigh vacuum low energy ion beam system. The temperature of the silicon crystal during bombardment was kept either at room temperature or 500°C. The reactions (both etching and incorporation) were characterized by x-ray photoemission spectroscopy (XPS), Rutherford backscattering (RBS) and Raman scattering. The results show that BF2+ ions dissociated on the silicon surface at an energy as low as 10 eV and most of fluorine segregated to the surface and desorbed. Both the physical and chemical etching rate of the beam were energy dependent but much lower than the accumulation rate. For beam fluences higher than 1 × 1018/cm2, continuous amorphous boron films were deposited on silicon.
Photo-Assisted Chemical Beam Epitaxy of II-VI Semiconductors
Authors: Ho E. , Coronado G. A. , Kolodziejski L. A. 
Published: March 2011

ABSTRACTPhoto-assisted epitaxy is a versatile growth technique which allows in situ modification of surface chemical reactions. Under appropriate growth conditions the surface stoichiometry can be tuned by selectively desorbing surface species, or by decomposing particular molecular species, or by affecting the reaction rate constant of a chemical process. A potential application of laser-assisted growth rate enhancement or growth rate retardation is in the area of maskless selective area epitaxy. We have investigated the effect of photons on the growth of ZnSe by solid and gaseous source molecular beam epitaxy using various combination of sources. Significant growth rate enhancement (up to 20x), as well as growth rate suppression (as much as 70%), have been observed depending on the sources employed. In all cases, the laser power density remained low (∼200 mW/cm2), and the creation of photo-generated carriers was found to be required. An electron beam incident to the surface has a similar effect and increased the growth rate.
i-CxSiyOzHw Films Formed by Ion Beam Assisted Deposition
Authors: Fountzoulas C. G. , Demaree J. D. , Kosik W. E. , Franzen W. , Croft W. , Hirvonen J. K. 
Published: March 2011

ABSTRACTi-CxSiyOzHw films were formed by thermal evaporation of a tetraphenyl-tetramethyl-trisiloxane diffusion pump oil onto silicon and steel substrates with simultaneous bombardment of the growing film with 40 keV Ar+ ions to decompose the (C6H5)4(CH3)4Si3O2 molecules. Both the current density of the ion beam and the oil arrival rate were varied to produce hard, adhesive films on room temperature substrates, with densities ranging from 1.4 to 2.3 g/cm3 and Knoop microhardness values (at 15 g load) from 1000 to 2100. Unlubricated friction coefficients against a 440C steel ball with a 50 g load ranged from 0.03 to 0.40, depending on deposition conditions, and all films were more wear-resistant than the substrate materials. The films were examined with RBS, hydrogen forward recoil scattering, SEM, TEM, photon tunneling microscopy, electron diffraction, and ellipsometry to ascertain and correlate their chemical compositions and microstructures with their mechanical/chemical properties (microhardness, adhesion, friction and wear).
Ion and Electron Beam Processing of Condensed Molecular Solids to Form Thin Films
Authors: Ruckman M. W. , Mowlem J. K. , Moore J. F. , Strongin D. R. , Strongin M. 
Published: March 2011

ABSTRACTElectron and ion beams can be used to deposit thin films and etch surfaces using gas phase precursors. However, the generation of undesirable gas phase products and the diffusion of the reactive species beyond the region irradiated by the electron or ion beam can limit selectivity. Tn this paper, the feasibility of processing condensed precursors such as diborane, tri-methyl aluminum, ammonia and water at 78 K with low energy (100–1000 eV) electron and ion beams (Ar+, N2+ and H2+) ranging in current density from 50 nA to several μ a per cm2 is examined. It was found that boron, boron nitride and stoichiometric aluminum oxide films could be deposited from the condensed volatile species using charged particle beams and some of the physical and chemical aspects and limitations of this new technique are discussed.
Structural Change of Graphite During Electron Irradiation
Authors: Koike J. , Pedraza D. F. 
Published: March 2011

ABSTRACTHighly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. All the results obtained here consistently indicated die absence of long-range order periodicity in the basal plane and the loose retention of the c-axis periodicity. The structure was modeled based on a mixture of sixfold and non-sixfold atom rings. The formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.
Synthesis of Ti2N-TiSi2 Layers by One-Step Excimer Laser Irradiation
Authors: Majni Giuseppe , Mengucci P. , Barucca G. , Leggieri G. , Luches A. 
Published: March 2011

ABSTRACTIn the present work a novel approach to suicide and nitride formation on the surface of silicon single crystals wafers is reported. The compound growth occurs directly in the place of interest as a result of a laser promoted chemical reaction. Results indicate that it is possible to obtain a titanium nitride layer superimposed on a titanium suicide film with a single-step laser irradiation process. The thickness of the suicide and nitride layers can be adjusted by a proper choice of the laser fluence and number of subsequent pulses.
Ultrafast Laser Superheating of Metal Surfaces
Authors: Elsayed H. E. , Herman J. W. , Murphy E. A. 
Published: March 2011

ABSTRACTReflection high-energy electron diffraction with ∼200-ps temporal resolution is used to study the structural dynamics of the closed-packed surfaces of single crystals of lead and bismuth subjected to ultrafast laser heating. By monitoring the temporal evolution of the diffraction streak intensity, information is obtained on the mean-square vibrational amplitude of the surface atoms and the structural integrity of the surface. Pb(lll) is observed to superheat by ∼120 k above the bulk melting point. With increased heating laser intensity, melting is observed to occur subsequent to superheating. Superheating of Bi(0001) by ∼85 K was also observed.
Laser Heating of Substrate by Multi-Beam Irradiation
Authors: Lu Y. F. 
Published: March 2011

ABSTRACTA general model is derived for computing the temperature profile induced by multi-beam laser irradiation in a semi-infinite substrate. The model is then applied to calculate 2-beam irradiation induced temperature rise in substrate. From this model, it is possibLe to calculate the temperature profile induced by multi-beam irradiation in substrate. The calculated results show that the double-Gaussian beam has advantages of narrow temperature profile and low heat flow intensity. Flatly-topped temperature profiles can be obtained by converting the Gaussian laser beam.
Interaction Between Intense Nd:Yag Laser Pulse and a Metal
Authors: Ito Yoshiro , Kametani Michiko , Imai Jun-Ichi , Nakamura Susumu 
Published: March 2011

ABSTRACTEnergy absorption of intense Nd:YAG laser pulse at the surface of aluminum was measured as a function of laser energy fluence φ by pbotoacoustic method using a piezoelectric transducer. Luminescence spectra from laser induced plume were measured. A Q-switched Nd:YAG laser which generate pulses of 8 ns duration was used.Pbotoacoustic signal intensity I increased according to the laser pulse energy at low fluences. At a constant pulse energy, the I was a function of the energy fluence φ and had a threshold φth, When the φ was lower than the φth, the I was constant and corresponded to the absorption coefficient of the metal. Above the φth, it approached the maximum I/max and then began to decrease with further increase in the φ. If we represent the relative change in I at different pulse energies as the normalized intensity I/Imax. a universal curve was obtained.Below the φth, the process was normal photon absorption by the metal. Damage left on the irradiated surface became evident above the φth, Above the φth and below the Imax. surface temperature increased high enough to form melt and the photo-absorption coefficient would increase during one laser pulse. A shock wave would be formed at the surface and contribute to the increase of the I. Higher φ than at the Imax some processes which inhibit the energy absorption would occur and the I decreased.
Neutral Beam Source Design and Beam Kinetic Energy Activated SiO2 Etching
Authors: Chen Lee , Sekiguchi Akihisa , Podlesnik Dragan 
Published: March 2011

ABSTRACTAn unique method is used to produce a low energy nonthermalized fast neutral radical beam wliich can activate the SiO2 surface for chemical reaction at the desired incident energy. The fast neutral beam energy is continuously adjustable (2eV<Ek<200eV) and the beam flux is typically 5×1015cm−2 sec−1(∼4L). An uniform large diameter plasma is also made for the production of neutral beam covering 5”wafer and larger. Large diameter neutral beam single wafer reactor is feasible with off-the-shelf pumping technology.
Effects of Additive Gas on SiO2 Etching
Authors: Miyakawa Yasuhiro , Hashimoto Jun , Ikegami Naokatsu , Kanamori Jun 
Published: March 2011

ABSTRACTPrecise control of critical dimension(CD) loss (defined as the length of the top of contact hole minus the bottom of resist in this paper) and etched profile of contact holes is a key technology in the fabrication of Ultra Large Scaled Integrated Circuit(ULSI). In case of fine contact hole etching, small CD loss and vertical profile is essential. We have found out that N2 addition to Ar/CHF3/CF4 sharpens etched profile with CD loss kept small. And N2 addition also increases etch rate without a heavy deterioration of selectivity of SiO2 versus heavily doped n-type poly cry stall ine Si(n+ poly Si). Mechanisms of changes in etching characteristics have been investigated and discussed with the emphasis on adlayer formed on etched surface.
Sub-Micron Mesotaxial CoSi2 Wires
Authors: Liddle J. Alex , Zimmerman Neil M. , White Alice E. , Short Ken T. , Fetter Linus 
Published: March 2011

ABSTRACTTransition metal suicides are receiving an increasing amount of attention as materials for VLSI interconnects because of their low resistivities and ease of integration with silicon. A recently invented technique, mesotaxy, allows the production of buried single-crystal suicide layers in silicon.Buried suicide layers made by implantation into (100) Si wafers can be patterned by restricting the implant with an oxide mask, giving great flexibility in the types of features that can be produced. We have fabricated simple microstructures to investigate the formation and properties of mesotaxial CoSi2. Wires of constant dose but varying widths exhibit a transition in morphology from {111} faceted wires to largely (100) faceted layers. After annealing for prolonged periods, the finer wires show the effects of coarsening. We have also observed the movement of a significant amount of Co from the oxide implant mask into the substrate during these anneals. The wires show greatly improved thermal stability compared to polycrystalline suicides formed by deposition.1
Heat Transfer in Melt Spinning Cooling Belts and Drums
Authors: Swanson B. W. , Williams R. S. , Draper R. 
Published: March 2011

ABSTRACTFourier series solutions have been obtained for the temperature distributions in melt spinning cooling belts and drums. These solutions have been used to determine drum and belt designs for producing 0.050 inch steel sheet. This paper discusses thermal design parameters for cooling drums used in melt spinning rapid solidification.
Melt-Spinning a Commercial Aluminium Alloy
Authors: Willis T C , Cantor B 
Published: March 2011

ABSTRACTA commercial aluminium alloy (3004) has been melt-spun on both an aluminium and a copper substrate. The meltspinning conditions have been varied in order to determine the optimum spinning parameteis for the apparatus used. The resulting ribbon has been examined by optical microscopy, transmission electron microscopy and anodization to show differences in grain structure and second phase distribution between the as-received rolled sheet and the melt-spun ribbon. X-ray diffractometry has been used to obtain information about the different intermetallic phases present in the sheet and ribbon, and peak heights of X-ray diffractometer traces have also been used to indicate textures present in the ribbons spun on aluminium and copper substrates.
Dynamic Compaction of Al Alloys
Authors: Sears J.W. , Muddle B.C. , Fraser H.L. 
Published: March 2011

ABSTRACTPowders of Al alloy 7091 have been consolidated by means of dynamic compaction. The dependence of density and hardness on projectile velocity has been determined. The resulting as-compacted material has been characterized using analytical transmission electron microscopy and evidence of interparticle melting observed. The microstructural responseof the compacted material to heat treatment at 523 and 723°K has been investigated.
Corrosion Resistance Of fe- and Ni- Based Metallic Glasses
Authors: Reinders B.-O. , Bergmann H. W. 
Published: March 2011

ABSTRACTThe corrosion behaviour in liquid electrolytes were investigated for some Fe- and Ni-based metallic glasses varying pH-value, electrolyte temperature and heat treatment. For some (Fe100-xMx)83B17 glasses the high temperature oxidation behaviour was studied.
Kinetics and Morphology in Rapid Solidification
Authors: Bergmann H. W. , Fritsch H. U. 
Published: March 2011

ABSTRACTThe important parameters in all descriptions of the kinetics of crystallization behaviour are the differences in free energy Δgv between the liquid (glassy) phase and the various stable and metastable crystalline phases. The various quenching techniques can be subdivided into those in which the cooling rate is determined by the heat diffusivity and those in which the heat transfer coefficient is important. The temperature gradient and the solidification rates are different in the two cases. An additional difference is the nucleation rate which is dependent on the degree of undercooling.
High Strength Copper-Nickel Alloys Made by Rapid Solidification Technology (Rst)
Authors: Panchanathan V. 
Published: March 2011

ABSTRACTRapid solidification technology (RST) has been shown to offer outstanding prospects of processing new cost-effective engineering materials with superior properties. There has as yet been only limited effort in the use of RST to synthesize new and improved copper-base alloys. A detailed investigation has been carried out to develop new coppernickel alloys by RST. These alloys find extensive use as condenser tubes, seamless tubes, etc.New alloy systems suitable for processing by RST have been identified. These systems are as follows:a) Cu-Ni-Bb) Cu-Ni-Al-Bc) Cu-Ni-Cr-Bd) Cu-Ni-Al-Cr-BThe preferred composition ranges and maximum attainable hardness for each system are given. It is of interest to note that the maximum hardness values attained for this system are around 500 Kg/mm2 which is much higher than the hardness of the conventional copper-nickel alloys.
Precipitation Strengthening Of Rapidly Solidified Austenitic Stainless Steels
Authors: Megusar J. , Chaudhry A. , Imeson D. , Grant N. J. 
Published: March 2011

ABSTRACTPrecipitation kinetics was studied in a rapidly solidified 316 stainless steel containing 0.22% C and 1% Ti. A high density of fine TiC particles was obtained by annealing at 923 to 973 K. An increase in recrystallization temperature and room temperature yield strength was observed as compared with the rapidly solidified 316 stainless steel with a nominal carbon and titanium content. An extension of solid solubility by rapid solidification thus offers a potential for developing precipitation strengthened austenitic stainless steels to improve structural and mechanical stability and likely the irradiation resistance.
Metallic Glass Cladding Of High Strength Steel Using Electron Beams
Authors: Mawella K J A , Honeycombe R W K 
Published: March 2011

ABSTRACTThe effects of electron beam surface melting on a high strength Ni-Cr-Mo-V steel are first described with particular reference to the refined microstructure and the increased surface hardness. Similar experiments on an Fe80P13C7 alloy are described, in which surface amorphous layers were produced leading to hardnesses around 910VPN at the surface up to 1250VPN further in and falling to 650VPN in the as-cast crystalline substrate.Metallic glass cladding of the steel was achieved by coating the steel surface with thin layers of powdered Fe80P13C7 alloy, and traversing with an electron beam sufficient to fuse the powder layer. Process variables including beam power and thickness of powder layer were examined and optimum conditions for glass formation in the surface layer were determined. These layers were examined by optical and electron microscopy, X-ray diffractometry and energy dispersive X-ray analysis. The microhardness variation with distance from the surface was also determined and found to be in the range 880–1150VPN.
New Phenokena in Electron Beam Glazing
Authors: Strutt P. R. , LeMAY J. , Tauqir A. 
Published: March 2011

ABSTRACTLinear heat source surface melting studies have been carried out using a 1 to 15 kH oscillating beam incident on a steel substrate to produce a 3 to 35mm wide rapidly solidified strip of material at rates ranging from 1 to 100 cm.s−1. A simple relationship betweenmelt depth, power, and substrate velocity (V) has been determined at low values of V; limited results at higher velocities appear to follow the same relationship. A serendipitous discovery was the effect of prior surface homogenization treatment on the geometrical and microstructural uniformity of the subsequently formed rapidly solidified layers. This pre-treatment resulted in the formation of thin layers of uniform thickness under the most rapid processing condition (V = 100 cm.s−l). Omission of pre-treatnent resulted in irregular and sometimes discontinuous surface layers. In the case of a high speed steel of near peritectic composition (M2)pre-treatment resulted in the almost complete elimination of massive austenitic region within the dominant ferrite phase.
Electron Beam Glazing of Hardfacing Alloys
Authors: Kurup M. , Tauqir A. , Strutt P. R. , Kear B. H. 
Published: March 2011

ABSTRACTElectron beam glazing has been used to reprocess hardfacing deposits of conventional Stellite 6 alloy, and TiC, TiB2 particle strengthened Stellite 6. By varying the scanning mode and power density, a wide variety of microstructures have been developed, with significant increases in hardness. Single-pass line source scanning produces a distribution of moderately sized carbides (2–5μm) in a dendritic matrix, whereas multi-pass processing gives a more homogeneous refined microstructure with submicron carbides. Point source scanning, in contrast, produces the most refined microstructures. Effective control of the carbide distribution, including both fine and coarse carbides, may be the key to tailoring the microstructure for specific wear applications.
Estimation of Surface Diffusion Length from AFM Images of Faceted GaAs(111) Homoepitaxial Films
Authors: Yang K. , Schowalter L. J. , Thundat T. G. 
Published: March 2011

ABSTRACTGaAs films grown on exact (111) substrates in the reconstruction regime always show facets. We have studied the surfaces of these films with an atomic force microscope. The facets are composed of vicinal surfaces which are tilted by small angles (∼ 2°) from the exact (111) plane. From the geometry of the facet, average displacement of adatoms is calculated. The results indicate that the diffusion length under the growth condition is more than 0.2 μm.
Atomic Force Microscopy of Growth Features on Epitaxial CdHgTe Films
Authors: Aindow M. , Cheng T. T. , Jones I. P. , Astles M. G. , Williams D. J. 
Published: March 2011

ABSTRACTAtomic Force Microscopy has been used to observe the details of surface morphology on CdxHg1-xTe epitaxial films. On films grown by liquid phase epitaxy (LPE), tiered pyramidal features were observed and these are consistent with enhanced nucleation and growth at emergent edge dislocations which thread through from subgrain boundaries in the substrate. On films grown by metal-organic vapour phase epitaxy (MOVPE) using the interdiffused multilayer process (IMP), terraces and steps are observed as expected but the step edges are decorated. It is suggested that this corresponds to the deposition of one binary layer in Volmer-Weber mode.
Microstructure - Roughness Interelation in Ru/C and Ru/B4C X-RAY Multilayers
Authors: Nguyen Tai D. , Gronsky Ronald , Kortricht Jeffrey B. 
Published: March 2011

ABSTRACTX-ray specular and non-specular scattering, and high-resolution transmission electron microscopy (HRTEM) were performed to study the evolution of the microstructures and interfacial roughness in Ru/C and RU/B4C multilayers upon annealing. The microstructure of the approximately 1.4 nm thick Ru layers in the as-prepared 3.5 nm period multilayers is predominantly amorphous. The Ru layers in the Ru/B4C multilayer show RuB2nano-crystallites after annealing at 600°C for one hour, while those in the Ru/C multilayer crystallize to form hexagonal Ru crystallites. Cross-sectional HRTEM of the annealed Ru/C multilayer also shows agglomeration of the Ru layers. Non-specular measurements of the Ru/C multilayers indicate an enhanced uncorrelated roughness upon annealing. The diffuse component in the as-prepared and annealed RU/B4C multilayers shows insignificant changes. The increase in interfacial roughness in the Ru/C multilayer results from agglomeration of the Ru after annealing, consistent with HRTEM observation.