bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disturbed Array Formation of Electrochemically Grown Self-Organised Nanostructures
Authors: Dierickx D.D. , Celis J.P. , Moshchalkov V.V. 
Published: April 2011

AbstractThe formation of electrochemically etched, self-organised nanostructures on aluminium enables the production of large area regular arrays in a fast and cost-effective way. These microstructures could form the basis to develop masks for subsequent materials deposition without the need for time consuming patterning techniques.The desired regular arrays result from a steady state interaction between the electrolyte and samples' surface under the influence of a cell potential. The type of array formed depends on this cell potential and shows an evolution from lines to dots.Although a gradual progress towards a regular lattice spanning large areas is expected, the presence of initial disturbances of the samples' surface or bulk distorts the final lattice considerably. In this work the modulation depth and type of the resultant nanostructures produced at different cell potentials are assessed in view of practical applications.
Corrosion Protection of Cu, Fe, Mn and Co Surfaces
Authors: Baglin J.E.E. , Kellock A.J. , Bardin T.T. , Karis T. , Keck D. 
Published: April 2011

AbstractThe mechanisms and effectiveness of corrosion protection provided by thin ion-beam carbon coatings on Cu, Fe, Mn and Co are discussed. A thin (# 10 Å) layer of protective carbon is produced on metal surfaces by ion-beam dissociation of adventitious or intentional hydrocarbon adsorbates. Below 200°C, oxidation is strongly inhibited, as is corrosion in a humid, sulphurous ambient. Above 200°C, the carbon layer may itself be destroyed by oxidation, due to catalytic action of the metal surface. Thicker PVD carbon (up to 60 Å) was not an effective corrosion barrier, even after ion irradiation. A technique for producing high integrity ion-beam carbon layers of high stability and durability is discussed.
High Density Recording on Conventionally Structured Magneto-Optical Disk by Magnetic Field Modulation
Authors: Kaneko M. , Fukumoto A. 
Published: April 2011

AbstractTwo recent topics on high density recording are reviewed in this paper on conventionally structured MO disk by magnetic field modulation. One topic is the MO disk with a capacity of 650 MB/ φ 64 mm. Using a light wavelength of 650 nm and an numerical aperture of an objective lens of 0.52, a track pitch of 0.95 μm and a bit length of 0.34 μm for (1,7) RLL coding has been applied to achieve 650 MB within a size of a Mini Disc(MD). Groove conditions such as the depth and groove duty in a 1.2-mm thick polycarbonate substrate are optimized to reduce the cross-talk from adjacent tracks. As a result, the recording power margin of ± 20% is obtained. The disk tilt margin is ± 0.82 deg and ± 0.63 deg in the radial and tangential direction, respectively.The other topics is land/groove recording using an optical phase shifter. A maximum carrier level and a minimum cross-talk are achieved simultaneously when an optical phase shifter is inserted into the optical path before an analyzer. The optimum phase shift is 40 deg for recording on land and -40 deg for recording in groove. Recording on 0.5 μm land/0.5 μm groove with 1.2-mm thick substrate is investigated with a bit length of 0.35 μm for (1,7) RLL code using a light wavelength of 693 nm and a numerical aperture of 0.55. MO recording using an optical phase shifter is promising for an areal density of 3.7 Gb/in2. Furthermore, when an optical phase shifter is applied to recording on 0.36 jim land/0.36 μm groove with a bit length of 0.258 μm, light wavelength of 642 nm, and NA of 0.7, a capability of 7.0 Gb/in2 using conventionally structured MO disk is shown.
Interaction of Ultrafine Titanium Oxide Particles with Layered Vanadium Oxide Hydrate
Authors: Kittaka S. , Matsuno K. , Takahara S. 
Published: April 2011

ABSTRACTVanadium pentoxide hydrate was pillared with ultrafine titanium dioxide particles to form expanded layered structure (∼20 A) and thereby forming microporous substance (diameter =∼10 A). Porous structure formation and adsorption of some toxic gases (CO and NO) were discussed.
Conducting Membranes and Coatings made from Redispersable Nanoscaled Crystalline SnO2:Sb Particles
Authors: Goebbert C. , Aegerter M. A. , Burgard D. , Nass R. , Schmidt H. 
Published: April 2011

ABSTRACTInorganic membranes prepared by the sol gel method are promising candidates for use as filters in separation processes. Conducting supported membranes and coatings have been produced from redispersable nanoscaled crystalline Sb-doped SnO2powders with a Sb content up to 5 mole % (with respect to Sn). The crystalline particles are monosized (≅4 nm) and fully redispersable in aqueous solution at pH ≥ 8 with a solid content up to 70 wt. %. By thermal treatment at different temperatures and times, the pore size diameter of the material can be adjusted from 4 to 20 nm with a very narrow pore size distribution (∼ ±1 nm) and a total porosity of 63 %, practically independent of the sintering parameters. Uniaxial pressed substrates present similar characteristics with however larger pore size distribution (±5 nm) and 80 % total porosity. Their resistance decreases with sintering temperature and time down to 4 Ω (800 °C 8 h). Fully dispersed aqueous solutions of the powder (25 wt. %) were used to prepare transparent conducting coatings on glass or ceramics by spin-coating. After thermal treatment (1 hour at 550 °C) single layers 200 nm thick exhibited a typical specific electrical resistance ρ = 2.5·10−2ωcm with transmission in the visible range measured against air of 90%.
Model Reaction Systems to Produce Monodisperse Colloids
Authors: Lee Kangtaek , McCormick Alon 
Published: April 2011

Monodispersely-sized spherical metal oxide particles have recently attracted growing attention for many industrial applications. In particulate coating applications, controlling the size and distribution of the starting colloid plays a crucial role in the final coating properties (1,2). In chromatography, both porous and nonporous monodispersely sized colloidal particles have been used as a column-packing material (3,4). Monodisperse particles can also be used as a startingn material in a ceramic processing to make ceramic materials with uniform properties for mechanical, refractory, and catalysis applications.Even though various monodisperse metal oxide colloids are already widely used in industry, predicting and controlling the particle size distribution is frequently more dependent on experience and ingenuity rather than on modeling. There is nothing wrong with empiricism, but models can help to achieve process control, optimization, and flexibility. We have sought to assess what combination of processes in solution (both reactive and aggregative) need to be modeled, and in doing so we have found a number of very useful references that give insight into 1) the mechanism of the particle formation and growth, and 2) the effect of reaction parameters on the final size distribution by using both experimental and numerical techniques. Understanding these should allow us to intelligently design a new process in order to make particles with the desired size and distribution. In this short contribution we hope that it will be of service to provide a brief overview of some key work that may yield itself to modeling. This review is not intended to be comprehensive; instead, we have selected work that shows features that one hopes should be captured by meaningful models.
The Effect of Parent Metal Properties on the Performance of Lattice Block MaterialTM
Authors: Renauld M. L. , Giamei A. F. , Thompson M. S. , Priluck J. 
Published: April 2011

ABSTRACTLattice Block MaterialTM, or LBMTM is a unique lightweight structure consisting of repeated cells with an internal node connected to, in the most common configuration, 14 ligaments. In its metallic version, this product is available in a variety of castable metals including aluminum alloys, copper alloys, nickel alloys and steels. The relationship between LBMTM structural performance (strength and stiffness) and parent metal properties is investigated using compression tests in three primary orientations and 3-pt. bend tests. Analytical assessment of the LBMTM via finite element analysis shows reasonable agreement with experimental findings and provides predictions for LBMTM capabilities with different materials, unit cell sizes and ligament geometries.
Reduction In Young's Modulus Of Aluminum Foams Due To Cell Wall Curvature And Corrugation
Authors: Sanders W. , Gibson L. J. 
Published: April 2011

ABSTRACTMeasurements of the Young's modulus and compressive strength of several closedcell aluminum foams indicate that they are lower than expected from models for foam behaviour. Microstructural characterization has revealed that there are a number of defects in the cell structure which may contribute to the reduction in mechanical properties. These include: cell wall curvature, cell wall corrugations, density variations and non-equiaxed cell shape. Finite element analysis of a closed-cell tetrakaidecahedral unit cell with idealized curved or corrugated cell walls indicates that these two types of defects can reduce the Young's modulus and compressive strength by up to 70%. In this paper we report the results of measurements of the curvature of the cell walls and of the amplitude and frequency of corrugations in the cell walls and use simple bounds to estimate the reduction in modulus that they are responsible for.
A Comparison of Mos Devices with In-Situ Boron Doped Polysilicon and Poly Sige Gates Deposited in an Rtcvd System Using S12H6 and B2H6 Gas Mixture
Authors: Mirabedini M. R. , Li V. Z-Q , Acker A. R. , Kuehn R. T. , Venables D. , Öztürk M. C. , Wortman J. J. 
Published: April 2011

ABSTRACTIn this work, in-situ doped polysilicon and poly-SiGe films have been used as the gate material for the fabrication of MOS devices to evaluate their respective performances. These films were deposited in an RTCVD system using a Si2H6 and GeH4 gas mixture. MOS capacitors with 45 Å thick gate oxides and polysilicon/poly-SiGe gates were subjected to different anneals to study boron penetration. SIMS analysis and flat band voltage measurements showed much lower boron penetration for devices with poly-SiGe gates than for devices with polysilicon gates. In addition, C-V measurements showed no poly depletion effects for poly-SiGe gates while polysilicon gates had a depletion effect of about 8%. A comparison of resistivities of these films showed a low resistivity of 1 mΩ-cm for poly-SiGe films versus 3 mΩ-cm for polysilicon films after an anneal at 950 °C for 30 seconds.
The Effect Of Chamber Components On Wafer Temperature Response In An Rtp System
Authors: Acharya N. , Timans P. J. 
Published: April 2011

ABSTRACTIn recent years, simulation techniques have emerged as useful tools for the design of semiconductor equipment. However, the need for rapid assessment of potential designs stretches the capability of even the most advanced tools currently available to the limit. In this paper, a simplified model of a rapid thermal processing (RTP) system that significantly reduces the execution time is presented. The model is based on a coupling of semi-analytical expressions for radiation fluxes with a one-dimensional finite element heat transfer model for wafer and slip-free ring temperatures. Results showing the effects of plate reflectivity and slip-free ring emissivity on wafer temperature are presented. It is shown that the simplified model yields results that are in agreement with detailed two-dimensional simulations of the same geometry.
Structural Studies of Silver/Permalloy and Copper/Permalloy GMR Spin Valve Multilayers
Authors: Geng H. , Zhu W. , Heckman J.W. , Loloee R. , Pratt W.P. , Bass J. , Crimp M.A. 
Published: April 2011

AbstractGiant magnetoresistance (GMR) spin valves of the form Ag/Py/Ag/Py/FeMn and Cu/FeMn/Py/Cu/Py have been studied using conventional and high-resolution electron microscopy complemented with fast Fourier transform (FFT) diffractogram analysis. Cross-sectional TEM thin foil samples were prepared in order to characterize the layer structures and interfaces. In the Ag/Py system, we have examined a simple spin valve, part of which was grown on the Nb contact and part directly on the Si substrate. The spin valve displays a polycrystalline structure when grown on the Nb contact. In contrast, when grown directly on the Si substrate, the first Ag layer of the spin valve grew as a continuous epitaxial single crystal while the rest of the layers were polycrystalline. Two Cu/Py spin valves, grown on Nb, with 30 nm and 3 nm thick Py layers have been investigated. TEM images reveal good contrast between the Nb contacts and the spin valves, but weak contrast between the individual spin valve layers. Both spin valves displayed columnar, polycrystalline grain structures. HRTEM analysis indicates some non-equilibrium structures exist in the spin valve layers.
Modeling of Substrate Bias Effect on the Compositional Variations in Sputter-Deposited TiB2+x Diffusion Barrier Thin Films
Authors: Sinder M. , Sade G. , Pelleg J. 
Published: April 2011

AbstractSputter-deposited titanium boride diffusion barrier layers have been found to be boron enriched when r.f substrate bias was applied. In the present experiments titanium boride was deposited by co-sputtering from Ti and B pure targets in Ar discharge and the voltage of r.f. self-bias was in the range of 100 – 250 V. Films deposited were found by Auger electron spectroscopy to be B enriched with increasing bias voltage at constant Ti and B sputtering rates. A model of the sputter-deposition conditions was developed to predict the composition and the thickness of the growing film. The model explains the experimental results indicating that B enrichment is mainly a result of differential resputtering of the components from the growing film by energetic Ar ions captured from the r.f discharge.
Computational Modelling of Ring-Shaped Magnetic Domains
Authors: Gal'tsev A.F. , Pokazan'ev V.G. , Yalishev Y.I. 
Published: April 2011

AbstractA theoretical research of static stability of peculiar localized domain structures (LDS) in a thin magnetic film with the perpendicular anisotropy is presented. The model describes a system consisting of cylindrical magnetic domain (CMD) and several concentric ring-shaped domains. Such structures arise under influence of the external low frequency (100–1000 Hz) magnetic field applied perpendicular to the film plane and were observed experimentally in 1992. Non-linear singular integro-differential equation for a magnetization distribution is provided by a minimization condition for the system's complete energy local density. Energy dependencies on geometry parameters are calculated numerically. The conditions of magnetostatic stabilization of the simplest CMD-ring system, as well as some of its dynamical properties, are discussed in detail on this basis.
Localized Surface Instabilities of Stressed Solids
Authors: Colin J. , Grilhé J. , Junqua N. 
Published: April 2011

AbstractLocalized instabilities formation on the free surface of solids has been studied when sources of non-homogeneous stress such as dislocations or precipitates are present in the bulk. This formalism of localized perturbations has been used to describe the butterfly transformation of cubic precipitates in superalloys and the contraction of rectangular specimens under stress.
Abrasion Damage to Lightguide Fiber Surfaces
Authors: Kurkjian C. R. , Matthewson M. J. , Chaudhri M. M. 
Published: April 2011

AbstractThe two general types of strength-reducing defects most commonly found in lightguide fibers are those due to chemical interactions of refractory particles with the hot glass and those due to mechanical damage resulting from indentation or scratching. In this paper we review some work on the mechanical damage in silica lightguide fibers and some of the approaches which have been taken to simplify the study of such damage. We are reminded that the indentation and scratching behavior of silica glass is not simple and that in all probability there are a variety of different types of flaws which may have different fatigue and aging behavior, and therefore result in different lifetimes. It is therefore suggested that either the actual proof test level flaws, or at least a wide variety of synthetic flaws, must be studied in order to develop sufficient background and experience to confidently predict fiber lifetimes.
High Speed Strength Testing of Optical Fiber
Authors: Glaesemann G. S. , Clark D. A. , Hanson T. A. , Wissuchek D. J. 
Published: April 2011

AbstractOptical fiber models for mechanical reliability require that the initial strength and crack growth parameters be measured. High speed testing allows one to investigate and model common high-speed processing events during fiber processing such as proof testing, coloring and cabling. In this study stressing rates ranging from 7×10−6 GPa/s to 1.5 TPa/s were accomplished using a universal testing machine, belt slide and pneumatic piston. When plotted in typical dynamic fatigue fashion the data shows curvature at the faster stressing rates. The presence of region II type crack growth is suggested as a possible explanation for this curvature. A multi-region crack growth model is used to extract crack growth parameters that are used to make comparisons with crack velocity results on bulk glass.
Reliability of Linbo. Based Integrated Optical Waveguide Devices for Fiber Communication Systems
Authors: Nagata Hirotoshi , Mitsugi Naoki , Higuma Kaoru , Ichikawa Junichiro , Sakamoto Toshihiro , Fujino Tetsuya , Shinriki Takashi 
Published: April 2011

AbstractIncreasing demands for LiNbO3 (LN) optical waveguide devices installed into submarine and terrestrial fiber communication systems necessitate that high quality and long-term reliability (over 20 years) be established. In addition to general requirements for reliability in electrooptical devices, the LN devices need to assure of the dc-drift phenomena in the optical output signal. The dc-drift is caused by the complex electrical nature of constituent device materials; i.e. LN substrates and SiO2 buffer layers on LN. Results of theoretical and experimental investigations of the suppression of dc-drift are applied to the design of practical LN devices, and the devices have been in service for 4 years, as of this moment, without any failure. Here, problems on the dc-drift are discussed from the viewpoints of device reliability and actual fabrication processes.
Pyroelectric and Piezoelectric Properties of Gan-Based Materials
Authors: Shur M. S. , Bykhovski A. D. , Gaska R. 
Published: April 2011

AbstractWe review pyroelectric and piezoelectric properties of GaN-based materials. Pyroelectric effects in GaN have been studied in two different regimes: (i) uniform sample heating regime and (ii) under applied temperature gradient along the sample. The modeling results show that the pyroelectric coefficient, Pv, in GaN (for c-axis along the contacts) can reach 7x105 V/m-K (compared to Pv = 5x105 V/m-K for the best-known high temperature pyroelectric/piezoelectric material LiTaO3). This points to a high potential of GaN-based sensors for high temperature pyroelectronics. Piezoelectric effects strongly affect the performance of electronic and light-emitting devices based on III-N materials. Piezoelectrically induced charge in heterostructures can be as large as 3 to 4x1013 cm-2. Hence, strong lattice polarization effects provide unique possibilities for utilizing GaN-based materials in high temperature piezoelectronics and for their applications in pyroelectric detectors.
Luminescence from Erbium-Doped Gallium Nitride Thin Films
Authors: Zavadat J. M. , Thaik Myo , Hòmmerich U. , MacKenzie J. D. , Abernathy C. R. , Ren F. , Shen H. , Pamulapati J. , Jiang H. , Lin J. , Wilsont R.G. 
Published: April 2011

AbstractThe III-V nitride semiconductors appear to be excellent host materials for optical device applications involving thin films doped with rare earth atoms. In particular, GaN epilayers doped with Er ions have shown a highly reduced thermal quenching of the Er luminescence intensity from cryogenic to elevated temperatures. The remarkable thermal stability of the light emission may be due to the large energy bandgap of the material, as well as to the optical inactivity of material defects in the GaN film. In this paper we present recent developments concerning the luminescence characteristics of Er-doped GaN thins films. We have used two methods for doping GaN films with Er ions, ion implantation and in-situ incorporation during gas source metal-organic molecular beam epitaxy (MOMBE). Bandedge (at ∼ 0.34 μm) and infrared (at ∼ 1.54 μm) photoluminescence (PL) spectra have been measured for both types of Er-doped GaN films. Considerably different emission spectra have been observed depending upon the incorporation method and the heat treatment procedure. In situ Er-doped GaN layers have been processed into hybrid light emitting devices and emission spectra at 1.54 Pm have been measured.
Composition Dependence of the Band Gap Energy of InxGal-xN Layers on GaN (x≤0.15) Grown by Metal-Organic Chemical Vapor Deposition
Authors: Wagner J. , Ramakrishnan A. , Behr D. , Maier M. , Herres N. , Kunzer M. , Obloh H. , Bachem K.-H. 
Published: April 2011

AbstractWe report on the composition dependence of the band gap energy of strained hexagonal InGal-,N layers on GaN with x≤0.15, grown by metal-organic chemical vapor deposition on sapphire substrates. The composition of the (InGa)N was determined by secondary ion mass spectroscopy. High-resolution X-ray diffraction measurements confirmed that the (InGa)N layers with typical thicknesses of 30 nm are pseudomorphically strained to the in-plane lattice parameter of the underlying GaN. Room-temperature photoreflection spectroscopy and spectroscopic ellipsometry were used to determine the (InGa)N band gap energy. The composition dependence of the band gap energy of the strained (InGa)N layers was found to be given by EG(x)=3.43-3.28.x (eV) for x≤0.15. When correcting for the strain induced shift of the fundamental energy gap, a bowing parameter of 3.2 eV was obtained for the composition dependence of the gap energy of unstrained (InGa)N.
Domain Structure of Thick GaN Layers Grown by Hydride Vapor Phase Epitaxy
Authors: Paskova T. , Svedberg E.B. , Madsen L.D. , Yakimova R. , Ivanov I.G. , Henry A. , Monemar B. 
Published: April 2011

AbstractThe crystal structure and surface morphology of hydride vapour phase epitaxy grown thick (12-105 μm) GaN layers have been investigated as a function of growth rate using several structure sensitive techniques like atomic force microscopy (AFM), x-ray diffraction (XRD) in ω-2Θ and ω-rocking curve measurements as well as low temperature photoluminescence (PL). PL and XRD measurements reveal rather narrow lines: full width at half maximum (FWHM) values of the strongest donor-bound exciton line are in the range from 6.0 to1.8 meV and ω-2Θ FWHM values are between 80 and 23 arcsec indicating good structural quality of the films. The ω-rocking curves show a single peak for the thinnest films with a FWIM of 250 arcsec and multiple peaks with FWHIM of about 250-350 arcsec in thicker films indicating the formation of several high-quality domains when increasing either thickness or growth rate. Optical microscopy and AFM images reveal a domain type of morphology and also show an appearance of spiral hillocks in layers grown at growth rates exceeding a critical value. We interpret these results as dominating 2D multilayer growth at low growth rates, and competing 2D multilayer and spiral growth mechanisms at high growth rates.