bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of Tft Characteristics by Using Controlled Grains
Authors: Takeuchi F. , Suga K. , Mishima Y. , Sasaki N. 
Published: April 2011

AbstractWe fabricated TFTs on a glass substrate using poly-Si films crystallized by an excimer laser with a SiO2 capping pattern placed exactly on the channel regions. This process greatly improves the uniformity of the TFT characteristics compared to conventional excimer laser-crystallized poly-Si TFTs, because the capping pattern controls nucleation and produces grains that are aligned along the capping pattern. However, the average mobility produced by the capping method is not as good as that produced by the conventional method. This study clarified that a thermal gradient can control grain structure and is effective in achieving uniformity, and that the maximum temperature of molten Si must be increased to obtain higher mobility.
A Possible Production Technique for Modulation Doped Sige Heterostructures
Authors: Rosenblad C. , Kummer M. , Müller E. , Hackbarth T. , Känel H. Von 
Published: April 2011

AbstractThe SiGe graded buffer layer is one of the most promising virtual substrates for future Si based high speed devices. The production of the SiGe buffer layer is, however, hampered by the time consumed by the synthesis of the several μm thick epitaxial layer. Low energy plasma enhanced chemical vapour deposition (LEPECVD) is a growth technique developed for low temperature epitaxy at high rates. Here we study the possibility to combine LEP-ECVD for graded SiGe buffer layer growth with other techniques for the growth of the electrically active layer.
Study of Strain Relaxation in Epitaxial Structure Ge0.2 Si0.8/Si At Thermo-Implantation Treatment by Ion Beam Channeling
Authors: Vyatkin A. F. , Egorov V. K. , Egorov E. V. 
Published: April 2011

AbstractStrain relaxation in epitaxial Si-Ge structures induced by ion beam bombardment has been studied using a He+ channeling technique. It is shown that hot ion beam bombardment (230°C, Si+ ions with energy 200 keV and fluence 6·1013 ion/cm2) of thin strained Si-Ge layers results in partial strain relaxation. A model of the strain relaxation induced by radiation damage
is proposed.
Study of Low-Energy Ion Assisted Epitaxy of Gan Films: Influence of the Initial Growth Rate
Authors: Gerlach J. W. , Schrupp D. , Schwertberger R. , Rauschenbach B. , Anders A. 
Published: April 2011

AbstractThe deposition of thin epitaxial hexagonal gallium nitride films on c-plane sapphire by low-energy nitrogen ion assisted deposition is shown to result in films of high crystalline quality. The quality can be further heightened by using the concept of an isothermal growth rate ramp. Characterization of film structure, defect density distribution and surface topography by XRD, RBS/C, and AFM, respectively, reveals the importance of the nitrogen ion energy and the ion to atom ratio on the film properties.
Biaxially Textured Buffer Layers on Large-Area Polycrystalline Substrates
Authors: Dzick J. , Sievers S. , Hoffmann J. , Thiele K. , Garcia-Moreno F. , Usoskin A. , Jooss C. , Freyhardt H. C. 
Published: April 2011

AbstractBiaxially textured yttria stabilized zirconia (YSZ) buffer layers were deposited on long polycrystalline metallic tapes by an ion-beam-assisted deposition process (IBAD) to serve as templates for high-current carrying Y1Ba2Cu3O7-x (YBCO) films. YSZ was deposited by a dualionbeam equipment with two 11 cm Kaufman ion sources. The coating of large-area technical substrates, large in comparison with the ion sources, requires substrate movements to render YSZ films of homogeneous texture quality. These movements can hinder cooling of the metallic tapes in the absence of a thermal contact. Therefore, the temperature of those small-heat-capacity substrates could rise to above 100 °C within minutes, causing a decrease of the in-plane alignment of YSZ. The investigation of the temperature dependence of the IBAD process reveals that the best results of the in-plane alignment could be obtained by room temperature deposition. Applying high tape velocities hinder a rise of the deposition temperature to above 90 °C. Therefore, it is possible to deposit YSZ films on metal tapes (up to 60 mm × 1000 mm) with in-plane textures down to 15° full width at half maximum (FWHM), which allow their coating with highcurrent-carrying YBCO films.
Microstructural Evolution of Ion Bombarded Copper Thin Films
Authors: Wagner T. , Müller D. 
Published: April 2011

AbstractThe effect of low-energy ion bombardment on the microstructure of copper films will be described. The copper films have been deposited on SiNx-coated, oxidized Si wafers by magnetron sputtering with a simultaneous bombardment of low-energy argon ions (60 eV). The films were annealed at 450°C in HV. The ion bombardment leads to a stronger and sharper {111} texture of the as-deposited films. After annealing, the ion-bombarded films had a significantly smaller grain size than films produced without ion bombardment. The experimental results will be discussed relating the textures of the as-deposited films with the grain sizes obtained after annealing. Details will be given describing how the microstructure of Cu films can be tailored using low-energy argon ion bombardment.
Electron Channeling X-ray Microanalysis for Cation Configuration in Irradiated Magnesium Aluminate Spinel
Authors: Matsumura S. , Soeda T. , Zaluzec N. J. , Kinoshita C. 
Published: April 2011

AbstractHigh angular resolution electron channeling x-ray spectroscopy (HARECXS) was examined as a practical tool to locate lattice-ions in spinel crystals. The orientation dependent intensity distribution of emitted x-rays obtained by HARECXS is so sensitive to lattice-ion configuration in the illuminated areas that the occupation probabilities on specific positions in the crystal lattice can be determined accurately through comparison with the theoretical rocking curves. HARECXS measurements have revealed partially disordered cation arrangement in MgO·nAl2O3withn= 1.0 and 2.4. Most A13+lattice-ions occupy the octahedral (VI) sites with 6-fold coordination, while Mg2+lattice-ions reside on both the tetrahedral (IV) and the octahedral (VI) sites. The structural vacancies are enriched in the IV-sites. Further evacuation of cations from the IV-sites to the VI-sites is recognized in a disordering process induced by irradiation with 1 MeV Ne+ ions up to 8.9 dpa at 870 K.
Theoretical Explanation of Pt Trimers Observed by Z-Contrast STEM
Authors: Sohlberg Karl , Pantelides Sokrates T. , Pennycook Stephen J. 
Published: April 2011

AbstractFirst-principles quantum-mechanical calculations on γ-alumina have revealed a fascinating “reactive sponge” phenomenon. γ-alumina can store and release water, but in a unique, “reactive” way. This “reactive sponge process” facilitates the creation of aluminum and oxygen vacancies in the alumina surface. Earlier atomic-resolution Z-contrast STEM images of ultradispersed Pt atoms on a γ-alumina support showed the individual atoms to form dimers and trimers with preferred spacings and orientations that are apparently dictated by the underlying support[1]. In turn, the reactive sponge property of γ-alumina is the key to understanding the Pt clusters. Our calculations demonstrate that if three Pt atoms fill three vacancies created during the reactive sponge process, the resulting geometry precisely matches that of the Pt trimers observed in the Z-STEM images. Understanding the initial nucleation of small clusters on the complex gamma alumina surface is an essential first step in determining the origins of catalytic activity.
Quantitative Mapping of Concentrations and Bonding States by Energy Filtering TEM
Authors: Mayer J. , Plitzko J. M. 
Published: April 2011

AbstractWe have developed new methods to quantify the data acquired by electron spectroscopic imaging (ESI) in an energy filtering TEM. The analysis is based on recording series of energy filtered images across inner-shell loss edges or in the low-loss region. From the series of ESI images, electron energy loss (EEL) spectra can be extracted and subsequently analysed using standard EELS quantification techniques. From an ESI series one can measure the absolute amount (area density) of an element in the given sample area or the concentration ratios of one element with respect to other elements. Spectrum line-profiling has been shown to be an efficient way to acquire and present the information on the chemistry of an interface. The results obtained for different metallisation layer systems show that segregation in the monolayer range can still be analysed with high spatial resolution. For the study of the energy-loss near-edge structure (ELNES) a higher energy resolution is required. ESI series with narrow energy window width can be used to distinguish between different bonding states of a given element and is demonstrated for thin films of diamond and amorphous carbon.
Measuring the Thin Film Strain Tensor Near Aluminum Grain Boundaries via a New Image Processing Approach to CBED HOLZ Patterns
Authors: Inoue J. , Schwartzman A. F. , Freund L. B. 
Published: April 2011

AbstractHOLZ lines formed in a CBED pattern provide the most accurate means to measure a local strain tensor with high spatial resolution over mesoscopic length scales. With the advent of energy-filtering in a field-emission TEM, the precision of this measurement increases by filtering out the inelastically scattered electrons. This paper presents an alternate approach to obtaining the same increased precision by image processing of CBED patterns formed in a conventional LaB6 microscope. This technique results in the determination of the full strain tensor within ±0.01%. It is based on developing a Wiener filter for CBED patterns, deconvoluting the point spread function of the CCD camera, using the Hough transform to measure distances between HOLZ line intersections, and subtracting out an experimentally determined projector lens distortion. The present technique has been used to measure the strain tensor for the two types of grain boundaries found in MBE grown Al thin films on Si which have the mazed bicrystal microstructure.
Inelastic Deformations in Multi-Walled Carbon Nanotubes
Authors: Tekleab D. , Czerw R. , Rubio A. , Ajayan P.M. , Carroll D.L. 
Published: April 2011

ABSTRACTWe report the use of high power ultrasonic agitation to create inelastic deformations in multiwalled carbon nanotubes. Using STM coupled with TEM we show that this damage can range from kinking to breaking of continuous tube walls into segments. Such deformed tubes provide an insight into the role of re-hybridization in the electrical and mechanical properties of tubes.
Effect of Gas Adsorption on the Electrical Properties of Single-Walled Carbon Nanotubes Mats
Authors: Marliere C. , Poncharal P. , Vaccarini L. , Zahab A. 
Published: April 2011

ABSTRACTSingle wall nanotubes have been made by arc-discharge method. Residual impurities (fullerenes, amorphous carbon, catalyst metals…) have been removed by tangential filtration process followed by high temperature annealing under vacuum (1200 °C). In this work we present results on the influence of the surrounding gas nature (N2, H2, CO2, H2O…) on the electrical resistivity of carefully outgassed mat of such samples.In particular, we have observed that the sample resistance exhibits a strong dependence on water contamination during the transfer to the measurement reactor.
Fluorinated Diamond-Like Carbon Films Produced by Plasma Immersion Ion Processing Technique
Authors: Hakovirta M. , Lee D. H. , He X. M. , Nastasi M. 
Published: April 2011

ABSTRACTFluorinated diamond-like carbon (F-DLC) coatings were deposited on polished silicon substrates with plasma immersion ion processing (PIIP) technique. In the PIIP technique, pulsed glow discharge plasma from a mixture of acetylane and hexafluoroethane gases was used. Contact angle measurements were performed in order to see the un-wetting properties of the coatings. The film composition was measured with Rutherford Backscattering Spectroscopy (RBS) and Elastic Recoil Detection Analysis (ERDA) and the hardness was measured with a Nanoindenter® II. The results clearly show that the un-wetting properties and hardness are strongly dependent on the fluorine incorporation in the F-DLC coatings. With optimized gas ratio of acetylane and hexafluoroethane gases, a combination of extremely good un-wetting properties and high hardness was achieved.
Voids Investigation of Amorphous Carbon Films Deposited by DC-Magnetron Sputtering: A Small Angle x-ray Scattering and Gas Thermal Effusion Study
Authors: Freire F.L. , Jacobsohn L.G. , Franceschini D.F. , Camargo S.S. 
Published: April 2011

ABSTRACTAmorphous carbon films were deposited onto (100) Si crystals and onto ultra-pure Al foils by dc-magnetron sputtering with different Ar plasma pressures, from 0.17 to 1.4 Pa. We investigate the voids structure and the voids density in these films by means of small angle x-ray scattering (SAXS) and mass spectrometry of effused gases. The analysis of the effusion spectra provided clear evidence that films deposited at lower pressures are compact, while the films deposited at higher pressure present a more open structural arrangement, confirming density results obtained by using ion beam techniques. SAXS results reveal that the fraction of open volumes increases with the plasma pressure: a direct correlation between film density and open volume fraction is found. These different film microstructures could be explained by the existence of different bombarding regimes during film growth
Effects of Composition on the Microstructures and Optical Properties of Hydrogenated Amorphous Silicon Carbide Films Prepared by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition
Authors: Chan Lih-Hsiung , Chou Wei-Zen , Chou Lih-Hsin 
Published: April 2011

ABSTRACTHydrogenated amorphous silicon carbide films (a -SiC:H) were prepared from CH4, SiH4, and Ar mixtures by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition (ECR PCVD). The deposition of the thin films was proceeded with the following optimized conditions; microwave power: 900W, Ar flux : 90sccm, and total flux: 113.4 sccm. The substrate temperature was around 100∼120°C during deposition. For comparisons, the relative flux ratio of methane to silane was varied to produce thin films of different compositions to investigate the relationships between the associated compositions of films and their corresponding microstructures and optical properties. Moreover, both film's microstructures and their optical properties were analyzed to find out as to how they are interrelated. Furthermore, the surface morphology and amorphous microstructures were confirmed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), respectively. And, x-ray Photoelectron Spectroscopy (XPS) was employed to study the relative atomic ratio of C to Si along with the bonding conditions in the thin films. Finally, the Hydrogen concentration and the amounts of C-H and Si-H bonds were determined by Fourier transform infrared spectroscopy(FTIR), while the optical properties were measured by optical spectrophotometer.
Enzymatic Template Synthesis of Polyphenol
Authors: Bruno Ferdinando F. , Nagarajan Ramaswamy , Sidhartha Jena S. , Yang Ke , Kumar Jayant , Tripathy Sukant , Samuelson Lynne 
Published: April 2011

AbstractAn alternative, biocatalytic approach for the synthesis of a new class of water soluble and processable polyphenols is presented. In this approach, the enzyme horseradish peroxidase (HRP) is used to polymerize phenol in the presence of an ionic template. The template serves as a surfactant that can both emulsify the phenol monomer and growing polyphenol chains and provide water solubility of the final polyphenol/template complex. This approach is a simple, one step synthesis where the reaction conditions are remarkably mild and environmentally compatible. The final product is a water soluble, high molecular weight complex of polyphenol and the template used. The approach is also very versatile as numerous templates may be used to build in specific functionalities to the final polyphenol complex. Polystyrene sulfonates (SPS), lignin sulfonate and dodecyl benzene sulfonates (micelles) are the templates investigated in this study. Thermal analysis and UV-Vis spectroscopy shows that these complexes have exceptional thermal stability and a high degree of backbone conjugation. Electrical conductivities on the order of 10−5 S/cm and third order nonlinear optical susceptibilities (χ(3)) of 10−12 esu are also observed. In the case of the SPS template, under certain conditions, a sol gel complex may be formed. This enzymatic approach offers interesting opportunities in the synthesis and functionalization of a new class of processable polyphenolic materials.
Electroactive Nonionic Polymer Gel-Swift Bending and Crawling Motion
Authors: Hirai T. , Zheng J. , Watanabe M. , Shirai H. , Yamaguchi M. 
Published: April 2011

AbstractWe have found a nonionic polymer gel swollen with nonionic dielectric solvent can be actuated by applying an electric field. The motion was not only far much faster than conventional polyelectrolyte gel materials, but also far much bigger in deformation. The motion was completed, for instance, within 60 ms and the deformation reached over 100%. The heat loss is negligible compared to that of polyelectrolyte gels. The deformation is not only bending, but also crawling. The principle was suggested to be charge-injected solvent dragging in the gel. The force was suggested to be proportional to the square of the electric field and proportional to the dielectric constant of the solvent. The principle was suggested to be promising and applicable to other conventional polymers.
The Voltage and Composition Dependence of Switching in a Polymer Current Limiter Device
Authors: Duggal Anil R. 
Published: April 2011

AbstractThe high power electrical switching properties of a polymer current limiter device are studied as a function of applied voltage. It is shown that a dramatic change in switching behavior occurs at a characteristic voltage. Below this voltage, the device switches to a high resistance state whereas at higher applied voltages it does not. It is shown that the high voltage, low resistance state has similar electrical characteristics to an arc discharge. Material variation experiments are also described which demonstrate that the changeover depends sensitively on the contact resistance between the filler particles of the composite material.
Electro-Mechanical Properties of Electron Irradiated P(VDF-TrFE) Copolymers Under Different Mechanical Stresses
Authors: Cheng Z.-Y. , Gross S. J. , Bharti V. , Xu T.-B. , Mai T. , Zhang Q. M. 
Published: April 2011

AbstractThe electro-mechanical properties of high energy electron irradiated poly(vineylidene fluoride-trifluorethylene) (P(VF-TrFE)) copolymers under different mechanical stress conditions are reported. In stress free condition, the electric field induced longitudinal and transverse strains of the irradiated P(VDF-TrFE) copolymer films at room temperature (RT) can reach about 5% and more than 3% respectively. The longitudinal strain response of the material under hydrostatic a pressure up to 83 atmospheses was studied at RT. The transverse strain response of the material at RT was studied under uniaxial tensile stress. It was found that the material has a high load capability and for stretched films along the stretching direction the induced strain remains high, even at about 45 MPa. The temperature dependence of the strain response is also characterized. Both the temperature and stress dependence of the strain response indicate that the electric field induced strain response originates from the electric field induced local phase transition.
Ceramics Superplasticity
Authors: Wakai Fumihiro 
Published: April 2011

AbstractThe international joint project “Ceramics Superplasticity” has been conducted from 1995 till 1999 by a cooperation between the Japan Science and Technology Corporation (JST) and Max-Planck-lnstitute for Metals Research (MPI-MF). The new type of covalent ceramics was developed through atomic level processing, and novel properties such as superplasticity were investigated. The development of local analysis technique of disordered structure combined the two research fields, grain boundary of crystalline solids and structure of amorphous.
The Industrial Application of Aluminum Superplastic Forming
Authors: Barnes A. J. 
Published: April 2011

AbstractOver the past thirty years superplastic aluminum forming has advanced from a laboratory curiosity to a well established manufacturing route. Applications are now found in many and diverse markets, including: medical systems, specialist automobiles, rail cars, architectural panels and all types of aircraft.This paper examines the reasons for success in these markets and explores future prospects including the potential for fast forming alloys currently under development.
Materials Design and Processings for Industrial High-Strain Rate Superplastic Forming
Authors: Hosokawa H. , Higashi K. 
Published: April 2011

AbstractThe optimum materials design in microstructural control could be developed for the highstrain-rate superplastic materials in the industrial scale. In the present work, it is reported that the high-performance-engine pistons with near-net-shape can be fabricated by the superplastic forging technology in the high-strain-rate superplastic PM Al-Si based alloy, which is produced by using this optimum materials design.
Influence of Equal-Channel Angular Pressing on the Superplastic Properties of Commercial Aluminum Alloys
Authors: Lee Sungwon , Langdon Terence G. 
Published: April 2011

AbstractEqual-channel angular (ECA) pressing was used to refine the microstructure in two commercial aluminum alloys, Al-2024 and the Supral-100 Al-2004 alloy. The ECA pressing was conducted at room temperature and at elevated temperatures for both alloys using several different processing routes. Tensile testing was carried out at elevated temperatures on both pressed and unpressed samples of each alloy in order to evaluate the effect of the pressing. This paper describes the influence of the ECA pressing on the subsequent mechanical properties of these two alloys. For both alloys, it is shown that the optimum superplastic conditions are influenced by the ECA pressing, and in practice there tends to be a decrease in the optimum temperature for superplasticity and a corresponding increase in the optimum strain rate. In addition, there was evidence for high strain rate superplasticity (HSR SP) in both alloys after the ECA pressing procedure.
Superplastic Deformation Behavior of Zn-Al Alloys
Authors: Ha Tae Kwon , Koo Hyun Woo , Eom Tae Shin , Chang Young Won 
Published: April 2011

AbstractThe superplastic deformation behavior of a quasi-single phase Zn-0.3 wt.% Al and a microduplex Zn-22 wt.% Al eutectoid alloy has been investigated in this study within the framework of the internal variable theory of structural superplasticity (SSP). Load relaxation and tensile tests were conducted at room temperature for quasi-single phase alloy and at 200°C for eutectoid alloy. The flow curves obtained from load relaxation tests on superplastic Zn-Al alloys were shown to consist of the contributions from interface sliding (IS) and the accommodating plastic deformation due to dislocation activities. The IS behavior could be described as a viscous flow characterized by the power index value of Mg = 0.5. In the case of quasi-single phase Zn-0.3 wt.% Al alloy with the average grain size of 1 µm, a large elongation of about 1400 % was obtained at room temperature. In a relatively large-grained (10 µm) single-phase alloy, however, grain boundary sliding (GBS) was not expected from the analysis based on the internal variable theory of SSP.