bluuebunny/crossref_metadata_2025_split huggingface dataset:
Double Quantum Wire Magnetic Response
Authors: Smirnov Anatoly Yu. , Mourokh Lev G. , Horing Norman J.M. 
Published: April 2011

ABSTRACTThe induced magnetic moment of a biased semiconductor tunnel-coupled parallel double quantum wire system is examined here. The wires are in a series arrangement with tunnel coupling to each other and to leads. Their parallel lengths and associated continuous spectrum are taken in the direction perpendicular to the lead-to-lead current. The equations of motion for the double-wire electron Green's function are formulated and analyzed using the transfer-tunneling Hamiltonian formalism. We determine the average magnetic moment of the double-wire system induced by a magnetic field applied perpendicular to the plane of the structure and we show that there are crossovers between diamagnetic and paramagnetic behavior, depending on the bias voltage, equilibrium chemical potential of the leads and temperature.
‥Recent Progress in Ferroelectic-gate FETs
Authors: Ishiwara Hiroshi , Park Byung-Eun 
Published: April 2011

ABSTRACTRecent progress in the research of ferroelectric-gate FETs is reviewed mainly from a view-point of the data retention characteristics. First, importance of insulator-inserted gate structures such as an MFIS (M; metal, F; ferroelectric, I; insulator, S; semiconductor) or MFMIS structure is described and the necessary conditions for the insulating buffer layer and the ferroelectric film are discussed. Then, experimental results for the SiO2 and high-k dielectric buffer layers combined with such ferroelectric films as SBT (SrBi2Ta 2O9) and BLT ((Bi,La)4Ti3O12) are presented, in which particular attention is paid to the discussion on the induced charge matching between the buffer layer and the ferroelectric film. As an example, it is shown in a Pt/BLT/LaAlO3/Si diode that the high and low capacitance values written by positive and negative pulses can be retained at least for 3 days. Finally, recent experimental results on the data retention characteristics of the ferroelectric-gate FETs are presented.
Photo-Induced Insulator-Semiconductor Transition in 12CaO·7Al2O3 (C12A7)
Authors: Hayashi Katsuro , Matsuishi Satoru , Kamiya Toshio , Hirano Masahiro , Hosono Hideo 
Published: April 2011

ABSTRACTWe report the first electronic conduction in main group metal oxides (MGOs) or light-metal oxides, which are represented by alkaline-earth oxides, alumina, and silica. They are believed to be never converted to an electronic conductor. One of the MGOs, 12CaO·7Al2O3 (C12A7), has optical transparency, but electrical insulation limits intrinsic form. It is characterized by sub-nanometer sized cages in the lattice framework. Hydride ion, H- was incorporated into the cage by a thermal treatment of C12A7 single crystals or ceramics in hydrogen atmosphere. The product, C12A7:H, was colorless, transparent and a good insulator having electronic conductivity less than 10-10 S·cm-1. We found that the C12A7:H exhibits a coloration of yellowish green corresponding to optical absorptions at 2.8 and 0.4 eV with simultaneous conversion into an electronic conductor with 0.3 S·cm-1 at 300 K upon a irradiation of ultraviolet light. The conductive state continued even after the irradiation was stopped. Inversion to the insulator occurred when heated more than ∼320°C accompanying with rapid decay of the optical absorptions. When temperature rose above 550°C, H2 gas was released from the sample and the photosensitivity was lost. We consider that high concentration of F+-like centers are created by photo-released electrons from the H- anions being captured by empty cages. Further, a migration of the electrons at the F+-like centers may be responsible for the conduction. The visible light absorption loss is estimated to be only 1% for a 200 nm thick conductive C12A7:H films. The present properties provides novel applications such as direct optical writing of conducting wires on insulating transparent media.
Ferroelectric Field Effect Device
Authors: Schrott A. G. , Misewich J. A. , Ramesh R. , Nagarajan V. 
Published: April 2011

ABSTRACTA ferroelectric field effect transistor with an oxide channel layer and a lead zirconate titanate gate oxide has been fabricated. The channel is a strontium ruthenate/titanate solid solution with n type semiconducting behavior, which has sufficient OFF-state free carrier concentration to provide proper balancing charge for ferroelectric stability. The dependence of channel resistance with gate voltage at room temperature yields a hysteresis curve with two state at zero volts with a ΔR/R of 75% and a coercive voltage of 3 volts. The device was subjected to more than 1010 cycles with no degradation and was also operated at 60° C with a only a slight reduction in the switching ratio.
Growth and Characteristics of Single Crystals of Lithium Niobate
Authors: Batra A. K. , Gebre T. , Stephens J. , Aggarwal M. D. , Lal R. B. 
Published: April 2011

ABSTRACTLithium niobate single crystal is an excellent material for various optical applications such as frequency conversion, optical switches, optical modulators and others. An automatic diameter control Czochralski crystals growth system has been designed and fabricated. A brief description of the entire system along with software developed has been described. With optimized growth parameters, pure and Fe/Mn doped crystals have been successfully grown using this system. Preliminary characterizations of these crystals have also been presented.
Engineering ZnO/GaN Interfaces for Tunneling Ohmic Contacts to GaN
Authors: Kaminska E. , Piotrowska A. , Golaszewska K. , Kruszka R. , Kuchuk A. , Szade J. , Winiarski A. , Barcz A. , Jasinski J. , Liliental-Weber Z. 
Published: April 2011

ABSTRACTWe have investigated two approaches for the fabrication of thin ZnO films: sputter deposition from the ZnO target and thermal oxidation of vacuum deposited Zn. The microstructure and electronic properties after consecutive steps of the formation of n-ZnO/p-GaN contacts have been studied using electron transmission microscopy and x-ray photoelectron spectrometry. We have achieved ohmic contacts by Zn oxidation and explain their ohmic behaviour in terms of a tunnel n+-ZnO - p-GaN junction.
Texture Evolution During Crystallization Of Thin Amorphous Films
Authors: Liu Q.K.K. , Schumacher G. 
Published: April 2011

ABSTRACTStress and energy distributions for crystallization of a thin amorphous film are calculated by means of 3D finite element method. The changes in energy are caused by elastic strain induced by different thermal expansion of the film and the substrate and by different mass densities of the crystal and the surrounding amorphous matrix. The calculations were performed for cubic crystal structure and for disc shaped crystals. Three crystal orientations (001), (011) and (111) were considered. Based on strain energy considerations the (001) orientation of crystals with respect to the film plane is energetically more favorable than (011) and (111) orientations. Interfacial and surface energies are certain to play a part in these effects as well.
Mo-Si Interface Formation by Ion Beam Sputter Deposition
Authors: Köhler A. , Gerlach J.W. , Höche T. , Chassé T. , Neumann H. , Frank W. , Wagner G. , Rauschenbach B. 
Published: April 2011

ABSTRACTMolybdenum-silicon (Mo-Si) multilayers for EUV lithography were prepared by ion beam sputter deposition at room temperature. The multilayer structure was determined by X-ray-diffraction and transmission electron microscopy. Textured molybdenum layers with preferential (110) orientation normal to the surface are observed. At the interfaces of all Mo-Si and Si-Mo pairs additional intermixing resulting in molybdenum silicide layers were noticed. These layers have a thickness of about 0.7 and 1.5 nm each, respectively. Due to this intermixing, the nominal thickness of the Mo and Si layers is reduced. The optical index contrast at the interface is also expected to decrease. This is in accordance with the obtained EUV reflectivity results of 64–65% at 13.4 nm which remains below the theoretical value of 74%. The formation of the silicide interface layers is discussed and an optimized deposition process focused on narrowing these transition layers is suggested.
Improvement of surface roughness by ultra-thin film deposition with oxygen cluster ion beam assist deposition
Authors: Toyoda Noriaki , Yamada Isao 
Published: April 2011

ABSTRACTTa2O5 films were deposited on a rough surface (average roughness 1.3nm, peak-to-valley 14nm) and surface roughness evolutions and improvements by O2 gas cluster ion beam (O2-GCIB) assisted deposition was studied. The average roughness dramatically decreased from 1.3nm to 0.5nm after deposition of Ta2O5 films 20nm in thickness with 7 keV of O2 cluster ion beams. As there was no etching or sputtering of Ta2O5 film by 7keV O2-GCIB irradiations, O2-GCIB assist deposition realized significant improvement of surface roughness by additional deposition of Ta2O5 film whose thickness was close to the peak-to-valley of original surface. It is expected that morphological evolution of the film by GCIB assist deposition becomes completely different from conventional ion assist deposition due to energetic cluster ion impacts.
Diamond Synthesis From Acetone Vapor And Impurity Control
Authors: Gyoda Kaoru , Tanaka Yuki , Takagi Yoshiki 
Published: April 2011

ABSTRACTWe synthesized diamond via gaseous phase of vaporized acetone. Molecular acetone decomposes to two methyl radicals with thermal activation. We propose here a new method for diamond synthesis with these methyl radicals from molecular acetone. With this method, we successfully synthesized diamond particles on Si substrates with shorter experimental time and lower energy consumption than conventional methods. With liquid carbon sources, such as acetone, impurity elements will be easily substituted in synthesized diamond thin film, which has wide applications for the future electronic devices. Nickel, Boron and Phosphorus doping results will be presented.
Properties of Titanium Oxide Thin Film Prepared with E-beam Evaporation
Authors: Hou Ping , Sun Lianchao 
Published: April 2011

ABSTRACTThe optical and mechanical properties of TiO2 film prepared by ion-assisted e-beam evaporation have been examined in this research. Spectroscopic ellipsometry analysis revealed an inhomogeneous behavior in both optical property and growth structure, vertically from substrate to the top surface of the film. This phenomenon was further confirmed with the electron microscopic analyses. The effects of deposition rate, chamber pressure, anode voltage and current on the stress of TiO2 films were also investigated and reported. Further study showed that a structural homogeneous film could be obtained through TiO2-SiO2 co-evaporation.
Study of Pore Architecture in Silicon Oxide Thin Films by Variable-energy Positron Annihilation Spectroscopy
Authors: Ito Kenji , Kobayashi Yoshinori , Yu Runsheng , Hirata Kouichi , Togashi Hisashi , Suzuki Ryoichi , Ohdaira Toshiyuki , Egami M. , Arao H. , Sakurai C. , Nakashima A. , Komatsu M. 
Published: April 2011

ABSTRACTApplication of porous silicon oxide thin films to nanotechnology is under intensive investigation. Introducing a large amount of nano pores into a silicon oxide matrix is important to develop low-k dielectrics for future ultra-large-scale integrated circuits (ULSI). In this work, we applied variable-energy positron annihilation to the characterization of porous silicon oxide thin films fabricated on silicon wafers by sputtering and spincoating. It was found that the sputtered film has higher open pore connectivity than that of the spincoated low-k film.
Surface Electrical Measurements of Photo-catalysis on Rutile TiO2(11O)
Authors: Kaisei Kiyohiro , Ishida Kenji , Horiuchi Toshihisa , Matsushige Kazumi 
Published: April 2011

ABSTRACTWe have studied the electronic properties of single crystal rutile TiO2(110) with surface electrical techniques; impedance spectroscopy and high sensitivity DC measurements. In the impedance spectroscopy we observed a spectrum involved in the dissociation of pure water on the TiO2 surface under UV irradiation. In the high sensitivity DC measurements we observed oscillations of the surface photo-current with three different long periodicities, which might have originated from the oxidation and reduction processes of water on TiO2 via photo-catalytic reactions induced by UV irradiation.
TEM Investigation of the Core/Cladding Interface of La2O3-Al2O3-SiO2 Glasses for High Power Fiber Lasers
Authors: Cheng Shang-Cong , Dejneka Matthew J. 
Published: April 2011

ABSTRACTFor fabricating Yb3+ doped La2O3-Al2O3-SiO2 glasses for high-powered fiber lasers, it is critical to choose the right core glass composition to obtain a high numerical aperture and to avoid phase separation. TEM techniques were used to study the relationship between the core composition and phase separation. In the study, inter-diffusion between the core and cladding glasses was found. The inter-diffusion caused large density fluctuation in the region of the core/cladding interface in fibers containing relatively high concentrations of La2O3. The TEM results were used to optimize the chemical composition of the core glass for high-power fiber lasers.
Study of The Quasicrystal Formation in Zr46.8Ti8.2Cu7.5Ni10Be27.5 Bulk Metallic Glass
Authors: Soubeyroux J.L. , Pelletier J.M. , Van de Moortèle B. , Epicier T. 
Published: April 2011

ABSTRACTThe formation of the primary crystals appearing during isothermal annealing of the Zr46.8Ti8.2Cu7.5Ni10Be27.5 (Vit4) bulk metallic glasses has been studied by in-situ neutron diffraction, DSC, high resolution TEM and electron diffraction. We have evidenced that the primary phase appearing on the isothermal plateau at 620 K is quasicrystalline and is beryllium free. Moreover, we have prepared an alloy with the composition determined by EDX (without beryllium), and studied the formation of quasicrystals in this alloy. A comparison is done between the quasicrystalline phases appearing during the annealing of Vit4 and the quasicrystals prepared without beryllium in an amorphous alloy prepared by melt spinning. In particular they have the same intensities and peak positions in the diffraction studies.
Characterization of the Structure of a Novel Refractory Alloy Glass – Ni60Nb37Sn3
Authors: Tokarz Michelle L. , Daniels Matt , Bilello John C. , Rek Zofia 
Published: April 2011

ABSTRACTBulk forms of Refractory Alloy Glasses (RAGs) of the composition Ni60Nb37Sn3 have recently been synthesized as part of a larger project for potential use in structural applications. Modeling efforts of such metallic glasses have traditionally involved the use of hard sphere models without regard to potential electron density fluctuations of individual components. X-ray characterization of these materials (in both reflection and transmission modes) provided scattering data necessary for subsequent radial distribution analysis, which gives structural information such as nearest neighbor distances and packing characteristics. A model radial distribution function (RDF) was constructed based upon a hard sphere space filling assumption and compared to the RDFs obtained from experimental scattering data. The experimental RDFs showed no difference from the model RDF within the limit of experimental error, with regard to nearest neighbor distances and coordination numbers of the first two nearest neighbors.Additionally, transmission mode scattering experiments from a white beam x-ray source (E = 2 to 40 keV) demonstrated a through thickness amorphous structure of 2mm thick samples. Converted line profiles from the two-dimensional diffraction patterns from this experiment also showed agreement with reflection mode experiments. Samples of Vitreloy-106 (Zr57Nb5Cu15.4Ni12.6Al10) of similar thicknesses were used as standards due to the well-known behavior of this particular class of metallic glasses.
Effect of Loading Rate on Failure in Bulk Metallic Glasses
Authors: Jiao T. , Fan C. , Kecskes L.J. , Hufnagel T.C. , Ramesh K.T. 
Published: April 2011

ABSTRACTWe have investigated failure in bulk metallic glass-forming alloys under dynamic compression. We implemented a recovery technique for the compression Kolsky bar to obtain dynamically deformed, intact specimens at various stages of deformation; this allows us to characterize the development of failure. We have also used high-speed photography to examine the failure process during the recovery experiments. The experimental results indicate that the failure under dynamic loading is somewhat different from that under quasi-static loading. Specimens subjected to quasistatic deformation developed multiple shear bands and substantial plastic deformations, while specimens subjected to dynamic (—strain rate ∼103 s-1) compressive loading fail by fracture along one dominant shear band. The mechanisms of dynamic failure in bulk metallic glasses are discussed on the basis of these experimental results.
Obsevations Ofstress-Induced Structuraldisorder and Fictive Stress in Bulk Metallic Glasses
Authors: Chen Ho-Sou , Kato Hidemi , Inoue Akihisa 
Published: April 2011

ABSTRACTThe transformation from Newtonian to non-Newtonian viscous flow at the glass transition of Pd- and Zr-based alloy glasses has been investigated in compressive tests under either a constant strain rate, or a constant load. The transition occurs at a critical stress being nearly independent of temperature. The mechanism of the transition thus has been attributed to the stress-induced structural relaxation. This paper describes the evidence of stress-induced disorder as indicated by the change in the viscosity with stress and the evolution of specific heat of the alloy glasses subjected to non-Newtonian steady-state viscous flow. Also presented in this paper is the in-situ observation of structural disorder, by direct measurements of the temperature change of sample, in particular the soften process during a constant load deformation. The heat of evolution is then calculated, and found to scale as the logarithm of the normalized viscosity during entire deformation. This result implies that the relationship between the structural disorder, as indicated by the enthalpy change and viscosity is the same in the transient state during deformation as well as in the steady-state flow process. This is conceptionally very important in that it enables us to introduce a fictive stress which indirectly represents the glass structure.
High Temperature Deformation in the Amorphous or Partially Crystallized Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass
Authors: Wang Q. , Blandin J.J. , Suery M. , Pelletier J.M. 
Published: April 2011

ABSTRACTThe high temperature deformation of the Zr41.2Ti12.5Cu13.8Ni10Be22.5 bulk metallic glass (BMG) is studied in the supercooled liquid region. Both fully amorphous and partially crystallized states are investigated. In the studied experimental domain, the amorphous alloy exhibits a Newtonian behavior at high temperature and/or low strain rate whereas a transition to non-Newtonian behavior is observed when the temperature is decreased and/or the strain rate is increased. In the Newtonian domain, the dependency of the viscosity upon temperature can be described by an Arrhénius law. As far as the as-received alloy is maintained at high temperature for which phase separation and primary crystallisation is expected, the flow stress continuously increases, which is at least partly attributed to a change in the residual amorphous phase.
Yucca Mountain Project Status
Authors: Kiess Thomas E. , Hanauer Stephen H. 
Published: April 2011

ABSTRACTThe Yucca Mountain site was designated in July 2002 as the United States' location for a geological repository for spent nuclear fuel and other high-level radioactive wastes. This site designation was a watershed event in the history of the project, enabling the U.S. Department of Energy to seek a license from the U.S. Nuclear Regulatory Commission to construct and operate a geologic repository. Summarized below are the history and technical basis for this site designation and some key anticipated future events. Many of the significant events to date have been framed by the Nuclear Waste Policy Act (and Amendments) and the requirements of the regulatory standard.
Modelling the Sorption of Actinides onto Cement: An Approach with the Surface Co-Precipitation Model
Authors: Sugiyama Daisuke , Fujita Tomonari 
Published: April 2011

ABSTRACTAn approach, assuming that co-precipitation on the surface of the cement phase dominates ‘sorption’, is proposed and discussed to interpret the sorption behaviour of the cement-complex system. This model takes account of the mineralogical composition of Ordinary Portland Cement (OPC) and assumes that Calcium Silicate Hydrates (C-S-H) dominates the sorption (fixation) of actinide onto OPC and that a small amount of surface co-precipitation of actinides with calcium hydroxide in the structure of C-S-H is formed during the late period of the fixation process. Therefore, this will be referred to as the ‘Surface Co-Precipitation Model (SCPM)’. The modelling results show generally good agreement between the predicted and measured distribution ratios of plutonium, thorium and neptunium, of which the dominant species in high pH solution are neutral species, on OPC.
Phases Formation Rate at Synthesis of Actinide Waste Forms
Authors: Laverov N. P. , Yudintsev S. V. , Lapina M. I. , Stefanovsky S. V. , Chae S. C. , Ewing R. C. 
Published: April 2011

ABSTRACTRate of zirconolite (CaZrTi2O7) and pyrochlores (Gd2Ti2O7, CaCeTi2O7, and Gd2Zr2O7) formation by cold pressing and sintering (CPS) was studied. Batches were prepared from CaCO3, ZrO2, TiO2, CeO2, and Gd2O3 milled to size of 20–30 micrometers. Powders were compacted and sintered in air (oxygen) at 800–1600 °C for 0.5–55 hours. Samples were examined with XRD, SEM, and TEM. Phase formation rate was the fastest in Gd-Ti-O and Ca-Ce-Ti-O systems and the reactions were the slowest in Gd-Zr-O system. In zirconolite-based system reaction rate had intermediate value. For three systems at 1400 C equilibrium was reached in 3–5 hours, while in Gd-Zr-O system required about ten time longer reaction time. High formation rate was evidently one of the reasons to select the pyrochlore (Ca,Gd,U,Pu)2(Hf,Ti)2 O7 as a host for Pu in the USA.We have also studied an effect of titanium on pyrochlore formation in the Gd-Zr-Ti-O system. The batches with nominal composition Gd2Ti0.4Zr1.6O7, Gd2Ti0.2Zr1.8O7, and Gd2Ti0.1Zr1.9O7 were compacted and annealed at 1500–1600 °C for 3–98 hours. In most of them along with pyrochlore non-reacted zirconium and gadolinium oxides were found. Their content reduced with temperature and sintering duration increasing. Pyrochlore composition was varied in different parts of the samples. Variation range decreased with rise of temperature, runs duration, and titanium content in the precursors. Partial substitution of Ti for Zr increased rate of pyrochlore formation. However, even at the highest titanium content (0.4 formula units) and temperature of synthesis (1600 °C) too long sintering duration in tens of hours is required to form a single-phase pyrochlore matrix. This makes their production from oxide precursor via CPS route inefficient. Inductive melting in a cold crucible or self-sustaining high-temperature synthesis are more promising methods for fabrication of the zirconate pyrochlores.