bluuebunny/crossref_metadata_2025 huggingface dataset:
Bi-Sr-Ca-Cu-O Superconducting Oxides Synthesized from Different Diffusion Couples
Authors: Tachikawa Kyoji , Watanabe Takayuki , Takayuki Inoue Takayuki Inoue , Kenji Shirasu Kenji Shirasu
Published: February 2005

Thick Bi-Sr-Ca-Cu-O(BSCCO) layers have been synthesized by a reaction diffusion between a Sr-base oxide substrate and a Bi-base oxide coating layer. Effects of the composition of diffusion couples on superconducting properties and structures of resulting reaction layers have been studied. The most favorable diffusion couple to form a uniform 2212 layer was 2001 (Bi2CuO4) and 0212(Sr2CaCu2O5). The Pb substitution for Bi in the coating layer produced a thick 2223 layer with no crystal orientation, unlike the 2212 reaction layer which showed a strong a-axis orientation. The Li substitution for Bi significantly enhanced the reaction diffusion, and an offsetTcof 83 K was obtained after a heat treatment at 800°C for 10 min. A study was also performed on the powder-diffusion process in which powders of a Sr-base oxide and a Bi-base oxide were mixed and sintered.
Preparation of Lateral Isolation Structures by Controlling Bi or Ca Compositions in Bi-System Superconducting Films
Authors: Usuki Tatsuro , Yasui Ichiro , Yorinobu Yoshisato Yorinobu Yoshisato , Shoichi Nakano Shoichi Nakano
Published: February 2005

Two kinds of monolithic lateral isolation structures have been obtained by controlling Bi or Ca compositions in the lateral direction using a Bi-oxide system for the first time. One is a BiSrCaCuO/SrCaCuO/BiSrCaCuO structure, which was made from a Bi-O/SrCaCuO layer. The other is a BiSrCaCuO/BiSrCuO/BiSrCaCuO structure, which was made from a Ca-F/BiSrCuO layer. Each BiSrCaCuO area is composed of a 2-2-1-2 phase and a 2-2-2-3 phase, with high crystallinity in the c-axis orientation. A SrCaCuO area indicates semi-insulation. The BiSrCuO area showed a flat temperature dependence of resistivity above 25 K and exhibited a resistivity of about 6 mΩ·cm.
Photo Chemical Vapor Deposition of Metal Oxide Films Relating to Bi-Sr-Ca-Cu-O Superconductor
Authors: Koinuma Hideomi , Chaudhary Kaliq A. , Nakabayashi Masaaki , Shiraishi Tadashi , Hashimoto Takuya , Kitazawa Koichi , Suemune Youichi , Yamamoto Takakazu
Published: February 2005

Oxide films relating to high-T
c superconducting Bi-Sr-Ca-Cu-O system were prepared by an oxidative photochemical vapor deposition using a low pressure mercury lamp. Bismuth oxide film was prepared by the photo decomposition of Bi(C6H5)3 in the presence of oxygen (20 Torr) at 300°C, while no film was obtained without the UV light irradiation. The UV light irradiation increased X-ray diffraction peak intensities of CuO, CaCO3, and SrCO3 films prepared from Cu(dipyvaloylmethanate: DPM)2, Ca(DPM)2, and Sr(DPM)2, respectively, at a temperatures of 400°C. By simultaneous supply of Ca(DPM)2 and Cu(DPM)2, Ca2CuO3 crystalline film without CaCO3 contamination was formed at 400°C. Without the UV irradiation, amorphous Ca-Cu-O film was obtained by thermal CVD. Photochemical reactions using N2O and NO2 instead of O2 were also examined.
Growth of Ge Microcrystals in SiO2 Thin Film Matrices: A Raman and Electron Microscopic Study
Authors: Fujii Minoru , Hayashi Shinji , Yamamoto Keiichi
Published: February 2005

The growth of Ge microcrystals in SiO2-Ge mixture films prepared by an rf co-sputtering method was studied by Raman spectroscopy and electron microscopy. It was found that in the as-deposited films, Ge clusters about 2 nm in diameter are embedded in SiO2 matrices and they are grown to Ge microcrystals by thermal annealing. It is shown that annealing at 800°C is necessary to prepare well-grown microcrystalline samples. The microcrystalline size dependence of the Raman spectrum was investigated. The increase in the linewidth observed with decreasing the size can be well explained by the phonon confinement theory, while the downward shift of the peak frequency predicted from the theory was not observed, presumably due to the stress caused by SiO2 matrices.
New Short-Pitch Bistable Ferroelectric (SBF) Liquid Crystal Displays
Authors: J. Fünfschilling J. Fünfschilling , M. Schadt M. Schadt
Published: February 2005

We present a new type of bistable electro-optical device based on ferroelectric S
c
* liquid crystals exhibiting a short pitch (0.43 µm) and a large spontaneous polarization (50···150 nC/cm2). Features of the new short pitch bistable ferroelectric liquid crystal displays (SBF-LCDs) which are based on the effect are: short switching times (25 µs) at room temperature using 2 µm cell gap and 30 V bipolar pulses; contrast ratios>35; multiplexing ratios>1000; large on-state brightness due to a large memory switching angle of 40° as well as a weak temperature dependence of both, response time and memory tilt angle.
Dynamic Orientation Structures of Layer-Tilted Surface-Stabilized Ferroelectric Liquid Crystal Cells
Authors: T. C. Chieu T. C. Chieu
Published: February 2005

The dynamic orientation structures of layer-tilted surface-stabilized ferroelectric liquid crystals (FLC) under applied field are analyzed with a non-uniform switching model based on a one-dimensional elastic-continuum free-energy theory in which the elastic-distortion, surface-interaction and electrostatic energies, constant electric-displacement and non-uniform permittivity are taken into account. The effect of alignment layers on the electrostatic potential is also included through appropriate boundary conditions. It is found that there exists a spatially varying depolarization field along the FLC layer, which tends to de-stabilize the bistability of the cell, and has intensity increasing monotonically with the spontaneous polarization density of the FLC medium, but decreasing with smaller thickness and higher conductivity of the alignment layers. Results of the director and electric field distributions along the cell, and the optical transmissions are presented for different material constants, surface-anchoring strengths and applied voltage conditions.
Anomalous Hydrodynamic Behaviors of Smectic Liquid Crystals at Low Frequencies
Authors: Jun Yamamoto Jun Yamamoto , Koji Okano Koji Okano
Published: February 2005

We report the details of the measurements of the layer compression modulus B and the longitudinal viscosity \tildeη of several thermotropic smectic phases in the frequency range from 10 Hz to 1 kHz. We confirmed for smectic phases having liquidlike layers (including smectic-A, smectic-C and chiral smectic-C phases) that \tildeη has an anomalous frequency (ω) dependence of the type \tildeκ/ω predicted theoretically by Mazenko, Ramaswamy and Toner, and also by Katz and Lebedev. The temperature dependence of B and the strength of the anomalous viscosity \tildeκ were measured in detail, which revealed, in particular, that a close correlation exists between \tildeκ and B. We also found that, under an applied magnetic field, which tends to suppress the thermal fluctuations of smectic layers, \tildeκ decreases whereas B increases, a result which is consistent with the premise of the advocated theories.
Structural Change of the IR-Transmitting Tellurite, Gallate and Aluminate Glasses Caused by the 60Co-Gamma Ray Irradiation
Authors: Nishida Tetsuaki , Yamada Miho , Tomoko Ichii Tomoko Ichii , Yoshimasa Takashima Yoshimasa Takashima
Published: February 2005

The 57Fe-Mössbauer parameters of γ-ray irradiated xK2O·(95-x)TeO2·5Fe2O3 (x=5, 25), xMgO·(95-x)TeO2·5Fe2O3 (x=5, 25) and 95TeO2·5Fe2O3 glasses suggest a cleavage of Te(Fe)-O-Te bond and an increase of the symmetry of Te(Fe)O4 trigonal bipyramids. There is a linear relationship between the resultant T
g and the quadrupole splitting (Δ), obeying the “T
g-Δ rule”. A cleavage of Ga(Fe)-O-Ga bond and an increased symmetry of Ga(Fe)O4 tetrahedra are found in the irradiated 50CaO·40Ga2O3·10Fe2O3 glass. The X-ray diffraction and FT-IR absorption spectra indicate the precipitation of Ga2O3 and CaO phases, and a marked decrease of transmittance is observed in the FT-IR transmission spectra. On the contrary, gamma-ray irradiated xCaO·(95-x)Al2O3·5Fe2O3 glasses (x=55∼60) show little change in the structure nor the IR transparency.
Structural Phase Transition of Ultrafine MnF2 Particles Induced by Size Reduction
Authors: Shunji Bandow Shunji Bandow
Published: February 2005

The metastable phase of MnF2 (MnF2-IV, α-PbO2 type) is formed with particles smaller than about 10 nm. The concentration of the MnF2-IV phase increases with decreasing particle size, and finally the MnF2-IV phase becomes dominant in 5 nm particles, in which very weak X-ray diffraction peaks of rutile-type MnF2 (MnF2-I) are detected. The largest particles (d∼14 nm) are dominated by the MnF2-I phase.
Influence of an As-Free Atmosphere in Migration-Enhanced Epitaxy on Step-Flow Growth
Authors: Hiroshi Yamaguchi Hiroshi Yamaguchi , Yoshiji Horikoshi Yoshiji Horikoshi
Published: February 2005

Reflection high-energy electron diffraction is observed during the growth of GaAs, AlGaAs, and InAs by migration-enhanced epitaxy on misoriented (100) substrates. The influence of an As-free atmosphere during Ga deposition in migration-enhanced epitaxy on step-flow growth is examined. Measurements of the change in specular peak intensity show that an As-free atmosphere accelerates step-flow growth, and that the ease with which step-flow growth occurs follows the order of InAs, GaAs, and AlGaAs. On the other hand, measurements of the specular peak width of the diffraction intensity profiles show that uniform step structures can be obtained for GaAs and AlGaAs layers under the same conditions if a small amount of As pressure is added during the metallic atom deposition in the process of migration-enhanced epitaxy.
Grain Growth and Electrical Properties in ZnO Varistors with Various Valence States of Additions
Authors: Chen Ying-Chung , Shen Chi-Yen , Chen Hone-Zern , Wu Yin-Fang Wei
Published: February 2005

Grain growth and electrical properties in ZnO system with various valence states of manganese and cobalt were studied. The results were discussed by means of defects produced by the additions. The grain growth was analyzed from the kinetic grain growth equation: G

n
=D
texp
(-E/R
T). In this work, the grain growth kinetic exponent n was 6 and activation energy was 230±21 kJ/mol. The grain size increased with the valence states of manganese and cobalt. The compositions with lower trap density have higher nonlinear coefficient, higher voltage ratio and lower leakage current. The varistor properties were improved by increasing the sintering temperature and time because of the more obvious tunneling effect.
Electron Energy Distribution Function in Fluctuating Plasmas
Authors: Takashi Kimura Takashi Kimura , Kazuyuki Ohe Kazuyuki Ohe
Published: February 2005

A method is proposed for detecting the electron energy distribution function (EEDF) of periodically fluctuating plasmas by averaging the time-resolved EEDF. The method is applied to detect the EEDF for externally excited and self-excited ionization waves in He positive columns of glow discharges. Good agreement is obtained between the EEDFs with and without the externally excited ionization wave.
Dissociative Excitation of GeH4 by Collisions with Krypton Active Species in the Flowing Afterglow
Authors: Tsuji Masaharu , Kobarai Kazunari , Kouno Hiroyuki , Obase Hiroshi , Yukio Nishimura Yukio Nishimura
Published: February 2005

The dissociative excitation of GeH4 by collisions with metastable Kr(3P2) atoms and Kr+ and (Kr+)* ions has been investigated in a flowing-afterglow reactor at 300 K. Ge* and GeH(A-X) emissions were observed in the 190-410-nm region. The total emission rate constants of Ge* and GeH(A2Δ) produced from the Kr(3P2)/GeH4 reaction were determined to be (2.6±0.3) and (0.71±0.07)×10-13 cm3s-1, respectively. When Kr+ and (Kr+)* ions were involved in the discharge flow, Ge* and GeH(A-X) emissions resulting from the primary (Kr+)*/GeH4 reaction and the secondary electron-ion recombination processes were observed. The rotational distribution of GeH(A) in the Kr(3P2)/GeH4 reaction was estimated from a spectral simulation.
Si Etching with Low Ion Energy in Low-Pressure Electron Cyclotron Resonance Plasma Generated by Longitudinal and Multipole Magnetic Fields
Authors: Shindo Haruo , Tetsuro Hashimoto Tetsuro Hashimoto , Yasuhiro Horiike Yasuhiro Horiike
Published: February 2005

Si etching at the low pressure of 5×10-5 Torr was studied employing a multipolar electron cyclotron resonance (ECR) plasma stabilized further by longitudinal magnetic field. Even at low pressure, the negative ion generated in the NF3 plasma greatly reduced the self-bias voltage. The self-bias of 25 V provided an anisotropic etching feature in NF3 alone. A further reduction of the bias voltage was made by changing the mirror magnetic field through control of the electron incoming flux, and at the lowest, the voltage of 14 V was attained. In this condition, the etched profile of the side wall became concave. However, the 20% O2 addition to the NF3 achieved the directional feature in the condition.
Development of High-Pressure Dilatometer for Polymer Studies
Authors: Taki Seiji , Takemura Tetuo , Kazumi Matsushige Kazumi Matsushige
Published: February 2005

A high-pressure and high-temperature dilatometer was developed by combining an S-type dynamic bellows cell and a high-resolution differential transformer and by setting them separately in two high-pressure vessels. It was revealed that the dilatometer is capable of observing the volume changes through the melting process in a typical polymer, polyethylene, at high pressures of up to 500 MPa.
Nanometer Patterning by Electron Beam Lithography Using an Amorphous Carbon Film as an Intermediate Layer
Authors: Shimizu Kazuhiro , Hideaki Nakakita Hideaki Nakakita , Shunri Oda Shunri Oda
Published: February 2005

Fifteen-nm-wide AuGe fine structures have been fabricated by 50 keV electron beam lithography using a 100 nm-thick amorphous carbon (a-C) film, which is helpful in reducing the effect of electron backscattering, inserted between the silicon substrate and resist.
YBaCuO Epitaxial Film Formation by Magnetron Sputtering with Facing Targets I. Effects of Target and Substrate Positions
Authors: Osamu Michikami Osamu Michikami , Masayoshi Asahi Masayoshi Asahi
Published: February 2005

YBa2Cu3O7-δ (YBCO) thin films were prepared on non-rotating MgO(100) substrates at 630°C using dc magnetron sputtering with facing targets (dc-MSFT) and the influence of target and substrate positions on film characteristics, such as superconducting properties, composition (C
Cu/Y, C
Ba/Y), crystallinity and uniformity was investigated. Spatial positions at which as-grown epitaxial films with T
ce=90 K were deposited were consequently found. Away from the center position, the composition of thin film deviated from a stoichiometric composition, that is, both C
Cu/Y and C
Ba/Y had a tendency to decrease. As-grown films with of T
ce over 88 K were obtained in a 5×5 cm2 area of the substrate. The deposition rate was about 20 Å/min at the center position and decreased by 22% at a position 2.5 cm away from the center.
Bi-Pb-Sr-Ca-Cu-O High-Tc Superconducting Fibers Prepared by the Pyrolysis of Organic Acid Salts
Authors: Shoyama Masashi , Hiroyuki Nasu Hiroyuki Nasu , Kanichi Kamiya Kanichi Kamiya
Published: February 2005

Bi-Pb-Sr-Ca-Cu-O high-T
c superconducting solid fibers were successfully prepared from the viscous mixture of organic acid salts containing oxide powders followed by the pyrolysis of organic acid salts. The addition of Pb efficiently enhanced the formation of the (Bi, Pb):Sr:Ca:Cu=2:2:2:3 phase. The T
c(end) of fibers was constantly over 100 K, the maximum T
c(end) being 108 K. The tensile strength of fibers with a T
c(end) of 108 K was 18 MPa.
Theory of Optical Second-Harmonic Generation in Slab Waveguides
Authors: Tomohiro Onda Tomohiro Onda , Ryoichi Ito Ryoichi Ito
Published: February 2005

A theory of optical second-harmonic generation in a slab waveguide with a nonlinear dielectric core is presented; two types of second-harmonic generation, the guided-mode and the Cerenkov-radiation types, are systematically treated on an equal basis. We have obtained exact analytical solutions for the field distribution and the power of TE-mode second-harmonic waves, neglecting the depletion of the fundamental waves and assuming isotropic and nondissipative mediums. Conditions for attaining high conversion efficiency are discussed on the basis of the results of numerical calculations.
The Effect of Doping on the Erasure Speed and Stability of Reversible Phase-Change Optical Recording Films
Authors: Fusong Jiang Fusong Jiang , Masahiro Okuda Masahiro Okuda
Published: February 2005

The crystallization kinetics of chalcogenide films, to which small concentrations of foreign elements such as Cu, Co, Pb, Ag and Sb are added, were investigated theoretically. It is found that the critical cooling rate can be taken as the criterion for evaluating the roles of various elements on the erasure speed. Since the elements having lower T
g/T
m possess higher critical cooling rates, they are favorable for enhancing the erasure speed of the above films. On the other hand, the T
g of the elements having lower T
g/T
m is found to be the main factor in determining the stability of corresponding films at room temperature because these elements possess higher crystallization speed in the temperature range between T
g and T
m. Therefore, the elements having lower T
g/T
m and higher T
g can be used to improve both the erasure speed and the stability of the reversible phase-change optical recording films.
Continuous-Wave Operation of a Lateral Current Injection Ridge Waveguide AlGaAs/GaAs Laser with a Selectively-Doped Heterostructure
Authors: Honda Yoshiaki , Suemune Ikuo , Naoki Yasuhira Naoki Yasuhira , Masamichi Yamanishi Masamichi Yamanishi
Published: February 2005

Continuous-wave operation of a lateral current injection ridge waveguide AlGaAs/GaAs laser with a selectively doped heterostructure was achieved by mainly improving the surface ohmic contacts after chemical etching. The laser threshold current under the pulsed operation was reduced to 6.5 mA, which is about a half of the threshold current in the previous laser structure.
Magnetic Anisotropy due to the Anisotropic Arrangement of Magnetic Particles in Magnetic Tapes
Authors: Masuda Morio , Kobayashi Shigeru Shiomi
Published: February 2005

Magnetic tapes were prepared by coating magnetic paint on polyethylene telephthalate (PET) films and drying it under a magnetic field. Spherical magnetite (Fe3O4) particles were dispersed in the paint. They exhibited remarkable uniaxial magnetic anisotropy with its easy axis parallel to the magnetic field. The experimental results suggested that the magnetic field produced the anisotropic arrangement of the magnetite particles and caused the uniaxial magnetic anisotropy. Theoretical derivation of the magnetostatic anisotropy energy was also attempted for the anisotropic arrangement of spherical magnetic particles.
Electron Beam Excitation of Cesium Fluoride Ionic Excimer
Authors: Xing Da , Ken-ichi Ueda Ken-ichi Ueda , Hiroshi Takuma Hiroshi Takuma
Published: February 2005

The vacuum ultraviolet fluorescence from an ionic alkali-halide excimer was observed by an electron beam excitation. A gas mixture of helium or neon with a hot vapor of cesium fluoride was excited to obtain two diffuse emission bands centered at 185 and 152 nm from Cs2+F-, which is isoelectronic to XeF excimer. The observed bands were assigned to the B-X and D-X transitions, respectively.
Potential Well Generated in Langmuir-Blodgett Heterofilm Consisting of Polar and Nonpolar Layers
Authors: Taro Hino Taro Hino
Published: February 2005

Voltage is applied in the surface direction of Langmuir-Blodgett (LB) heterofilms consisting of arachidic acid (C20, Y type, nonpolar) LB film and TCNQ-derivative (2-pentadecyl-7,7',8,8'-tetracyanoquinodimethane, C15·TCNQ, Z type, polar) or protoporphyrin IX dimethyl ester (PPDM, Z type, polar) LB film, and the voltage drop in the heterofilm is measured. As a result, a potential well is generated in the heterofilm of [nonpolar LB film/polar LB film], but no potential well is observed in the heterofilm of [polar LB film/nonpolar LB film] where the polar and the nonpolar LB films are deposited in reverse order of the former heterofilm.
High-Resolution Electron Microscopy on Epitaxial Pb(Mg1/3Nb2/3)O3 Film Prepared by Sol-Gel Method
Authors: Okuwada Kumi , Nakamura Shin-ichi , Kakuno Motomasa Imai
Published: February 2005

Highly oriented Pb(Mg1/3Nb2/3)O3 films prepared by the sol-gel method were studied with high resolution electron microscopy. The lattice image reveals epitaxial growth at the interface between the perovskite crystal and MgO single crystal substrate. A short-range ordered structure is ascertained to exist in the perovskite grains in the film.
Spatial Control of Electron Energy Distribution Function in a Magnetically Filtered Multicusp Plasma Source
Authors: Fukumasa Osamu , Hiroshi Naitou Hiroshi Naitou , Satoshi Sakiyama Satoshi Sakiyama
Published: February 2005

Using a movable magnetic filter, a technique to control plasma parameters spatially has been investigated in a multicusp plasma source. At any filter position, plasma parameters change steeply across the magnetic filter. Mainly, a multicusp plasma source is divided into two parts, i.e., a source plasma region with energetic electrons and a diffused plasma region. In the latter region, the high-energy component of electrons is eliminated thoroughly by the localized magnetic field of the filter.
Photoinduced Tellurium Precipitation in CdTe
Authors: Shunji Sugai Shunji Sugai
Published: February 2005

Tellurium precipitation in CdTe is found to be induced by photoirradiation with energy higher than the energy gap at 240 W/cm2. It is suggested that this photoinduced precipitation is related with the strong electron-phonon interactions, possibly self-trapped excitons. This irreducible tellurium precipitation may cause a serious problem for the life of semiconductor devices.
A New Interpretation of the Orientation Effect in GaAs Metal Semiconductor Field Effect Transistors
Authors: Huang Qing-An , Shi-Ji Lu Shi-Ji Lu , Qin-Yi Tong Qin-Yi Tong
Published: February 2005

This paper presents a new explanation of the orientation effect of self-aligned WSix gate GaAs MESFET's by taking the different channel-substrate interfaces formed in the [011] and [011̄] directions due to the piezoelectric charges in GaAs MESFET's into account. The predicted results are in agreement with the measurement data.
Growth of Polyhedral YBa2Cu3Ox Single Crystals and Their Anisotropic Properties
Authors: Takei Humihiko , Asaoka Hidehito , Yasuhiro Iye Yasuhiro Iye , Hiroyuki Takeya Hiroyuki Takeya
Published: February 2005

Polyhedral single crystals of oxide superconductor YBa2Cu3O
x
have been grown under the condition where the solid phase Y2BaCuO5 and liquid phase coexist. The crystals obtained possess well-developed habits and have a thickness of up to 3 mm along the c-axis, when the solid-melt mixture is kept at 1050-1010°C and then cooled to 990-970°C. The annealed crystals show a sharp superconductive transition at 91 K. The temperature dependence of resistivity is found to be metallic both in the ab- and c-directions. A marked anisotropy in the broadening of the resistive transition is observed under magnetic fields parallel or perpendicular to the c-axis.
The Effect of Microwave-Plasma on Decomposition and Oxidation of Ba(THD)2
Authors: Sugii Nobuyuki , Saito Shin'ichiro , Imagawa Kazushige , Saito Sakae , Keiichi Kanehori Keiichi Kanehori , Kazumasa Takagi Kazumasa Takagi
Published: February 2005

The effect of microwave-plasma on the decomposition and the oxidation of Ba(THD)2 is studied for estimating the possibility of low-temperature chemical vapor deposition of oxide superconducting thin film. Pseudo in situ auger electron spectroscopy clarifies that carbon-free film is grown with oxygen-plasma at over 400°C. Pseudo in situ electron diffraction analysis indicated that the film grown at over 400°C is crystalline BaO. These results support the possibility that oxide superconducting film can grow at around 400°C by chemical vapor deposition using THD complexes.
Tilt Angle Behavior of Smectic C Phase in Binary Systems
Authors: Koden Mitsuhiro , Anabuki Tohko , Kenichi Nakagawa Kenichi Nakagawa , Katsunobu Awane Katsunobu Awane
Published: February 2005

The tilt angle behavior of the smectic C phase was studied in several binary systems. The concentration dependence of the tilt angle deviated from the linear relationship. The degree of the deviation was influenced by the difference in the molecular structure between the two components. The tilt angles were found to correlate to the ratio of the SC-SA transition temperature to the SA-N (or I) transition temperature.
Interface Stability, Growth and Morphology in Icosahedral Quasi Crystals
Authors: Tsai An Pang , Chen Ho Sou , Akihisa Inoue Akihisa Inoue , Tsuyoshi Masumoto Tsuyoshi Masumoto
Published: February 2005

A planar growth with a growth direction parallel to a 5-fold symmetrical axis was found in a melt-quenched Al72Pd25Cr3 icosahedral alloy. An interpretation is given on the basis of a stability criterion that the plane perpendicular to the 5-fold axis is that of stable growth in an icosahedral phase (i-phase) and the solid-liquid interface instability occurs during solidification. It leads to the formation of cellular growth along the 5-fold axis and dendritic morphology. We find that decagonal phase (D-phase) grains nucleate from the i-phase and grow with the relationship that one of the 5-fold directions of the i-phase which have an angle of 63.43° between each other coincides with the 10-fold direction of the D-phase.
Low-Temperature Growth of Thin Films of Al2O3 by Sequential Surface Chemical Reaction of trimethylaluminum and H2O2
Authors: Fan Jia-Fa , Koji Sugioka Koji Sugioka , Koichi Toyoda Koichi Toyoda
Published: February 2005

Hydrogen peroxide (H2O2) was used as the oxidant in a sequential surface-chemical-reaction-limited growth system to obtain high-quality thin films of Al2O3. It is observed that trimethylaluminum (TMA) reacts with H2O2 readily at temperatures as low as room temperature, resulting in the identical growth of Al2O3 wherever the reactants reach. The films are highly insulating and ideally uniform.
Atomic Charge Distribution in Diamondlike Amorphous Carbon
Authors: Kugler Sándor , Náray-szabó Gábor
Published: February 2005

Based on semiempirical molecular orbital calculations, we propose an empirical formula for the calculation of net atomic charges in diamondlike amorphous carbon. These charges are in a linear relationship with bond angle distortions involving first and second neighbors. On the basis of the estimated charge fluctuation we predict that the integrated infrared absorption intensity will be within the range of 70000 to 120000 cm-2.
High Magnetic Flux Trapping by Melt-Grown YBaCuO Superconductors
Authors: Sawano Kiyoshi , Morita Mitsuru , Tanaka Masamoto , Sasaki Tsutomu , Kimura Keiichi , Takebayashi Seiki , Masao Kimura Masao Kimura , Katsuyoshi Miyamoto Katsuyoshi Miyamoto
Published: February 2005

Trapped magnetic flux density of melt-grown YBaCuO bulk superconductors was evaluated. A single-grained disc-shaped bulk sample with a size of 45 mmφ×15 mm trapped very high magnetic flux density after field cooling. One disc trapped a maximum surface flux density of 0.72 T, while the maximum of double-piled discs was 1.35 T after 100 seconds. A polygrained sample showed a much lower maximum. The pinning potential of this single-grained disc was 0.17 eV, and the overall critical current density estimated from the trapped flux density was about 7×103 A/cm2. Since these values are lower than those of a small-sized sample, weak links are still expected to exist even in the single-grained sample. Domain structure within a grain is a strong candidate for this weak link.
Microstructure and Superconducting Properties of Bi-Sr-Ca-Cu-O System Prepared by a Melt Process
Authors: Egawa Kunihiko , Umemura Toshio , Kinouchi Shin-ichi , Mitsunobu Wakata Mitsunobu Wakata , Shin Utsunomiya Shin Utsunomiya
Published: February 2005

The microstructure and superconducting properties for samples with the nominal composition of Bi2Sr2Ca1+2x
Cu2+x
O
y
(x=0, 0.2, 1.0) prepared by a melt process have been examined. The magnetic field dependence of the intragrain critical current density was improved by enriching the Ca and Cu contents. Such samples included two kinds of precipitates, (Ca, Sr)2CuO
y
and Sr-Pt-O compounds. The latter precipitates were much smaller in size than the former, and this suggests that they may be more effective in enhancing the pinning force.
Fabrication of Ag-Doped Y1Ba2Cu3O7-x Superconducting Films on Cu Substrates by Electrophoretic Deposition
Authors: Nojima Hideo , Shintaku Hidetaka , Masaya Nagata Masaya Nagata , Masayoshi Koba Masayoshi Koba
Published: February 2005

Ag-doped Y1Ba2Cu3O7-x
superconducting films were fabricated on Cu substrates by electrophoretic deposition. The electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x
and Ag2O powder dispersed in distilled acetone. The deposited films were heat-treated in air at 900°C. The Ag-doped Y1Ba2Cu3O7-x
films on Cu-coated YSZ exhibited a metallic temperature dependence of the resistance, and the zero-resistance state was obtained at 88 K. The critical current density and the grain growth were greatly improved by the Ag doping.
Photocarrier Generation Process of Phthalocyanine Particles Dispersed in a Polymer: Effects of Pigment Particle Size, Polymer Matrix and Addition of Fine γ-Alumina Particles
Authors: Saito Toshiro , Tsuneaki Kawanishi Tsuneaki Kawanishi , Atsushi Kakuta Atsushi Kakuta
Published: February 2005

In systems of phthalocyanine particles dispersed in polymer, the effects of pigment particle size, electric property of the polymer and addition of fine γ-alumina particles on photocarrier generation efficiency have been studied. With smaller pigment particle size and higher dielectric constant of the polymer, the photocurrent increased. Addition of γ-alumina particles also caused a considerable increase in the photocurrent. It seemed that photocarrier generation occurred at the surface of the pigment particles and adsorbed oxygen played an important role in the process.
Temperature Dependences of Effective Cone Angles of Surface-Stabilized Ferroelectric Liquid Crystal: Correlation with Layer Structure Changes Caused by Electrical Square Waves
Authors: Nagao Kazuya , Masako Yudasaka Masako Yudasaka , Takamasa Harada Takamasa Harada
Published: February 2005

When the layer structure of surface-stabilized ferroelectric liquid crystals in a SmC* phase was changed from a chevron to a quasi-bookshelf structure by applying an electric field at 50°C, the effective cone angle became 36.2° at 50°C. By cooling to 10°C, it became only 5° larger. This weak temperature dependence was reversible below 50°C, accompanied with reversible changes of the layer structures.
Measurement of Absolute Densities and Spatial Distributions of Si and SiH in an RF-Discharge Silane Plasma for the Chemical Vapor Deposition of a-Si:H Films
Authors: Tachibana Kunihide , Takuya Mukai Takuya Mukai , Hiroshi Harima Hiroshi Harima
Published: February 2005

Laser-induced fluorescence (LIF) spectroscopy has been applied to the detection of Si and SiH radicals in a silane plasma used in the chemical vapor deposition of a-Si:H films. Simple methods have been established for the calibration of the absolute densities. From the measured spatial distributions of those densities, the flux onto the substrate surface has been deduced. Based on these measurements, the contribution of Si and SiH radicals to the film growth is discussed in relation with the deposition rate, and it is concluded that, in quantity, these radicals do not contribute significantly to the deposition but may affect the quality of the films.
Fusion of Paramecia by Means of Altered Electrofusion
Authors: Hatakeyama Toyomasa , Yamaguchi Ichiro , Hiroshi Yagi Hiroshi Yagi , Hideo Matsuda Hideo Matsuda
Published: February 2005

We succeeded in fusion of paramecia by means of altered electrofusion. Some of the fused cells exhibited life activity and were able to perform several cell divisions. A daughter cell produced by the cell division was a singlet or a doublet and was able to proliferate its clones by repeating mitosis similar to the normal cell. On the other hand, a host fused cell showed distinct discrepancy in its form with elapsed time, according to the subtle difference of the contact between the original cells at the electrofusion.
High-Field Electron Transport in a-Si:H
Authors: Imao Shozo , Nakajima Shigeki , Nakata Jun-ichi , Hattori Reiji , Shirafuji Junji , Inuishi Yoshio
Published: February 2005

High-electric-field electron transport in a-Si:H films has been investigated by means of time-of-flight (TOF) measurements. The drift mobility increased with increasing applied field at lower temperature (≤300 K), accompanied by a simultaneous increase in the dispersion parameter resulting in nondispersive transport. The mobility was much less field-dependent at higher temperature where the nondispersive transport was attained. The experimental results are consistently explained by taking account of the increase in electron temperature (hot electron) at higher field into the theory of dispersive transport.
Short-Period Superlattices of (GaP)n(AlP)n Grown by Metalorganic Vapor Phase Epitaxy
Authors: Morii Akio , Ohno Isao , Kanda Atsushi , Arai Kazumasa , Tokudome Koichi , Hara Kazuhiko , Junji Yoshino Junji Yoshino , Hiroshi Kukimoto Hiroshi Kukimoto
Published: February 2005

Short-period superlattices of (GaP)
n
(AlP)
n
have been grown by metalorganic vapor phase epitaxy. X-ray diffraction measurements have confirmed the formation of the structures, where n ranges from 4 to 10. Low-temperature photoluminescence has shown characteristic emission peaks, which shift toward higher energies and tend to increase in intensity with decreasing n. These results, together with the band discontinuity between GaP and AlP which was estimated from that between GaP and Al0.6Ga0.4P, strongly indicate that the (GaP)
n
(AlP)
n
system forms the superlattices of a type-II band alignment.
Fabrication of S-N-S Junction with the Normal Layer of InSb
Authors: Hato Tsunehiro , Akaike Hiroyuki , Yoshiaki Takai Yoshiaki Takai , Hisao Hayakawa Hisao Hayakawa
Published: February 2005

Superconductor-semiconductor-superconductor weak links with a normal layer of InSb thin film were fabricated. A large normal resistance of 16 Ω and a critical supercurrent of 50 µA were obtained at 4.2 K for a channel length of 0.19 µm between Nb electrodes. The normal resistance of 16 Ω is about 40 times as large as that of a junction with the normal layer of a Si bulk crystal.
Formation of a Rotating Relativistic Electron Beam Using a Narrow Magnetic Cusp Field
Authors: Mizuno Takahide , Sekita Hitoshi , Kitora Masakazu , Naito Yoshihiko , Hirobumi Saito Hirobumi Saito , Tadashi Sekiguchi Tadashi Sekiguchi
Published: February 2005

Formation of a rotating, relativistic electron beam with properties suitable for a circular free electron laser has been studied. The rotating, relativistic electron beam is generated by the method of injecting a straight-moving, hollow, relativistic electron beam (typical energy 500 keV) into a magnetic cusp. By decreasing the axial transition width of the cusp, the beam off-centering motion is suppressed and the beam current is increased by a factor of 4 (from 50 A to 200 A).
Perception of 3-D Transparent Illusory Surface in Binocular Fusion
Authors: Masanori Idesawa Masanori Idesawa
Published: February 2005

A new discovery is the illusion of 3-D transparent surface perception in the binocular fusion. When adequate visual stimuli are suitably arranged partially along the surface boundary or are given beyond the occluding illusory surface, a transparent or translucent illusory surface can be seen. These phenomena are unique to binocular fusion and have been classified into three categories: glassy (crystal) transparency, semi-transparency and translucent. Optogeometrical arrangements for the perception of these transparent illusory surfaces were clarified. The transparency of these surface has been investigated by using illusory probe stimuli. These newly found illusory phenomena have a close relationship to the visual perception of the 3-D structure of space in binocular viewing and can offer a clue by which to reveal the mechanism underlying the 3-D space perceiving ability of the human visual system.
A New Method for Direct Determination of the Time Sequence of Nucleation from Spatial Pattern Divided by Spherulites
Authors: Tanaka Hajime , Fujioka Toshikazu , Nishi Toshio
Published: February 2005

Here we show a new method of digital image analysis for determining the time sequence of nucleation directly from a final pattern divided by spherulites. Since the growth rate of spherulite with dense-branching morphology is generally constant, the space-time relation is extremely simplified. The information on the time event is completely contained in the spatial characteristics of the pattern (the centers and boundaries of spherulites). We describe a simple algorithm for calculating the nucleation time sequence and its application to polymer spherulites. The method can be widely applied to the pattern divided by spherulites of any material.
Thin-Film Cold Cathode Using ZnS Layer
Authors: Okamoto Shinji , Eiichiro Nakazawa Eiichiro Nakazawa , Takeo Suzuki Takeo Suzuki
Published: February 2005

A new thin-film cold cathode (TFCC), which is composed of a Sn-doped In2O3/Ta2O5/ZnS/Au, has been investigated. The TFCC, which is different from the cold cathodes reported so far, causes electron emissions by electrons flowing across the ZnS layer by a high ac-field. An average emission current of 28 nA/cm2 has been obtained. To demonstrate the electron emission from the TFCC, cathodeluminescence from phosphor coated on an anode has been observed. The mechanism of the TFCC is also discussed.
Effect of Oxidizing Ambient on Oxygen Precipitation in Silicon Crystals
Authors: Masami Kohketsu Masami Kohketsu , Seiichi Isomae Seiichi Isomae
Published: February 2005

Interstitial oxygen (Oi) concentrations ([Oi]) are measured in silicon crystals subjected to three-step thermal treatments consisting of the first annealing in N2 at 1373 K, the second annealing at 973 K and the third annealing at 1273 K. When silicon surface is oxidized during the third annealing step in O2, oxygen precipitation is retarded in comparison with that obtained in N2. It is found that oxygen precipitation at 1273 K is more retarded with a decrease in [Oi] in silicon crystals. In addition, surface oxidation at 973 K (the second annealing) does not influence the formation of nucleation centers for oxygen precipitates.
High-Resolution Transmission Electron Microscopy of Initial Stage of Radiation Damage of YBa2Cu4Oy Induced by 1 MV Electron Beam
Authors: Matsui Yoshio , Yanagisawa Kasumi , Fujiwara Naohito
Published: February 2005

Radiation damage of the YBa2Cu4O
y
(124) superconductor induced by a 1 MV electron beam is examined by ultra high-resolution high-voltage electron microscopy. Small spots with nearly amorphous structure are formed mainly at the (CuO)2 double-chain layers at an early stage of irradiation, and their area gradually increases with irradiation time. It is considered that the amorphization is induced by direct knock-on displacements of atoms by collisions with a high-energy electron beam.
Fabrication of All-High-Tc Josephson Junction Using As-Grown YBa2Cu3Ox Thin Films
Authors: Harada Kanji , Myoren Hiroaki , Osaka Yukio
Published: February 2005

All-high-T
c Josephson junctions consisting of a YBCO/barrier/YBCO-layered structure using epitaxial YBCO films sputtered on MgO(100) have been successfully fabricated. The barrier layer was obtained by Ar+O2 plasma treatment of the surface of the base electrodes. These junctions show superconductor/normal-metal/superconductor (SNS)-like current-voltage characteristics. Constant-voltage current steps observed in response to 10 GHz microwave radiation show that ac-Josephson effects occur in these junctions.
New Interference Fringes Generated by Epitaxial Layers of Semiconductors and SIMOX (Oxygen-Ion-Implanted-Si) Wafers
Authors: Ogawa Tomoya , Taijing Lu , Toyoda Koichi
Published: February 2005

Truly new interference fringes generated by SIMOX (oxygen-ion-implanted silicon) wafers and hetero-epitaxial layers of semiconductors were originally and clearly observed. Generation of the new fringes was caused by interference between a part of the incident light pencil reflected from the top surface of a specimen and the light scattered from the hetero-interface after refraction of the other part of the pencil. The reflection from the top surface is fairly large due to the very high refractive index (more than 25% at most semiconductor surfaces) and the intensity of light scattered from the interface is strong enough for it to act as a plane source with coherency.
Picosecond Optical Pulse Generation from Mutually Coupled Laser Diodes by Synchronous Pump Mode-Locking
Authors: Kawaguchi Hitoshi , Hideyuki Iwata Hideyuki Iwata , Naohiro Tan-no Naohiro Tan-no
Published: February 2005

We propose and demonstrate a picosecond optical pulse generation from optically coupled laser diodes (LDs), for the first time, by synchronous pump mode-locking. Two LDs, having an antireflection coating on one facet, are mutually optically coupled, and form an external cavity (cavity length L
ext). By setting the phase difference in the modulation currents to π rad (frequency ∼c/2L
ext) injected into the two LDs, a pulse duration of as short as 7.2 ps is achieved with relatively high optical power (peak power ∼170 mW) from 1.3 µm InGaAsP/InP LDs.
High Temperature Rectifying Contacts Using Heteroepitaxial Ni Films on Semiconducting Diamond
Authors: Humphreys T. P. , Labrasca J. V. , Nemanich R. J. , Das K. , Posthill J. B.
Published: February 2005

The first results pertaining to the fabrication of high-temperature rectifying contacts using heteroepitaxial Ni films deposited on natural p-type semiconducting diamond substrates are reported. The contact diodes were deposited at 500°C by the thermal evaporation of Ni from a W filament in ultra-high vacuum. The epitaxial nature of the deposited Ni layers has been established from an inspection of in situ low-energy electron diffraction (LEED) patterns. The Ni films exhibit excellent adhesion properties with the underlying diamond substrate. As evidenced by current-voltage (I-V) measurements stable rectifying characteristics for the Ni/diamond contacts were observed in the 25-400°C temperature range.
Energy Distribution of Au- Ions Produced by Sputtering
Authors: Okabe Yushirou , Sasao Mamiko , Wada Motoi , Yamaoka Hitoshi , Junji Fujita Junji Fujita
Published: February 2005

The energy distribution of Au- extracted from a plasma-sputter type negative ion source was measured. The energy spread ΔE, which was defined as the FWHM of the observed negative ion energy distribution, increased with increasing target voltage (V
t). When V
t was about 280 V, the energy distribution agreed well with the Thompson-Sigmund (T-S) theory. For values of V
t less than 280 V, the high-energy component in the distributions fell off faster than those predicted by the T-S theory. This effect was exaggerated as V
t was further decreased. The ΔE for V
t below 280 V are less than 10 eV, which seems to be sufficiently small for application to a heavy ion beam probing (HIBP) method.
Effects of Phosphine-Plasma Treatment on Characteristics of Au/n-InP Schottky Junctions
Authors: Sugino Takashi , Yamamoto Hiroyuki , Sakamoto Yoshifumi , Hideaki Ninomiya Hideaki Ninomiya , Junji Shirafuji Junji Shirafuji
Published: February 2005

The effects of phosphine (PH3)-plasma treatment on the characteristics of Au/n-InP Schottky junctions are investigated and compared with those of hydrogen (H2)-plasma treatment. An enhancement of the barrier height of as high as 0.7 eV or more is found for Schottky junctions fabricated by the process consisting of plasma treatment, oxidation and Au evaporation. In the case of PH3-plasma treatment, no degradation of the ideality factor occurs and change in the barrier height is suppressed even after annealing at temperatures as high as 350°C. Formation of Schottky junctions is attempted by using an in situ process of H2-plasma treatment and metallization in order to reveal the effect of oxidation on variation in the Schottky barrier height. It is demonstrated that the enhancement of barrier height is due to the combined effects of H passivation of the surface defects and surface oxidation.
Chemical Shift in Optical Reflection Spectra Observed During III-V Semiconductor Metalorganic Chemical Vapor Deposition Growth by Surface Photo-Absorption Method
Authors: Naoki Kobayashi Naoki Kobayashi , Yoshiji Horikoshi Yoshiji Horikoshi
Published: February 2005

Spectral dependence of optical reflection from a growing surface is measured in situ during metalorganic chemical vapor deposition of As-based III-V semiconductors, InAs, GaAs, AlAs and AlGaAs by surface photo-absorption method. When one monolayer of group III atom is deposited on an As-stabilized surface, the spectral dependence of reflectivity change shows a chemical shift in the visible light region. The spectrum is red-shifted in the order of AlAs, AlGaAs, GaAs and InAs. The photon energy when the spectrum curve is rising correlates well with the heat of formation in group III atom-As tetrahedral bond, and is almost independent of the underlying layer composition. This result supports the assumption that the observed reflectivity difference between group III atom surface and As-stabilized surface in the visible light region is mainly caused by the photo-absorption process of the surface III-As chemical bond.
Strain Relaxation in MBE-Grown Si1-xGex/Si(100) Heterostructures by Annealing
Authors: Yaguchi Hiroyuki , Fujita Ken , Fukatsu Susumu , Yasuhiro Shiraki Yasuhiro Shiraki , Ryoichi Ito Ryoichi Ito
Published: February 2005

Strain relaxation in MBE-grown Si1-x
Ge
x
/Si(100) strained-layer heterostructures by postgrowth annealing has been investigated using X-ray diffraction and Nomarski microscopy. The extent of the strain relaxation is found to be dependent on Ge composition and annealing temperatures. The strain relaxation model proposed by Dodson and Tsao is applied to our experimental data and good agreement is obtained.
Development of New Electrochemical Synthesis of Oxides: Electrolytic Deposition of La2CuO4 Thick Layer on Zirconia Surface in Molten Salt
Authors: Nakamura Tetsurō , Natsuhara Masuhiro , Hitoshi Kawaji Hitoshi Kawaji , Mitsuru Itoh Mitsuru Itoh
Published: February 2005

A new method for electrochemical synthesis of oxides in molten salt was developed. The following galvanic cell was assembled and electrolysis was carried out at 973 K between the electrodes LaB6 vs Pt/O2 and between Cu vs Pt/O2 simultaneously.
Pt, LaB6
|80%KCl-14%NaCl-(6-x)%LaCl3-x%CuCl2|ZrO2(Y2O3)|O2, Pt
Pt, Cu
Formation of almost-single-phased La2CuO4 on the ZrO2(Y2O3) surface was confirmed when the ratio of electric currents passed through electrodes LaB6 vs Pt/O2 and Cu vs Pt/O2 was controlled to 3:1.1 and the molten salt composition was fixed at 80%KCl-14%NaCl-6%LaCl3.
Anisotropy in the Magnetic Penetration Depth of (103)YBa2Cu3O7-x Thin Films
Authors: Kohjiro Satoshi , Tachino Tetsuya , Hiroshi Akoh Hiroshi Akoh , Susumu Takada Susumu Takada
Published: February 2005

The anisotropy in the magnetic penetration depth λ at 4.2 K has been systematically investigated with (103)-oriented YBa2Cu3O7-x
thin films, using the resonator technique in transmission lines. The obtained values are λ=1.4±0.4 µm and λ=400±130 nm for the current flow across and parallel to Cu-O planes, respectively. This anisotropy ratio is in good agreement with the value estimated from the anisotropic resistivities of the films.