bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Lattice Modulations in the Tweed Structure of an Fe–Pd Alloy by Image Processing of a High-Resolution Electron Micrograph
Authors: Muto Shunsuke , Takeda Seiji , Oshima Ryuichiro
Published: February 2005

Computer-image processing of a high-resolution electron micrograph was carried out to extract information on the lattice distortions associated with the tweed structure of an Fe–Pd alloy which is a precursor phenomenon in the fcc-fct martensitic transformation. It was proven that the distorted and undistorted regions formed alternating layers parallel to {110} planes, as predicted by the continuum elasticity theory in a previous paper. The distorted layers contained tetragonally distorted strain centers with the tetragonality of about 0.97. This result coincides well with the `embryo model' proposed previously by the present authors' group.
Structures for Thermal Stress Reduction in GaAs Layers Grown on Si Substrate
Authors: Sakai Shiro , Kawasaki Koji , Wada Naoki
Published: February 2005

The structures to reduce the thermal stress in GaAs grown on Si substrates produced by the thermal expansion coefficient mismatch are proposed and analyzed by the finite-element method. It was shown that the stress can be below 1/10 of the stress in the planar GaAs on Si by partially separating the GaAs layer from the substrate. The preliminary experimental results show that this technique reduces the stress to 1/10 of the normal stress in the area of as wide as 200×250 µm2.
Substrate Bias Effect on Diamond Deposition by DC Plasma Jet
Authors: Matsumoto Seiichiro , Hosoya Ikuo , Chounan Takeshi
Published: February 2005

By applying positive bias voltage to a substrate in diamond CVD by a dc plasma jet of the Ar–H2–CH4 system, the deposition rate increased more than twofold, and the maximum rate of 15 µm/min was obtained. The deposition area also increased but the uniformity of film thickness did not improve. Applying the bias voltage to a ring electrode around the substate increased the deposition rate by nearly the same amount without increasing the substrate temperature.
A Simulation of Electron Scattering in Metals
Authors: Kotera Masatoshi , Ijichi Ryoji , Fujiwara Takafumi , Suga Hiroshi , Wittry David B.
Published: February 2005

A Monte Carlo calculation model is developed to simulate trajectories of primary and ionized electrons in metals. It is constructed especially for a quantitative analysis of images in the scanning electron microscope. We perform a direct simulation considering each differential scattering cross section for elastic scattering, inner-shell electron ionization, conduction band electron ionization and bulk plasmon excitation. The spatial distribution of secondary electron emission calculated is narrower than that of backscattered electron emission at the Al surface for 1 keV primary electrons, but depending on the condition, this tendency may not always be found. The spatial distributions of both secondary and backscattered electrons show the size effect, and if the specimen to be observed is smaller, the practical resolution will be better in the scanning electron microscope.
Micromachining and Device Transplantation Using Focused Ion Beam
Authors: Ishitani Tohru , Ohnishi Tsuyoshi , Kawanami Yoshimi
Published: February 2005

During the past ten years, a number of focused ion beam (FIB) applications in microelectronics have been demonstrated and steadily identified. In this paper, we will review FIB micromachining and device transplantation, in which processes of FIB sputtering, redeposition, and/or FIB-assisted deposition are well utilized. The FIB 3-dimensional micromachining is demonstrated with the aid of a sample rotator. Good prospects in the device transplantation are identified as a new high-resolution method for microdevice assembly and device repair. These FIB applications can be visually performed using scanning ion microscope (SIM) images. Specifications of the FIB apparatus for these applications and FIB micromachining simulation are also discussed.
Incorporation of Arsenic and Gallium in InP Layers in GaInAs/InP Heterostructures Grown by MOVPE
Authors: Wada Morio , Seko Masahito , Sakakibara Katsutoshi , Sekiguchi Yoichi
Published: February 2005

The effects of arsenic (As) and gallium (Ga) incorporation in InP layers in GaInAs/InP heterostructures grown by low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) on lattice parameter and band-gap energy of InP layers were studied. It was found that As and Ga incorporation is prolonged during InP growth after arsine (AsH3) and triethylgallium (TEG) flows are turned off, resulting in a lowering of the band gap energy and change in the lattice parameter of the InP layers. This incorporation is considered to originate from both desorption and diffusion of their outgassing sources produced during the growth of a thick GaInAs layer.
Negative Transconductance in AlGaAs/GaAs Heterojunction Bipolar Transistors
Authors: Nozu Tetsuro , Obara Masao
Published: February 2005

Negative transconductance has been observed and analyzed for the first time in AlGaAs/GaAs HBTs when V
BE is larger than 1.7 volts. A newly developed equivalent circuit model with an additional external base-emitter diode and a temperature-dependent resistor which corresponds to the intrinsic base resistance is proposed on the basis of experimental data for a pulse-biased I-V characteristic and temperature dependence of the sheet resistance for p-GaAs layers. Using this model, it is shown that negative transconductance is one of the novel characteristics in HBTs and is attributed to the drop in the input voltage across the intrinsic base resistance which increases with the input power through heat generation.
Crossed Grating Beam Splitter for Magnetooptical Pickup Head
Authors: Kawatsuki Nobuhiro , Uetsuki Masao
Published: February 2005

In the form of a crossed grating element (CGE) a novel beam splitter was fabricated by using a pair of holographic surface relief gratings with high spatial frequencies dually formed on a substrate plane. The CGE which acts as a beam splitter as well as a polarized beam splitter was experimentally assembled into a magnetooptical pickup head followed by investigation of optical properties.
Rapid Cooling Process in Thermooptic Effect of Smectic A-Cholesteric Mixed Liquid Crystals
Authors: Nawa Nobuhiko
Published: February 2005

The texture change in smectic A-cholesteric mixed liquid crystals has been investigated during a rapid cooling process from a cholesteric to a smectic A phase. At the cooling rate of 50°C/min, the initial focal conic texture in the cholesteric phase was transformed to the smectic scattering texture consisting of packed small domains.
Position Control of Electron Energy Loss Spectrum in Case of Accelerating-Voltage Fluctuation
Authors: Yoshida Kiyokazu , Takaoka Akio , Ura Katsumi , Fujita Hiroshi
Published: February 2005

In the parallel detection EELS, the fluctuation effect of the accelerating voltage is compensated both by the open loop and negative feedback controls. The fundamental frequency components of the AC power line and the excitation of Cockcroft-Walton circuit are canceled by applying the inverse-phase signal to the deflection coil, while the effect from the drift and the higher-order ripples is controlled by the negative feedback. The energy resolution is increased from 9.3 eV to 5.7 eV by the open loop control and can be improved up to 3.8 eV by the negative feedback. As the loop gain increases, the resolution increases at first, but then decreases. This decrease results from the shot noise of electron beam and the phase shift of the feedback loop. It is theoretically shown that the optimum condition to the loop gain and the bandwidth exists for the feedback control.
Third-Order Electric Susceptibilities of Halogen-Bridged Mixed-Valence Pt Complexes: [Pt(en)2][Pt(en)2X2](ClO4)4, X=Cl, Br, I, en=ethylenediamine
Authors: Wada Yoshiki , Yamashita Masahiro
Published: February 2005

Third-order electric susceptibilities, χ(3)
zzzz(-3ω, ω, ω, ω), of the halogen-bridged mixed-valence Pt complexes, [Pt(en)2][Pt(en)2X2](ClO4)4, (X=Cl, Br, I) are calculated using a three level model, taking account of the ground state and odd and even charge-transfer excitons. The values obtained are in the range of 10-12∼10-8 esu and are comparable to, or slightly larger than those observed in polydiacetylenes.
Dielectric Properties of γ-Ray Irradiated Poly(vinylidene Fluoride)
Authors: Nabata Yoshiyuki
Published: February 2005

The dielectric properties of γ-ray irradiated poly(vinylidene fluoride) (PVDF) were studied at temperatures from 213 to 423 K. The relaxation intensity, Δε, of both the β and α relaxations decreased with increasing irradiation dosages. The decrease of Δε in the β and α relaxations was ascribed to an increase in crosslinking in the amorphous regions and at lamellar surfaces, respectively. When irradiated PVDF was crystallized from the melt under uniaxial compression, Δε of the β relaxation increased with increasing compression ratio, while that of the α relaxation decreased. The increase of Δε in the β relaxation is explained by the increase of molecular chains oriented parallel to the film plane. The decrease of Δε in the α relaxation is due to conversion of form II crystal into form I.
Ultrasonic Investigation on Gd75Sc25 Single-Crystal Alloy with Antiphase Domain Structure
Authors: Takeuchi Jun , Hikata Akira , McKenna Mark J. , Elbaum Carles , Ito Takashi
Published: February 2005

Ultrasonic attenuation for Gd75Sc25 erhibits a sharp peak at the higher ordering temperature of T
c=185 K, whose shape and intensity depend on the thermal history and magnetic field strength. The results are interpreted by means of an antiphase domain ferrimagnetic structure. A peak in attenuation at T
c
1=77 K and another attenuation peak appearing in the intermediate temperature between T
c and T
c
1 under magnetic fields are also discussed.
Ballistic Electron Transmission in GaAs–AlGaAs Crossed Wire Junctions
Authors: Takagaki Yukihiko , Kusumi Yukihiro , Takaoka Sadao , Gamo Kenji , Murase Kazuo , Namba Susumu
Published: February 2005

Four-terminal resistances in narrow GaAs–AlGaAs crosses are investigated. The anomalies in the bend and Hall resistances give us information about the transmission of a ballistic electron in the cross. The transmission probabilities turning to the right and left side probes are kept comparable over a wide range of magnetic field, although the transmission probability for the motion straight on the cross is suppressed once the field is applied.
Compact and Powerful Plasma Generator
Authors: Masuzaki Suguru , Takamura Shuichi
Published: February 2005

A compact and powerful plasma generator was developed with the use of directly heated lanthanum hexaboride cathode which is composed of four units, convenient to handle, and designed to absorb thermal stress. A high plasma density of around 1×1019 m-3 was generated with a diameter of more than 10 cm in a cylindrical discharge chamber, appropriate for simulation studies on edge plasma physics.
Development of ac Calorimetric Method for Thermal Diffusivity Measurement III. Heat Loss in the Measurement of Fine Wires
Authors: Hatta Ichiro , Yao Haruhiko , Kato Ryozo , Maesono Akikazu
Published: February 2005

The measurement of the thermal diffusivity of a fine wire is developed, using a light-irradiation-type ac calorimetric method. It is pointed out that in the analysis, the contribution of heat loss or external relaxation time should be taken into account for the measurement of a fine wire. To examine the measurement, a wire of stainless steel with a diameter of 30 µm is used as a sample and the test is carried out in the wide frequency range of 1–25 Hz. The result obtained agrees with the value reported for the bulk material.
Dielectric Relaxation in Poly(vinylidene Fluoride): δ Relaxation
Authors: Nabata Yoshiyuki
Published: February 2005

The nature of the dielectric δ relaxation observed in poly(vinylidene fluoride) (PVDF) was examined. The δ relaxation was observed only in PVDF consisting of form II crystals. The intensity of the δ relaxation decreased with decreasing crystallinity in form II PVDF and also decreased upon annealing, which increases crystallinity and decreases the amount of crystalline defects. In a copolymer of vinylidene fluoride with form I structure, the δ relaxation was not observed. Thus, it was considered that the δ relaxation was related to molecular motion at disordered sites associated with crystalline defects in form II PVDF. These results are consistent with the mechanism of δ relaxation presented recently.
ESR Study on Silica Exposed to Glow-Discharge Plasma and UV Light
Authors: Kumeda Minoru , Nagano Hiroki , Shimizu Tatsuo
Published: February 2005

Silica glasses were exposed to glow-discharge plasma of various kinds of gases or to UV light from a low-pressure mercury lamp, and were investigated by ESR. In the case of the plasma exposure, the E' centers are created by UV light emitted from the plasma with photon energy smaller than the optical gap. After a long period of plasma exposure, the density of the E' centers decreases when hydrogen atoms supplied from H2 plasma and/or produced by dissociating OH species in the surface layer move into the inner part of the sample. In the case of the UV-light exposure, illumination time dependence of the E' center density varies with the OH concentration, suggesting that hydrogen plays a role in reducing the E' centers.
Interfacial Reactions of Ni, Si/Ni and Ni/Si Films on (100)GaAs
Authors: Iwakuro Hiroaki , Kuroda Tsukasa
Published: February 2005

The interfacial reactions of Ni, Si/Ni and Ni/Si films on GaAs have been investigated by X-ray photoelectron spectroscopy. In the 450°C-annealed Ni/GaAs system, the interfacial reaction occurred extensively, resulting in formation of the Ni-Ga, Ni-As and Ni-Ga-As compounds. In the annealed Si/Ni/GaAs system, the reaction began at both the Si/Ni and Ni/GaAs interfaces. The Ni silicide formed by intermixing at the Si/Ni interface play a role as a barrier film in preventing out-diffusion of the Ga and As atoms from the Ni/GaAs interface. On the other hand, in the Ni/Si/GaAs system, annealing produced intermixing at the Ni/Si interface but hardly any interfacial reaction at the GaAs substrate.
Experimental Study on Electromagnetic Interactions between Plasmas and a Vacuum Vessel during Disruptions in the Hitachi Tokamak HT-2
Authors: Abe Mitsushi , Takeuchi Kazuhiro , Fukumoto Hideshi , Shimizu Masashi , Otsuka Michio
Published: February 2005

Electromagnetic interactions between plasmas and a vacuum vessel during disruptions are examined experimentally in the Hitachi tokamak HT-2. Eddy currents which flow in the toroidal direction and poloidal coil currents are determined from the measured magnetic data. The currents enable calculation of the electromagnetic force on the vacuum vessel and resistively dissipated magnetic energy. Eddy currents and electromagnetic forces are mainly due to the plasma displacement (shell effect), not decay of the plasma current. Large plasma current quench rate -dI
P/dt is associated with scraping of the plasma by the inner limiter through the rapid plasma radial movement, and the decay rate in circular plasma is twice as large as that in elongated plasma. The magnetic energy dissipation is mainly due to the eddy current of the net toroidal current mode which is induced by large current quench rate.
Effect of Ambient Temperature on the MA and MG Processes in Ni–Zr Alloy System
Authors: Lee Chung Hyo , Mori Mitsuhiro , Fukunaga Toshiharu , Mizutani Uichiro
Published: February 2005

The mechanical alloying and mechanical grinding were carried out at three representative temperatures, i.e., one at low temperatures -180<T<-120, the second at 25°C and the third at a high temperature of 200°C, using the mixture of pure Ni and Zr powders at 50 at.% proportion and the NiZr2 intermetallic compound, respectively. The higher the ambient temperature, the faster the amorphization proceeds in the case of the MA process. This is attributed to the increasing interdiffusion rate at the interface of the two metals. An increase in ambient temperature is found to be effective also in the amorphization due to the MG process. The defects, which are produced and equilibrate under the milling at high temperatures, are the likely cause for the energization and amorphization of the intermetallic compound NiZr2.
Application of Modern Control Theory to Temperature Control of the MBE System
Authors: Ishikawa Takuya , Chan Yuen Chuen , Nakano Yoshiaki , Tada Kunio
Published: February 2005

A molecular beam epitaxy control system, whereby one microprocessor manages all the objects, has been constructed. The model-following algorithm, which is one of the applications of modern control theory, has been adopted instead of the conventional PID algorithm in order to improve the dynamic response of the temperature. It has been confirmed by computer simulation and measurement that the model-following algorithm is significantly effective especially when the set temperature is to be changed as a function of time. An application of the model-following algorithm to device fabrication has also been demonstrated.
Miniband Base Transistor
Authors: Nakagawa Tadashi , Takahashi Naoki , Kojima Takeshi , Ohta Kimihiro
Published: February 2005

A new type of transistor called the miniband base transistor is proposed and fabricated. The miniband base transistor uses, as an entire base layer, a superlattice of the same conduction type as an emitter and a collector. The superlattice base is designed so that the injected electrons are in the first excited miniband, while base current carriers are in the ground miniband. The minigap between these two minibands is expected to suppress LO-phonon scatterings and to increase the current gain. The transistor is fabricated using an AlGaAs/GaAs superlattice. Electrical measurements indicate that the superlattice base is effective for improving the current gain of the hot-electron transistor at small collector voltage.
A Parasitic Effect in Neutral Particle Diagnostic Using a Helium Probing Beam
Authors: Tobita Kenji , Kusama Yoshinori , Itoh Takao , Nemoto Masahiro , Takeuchi Hiroshi , Tsukahara Yoshimitsu
Published: February 2005

This paper describes the characteristic and the physical picture of a parasitic disturbance, which can occur because of the drift motion of probing beam ions trapped at the plasma edge, in active neutral particle measurements for magnetically confined fusion devices. In the JT-60 experiments, the disturbance is observed under the condition in which a neutral particle analyzer views the high recycling region, i.e., the divertor, and the occurrence of the parasitic effect is substantially dependent on the safety factor at the plasma boundary. Also discussed are the validity of our interpretation and some measures for avoiding the disturbance.
Temperature Dependence of Molecular Orientation and Hyperpolarizability in Hemicyanine LB Films Studied by Second-Harmonic Generation
Authors: Kajikawa Koutaro , Shirota Koichiro , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

The molecular orientational structure and the optical nonlinearity in mixed monolayers of hemicyanine and arachidic acid were investigated as a function of temperature by means of second-harmonic generation, linear optical absorption and X-ray diffraction. The average molecular tilt angle with respect to the surface normal has an inflection point in the temperature dependence for the films with low dye concentration. This phenomenon is explainable by the melting of arachidic acid. The molecular hyperpolarizability, β, shows a maximum at about 60°C in the films with a high dye fraction. This originates from the competition between the increase of β due to the dissociation of H-aggregates and the decrease of β due to protonation effect, the isomerization and decomposition.
A New Rotation Phenomena of Cells Induced by Homegeneous Electric Field
Authors: Hatakeyama Toyomasa , Yagi Hiroshi
Published: February 2005

When at least two plant protoplasts are located close to each other under homogeneous electric field, almost all of the cells rotate in the vicinity of its frequency of 10 kHz and specific cells in the vicinity of 10 MHz. The first rotation occurs in the plane constituted by the connecting line between two cells and the applied electric field line. This angular velocity increases with the square of the field strength. On the other hand, the second rotation or new rotation occurs in any plane and its angular velocity complicatedly depends on the field strength. Furthermore, when two cells are arranged in such a way that their connecting line is parallel to the applied field, the second rotation occurs but the first does not. The distinctive feature of the second rotation can be explained by the anisotropic dielectric in the cell due to the shape of its vacuole.
Effects of (NH4)2Sx-Pretreatment of GaAs Surfaces on Properties of Epilayers and Heterointerfaces in Pseudomorphic ZnSe/GaAs Gown by MOMBE
Authors: Wu Yi-hong , Kawakami Yoichi , Fujita Shizuo , Fujita Shigeo
Published: February 2005

We investigated the effects of (NH4)2S
x
-pretreatment of GaAs substrates on the properties of ZnSe epilayers and heterointerfaces in pseudomorphic ZnSe on GaAs by MOMBE. Compared to the pretreatment of GaAs substrates by a conventional method where thermal etching is employed as a cleaning process, (NH4)2S
x
-pretreatment resulted in (i) two-dimensional growth from an earlier stage of growth, (ii) better optical properties of pseudomorphic ZnSe epilayers, and (iii) better heterointerfaces. Thus, the interface state density near an energy level of 0.18 eV from the top of the valence band is estimated to be about 5×1011 cm-2·eV-1, and the density near the midgap is below the lower detection limit of Terman's method without post-annealing. These features show that this pretreatment technique is very promising for the fabrication of high-quality heterojunction devices.
Low-Threshold Strained-Layer InGaAs Ridge Waveguide Lasers
Authors: Takeshita Tatsuya , Okayasu Masanobu , Kogure Osamu , Uehara Shingo
Published: February 2005

Strained-layer InGaAs graded-index separate confinement heterostructure single-quantum-well (SQW) lasers have been fabricated. The threshold current dependence on cavity length using a 150- µm-wide broad contact laser yielded a transparency current of 49 A/cm2 and a differential gain coefficient of 10.8 cm/A, values which are both superior to those of conventional GaAs SQW lasers. A CW threshold current of fabricated 3- µm-wide ridge waveguide lasers was reduced to 2.8 mA by HR-HR coating at a lasing wavelength of 972 nm.
Quasicrystals in Al-Pd-TM (TM=Transition Metal) Systems Prepared by Rapid Solidification
Authors: Tsai An-Pang , Yokoyama Yoshihiko , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

An icosahedral phase with a face-centered six-dimensional hypercubic lattice (F-type) and a decagonal phase were found to be formed in rapidly solidified Al-Pd-TM (TM=V, Cr, Mn, Fe, Co, Mo, Ru, Re or Os) and Al-Pd-Co alloys, respectively. The formation of the mostly single quasicrystalline phases is limited to the narrow compositional ranges with e/a between 1.6 and 1.8. Neither the simple cubic (P-type) icosahedral nor amorphous phase was found in the Al-Pd-TM system. Thus, the effect of the group number of TM on the rapidly solidified structure in the Al-Pd-TM alloys is significantly different from that for Al-Cu-TM alloys. On the basis of the thermodynamic data, it is presumed that the strong chemical bonding nature among the constituent elements in the Al-Pd-TM alloys prevents the formation of P-type icosahedral and amorphous phases.
Control of Surface Color of Stainless Steel 304 by KrF Excimer Laser Implant Deposition
Authors: Sugioka Koji , Tashiro Hideo , Murakami Hideyuki , Takai Hiroshi , Toyoda Koichi
Published: February 2005

Surface coloring of stainless steel 304 by means of photochemical doping and simultaneous deposition using krypton fluoride excimer laser irradiation in ambient silane gas is demonstrated. The surface color is controlled by the deposited film thickness which is a function of the increasing number of laser pulses. The color change is a result of both the surface reflection and the absorption spectra of the films.
Oxidation of Si(100) Surfaces with Bi and Ag Overlayers
Authors: Yamada Tomoyuki , Abe Hitoshi
Published: February 2005

Desorption of Bi and Ag deposited on Si(100) surfaces has been investigated by Auger electron spectroscopy for heat treatment in an oxygen atmosphere. Bi was desorbed from the Si surface at substrate temperature T
s of 450∼500°C, and Ag was desorbed at T
s of 510∼560°C. The RHEED patterns for Ag overlayers before the desorption suggest that Ag atoms rearrange in the [011] direction.
Anomalous Force Dependence of AFM Corrugation Height of a Graphite Surface in Air
Authors: Ishizaka Tatsuya , Sugawara Yasuhiro , Kumagai Kozo , Morita Seizo
Published: February 2005

To investigate the force dependence of the AFM corrugation height of graphite under strong repulsive force, we measured the AFM corrugation height and tunneling current between the W lever and graphite surface simultaneously as a function of repulsive force up to ∼1.5×10-5 N. As a result, we found a peak of the AFM corrugation height at ∼1.1×10-5 N where the tunneling current showed a sudden increase. Even after the sudden increase of the tunneling current, we could observe atomically resolved AFM/PCM (point contact microscope) images simultaneously.
Fabrication of GaAs Ultrafine Gratings by Single-Layer-Masked SiCl4 Reactive Ion Etching
Authors: Li Guo Ping , Guo Liang , Katoh Takayuki , Nagamune Yasushi , Fukatsu Susumu , Shiraki Yasuhiro , Ito Ryoichi
Published: February 2005

A simplified technique has been developed for fabricating ultrafine GaAs gratings, exploiting electron-beam lithography, SiCl4 reactive ion etching (RIE) and single-layer masking. A 50-nm-thick single PMMA (polymethylmethacrylate) layer, directly exposed and not postbaked, is used as the etching mask. Using this technique, ultrafine diffraction gratings (period 60, 80, 120 nm) with good profile have been successfully fabricated on GaAs substrates. It is expected that the present technique will be applicable to the fabrication of finer structures such as quantum wires and dots.
Photo-Addressed Liquid Crystal SLM with Twisted Nematic ECB (TN-ECB) Mode
Authors: Sonehara Tomio
Published: February 2005

A novel photo-addressed LC-SLM featuring TN-ECB (twisted nematic electrically controlled birefringence) is presented. The LC-SLM consists of an a-Si photoconductor, a dielectric mirror and a TN-ECB liquid crystal layer. TN-ECB is a kind of ECB mode which has been developed by simulating light propagation in a reflective twisted nematic configuration. The features of the LC-SLM are 25 lp/mm resolution, high-speed response of less than 10 ms, and a single polarizer system. The resolution limitation by the dielectric mirror is also discussed.
Self-Diffraction by Two-Wave Mixing in Organic-Dye-Doped Film
Authors: Fujiwara Hirofumi , Shio Koji , Miyanaga Shigeki , Nakagawa Kazuo
Published: February 2005

Self-diffraction by nondegenerate two-wave mixing (TWM) in a saturable-dye-doped film is analyzed by means of a model of a three-level system for dyes. The rate equation approximation of a density matrix method leads to the electric polarization for nondegenerate TWM. Under the approximation of a strong pump limit and no pump absorption and depletion, the solution for the self-diffracted probe beam can be analytically obtained. The theoretical predictions are found to be in fair agreement with the experimental results.
Integrated Optic Digital Vector Processor Using Parallel Collinear Acousto-Optic Interactions
Authors: Goto Nobuo , Kanayama Yukihiro , Miyazaki Yasumitsu
Published: February 2005

An integrated optic processor to multiply vectors or matrices using multiple collinear acousto-optic interactions is proposed. When 200 wavelength-multiplexed signals are used to represent a 200-component vector, the processing rate to multiply a (200×200) matrix with a vector can be 9.8×109 [OPS] in a 16-bit number representation. A demonstration of a 2×2 processor is shown by an experiment with a channel-waveguide-type module.
An Approach to the Optical MSD Adder
Authors: Takahashi Hideya , Matsushita Kenji , Shimizu Eiji
Published: February 2005

Since the modified signed-digit (MSD) number system offers carry-free addition and subtraction, optical implementation of the MSD arithmetic can take full advantage of the intrinsic parallelism of optics. We suggest one optical MSD computation system. This system uses optical phase information so as to overcome negative value representation.
Optical Triple Matrix Multiplication Using Incoherent Orthogonal Imaging System
Authors: Huang Hongxin , Liu Liren , Wang Zhijiang
Published: February 2005

A novel scheme for performing triple matrix multiplication in parallel using an incoherent orthogonal imaging system is investigated mathematically. A typical configuration of triple matrix multiplication is given. The illustrating experiments are demonstrated.
Initial Stages of GaAs MBE Growth on Si(111)( √3×√3)-Ga Surfaces
Authors: Maehashi Kenzo , Hasegawa Shigehiko , Sato Masamichi , Nakashima Hisao
Published: February 2005

The initial stages of GaAs films grown by molecular beam epitaxy upon Si(111)( √3×√3)-Ga surfaces have been studied by reflection high-energy electron diffraction (RHEED), X-ray photoelectron spectroscopy (XPS), and angle-resolved ultraviolet photoelectron spectroscopy (ARUPS). RHEED observation reveals that the Si( √3×√3)-Ga surface changes into the (1×1) structure by As exposure at a substrate temperature of either 450°C or 250°C. XPS and ARUPS measurements indicate that the Si-Ga bonds are decomposed and Si-As bonds are formed instead by As exposure of the Si( √3×√3)-Ga surface. At the growth temperature of 250°C, deposition of 30 Å GaAs films causes a (2×2) superstructure.
Processing Properties of Integrated Optical Neural Computing Devices Using Graded Index Waveguides
Authors: Miyazaki Yasumitsu
Published: February 2005

Signal coupling and processing characteristics of new integrated neural computing devices consisting of a thin film waveguide with graded index distribution and control electrodes are shown. By using electrooptic, magnetooptic and acoustooptic effects, electromagnetic fields and acoustic waves, generated by electrodes at the optical beam focus, control of the neural coupling and processing of many input signals of optical beam that are incident to graded index film waveguides is possible.
Pressure-Effect Study on the High-Tc Superconductor Bi(Pb)-Sr-Ca-Cu-O System
Authors: Yoneda Takuji , Mori Yoshihisa , Akahama Yuichi , Kobayashi Mototada , Kawamura Haruki
Published: February 2005

Transiton temperatures (T
c) and lattice constants of Bi(Pb)-Sr-Ca-Cu-O superconductors have been determined by a magnetic susceptibility measurement and a high-pressure X-ray diffraction measurement as a function of pressure. The T
c of the high-T
c phase increases monotonically with an increase in pressure up to 4.5 GPa. The initial coefficient is 2.0 K/GPa, which agrees with that of the low-T
c phase reported previously. The linear compressibility along the c-axis direction, which is parallel to the bonding direction between the Cu atom and the apical oxygen, shows the same value for both phases.
Preparation of Tc=109 K Bi-Sr-Ca-Cu-O Superconducting Thin Films from Amorphous Bi-O/Sr-Ca-Cu-O Structures
Authors: Usuki Tatsuro , Yasui Ichiro , Yoshisato Yorinobu , Nakano Shoichi
Published: February 2005

The successful preparation of superconducting Bi-Sr-Ca-Cu-O thin films has been obtained by a new method based on an annealing process of amorphous Bi-O/Sr-Ca-Cu-O layers. Films of Bi-O were deposited on as-sputtered Sr-Ca-Cu-O films on MgO substrates by electron beam evaporation. These Bi-O films were diffused uniformly into Sr-Ca-Cu-O films for crystallization to Bi-Sr-Ca-Cu-O by annealing. A zero resistance temperature as high as 109 K was achieved for a 150 nm-thick sample, in spite of an absence of Pb.
High-Rate Deposition of Ferrite Films in Aqueous Solution by Light-Enhanced Ferrite Plating
Authors: Itoh Tomoyuki , Hori Seiichiro , Abe Masanori , Tamaura Yutaka
Published: February 2005

By irradiating the substrate surface with a Xe-lamp at 450 W/cm2, the deposition rate of Fe3O4 film in ferrite plating was increased by a factor of 10 (from ∼30 nm/min to ∼320 nm/min). The high deposition rate in light-enhanced ferrite plating cannot be simply ascribed to the increase of thermal energy.
Mössbauer Effect of Fe-Cu-Nb-Si-B Alloys Having High Permeability
Authors: Kohmoto Osamu , Haneda Koichi , Choh Tsutomu
Published: February 2005

Mössbauer spectra of finely crystallized Fe73.5Cu1Nb3Si13.5B9 alloys, produced by annealing their precursory rapidly quenched alloys, have been studied. The spectrum of the alloy annealed at 550°C consists of at least four composites of six absorption peaks. The hyperfine fields are obtained as 304, 275, 235, and 180 kOe. It is assumed that the Fe atoms have at least four kinds of local environments: ordered Fe3Si(I)-like, ordered Fe3Si(II)-like, α-Fe-like, and Fe2B-like and/or amorphous Fe3B-like environments.
Multiphoton Ionization of Xe and Kr Atoms by an ArF Excimer Laser
Authors: Kokubun Kiyohide , Ichimura Shingo , Shimizu Hajime
Published: February 2005

The dependence of ionization signals of Xe and Kr atoms on the laser intensity has been studied using an ArF excimer laser. For both atoms, we observe a slope of 2 in the log-log plot of the ionization signal versus laser intensity, and saturation of ionization at laser pulse energies higher than about 100 mJ (1.7×1010 W/cm2). The ionization of Kr can be interpreted as a 2-photon-resonant, 3-photon (2+1) ionization.
Multiple Beam Elements Using Linear Zone Plate Array Suitable for Parallel Optoelectronic Computing
Authors: Chen Jing Li , Kodate Kashiko , Kamiya Takeshi
Published: February 2005

A multiple spot imaging system which is composed of a combination of two orthogonal linear zone plate arrays is fabricated. Applications of the components such as optical modules as beam splitter and duplicator of image patterns suitable for optical computing are demonstrated.
Generation of Phase-Conjugate Wave in a Photorefractive GaP at 633 nm
Authors: Itoh Masahide , Kuroda Kazuo , Shimura Tsutomu , Ogura Iwao
Published: February 2005

Semi-insulating undoped GaP has a photorefractive response in the spectral region from 0.6 to 0.9 µm. The experiment of four-wave mixing has been carried out using a 633 nm He-Ne laser. The phase conjugate reflectivity was 0.3% at maximum. We measured the rise and decay time constants of the phase-conjugate wave generation by directly observing the temporal behavior of the signal on an oscilloscope. The time constants depend on the optical power and arrangement and is estimated to be 5 to 50 ms. From the dependence of the phase-conjugate reflectivity on the pump beam intensity ratio, the coupling constant was estimated as 0.4 cm-1.
New Preparation Process of V2O5 Thin Film Based on Spin-Coating from Organic Vanadium Solution
Authors: Shimizu Youichi , Nagase Katsumi , Miura Norio , Yamazoe Noboru
Published: February 2005

A new wet process was developed for preparing a V2O5 thin film for use in an electrochromic display device. V2O5 powder was dissolved into a mixed solution of benzyl alcohol and iso-butanol to obtain a vanadium solution, which was then spin-coated on an ITO glass followed by a heat treatment at temperatures above 300°C, preferably at 400°C. The resulting crystalline V2O5 thin film was excellent in reversibility of the electrochromism.
Photoinduced Solubilization of Conducting Polymer and Its Application to Etching and Recording
Authors: Yoshino Katsumi , Kuwabara Takao , Manda Yasuhisa , Nakajima Shigeaki , Kawai Tsuyoshi
Published: February 2005

Nonsoluble parts of conducting poly(3-alkylthiophene) become soluble into organic solvents upon irradiation of light of photon energy larger than the band gap. The applications of this novel effect to the etching of conducting polymers and also to the optical recording method have been proposed.
Amorphous-Silicon Thin-Film Transistors Using Chemical Vapor Deposition of Disilane
Authors: Breddels Paul A. , Kanoh Hiroshi , Sugiura Osamu , Matsumura Masakiyo
Published: February 2005

Amorphous silicon layers have been deposited by low pressure chemical vapour deposition at 450°C using disilane as the only source gas. Simple inverted staggered thin-film transistors were made with thermal silicon dioxide as the gate insulator. Field-effect mobilities for electrons and holes were 1.4 cm2/V ·s and 0.1 cm2/V ·s, respectively. In order to obtain these high mobilities the transistor structures were carefully annealed in a hydrogen-radical rich ambient.
Interference Effects on Photoreflectance Line Shapes of Excitons in GaAs/AlAs Superlattices
Authors: Nakayama Masaaki , Tanaka Isao , Doguchi Tomonori , Nishimura Hitoshi
Published: February 2005

We have investigated photoreflectance and reflectance line shapes of heavy-hole and light-hole excitons with quantum number n=1 at 77 K in (GaAs)
m
/(AlAs)
m
superlattices (m=35 and 53 monolayers) grown by molecular-beam epitaxy. The photoreflectance and reflectance line shapes of the superlattice with m=53 are fully reversed to those of the superlattice with m=35. It is demonstrated that the difference of the photoreflectance line shapes is due to a Fabry-Perot-type interference effect causing the difference of the reflectance line shapes.
Formation of InP Metal-Insulator-Semiconductor Schottky Junctions by UV Laser-Induced Photolytic Process of Phosphine Gas
Authors: Sugino Takashi , Ito Hiroyuki , Shirafuji Junji
Published: February 2005

It is shown by Auger electron spectroscopy analysis that the ArF excimer laser photolytic process of phosphine (PH3) gas is capable of removing native oxide and simultaneously depositing amorphous P film on an InP surface. The barrier height of Au-InP Schottky junctions with a thin P layer is found to increase to 0.73 eV from 0.48 eV in the case of untreated Schottky diodes. An enhancement of the barrier height is attributed to a metal-insulator-semiconductor (MIS) Schottky structure. In addition, it is demonstrated that the present procedure is suitable for hydrogenation of InP surfaces without surface degradation due to P dissociation.
Submillimeter-Wave Response of Nb-YBaCuO Point-Contact Josephson Junctions Using YBaCuO Thin Films Prepared by CVD
Authors: Imai Syozo , Sugawara Nobuhiro , Sumiya Kazushige , Ito Kimihiko , Mikoshiba Nobuo , Yamane Hisanori , Hirai Toshio , Kurosawa Hideyuki , Yamashita Tsutomu
Published: February 2005

The Shapiro steps in the submillimeter wave (SMMW) region were measured in point-contact Josephson junctions made of a Nb strip with a sharpened edge and a YBaCuO thin film. The thin film was prepared by the chemical vapor deposition (CVD) method. The dependence of the Shapiro step width on the SMMW power was measured for the wavelength of 570.6 µm (525.4 GHz). The dependence was similar to that found in microbridges made of low T
c superconductors. The first-order Shapiro step was observed for the wavelength of 232.9 µm (1.287 THz).
The Influences of Ag Addition on Superconducting Properties and Tensile Strength for Bi-Sr-Ca-Cu-O Fibers Prepared by Pyrolysis of Organic Acid Salts
Authors: Nasu Hiroyuki , Shoyama Masashi , Kamiya Kanichi
Published: February 2005

The influences of Ag addition on superconducting properties and tensile strength for Bi-Sr-Ca-Cu-O fibers prepared from the mixture of organic acid salts and oxide powders were investigated. The value of T
c(end) of fibers considerably increased to 72 K from 58 K for fibers without Ag2O addition and the tensile strength slightly increased. These results are attributed to Ag addition enabling the annealing to 840°C.
Hybrid Associative Memory Using an Incoherent Correlation System
Authors: Taniguchi Masaki , Matsuoka Katsunori , Ichioka Yoshiki
Published: February 2005

We present a hybrid heteroassociative memory using an incoherent system in which two correlators and a nonlinear element form a nonlinear feedback system. This system is simple and easy to compose. Any pattern can be recalled from an input pattern without cross talk or ghosts by properly designing a pair of filters installed in the correlators. To ensure the operation of this system and to demonstrate the usefulness of the proposed system, we performed some experiments by a simple hybrid system. Some experimental results are shown.
Surface Diffusion Coefficients on Stranski-Krastanov Layers
Authors: Zinke-Allmang Martin , Stoyanov Stoyan
Published: February 2005

Quantitative surface diffusion coefficients in clustering systems are of crucial importance for thin film growth applications. In this letter we report the first determination of the activation energy for surface diffusion on the Stranski-Krastanov layer in a technological important heterosystem. The findings are based on previously published independent measurements of the activation energy for cluster growth and cluster formation from the free adatom concentration. For the Stranski-Krastanov layer thickness of Ge on Si(100) we obtain 3.08±0.16 monolayer equivalent coverage and for the activation energy of surface diffusion 0.84±0.14 eV.
A Buried-Collector Layer by Arsenic Diffusion from an Oxidized Arsenic-Implanted Amorphous Silicon
Authors: Tsunoda Yoshihiro
Published: February 2005

The development of a buried-collector layer by arsenic diffusion from oxidized arsenic-implanted amorphous silicon and the effect of solid phase epitaxy (SPE) layer formation on the quality of the arsenic-diffused buried collector are elucidated. To break up the native oxide and to grow the SPE layer at the interface, the arsenic pile-up during the oxidation of the arsenic-implanted chemical vapor deposition (CVD) silicon is necessary. The crystallinity of the buried layer formed by the arsenic diffusion from the oxidized arsenic-implanted amorphous silicon is superior to that formed from the oxidized arsenic-implanted polysilicon.
Effect of Zn Partial Pressure during Growth on Electrical Properties of ZnSe Crystals Grown from the Melt
Authors: Kikuma Isao , Kikuchi Atsushi , Furukoshi Mitsuo
Published: February 2005

This paper describes the melt growth of ZnSe crystals by a modified Bridgman method under argon pressure. A definite Zn partial pressure over the melt is maintained by controlling the temperature of a Zn zeservoir. Electrical properties of as-grown crystals depend on the temperature of the reservoir. Low-resistivity n-type crystals are obtained when the temperature of the reservoir is kept above 1040°C during growth. The resistivity of the crystals is 0.2 to 5 Ω·cm and the Hall mobility is 380 to 500 cm2/V ·s at room temperature (290±5 K). The temperature of the Zn reservoir during the cooling process after solidification also affects the electrical properties.
Photoluminescence Study of Electron Wave Confinement in Multi-Quantum Barrier (MQB)
Authors: Takagi Takeshi , Koyama Fumio , Iga Kenichi
Published: February 2005

We have confirmed the enhancement of electron wave confinement of GaAs/AlGaAs multi-quantum barrier (MQB) using photoluminescence (PL) measurement. We observed less saturated PL excitation dependence and less sensitive temperature dependence. This could be due to the quantum enhancement in the potential barrier of the MQB structure, and shows a superior carrier confinement of MQB over a classical bulk barrier.
Characterization of Oxygen Precipitates in CZ-Silicon Crystals by Light-Scattering Tomography
Authors: Katayama Ken-ichi
Published: February 2005

The density and light-scattering intensity of oxygen precipitates in CZ silicon crystals are measured by IR light-scattering tomography. The numerical data clarified through the measurements are discussed in relation to the amount of precipitated oxygen. The results obtained here correspond well with the theoretical analysis that oxygen precipitates cause light to scatter. The information obtained by IR light-scattering tomography explains very well the precipitation process of oxygen in CZ silicon crystals, and the densities of precipitates obtained by this method are reliable.
Realization of Abrupt Interfaces in Si/Ge Superlattices by Suppressing Ge Surface Segregation with Submonolayer of Sb
Authors: Fujita Ken , Fukatsu Susumu , Yaguchi Hiroyuki , Igarashi Takayuki , Shiraki Yasuhiro , Ito Ryoichi
Published: February 2005

Atomic mixing in Si/Ge strained-layer superlattices is investigated by means of SIMS and XPS. The interfacial mixing is attributed to the surface segregation of Ge atoms during MBE growth of Si overlayers. It is demonstrated that the surface segregation is remarkably suppressed by depositing submonolayer Sb atoms on Ge layers prior to Si overgrowth and that Ge layers are confined to within 0.8 nm.
Addition of New Pinning Center to Unidirectionally Melt Solidified Y-Ba-Cu-O Superconductor
Authors: Shimoyama Jun-ichi , Kase Jun-ichiro , Kondoh Shinji , Yanagisawa Eiji , Matsubara Toshiya , Suzuki Mitsuru , Morimoto Takeshi
Published: February 2005

Y-Ba-Cu-O bulk superconductor including small particles of BaSnO3 was synthesized by the unidirectional melt solidification method. Finely dispersed Y2BaCuO5 precipitates and BaSnO3 particles were observed in YBa2Cu3O
y
matrix. The critical current density at 77 K in 8 kOe was 1.8×104 A/cm2, which was about four times higher than that of the BaSnO3-free specimen. Fine particles of BaSnO3 (0.1–1 µm) can act as effective flux pinning centers in the specimen and result in an increase of the critical current density.
Structural Change of Crystalline Porous Silicon with Chemisorption
Authors: Ito Toshimichi , Yasumatsu Tatsuro , Watabe Hirokuni , Hiraki Akio
Published: February 2005

Anodized porous silicon (PS) has been investigated in relation to its structural change at elevated temperatures of ≦1100°C in a vacuum by means of infrared spectroscopy, scanning electron microscopy, X-ray diffraction and gas adsorption techniques. The structural change observed is strongly dependent on foreign atoms chemisorbed or bonded to Si atoms on the pores in PS; in the case of chemisorption of H atoms, a significant change in the pore structure is induced, while in the case of O, the formation of thin oxide walls (1–2 nm) prevents Si atoms from moving about. These results are compared with molecular orbital calculations (AM1 method) for Si14H20 and its related clusters. The importance of the surface energy is consistently indicated for the structural change observed.
Lattice Parameter Measurement of GaAs Crystals Using Monochromatic Synchrotron Radiation
Authors: Usuda Koji , Yasuami Shigeru , Higashi Yasuo , Kawata Hiroshi , Ando Masami
Published: February 2005

A high-resolution diffractometer with a monolithic Si monochromator was developed for lattice parameter (d) measurements using synchrotron radiation. The accuracy attained was 5.9×10-6 in terms of Δ
d/d. This degree of accuracy makes it possible to discuss the lattice parameter variation due to composition shifts in GaAs crystals. However, a preliminary study implied that thermally-induced elastic strain affects the lattice parameter more than the material composition shifts for crystals with the 104∼105 cm-2 order of dislocation density.
Effect of Visible-Light Illumination on the Growing Surface of an a-Si:H Film in Plasma Decomposition of SiH4
Authors: Yamanaka Mitsuyuki , Hayashi Yutaka , Sakata Isao
Published: February 2005

Light from a tungsten valve illuminated the growing surface of an a-Si:H film. The a-Si:H film was deposited by plasma decomposition of SiH4 in a specially designed plasma CVD system with a pair of comb-type glow discharge electrodes through which light can illuminate the surface of the heated substrate. Compared with nonillumination-grown films, the films grown under illumination exhibited smaller photo-induced changes in photoconductivity and had less bonded hydrogen content, a smaller ratio of dihydride/total bonded hydrogen, but sometimes higher space-charge density calculated from quasi-static capacitance-voltage characteristics of a Au-electrode Schottky diode on the film.