bluuebunny/crossref_metadata_2025 huggingface dataset:
A Self-Aligned Mo-Silicide Formation
Authors: Nagasawa Eiji , Okabayashi Hidekazu , Morimoto Mitsutaka
Published: November 2005

Mo-silicides, formed by a new technique combining ion implantation through metal film (ITM) to induce metal/Si interface mixing and also to form doped layers with appropriate subsequent annealings, were found to have excellent properties in film uniformity and self-aligned formation for exposed Si areas (contact holes). These excellent silicidation properties in the ITM technique were also confirmed for patterned poly-Si silicidation. Lateral silicide growth out of contact holes, usually observed in silicidation using mere thermal reaction of refractory-metal/Si structures, was markedly suppressed in the ITM silicidation.
Photo-Thermal Spectroscopy of Thin Solid Films
Authors: Tanaka Keiji , Satoh Ryoh , Odajima Akira
Published: November 2005

A novel photo-thermal spectroscopic method has been developed for determining the optical absorption coefficient of thin films. The temperature rising in the film illuminated with monochromatic light is measured with thin film thermocouples, and the thermo-electric voltage is employed to calculate the absorption coefficient. For a 1 µm-thick amorphous As2S3 film, the coefficient can be determined down to 5×102 cm-1 at desired temperatures.
Two-Dimensional 4×4 Optical Fiber Array Applied to a Monolithic LED Array
Authors: Nobuhara Hiroyuki , Sugahara Tomonobu , Wada Osamu , Sakurai Teruo
Published: November 2005

A new method of fabricating two-dimensional optical fiber array which realizes fiber arrangement accuracy within ±10 µm is presented. A monolithic light emitting diode (LED) array is coupled to a 4×4 fiber array prepared by the present method. The coupled light output is measured to be highly uniform, exhibiting a variation of less than ±5%.
Molybdenum Film Formation by Low Pressure Chemical Vapor Deposition
Authors: Yasuda Kazumitsu , Murota Junichi
Published: November 2005

A new low pressure chemical vapor deposition apparatus for molybdenum film formation by the hydrogen reduction of molybdenum pentachloride is developed. The apparatus realizes the uniformity of film thickness within ±5% for 25 wafers per batch and molybdenum film formation without oxidation. It is found that the deposition rate is controlled by surface reaction up to a higher temperature than that under atmospheric pressure and is proportional to the 3/2 power of hydrogen partial pressure in the region of surface reaction.
Photoluminescence of AlxGa1-xAs/AlyGa1-yAs Multiguantum Wells Grown by Pulsed Molecular Beam Epitaxy
Authors: Kawabe Mitsuo , Kondo Masahumi , Matsuura Nobuyuki , Yamamoto Kenya
Published: November 2005

Multiquantum wells (MQW) with a structure of Al
x
Ga1-x
As/Al
y
Ga1-y
As were grown by pulsed molecular beam epitaxy in order to raise the emission energy in MQW of the AlGaAs system. Sharp photoluminescence spectra indicate the high quality of MQW structure and the peak emission energy agreed with the calculated value of n=1 electron and hole transition.
A New Josephson Timed Inverter with Four-Junction Logic (4JL) Gate
Authors: Sogawa Ei-ichi , Nakagawa Hiroshi , Takada Susumu , Hayakawa Hisao
Published: November 2005

A new timed inverter with a simple structure and a wide operating margin has been developed. It is composed of a 4JL gate with a single limiting junction connected to the input terminal of the gate. The threshold characteristics and operating sequences have been investigated theoretically. Successful logic operation of the inverter has been performed with an operating margin of ±33% against both input and timing signals.
Focused Si Ion Implantation in GaAs
Authors: Bamba Yasuo , Miyauchi Eizo , Arimoto Hiroshi , Kuramoto Kazuo , Takamori Akira , Hashimoto Hisao
Published: November 2005

A 160-keV, submicron-focused Si ion implantation in MBE-GaAs was made using a 100 kV maskless implanter with a Au–Si–Be alloy ion source. Obtained Raman spectra indicated that compared with the implantation current densities of an unfocused ion beam, the higher current density (about 104 times greater) of the focused beam resulted in less implantation-induced and residual (after annealing up to 500°C) damage. Moreover, 850°C annealing led to a higher electrical activity of focused implanted Si-ions but almost the same optical quality of conventional implantation.
Deep UV Ablation of PMMA Resists
Authors: Lanagan M. , Lindsey S. , Viswanathan N. S.
Published: November 2005

Deep UV exposure of Polymethyl methacrylate resist systems has been investigated in the spectral region 220–250 nm using a special deep UV light source. The ablation of PMMA resist follows a quantitative exponential relation and is independent of molecular weight and substrates. The erosion rates at higher temperatures show a dependence on the Tg of the PMMA. The ablation suggests depolymerization reactions in PMMA concurrent to chain scission. Reaction pathways in deep UV degradation are different from electron beam and ion beam degradations of PMMA.
A New High-Electron Mobility Monolayer Superlattice
Authors: Yao Takafumi
Published: November 2005

A new high electron mobility monolayer superlattice (MSL) which consists of alternating InAs and GaAs monolayers is proposed. Since the disorder scattering inherent in mixed crystals is absent in the MSL's, extremely high electron mobility can be expected. Critical periodicity (well width+barrier width) of the MSL is estimated to be 16 monolayers, below which electronic structure of the MSL becomes three dimensional. A calculation shows that the electron mobility of the MSL will be as high as 6×105 cm2/V.sec at around 50 K for N
D-N
A=1×1014 cm-3 and N
A/N
D=0.5, which is more than one order of magnitude higher than In0.5Ga0.5As alloy with the same impurity concentration.
Electrical Properties of Focused-Ion-Beam Boron-Implanted Silicon
Authors: Tamura Masao , Shukuri Shoji , Tachi Shinichi , Ishitani Tohru , Tamura Hifumi
Published: November 2005

Electrical properties of 16 keV, focused-ion-beam (FIB) (beam diameter: 1 µm, current density: 50 mA/cm2) boron-implanted silicon layers have been investigated as a function of beam scan speed and ion dose, and compared with those obtained by conventional implantation (current density: 0.4 µA/cm2). High electrical activation of the FIB implanted layers is obtained by annealing below 800°C as a result of the increase in amorphous zones created in the implanted layers. Amorphous zone overlapping is assumed to occur at FIB implantation doses of 3–4×1015 ions/cm2 from the results of electrical activation and the carrier profile of implanted regions annealed at low temperature, if beam scan speed is lowered to about 10-2 cm/s.
Stationary Large Area Exposure in Synchrotron Radiation Lithography Utilizing a New Arrangement of Magnets Applied to the Storage Ring
Authors: Tanino Hiroshi , Hoh Koichiro
Published: November 2005

A new arrangement of magnets called the sliding-wiggler in a storage ring dedicated to lithographic purposes is proposed. The exposure can be enlarged up to an area of 100 mm × 100 mm stationarily. Most of the emitted radiation is utilized and the throughput will be more than thirty times as much as with commercial bending magnets.
Interaction of Point Defects with Hydrogen in Germanium
Authors: Ito Kazuyoshi , Corbett James W.
Published: November 2005

The defect levels produced in undoped germanium crystals by implantation with 50 keV hydrogen ions of irradiation with 1.5 MeV electrons and the annealing behaviour of the materials were studied by DLTS technique. The positions or the trap levels and the cross sections of hole trapping of these traps were determined. The level located at Ev+0.42 eV produced by electron irradiation should be ascribed to a divacancy. In the samples implanted with hydrogen ions, the trap levels at Ev+0.38 eV and Ev+0.42 eV annealed at the same temperature. The two traps are attributable to the defect levels associated with a divacancy-hydrogen complex.
Landau Damping of the Longitudinal Coupled-Bunch Instability in an Electron Storage Ring
Authors: Miyahara Yoshikazu , Asaoka Seiji , Isoyama Goro , Mikuni Akira , Nishimura Hiroshi , Soda Kazuo , Kanzaki Hiroshi
Published: November 2005

A longitudinal coupled-bunch instability of the beam current in an electron storage ring was damped successfully by using a Landau cavity. This results in the reduction of beam size and the suppression of the slow fluctuation of the synchrotron radiation
Far-Infrared Magneto-Absorption of the Nonequilibrium Electron System in Indium Phosphide
Authors: Ohyama Tyuzi , Otsuka Eizo , Yamada Syoji , Fukui Takashi , Kobayashi Naoki
Published: November 2005

Measurements of the far-infrared cyclotron resonance of conduction electrons and the Zeeman absorption of donors in a MOCVD grown InP have been carried out at 4.2 K under photo- and electric field-excitations. It is found that the effective mass of the electron and the donor binding energy arem*=(0.0817±0.0004)m0andEb=7.6 meV, respectively. The electric field dependence of the resonance intensity can be explained in terms of impact ionization of the donor electrons. From time-resolved experiments, both the apparent lifetime and the scattering time of photoexcited electrons are also obtained.
A Segmented Electrode Multi-Quantum-Well Laser Diode
Authors: Iwamura Hidetoshi , Tarucha Seigo , Saku Tadashi , Horikoshi Yoshiji , Okamoto Hiroshi
Published: November 2005

An optical waveguide which has a multi-quantum-well (MQW) structure as an active or core region of the conventional double-hetero (DH) waveguide is attractive because of its low optical transmission loss at the wavelength where it makes stimulated emission when current-injected. This property is confirmed by fabrication a segmented electrode MQW (SE-MQW) laser diode, where only a part of the stripe electrode is current injected and the rest is not injected. The absorption coefficient was measured to be as low as 190 cm-1 for a SE-MQW waveguide, which was in good agreement with the photo-excited results previously reported.
Homodyne and Heterodyne Problems in Measuring Spectral Width of Polarized Rayleigh Line Scattered by Nematic Liquid Crystals
Authors: Akiyama Ryuichi , Tomida Komei , Endo Yukio , Murooka Hirofumi , Fukuda Atsuo , Kuze Eiichi
Published: November 2005

To clarify the stray light effect in a polarized component which contains information about the splay viscosity coefficient, Rayleigh scattering from a nematic, MBBA, is observed at a small scattering angle α'=8° by a highly accurate microcomputer-based photon correlation spectrometer. By tilting a homeotropically aligned cell with respect to the incident light around the axis perpendicular to the scattering plane, the superposition of homodyne and heterodyne signals is confirmed at -3°≤φ'≤8°, where φ' is the azimuthal angle specifying the director. However, almost ideal homodyne detection is found to be possible unless φ'≈α'/2.
Properties of Zn3P2Thin Films Grown by Ionized-Cluster Beam Deposition
Authors: Suda Toshikazu , Kanno Tsuneo , Kurita Shoichi
Published: November 2005

Zinc phosphide (Zn3P2) thin films have been fabricated by ionized-cluster beam (ICB) deposition on glass substrates. Highly crystalline Zn3P2films are obtained with a strong preferred orientation along the c-axis by optimizing the acceleration voltage and substrate temperature. The Zn3P2films have extremely good stoichiometry compared with those by conventional vacuum evaporation: fluorescent X-ray spectroscopy indicates Zn3P2.05for the Zn3P2films deposited at an acceleration voltage of 2 kV and substrate temperature of 300°C. The absorption coefficient is deduced from the optical transmission and reflectivity data; the fundamental absorption edge is obtained as 1.55 eV at 300 K.
Novel Method for Measuring Intensity Distribution of Focused Ion Beams
Authors: Arimoto Hiroshi , Takamori Akira , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

We have developed a method for directly measuring the diameter of finely-focused ion beams from the response of the secondary electron emission that is obtained when the focused ion beam is scanned across the boundary of an AlGaAs/GaAs junction. Si and Be ion beams with diameters of less than 0.1 µm have been measured with an accuracy of 5% by this method. Thus, this technique is found useful for monitoring beam diameter during the maskless implantation process. Actually, this technique has been used for monitoring the diameters of Be and Si ion beams for the implantation of those beams into GaAs.
Self-Modulation of Nonlinear Ionization Wave Packets Excited in He Glow Discharges
Authors: Ohe Kazuyuki
Published: November 2005

Evolutions of envelope solitons of ionization wave packets with finite amplitude are observed in a positive column of He glow discharges. The wave packet excited by a high voltage pulse divides into two or three packets with propagation along the discharge tube. Evaluating the coefficients of the nonlinear Schrödinger equation by the wave dispersion and down-shifts of the frequency with the increase in wave amplitude, the divided wave packets can be regarded as envelope solitons.
Plasma-Hydrogenation Effects in Doped CVD Amorphous Silicon Films
Authors: Hasegawa Seiichi , Ando Daizo , Kurata Yoshihiro , Shimizu Tatsuo
Published: November 2005

The effects of plasma-hydrogenation on the electron spin resonance (ESR), electrical properties and optical band gap are investigated for phosphorus and boron doped CVD amorphous silicon films. For phosphorus doped films, the doping efficiency and photoconductivity are largely improved with hydrogenation. However, for boron doped films, a negative hydrogenation effect on doping efficiency is observed. The role that hydrogen plays in these properties, and the nature of ESR centers with g=2.013 and 2.0043 due to the valence- and conduction-band tail states, respectively, are discussed through the hydrogenation effects.
Plasma-Oxidized Tunnel Barrier of Nb/Nb Josephson Junctions with Copper Interlayer
Authors: Nakayama Akiyoshi , Okabe Yoichi , Sugano Takuo
Published: November 2005

Niobium/niobium Josephson tunnel junctions were fabricated using electron-beam evaporation of Nb films and rf-plasma oxidation. Niobium reacts easily with oxygen, resulting in a decrease in its transition temperature. In order to suppress this reaction between the tunnel barrier and the Nb counter-electrode, a thin layer of Cu was evaporated on the tunnel oxide before the Nb counter-electrode was deposited. The sub-gap current of Nb/Nb junctions with a Cu interlayer was found to be smaller than without the interlayer. Moreover, it was found that using a clean and stabilized plasma process in forming the tunnel barrier is useful in decreasing the sub-gap current of the Nb/Nb junctions.
Asymmetry in Output Power of InGaAsP/InP DFB Lasers
Authors: Akiba Shigeyuki , Utaka Katsuyuki , Sakai Kazuo , Matsushima Yuichi
Published: November 2005

The output powers from the two ends of a DFB region were compared. The power ratios and the external differential quantum efficiencies of the lowest-threshold modes were calculated in detail for an asymmetric end structure, one end being a cleaved facet and the other end being non-reflective. Power ratios of 2–5, depending on the corrugation phase at the cleaved facet, were predicted for
K

L=2–3. Such large ratios were actually estimated experimentally in InGaAsP/InP DFB lasers with a window region at one end. A larger output from a window region may be useful if the window region length is restricted, to about 10 µm or less in this case. The asymmetric output power in an FP-type DFB laser was also demonstrated.
Formation of Periodic Ripple Structures in Picosecond Pulsed Laser Annealing of Ion-Implanted Silicon
Authors: Kanemitsu Yoshihiko , Kuroda Hiroko , Shionoya Shigeo
Published: November 2005

Temporal changes in the self-reflectivity of a picosecond excitation pulse in laser annealing of ion-implanted silicon were measured, and the surface morphologies after annealing were studied. At intensities above the damage threshold, the reflected signal decreases, and simultaneously periodic ripple structures appear around the laser-induced damaged region. These ripple structures are formed by interference between a pulse wave originating as a result of scattering at the damaged point and propagating on the non-damaged surface, and the rear part of the incident pulse wave illuminating the non-damaged surface.
Scanning Electron Beam Annealing of P-Ion-Implanted Si(100) and (111) Substrates
Authors: Ishiwara Hiroshi , Suzuki Kunihiro
Published: November 2005

The crystalline quality and electrical properties of P-ion-implanted Si(100) and (111) substrates subjected to scanning electron beam annealing are presented. The electrical properties of the implanted layers were measured as functions of the electron beam power, the implantation dose and energy, and the substrate orientations. The properties were then compared with the crystalline quality of the layers, which was measured by Rutherford backscattering and channeling spectroscopy, and transmission electron microscopy. It was found that the electrical activity in Si(100) substrates is almost 100% at doses around 1×1015 cm-2, but that in Si(111) substrates, the implanted layer does not grow epitaxially up to the surface. Instead, part of the layer becomes polycrystalline in the same dose region. It was also found that a two-step process consisting of low-temperature furnace annealing and subsequent electron-beam annealing effectively activates implanted P atoms in Si(111) substrates without redistributing the atoms.
A Theoretical Investigation of the Collective Acceleration of Cluster Ions with Accelerated Potential Waves
Authors: Suzuki Hiroshi , Enjoji Hiroshi , Kawaguchi Motoichi , Noritake Toshiya
Published: November 2005

A theoretical treatment of the acceleration of cluster ions for additional heating of fusion plasma using the trapping effect in an accelerated potential wave is described. The conceptual design of the accelerator is the same as that by Enjoji,1,2) and the potential wave used is sinusoidal. For simplicity, collisions among cluster ions and the resulting breakups are neglected. The masses of the cluster ions are specified to range from 100 m
D to 1000 m
D (m
D: mass of a deuterium atom). Theoretical treatment is carried out only for the injection velocity which coincides with the phase velocity of the applied wave at the entrance of the accelerator. An equation describing the rate for successful acceleration of ions with a certain mass is deduced for the continuous injection of cluster ions. Computation for a typical mass distribution shows that more than 70% of the injected particles are effectively accelerated.
Dynamic Laser-Light Scattering Study on Bacterial Growth
Authors: Miike Hidetoshi , Hideshima Masao , Hashimoto Hajime , Ebina Yoshio
Published: November 2005

The motility changes in growing bacteria in a culture medium were observed with a dynamic light-scattering technique used to analyse the frequency spectrum of the scattered light intensity. Two typical enterobacteriaceae, E. coil and P. morganii, were examined, and the change in the velocity distribution of the bacteria with time was analysed using the observed spectrum. The distribution pattern was found to change from a Gaussian-type to a Saclay-type with time, and the mean speed of the bacteria had a maximum value at around the turning point of the growth curve.
Cryogenic Neutron Calorimeter for and ICF Test Facility
Authors: Tsuji Ryusuke , Ido Shunji
Published: November 2005

This paper proposes a new technique for measuring the neutron yield from ICF test facilities and other neutron facilities in situ. The technique employs the temperature increase by neutron heating of material cooled to below 4 K, where the specific heat decreases drastically. In materials (graphite, Be, B, Cu, U and Si) cooled to 2 K and placed 10 cm from a fusion pellet (1012 n/shot), the temperature increase is found to be 0.74 K, 0.77 K, 4.15 K, 0.17 K, 0.82 K and 2.05 K respectively. These temperature increases are ∼104∼5 times as large as those at room temperature and are measurable by a carbon resistance thermometer. The neutron yield can be calculated from the temperature increase of the materials.
Photoeffects in Polycrystalline TiO2 Electrodes
Authors: Yoon Ki Hyun , Yoon Sang Ok
Published: November 2005

TiO2 polycrystalline electrodes have been made by flame oxidation of Ti metal and a study of photo-electrochemical conversion with a polycrystalline TiO2 electrode shows the processes sensitive to applied voltage, oxidized TiO2 thickness and concentration in the PEC cell.
The anodic current starts at -0.8 V in 1N-NaOH solution, and the photocurrent appears at a wavelength around 420 nm. The photocurrent increases with light intensity and the emf of the cell drops a rate of 58.5 mV/pH.
VLS Growth Mechanism of Cd Crystals with Sn Impurities
Authors: Yumoto Hisami , Hasiguti Ryukiti R.
Published: November 2005

The Cd vapor pressure and the Cd–Sn liquid phase remaining on a spherical Cd primary crystal determine the final morphology of Cd crystals grown by the VLS (vapor-liquid-solid) mechanism with Sn impurities. The resulting crystals are pencil-shaped, whisker-shaped, or icosahedra with either the c or a growth axis.
Hydrogen Permeation through Nickel
Authors: Furuya Yoshio , Hashimoto Eiji , Kino Takao
Published: November 2005

The time dependence of the rates of permeation of hydrogen through annealed and as-rolled nickel foils was measured in the temperature ranges 120–430°C and 80–200°C, respectively. Annealed specimens exhibited permeabilities, diffusivities and solubilities that were in fairly good agreement with previous results, while the permeation characteristics of an as-rolled specimen differed from those of the annealed ones owing to the trapping of hydrogen at sites probably associated with vacancies. The trap binding energy was about 0.26 eV. Furthermore, anomalous permeation due to an oxide barrier was observed after specimens were kept under low vacuum for a long time. This anomaly exhibited a characteristic behavior around the Curie point.
RF-Induced Steps in the V-I characteristics of a Superconducting Closed Loop Formed form 2N-Josephson Junctions
Authors: Takanaka Kenji , Kobayashi Tadayuki , Yamashita Tsutomu
Published: November 2005

This paper reports a theoretical study of a superconducting closed loop consisting of a parallel connection of two linear series arrays of N-Jesephson junctions, exposed to a microwave field of frequency F. Constant-voltage steps in the current-voltage characteristics are found to appear at V
dc=2m
N
F Φ_0, where m is an integer and Φ_0 is the flux quantum, if the loop inductance is small.
Separation of the Elastic Silver Kα1 Component from Amorphous Scattering of X-Ray Silver Kα Radiation
Authors: Kodera Shiro , Ino Tadashi
Published: November 2005

The Compton and AgKα2 Component (λ=0.56380 Å) in amorphous scattering have been eliminated by the method of fluorescence excitation of Ru. Radiation scattered from a sample falls on a sheet of Ru (λ(K edge)=0.56051 Å). The fluorescence radiation, received in an Na-I scintillation counter placed near the Ru, is a close measure of the elastic scattering of AgKα1 radiation (λ=0.55941 Å) because most of the inelastic scattering and AgKα2 radiation is incapable of exciting fluorescence.
Photo-Induced ESR and Its Annealing Behavior in Melt-Quenched Ge–S Glasses
Authors: Kumagai Naoki , Shirafuji Junji , Inuishi Yoshio
Published: November 2005

Photo-induced ESR and its annealing behavior in melt-quenched GeS
x
(x=1.5, 0.8 and 2) glasses have been studied. Measurement of the effect of gamma-ray irradiation on the photo-induced ESR reveals the important role of quenched-in dangling bonds in the photo-enhancement of the ESR signal. The isothermal and isochronal annealing behavior of the photo-induced ESR in GeS
x
(x=1.5, 1.8 and 2) glasses can be explained in terms of a first-order reaction in which a Gaussian distribution of the activation energy is assumed.
Studies of Phase Transition and Molecular Motion in Homologous Series of Cholesteryl ω-Monohydrofluoroalkanoates by Dielectric Measurements
Authors: Yano Shinichi , Tsuruta Tadashi
Published: November 2005

The phase transition and molecular motion in a homologous series of cholesteryl ω-monohydrofluoroalkanoates [CHFA, C27H45OCO(CF2)
n
CF2H, n=1, 3, 5, 7] were studied by dielectric measurements. Two phase transitions were found near -53 and -18°C in the n=5 crystals, but both the n=3 and n=7 crystals show no phase transition in the crystal state. The crystals of the esters longer than n=1 did not show the successive phase transitions which exist in the n=1 crystals. One dielectric relaxation was observed in the lower temperature range for all the crystals, and this was not associated with the phase transitions. The phase transitions and the dielectric behavior of the relaxation are reflected faithfully in the crystal structure.
Optical Characterization of GaAs and GaP Laser-Annealed in High-Pressure Ar Atmosphere
Authors: Sato Katsuaki , Morita Masahiko , Sato Fumio
Published: November 2005

Pulsed laser annealing was carried out on ion-implanted GaAs and GaP crystals in Ar gas at pressures between 1 and 1000 bar. The laser-annealed specimens were characterized by optical methods such as reflectivity, absorption and photo-acoustic spectroscopy. These methods proved to be sensitive to microscopic crystalline defects and to be capable of characterizing the laser-annealed layer of III-V semiconductors.
Surface-Induced Nematic Ordering using SiO2 Grating
Authors: Sugimura Akihiko , Kawamura Takao
Published: November 2005

The orientational order parameter and elastic strain energy near a physically-treated surface are presented. Gratings with various pitches (0.5, 0.75, 1 and 2 µm) are fabricated on the cell substrate in order to investigate the surface-induced nematic (RO-CH 154) ordering. The orientational order parameters measured at the surface and in the bulk decrease with increase in the grating pitch and saturate at a pitch of 1 µm. We show that the liquid crystal molecules are uniformly aligned parallel to the grating grooves for an elastic stain energy higher than 10-7 J/m2.
Implantation Profiles of Low-Energy Helium in Silicon Carbide
Authors: Miyagawa Soji , Ato Yasuro , Miyagawa Yoshiko
Published: November 2005

The projected range profiles of helium implanted in silicon carbide were measured for energies between 1 keV and 20 keV using a method based on a combination of ion sputtering and gas release. The method is capable of producing helium depth profiles with a depth resolution of less than 100 Å, and a sensitivity to implantation fluences of 2×1016 ions/cm2 and below, where bubble formation is unlikely. The results were compared with theoretical predictions by Monte Carlo calculations, and good agreement was obtained by using values of the electronic stopping powers equal to 1.3 times the stopping constants given in the semiempirical tabulation by Northcliffe and Schilling. The effects of target temperature on the helium range profiles were also measured at 600°C, and the results were found to be associated with the grain-boundary diffusion of helium.
Pseudo-Line-Shaped Temperature Distribution Produced by Two-Dimensional Scanning with a Circular Gaussian Electron Beam
Authors: Yamada Masayoshi , Yamamoto Keiichi
Published: November 2005

The formalism for calculating the temperature distribution produced in a semi-infinite material by two-dimensional scanning with a circular gaussian electron beam, taking its penetration effect into account, has been derived using a Green's function analysis. The pseudo-line condition is examined for the sinusoidal scanning of practical interest, and a set of numerical calculation curves is presented. It is found that the pseudo-line-shaped temperature distribution is drastically changed from a concave to a convex profile by the increase in the oscillating width of the sinusoidal scanning. An approximate application of great technological interest, that of silicon on silicon dioxide, is also discussed.
Localized-State-Density Distribution in Post-Hydrogenated CVD Amorphous Silicon
Authors: Nakashita Toshio , Hirose Masataka , Osaka Yukio
Published: November 2005

Chemically-vapor-deposited amorphous Si films containing no bonded hydrogen were hydrogenated by hydrogen plasma annealing. The remarkable reduction of the localized state density in the mobility gap produced by the hydrogenation was confirmed quantitatively by the field-effect technique. The localized state density near the center of the mobility gap was reduced to less than 1×1018cm-3eV-1, and the widths of the tail states below the conduction band and above the valence band were also decreased by the hydrogenation. An energy band model involving an electron trapping level ∼0.12 eV below the conduction band and hole trapping levels ∼0.35 and ∼0.20 eV above the valence band is proposed, and the ∼1.25 eV- and ∼1.10 eV-luminescence peaks are explained in terms of the radiative transitions between these trapping states.
Geometrical Correction Factor for Semiconductor Resistivity Measurements by Four-Point Probe Method
Authors: Yamashita Masato , Agu Masahiro
Published: November 2005

Geometrical correction factors are derived for semiconductor resistivity measurements by the four-point probe method on rectangular parallelepipeds. The conformal transformation method leads to the same numerical values as that obtained from the solutions of Poisson's equation in the lower limit of the sample thickness. Some numerical results are given as a function of the width, length, and thickness of the rectangular parallelepiped, the probe separation, and the probe position.
Interdiffusion of Al and Ga in Si-Implanted GaAs–AlAs Superlattices
Authors: Hirayama Yoshiro , Horikoshi Yoshiji , Okamoto Hiroshi
Published: November 2005

Interdiffusion in GaAs–AlAs superlattices after Si implantation at 200 keV was studied under various annealing conditions. Interdiffusion of Al and Ga at the GaAs–AlAs interface was not observed before annealing, and compositional disordering due to interdiffusion was found to be controlled by changing the annealing temperature, annealing time, and ion dose. Interdiffusion at the interface followed electrical activation of implanted Si. The interdiffusion coefficients for Al and Ga were estimated to be (2∼5)×10-18 cm2/s and (1∼3)×10-17 cm2/s at annealing temperatures of 750° and 800°C, respectively, in the dose range 2×1013∼2×1014 cm-2. The interdiffusion coefficients were found to increase markedly above a dose of ∼2×1014 cm-2. The results of direct TEM imaging were in good agreement with the predictions from the evaluated interdiffusion coefficients.
Gamma-Ray-Induced Absorption Bands in Pure-Silica-Core Fibers
Authors: Nagasawa Kaya , Tanabe Manabu , Yahagi Kichinosuke
Published: November 2005

Radiation-induced optical absorption bands in pure synthetic silica-core fibers were studied. The effect of Cl contamination on the absorption change of the irradiated fibers in relation to the radiation resistance was examined, and it was deduced that low-Cl fibers have good radiation resistance even when they have a low OH content. The effect of the OH content on the radiation response in low-Cl fibers was thus investigated. The radiation-induced 630 nm band is enhanced in higher-OH-content silica-core fibers. The 660 nm and 760 nm bands were also observed in certain irradiated fibers. The former increases with dose up to 0.1∼2 kGy but decreases at higher doses. The mechanisms of the radiation-induced bands are discussed.
Electrode Resistance of Metal Hydride in Alkaline Aqueous Solution
Authors: Yayama Hideki , Kuroki Kouichi , Hirakawa Kazuyoshi , Tomokiyo Akihisa
Published: November 2005

The electrode resistance of metal hydride in constant-current electrolysis is investigated. It is found that the diffusion of hydrogen in the electrode is the rate-determining step in the reaction and is the dominant cause of the electrode resistance. The activity of the electrode, corresponding to the reaction rate, is determined by the effective surface area and the diffusion coefficient of hydrogen in the bulk of the electrode. Some parameters concerning the electrode kinetics are estimated. TiMn1.5 is an excellent electrode material for a secondary battery with high current and energy densities.
Measurement of the Time-Dependent Temperature Variation of Combustion MHD Plasma
Authors: Aoki Yoshiaki , Seidou Tadashi , Ohtomo Norio
Published: November 2005

Using a light-polarization line-reversal method, the temporal temperature fluctuation in a combustion MHD generator accompanied by a transient increase in the Joule heating was clearly observed as a time series over a long period of time of 2∼2000 µs. The response time of the method was found to be a few µs, and the method has proved to be an excellent time-resolved method for the direct measurement of time-dependent temperature fluctuations.
Variations in X-Ray Fluorescence from GaAs and Photocurrent in CdS due to Standing Waves of X-Rays
Authors: Annaka Shoichi , Takahashi Toshio , Kikuta Seishi
Published: November 2005

The intensities of the K-series fluorescence from GaAs and the photocurrent in CdS were measured during the dynamical diffraction of X-rays. Variations in the fluorescence during the 111 and 1̄1̄1̄ reflections and the photocurrent during the 110 reflection are explained by considering X-ray standing-wave fields in crystals. The effect of the standing waves on the fluorescence yield is emphasized when the fluorescence from layers near the surface is measured. The curve of the variation of the photocurrent in CdS is explained by considering the proper absorption coefficient of electrons in the crystal. A principle for the standing waves in the dynamical diffraction of X-rays is also given.
XPS Study on the Oxidation of InSe
Authors: Miyake Izumi , Tanpo Toyokazu , Tatsuyama Chiei
Published: November 2005

The initial stage of the reaction of oxygen with the surface of layered semiconductor InSe has been studied by XPS. The cleaved surface of InSe does not react with oxygen at room temperature. However, when subjected to Ar ion sputtering, the surface becomes In-rich, and can then be oxidized at room temperature. By heating a sample with a cleaved surface in the atmosphere, the intralayer bonding between Se and In atoms is severed by the formation of In-oxides. In both cases, first, In2O3+x
is formed at the surface due to the presence of In–O2 bonds. As oxidation proceeds, In2O3 grows under In2O3+x
. In2O3-x
is also observed in room-temperature oxidation. No evidence could be found for the presence of Se oxides on the surface under any oxidation conditions. It is found that a heterojunction cell of In2O3–InSe fabricated by the thermal oxidation of InSe exhibits the photovoltaic effect in the visible light region.
Heavy Ion Beam Probe for the Study of Plasma Confinement in Nagoya Bumpy Torus
Authors: Takasugi Keiichi , Iguchi Harukazu , Fujiwara Masami , Ikegami Hideo
Published: November 2005

The heavy ion beam probing system has been constructed for the study of plasma confinement in Nagoya Bumpy Torus (NBT-1/1M). Not only the plasma space potential but also the electron density multiplied by a function of the electron temperature n
f(T

e
) can be measured with good spatial resolution. The feedback controlled detection technique and the time resolved fast detection technique are used, depending on the operation mode. The effects of the hot electron beta and the potential on the beam orbit are analyzed. It was confirmed that these effects on the observation points are usually small, and that the hot electron beta can be estimated from the shifts of the primary beam orbits of many cords.
Structural Analysis and Expeimental Characteristics of High-Voltage Bipolar Transistors with Shallow Junctions
Authors: Sakurai Tetsuma , Ohno Terukazu
Published: November 2005

Presented are a structural analysis and experimental characteristics of high voltage bipolar transistors having shallow junctions formed in a dielectrically-isolated island. Structural analysis was carried out by means of computer-aided calculations for a bipolar transistor equipped with a field-plate of non-uniform oxide thickness, providing new insight into the nature of the junction-curvature-limited breakdown voltage. A 350 V bipolar transistor, as a result, with a shallow junction has been developed. Experimental high-voltage bipolar transistors exhibit characteristics suitable for use in a subscriber line interface circuit.
Single Crystals of CuxMo6Se8: Growth, Compositional Inhomogeneity and Superconducting Properties
Authors: Takei Humihiko , Takahashi Toshinori , Miura Tsuneo
Published: November 2005

Single crystals of Chevrel-type compounds Cu
x
Mo6Se8 (0≤x≤2.4) have been grown by the Bridgman method under a He pressure of 50∼100 atm, The content of copper x is observed to be gradually enriched as the crystal growth proceeded. The superconducting transition temperature T
c is determined as a function of x. The results are summarized into three regions; 6.0\lesssimT
c\lesssim6.5 for 0≤x\lesssim0.7, 6.0\lesssimT
c\lesssim5.0 for 0.7<x\lesssim2.0 and T
c<2.5 for x>2.0. The transition temperature width, Δ
T
c, increases with increasing x. The results of XPS indicate that no marked change occurrs with variation of x. The oxidation from Cu1+ to Cu2+ is observed by XPS on the surface of the pulverized crystals.
Electrical Conductivity Regulated by Transverse Electric Field in the Hot Electron Range in n-Type Silicon
Authors: Toyotomi Seizo
Published: November 2005

An attempt was made to control the electrical conductivity of n-type silicon by utilizing the anisotropic character of hot electrons. The I
<100>–V
<100> characteristics were measured in the presence of <010> electric fields at 77 K. The roles of the intervalley redistribution and the intravalley scattering of hot electrons in the observed results are discussed on the basis of an expression for the mobility in the <100> direction.
Microstructure and Magnetic Properties of Sputter-Deposited Ho–Co Alloy Thin Films with Perpendicular Magnetic Anisotropy
Authors: Suzuki Takao , Ichinose Hideki , Aoyagi Eiji
Published: November 2005

The structures of Ho19Co81 thin films fabricated by r.f. sputtering in Ar atmosphere are discussed. Electron microscopic observation shows that a columnar structure is developed along the direction of the film thickness. Each column is largely amorphous but contains locally-microcrystalline regions 30–50 Å in size. A high-resolution photograph of the lattice image indicates that these microcrystalline regions very likely consist of HoCo5 in a short range, and that the hexagonal c-axis is nearly directed along the thickness direction. It is suggested that the presence of such microcrystalline regions may need to be taken into account in discussing the origin of the observed perpendicular magnetic anisotropy in rare-earth transition metal amorphous films.
EPR Study on Cr2+ Distribution in LEC GaAs:Cr Wafers
Authors: Suemitsu Maki , Suzuki Yoshihiro , Miyamoto Nobuo
Published: November 2005

EPR measurements were made on two LEC-grown (100) GaAs:Cr wafers. For both samples, [Cr]=2 wt-ppm. The observed Cr2+ distributions showed inverted-U type (wafer A) and W-type (wafer B) variations. However, the leakage current (I
L) distributions for the respective wafers showed U-type and M-type variations, indicating an inverse correspondence between the I
L, and Cr2+ distributions. Although a consideration of the compensation mechanism suggests that the Cr2+ depletion at the periphery in wafer A is determined by the Cr distribution itself, atomic absorption measurements on the same wafer showed no such depletion of Cr. This result can be explained in terms of the nonuniform distribution of electrically-inactive Cr atoms in the wafer.
Static and Dynamic Characteristics of Electrooptic Bistable Devices
Authors: Okada Masakatsu
Published: November 2005

Comprehensive descriptions are given of the static and dynamic behaviors of electrooptic bistable devices. The static behaviors include the characteristics of optical output versus input and optical output versus phase retardation, and several modifications of operational characteristics. The transient and unstable responses, including the switching response, periodic self-pulsation, optical monostable pulse generation and chaotic behavior, are also discussed for electrooptic bistable devices with different feedback configurations.
Transmission Electron Microscopic Observation of Misfit Dislocation in InP/InGaAsP Double-Heterostructures
Authors: Ueda Osamu , Komiya Satoshi , Yamazaki Susumu , Kishi Yutaka , Umebu Itsuo , Kotani Tsuyoshi
Published: November 2005

The nature and behaviour of misfit dislocations induced in InP/InGaAsP double-heterostructures grown by liquid-phase epitaxy were studied by transmission electron microscopy.
Almost all of the misfit dislocations were of the 60° type, and pure edge dislocations and screw dislocations were very rarely generated. Other interactions between the misfit dislocations induced various types of reaction such as network formation, dissociation and pinning. The stacking fault energy in InP was determined from the distance between dissociated dislocations in the weak-beam image, as 55 erg/cm2.
Hypersonic Velocities and Submicrocrack Formation in Ductile Polymers under Uniaxial Tensile Stress
Authors: Shichijyo Shiro , Nishimura Kazuhiro , Shirouzu Shigenori , Matsushige Kazumi , Takemura Tetuo
Published: November 2005

Longitudinal hypersonic sound velocities in two kinds of ductile polymer, polycarbonate (PC) and polyethylene terephthalate (PET), were examined by Brillouin scattering. These two materials exhibited a decrease in hypersonic sound velocity (the softening phenomenon) when stress was applied, but the amount of softening as well as its angular dependence with respect to the stress direction were much smaller than those for a typical brittle polymer, poly (methyl methacrylate) (PMMA). Furthermore, a correlation between these acoustic properties and the formation of submicrocracks was demonstrated by small-angle X-ray scattering (SAXS) measurements. The difference in the anisotropies in the softening of sound velocity between ductile and brittle polymers is discussed from the viewpoint of the shape and density of the submicrocracks
Analysis of Anomalous Discharge Current in Low-Density Polyethylene
Authors: Kitani Isamu , Tsuji Yasumasa , Arii Kiyomitsu
Published: November 2005

An anomalous discharge current flowing in the same direction as the charging current was observed in a low-density polyethylene film with evaporated silver electrodes at room temperature (25°C) after the application of a very high field above 2×108 V/m.
The discharge transient current was computer-analyzed numerically by an explicit difference method. The anomalous current was attributed to the large amount of two types of injected space charge (electrons and holes) with ohmic electrodes, and not to one type of injected space charge (electrons or holes) with blocking electrodes.
Self-Scanning Photodiode Array as X-Ray Detector and Its Application to EXAFS
Authors: Taniguchi Kazuo , Yamaki Naohito , Ikeda Shigero
Published: November 2005

A commercial self-scanning photodiode array (SSPA) for visible light sensing has been tested as a position-sensitive detector for X-rays. The SSPA could be used as an X-ray detector with little radiation damage, and exhibited good positional sensitivity and good response to X-rays. This paper reports the structure, drive circuit, radiation damage and resolution of the SSPA, the rapid measurement of X-ray spectra, and its application of EXAFS for the structural study of metal foils and solutions.
Lifetime Evaluation of Denuded Zone Quality and Intrinsic Gettering Effect on Heavy Metals
Authors: Ikuta Kenji , Ohara Takahiko
Published: November 2005

Minority carrier lifetime is used in electrical evaluation of intrinsic gettering. Lifetime in the intrinsic gettered wafer denuded zone is reduced to a third that of the starting material. No defects are observed in the wafers, even by transmission electron microscopy. This suggests the possibility that oxygen-related, undetectable residual defects exist in the denuded zone. Heavy metal contamination by reactive ion etching degrades the lifetime three figures to 1 µs by inducing surface defects. Intrinsic gettering can recover more than two figures of lifetime by suppressing the defects that are to be induced by heavy metals. The gettering ability of a defect is found to be 160–800 metal atoms depending upon defect size. The bulk defect density needed for gettering various degrees of heavy metals is determined. This technique is valid for a wide range of heavy metal atoms to 1017 cm-3.
Epitaxial Growth of High-Purity GaAs by Low-Pressure MOCVD
Authors: Takagishi Shigenori , Mori Hideki
Published: November 2005

High-purity GaAs epitaxial layers were reproducibly obtained at operating pressures lower than conventional low-pressure MOCVD. The epitaxial layer grown at 17 Torr exhibited a high mobility of 105,000 cm2/V·sec at 77 K and a fine exciton structure in the low-temperature PL spectrum. The conductivity of epitaxial layers grown at 8 Torr changed from p-type to n-type as the [AsH3]/[TMG] ratio increased. PL spectra indicated that carbon is the dominant acceptor and that carbon concentration and fine exciton structure depend strongly upon the [AsH3]/[TMG] ratio.
Donor Levels in Si-Doped AlGaAs Grown by MBE
Authors: Watanabe Miyoko Oku , Morizuka Kouhei , Mashita Masao , Ashizawa Yasuo , Zohta Yasuhito
Published: November 2005

Donor levels of MBE-grown Si-doped Al
x
Ga1-x
As have been characterized by a combination of the C-V method and capacitance and current transient spectroscopy. Although most electrons are supplied by so-called DX centers in the AlAs mole fraction (x) range of 0.3∼0.7 in this material, it is found that a small amount of shallow donors are still present. The concentrations of the DX center and the shallow donor are determined in detail as a function of AlAs mole fraction and Si doping level. The activation energy obtained by the Hall effect measurement is discussed in association with these data.
Low Temperature Dielectric Properties of Phosphate Glasses Containing Nd2O3
Authors: Jinzaki Yoshinobu , Okuda Yuichi , Chan Moses H. W.
Published: November 2005

Measurements of capacitance of phosphate glasses containing Nd2O3at temperatures from 1 K to 10 mK are presented. The capacitance varied logarithmically with temperature having a minimum around 250 mK. However, such a dehavior completely disappeared in magnetic fields above 5 kOe. The magnetic impurity Nd2O3gives an important contribution to dielectric properties of phosphate glasses. This is the first result to show that a hydroxyl OH in phosphate glasses is in a state which is different from that in silicate glasses.
Effect of the Grating Phase at the Cleaved Facet on DFB Laser Properties
Authors: Matsuoka Takashi , Nagai Haruo , Noguchi Yoshio , Suzuki Yoshio , Kawaguchi Yoshihiro
Published: November 2005

The importance of the relative positions of the reflectors and grating in InP/InGaAsP DFB laser diodes in determining laser thresholds and oscillation wavelength is directly verified for the first time using a precisely controlled ion beam etching technique. Periodic variation in both the threshold current value and oscillation wavelength as a function of etching depth is observed, and the period closely coincides with one half the oscillation wavelength in the laser cavity.
Fusion Engine Cycle in Reactor System by Adiabatic Compression
Authors: Itoh Sanae-Inoue , Itoh Kimitaka
Published: November 2005

Cycle operation in magnetic confinement reactors is proposed in order to convert fusion energy directly to electromagnetic energy. By adiabatic compression, the fuel plasma is heated to exceed the ignition criterion. Thermal energy due to reactions is converted to electromagnetic energy through decompression. Decrease of the temperature closes the cycle. The energy conversion efficiency is studied. A large fraction of fusion energy can be directly converted.