bluuebunny/crossref_metadata_2025 huggingface dataset:
Threshold Voltage Behavior for WSi/AlxGa1-xAs/GaAs MIS-Like Heterostructure FET
Authors: Arai Kunihiro , Mizutani Takashi , Yanagawa Fumihiko
Published: November 2005

WSi/Al
x
Ga1-x
As/GaAs MIS-like heterostructure FET (MIS-HFET) is compared with HFET fabricated using the same MBE apparatus. Threshold voltage (V
T) variation through a wafer is much less for MIS-HFET (±0.05 V) than for the present HEMT (±0.15 V∼±0.4 V). In addition, threshold voltage shift as lowering the temperature from 300 K to 85 K is also much less for MIS-HFET (0.05 V) than for HMET (0.22 V). As it is simpler for MIS-HFET to obtain high V
T uniformity and small V
T dependence on temperature than for HEMT, MIS-HFET is believed to be attractive for LSI application.
Room Temperature CW Operation of GaSb/AlGaSb MQW Laser Diodes Grown by MBE
Authors: Ohmori Yutaka , Suzuki Yoshifumi , Okamoto Hiroshi
Published: November 2005

CW operation was achieved by a mesa-stripe (10 µm wide and 200 µm long) GaSb(12 nm)/Al0.35Ga0.65Sb(3 nm) modified multi-quantum-well (MQW, 6 wells) laser diode grown by molecular beam epitaxy (MBE) with threshold current I
th=145 mA at 14°C. Lasing wavelength was 1.662 µm at 9°C. Keys to this achievement were optimizations in (i) MBE growth condition, (ii) layer structure of the MQW wafer (introduction of a superlattice buffer layer and high barrier layers in MQW), and (iii) device fabrication processes. This is the first realization of room temperature cw operation among any type of laser diodes made from an Al-Ga-Sb material system.
Minimization of Residual Stress in SOI Films by Using AlN Interlaid Insulator
Authors: Ogura Atsushi , Egami Koji , Kimura Masakazu
Published: November 2005

It was found that residual stress in SOI film recrystallized by laser annealing depends on both substrates and interlaid insulator materials. For a stress free Si film, a thermal expansion coefficient of the underlaid material, comprising of a substrate and an interlaid insulator should be slightly larger than that of Si. AlN found to be a very effective interlaid insulator. In the structure of resolidified-Si/3 µm thick insulator/Si substrate, the residual stress in SOI film on AlN (5×109 dyn/cm2) was lower than that on SiO2 (7×109 dyn/cm2).
The Effect of Ultraviolet Irradiation on Electro and Electroless Platings of Nickel
Authors: Nakamichi Ichiro , Ishikawa Yutaka , Hirose Yoichi
Published: November 2005

Electro and electroless platings of nickel have been investigated during irradiation of ultraviolet (UV) light. Electroplating rate is enhanced by UV irradiation, while electroless plating on acrylic plate is suppressed considerably by such irradiation. These phenomena are not due to thermal effect but to photo-irradiation effect.
LEC Growth of InP Single Crystals Using Ceramics AlN Crucible
Authors: Kubota Eishi , Katsui Akinori
Published: November 2005

The liquid encapsulated Czochralski technique using a ceramics AlN crucible has been investigated for the growth of InP single crystals. High purity crystals, typically having a carrier concentration of 2.2×1015 cm-3 and a Hall mobility of 30100 cm2/(V·s) at 77 K for the first-to-freeze portion, are grown without serious contamination of electrically active impurities from the crucible. Impurity analyses of the grown crystals and the B2O3 encapsulants are carried out. The results are compared with those for the crystal grown from a pBN crucible.
High Contrast TEM Observation of Lattice Image of GaAs-Al0.28Ga0.72As Superlattice with [100] Electron Beam Incidence
Authors: Suzuki Yoshifumi , Okamoto Hiroshi
Published: November 2005

By using a high resolution transmission electron microscope (TEM) with electron beam incident along a [100] crystal axis, a cross-sectional lattice image exhibiting contrast high enough to distinguish constituent layers in superlattice was first observed on an MBE grown GaAs-Al
x
Ga1-x
As superlattice whose Al composition x was as small as 0.28, a range of great importance in practical device application. A theoretical considertion is given which supports that an observation along a [100] axis is more advantageous not only in obtaining high contrast but also in overcoming some of the illusive interference effects, than a conventional observation along a [110] crystal axis.
Characteristics of a Large Area High Sensitivity Particle Detector
Authors: Nakashima Yousuke , Ichimura Makoto , Miyoshi Syoichi
Published: November 2005

A large area and high sensitivity particle detector using a channeltron type electron-multiplier is designed and fabricated. The detector has a large metallic surface area from which secondary electrons are emitted due to the incident particles. The characteristics of the detector are measured by an alkali ion beam. It is confirmed that the effective detection region is about 13 times larger than that of the entrance aperture of the channeltron. This detector has been installed in a time-of-flight type neutral particle analyzer and operated well in the measurement of the neutral flux emitted from the GAMMA 10 plasma.
Current Injection Effects in a Nb/AlOx-Al/Nb/n-InSb Triode
Authors: Tamura Hirotaka , Hasuo Shinya , Yamaoka Toyoshi
Published: November 2005

A Nb/AlO
x
-Al/Nb/n-InSb triode has been fabricated and tested. The device is made on the (100) surface of undoped n-type InSb. The fabrication process is similar to that for Nb/Al-AlO
x
/Nb Josephson junctions. The transfer efficiency for injected electrons through a 240 nm thick Nb base layer was measured to be 1.6×10-4 at 4.2 K.
Fluxon Divider
Authors: Sakai Shigeki , Akoh Hiroshi , Hayakawa Hisao
Published: November 2005

A resistive-coupled fluxon divider consisting of Josephson transmission lines is designed and fabricated. Dynamic behavior of the divider is measured using two Josephson samplers connected to both output transmission lines, and successful operations are observed. It is also clarified that whether or not a fluxon signal can be transmitted to each output transmission line is determined mainly by the value of the bias current applied to each such line. Numerical simulations are made, and the results are in good agreement with the experimental ones.
Group III Impurity Doped Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering
Authors: Minami Tadatsugu , Sato Hirotoshi , Nanto Hidehito , Takata Shinzo
Published: November 2005

The detailed study of electrical properties in group III impurity doped ZnO thin films prepared by rf magnetron sputtering is described. The resistivity is lowered by doping of B, Al, Ga and In into ZnO films. The characteristic features of ZnO films doped with group III elements except for B are their high carrier concentration and low mobility. Variation of the mobility with the impurity content is roughly governed by the ionized impurity scattering. It is shown that the doped ZnO films exhibit the resistivity dependence on film thickness below 300 nm.
Water-Soluble Barrier Material for Three-Layer Resist Systems
Authors: Namatsu Hideo , Shibata Toshitaka
Published: November 2005

Water-soluble films for use as intermediate barrier material in three-layer resist systems are proposed. A water-soluble film containing MoO3, which is formed at a high rate, is found to be suitable for use as the bottom layer etch mask because of its high resistance to O2 RIE. By dipping the substrate in water after etching the bottom layer, the water-soluble film can be easily removed, without damaging the bottom layer or the substrate. The water-soluble film is successfully applied to a three-layer resist system for both e-beam and optical lithography.
Patterning of Conductive Polypyrrole in Polymer Film
Authors: Hikita Makoto , Niwa Osamu , Sugita Akio , Tamamura Toshiaki
Published: November 2005

The electrochemical polymerization of pyrrole on an insulating polymer coated electrode the surface of which was fabricated to have conductive patterns, alloys the formation of electrically conducting polypyrrole patterns in the polymer film. Without using a direct lithographic process, a polymer film with a highly anisotropic conductivity where the surface resistance is as low as 200 Ω in 30 µm pitch line patterns, can be obtained in a free standing form.
Visible-Light Injection-Electroluminescent a-SiC/p-i-n Diode
Authors: Kruangam Dusit , Endo Toshihito , Okamoto Wei , Hamakawa Yoshihiro
Published: November 2005

A new type of visible-light injection-electroluminescent a-SiC diode has been developed. The LED has the structure of p a-SiC/i a-SiC/n a-SiC. Visible white-green, yellowish-orange and red light emissions have been observed for the first time in these junctions at room temperature. It is demonstrated that emitting color can be controlled by choosing the optical band gap of the luminescent active i a-SiC layer. The brightness of the yellowish-orange emission was 0.13 cd/m2 with a forward injection current density of 200 mA/cm2 for 0.033 cm2 cell area.
Se Doping Mechanisms in MOCVD GaAs Layers
Authors: Asai Hiromitsu , Sugiura Hideo
Published: November 2005

A model of the Se incorporation mechanism into MOCVD GaAs layers is discussed in terms of the competitive surface adsorption process between Se and As atoms. According to the model, the doping level is determined by [H2Se]/[AsH3] but is independent of [TMG]. The validity of the model is experimentally confirmed from the dependence of the doping level on H2Se, AsH3, and TMG concentrations. In addition, the model explains why Se dopant atoms are not accumulated at the interface when growth is suspended.
Production of High Density Ion Beam by Magnetic Compression
Authors: Nakagawa Yoshiro , Enomoto Tamotsu
Published: November 2005

A charge neutralized intense pulsed ion beam (∼40 A/cm2, \gtrsim50 keV) was injected axially into the strong magnetic field (up to 1.8 T) and this long pulse (\gtrsim400 ns) proton beam was guided and compressed (2r=6.0 cm to 2r=2.0 cm) efficiently by the magnetic field. Maximum ion current density at the beam center reached to 250 A/cm2 (ion density; n
i ≃5 ×1012/cm3). The ion current density and diamagnetic signal of the beam increased with increasing the magnetic field.
Investigations of N-H and Si-N Bonding Configurations in Hydrogenated Amorphous Silicon Nitride Films by Infrared Absorption Spectroscopy
Authors: Narikawa Shiro , Kojima Yoshimi , Ehara Shaw
Published: November 2005

The infrared absorption spectra of hydrogenated amorphous silicon nitride (a-SiN:H) films have been measured. Two absorption bands for the NH2 bonding group appear at ∼3450 cm-1 and ∼1550 cm-1, which are assigned to the NH2 stretching mode and NH2 bending mode, respectively. Isochronal annealing measurements show that the NH2 bonding configuration has more excellent thermal stability than the NH bonding configuration. In addition, the change of the integrated absorption intensity of the Si-N asymmetric stretching mode is observed with increasing annealing temperature.
MOCVD Growth of ZnSxSe1-x Epitaxial Layers Lattice-Matched to GaAs Using Alkyls of Zn, S and Se
Authors: Mitsuhashi Hiroshi , Mitsuishi Iwao , Kukimoto Hiroshi
Published: November 2005

ZnS
x
Se1-x
epitaxial layers have been grown on GaAs (100) substrates by metalorganic chemical vapor deposition (MOCVD) using Zn-, S- and Se-alkyls. With this source combination, the premature reaction typically encountered in the conventional MOCVD of zinc chalcogenides using Zn-alkyls and H2S or H2Se can be eliminated. The composition of ZnS
x
Se1-x
is easily controlled by the transport rates of S- and Se-alkyls. High crystalline quality of lattice matched samples is evident from the surface morphology and the line width of double crystal X-ray diffraction.
Relaxation Oscillations in Anti-Reflection Coated Low Reflectivity Laser Diode
Authors: Li Kenneth K. , Yu Kit Lai
Published: November 2005

Solving the rate equations without spatial averaging reveals the existence of a relaxation resonance peak in the frequency spectrum of an anti-reflection coated low reflectivity laser diode. This peak occurs at >20 GHz which has not been reported previously. Such a diode may have potential applications in high frequency microwave transmission.
Photothermal Beam Deflection (PBD) Image of Certain GaAs Wafers
Authors: Sawada Tsuguo , Gohshi Yohichi , Watanabe Tomoharu , Furuya Keiichi
Published: November 2005

The photothermal beam deflection (PBD) technique utilizes a change of refractive index of the gas surrounding a sample, and a thermoelastic deformation on the sample surface induced by the heat generated as a result of the light absorption. The elastic property of the sample has been measured nondestructively and without contact using PBD. This technique was applied for the first time to the inspection of a dislocation existing in a GaAs semiconductor wafer.
TEM Observation of Microstructure in Sputtered Co-Cr Film
Authors: Maeda Yasushi , Hirono Shigeru , Asahi Masayoshi
Published: November 2005

TEM observation of the microstructure in a sputtered Co-18.1 at%Cr film with perpendicular magnetic anisotropy was conducted. The TEM thin foil samples were prepared by dipping them in hydrazine monohydrate solution and milling them with ion beams. It was found that the microstructure of each crystallite showed bright stripe-like features in fairly regular directional patterns, which seemed to reflect compositional inhomogeneity.
Explosive Crystallization in Amorphous Silicon Induced by Picosecond High-Power Laser Pulses
Authors: Kanemitsu Yoshihiko , Tanaka Yuichi , Kuroda Hiroto
Published: November 2005

Ring-shaped crystallization was observed in ion-implanted amorphous silicon by using picosecond extremely high-power laser pulses. A poly-crystalline region is formed circularly around the laser-induced damage region even at an oblique incidence. Additionally, ripple structures are formed concentrically, and the ripple spacing decreases with increasing distance from the spot center. The results are well understood with a picture that crystallization is caused explosively by laser-driven shock.
Improved Fabrication Method of the Microbridge Utilizing Step Edge
Authors: Nakanishi Masakazu , Uehara Gen , Hara Ko
Published: November 2005

A microbridge is regarded as an ideal application of a Josephson junction. A simple fabrication technology for a microbridge having a very short link was previously proposed. Such a link is fabricated by utilizing a step edge; such a microbridge is named the MUSE. This stands for a Microbridge Utilizing the Step Edge. Another fabrication method for improving the stability and reliability of a microbridge is discussed in this paper.
Diamagnetism of Carbon Fibers
Authors: Matsubara Keiko , Kawamura Kiyoshi , Tsuzuku Takuro
Published: November 2005

The diamagnetic susceptibilities of a polyacrylonitryle-based carbon fiber (PAN-CF) and benzene derived carbon fiber (BDF) stepwise heat-treated up to 3000°C were measured between liquid-nitrogen and room temperatures. Total susceptibility (χT) vs reciprocal temperature (1/T) plots for PAN-CF specimens heat-treated beyond 1300°C are entirely in accordance with McClure-Hickman's theory dealing with the transverse size effect on the orbital diamagnetism of π electrons in folded graphitic ribbons, while those of BDF are not for the specimens heat-treated above 2200°C. As the heat-treatment temperature is increased beyond 2200°C, the structure of BDF gradually becomes three-dimensional; finally, χT of a 3000°C-treated sample can be explained by a theory of Sharma, Johnson and McClure for singlecrystal graphite.
Misaligned Spherical-Mirror Waveguide Resonators
Authors: Hsieh Tai-Chiung , Hsu Ken-Yuh , Li Yajun
Published: November 2005

The effect of misaligning the spherical mirror of a hollow waveguide laser resonator on the diffraction loss is investigated on the assumption that the waveguide acts as an EH11 signel-mode filter. Theoretical and experimental results are obtained and compared by means of the formula for homogeneous line broadening.
Effects of Gas Flow in DC-Excited Standing-Wave Gas Lasers
Authors: Asami Shigeo
Published: November 2005

We examine how much the oscillation characteristics of DC-excited gas lasers are influenced by the flow of a laser medium. Expressions for the gain and phase constants of a laser medium, the output power, and the spot size of a laser beam are derived as functions of the frequency and the ratio of the drift velocity of the active atoms or molecules to the velocity due to thermal motion. Although the gain and phase constants and the output power are still symmetric (or antisymmetric) with respect to the center frequency (even with a gas flow), the derived expressions indicate some quantitative changes in those oscillation parameters with a gas flow. Xe, He-Ne, and CO2 lasers are treated as numerical examples.
Plasma-Induced Arc and Its Plasma Response in a Toroidal Device
Authors: Takamura Shuichi , Shen Yun , Aoyama Goro , Okuda Takayoshi
Published: November 2005

A plasma-induced bi-polar arc and its plasma response were studied in a tokamak configuration, and a drastic change in the plasma potential near the arcing metal rod was found. Cylindrically concentric equi-potential surfaces are formed around the cathode spot, and a small change in the plasma potential observed at the plasma-wall interface breaks an ambipolarity there, forming a current channel across the toroidal plasma between the cathode spot and the vacuum chamber.
Normal Electric Field Dependence of Electron Mobility in MOS Inversion Layer
Authors: Shirahata Masayoshi , Hamaguchi Chihiro
Published: November 2005

Short channel MOSFETs with a channel length of 0.38 µm were experimentally investigated and analyzed using a two-dimensional device simulation. FET characteristics can be explained well when the effect of the normal field on the electron mobility (Cooper-Nelson formulas) in the inversion layers is taken into account. The normal field dependence of the electron mobility is interpreted in terms of a two-dimensional quantization of the electrons.
Pattern Recognition of Charged Particles for the VENUS Central Drift Chamber
Authors: Nakagawa Yuji , Hirose Tachishige , Kanzaki Jun-ichi
Published: November 2005

We have been developing a pattern-recognition program based on a road method for the VENUS central drift chamber. A unique feature of our algorithm is that it makes use of a particular cell structure of the central drift chamber. We could, thus, construct an efficient pattern-recognition program by solving left-right ambiguities in an early stage of the track-finding processes. Using Monte-Carlo simulation for the detector response, we can now achieve for hadronic jet events at √s = 60 GeV a track-finding efficiency of 96%, which is quite stable against the noise and resolution of the drift chamber. A three-dimensional reconstruction efficiency of almost 100% has been obtained for e
+
e
-→µ+µ- events and 92% for hadronic jet events.
Tungsten Trioxide/Liquid Electrolyte Electrochromic Devices with Amorphous Iron Tungstate Counter Electrodes– Response Characteristics and Cell Reliability
Authors: Yamanaka Kazusuke
Published: November 2005

Tungsten trioxide electrochromic devices using amorphous iron tungstate-graphite mixtures as counter electrodes were investigasted with the aim of attaining high reliability in such devices. The display electrode was prepared by an improved process which preserves transparent conductive layers in direct contact with the electrolyte, preventing the latter from dissolving them. Spin-on-glass-coated soda-glass substrates were used to eliminate the cell degradation caused by Na diffusion from substrate glass into WO3 films. Iron tungstate-graphite counter electrodes typically have a large capacity of 100 mC/V·cm2, with the result that the counter electrode potential change during operation was very small. Cells could be operated at a constant voltage with preferable response and long cycle lives of over 107.
Double Twin Path Interferometer for Thin Film Thickness Measurement
Authors: Chitnis Vijay Trimbak , Uchida Yoshiyuki , Hane Kazuhiro , Yoneda Katsumi , Hattori Shuzo
Published: November 2005

A unique interferometer which can automatically measure the thickness of a film with a simultaneous reference level control is described. This is achieved by using a grating to split a laser beam into various orders. The interference between the diffracted components of the 0 and -1 orders is used to control the reference level and the interference between the diffracted components of there two orders gives a measurement of the film thickness. Theoretical calculations show a very good linearity and high precision. Aluminium films with thicknesses ranging from 700 to 3000 Å were measured with a precision of ±200 Å. Remedies for an improvement of the precision are discussed.
Measurements of Nyquist Noise Spectra in Passive Electric Circuits by Using a SQUID
Authors: Itoh Mineo , Mizusaki Takao , Ohmi Tetsuo , Motomura Masato , Hirai Akira
Published: November 2005

The Nyquist noise power spectra of various electric circuits have been measured by using a SQUID. From these measurements, we have demonstrated the applicability of the observed noise spectra to noise thermometry. The results of the noise measurements, especially in bulk metal rods, might be useful for establishing noise-free conditions for SQUID measuring systems.
Fabrication of NbN/Pb(In) Josephson Junctions with High Resistive Normal Layer Produced by Ar+ Ion Bombardment
Authors: Saito Yukinori , Suganomata Shinji
Published: November 2005

NbN/normal layer/Pb(In) Josephson junctions were fabricated by Ar+-ion bombardment. A thin normal layer of the order of ∼7 nm with a very high resistivity was produced in the near surface of an NbN film. This type S-N-S junction showed well-defined constant-voltage steps up to about 500 µV when microwave power was applied.
Hasegawa's Three Point Method for Determining Transient Time Constants
Authors: Steele J. Michael
Published: November 2005

In many physical contexts it is important to estimate the time constant for a transient which is represented by a curve with exponential decay. The three point method for estimating such constants is studied here with the aim of understanding the influence of measurement error. The three point method is found to depend delicately on the choice of the middle (or design) point, to have a small positive bias, and to have a large standard error relative to the measurement errors.
Preparation of a-Si:H/a-Si1-xCx:H Superlattices
Authors: Nishikawa Satoshi , Kakinuma Hiroaki , Watanabe Tsukasa , Nihei Kouji
Published: November 2005

Amorphous silicon/silicon carbide superlattices were prepared by a glow-discharge technique. To reduce cross contamination from the gas phase, the preparation condition was carefully examined. It was shown that a purge procedure before any further sublayer depositions is effective in reducing this contamination effect.
The Change of the Charge Fluctuation with Ag Doping in Amorphous As2S3
Authors: Matsuishi Kiyoto , Onari Seinosuke , Arai Toshihiro
Published: November 2005

Far-infrared absorption spectra of Ag-doped amorphous As2S3 were measured in the wavenumber region 7-30 cm-1 with a Lamellar-grating Fourier Transform Spectrometer and the effects of Ag doping on the spatial fluctuation of charges were estimated with the charge-fluctuation model. The contribution of Ag doping on the increase of the charge fluctuation was derived to be about 0.5e per one Ag atom. From correlation effects of the charge fluctuations, the presence of an intralayer correlation ranging over about 7 Å for amorphous As2S3 could be confirmed.
Proton Nuclear Magnetic Resonance Studies on Structural Changes Induced by Annealing of Hydrogenated Amorphous Silicon Films Prepared at High Deposition-Rate
Authors: Ueda Masato , Chayahara Akiyoshi , Imura Takeshi , Osaka Yukio , Kumeda Minoru , Shimizu Tatsuo
Published: November 2005

The annealing behavior of hydrogenated amorphous silicon films prepared at high deposition rates has been characterized by proton nuclear magnetic resonance measurements. A part of the SiH configuration located in the low hydrogen-density phase converts into an SiH2 configuration below the annealing temperature (T
a) of 400°C. With a further increase in T
a, the SiH2 configuration is transformed into the (SiH2)
n
configuration in the high hydrogen-density phase. From the variation of the full-widths at half maximum of the narrow and broad NMR lines by annealing, a difference in the network structures between as-deposited films prepared at high and low deposition rates is suggested.
MOCVD Growth of InP Using Plasma Pre-Cracking
Authors: Sakai Shiro , Yamamoto Shin-ichi , Umeno Masayoshi
Published: November 2005

Plasma cracking of PH3 has been successfully applied in growing InP by MOCVD at 2.6 Torr. Plasma effects are an increase in the growth rate, the reduction of surface roughness and an increase in the photoluminescence intensity. This technique is very useful in growing any III-V alloy semiconductor systems, especially for thin-film growth. This is because the growth pressure can be reduced without being affected by an imperfect decomposition of the source gases. The growth parameter dependence of the grown-layer characteristics are investigated in this paper.
Optische Messungen der Dichte der von Azetylen Gebildeten Rußteilchen
Authors: Tsuboi Takao , Kamei Masaaki , Kobayashi Katsuhiko , Ikuta Yoshitaka , Katoh Reiichi
Published: November 2005

The density of acetylene-soot was obtained by making measurements using light extinction at 3.392 µm with an infrared He-Ne laser. Acetylene-soot was produced behind a reflected shock wave using a “tailored”-interface shock tube. The obtained value was 0.9± 0.2 g/cm3 at temperatures from 1500 to 2000 K. This value agreed with the value of benzene-soot which was measured using the same optical system with a normal shock tube. The wavelength dependence of the emission intensities due to soot particles, produced behind the reflected wave, agreed well in the visible and infrared regions with that of grey-body radiation.
A Simple Model and Calculation of the Influence of Doping and Intrinsic Concentrations on the Interstitial-Substitutional Diffusion Mechanism: Application to Zn and Cd in InP
Authors: Kazmierski K. , Cremoux B. de
Published: November 2005

A simple model of diffusion involving the internal electric field and the presence of neutral effects was developed. The interstitial-substitutional mechanism has been found to be very sensitive to the carrier concentration in the substrate which controls the shape of the diffusion profile and accelerates or retards the diffusion process. The variations of the junction depth with substrate doping has been attributed to the equilibrium shift between interacting species rather than to the internal field. From a detailed analysis of the zinc and cadmium diffusion profiles in InP, the presence of neutrals and the interstitial charge state have been identified.
Study of Hot-Pressed Ba(Ca1/3Nb2/3)O3-PbZrO3-PbTiO3 Ceramics. II. Phase Transition
Authors: Yokosuka Masaru
Published: November 2005

Measurements of the dielectric constants, electromechanical coupling coefficients, elastic compliances, spontaneous polarization and linear thermal expansion as functions of the temperature were carried out for tetragonal compositions of xBa(Ca1/3Nb2/3)O3-(1-x)[Pb(Zr
y
Ti1-y
)O3]. Studies of the dielectric properties and crystal structures under a varying electric field were also made in connection with the phase transition. From these experimental studies, overall characteristics were found to resemble those of PLZT.
On the basis of a previously introduced model for PLZT, the nature of the phase change between paraelectric cubic and ferroelectric tetragonal phases is briefly discussed.
Effect of Thermal Etching on GaAs Substrate in Molecular Beam Epitaxy
Authors: Saito Junji , Ishikawa Tomonori , Nakamura Tomohiro , Nanbu Kazuo , Kondo Kazuo , Shibatomi Akihiro
Published: November 2005

Thermal etching of GaAs substrates prior to epitaxial growth by molecular beam epitaxy has been used to reduce carrier depletion at the substrate and epitaxial layer interface. The amount of carrier depletion between a Si-doped n-GaAs substrate and a Si-doped n-GaAs epitaxial film, measured by a C-V carrier profiling technique, was proved to decrease significantly with increased etched depth at a substrate temperature of 750°C. The origin of the carrier depletion is believed to be the carbon acceptor, from the results of C-V measurement and secondary ion mass spectrometory. Based on these results, thermal etching was successfully applied to semi-insulating GaAs substrates to improve mobility and sheet concentrations of two-dimensional electron gas in the selectively doped GaAs/N-Al0.3Ga0.7As heterostructures with very thin GaAs buffer layers (0.2 µm).
Electron Transport across a Semiconductor Heterojunction
Authors: Maeda Hajime
Published: November 2005

An electron-transport theory is presented for an isotype semiconductor heterojunction diode with energy-band and effective-mass discontinuities. During an interface electron transfer, the electron total energy and transverse momentum are assumed to be conserved. After the quantum-mechanical transmission coefficient is determined with a tight-binding connection of the electron wave functions, the boundary conditions for the momentum distribution function are obtained, assuming a conservation of electron flux.
These conditions are applied to quasi-Fermi energy formulation in an approximate way. Numerical examples in an Al
x
Ga1-x
As/GaAs junction indicate that due considerations concerning interface electron-transfer effects are necessary for the design and simulation of longitudinal-type heterojunction devices.
Multi-Current Peaks for a Voltage-Controlled Negative Resistance in Si p+-i-n+ Diodes with a Hole Injecting Gate
Authors: Okazaki Shyohei , Kurosu Tateki , Akiba Yukio , Choe Ilyong , Iida Masamori
Published: November 2005

A multi-current peaks for a voltage-controlled negative resistance has been realized in a silicon p+-i-n+ diode with a hole-injecting gate formed in the intrinsic region. These devices are fabricated by a planar technique. Two methods for the fabrication of such devices are proposed. In the first method, multigates are formed in the intrinsic region of a p+-i-n+ diode. In the second method, several p+-i-n+ diodes with a hole-injecting gate are formed in the same silicon substrate; these diodes are connected in a parallel configuration. Devices fabricated by both methods show multi-current peaks for a voltage-controlled negative resistance. A definite voltage-controlled negative resistance region was observed in a device fabricated by the second method.
Pyrolysis and Photolysis of Trimethylaluminum
Authors: Suzuki Nobumasa , Anayama Chikashi , Masu Kazuya , Tsubouchi Kazuo , Mikoshiba Nobuo
Published: November 2005

A vapor-phase decomposition mechanism for the trimethylaluminum(TMA) used in an Al CVD was investigated by infrared spectroscopy. In pyrolysis, the annihilation of TMA was a first-order reaction and a CH3 radical was generated. The activation energy of the annihilation was about 0.4 eV. The generation mechanism of CH4 from the intermediates was investigated quantitatively. It is suggested that carbon contamination can be reduced by using an H2 carrier gas since the CH3 radical which causes such contamination is changed into CH4 by hydrogenation. In photolysis, the annihilation of TMA is a first-order reaction and C2H6 is generated by the coupling of two CH3 groups. The reduction of carbon contamination is also suggested because the generation of a CH3 radical is suppressed by the generation of C2H6.
Generation of Fine-Particle Beams and Their Applications
Authors: Ichihashi Toshinari
Published: November 2005

A collimated beam of fine-particles (diameter, 5-100 nm) of metals, semimetals or oxides was generated by injecting smoke into a vacuum chamber in which the gas was evacuated by differential pumping. The speed of the particles in the beam was estimated to be about 120 m/s by measuring the deviation from a horizontal line due to gravity. A silver beam was bombarded with electrons and deflected by an electric field. Neutral as well as negatively and positively charged particles co-existed in the beam for bombarding energies between 50 to 160 V. The speed of charged particles was measured to be about 200 m/s by a time-of-flight measurement. A beam of gold or silicon was injected directly into the specimen stage of a TEM so that smoke particles could be studied without exposure to air. Particles in the beam were heated with radiation or coated with metal in the vacuum.
Electroluminescence of Europium Ion-Implanted Aluminum during Anodization
Authors: Katsuno Masakazu , Morisaki Shigeyoshi , Baba Nobuyoshi , Iwaki Masaya , Takahashi Katsuo
Published: November 2005

Europium-implanted aluminum shows an orange electroluminescence (EL) during anodization in a 0.1 M ammonium pentaborate solution. The emission spectra show that this EL can be ascribed to the 4f-electron transitions of Eu3+ in an Al2O3 films. The EL intensity shows a maximum at a forming voltage of 70 V. The EL mechanism can be related to anodization in an Eu-implanted aluminum surface layer.
TM-Mode Selective Filter Using a High Refractive Index Lossy Layer Cladded Optical Waveguide
Authors: Ohke Shigeaki , Cho Yoshio , Okabe Takahiro
Published: November 2005

This report describes a TM-mode selective filter with GaAlAs-optical waveguides for use in monolithic integrated optics. It has only a high refractive index lossy layer as a cladding layer. As the result of a computation of the eigenvalue equation for a comparatively simple structure, it was found that a TM-mode selective-filter action could be obtained through a proper choice of the material and thickness of the cladding layer.
L11-Type Ordered Phase in Cu-Pt-Pd Ternary Alloys
Authors: Nakahigashi Kiyotaka
Published: November 2005

The composition and temperature range of an L11-type superlattice formation in ternary alloy systems CuPt1-y
Pd
y
, PtCu1-y
Pd
y
and (CuPt)1-y
Pd
y
has been studied by X-ray diffractometry and differential thermal analysis. The L11-type ordered structure with a rhombohedral symmetry was observed over a composition range of 0≤y≤0.4, 0≤y≤0.5 and 0≤y≤0.29 in the CuPt1-y
Pd
y
, PtCu1-y
Pd
y
and (CuPt)1-y
Pd
y
, respectively. The ordered structure with a negligible rhombohedral distortion was observed in the range PtCu1-y
Pd
y
(0.3≤y≤0.5) and (CuPt)1-y
Pd
y
(0.25≤y≤0.29).
The transition temperature from the L11-phase to a disordered Al-phase has a maximum value of 1080 K at the common terminal alloy CuPt and decreases nearly monotonically with increasing Pd content for all the alloy systems.
The Growth of Single Crystal of 3C-SiC on the Si Substrate by the MBE Method Using Multi Electron Beam Heating
Authors: Kaneda Shigeo , Sakamoto Yoshiki , Nishi Chikara , Kanaya Masatoshi , Hannai Sei-ichi
Published: November 2005

The growth of a single crystal of 3C-SiC on a Si substrate by the MBE method has been performed. A single-crystal film can be grown at a substrate temperature T
sub=1150°C. This temperature is relatively low compared to that used in other methods.
The diffused Si from a substrate plays an important part in the crystal growth of SiC, especially for a very thin film. The individual intensity of Si and C molecular beams (J
Si and J
C) and their intensity ratio J
Si/J
C should be selected with suitable values in accordance with the film thickness, considering the growth condition of the MBE method.
Computer Simulation of Dynamic Magnetic Bubble Collapse
Authors: Fujita Enji , Saegusa Yasuhide , Konishi Susumu
Published: November 2005

A computer simulation of magnetic domain wall motion was performed in order to study the dynamic bubble-collapse process under a wide range of drive fields. An unichiral bubble with a circular symmetry in a garnet film was assumed for simplifying the computation. The instantaneous bubble radius, horizontal Bloch line propagation, and wall overshoot effect were studied as well as the time-averaged wall velocity during the collapsing process. The time-averaged velocity of the bubble wall was compared with the results of the simulated velocity of a plane wall and the velocity measured in the dynamic bubble collapse experiment. There was a fair agreement among these velocities, but a slight difference in saturation velocity between bubble wall and plane wall was found. It originated from a difference in the surface stray in-plane field for these two geometries.
High-Pressure Brillouin Scattering Cell with Crystal Rotation Axis
Authors: Hikita Tomoyuki , Kaneko Hiroshi , Shibata Hajime , Ikeda Takuro
Published: November 2005

A high-pressure optical cell with four windows and a manipulating rod for crystal rotation was designed and constructed from SNCM-8 steel. Brillouin scattering on a cylindrical NH4Cl single crystal was performed as a function of the crystal orientation angle. The angular dependence of the Brillouin shift and linewidth was measured both at 22.5°C, 0.1 MPa and -11.4°C, 0.21 GPa. The spacious sample chamber permitted the installation of optical components, enabling us to perform small-angle scattering experiments using this optical cell.
Low-Pressure OMVPE of GaAs Using Triethylgallium
Authors: Kimura Kōzō , Takagishi Shigenori , Horiguchi Seishi , Kamon Koichi , Mihara Minoru , Ishii Makoto
Published: November 2005

Using triethylgallium and arsine, undoped GaAs layers have been grown by organometallic vapor phase epitaxy at pressures between 0.1 and 20 Torr. At constant flow rates, the growth rate changes with growth pressure, reaching a maximum at about 3 Torr. All grown layers are n-type with carrier concentrations of 1-3×1015 cm-3. The carrier concentration and mobility change with pressure, but are independent of the V/III ratio. The mobility data and low-temperature (4.2 K) photoluminescence indicate that carbon incorporation becomes important at pressures below about 1 Torr.
Determination of the Energy Spectrum of the Primary Beam in Energy-Dispersive X-Ray Diffractometry
Authors: Nishikawa Keiko , Ishizawa Keiko , Kodera Yasuto , Iijima Takao
Published: November 2005

The energy spectrum of white X-rays has been determined by the use of the scattering intensities from air and argon gas as references. It has been found that the spectra obtained from the gases are in good agreement with each other. However, they slightly, but significantly, differ from values obtained from direct measurements.
An Improved Technique for Fabricating High Quantum Efficiency Ridge Waveguide AlGaAs/GaAs Quantum Well Lasers
Authors: Sanada Tatsuyuki , Kuno Masaaki , Wada Osamu
Published: November 2005

A technique has been developed for improving the quantum efficiency and the temperature stability of ridge waveguide AlGaAs/GaAs quantum well lasers. Excellent lasing characteristics, including a differential quantum efficiency of 75%, have been achieved in graded-index waveguide separate-confinement heterostructure single quantum well lasers fabricated by this technique.
Influence of In Atoms on the Shape of Dislocation Etch Pits in LEC In-Doped GaAs Crystals
Authors: Ono Haruhiko , Matsui Junji
Published: November 2005

The shapes of dislocation etch pits formed by molten KOH on {001} LEC GaAs crystal wafers doped with various degrees of In content were investigated. The pit shape was found to change depending on the amount of the doped In. The geometrical relation between the pit shapes and the direction of the composed pit walls is discussed. The formation mechanism of each wall is examined microscopically regarding the explanation of the pit-shape variation. The pit-shape variation is interpreted to be due to an increase in the etch rate in only the Ga{111} planes; this is caused by the In atoms substituting the Ga atoms.
Growth Defects and Lattice Strains in LEC-Grown Single Crystals of InAsP
Authors: Minato Ichiro , Hashizume Hiroo , Watanabe Hisao , Matsui Junji
Published: November 2005

Defect structures and lattice strains in LEC-grown bulk single crystals of InAs
x
P1-x
(x=0.1∼0.3) have been characterized by X-ray diffraction topography using synchrotron and classical sources. A crystal ingot with a [1̄1̄1̄] growth axis consists of a relatively perfect center core surrounded by a less perfect outer region. While the core involves striations and dislocations at all growth levels, the outer region undergoes extended slips in the bottom half of the ingot. The lattice parameter increases at a nearly constant rate toward the ingot tail, with a characteristic expansion at the core center, both being ascribable to a non-uniform arsenic distribution. The observed lattice bending in the core part demonstrates the considerable internal stress present in the crystal.
Silicon Nitride Films Prepared by Plasma-Enhanced Chemical Vapour Deposition (PECVD) of SiH4/NH3/N2 Mixtures: Some Physical Properties
Authors: Ling C. H. , Kwok C. Y. , Prasad K.
Published: November 2005

Experimental data are presented on the effects of varying deposition parameters of SiH4/NH3 gas flow ratio, rf power, deposition pressure and substrate temperature, on the deposition rate, refractive index, hydrogen content and etch rates of PECVD silicon nitride films. BHF etch rate in these films are generally high and this is shown to be associated with the high hydrogen content. N-H and Si-H bond concentrations are measured in the range 1-4×1022 cm-3. The substrate temperature dependence of the etch rate exhibits a maximum for films deposited at 150°C. The behaviour is attributed to the incorporation of both hydrogen and oxygen, the effects on the etch rate of which are suggested to act in opposing directions.
Electrical and ESR Studies on Polythiophene by Radiation-Induced Doping Effect
Authors: Hayashi Shigenori , Takeda Shinji , Kaneto Keiichi , Yoshino Katsumi , Matsuyama Tomochika
Published: November 2005

The relation between electrical conductivity and ESR characteristics in polythiophene upon doping has been studied in-situ by utilizing the radiation-induced doping effect. By irradiation under an SF6 atmosphere, the electrical conductivity remarkably increases accompanied by distinct changes in the optical and magnetic properties. It has clearly been observed that a new narrower ESR component (ΔH
pp=c
a. 1 G) with a smaller g-value emerges and grows with increasing irradiation dose. These results indicate that the carrier species for dilute doping levels are polarons.
Analytical Investigation of Plasma and Electrode Potentials in a Diode Type RF Discharge
Authors: Suzuki Keizo , Ninomiya Ken , Nishimatsu Shigeru , Jr. J. W. Thoman , Steinfeld J. I.
Published: November 2005

Electrical potentials of a plasma and both electrodes in a diode type RF discharge are analytically obtained under the assumptions of quasi-static electric fields in an ion sheath, low gas pressure, charge neutrality of the plasma, and η≪1 (η is the ratio of electrode areas). The dependence of dV
pD/dU
D (V
pD and U
D are the DC part of the plasma potential and the potential difference between the plasma and the RF power electrode, respectively) on η is, then, compared with experimental results. We find the following conclusions: 1. The plasma potential does not necessarily have a simple harmonic form, even if the supplied RF power has that form. 2. The DC parts of the plasma potential and the RF power electrode potential change depending on the waveform of the supplied RF power, even if the RF amplitude and η are kept constant. 3. -dV
pD/dU
D depends quadratically on η, with a proportionality constant K which depends on the waveform of the supplied RF power.
Positional Instabilities in an Iron-Cored Tokamak
Authors: Nakamura Yukiharu
Published: November 2005

Including an unfavourable destabilizing effect due to an iron-core transformer, the positional instabilities were investigated for a horizontal expansion and vertical displacement of the tokamak plasma loop. The strong interaction of a current-carrying plasma loop with an image field as a result of the iron-core magnetization produces a considerable attractive force on the plasma loop towards the iron core. It is shown that the stability condition has a large dependence on the equilibrium position of the toroidal plasma and such parameters as the kinetic pressure of the plasma. It is also pointed out that the destabilizing effect due to an iron core restricts the stability margin against positional instabilities within narrow limits in most of the iron-cored tokamaks.
Pressure Effects on the Carrier Mobility in Polycarbonate Doped with Pyrazolines
Authors: Tsubakihara Shinsuke , Shichijyo Shiro , Taki Seiji , Matsushige Kazumi , Takemura Tetuo
Published: November 2005

Pressure effects on photoconductive process in polymer films of polycarbonate doped with pyrazolines were investigated up to 200 MPa and at different temperatures. With increasing applied pressure, the total amount of induced hole carriers increased substantially, while the drift mobility showed a slight negative pressure dependence. Possible reasons are discussed.
Extended Appearance Potential Fine Structure Analysis of Chromium
Authors: Konishi Ryōsuke , Tanigawa Hideyuki , Sasakura Hiroshi
Published: November 2005

The EAPFS (Extended Appearance Potential Fine Sructure) of chromium was observed. We obtained a nearest-neighbor atomic spacing of 2.53±0.1 Å(l=0), 2.54±0.1 Å(l=1) and 2.54±0.1 Å(l=2), respectively, by correcting the phase shift which was dependent on the final state of angular momentum l. These values are in good agreement with that for bulk values (2.50 Å).
Interface Stress at ZnSe/GaAs:Cr Heterostructure
Authors: Fujiwara Yasufumi , Shirakata Sho , Nishino Taneo , Hamakawa Yoshihiro , Fujita Shigeo
Published: November 2005

The interface stress at ZnSe/GaAs:Cr heterostructures grown by OMVPE has been investigated by measuring the Cr-related zero-phonon photoluminescence lines at 0.839 eV from the GaAs substrates. Based on analyses regarding the energy-shift and splitting of the luminescence lines, it has been found that a compressive biaxial stress exists in the substrate sides of these heterostructures; this is inconsistent with the stresses predicted for a lattice mismatch between the ZnSe epitaxial layer and the GaAs substrate. The interface stress at ZnSe/GaAs:Cr heterostructures grown by MBE were also investigated and the results are similar to those for OMVPE-grown heterostructures.
Room-Temperature Annealing Effects on Radiation-Induced Defects in InP Crystals and Solar Cells
Authors: Yamaguchi Masafumi , Itoh Yoshio , Ando Koushi , Yamamoto Akio
Published: November 2005

Remarkable defect annealing in both p-type and n-type InP following 1-MeV electron irradiation has been observed at room temperature, resulting in the recovery of InP solar cell properties. The room-temperature annealing characteristics of radiation-induced defects in InP were studied by measuring InP solar cell photovoltaic properties in conjunction with deep-level transient spectroscopy. The recovery of InP solar cell radiation damage is found to be due mainly to the room-temperature annihilation of radiation-induced recombination centers such as an H4 trap (Ev+0.37 eV) in p-InP. Moreover, the room-temperature annealing rate of radiation-induced defects in InP was found to be proportional to the 2/3 power of the carrier concentration. Additionally, a model has been considered in which point defects diffuse to sinks through impurities so as to annihilate and bind with impurities, thus forming point defect-impurity complexes.
Dependence of Prebreakdown Currents in Vacuum on Anode Oxidation Conditions
Authors: Suzuki Kenji , Kobayashi Shinichi
Published: November 2005

A description is given of how anode surface conditions produced changes in the vacuum prebreakdown current characteristics. Surfaces were processed by Ar-ion etching or oxidation. Electrode materials used were Cu and Al. Changes in the prebreakdown current levels during high-voltage application depended upon a combination of the electrode materials and their surface-processing methods. For oxidized Cu, the levels increased with a continuous high-voltage application time; for oxidized Al, the levels decreased. A surface analysis using X-ray photo-electron spectroscopy showed that oxides on these electrodes were desorbed by electron impact. The difference in the prebreakdown characteristics between Cu and Al is discussed from the viewpoint of the evaporation properties of oxides.