bluuebunny/crossref_metadata_2025 huggingface dataset:
New Quaternary Semiconductor Material Pb1-xCdxS1-ySey for Lattice-Matched Heterostructure Lasers with Emission Wavelength around 3 µm
Authors: Koguchi Nobuyuki , Kiyosawa Teruo , Takahashi Satoshi
Published: February 2005

The energy gap and the refractive index of a new quaternary semiconducting material, Pb1-x
Cd
x
S1-y
Se
y
, are determined experimentally. The compositional and temperature dependence of the energy gap of this material is E(x, y, T)=4.05x-0.141y-7.37x
2-0.00904y
2+0.115x
y+0.267+(4×10-4+2.65×10-7
T
2)1/2 (eV). The refractive index is n(x, y)=4.20-6.20x+0.483y+9.89x
2+0.106y
2+1.98x
y for the wavelength of 3.08 µm at room temperature. It becomes evident that the quaternary solid solution is a suitable material lattice-matched to PbS for the confinement layers of double-heterostructure lasers.
p-Si/n-CdS Heterojunction Solar Cells
Authors: Hayashi Toshiya , Nishikura Takehiro , Nishimura Kazuhiro , Ema Yoshinori
Published: February 2005

p-Si/n-CdS heterojunction solar cells having CdS windows were fabricated by evaporating double layers of n-CdS films (n+-CdS layer on n-CdS layer) on p-Si single-crystal wafer. The electric and photoelectric characteristics were measured and discussed. Various preparation parameters affecting the cell characteristics were discussed and the best condition for preparation of cells was found. Open-circuit voltage, short-circuit current and conversion efficiency measured under sunlight of input power intensity of 45 mW cm-2 ware 510 mV, 15mA cm-2 and 11.3%, respectively.
A New Process with the Promise of High Jc in Oxide Superconductors
Authors: Murakami Masato , Morita Mitsuru , Doi Kenji , Miyamoto Katsuyoshi
Published: February 2005

We report a new process which promises high critical current density in oxide superconductors. The process consists of three stages. Firstly a YBa2Cu3O
x
sample is rapidly heated and quenched from the Y2O3 plus liquid region. Subsequently the quenched sample is reheated to the Y2BaCuO5 plus liquid region, and then slowly cooled with a temperature gradient in flowing oxygen. The process enables us to grow a superconducting phase unidirectionally and to suppress the second phase intrusion, leading to the production of well textured YBa2Cu3O
x
which yields a high J
c value in the presence of magnetic fields. It is also found that Bean's critical state is realized in such high J
c samples.
Interaction between Combustion and Shock Waves
Authors: Terao Kunio , Inagaki Takeyuki
Published: February 2005

The pressure variations and the ionization of the gas behind a flame front propagating in a stoichionietric propane-air mixture through a plexiglass tube were measured by a piezoelectric pressure transducer and double-probe method, when shock waves produced by means of a shock tube propagated in the same plexiglass tube and collided with the flame. A remarkably high pressure increase and stimulation of ionization behind the flame front under the interaction with the shock waves were observed, and it was found that their values depended on the strength of the incident shock and the position of the shock front in relation to the flame front. These results are attributed to some exothermic reactions which follow the main normal combustion and produce detonation waves in the flame.
The Concept of a Sub-Prompt-Critical Nuclear Reactor and Its Applications to the Solution of Safety-Related Neutronic Problems in Reactor Kinetics
Authors: Das S.
Published: February 2005

The concept of a sub-prompt-critical nuclear reactor has been used to investigate a variety of neutron kinetics problems in reactor assemblies. Results of reactor response calculations (power, instantaneous period) and reactivity computations obtained using the present model are found to be in agreement with results obtained from the exact kinetics method to within 3 percent. Analytic expressions for the accident energy released in a controlled nuclear power excursion have been derived and their physical significances discussed. It is shown that if the energy released in the shut-down state is to be kept small, the first few dollars of reactivity should be removed as fast as possible and that it is adequate if the shut-down reactivity margin is kept within about 10 dollars. Application of the model to an earlier proposed pulsed fast reactor shows that its fictitious delayed neutron fraction lies between 35 and 45 pcm and its sensitivity between 4 and 6.
Study of Imploding Plasma Motion in a Gas-Puff Z-Pinch Plasma as an X-Ray Lithography Source
Authors: Tanaka Makoto , Kawata Hiroaki , Murata Kenji
Published: February 2005

Imploding plasma motion in a gas-puff Z-pinch plasma is studied using both the one-dimensional snowplow model and the energy balance theory. It is shown through use of the energy balance theory that the final plasma radius varies with load conditions, and that the implosion time under the optimum experimental condition agrees with the time yielding the maximum current. The maximum efficiency increases with a decrease in the initial width of an annular gas column, parasitic resistances and parasitic inductances. The use of a large-capacitor bank increases the pinched plasma energy, but decreases the efficiency. We also propose a simple method to estimate the compression enhancement effect by radiation energy losses. Finally, we discuss the optimum experimental condition of this type of X-ray generator for X-ray lithography.
Thermal Analysis of Phase Transformation in Metastable Au–Ge Films
Authors: Kikitsu Akira , Ikegawa Sumio , Komatsu Shuichi , Arai Shinji
Published: February 2005

Thermal analysis was performed on the phase transformation phenomena in sputtered Au–Ge films. The phase transformation from the metastable γ or β phase to the stable α+Ge phase was detected by a reflectance change occuring with temperature or time. Two types of analyzing methods were applied, one employing the Kissinger equation1,2) under an increasing temperature condition (nonisothermal analysis), and the other employing the Johnson-Mehl-Avrami equation3) under an isothermal condition (isothermal analysis). It was estimated that 63.2% of the metastable phase in Au–Ge films would decompose into a stable phase within 2000 days at room temperature. This estimation was compared with the experimental results obtained for aged samples, and it was concluded that the isothermal analysis was useful for the life estimation of metastable phases in thin films.
A Compact Low Voltage Flash X-Ray Tube
Authors: Wong C. S. , Lee S. , Ono C. X. , Chin O. H.
Published: February 2005

In this paper we describe the construction of a compact, low voltage flash X-ray tube. The device is powered by a small 25 kV, 3300 pF capacitor. Its design is of the vacuum spark configuration with a hollow cathode. The discharge is triggered by a low energy spark behind the hollow cathode; and the triggering spark is also powered by the main capacitor discharge. A 12 kΩ ballast resistor is connected to this auxiliary spark circuit to limit its current. The flash X-ray tube has been operated in air at pressures ranging from 10-1 to 10-4 mbar. At a charging voltage of 25 kV, the flash X-ray tube is able to produce X-ray pulses of several kilowatts in power.
Surface Migration of Ga and Al Atoms on (100) GaAs and AlAs during Migration-Enhanced Epitaxy
Authors: Horikoshi Yoshiji , Yamaguchi Hiroshi , Kawashima Minoru
Published: February 2005

Adsorption and migration characteristics of Ga and Al atoms on the GaAs and AlAs (100) surfaces are investigated using reflection high-energy electron diffraction along the alternate deposition of Ga or Al and As4 on the growing surface. Different characteristics are observed for Ga atoms deposited on a GaAs surface and for Al atoms deposited on an AlAs surface. Excess Ga deposition to the GaAs surface produces Ga clusters or droplets on the first Ga layer. They are dissolved very quickly after As4 deposition to form flat GaAs layers when the number of Ga atoms is closely equal to twice or three times the surface site number. This is not true, however, for Al deposition on AlAs. Different characteristics are also found for Ga and Al atoms deposited on the As-stable GaAs surface. All these results are interpreted in terms of different migration velocities of Ga and Al atoms.
Electron Spin Resonance of Oxygen-Nitrogen Complex in Silicon
Authors: Hara Akito , Fukuda Tetsuo , Miyabo Toru , Hirai Iesada
Published: February 2005

We observed the electron spin resonance of oxygen-nitrogen complexes (ONCs) and found that they have C2V symmetry. Although they contain nitrogen, hyperfine interaction (hf) with nitrogen cannot be clearly observed. These characters of ONCs resemble thermal donors (TDs) very closely.
A Monte Carlo Simulation of Secondary Electron Trajectories in a Specimen
Authors: Kotera Masatoshi , Kishida Takenobu
Published: February 2005

The secondary electron generation and the electron cascades are simulated by a Monte Carlo calculation along the incident primary electron trajectories in a specimen. The calculated energy distribution of the emitted slow electrons from the specimen surface is in good agreement with the experimental results and other calculated results.
High-Angle Double-Crystal X-Ray Diffractometry (HADOX): Combination with a Sealed-Tube X-Ray Source
Authors: Irie Kazutaka , Koshiji Naohiro , Okazaki Atsushi
Published: February 2005

A new arrangement of goniometers has been introduced to a HADOX diffractometer for measuring a change in the lattice constant with a high degree of accuracy. The distance between the X-ray source and the first crystal has been shortened by a factor of five. This gives a remarkable gain in diffracted X-ray intensities without reducing the accuracy, and makes it practicable to couple HADOX with a sealed-tube type of source. Also introduced is a new program for temperature control which is suitable for varying specimen temperatures near phase transitions. The performance of the diffractometer is examined for silicon 444 diffraction with CuKα1.
Local Fluctuation of Alloy Composition in InGaAsP/GaAs LPE Layers
Authors: Kato Takamasa , Matsumoto Takashi , Ishida Tetsuro
Published: February 2005

The cathodoluminescence (CL) of InGaP and InGaAsP layers grown on GaAs substrates has been studied. The band-to-band CL peak energy varied around naturally formed facets. The alloy composition determined from the X-ray microanalysis also changed around these regions. It was found that the difference in the distribution coefficients of constituent elements brought about this local fluctuation.
Growth and Superconductivity of a New Ternary Intermetallic Compound, Ta5Ga2Sn
Authors: Shishido Toetsu , Ye Jinhua , Toyota Naoki , Ukei Kazutoshi , Sasaki Takahiko , Horiuchi Hiroyuki , Fukuda Tsuguo
Published: February 2005

A new ternary intermetallic compound, Ta5Ga2Sn, has been synthesized by the self-flux method using molten tin as a solvent. The crystal structure is tetragonal (space group D4h
18/I4 mcm). The lattice parameters are a=10.342(2) Å, c=5.174(2) Å, V=555.3 Å3, Z=4, and the X-ray density D
x is 13.91 Mgm-3 at room temperature. This compound exhibits superconductivity at T
c= 1.80 K (midpoint), Δ
T
c 220 mK by ac-susceptibility measurement and dc 4-terminal electrical measurement.
Characterization of Si Layers Deposited on (100) Si Substrates by Plasma CVD and Its Application to Si HBTs
Authors: Kondo Masao , Saitoh Tadashi , Tamura Masao , Matsubara Sunao , Miyao Masanobu
Published: February 2005

Studies have been carried out on Si layers deposited on (100) Si substrates by plasma CVD, and on heterojunction devices fabricated with the layers. These Si layers vary from microcrystalline to epitaxial structures depending on substrate surface cleaning and deposition temperature conditions. The characteristics of Si HBTs using these layers as emitters depend greatly on the structures of the layers. Very thin interfacial oxides formed by RCA cleaning are effective in growing homogeneous microcrystalline emitters. Hetero-junction effects exemplified by high current gains at room and low temperatures demonstrated the usefulness of the microcrystalline emitters for HBTs and future BiCMOS technology.
Critical Elasticity of Gelatin Gel
Authors: Ikeda Takahiro , Tokita Masayuki , Tsutsumi Akihiro , Hikichi Kunio
Published: February 2005

The elastic behavior of aqueous gelatin gel was studied in the immediate vicinity of the sol-gel transition point. It was found that the elasticity of gelatin gel consists of two parts, `background elasticity'and `critical elasticity'. The background elasticity does not vanish in the sol phase. The site-bond percolation model was found to be applicable to the critical elasticity. Values of the elasticity exponent obtained in this study were 1.71 for the concentration dependence and 1.86 for the temperature dependence. The results are in good agreement with the theoretical prediction for the three-dimensional percolation system.
Studies on the Molecular Orientation of Flavin Langmuir-Blodgett Films by FT-IR Spectroscopy
Authors: Suzuki Sonoko , Isoda Satoru , Maeda Mitsuo
Published: February 2005

The molecular orientation of flavin Langmuir-Blodgett films was studied by FT-IR transmission, reflection absorption and polarized transmission spectroscopy. It was concluded from these measurements that the flavin (isoalloxazine) ring takes a biaxial orientation; the long axis of the isoalloxazine ring almost takes an in-plane orientation to the substrate plane and is almost parallel to the dipping direction of the substrate at the time of preparation of the film. It was also concluded that the short molecular axis is oriented obliquely to the film plane.
A Model for the Silicon Wafer Bonding Process
Authors: Stengl R. , Tan T. , Gösele U.
Published: February 2005

The bonding speed (or contact wave velocity) of silicon and fused quartz wafers has been measured as a function of temperature. The results show that the bonding process stops to operate at temperatures above 90°C and 320°C for fused quartz and bare silicon wafers, respectively.
By comparing our results to infrared spectra obtained from silica gel we develop a tentative model of the bonding process. This model is based on the assumption that the initial wafer bonding process occurs via hydrogen bonds of adsorbed water. This model explains why the bonding strength increases in two distinct steps during high temperature annealing. By introducing a phenomenological time constant τ we can also account for the fact that in an intermediate temperature range the bonding strength does not depend on annealing time as it has been reported in the literature.
Analyses of Noise in a Highly Sensitive Image Device
Authors: Taketoshi Kazuhisa , Tanioka Kenkichi , Andoh Fumihiko , Yamazaki Junichi , Takasaki Yukio
Published: February 2005

A dipole charge-discharge (i.e., DCD) model was proposed to explain the excess noise factor (i.e., θ) of an amorphous selenium APD target below unity beyond the theoretical limit of shot noise. If the dipole distribution between stored holes and electrons is proper, the electric field in the target is formed between storage periods without interfering with the reading-writing mechanism for the signal, and can control the number of stored carriers so that θ becomes smaller than unity. The theoretical relationship between the signal (i.e., I
s) and was obtained and could explain the experimental value well. The theoretical photoelectric conversion characteristics were obtained, and agreed with the experimental values obtained at a high illumination intensity. The magnitude of the negative lag was calculated and was in good agreement with the experimental value.
Studies on Photo-Effects in Semiconductor Surfaces
Authors: De S. S. , Ghosh A. K. , Pattanayak T. K. , Pal P. K. , Halder J. C. , Chatterji A. , Lahiri A.
Published: February 2005

Photo-voltage at the semiconductor surface has been investigated by using a new solution of Poisson-Boltzmann equation. Brattain and Bardeen modex for surface traps has been taken in the formulation. Dependence of normalised surface photo-voltage on surface potential under different carrier densities has been estimated and the results are presented graphically.
Formation of Quasicrystalline Aluminium-Vanadium and Aluminium-Chromium Fine Particles by Gas-Evaporation Technique
Authors: Okazaki Tsugio , Maki Takasi , Saito Yahachi , Mihama Kazuhiro
Published: February 2005

Fine particles in icosahedral phase have been prepared by the gasevaporation method, and studied by electron microscopy. The particles are spherical ranging from 20 to 300 nm in diameter and show a characteristic contrast with an irregular striation. Edge lengths of the fundamental hexahedron in the Penrose tiling are 0.474±0.002 nm in the Al–V system and 0.473 ± 0.003 nm in the Al–Cr system. Though most of the quasicrystalline particles are in a single phase, composite particles of the icosahedral phase and the crystalline phase(β–Al6V) are also observed in the Al–V system. From the orientation relationship between the two phases, atomic sites of vanadium in the icosahedral phase are discussed.
Growth Mechanism of GaAs during Migration-Enhanced Epitaxy at Low Growth Temperatures
Authors: Horikoshi Yoshiji , Kawashima Minoru
Published: February 2005

The growth process of GaAs during migration-enhanced epitaxy at low temperatures is investigated using reflection high-energy electron diffraction. Observation of specular beam intensity during growth reveals that a flat growing surface is maintained at 300°C even when the number of Ga atoms deposited per cycle is not equal to the surface site number. The composition at the growing surface can deviate considerably from stoichiometry at low temperatures because of excess As adsorpt ion. This problem is avoided by optimizing the number of As4 molecules deposited per cycle. The optimum number of As4 molecules was discussed with respect to the number of Ga atoms on the growing surface.
Compact High-Pressure Light Scattering Cell with Low Stray Light
Authors: Hikita Tomoyuki , Ishida Kazunari , Ikeda Takuro
Published: February 2005

We have designed and constructed a compact high pressure light scattering cell which can hold a cube sample as large as 10×10×10 mm3. The cell dimension is about 10×8×10 cm3, and the body material is beryllium-copper alloy. The large sample ensures a low stray light level and the new design for the light collection window permits a large light collection angle (18°). The simple sealing method enables even inexperienced personnel to use this optical cell. We have tested the cell up to a pressure of 0.8 GPa by recording the low-lying Raman spectra of a ferroelectric crystal KH2PO4.
Multiple Oscillation of Near-IR and Red Lasers by Longitudinal-Discharge Excitation of Calcium Vapor
Authors: Kuzumaki Norimitsu , Inoue Masayuki , Taniguchi Hiroshi , Saito Hiroshi
Published: February 2005

Calcium vapor was longitudinal-discharge excited to observe a multiline oscillation of near-IR lines (λ=854.2, 866. nm) and a red-line (λ=644.9 nm). The wavelength of the red-line corresponded well to that of the transition of the neutral calcium atom (4p'(1D2
0)→3d(3D1)). Multiple oscillation was generally observed in a temperature range of 600°C to 800°C. The output power of the red laser occupied about 3.0% of the total output.
Ta/SiN-Structure X-Ray Masks for Sub-Half-Micron LSIs
Authors: Ohki Shigehisa , Kakuchi Masami , Matsuda Tadahito , Ozawa Akira , Ohkubo Takashi , Oda Masatoshi , Yoshihara Hideo
Published: February 2005

In the subtractive X-ray mask fabrication process, suppressing distortions introduced in the bulk-Si etching step is of the utmost importance. Influences of absorber and membrane stresses on mask distortions were investigated in order to obtain good position accuracy. The required stress conditions in order to suppress absorber- and membrane-stress-induced distortions are <2×108 dyn/cm2 for Ta, and <5×108 dyn/cm2 for SiN with a thickness of 2 µm. A five-level mask-to-mask overlay accuracy of <0.085 µm (3σ) was obtained by applying these conditions to actual device mask fabrication. Distortions induced in the bulk-Si etching step were drastically suppressed below 0.058 µm (3σ) in these masks. Absorber patterns with linewidths down to 0.14 µm were successfully fabricated. Pattern position shifts occurring in the frame-mounting step are dominant in our X-ray mask fabrication process.
Laser-Induced Etching of Mn-Zn Ferrite an Its Application
Authors: Lu Yong Feng , Takai Mikio , Nagatomo Syohei , Minamisono Tadanori , Namba Susumu
Published: February 2005

Single-crystalline ferrite was masklessly etched by focused Ar+ laser irradiation in CCl4 gas and in H3PO4 solution. Etching rates up to 68 µm/s in CCl4 and 340 µm/s in H3PO4 have been achieved by laser processes. Bending of the etched narrow groove was observed in CCl4 gas due to the enhanced reflection caused by the polarization of the laser beam when focused by a microscope objective lens. A vertical slab structure with a high aspect ratio of up to 40 has been obtained by the light-guiding effect of the laser beam in wet-chemical etching. RBS analysis of the processed surface revealed that laser-induced damage was much lower than that induced by mechanical polishing.
Fabrication of Deep Sub-µm Narrow-Channe1 Si-MOSFET's with Twofold-Gate Structures
Authors: Yoshimura Toshiyuki , Igura Yasuo , Ichiguchi Tsuneo , Matsuoka Hideyuki , Takeda Eiji , Okazaki Shinji
Published: February 2005

Deep sub-µm narrow-channel Si metal-oxide-semiconductor field-effect transistors (Si-MOSFFT's) are fabricated using conventional LSI processes together with electron beam lithography. The device comprises a twofold-gate structure in which a narrow gate is covered with a wide gate. With this structure, effective channel widths can be narrower than those achieved by lithography. Peak-and-valley structures are found in transconductance at low temperatures. They are thought to originate in quasi-one-dimensional subbands.
Transport Properties of Ions in Ferroelectric Liquid Crystal Cells
Authors: Chieu T. C. , Yang K. H.
Published: February 2005

The transient ionic current in a ferroelectric liquid crystal (FLC) cell was measured as a function of applied voltage at different temperatures. The measured current shows a delay peak which decays rapidly to a steady-state value. The steady-state current exhibits a thermal activated behavior with an activation energy of 0.94 eV, and depends exponentially on the square root of the field strength similar to the Schottky effect. To describe the transport behaviors of the ions, a model with ionization-recombination equations which include a field-dependent ionization coefficient, and a continuity equation for the accumulated surface charges has been introduced. According to the model, the current decay time and the peak position of the delay peak current can be used to determine the ion mobility. Two ionized species have been identified in the FLC medium: a weakly ionized species with a relatively constant mobility of 2.0×10-7 cm2/V·s, and a highly ionized species with a room temperature mobility of 4.1×10-7 cm2/V·s and a thermal activation energy of about 0.71 eV. Detailed calculation of the ionic current and comparison with experimental results are given.
Temporal Behaviors of Flash X-Ray Source Driven by a Low-Energy Capacitor Discharge
Authors: Ko Kwang Cheol , Hoshina Yoshikazu , Ishii Shozo
Published: February 2005

Temporal behaviors of a compact X-ray source driven by a low-energy capacitor discharge have been studied. X-rays are emitted only when the voltage appears between the anode and cathode at the beginning of the discharge, when the discharge current is small. The temporal X-ray emission profile has a significant correlation with the electrode voltage. Therefore, high discharge currents and high-energy capacitors are unnecessary. Spectral and spatial properties of the X-ray source are investigated by aluminum filters and thermoluminescent dosimetry. When the generator output voltage is 95 kV, the photon energy ranging from 15 to 30 keV is nearly 63% of the emitted X-ray and the maximum photon energy of 84.7 keV is obtained. Applying the experimental results, we propose a variable short-wavelength pulsed-light source.
Contribution of Higher Harmonic Resonance on the Production of ECR Mirror Plasma by 60 GHz Gyrotron
Authors: Arata Yoshiaki , Miyake Shoji , Kishimoto Hiroaki
Published: February 2005

In ECR plasma production in a simple mirror field using a high-power 60 GHz gyrotron, the contribution of higher harmonic resonance is studied experimentally by an energy-dispersive measurement of the radial distribution of soft X-ray emissions with a gas flow-type proportional counter. Existence of the fundamental resonance zone within the vacuum chamber was confirmed to be necessary for the efficient ignition of the plasma. A remarkable difference in the warm and/or hot electron distribution was found in the radial and axial launches of the wave at a low power input under the same magnetic field configuration.
Silicon Oxide Film Formation by Focused Ion Beam (FIB)-Assisted Deposition
Authors: Komano Haruki , Ogawa Youji , Takigawa Tadahiro
Published: February 2005

A silicon oxide film has been formed by means of 60 keV Si2+ focused ion beam (FIB)-assisted deposition. A mixture of tetramethoxysilane (Si(OCH3)4) and oxygen gases was blown onto a sample surface through a 0.2-mm-inner-diameter nozzle. A gold, silicon, and beryllium alloy source was used to produce a Si2+ ion beam in the FIB system. The beam diameter and current were 0.3 µm and 0.1 nA, respectively. The deposited film with 0.1-µm thickness and 0.7-µm width consisted mainly of silicon and oxygen, and contained scarcely any carbon. The relative ratios of silicon to oxygen atomic concentration were 1:2 near the film surface and 1:1 inside the film. The resistivity of the deposited film was 2.5 MΩ·cm at 5 V, and the breakdown voltage was 40 V. It was found that it would be possible to use the deposited film as an insulator for integrated circuit repair in developing semiconductor devices.
Behavior of Defects Induced by Metallic Impurities on Si(100) Surfaces
Authors: Hourai Masataka , Murakami Katsumi , Shigematsu Tatsuhiko , Fujino Nobukatsu , Shiraiwa Toshio
Published: February 2005

The formation of defects induced by Ni, Cu and Fe and their retardation by intrinsic gettering (IG) were studied under several heat treatments. The behavior of Fe in Si was different from that of Ni and Cu. After annealing at 1150°C and subsequent cooling, shallow pits (SP) due to Ni and Cu precipitates were observed only at the surface. Fe precipitation was obtained by holding at temperatures below 850°C, where Fe was supersaturated in the matrix. We believe that metal precipitation is dominated by the diffusion rate. During additional oxidation, oxidation-induced stacking faults (OSF) were transformed from each precipitate. It seems that metal precipitates act as nuclei of OSF. Effects of IG for the three elements were compared. The retardation of defects induced by Fe was less than that of Ni and Cu. This difference is closely related to the growth rate of Fe precipitates.
Defect Formation in GaAs by Subthreshold Energy (0.2–3 keV) Electron Irradiation
Authors: Nel M. , Auret F. D.
Published: February 2005

Defects formed in epitaxially grown GaAs after low energy (0.2–3 keV) electron irradiation were investigated by deep level transient spectroscopy (DLTS) and compared with high energy (1–5 MeV) electron irradiation induced defects. The results indicated that electrically active defects could be created at electron irradiation energies of as low as 0.2 keV. These defects are formed close to the GaAs surface, and a higher than usual DLTS forward bias filling pulse was required to detect them. Further, the properties of defects formed at irradiation energies of 0.2–3 keV correspond well with those of MeV energy range electron irradiation induced defects, but their introduction rates were much lower.
Integrated Optic Accelerometer Employing a Cantilever on a Silicon Substrate
Authors: Ohkawa Masashi , Izutsu Masayuki , Sueta Tadasi
Published: February 2005

A novel integrated optic accelerometer employing a cantilever on a silicon substrate is proposed. An analysis is carried out to demonstrate the feasibility of the proposed sensor and obtain the basic design concept. The sensitivity and the detectable frequency range of the acceleration can be set by proper selection of the cantilever dimensions and the added weight.
Electroluminescence of SrS Thin Films Activated with Nd3+, Sm3+, Dy3+, Ho3+, and Er3+ Ions
Authors: Okamoto Shinji , Nakazawa Eiichiro , Tsuchiya Yuzuru
Published: February 2005

Thin electroluminescent SrS films activated with Nd3+, Sm3+, Dy3+, Ho3+, and Er3+ ions have been investigated. Their emission colors are found to be orange-white, orange, yellow, greenish white and green respectively, originating from transitions within the 4fn configuration of the rare-earth ions. The luminance levels of these devices are all over 200 cd/m2, except for that of SrS:Ho3+ (110 cd/m2), on the application of a driving voltage in the range 70–100 V with a frequency in the range 3 k–5 kHz. The main spectral regions of these spectra are found to shift to shorter wavelengths in comparison with those of the same ions in ZnS-based TFEL devices.
Optical Field-Induced Electric Bistability and the First-Order Electric Freedericksz Transition in a Homeotropic Nematic Film
Authors: Wu J. J , Chen Shu-Hsia
Published: February 2005

This paper reports on the observation of electric bistability and a first-order electric Freedericksz transition induced by an optical field in a homeotropic nematic liquid crystal film. Molecular reorientation as a function of electric field is characterized by an unambiguous hysteresis loop which exhibits electric bistability. The experimental results match the numerical/theoretical results fairly well. The tricritical point will also be discussed.
Temperature Dependence of Plastic Deformation in White Tin Single Crystals
Authors: Nagasaka Muneo
Published: February 2005

Tensile experiments have been carried out over a wide range of temperatures on single crystals of high-purity white tin with low dislocation density. From the observations of slip lines it is found that different slip systems are activated for different temperature regions and for different orientations of specimens. By deformation with the (100)[010] slip system the cell structure is formed in the specimen. The critical-resolved shear stress of this system shows a similar temperature dependence to that of cubic metals. In the case of the (11̄0)½[111] slip system, only isolated dislocations are formed during deformation and the yield point phenomenon occurs. The critical-resolved shear stress of this system shows a strong temperature dependence not found in cubic metals. It increases nearly exponentially with decreasing temperature and attains a factor of 200.
Formation Mechanism of a Monoatomic Order Surface Layer on a Sc-Type Impregnated Cathode
Authors: Yamamoto Shigehiko , Watanabe Isato , Taguchi Sadanori , Sasaki Susumu , Yaguchi Tomio
Published: February 2005

The electron emission of a Sc-type impregnated cathode is known to be enhanced by a monoatomic-order surface layer composed of Ba, Sc, and O. This layer reduces the work function much lower than those of conventional impregnated cathodes.1,2) It also makes the cathode resistant to gas contamination.3) In the present work, a basic impregnated cathode is coated with a thin tungsten film containing a certain amount of Sc2W3O12 (about 5–10 atomic percent) to produce a (W-Sc2W3O12) coated cathode.
The supplying mechanism of free Sc atoms, and hence the monoatomic-order layer formation mechanism,4) is clarified by Auger electron analysis and X-ray diffraction analyses. Free Sc atoms are produced through the following surface chemical reaction between Sc2W3O12 and Ba atoms supplied from the substrate4) as

Sc2W3O12+3Ba=3BaWO4+2Sc.

This monoatomic layer formation improves the electron emission current density measured at 850°Cb (brightness temperature) about threefold compared to that of conventional Os coated impregnated cathodes.
Imaginary Part of the Dielectric Function of Sintered and Microcrystalline Cubic Boron Nitride
Authors: Yokoyama Haruki , Okamoto Masaki , Hamada Tsutomu , Imura Takeshi , Osaka Yukio , Chayahara Akiyoshi , Fujisawa Masami
Published: February 2005

The optical reflectance of cubic boron nitride (c-BN) was measured for sintered and microcrystalline samples at room temperature in the photon energy range 5–25 eV. Kramers-Kronig analysis was performed to determine the real ε
1 and imaginary ε
2 parts of the dielectric function. The spectrum of ε
2 for sintered c-BN shows peaks at 9.05 eV and 11.7 eV and shoulders at 10 eV, 13.2 eV and 16.7 eV. This spectrum was compared with the one theoretically obtained by Tsay et al. and assignment of the structure was made. The ε
2 for microcrystalline c-BN has a broad structure with a peak at 11.7 eV.
Differential Scanning Calorimetry Studies of P-Doped a-Si:H
Authors: Nasu Hiroyuki , Akamatsu Chikashi , Hayashi Ryo , Osaka Yukio
Published: February 2005

Differential scanning calorimetry (DSC) studies of P-doped hydrogenated amorphous silicon (a-Si:H) show characteristic behaviors of the relaxation phenomena related to the defect frozen states. The equilibration temperature T
E
* detected by DSC agrees well with T
E determined by the temperature dependence of dc conductivity. The exothermic reaction detected by DSC is semiquantitatively interpreted by the theoretical model of the equilibrium process of defects.
Surface Binding Energy of Nickel Measured by Laser Fluorescence Spectroscopy
Authors: Muraoka Katsunori , Suenaga Kiyoyuki , Morita Kenji , Yamagata Yukihiko , Kim Hee Je , Honda Chikahisa , Maeda Mitsuo , Akazaki Masanori
Published: February 2005

The surface binding energy of nickel was estimated from the measured velocity-distribution function of sputtered nickel atoms by rapid-frequency-scan laser spectroscopy, yielding 1.2±0.5 eV, which was about one third of the sublimation energy of nickel. The results were interpreted as the formation at the surface of a carbide phase which weakened the binding of atoms, compared with that in pure nickel.
CW Laser Heating Effects and Mode Splitting of the Raman Spectra of the (Dy and Y)Ba2Cu3O7-δ Superconductors
Authors: Huang Chien-Rong , Chang Yung-Sheng , Lee Ming-Chih
Published: February 2005

The Raman spectra of the (Dy and Y)Ba2Cu3O7-δ high-T
c superconductors under various laser excitations have been measured. Using low probe powers, there are three prominent peaks at 501, 597, and 608 cm-1 in DyBaCuO, and 502, 599, and 609 cm-1 in YBaCuO besides the weak Raman features at 341, 435, and 556 cm-1. A reproducible splitting around 600 cm-1 in both samples is observed for the first time, which is not due to the presence of the Y2BaCuO5. Under moderate excitations, the splitting modes become unresolved while the 501 (or 502) cm-1 peak looks unchanged. However, only after strong laser heating, the newly appearing peak at 635 cm-1 and the triangular feature around 588 cm-1 together indicate the formation of the well-known impurity BaCuO2. But the Y2O3 compound is formed instead for the laser-treated Y2BaCuO5 sample. Our results show the significance of the laser heating effects on the interpretation of the Raman signals. The observed splitting is tentatively assigned to the nondegenerate B2g and B3g modes of the in-plane copper and oxygen vibrations which provides an alternative of distinguishing the orthorhombic from the tetragonal phase.
Magnetic and Electrical Properties of Bi2O3 Modified BaFe12O19 Hexagonal Ferrite
Authors: Ram S. , Krishnan H. , Rai K. N. , Narayan K. A.
Published: February 2005

The Ba-hexagonal ferrites (BaFe12O19) with Bi2O3 as a sintering aid have been studied. The beneficial effects on magnetic and electrical properties are obtained for a ∼2.5 mol% Bi2O3 content. The Bi3+ ions in the present system seem to substitute for Fe3+ at octahedral sites leading to formation of BaFe12-x
Bi
x
O19 (x<0.32) type ferrite. It leads ∼12.4% decrease of the saturation magnetization and an increase of T
c from 457 to 480°C in comparison to pure Ba-ferrite. Coercivity (H
c) is found to decrease on Bi2O3 addition and sintering the samples at higher temperatures (1100–1300°C) for prolonged periods. The bulk density, compressive strength and electrical (AC) resistivity are measured for all the useful samples. The results considered together successfully account for the effects of Bi2O3 on the growth of Ba-ferrite particles.
Multiexponential Analysis of Deep Level Transient Spectroscopy (C2-MEDLTS)
Authors: Morimoto Jun , Tashiro Syuuji , Tahira Kenichiro , Miyakawa Toru
Published: February 2005

A novel method of analyzing the deep impurity levels in semiconductors is proposed. This method analyzes the square of the transient junction capacitance waveforms as multiexponentials by using the nonlinear least squares method and is referred to as C2-MEDLTS. The effect on the emission rate τ of the deep levels in the nonionized region (λ-effect) is included. It allows correct evaluation of the activation energies and capture cross sections even for the high concentrations of closely spaced deep levels (N
T/N
D ≃ 1).
Local Structures and Annealing Behavior of Amorphous TexC1-x Alloys Prepared by rf Sputtering
Authors: Tsunetomo Keiji , Sugishima Tatsumi , Imura Takeshi , Osaka Yukio , Sakai Hiroshi
Published: February 2005

The local structures and annealing behavior of amorphous Te
x
C1-x
films (x=0.1, 0.17 and 0.51) prepared by rf sputtering are investigated in order to examine the possibility of optical recording media. Measurements of optical absorption, X-ray diffraction, Raman scattering, and transmission electron microscopy reveal that amorphous Te
x
C1-x
films consist of amorphous Te clusters about 30 A in diameter embedded in amorphous carbon. Mössbauer spectroscopy of 125Te and 129I is also applied to these alloy films in order to elucidate the local environment of the tellurium atom. The Mössbauer spectra suggest that the interaction between Te chains in the amorphous clusters is weak compared to that in the crystalline Te and decreases with decreasing Te content.
An MINPIM Structure Mixing Device
Authors: Chang David C. Y. , Lee Chung Len , Lei Tan Fu
Published: February 2005

A device of the MINPIM structure is proposed and demonstrated to work as a mixer. It employs two MIS junctions connected face-to face with a reversely biased P-N junction to form two MISS transistors in a series to perform mixing. The device was fabricated in a V grooved structure, and its mixed I–V characteristics are presented.
Crystal Structures of Superconducting LnBaAeCu3Oy (Ln=La, Nd; Ae=Ca, Sr)
Authors: Fujishita Hideshi , Shamoto Shin-ichi , Onoda Masashige , Sato Masatoshi
Published: February 2005

Crystal structures of LaBaCaCu3O
y
, NdBaCaCu3O
y
and LaBaSrCu3O
y
were analyzed by the X-ray Rietveld method. Their chemical formulae were different from the nominal compositions owing to the formation of impurities. They were obtained as La1.23Ba1.23Ca0.54Cu3O
y
, Nd1.26Ba1.26Ca0.48Cu3O
y
and La1.14Ba1.14Sr0.72Cu3O
y
, respectively. Ca2+ or Sr2+ ions were found to enter not only the Ba2+ sites but the La3+ or Nd3+ sites as well. The occupancy of Ca2+ or Sr2+ at La3+ or Nd3+ sites was found to correlate with their ionic radii.
Electrical Characteristics of Metal Contacts to Boron-Doped Diamond Epitaxial Film
Authors: Shiomi Hiromu , Nakahata Hideaki , Imai Takahiro , Nishibayashi Yoshiki , Fujimori Naoji
Published: February 2005

Current-voltage characteristics have been obtained for various metal contacts formed on boron-doped diamond epitaxial film prepared on synthesized Ib diamond by the microwave plasma-assisted chemical vapor deposition method. Ti contacts and W contacts have exhibited good ohmic and Schottky properties, respectively. For the first time, we have fabricated Schottky diodes on boron-doped diamond epitaxial films using these contacts and investigated their properties.
Photo-Assisted Metal Organic Chemical Vapor Deposition Preparation of Polycrystalline ZnS:Mn Films for Thin Film Electroluminescent Devices
Authors: Hirabayashi Katsuhiko , Kozawaguchi Haruki
Published: February 2005

Polycrystalline ZnS:Mn films with good crystallinity are grown by photo-assisted MOCVD using dimethylzinc and diethylsulphide. The growth temperature is decreased from 550 to 400°C by photo-irradiation (high-pressure mercury lamp) and no dead layer results. Patterned ZnS films can also be grown by this method. Thin film electroluminescent devices fabricated using these films have lower threshold voltages.
Analysis of Macroscopic Stability as an Eigenvalue Problem of Beam Propagation in LIB Fusion
Authors: Kaneda Takeshi , Niu Keishiro
Published: February 2005

Stability of LIB propagation in a background plasma is investigated numerically in relation to its rotating velocity. First, a steady solution is obtained. The linearized equations which govern a Fourier component of disturbances induced on the steady solution constitute an eigenvalue problem. The dispersion relation as the eigenvalue is solved numerically through the eigenequations by dividing the beam radius into many subdivisions, and by applying the difference equations (transformed from the linearized differential equations) to each subdivision. The maximum growth rate of disturbances appears in the fundamental mode in the radial direction and in the lowest Fouriercomponent with respect to the wave numbers in the azimuthal direction. It is indicated here that the moderate rotation of the beam stabilizes the beam propagation.
Tungsten-Carbon X-ray Multilayered Mirror Prepared by Photo-Chemical Vapor Deposition
Authors: Suzuki Yoshihiko
Published: February 2005

A tungsten-carbon(W/C) X-ray multilayered mirror was prepared by photoinduced chemical vapor deposition (photo-CVD) using a low-pressure mercury lamp and an argon-fluoride (ArF) excimer laser. The 40% reflectivity of this mirror was measured using a small-angle X-ray diffractometer with Cu-Kα radiation. This reflectivity is lower than the theoretical reflectivity of 80%. From observations of the transmission electron micrograph from this multilayered mirror, it seems that the reduction of the reflectivity was caused by the indistinct interfaces of the diffused films, and by the roughness of the films introduced by partial crystallization of the tungsten films.
Optical Mapping of the Total EL2-Concentration in Semi-Insulating GaAs-Wafers
Authors: Zach F. X. , Winnacker A.
Published: February 2005

In semi-insulating GaAs wafers the distribution of the total EL2, independent of its charge state, was determined by purely optical absorption measurements. In all (Czochralski-grown) wafers studied the radial distribution of the total EL2 is W-shaped and shows fourfold symmetry. So the fluctuations of the neutral EL2-concentration seen in the usual near infrared transmission mapping reflect essentially the inhomogeneity of the total EL2 distribution. The mean EL2+ concentration in all wafers was close to typical C- and Zn-concentrations in s.i. GaAs (≈ 2·1015 cm-3).
Electroluminescence and Photoluminescence in Eu-Doped SrS Thin-Films
Authors: Xian Hong , Zhong Guozhu , Tanaka Shosaku , Kobayashi Hiroshi
Published: February 2005

The electroluminescence (EL) and photoluminescence (PL) characteristics of SrS:Eu, F thin-films have been studied. It is found that valence of the Eu luminescent centers is affected by the presence of F- ions. At lower Eu concentration less than 0.3 mol%, Eu2+ centers exist, but at higher concentration over 0.6 mol%, both Eu2+ and Eu3+ centers coexist in the films. The Eu2+ centers are efficient for both EL and PL. The excitation process of Eu2+ centers is attributable to the energy transfer from the SrS lattice to Eu2+ centers. On the contrary, Eu3+ centers are efficient for EL only through the direct impact excitation by hot electrons.
Photoconductivily of Poly(3-alkylthiophene) in Solid and Liquid States
Authors: Yoshino Katsumi , Sawada Keiji , Onoda Mitsuyoshi
Published: February 2005

Photoconductivity has been observed in poly(3-alkylthiophene), not only in the solid state but also in the liquid state. Irradiation of the anode induces photoconductive response for a photon energy smaller than the band gap. On the other hand, upon irradiation of the cathode, photoconductivity was observed for light of photon energies both higher and lower than the band gap. Photoconduction is also strongly dependent on temperature. Especially remarkable is photoconductivity in the liquid phase upon irradiation of the cathode with light of photon energy larger than the band gap. These results support the hypothesis that the electronic band scheme is also applicable to the liquid state.
Interaction of Laser Blow-Off Blob with a Low-Pressure Gas Discharge
Authors: Okuda Takayoshi , Adachi Hiroyuki
Published: February 2005

The laser blow-off blob produced in front of the thin film of a metal is composed of the partially ionized vapor and molten droplets of the metal. When the blob is injected across a low-pressure argon discharge, the discharge current first increases and then slowly decreases. Subsequently, the discharge current either recovers its steady value or continues to decrease until the discharge is disrupted, depending on the size of the discharge current. Examining the experimental results obtained by various diagnostics, we discuss the possible mechanisms of the interaction of the laser blow-off blob with the low-pressure argon discharge.
Scanning Isothermal Current Transient Spectroscopy (SICTS) and Its Application to the Microscopic Distribution Measurement of Gap States in Hydrogenated Amorphous Silicon Films
Authors: Tokumaru Yozo , Okushi Hideyo , Naka Hiroyoshi
Published: February 2005

Scanning isothermal current transient spectroscopy (SICTS) is proposed for the microscopic deep-level distribution measurement in semiconductors and applied to the spatial distribution measurement of gap states in hydrogenated amorphous silicon films.
A Si Single-Crystal Shield-Pipe for Precise Measurement of Synchrotron Radiation Induced Gas Desorption
Authors: Murashita Toru , Kakeko Takashi , Yoshihara Hideo , Kobayashi Masanori
Published: February 2005

The shield effect of a pipe is estimated as a function of its dimensions. Si Single crystal is chosen as the pipe material based on experimental results showing that its outgassing rate is lower than that of SUS 304 stainless steel. The Si single-crystal shield-pipe effectiveiy prevents environmental PSD and is a powerful tool for precise PSD measurement of low-PSD materials.
The Mechanism of Self-Limiting Growth of Atomic Layer Epitaxy of GaAs by Metalorganic Molecular Beam Epitaxy Using Trimethylgallium and Arsine
Authors: Watanabe Akiyoshi , Isu Toshiro , Hata Masayuki , Kamijoh Takeshi , Katayama Yoshifumi
Published: February 2005

The self-limiting growth of atomic layer epitaxy by metalorganic molecular beam epitaxy using trimethylgallium (TMGa) and arsine (AsH3) was studied as a function of substrate surface condition. It was observed that GaAs growth from TMGa and AsH3 is limited to 1 monolayer (ML) on an As-stabilized surface and that TMGa can adsorb on a Gacovered surface. In-situ observation of RHEED intensity showed that the TMGa in excess of 1 ML on the GaAs substrate desorbed after TMGa supply was stopped. It was found that self-limiting monolayer growth resulted from desorption of the excess TMGa.
Scanning Internal-Photoemission Microscopy: New Mapping Technique to Characterize Electrical Inhomogeneity of Metal-Semiconductor Interface
Authors: Okumura Tsugunori , Shiojima Kenji
Published: February 2005

A new mapping technique, termed scanning internal-photoemission microscopy, has been presented to characterize the electrical inhomogeneity of metal-semiconductor interfaces. To obtain images of a Schottky barrier height, we have used two laser beams in a 1 µm band for which Si and GaAs substrates are transparent, and thus the proposed technique has been capable of probing the metal-semiconductor interfaces directly. The capability of this microscopy has been demonstrated by visualizing the parallel contact with two different metals, the existence of mechanical damage, and an ultrathin layer buried beneath a thick metal.