bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Analysis of a Fibre-Optic Ring Resonator Excited by a Sinewave-Modulated Laser Diode
Authors: Pandian G. Soundra , Seraji Faramarz E.
Published: February 2005

This article describes a theoretical dynamic analysis of a fibre-optic ring resonator (FORR) when excited by a sinusoidally-modulated laser diode (LD). The results are given for different conditions of the resonator, namely, modulating frequency, amplitude modulation index, power coupling coefficient of coupler, loop delay time τ and the phase angle between FM and AM response of the LD. When the modulation frequency f
m exceeds a limiting value, such that f
mτ is greater than about 0.0002, the output response deviates from steady state and exhibits an oscillatory behaviour with overshoots. Also, when the value of f
mτ becomes greater than one, the response does not show any resonance in the ring and the output approximates to the intensity modulation of the LD. An unknown FM characteristic of a given LD can be determined from the ring resonator response.
Cu3N Thin Film for a New Light Recording Media
Authors: Asano Masaaki , Umeda Kazuo , Tasaki Akira
Published: February 2005

Copper nitride thin films were prepared by using the ion-assisted deposition in which accelerated nitrogen ions were irradiated during the deposition of copper metal. The degree of nitrification of the film was controlled by changing the ion current density. The reflection coefficient of the prepared copper nitride films decreased with the increase of the ion current density. The reflection coefficient was about 30% at 780 nm wavelength, and it recovered to 70% after the film was heated at 300°C. The preliminary experiment of write-once optical recording of this film was carried out, and the viability of its practical use in new media was confirmed.
Temperature Dependence of Electron Mobility in InGaAs/InAlAs Heterostructures
Authors: Matsuoka Toshimasa , Kobayashi Eisuke , Taniguchi Kenji , Hamaguchi Chihiro , Sasa Shigehiko
Published: February 2005

Temperature dependence of the electron mobility in modulation-doped InGaAs/InAlAs single heterostructures has been investigated by Hall effect measurements in the temperature range from 15 K to 300 K in order to clarify the scattering mechanisms of the electrons. Two kinds of samples are used with doping densities in the InAlAs barrier layer, N
D=3×1017 cm-3 and 1×1018 cm-3. The measured electron mobility is compared with the calculated values by taking into account the scattering by InAs-like and GaAs-like LO phonons in the InGaAs channel layer, in addition to the acoustic deformation potential, piezoelectric, ionized impurity, alloy disorder and interface roughness scatterings. The calculated electron mobility shows a good agreement with the experimental data when the alloy disorder potential is assumed to be about 0.7 eV.
Electrical Properties of Au/Polyimide/Squarylium-Arachidic Acid Junctions Fabricated by the Langmuir-Blodgett Technique
Authors: Iwamoto Mitsumasa , Shidoh Shun-ichi
Published: February 2005

We fabricated metal-insulator-semiconductor (MIS) junctions having the structure of a Au/polyimide (PI)/squarylium dyearachidic acid (SQ-C20) mixed system by the Langmuir-Blodgett (LB) technique, and then examined the electrical properties of the junctions. It was found that a PI LB film becomes a good electrical insulator even when the number of deposited layers is 5. From the capacitance-voltage (C-V) measurement, it was found that a (SQ-C20) multilayered film is depleted at the interface between the PI layer and the (SQ-C20) layer even when biasing voltage was zero millivolt because positive excess charges are displaced from the gate-Au electrode to the PI layer as deposited. The polyimide layer incorporated in the junctions makes a significant contribution to the electrical conduction, and asymmetric current-voltage (I-V) characteristics were obtained for the junctions.
Characterization of CVD-TiN Films Prepared with Metalorganic Source
Authors: Ishihara Kazuya , Yamazaki Katsumi , Hamada Hidenao , Kamisako Koichi , Tarui Yasuo
Published: February 2005

This paper investigates the structural and electrical properties of TiN films prepared by metalorganic chemical vapor deposition (MOCVD) using a mixture of tetradimethylamino-titanium (Ti(N(CH3)2)4) and NH3 gases. The deposited films changed from a metallic gray to a gold color at a substrate temperature of 300∼580°C. The film resistivity decreases with increasing substrate temperature to 8.4×102 µΩ·cm at 580°C. The preferred orientation was (111) at temperatures over 400°C.
A Chemical-State-Discriminated XPED Study on Structure of Thin CaO Layer Formed by Electron Bombardment Heating on CaF2(111)
Authors: Akita Chiyoshi , Tomioka Takanori , Owari Masanori , Mizuike Atsushi , Nihei Yoshimasa
Published: February 2005

CaF2 in the surface layer with a thickness of a few nanometers was converted to CaO by electron bombardment heating above 300°C, but CaO was not formed by the lamp heating. This conversion is thought to occur by electron bombardment to the sample surface during heating. Furthermore, it was found by chemical-state-discriminated X-ray photoelectron diffraction (XPED) measurements that CaO grew epitaxially on CaF2(111). The crystallographic orientation of the CaO epitaxial layer was directly determined from the analysis of XPED patterns.
Observation of Burn and Pusher Regions of Laser-Driven Large-High-Aspect-Ratio Target by α-Particle Imaging
Authors: Chen Yen-Wei , Miyanaga Noriaki , Yamanaka Masanobu , Azechi Hiroshi , Nishihara Katsunobu , Yamanaka Tatsuhiko , Nakai Sadao , Yamanaka Chiyoe
Published: February 2005

The deuterium-tritium (D-T) thermonuclear reaction region of a laser-driven large-high-aspect-ratio target, which contains D-T mixture gas, has been diagnosed with an α-particle imaging technique using a pinhole camera. The residual pusher region at the maximum compression has also been observed as an image of scattered α-particles. Comparison between the α-particle image and a two-dimensional hydrodynamic simulation shows that laser energy balance significantly influences the implosion uniformity.
Spectroscopic Measurements of the Production and the Transport of CH Radicals in a Methane Plasma Used for the CVD of a-C:H
Authors: Tachibana Kunihide , Mukai Takuya , Yuuki Akimasa , Matsui Yasuji , Harima Hiroshi
Published: February 2005

Spatial and temporal variations of CH radicals in an rf discharge in methane for the deposition of amorphous carbon film were measured by optical emission spectroscopy and laser-induced fluorescence (LIF) spectroscopy. The temporal variation of CH emission from the excited A2Δ state suggested that the electron energy was deeply modulated by the rf field. The spatial distribution of CH in the ground X2Π state showed a broader profile than the time-averaged emission profile of CH(A2Δ), indicating the broader spatial production pattern for the CH(X2Π) and its diffusional transport. The absolute density of CH(X2Π) was also obtained, from which the flux of CH onto the substrate was estimated. The density and the spatial profile of CH were strongly affected by diluent Ar gas. These results were compared with a simulation and discussed in relation to the film deposition.
Model Study of Spontaneous Discharge Fluctuations of a Membrane Potential
Authors: Sano Sano , Motoaki Motoaki , Nakauchi Nakauchi , Hidehiro Hidehiro , Akabane Akabane , Hideo Hideo , Musha Musha , Toshimitsu Toshimitsu
Published: February 2005

A discharge model is presented to simulate self-induced oscillations of a tonically autoactive neuron (TAN) of an African giant snail and a dioleyl phosphate (DOPH) Millipore membrane system. In this model, the pulse interval is determined by the accumulated ionic charges in a cell and the threshold level of discharge. The relationship of the fluctuations of these two parameters to the discharge interval fluctuations is simulated.
Morphology of Microdefects in As-Grown Thinned Silicon Crystals Observed by Synchrotron X-Radiation Plane-Wave Topography
Authors: Chikaura Yoshinori , Imai Masato
Published: February 2005

In order to reveal more minute microdefects in as-grown CZ silicon crystals, thinned crystals as thin as the order of the extinction distance have been successfully observed by ultra plane-wave topography using synchrotron X-radiation. Various kinds of microdefects reveal themselves only in the thinned region. Using thinned crystals for plane-wave topography is essential for the present experiment. Observed morphologies of microdefects are classified into five categories. One of the observed microdefects has an image extinction rule suggesting a specified strain field around it. The morphology of microdefects has been described in detail.
Phase Coherence Length in Planar Doped Thin GaAs Wires Fabricated by Ion Beam Etching
Authors: Taniguchi Hiroaki , Nagoya Tasuku , Takagaki Yukihiko , Yuba Yoshihiko , Takaoka Sadao , Gamo Kenji , Murase Kazuo , Namba Susumu
Published: February 2005

Electrical transport properties have been studied in a film and wires fabricated from a monolayer doped or a homogeneously doped thin GaAs by mesa etching techniques. The dependence of the electron wave coherency upon the wire widths and fabrication processes is investigated from their low-temperature behavior of the phase coherence length L
φ derived from the nagative magnetoresistance and the amplitude of the conductance fluctuations. Low-temperature saturations of L
φ occur only in narrow wires. This suggests that L
φ is affected by the ion beam induced damage within the mesa side walls. A difference in L
φ between reactive ion-beam-etched and ion-milled wires is explained by the decrease of the diffusion constant. The corresponding difference in the conductance fluctuation amplitudes is larger than that expected from the difference in L
φ.
Analysis of Deposition Selectivity in Selective Epitaxy of GaAs by Metalorganic Chemical Vapor Deposition
Authors: Yamaguchi Ko-ichi , Okamoto Kotaro
Published: February 2005

In GaAs-selective epitaxy by atmospheric-pressure MOCVD using W and SiO2 masks, the observed difference of the deposition conditions can be explained by two different mechanisms of heterogeneous nucleations (HN) on the mask surfaces. One is HN on ideally flat mask areas (case I), and the other is HN at irregular nuclei on the mask surfaces (case II). Surface concentration of reactant species on masks is analyzed by applying the surface-diffusion model to reactant species on the masks, and, for case I, the calculated results of polycrystal deposition on W and on SiO2 masks are compared with experimental ones. It becomes apparent that the occurrence of the thick polycrystal deposition frequently observed on W masks is due to high surface concentration. Products of the surface-diffusion coefficient and the stagnantlayer thickness are estimated as 6.25 cm3/s for W masks and 169.5 cm3/s for SiO2 masks at 610°C.
Growth and Characterization of Bi2(Sr1-xCax)3Cu2Oy Single Crystals Extracted from KBr Flux
Authors: Shishido Toetsu , Toyota Naoki , Shindo Daisuke , Fukuda Tsuguo
Published: February 2005

Single crystals of Bi-based compounds were obtained by the high-temperature solution growth method using KBr as the flux. The compositions of two typical compounds were determined as Bi2.2Sr1.8Ca1.1Cu2O
y
and Bi2.1Sr1.1Ca1.6Cu2O
y
, which are close to the chemical formula Bi2(Sr1-x
Ca
x
)3Cu2O
y
. The magnetization experiment shows that the onset temperatures of T
c of the two compounds are 98 K and 83 K, respectively.
Role of Silicon Self-Interstitials Injected by Thermal Oxidation in Oxygen Precipitation in Czochralski Silicon
Authors: Yamanaka Hideki , Aoki Yoshihira , Samizo Takahide
Published: February 2005

The retardation of oxygen precipitation due to silicon self-interstitials has been investigated by varying the growth rate of a silicon oxide film and the carbon concentration of the silicon wafers. This retardation was found to relate to the decrease in the number density of oxygen precipitates near the oxidized wafer surface. This can be understood by considering that the critical radius of oxygen precipitation nuclei varies depending on the depth from the wafer surface in the early stage of the heat treatment. Moreover, the reduction of the precipitated oxygen concentration was found to significantly increase with slightly increasing carbon content. This carbon effect may be explained by assuming that a larger number of smaller precipitation nuclei would exist in the high-carbon wafers than in the low-carbon ones after the low temperature annealing.
ECR Plasma CVD Using a Slotted Lisitano Coil
Authors: Kawai Yoshinobu , Komori Akio , Ikeda Hidehiko , Kishimoto Kengo , Murata Masayoshi , Uchida Satoshi
Published: February 2005

An ECR plasma is produced at relatively high pressures up to 25 mTorr with a slotted Lisitano coil 140 mm in diameter, and the radial distributions of plasma parameters are measured. It is found that the plasma is almost radially uniform even at pressures higher than 10 mTorr. Carbon films are formed on silicon wafers by introducing methane gas into the ECR plasma and the deposition rate is examined as a function of concentration of methane gas and substrate temperature. Furthermore, the physical properties of the films are analyzed by X-ray diffraction and Raman scattering. These results show that a slotted Lisitano coil is very useful for the ECR plasma CVD.
Fractal Structure of Electrochemically Polymerized Polypyrrole and Growth Process as Function of Monomer Concentration, Electrolyte Concentration and Applied Voltage
Authors: Fujii Masaharu , Saeki Yasuhide , Arii Kiyomitsu , Yoshino Katsumi
Published: February 2005

By the electrochemical method in the needle-circle electrode configuration, polypyrrole has been found to grow with two kinds of growth patterns; three-dimensional and two-dimensional growth patterns depending on the polymerization conditions such as condition of electrolyte and monomer and applied voltage. The conditions of pattern formation are found to be classified into three regions, 3-D growth, 2-D growth and 3-D+2-D growth regions. Three-dimensional growth model has been proposed from the growth condition. Influence of protuberance at the surface on the growth pattern by the electrochemical polymerization has been taken into consideration for the understanding of the patterns. The pattern of 3-D growth has been found to be fractal in the small scale region using the density correlation function.
Plasma CVD-Grown 10B-Enriched Boron Films for Si Neutron Detectors
Authors: Sato Noritada , Ishiwata Osamu , Seki Yasukazu , Ueda Atsushi
Published: February 2005

Hydrogenated amorphous boron (a-B:H) films were deposited on Si crystal substrates using DC glow discharge in B2H6 diluted to 1000 ppm in H2. We found that the rate of the deposition was about two times higher for 10B-enriched B2H6 than for natural B2H6. The deposition process was observed by optical emission spectroscopy of the DC glow. BH emission lines at 433.2 nm and 369.4 nm were strongly enhanced in the 10B-enriched B2H6/H2 compared with the natural B2H6/H2. This manifests an isotopic effect on the deposition rate of the a-B:H film. Concentrations of 10B, 11B and 1H in the films were analyzed by SIMS. The hydrogen content of the films was found to be 3.9 × 1023 atoms/cm3 from the thermal hydrogen release measured by gas chromatography. The 10B-enriched film was applied to construct a novel silicon neutron detector. It showed a satisfactory sensitivity for neutron detection.
New Alignment Sensors for Optical Lithography
Authors: Magome Nobutaka , Ota Kazuya , Nishi Kenji
Published: February 2005

Two alignment sensors, which will be used in half-micron and sub-half-micron lithography, have been newly developed and tested. Both were developed to improve overlay accuracy on some particular types of processed layers with which the current alignment system has problems. One has an incoherent illumination and bright field imaging system with the aim being to reduce scaling and random errors on Al layers. The other is an optical heterodyne sensor of which the aims are to reduce random errors on Al layers and increase the signal detecting capability for small step height marks. These sensors proved to be effective on most difficult layers, and they have practical throughput.
Silicon Membrane Mask Blanks for X-Ray and Ion Projection Lithography
Authors: Löchel B. , Chlebek J. , Grimm J. , Huber H.-L. , Macioßek A.
Published: February 2005

In the subquarter-micron range, X-ray lithography and demagnifying ion projection are promising printing techniques. For both methods special designed masks are needed which have to fulfil strong requirements including flatness, stabiltiy, defect density, transparency, and surface properties. In this paper we would like to demonstrate that silicon membrane based mask blanks are well suited to meet most of these demands. Furthermore, silicon as membrane material offers the advantage to make use of the experience in semiconductor process technology. A fabrication sequence has been developed, based on silicon epitaxial growing, clean-room compatible wet etching and anodic bonding techniques. Highly boron doped silicon layers with germanium as counter-dopant offer the possibility of stress engineering. An etching process on the base of KOH/IPA is applied in a clean-room environment to decrease the particle density during etching. A very comfortable bonding process for fixing silicon membranes on glass ring carriers was optimized and yieds super flat mask blanks. The application of this process and the results of the blank characterization are presented and discussed.
Ta Film Properties for X-Ray Mask Absorbers
Authors: Oda Masatoshi , Ozawa Akira , Ohki Shigehisa , Yoshihara Hideo
Published: February 2005

The properties of absorber materials for X-ray masks which can be patterned by a subtractive process are investigated. Highly pure film can be deposited using Xe rather than Ar as a working gas of RF sputtering. The stress of the Ta film can be controlled more precisely than either Re or W. Ta film deposited by RF sputtering is highly oriented, and has a high purity and a high density. Furthermore, its stress does not change even after annealing at 400°C.
High Etch Rate Modes in Microwave Plasma Etching of Silicon in High Magnetic Fields
Authors: Shindo Haruo , Hashimoto Tetsuro , Amasaki Fumitake , Horiike Yasuhiro
Published: February 2005

High etch rate modes in microwave plasma etching were studied in a high magnetic field regime. The Si etch rate clearly showed two modes in which the local maxima appeared in the magnetic fields around B
c=875 G and 2B
c, and the second maximum at 2B
c attained as high as 1500 A/min at 5 × 10-5 Torr of NF3 with 600 W input power. The first mode was ascribed to the ECR, but exactly to the upper hybrid resonance because the magnetic field at which the ion current showed the maximum decreased at higher electron density. A measurement of the microwave field inside the plasma demonstrated that the phase velocity of the microwave changed continuously with the magnetic field centered on 2B
c. Since this was consistent with the dispersion of the whistler wave, the second mode was ascribed to the whistler mode resonance.
Electron Spin Resonance Imaging Utilizing Localized Microwave Magnetic Field
Authors: Furusawa Masahiro , Ikeya Motoji
Published: February 2005

A method for two-dimensional electron spin resonance (ESR) imaging utilizing a localized microwave field is presented with an application of the image processing technique. Microwaves are localized at the surface of a sample by placing a sample in contact with a pinholed cavity wall. A two-dimensional ESR image can be obtained by scanning the sample in contact with the cavity. Some ESR images which correspond to distribution of natural radiation damages and paramagnetic impurities in carbonate fossils of a crinoid and an ammonite are presented as applications in earth science. Resolution of a raw ESR image is restricted by the diameter of the hole (1 mm). Higher resolution of 0.2 mm is obtained by using a deconvolution algorithm and instrument function for the hole. Restored images of a test sample of DPPH and of a fossil crinoid are presented.
The Reaction Sequence in the System Y2BaCuO5–BaCuO2–CuO for YBa2Cu3O7-δ Formation
Authors: Kim Hai Doo , Ko Jae Woong , Lee Soo Young , Chung Hyung Sik
Published: February 2005

The reaction sequence among 1 mole of Y2BaCuO5, 3 moles of BaCuO2 and 2 moles of CuO has been studied to provide fundamental understanding for the formation and disapperance of liquid phase in relation with YBa2Cu3O7-δ formation. Reaction between BaCuO2 and CuO starts to form a Ba–Cu–rich liquid phase at 900°C, which reacts with Y2BaCuO5 to give YBa2Cu3O7-δ. This reaction is dominant from 900°C to 920°C range and shows a transient nature. When a considerable amount of YBa2Cu3O7-δ is formed from the reaction, YBa2Cu3O7-δ starts to dissolve in Ba–Cu–rich liquid above 930°C and forms Y–Ba–Cu liquid phase. Upon cooling this Y–Ba–Cu containing the liquid phase crystallises between 940°C and 930°C.
Coercivity and Grain Boundary Morphology in Nd–Fe–B Sintered Magnets
Authors: Tsubokawa Yoshiyuki , Hirosawa Satoshi , Shimizu Ryuichi
Published: February 2005

The microstructure of Nd15Fe77B8 sintered permanent magnets has been investigated under a 400 kV high-resolution transmission electron microscope. With particular concern about the microstructural changes in the Nd–Nd2Fe14B interfaces, the effects of isothermal heat treatment at 870 K have been studied for a more comprehensive understanding of the coercivity-microstructure relationship in the Nd–Fe–B sintered magnets. The atomic-scale steps along the grain boundary can be observed in as-sintered samples. The steps disappear after heat treatment, and very flat interfaces are formed. This atomic-scale alignment at the grain boundary, therefore, is one of the factors affecting the coercivity of Nd–Fe–B sintered magnets.
Optical and Mechanical Properties of Hard Hydrogenated Amorphous Carbon Films Deposited by Plasma CVD
Authors: Yokoyama Haruki , Okamoto Masaki , Yamasaki Toshifumi , Takahiro Katsumi , Osaka Yukio , Imura Takeshi
Published: February 2005

Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma chemical vapor deposition from pure CH4 at a low pressure of the order of 10-4 Torr under a magnetic field to confine the plasma on negatively self-biased electrode. The reflectance spectra were measured in a wide range of 0.5–25 eV by using synchrotron radiation and a usual light source. The dielectric constants were determined by applying the Kramers-Kronig relation. Using an effective medium approximation, volume fractions of diamondlike, graphitelike and polymeric (polyethylene) components were derived. These results were compared with Raman scattering, hydrogen contents and Vicker's hardness of the asdeposited and annealed films.
Sensitivity Calibration of a VUV System by Branching Line Pairs of Highly Ionized Atoms
Authors: Mimura Mikio , Sato Kuninori , Akiyama Ryuichi , Otsuka Masamoto
Published: February 2005

Eight vacuum ultraviolet branching line pairs from C IV, O V, O VI, O VIII and Fe XXI are selected to perform in situ relative sensitivity calibration of a VUV monochromator installed on the JIPP T-IIU tokamak. Details of the behavior of these line pairs in a tokamak plasma are described and discussed. Relative sensitivity calibration in the wavelength region from 75 Å through 1230 Å is conducted by measuring the intensity ratios of these line pairs and by arranging them by the simple proportional allotment method.
Optimum Wavelengths in Solar-Blind UV Ozone Lidars
Authors: Maeda Mitsuo , Sibata Takashi , Akiyoshi Hideharu
Published: February 2005

A simulation code is developed to evaluate the signal-to-noise ratio in daytime observation with Mie lidar and differential absorption ozone lidar in the UV region. The UV spectrum of the solar background radiation is calculated on the basis of the radiation transfer equation. The cut off wavelength is 305–308 nm depending on the solar zenith angle. The theoretical results are compared with observed data. The optimum transmission wavelengths in Mie and ozone lidars are estimated at wavelengths of excimer-Raman lasers taking account of the solar-blind effect by stratospheric ozone, and the maximum detection range in the solar-blind lidar is discussed.
Nanostructure Fabrication by Scanning Tunneling Microscope
Authors: Baba Masakazu , Matsui Shinji
Published: February 2005

Direct writing deposition patterns of W metal and carbon, and etching patterns of Si are achieved by electron-beam-induced selective etching and deposition using a scanning tunneling microscope (STM-EBISED). These patterns have been obtained down to 50 nm in size with pulse modulating voltage. Furthermore, writing voltage dependencies of deposition and etching are discussed.
Numerical Study on Femtosecond Pulse Compression by Induced Phase Modulation with Group-Velocity Dispersion Effects
Authors: Yamashita Mikio , Torizuka Kenji
Published: February 2005

We report the practical evaluation of the compression in a dispersive single-mode fiber of a weak, femtosecond pulse by its interaction with a longer, intense, phase-modulating pulse. Our numerical analysis takes into account the group-velocity dispersion, unavoidable in real fibers, which affects the chirp linearity and hence the extent of compression attainable. We show that, even in the absence of matching of the pulse group velocities, a weak 50-fs pulse of any wavelength between 315 and 800 nm can be compressed from 18.5 to 6.8-fs by a 100-fs, 250-kW pulse at 630 nm. When the group velocities are matched, this compression is superior to that attainable by the less flexible, conventional self-phase modulation technique. In addition, it is shown that a weak, femtosecond near-infrared pulse propagating in the anomalous dispersion region can be compressed by fiber propagation alone, almost without being influenced by group velocity mismatching.
Zinc Oxide Thin Films Prepared by the Electron-Cyclotron-Resonance Plasma Sputtering Method
Authors: Manabe Yoshio , Mitsuyu Tsuneo
Published: February 2005

Zinc oxide (ZnO) thin films have been prepared by a sputtering deposition utilizing electron-cyclotron-resonance (ECR) plasma. An X-ray diffraction analysis indicated that the ZnO films were highly c-axis oriented. The electrical resistivity of ZnO films is as high as 2.5 MΩcm. It is confirmed that the ZnO films exhibit strong piezoelectricity. For a film-thickness-to-wavelength ratio h/λ of about 0.16, the effective electromechanical coupling coefficient k
2 for a surface acoustic wave was 0.7%, which is above 90% of the calculated value. The measured values of k
2 are comparable to those of the films fabricated by other conventional sputtering methods. In addition, optical emission spectroscopy was carried out during the deposition.
Vegard's Law in KFe(S1-xSex)2
Authors: Nishiyama Nobuaki , Lin Jin-hu , Okazaki Atsushi , Iwasaka Masakazu , Hirakawa Kazuyoshi
Published: February 2005

The lattice constant and chemical composition of a specimen of a mixed crystal can be determined simultaneously on the basis of well-established single-crystal X-ray diffractometry. From the data for various compositions of the system, the relation between the two quantities, which usually follows Vegard's law, can be established. An example of the application of this procedure is shown for the case of mixed crystals KFe(S1-x
Se
x
)2 (0≤x≤1). In contrast to a nonlinear relation to the nominal composition, the lattice constants are found to be linear to the composition when it is properly determined.
Noise of Optical Detection by Glow Discharge in the DC Magnetic Field: Phenomena by the Synchronizing Signals and Outside the Locking Range
Authors: Ueda Hiroyuki , Miyawaki Sawami , Iida Yukio , Morita Masanobu
Published: February 2005

In optical detection by a glow discharge with the application of a DC magnetic field, its noise power can be reduced by a synchronization effect, if a rf signal is injected into the discharge device. However, the noise power increases due to the phenomena outside the locking range. The spectrum distribution is examined quantitatively under conditions of oscillation.
Visibility Analysis of Laser Doppler Anemometry for Spherical Particles Smaller than Several Light Wavelengths
Authors: Takeo Takashi , Hattori Hajime
Published: February 2005

The signal visibility is analyzed for an optical-fiber dual-beam laser interferometer in the case where the scattered light from a spherical particle less than several light wavelengths in size is collected with an off-axis small circular aperture. The analysis is based on the Mie theory, and the signal visibility was calculated by means of multipole expansion of electromagnetic fields. Although computed visibility curves show rather oscillatory behavior and therefore seem to be less usable for particle sizing, they could be utilized for precise size measurement. Experimental results obtained by using silicon resin particles as test samples are in good agreement with the calculations.
Wind Profiling by a Conical-Scanning Time-Correlation Lidar
Authors: Matsui Ichiro , Sugimoto Nobuo , Sasano Yasuhiro , Shimizu Hiroshi
Published: February 2005

The presernt paper describes a new concept for a wind profiling technique using a conical scanning-lidar (laser radar). Measurement is based on a time correlation method using the pattern of aerosol and cloud distribution as a tracer. The direction of the laser beam is conically rotated about a vertical axis and lidar signals are collected in the preassigned directions. The analytical method is described as well as the results of field experiments.
Optimum Growth Conditions of GaAs(111)B Layers for Good Electrical Properties by Molecular Beam Epitaxy
Authors: Tsutsui Kazuo , Mizukami Hiroyuki , Ishiyama Osamu , Nakamura Satoshi , Furukawa Seijiro
Published: February 2005

Growth conditions of GaAs layers grown by molecular beam epitaxy (MBE) on (111)B-oriented GaAs substrates were optimized by surface morphology observation and Hall measurement. Good surface morphology was obtained by use of 1.5° off-oriented (111)B substrates. This paper reports for the first time that electron mobilities as high as those on (100) substrates can be obtained even at growth temperature as low as 530°C if the off-oriented (111)B substrates are used, whereas one higher than 600°C is necessary to obtain the same electron mobility on exactly (111)B-oriented substrates. MESFET's and Schottky diodes fabricated on the layer grown at the optimized condition show high electron mobility and suggest low concentration of defects.
Growth Characteristics and Electrical Properties of (100) CdTe Layers Grown on (100) GaAs by Low-Pressure Organometallic Vapor Phase Epitaxy
Authors: Yasuda Kazuhito , Ekawa Mitsuru , Matsui Nobuyuki , Sone Syuji , Sugiura Yoshiyuki , Tanaka Akikazu , Saji Manabu
Published: February 2005

The growth mechanism and electrical characteristics of (100) CdTe layers grown on (100) GaAs by low-pressure organometallic vapor phase epitaxy have been reported. The growth mechanism changed around the growth temperature of 400°C. Adduct pyrolysis dominated the growth below the temperature of 400°C. Above this temperature, a pyrolysis of DETe dominated the growth. High-quality p-type layers were obtained when the layers were grown thicker than 2 µm at 420°C. The hole density and the Hall hole mobility were in the ranges of 2.2-3.5×1015 cm-3 and 60–100 cm2/V·s, respectively. In contrast to this, the grown layer became semi-insulating when the thickness was less than 2 µm due to out-diffusion of Ga from the substrates. The double crystal X-ray rocking curve also showed a FWHM value of 155 arcsec at the thickness of 6 µm.
Mobility Profiles in Submicron WNx-BPLDD-GaAs MESFETs
Authors: Steiner Klaus , Uchitomi Naotaka , Toyoda Nobuyuki
Published: February 2005

The drift mobility profile in a submicron WN
x
-BPLDD (buried ptype buffer lightly doped drain region) GaAs MESFET with a highly doped buffer layer is evaluated using frequency-dependent admittance studies. A drift mobility maximum of 2300 cm2/Vs at a background carrier concentration level of 8×1017 cm-3 was determined. The investigations provide a convenient method for controlling transport properties in GaAs LSIs.
The Effect of Ejection Angle in Ion-Beam Sputter Deposition of Superconducting Amorphous Beryllium Film
Authors: Takei Koji , Maeda Yasushi , Beag Young Whoan , Shimizu Ryuichi
Published: February 2005

Ion-beam sputter-deposited amorphous Be films on silica substrates at different ejection angles are characterized by their superconducting properties. It is shown that the superconducting transition temperature of the film is varied by changing the ejection angle of the sputtered particles. To explain this, the role of incorporated oxygen and the contribution of highly energetic particles to the amorphous Be formation are discussed, taking account of both the anisotropic ejection of the direct recoiled target atoms measured by time-of-flight and the result of a Monte Carlo simulation of Be sputtering. The Monte Carlo simulation describes the angular distribution of the sputtered atoms with considerable success and is particularly helpful in revealing the contribution of energetic sputtered atoms of higher than 100 eV at low ejection angles.
Electrooptical Properties of Polymer Films Containing Nematic Liquid Crystal Microdroplets
Authors: Nomura Hideshi , Suzuki Sachio , Atarashi Yuji
Published: February 2005

Polymer films containing nematic liquid crystal microdroplets are useful for light modulation devices. Light scattering in these films is controlled by applied electric fields. These films were produced by cooling solutions of polymer in the isotropic phase of liquid crystal to temperatures below the clearing point (the nematic-phase-to-isotropic-phase transition temperature). In this process, sizes of microdroplets were regulated by controlling the rate of cooling. The relationship between the microdroplet size and electrooptical properties was investigated experimentally and theoretically.
Initial Growth Mechanism of GaAs on Si(110)
Authors: López Máximo , Ikei Takashi , Takano Yasushi , Pak Kangsa , Yonezu Hiroo
Published: February 2005

We report the initial growth mechanism of GaAs on Si(110) by molecular beam epitaxy. From in-situ reflection high-energy electron diffraction (RHEED) measurements we infer an initial two-dimensional growth mode. Streak RHEED patterns were observed up to about 20 Åthickness of GaAs epitaxial growth. With further deposition, extra spots appeared due to twins. We propose a model in which the twins are formed from antiphase domain boundaries.
Highly Beryllium-Doped and Lattice-Matched GaInAsP/InP Growth by Chemical Beam Epitaxy (CBE)
Authors: Uchida Toshi K. , Uchida Takashi , Mise Kazuaki , Koyama Fumio , Iga Kenichi
Published: February 2005

Highly Be-doped (>1019 cm-3) 1.45 µm-wavelength GaInAsP was grown by chemical beam epitaxy with a solid Be source. The hole concentration for both GaInAsP and InP was linearly related to the Be effusion cell temperature. In spite of high doping levels, neither obvious lattice mismatch nor surface degradation was observed. A stripe contact laser was also successfully fabricated using the results obtained.
Research and Development of a 100-kWp Photovoltaic Power Generation System for a Factory
Authors: Murozono Mikio , Kita Yutaro , Takakura Hideyuki , Hamakawa Yoshihiro
Published: February 2005

A 100-kWp photovoltaic power generation system was installed at a car battery manufacturing plant to supply dc output power to an initial-charge line of car batteries. It provides more than 120 MWh of annual output energy to the load, which corresponds to about 30% of the electric power consumed by the initial-charge line. The average daily output power from the photovoltaic (PV) array ranges from 290 kWh in winter and 430 kWh in summer. Output during the summer is increased by selecting the tilt angle of the array in 20 degrees. When proper operating voltage is selected during every month, output energy from the PV array is increased by about 10% as compared to the output under the rated operating voltage. The effects of auxiliary battery size and the employment of various kinds of modules in the array on the output is also discussed.
Optical Properties of Plasma-Deposited Silicon-Oxygen Alloy Films
Authors: Haga Koichi , Watanabe Hideo
Published: February 2005

Hydrogenated amorphous silicon-oxygen alloy films are prepared by r.f. glow discharge decomposition of a SiH4–CO2 gas mixture. The optical properties of these films are discussed in terms of oxygen content. The Lorentz-Lorenz theory is the best approximation to the dependence of the refractive index on the oxygen content. The existence of silicon-rich and oxygen-rich phases is probable in the amorphous alloy films.
Preparation of Bi0.7Pb0.3Sr1.0Ca1.0Cu1.8Oy High-Tc Superconductor by the Citrate Method
Authors: Hen Tian-Shyng , Chen Jiann-Ruey , Tseng Tseung-Yuen
Published: February 2005

A high-T
c superconductor with a nominal composition of Bi0.7Pb0.3Sr1.0Ca1.0Cu1.8O
y
was prepared by the citrate method. The solid precursor produced by the dehydration of the gel at 120°C for 12 h is not in the amorphous state as expected, but in a crystalline state. X-ray diffraction (XRD) peaks of nearly the same angular position as the peaks of high-T
c phase were observed in the precursor. After pyrolysis at 400°C and calcination at 840°C for 4 h, the (002) peak of the high-T
c phase was clearly observed. However, the volume fraction of the high-T
c phase did not increase significantly with sintering time. The zero-resistance temperature, T
c(0), was found to be 90.8, 95.6, and 98.3 K after sintering at 845°C for 10, 20, and 80 h, respectively. Experimental results suggest that the intermediate phase formed before the formation of the superconducting phases may be the most important factor in determining whether it is easy to form the high-T
c phase or not, because the nucleation barriers of the two superconducting phases may be altered by the variation of the crystal structures of those intermediate phases.
Ultrasonic Measurements of Molecular Motion in Polycarbonate Systems
Authors: Shirouzu Shigenori , Taki Seiji , Matsushige Kazumi
Published: February 2005

Ultrasonic spectroscopy was applied to measurements of molecular motions in polycarbonates from the glassy state to the molten state. To investigate the effects of molecular weight and structural modification, bisphenol-A-polycarbonate with two different molecular weights and one modified polycarbonate were employed. Some remarkable differences in molecular motions caused by these effects were observed.
Surface Topography of Ion-Etched Si Wafers Studied by Electron Microscopy
Authors: Yokota Yasuhiro , Hashimoto Hatsujiro , Song Minghui , Awaji Mitsuhiro
Published: February 2005

Wafers of 111 and 100 Si which had been mirror-finished and then scratched by #1500–3000 grit abrasive paper were ion-etched and their surfaces were investigated by SEM and cross-sectional high-resolution TEM techniques. Ion etching was carried out at incident angles of 75°, 65°, 55° at 5 kV Ar+ ion beam by rotating the specimens around the axis normal to the wafer surface. The etched surface of the mirroe-finished Si wafer stayed smooth for 4 hours of ion etching. After more than 4 hours of ion etching, round projections of 1–10 µm in diameter were generated. Cross-sectional observation showed small pyramidal protuberances of 5–20 nm in height on the 100 surface with facets of (111). No protuberances were observed on the 111 surface. The thickness of the amorphous layer formed on the 111 surface was different from the one on the 100 surface.
Preparation and Properties of Ge Microcrystals Embedded in SiO2 Glass Films
Authors: Hayashi Ryo , Yamamoto Masaki , Tsunetomo Keiji , Kohno Kenji , Osaka Yukio , Nasu Hiroyuki
Published: February 2005

Ge microcrystals were successfully doped into SiO2 glass films by the rf magnetron sputtering technique. The dependence of the average size of Ge microcrystals on substrate temperature and annealing time was discussed. The optical absorption spectra of Ge microcrystals clearly exhibited the blue shift compared with a bulk Ge crystal, which seems to be due to a quantum size effect.
A Time-Resolved Soft X-Ray Camera System with Rapid Data Processing and Its Application to a Pinched-Plasma Experiment
Authors: Hirano Katsumi , Nakajima Hiromasa , Kaneko Isao , Yamamoto Toshikazu , Shimoda Katsuji
Published: February 2005

A time-resolved soft X-ray camera system with dual pinholes is developed. The system consists of a soft X-ray pinhole camera and a detector combining an MCP (microchannel plate) and a phosphor screen. The X-ray image produced on the phosphor screen is acquired by a CCD (charge-coupled device) camera for rapid processing. The effective duration for the data acquisition was ∼3 ns and the spatial resolution was estimated to be 85 µm with a sufficient dynamic range. The soft X-ray emission in the collapse, unstable and disruption phases of a dense plasma focus was quantitatively observed by this system.
Analysis of Developed Pattern Profiles in X-Ray Lithography with Monochromatic X-Rays
Authors: Kawata Hiroaki , Tanaka Makoto , Murata Kenji
Published: February 2005

Developed pattern profiles in X-ray lithography, including various line edge degradation effects such as the spatial spreading of photo and Auger electrons, the penumbra and the Fresnel diffraction effects with monochromatic X-ray beams of Mo Lα and Al Kα, are simulated. The developed pattern profiles are degraded by the penumbra effect to a larger extent than by the diffraction effect when patterns with a size of a quarter micron are fabricated. However, Fresnel diffraction has an appreciable degradation effect when patterns with a size of 100 nm are fabricated. The results show that a contrast of 1:1/9, which is defined as the ratio of the X-ray intensities through the opaque region of the mask to that through the clear region, is high enough to make line-and-space patterns of 200 nm period with the Al Kα X-ray source.
An Electron Spin Resonance System for In-vivo Human Tooth Dosimetry
Authors: Ishii Hiroshi , Ikeya Motoji
Published: February 2005

An electron spin resonance (ESR) dosimetry system for an in-vivo human tooth has been developed to measure, without extraction, the cumulative radiation dose in a tooth. The system consists of a TE102 cavity with an aperture at the end plate, a Nd–B–Fe (Neomax) oral magnet and a commercial ESR spectrometer. The front molar is attached to the aperture of the cavity to detect radicals created by radiation in the tooth enamel. Optimum dosimetry conditions were investigated using an extracted human tooth.
Novel Aspects of the Optogalvanic Effect in the CO2 Laser Medium
Authors: Tachikawa Maki , Murakami Hiromi , Shimizu Fumiko O. , Shimizu Tadao
Published: February 2005

Dynamic properties of the optogalvanic signal in the CO2 laser medium are investigated as functions of the modulation frequency of the incident laser beam and the gas pressure. It is determined that a positive optogalvanle effect occurs in the gain medium when the gas pressure is sufficiently low, while a negative optogalvanic effect occurs at higher gas pressures. The mechanism of the signal inversion is explained by the competition between the collisional relaxation process and the spontaneous emission from the upper laser level.
Synchrotron Radiation Section Topography with Extremely High-Order Reflection and Its Application to the Characterization of MCZ-Silicon Crystals
Authors: Iida Satoshi , Takeno Hiroshi , Sugita Yoshimitsu , Kawata Hiroshi
Published: February 2005

Section topographs of MCZ-Si crystals annealed at low temperatures have been taken with high-order reflections up to 18 18 0 and 24 0 0 using 0.4 Å synchrotron radiation. High sensitivity of high-order reflection to the lattice strain has been demonstrated and used to characterize the small lattice strain which could not be detected by conventional section topography with low-order reflections.
Neural-Network Model of Induction Processes in the Way of Thinking by Using Random Excitation Patterns of Neural Elements
Authors: Agu Masahiro , Yamanaka Kazuo
Published: February 2005

Based on the viewpoint that inductive prediction is regarded as an evolution process of information in the brain, the process of induction is modeled as a random selection procedure of plausible hypothesis under given data, by using random excitation patterns of probabilistic neural elements. The joint probability P(H, D) of hypothesis H and datum D is realized as the statistical distribution of the fluctuating excitation patterns of the neural network. The posterior probability P(H|D) can be estimated by selecting the fluctuations consistent with the observed datum D among those excited spontaneousely in the network. The estimation of a prototype pattern from its perturbed or incomplete patterns is treated as a typical induction problem, whose simple computer simulatin is given.
Infrared Spectroscopic Study of Mercury-Sensitized Photo-CVD Silicon Oxide
Authors: Lan W. H. , Tu S. L. , Yang S. J. , Huang K. F.
Published: February 2005

Silicon oxide (SiO
x
) films deposited on a silicon wafer by the Hg–sensitized photochemical vapor deposition (photo-CVD) method using silane (SiH4) and nitrous oxide (N2O) under the illumination of low pressure mercury lamps were investigated. While increasing the partial pressure ratio of SiH4 to N2O, an increasing-maximum-decreasing behavior of the deposition rate and an increasing shape behavior of the refractive index have been observed. Infrared (IR) spectra analysis showed that the films were SiO2-like in the low silane partial pressure region and were SiO-like in the high silane partial pressure region. The 450 cm-1 absorption peak was good evidence for differentiating these two types of films. The infrared absorption peak due to Si–H stretching can also be eliminated after the N2 annealing treatment.
Mechanism of GaAs Selective Growth in Ar+ Laser-Assited Metalorganic Molecular Beam Epitaxy
Authors: Sugiura Hideo , Yamada Takeshi , Iga Ryuzo
Published: February 2005

Ar+ laser-assisted epitaxy of GaAs, GaP, and GaAsP is studied. Laser irradiation during growth enhances growth rates of the three kinds of films. Growth rates of the laser-irradiated areas are the same and remain constant in the substrate temperature range 400–550°C, irrespective of the direct or indirect bandgap semiconductors. Laser beams of 500 mW irradiate a quartz ampule filled with triethylgallium molecules, causing white dots to form on the inside walls of the ampule. These results strongly suggest that the mechanism of the growth rate enhancement is photolytic decomposition of triethylgallium adsorbed on the substrate.
Stretched Exponential Capacitance Transient and Emission Rate Spectrum of DX-Centers
Authors: Yonekura Hideaki , Arai Takashi , Morimoto Jun , Miyakawa Toru
Published: February 2005

Consistency is studied between two expressions for nonexponential capacitance transients due to DX-centers in Al
x
Ga1-x
As:Sn: the recently proposed stretched exponential decay form and the emission rate spectrum. It is found that (1) capacitance transients can be approximated by a stretched exponential with a parameter β monotonously increasing with temperature, and (2) the log-normal distribution of the emission rate spectrum derived from this expression is not inconsistent with the model of a deep center with a broadening Δ
E in activation energy. The magnitude of Δ
E∼20 meV estimated from temperature dependence of β is in good agreement with our previous results.
X-Ray Photoelectron Spectroscopy of Micrometer-Size Surface Area Using Synchrotron Radiation
Authors: Ninomiya Ken , Hirai Yasuharu , Momose Atsushi , Aoki Sadao , Suzuki Keizo
Published: February 2005

An axisymmetric Wolter type I mirror was used at a synchrotron radiation beamline in order to produce a focused X-ray beam with a photon energy of 150 eV. An FWHM (full width at half maximum) of 4 µm was achieved in the beam intensity profile. A Si(2p) XPS spectrum was then observed for a Si sample with this focused beam. This is the first microscopic XPS measurement in the micrometer range that has been achieved using a Wolter type mirror.