bluuebunny/crossref_metadata_2025 huggingface dataset:
A Versatile Photoelastic-Modulator Driver/Controller
Authors: Hayashi Shigeo
Published: February 2005

A PEM driver that is based on the principle of the phase locked loop has been built. The power can be applied at any phase angle to the PEM optical element, allowing us to measure its frequency characteristics easily since the phase angle is related directly to the frequency offset from the resonance frequency. No discernible drift in the drive voltage and the power phase angle has been observed. With the phase angle set exactly to zero, the driver is found to be four to five times more efficient than conventional ones, and rapid wavelength scanning is demonstrated.
Effects of Ferrite Magnetic Wedges and Condenser Capacity on Torque Characteristics of a Capacitor Motor
Authors: Hasegawa Siichi , Kaga Akio
Published: February 2005

A split-phase capacitor motor is used to drive such domestic loads as household refrigerators and other home electric appliances. This type of motor, however, is usually operated by producing alternating (pulsating or oscillating) torque. In this study, ferrite magnetic wedges have been inserted into stator slot openings of a capacitor motor, and some experimental investigations have been developed to reduce the alternating torque of the motor. With wedging ferrite materials, the amplitude of alternating torque has been decreased to decrease power losses and to increase motor efficiency. When the capacity of the running condenser was exchanged to find suitable operating conditions, the amplitude of alternating torque was likely to decrease, but the increase of condenser capacity has led to increases in circuit currents and power losses. Accordingly, it has been found that there could be an optimal condenser capacity for improving the motor characteristics.
Defect-Induced Non-Linear Properties of Silica-Based Fibres
Authors: Poumellec B. , Gabriagues J. M. , Fevrier H.
Published: February 2005

Some optical fibres, pumped by a Nd:YAG laser, exhibit stimulated emission bands which cannot be accounted for by third-order non-linear processes. Our interpretation is based on stimulated fluorescence of structural defects.
Application of the Multiquantum Well (MQW) to a Surface Emitting Laser
Authors: Uenohara Hiroyuki , Koyama Fumio , Iga Kenichi
Published: February 2005

The threshold current density of a surface emitting laser using the multiquantum well (MQW) is theoretically estimated to be about 60% that of a surface emitting laser with a bulk active layer. MQW structures with 10∼100 wells were grown by MOCVD and characterized by forming stripe lasers. A GaAlAs/GaAs MQW surface emitting laser was fabricated and the first lasing operation by current injection at 77 K under pulsed condition was obtained.
Electric Probe Measurements in an ECR Plasma CVD Apparatus
Authors: Shirai Kouun , Iizuka Takashi , Gonda Shun-ichi
Published: February 2005

Plasma diagnostics in the reaction zone of electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) apparatus have been made by the Langmuir probe technique. In addition to a conventional probe analysis, further investigations of the ion saturation current, the floating potential and the electron energy distribution lead to obtaining reliable plasma parameters. For the plasma density, the effect of the magnetic field is taken into account according to Dote's theory. The pressure dependence of the electron temperature can be explained in terms of the balance between the generation and loss of charged particles. The influence of the magnetic field on the electron temperature can be taken into account through this particle balance.
Resistivity Correction Factor for the Four-Probe Method: Experiment II
Authors: Yamashita Masato , Yamaguchi Shoji , Nishii Toshifumi , Kurihara Hiroshi , Enjoji Hideo
Published: February 2005

Experimental verification of the theoretically derived resistivity correction factor F is presented. Factor F can be applied to a system consisting of a disk sample and a four-probe array. Measurements are made on isotropic graphite disks and crystalline ITO films. Factor F can correct the apparent variations of the data and lead to reasonable resistivities and sheet resistances. Here factor F is compared to other correction factors; i.e. F
ASTM and F
JIS.
Direct Observations of the Process of Growth of YBa2Cu3O7-δ Crystals from the Melt by Means of Optical Microscopy
Authors: Hoshizaki Hiroki , Kawabata Sanemasa , Kawahara Nobuaki , Enami Hiroyoshi , Shinohara Toshiyuki , Imura Toru
Published: February 2005

The melting and growth process of Y–Ba–Cu–O crystals was directly observed by means of optical microscopy for the first time, and after the solidification, typical regions were analyzed by means of micro-X-ray diffraction analysis and electron probe microanalysis. The observed results not only had a good correspondence to the phase diagrams suggested by the previous workers but also yielded much information about the place, shape, and velocity in the crystal growth process.
Fundamental Lateral-Mode Operation in Broad-Area Lasers Having Built-in Lenslike Refractive Index Distributions
Authors: Nakatsuka Shin'ichi , Tatsuno Kimio
Published: February 2005

High power fundamental lateral-mode operation is achieved in an (AlGa)As broad-area laser diode. This diode has built-in lens-like refractive index distributions in the stripe. These distributions effectively suppress higher order lateral-mode generation by expanding the laser beam in the direction parallel to the junction. As a result, fundamental lateral-mode operation of up to 80 mW for CW operation is attained with this laser.
Branching Angle Tuning of a Multi Step Ion-Exchanged Two-Mode-Interference Wavelength-Dvision Multi/Demultiplexer in Glass
Authors: Chung Y. , Han K. G. , Kim S. H. , Choi S. S.
Published: February 2005

An integrated optical wavelength-division multi/demultiplexer based on wavelength dependent two-mode interference is fabricated on glass by the multistep ion exchange method. Dual-channel multi/demultiplexers with different branching angle are fabricated, and it is found that the transmission characteristic curves can be parallelly shifted by 45–125 nm/degree. The devices are designed for the wavelength range λ=590–630 nm. Channel separations are as low as 14 nm, and the on/off ratio is greater than 20 dB.
Aperiodic Conductance Fluctuations in a Narrow GaAs/AlGaAs Wire
Authors: Mizuno Masahiro , Ishibashi Koji , Noh Sam Kyu , Ochiai Yuichi , Aoyagi Yoshinobu , Gamo Kenji , Kawabe Mitsuo , Namba Susumu
Published: February 2005

We have studied quantum transport properties of a narrow GaAs/AlGaAs wire fabricated by electron beam lithography by means of the magnetoresistance (MR) and its Fourier transform. Magnetofingerprints and universal conductance fluctuations are observed at the low-temperature MR. It is found that decay of aperiodic fluctuations, which is observed in the low-frequency side of the Fourier spectra of the MR, shifts toward low frequencies as magnetic field increases.
Compositional Disordering of In0.53Ga0.47As/InP Multiquantum Well Structures by Repetitive Rapid Thermal Annealing
Authors: Miyazawa Takeo , Iwamura Hidetoshi , Mikami Osamu , Naganuma Mituru
Published: February 2005

In0.53Ga0.47As/InP multiple-quantum well (MQW) structures were disordered using a dopant-free technique for the first time. MQW disordering was accomplished by deposition of a Si3N4 cap followed by repetitive rapid thermal annealing (RRTA) at 800°C. The optical transmission spectrum for the capped region is blue-shifted by 84 nm relative to a capless region in the 1.5 µm wavelength region. Such a large blue-shift could not be achieved by conventional rapid thermal annealing. The disordered region extends at least 1.7 µm into the MQW structures.
Reactive Ion Etching of Copper Films in SiCl4 and N2 Mixture
Authors: Ohno Kazuhide , Sato Masaaki , Arita Yoshinobu
Published: February 2005

Reactive ion etching of Cu films in SiCl4 and N2 is proposed for the fabrication of copper interconnection lines in LSIs. Cu films can be etched using a wafer heated to at least 250°C. Adding N2 to SiCl4 has two advantages. One is that it prevents the etching rate of Cu between narrow pattern spaces from decreasing because it removes organic material on Cu films near resist patterns. The other is that it forms protective films such as SiN on the side walls of Cu patterns and prevents side etching. The side wall taper is controlled by changing the N2 flow percentage.
Y-Line Emission and Lattice Relaxation in MBE-ZnSe and -ZnSSe on GaAs
Authors: Saraie Junji , Matsumura Nobuo , Tsubokura Mitsutaka , Miyagawa Kazuhiro , Nakamura Nobuhiro
Published: February 2005

The Y-line emission in photoluminescence spectra at 11 K was studied in MBE-ZnSe and -ZnSSe (up to a sulfur content x=0.13) on GaAs. Compared with X-ray diffraction data, the Y-line seems to relate to misfit dislocations, and thus seems a good measure for checking lattice relaxation in ZnSe and ZnSSe epilayers with a sulfur content x<0.04. The critical thickness h
c determined from the Y-line is compared with the theoretical predictions of Matthews and Blakeslee. No Y-line was observed for sulfur content x>0.05, the reasons for which are discussed.
Resonant Tunneling Characteristic in InGaAs/InAlAs MQW Diodes with Si-Doped Quantum Wells
Authors: Kawamura Yuichi , Asai Hiromitsu , Wakita Koichi , Mikami Osamu , Naganuma Mitsuru
Published: February 2005

A clear negative differential resistance (NDR) due to the resonant tunneling effect is observed in InGaAs/InAlAs multiple quantum well (MQW) diodes with Si-doped quantum well structures at room temperature. The NDR appears in the wide voltage region. It is found that the peak current of the NDR for undoped well structures decreases with increasing temperature, while that for Si-doped well structures increases with increasing temperature, leading to the observation of the NDR at room temperature.
Electron Energy Loss Spectroscopy on Oxygen K-Edge Fine Structure of YBa2Cu3Oy Containing Dopants (La, Ca, Co)
Authors: Shindo Daisuke , Hiraga Kenji , Tokiwa Ayako , Soga Takeshi , Hojou Kiichi , Furuno Shigemi , Otsu Hitoshi , Nakajima Satoru , Hirabayashi Makoto , Kikuchi Masae , Syono Yasuhiko
Published: February 2005

The fine structures of the oxygen K-edge in the Y-Ba-Cu-O system, in which hole content was controlled by reducing the oxygen content and doping elements (La, Ca and Co), were investigated by electron energy loss spectroscopy (EELS). When Ba(+2) and Y(+3) were replaced by La(+3) and Ca(+2), respectively, the oxygen content of the sample changed and the peak corresponding to the hole state near the Fermi energy sensitively changed with the average hole content. When Cu(+2) was replaced by Co(+3), T
c decreased drastically and the peak at the oxygen K-edge shifted to higher energy.
Melt-Textured Growth of Superconducting YBa2Cu3O7-x Phase on (100) Plane of MgO
Authors: Jang Hyun M. , Moon Kil W. , Baik Sunggi
Published: February 2005

Melt-textured growth of the YBa2Cu3O7-x
phase from a supercooled melt created locally aligned, needle-shaped grains of the orthorhombic 1-2-3 phase. However, a strong wettability of the Cu-rich liquid phase (BaCuO2+CuO) on the (100) plane of MgO hindered complete formation of the 1-2-3 phase, and we observed the phase separation of the 2-1-1 phase (Y2BaCuO
x
) and Cu-rich precipitates from the stoichiometric melt of YBa2Cu3O7-x
.
Novel Ferroelectric Liquid Crystals with Very Large Spontaneous Polarization
Authors: Nakauchi Jun , Uematsu Mioko , Sakashita Keiichi , Kageyama Yoshitaka , Hayashi Seiji , Ikemoto Tetsuya , Mori Kenji
Published: February 2005

Several ferroelectric liquid crystals derived from a new optically active (2S, 5R)-2-hydroxy-5-hexyl-δ-valerolactone have been synthesized, and their mesomorphic and ferroelectric properties have been investigated. Very large spontaneous polarization (P
s) has been observed in these compounds, one of which shows an extremly large P
s value: as high as 320 nC/cm2.
New Ferroelectric Liquid Crystal with Large Spontaneous Polarization
Authors: Yoshizawa Atsushi , Nishiyama Isa , Fukumasa Mitsuo , Hirai Toshihiro , Yamane Mamoru
Published: February 2005

We report the preparation of new ferroelectric liquid crystals, 4-(2-methylalkanoyl)phenyl 4'-alkyloxybiphenyl-4-carboxylates, and the measurements of their physical properties. The dependence of the magnitude of the spontaneous polarization on the alkyl chain length is observed. 4-(2-Methyloctanoyl)phenyl 4'-octyloxybiphenyl-4-carboxylate shows extremely large spontaneous polarization, 293 nC/cm2 (at 62°C) and 403 nC/cm2 (at 39°C).
The Enhanced Diffusion of Low-Concentration Phosphorus, Arsenic and Boron in Silicon during IR-Heating
Authors: Ishikawa Yutaka , Yamauchi Kazuyuki , Nakamichi Ichiro
Published: February 2005

The diffusion of P, As and B in silicon during IR-heating has been investigated quantitatively under low-concentration conditions. A spin-on source was used for the diffusion of the dopants. The diffusion coefficient was determined by fitting the measured concentration profile to the complementary error function. Enhanced diffusion was obtained for these three impurities. The degree of the enhancement became larger in the order of As, P and B. The cause of the enhancement was found to be the generation of excess self-interstitials during IR-heating.
Characterization of Copper Indium Diselenide Thin Films by Raman Scattering Spectroscopy for Solar Cell Applications
Authors: Yamanaka Satoshi , Konagai Makoto , Takahashi Kiyoshi
Published: February 2005

Compositional characterization of CuInSe2 thin films by Raman scattering spectroscopy for solar cell applications was proposed. It was shown that Raman scattering spectroscopy is a promising method for the characterization of CuInSe2 film composition (especially Cu/In ratio). It was also found by using Raman scattering spectroscopy that the In-rich CuInSe2 on Cu-rich p+-CuInSe2 bilayer structure gives high-photovoltaic performance, and a conversion efficiency of 8.16% for CdS/CuInSe2 solar cells was achieved by optimizing such a bilayer structure.
Annealing Effects on Transition Temperature of Superconductiong Bi-Sr-Ca-Cu-O Films after Ion Irradiation
Authors: Hoshiya Taiji , Takamura Saburo , Aruga Takeo , Kobiyama Mamoru
Published: February 2005

The effect of annealing after irradiation on the transition temperature is studied for polycrystalline Bi-Sr-Ca-Cu-O films irradiated by He ions at room temperature. The temperatures of the out-diffusion and the in-diffusion of oxygen are obtained by annealing in air and a vacuum. There is a large recovery stage around 200∼500°C on annealing in air after irradiation. The 110 K phase grows remarkably upon annealing at 600°C after irradiation.
Preparation of Pure 80 K Superconductors in the Bi-Sr-Ca-Cu Oxide System
Authors: Ono Akira
Published: February 2005

Pure compounds of Bi2(Bi, Sr, Ca)3Cu2O
y
(y=8.65–8.86) were prepared in air and studied in order to elucidate the close relationships among T
c, Bi content, quenching temperature and lattice constants. It was found that formation of the pure superconductor strongly depended on the Bi content and Ca/Sr ratio. A considerable change of T
c took place with a slight change in oxygen number y which was below 0.04. To achieve the highest T
c, the oxygen number y should be controlled to an appropriate value which depends on the Bi content.
Synthesis and Decomposition of the High-Tc Phase of a Pb-Doped Bi-Sr-Ca-Cu-O Superconductor
Authors: Suzuki Yasunao , Inoue Tetsuo , Hayashi Shigeyuki , Komatsu Hiroshi
Published: February 2005

The processes of synthesis and decomposition of the high-T
c phase of a Pb-doped Bi-Sr-Ca-Cu-O superconductor were studied in terms of the sintering temperature and time. It was found that the high-T
c phase incongruently melted and decomposed into the low-T
c phase and liquid around 870–880°C. Ca-rich needlelike crystals were newly formed from the liquid (partially melted portion).
LEED-AES Observations of 7 K- and 80 K-phase Bi-Sr-Ca-Cu-O Single Crystals
Authors: Kishida Satoru , Tokutaka Heizo , Fujimoto Hiroshi , Nishimori Katsumi , Ishihara Naganori
Published: February 2005

LEED and AES observations were made on the clean surfaces of 7 K- and 80 K-phase Bi-Sr-Ca-Cu-O single crystals. It is clear that the surface structure of the 7 K-phase crystal is the same as that of the 80 K-phase crystal. The clean surfaces of the specimens are very stable without any adsorption of CO2 and O2 gases. However, in light of the fact that the intensity of carbon becomes greater in the AES spectrum after baking a chamber, the active carbon compounds are thought to be adsorbed on the clean surfaces of the 7 K- and 80 K-phase single crystals.
Preparation of Porphyrin Thin Films Using the Micelle Disruption Method and Their Photoresponses
Authors: Takeda Kazuhiko , Harima Yutaka , Yokoyama Seiichiro , Yamashita Kazuo
Published: February 2005

Thin films of eight different porphyrins were successfully prepared on ITO electrodes by means of the electrolytic micelle disruption (EMD) method. Photoelectrochemical properties of these porphyrin electrodes were investigated in an I
3
-/I
- redox solution. The photocurrent quantum yield for the (5, 10, 15, 20-tetraphenylporphyrinato)zinc(II) (ZnTPP) electrode prepared by the EMD method reached 12.6%, which was 20 times greater than that for the ZnTPP electrode prepared by the conventional vacuum sublimation technique.
Y2BaCuO5 as a Substrate for YBa2Cu3Ox
Authors: Dorris S. E. , Lanagan M. T. , Moffatt D. M. , Leu H. J. , Youngdahl C. A. , Balachandran U. , Cazzato A. , Bloomberg D. E. , Goretta K. C.
Published: February 2005

Bulk Y2BaCuO5 has been found to have a higher stiffness but a lower thermal expansion than YBa2Cu3O
x
. Y2BaCuO5 exhibits semiconducting behavior at room temperature. Composite tapes consisting of layers of Y2BaCuO5 and YBa2Cu3O
x
cracked upon sintering because of large differences in shrinkage rate. Addition of 15 volume % Ag to the YBa2Cu3O
x
strengthened the material and prevented cracking.
Laser Ignition of Premixed Methanol/Air on a Slot-Nozzle Burner
Authors: Koda Seiichiro , Shimizu Hideaki , Koinuma Tsutomu
Published: February 2005

Laser ignition of premixed methanol/air was performed on a slot-nozzle burner. The minimum absorbed laser fluence for successful ignition per unit volume absorbing the laser energy was determined. The minimum absorbed laser fluence was found to increase monotonically with an increase in the equivalence ratio studied. This trend was successfully explained by means of a kinetic model and was regarded as a notable feature of laser ignition in which heat and radical species are simultaneously supplied through the initial photochemistry.
Solid-State Glucose Sensor Using LaF3-Based Transducer
Authors: Miura Norio , Matayoshi Naoko , Yamazoe Noboru
Published: February 2005

A new-type glucose sensor using a LaF3-based transducer was investigated as the first example of a solid-electrolytecoupled biosensor. The sensor element was composed of the following electrochemical cell: (reference electrode) Sn+SnF2∣LaF3∣Pt-glucose oxidase (sensing electrode). The e.m.f. of the sensor cell was found to vary logarithmically with a change in glucose concentration in the range from 2×10-5 to 1×10-2 M in a phosphate buffer solution of pH 6.9. The 90% response time to 3×10-2 M glucose was about 15 s at 30°C. The sensitivity of the sensor to glucose was fairly stable for the test period of about 30 days.
Analysis of GaAs MOMBE Reactions by Mass Spectrometry
Authors: Ohki Yoshimasa , Hiratani Yuji , Yamada Masamichi
Published: February 2005

The thermal decomposition of trimethylgallium (TMG) under metal-organic molecular beam epitaxy (MOMBE) conditions is studied by mass spectrometry. For the first time, it is observed that the amount of Ga-containing species desorbed from the GaAs surface decreases above 350°C. Measurements on CH3, CH4 and C2H6 indicate that TMG pyrolyzes by releasing methyl radicals. The amount of Ga-containing species desorbed from the SiO2 surface does not show a steep decrease up to 530°C, which indicates that no thermal decomposition occurs on SiO2. This explains the mechanism of selective epitaxy in MOMBE.
Photoluminescence Study of Type I and Type II GaAs/GaP Strained-Layer Superlattices Grown on GaAs Substrates
Authors: Armelles Gaspar , Recio Miguel , Meléndez Juan , Ruiz Ana , Briones Fernando , Khirouni Kamel , Barrau Jean , Lauret Nicole
Published: February 2005

We studied the photoluminescence emission from short-period GaAs-GaP strained-layer superlattices grown by Atomic Layer Molecular Beam Epitaxy (ALMBE) on GaAs substrates. The observed peaks as functions of the temperature, excitation power and design parameters (period and strain accommodated in the constituent layers) were studied. Amongst the samples under study we found spatially direct (type I) and indirect (type II) superlattices. Good agreement between experiments and calculations were found for a conduction-band offset of 0.4 eV.
Formation of the High-Tc Phase of Bi1-xPbxSr0.90Ca1.10Cu1.50Oy (0≦x≦0.05)
Authors: Iwai Yutaka , Takata Masasuke , Yamashita Tsutomu , Ishii Mamoru , Koinuma Hideomi
Published: February 2005

A seeding process was applied to prepare the high-T
c phase of Bi-based superconducting oxides with small amount of PbO. The application of the seeding process enables us to prepare the high-T
c phase more easily. The lattice constants decreased with increasing PbO content. The temperature dependence of resistivity was also examined.
The Influence of Fluorine Addition on the Crystal Structure and Electrical Properties of a YBa2Cu3O7-δ Oxide Superconductor
Authors: Fukushima Kensuke , Kurayasu Hirofumi , Tanaka Toshiro , Watanabe Seiichi
Published: February 2005

The influence on crystal structure and electrical properties of fluorine ions replacing oxygen ions in the YBa2Cu3O7-δ lattice is observed by mixing BaF2 powder and calcining at 1193 K. Within a small limit, the increase of BaF2 addition gives a sharp rise to the lattice constant of the c-axis while excess addition over the limit causes almost no change in the lattice constant. This suggests that BaF2 dissolves in solid solution with the minute solubility limit which is estimated to be around x=0.15 in the form of YBa2Cu3O7-δ
F

x
. The zero-resistivity transition temperature is the highest at x=0.10.
Solution-Phase Preparation and Characterization of Bi1.6Pb0.3Sb0.1Ca2Sr2Cu3O10
Authors: Spencer N. D. , Murphy S. D. , Shaw G. , Gould A. , Jackson E. M. , Bhagat S. M.
Published: February 2005

We report a carbonate coprecipitation technique for preparing Bi1.6Pb0.3Sb0.1Ca2Sr2Cu3O10 samples. X-rays, microwave absorption and magnetic measurements show that the material is nearly single phase with T
c≃106 K. The presence of antimony appears to accelerate the formation of -2223 from the -2122.
Thomson Scattering Diagnostics of a Discharge-Pumped Excimer Laser
Authors: Yamakoshi Hideo , Kato Mitsuo , Uchino Kiichiro , Iwata Tsunehisa , Masuda Mitsuharu , Muraoka Katsunori , Maeda Mitsuo , Akazaki Masanori
Published: February 2005

The electron velocity distribution function is the key parameter for understanding chemical kinetics in plasmas of discharge-pumped excimer lasers. Local and unambiguous determination of the parameter is presently only possible by the Thomson scattering, and this letter describes the first observation of the Thomson scattering signals from ruby laser light from an excimer laser. The results revealed otherwise inaccessible structure of the electron temperature, such as an increase of the temperature when the buffer gas was changed from helium to neon.
Luminescence of Pyrene-Doped Amorphous Silica Glasses Prepared by the Sol-Gel Method
Authors: Takahashi Yoshihiro , Kitamura Takashi , Uchida Kenji , Yamanaka Takaya
Published: February 2005

Pyrene-doped amorphous silica glasses were prepared by the sol-gel method. The optical properties of these pyrene-doped amorphous silica glasses, such as the absorption spectra, the excitation spectra, the fluorescence spectra, and the fluorescence decay time, were measured and compared with those in ethanol solution. From the dependence of these optical properties on the pyrene dopant concentration, the degree of molecular dispersion in the amorphous silica glasses is discussed.
The Dependence of Light Intensity on Surface Morphology and Impurity Incorporation for ZnSe Grown by Photo-Assisted MOVPE
Authors: Yasuda Takashi , Koyama Yoshihisa , Wakitani Jun , Yoshino Junji , Kukimoto Hiroshi
Published: February 2005

We investigated the surface morphology and impurity incorporation for ZnSe epitaxial layers grown on GaAs substrates by MOVPE under light irradiation of different intensities. The surface morphology tends to become rough with increasing irradiation intensity. The incorporation of residual-donor impurities, probably chlorine from the source material of dimethylzinc, is also enhanced with irradiation intensity. The optimum growth conditions for obtaining high-quality layers at acceptable growth rates are presented.
Diamond Synthesis Suppressing the Thermal Decomposition of Methane in a Hot-Filament CVD
Authors: Aikyo Hiroyuki , Kondo Ken-ichi
Published: February 2005

Diamond films have been obtained by a new hot-filament CVD method in which CH4 is dccomposed mainly by abstraction reaction with atomic hydrogens. The film obtained by this method was compared with that obtained by the method that involves the thermal decomposition of CH4 near a filament. The quality of the former was better in crystallinity and amount of amorphous carbon but slightly lower in deposition rate than that by the latter method. It is suggested that the buoyancy flow induced near the hot filament affected the transport of reactant species even at 100 Torr.
Photon Storage Ring
Authors: Yamada Hironari
Published: February 2005

The proposed photon storage ring (PhSR) is composed of an electron storage ring (ESR) and a group of mirrors surrounding the electron orbit. The ESR in this case is of a type having no straight sections. In this system, synchrotron radiations are reflected back by the mirror to intersect the electron orbit again, and are consequently accumulated within the mirror. The PhSR functions like an undulator having an infinite number of periods, and thus specific wavelengths are enhanced. The wavelength is selected by the mirror radius regardless of the electron energy as long as the electron orbit curvature is kept unchanged. The generated synchrotron radiations are fully extracted through a simple opening on the mirror surface. A strong magnetic field can be introduced without any deterioration of the interference effect, which allows the radiation yield to be increased. A conceptual design of such a PhSR is described in this article.
Zn Diffusion into InP Using Dimethylzinc as a Zn Source
Authors: Wada Morio , Seko Masahito , Sakakibara Katsutoshi , Sekiguchi Yoichi
Published: February 2005

A new method of Zn diffusion into InP using dimethyl-zinc(DMZ) as a Zn source is described. This diffusion method provides precise control over both diffusion depth and Zn concentration, and is easier to use and gives highly reproducible results. Diffusions were carried out from 400 to 570°C with the Zn surface concentration of 1017 to 1018 cm-3, and diffusion depth of 0.2 to 2 µm. The diffusion profiles were measured by SIMS analysis and electrolytic etching with simultaneous C-V measurement.
New Deep-Level Photoluminescence Bands of Homoepitaxial CdTe Films Grown by Metalorganic Chemical Vapor Deposition
Authors: Fujii Satoshi , Terada Toshiuki , Fujita Yasuhisa , Iuchi Tohru
Published: February 2005

Photoluminescence spectra of CdTe homoepitaxial layers on (100)- and (111)-oriented substrates grown by metalorganic chemical vapor deposition were measured at 4.2 K. Sharp and intense emission peaks at 1.47 and 1.36 eV have been observed in the films grown on (111) substrates. These sharp peaks seem to be structural defect-related emissions and are similar to the Y and Z bands observed in ZnSe.
Microwave Power Dissipation and the Behavior of Flux Lines in the Tl-Ba-Ca-Cu-O System
Authors: Hayashi Yoshikazu , Fukui Minoru , Fujita Tetsuo , Shibayama Hideo , Iwahashi Katsutoshi , Adachi Kengo
Published: February 2005

Measurements of nonresonant microwave absorption nearTcat low magnetic field have been made in a high-Tcsuperconductor of the Tl-Ba-Ca-Cu-O system. Structures appearing in the derivative curve can be decomposed into three components. The first one is due to the Meissner effect. The second and the third ones are related to the entry and the expulsion of flux lines. The relationship between the microwave dissipation and magnetic flux lines in Josephson-coupled superconductors is discussed.
Characterization of Electron Superconducting and Related Nd2-xMxCuO4+y (M=Ce and Th) Compounds
Authors: Huang T. C. , Moran E. , Nazzal A. I. , Torrance J. B. , Wang P. W.
Published: February 2005

Ce- and Th-doped Nd2CuO4+y
superconducting and related compounds were systematically synthesized and characterized. An X-ray diffraction analysis of the variation of lattice dimensions of the Nd2-x
M
x
CuO4+y
compounds revealed that Ce had an average ionic radius of 0.998 Å and an effective valence of +3.84, significantly different from those of the formal Ce3+ and Ce4+ ions. An iodometric titration analysis detected excess oxygen above the nominal value of 4 in both the Ce- and Th-doped materials. The analysis also showed that the average [Cu-O]p charge reversed from positive to negative as x increased, and reached a negative maximum x=0.15 where superconductivity appeared. Using effective valences of +3.84 for Ce and +4 for Th ions, the values of p were found to be -0.067 and -0.048 for the 21 K Nd1.85Ce0.15CuO4.030 and the 15 K Nd1.85Th0.15CuO4.048 electron superconductors, respectively.
Formation of Bi-Pb-Sr-Ca-Cu Oxide Superconducting Layer from Alkoxide Solutions
Authors: Matsumura Kiichiro , Nobumasa Hitoshi , Shimizu Kazuharu , Arima Takahisa , Kitano Yukishige , Tanaka Masataka , Sushida Kazuyoshi
Published: February 2005

The high-T
c phase Bi-Pb-Sr-Ca-Cu oxide superconducting layer was formed from a solution consisting mainly of reaction products of alkoxides with carbon dioxide. Electric resistivity of the layer decreased drastically at 110 K, and became zero at 100 K.
Structure and Superconductivity of Sputtered Bi-Sr-Ca-Cu-O Films from Various Targets
Authors: Sugiyama Jun , Takeuchi Masaharu , Kawamoto Jun-ichi , Igarashi Isemi
Published: February 2005

Bi-Sr-Ca-Cu-O films were prepared by use of the single-target sputtering method: deposited on [100] MgO substrates and then annealed at 860°C. Targets of three types were used: 1) mixed powder of, 2) calcined powder of, 3) a sintered disk of Bi2O3, SrCO3, CaCO3 and CuO. Films made from the type 1) target almost peeled off from the substrate during the annealing, and small residual films consisted of c-axis-oriented phases of Bi2Sr2Ca1Cu2O
x
(2212), Bi2Sr2Ca0Cu1O
x
(2201) and a slight amount of Bi2Sr2Ca2Cu3O
x
(2223). The films from the type 2) and 3) targets did not peel off and consisted of randomly oriented 2212 and 2201 phases.
Effect of Additional Cu Element on Structure and Crystallization Behavior of Amorphous Fe-Nb-Si-B Alloys
Authors: Kataoka Noriyuki , Inoue Akihisa , Masumoto Tsuyoshi , Yoshizawa Yoshihito , Yamauchi Kiyotaka
Published: February 2005

The addition of Cu to an amorphous Fe74.5Nb3Si13.5B9 alloy was found to significantly change the crystallization process, resulting in the formation of a bcc solid solution containing a large amount of the solute elements with fine grains. It was further observed that the inhomogeneity of the amorphous structure increases upon the addition of Cu. The inhomogeneous amorphous structure was presumed to enhance the instability of the amorphous phase and the formation tendency of the bcc solid solution with soft magnetic properties.
Simple Analytical Model for Continuous-Wave-Laser Melting Allowing for Reflectivity Change at the Solid/Liquid Boundary
Authors: Widdershoven F. P.
Published: February 2005

A simple analytical model for continuous-wave-laser melting of bulk materials is presented. The model allows for the reflectivity change at the solid/liquid boundary on the surface. Approximate values for the melt width and depth are obtained without laborious numerical calculation.
Optical Investigation on the Growth Process of GaAs during Migration-Enhanced Epitaxy
Authors: Kobayashi Naoki , Horikoshi Yoshiji
Published: February 2005

The growth process of GaAs is investigated using optical reflection during migration-enhanced epitaxy which is based on an alternate deposition of Ga atoms and As4 molecules onto the growing surface. A linearly polarized laser light is irradiated at a 20° angle with respect to the (001)-oriented GaAs substrate surface. A 325-nm He-Cd laser light with polarization E vector perpendicular to the substrate surface is more efficiently reflected from Ga-stabilized surfaces than from As-stabilized surfaces. Thus, strong and persistent oscillation in reflection intensity is observed during the alternate deposition of Ga and As4. When the polarization E vector of the incident light is parallel to the growing surface, no oscillation is observed. These results imply that the observed optical reflection oscillation is related to the optical absorptions caused by an electronic transition in the As-stabilized surface which couples efficiently with light whose polarization vector is normal to the surface.
Mass Reduction Mechanism in High Tc Superconductivity –Estimate of Tc–
Authors: Ishizaka Satoshi , Izuyama Takeo
Published: February 2005

A two-dimensional electron lattice with alternating spin alignment is considered. When a certain number of holes or excess electrons are injected into this lattice, they will fall into the bound state with the lowet energy, leading to novel superconductivity. The bound state is formed by a pair of holes (or excess electrons) through the mass reduction mechanism. The transition temperature for superconductivity is given by the gap equation, which is solved exactly.
Reaction Mechanism of High-Tc Phase (Tc=110 K) Formation in the Bi-Sr-Ca-Cu-O Superconductive System
Authors: Tsuchiya Jun , Endo Hozumi , Kijima Naoto , Sumiyama Akihiko , Mizuno Masaaki , Oguri Yasuo
Published: February 2005

The reaction mechanism to produce the high-T
c phase was investigated using X-ray powder diffractometry and thermogravimetry and differential thermal analysis (TG-DTA). The high-T
c phase was produced through the low-T
c phase (Bi2Sr3-x
Ca
x
Cu2O
y
, 1<x<2) which was formed as an intermediate reaction product and also as a precursor of the high-T
c phase. In order to produce the high-T
c phase, it is necessary that the melting point of the low-T
c phase be lower than that of the high-T
c phase. Increase of Ca content in the low-T
c phase or decrease of ambient partial oxygen pressure during calcination are quite efficient to decrease the melting point of the low-T
c phase, and hence to enhance the formation of the high-T
c phase.
Superconducting Glass-Ceramic Fine Rods in Bi1Ca1Sr1Cu2Al0.5Ox Prepared under a Temperature Gradient –Tc and the Texture of Specimen–
Authors: Abe Yoshihiro , Arakawa Hisashi , Hosoe Masahiro , Hikichi Yasuo , Iwase Jiro , Hosono Hideo , Kubo Yukio
Published: February 2005

Fine glass rods (dia. 1∼2 mm) in Bi1Ca1Sr1Cu2Al0.5O
x
prepared by pumping up the melt at 1150°C into SiO2 glass tubes were reheated to 845°C according to a given procedure under a temperature gradient (≈30°C/mm) or under no temperature gradient. The incorporated Al enhanced the glassification. In the former specimen crystals grew well to become much larger, and impurity Al was excluded from the superconducting phases on crystallization under a temperature gradient to form the aluminous fibers; the T
c(zero) is ≈80 K and a shoulder appears around 110 K.
Formation of a High-Electrical-Resistance Region in InP by Ga Ion Implantation
Authors: Asahi Hajime , Sumida Hitoshi , Yu Soon Jae , Emura Shuichi , Gonda Shun-ichi , Komuro Masanori
Published: February 2005

A high-electrical-resistance region as high as 1×104 Ω·cm can be formed in Si-doped InP (n=1×1018 cm-3) layers by 8×1014 cm-2 Ga focused ion beam (FIB) implantation and 500–600°C annealing. The clear photoresponse is also observed in the Ga-FIB-implanted diode structures after annealing. A drastic carrier concentration decrease and the existence of residual defects are confirmed by Raman scattering measurement.
Measuring the Temperature of a Quartz Substrate during and after the Pulsed Laser-Induced Crystallization of a-Si:H
Authors: Sameshima Toshiyuki , Hara Masaki , Usui Setsuo
Published: February 2005

Transient thermometry measurements were used to study the heat diffusion in the near-surface region of a quartz substrate when hydrogenated amorphous silicon deposited on the substrate was melted and crystallized by irradiation with a pulsed XeCl excimer laser. The use of a thin platinum layer as a temperature sensing layer made it possible to measure the rapid heat diffusion from the silicon film on the top to the underlying substrate. The substrate was heated to no more than 170°C at 800 nm below the silicon film during and after the crystallization process.
Growth of Lattice-Matched ZnSe-ZnS Superlattices onto GaAs Substrates by Metalorganic Molecular Beam Epitaxy
Authors: Oniyama Hideyuki , Yamaga Shigeki , Yoshikawa Akihiko
Published: February 2005

This paper describes the results of the first attempt to reduce misfit dislocations in epilayers of a wide-band-gap II-VI semiconductor on GaAs substrates by utilizing the ZnSe-ZnS strained-layer superlattice (SLS) structure. From a theoretical calculation, SLSs consisting of a 200 Å-ZnSe and a 10 Å-ZnS layer in one period can be grown as lattice-matched SLSs to GaAs. It has been found from the photoluminescence measurements and electron-beam-induced current (EBIC) image observations that the generation of misfit dislocations can be markedly reduced, as expected.
Bubble-Free Wafer Bonding of GaAs and InP on Silicon in a Microcleanroom
Authors: Lehmann V. , Mitani K. , Stengl R. , Mii T. , Gösele U.
Published: February 2005

A technology is presented that will allow the fabrication of thin III-V compound semiconductor layers of low dislocation density on silicon substrates. GaAs and InP wafers were successfully bonded to bare and oxidized silicon substrates in an experimental setup that produces a microcleanroom for bubble-free bonding in any environment. The bonding strength was found to be comparable to that of Si on oxidized Si and sufficient to subsequent grinding and polishing of the bonded wafers.
A New Reverse Base Current (RBC) of the Bipolar Transistor Induced by Impact Ionization
Authors: Sakui Koji , Hasegawa Takehiro , Fuse Tsuneaki , Seshita Toshiki , Aritome Seiichi , Watanabe Shigeyoshi , Ohuchi Kazunori , Masuoka Fujio
Published: February 2005

We report the observation of base current characteristics of bipolar transistors at a certain collector voltage. The reverse base current (RBC) effect is a newly found phenomenon. The mechanism of the RBC effect can be explained by the impact ionization between the base and the collector. We can successfully analyze the RBC effect. The agreement between simulation and measurement is shown to be very good.
Synthesis and Characterization of High-Tc Superconducting Oxides by the Modified Citrate Gel Process
Authors: Liu R. S. , Wang W. N. , Chang C. T. , Wu P. T.
Published: February 2005

High-T
c superconducting Y-Ba-Cu-O, Bi-Ca-Sr-Cu-O, and Tl-Ca-Ba-Cu-O materials were synthesized using a modified citrate precursor process. Ethylenediamine was used to neutralize the metal citrate solution and facilitate the complex formation. Highly homogeneous and viscous gel without any precipitation was obtained. In the Tl-Ca-Ba-Cu-O system, the Ca-Ba-Cu-O precursor was first prepared by the sol-gel method, then mixed with thallium oxide for final sintering. The complex formation was monitored by UV/VIS spectrophotometry. The thermal decomposition of gels and the formation of superconducting phases had been studied using IR, DTA, TGA, and XRD. This process is highly reproducible and leads to powders with excellent homogeneity and small particle size for easy sinterability.
Properties of a Fluorine-Doped Y-Ba-Cu-Oxide Superconductor Prepared by Hot-Pressing
Authors: Kanai Tsuneyuki , Kamo Tomoichi , Matsuda Shin-pei
Published: February 2005

Fluorine doped Y-Ba-Cu-oxide samples prepared by hot-pressing showed superconductivity without a subsequent heat treatment in oxygen, in contrast to the semiconducting behavior of undoped samples. CuF2 powder was used as the fluorine source. Powders with the nominal composition YBa2Cu3O
y
F0.2 were hot-pressed in oxygen atmosphere at 900–950°C; a density of 5.72–5.83 g/cm3 was obtained. The Meissner effect was observed at 93 K and 75 K in the samples hot-pressed at 900°C and 950°C, respectively. The differing superconductivity between the undoped and F-doped samples may be due to changes in the average copper valence in the Y-Ba-Cu-O system.
Structural Study on Nd1.85Ce0.15CuO4-δ Epitaxial Thin Film Grown by Activated Reactive Evaporation Method
Authors: Kamigaki Kousei , Terauchi Hikaru , Terashima Takahito , Iijima Kenji , Hirata Kazuto , Yamamoto Kazunuki , Hayashi Katsuhiko , Bando Yoshichika
Published: February 2005

New electron-superconductor Nd1.85Ce0.15CuO4-δ epitaxial thin film was successfully grown in situ by means of the activated reactive evaporation method. Temperature dependences of the lattice properties were investigated by means of X-ray diffraction in the temperature range of 10 K–300 K. Debye temperature was estimated to be 430 K using an anharmonic approximation. Evidence of structural change such as a tetragonal-orthorhombic phase tansition was not found, implying that the average structure is tetragonal at the superconducting state.
Spatiotemporal Variation of Light Emission from SF6 Parallel-Plate Discharge at Frequencies of 100 and 500 kHz
Authors: Suganomata Shinji , Ishikawa Itsuo , Ohmoto Shinichiro , Akitsu Tetsuya , Saito Yukinori
Published: February 2005

At a frequency of 500 kHz, the light emission from the discharge in SF6 gas at 0.2 Torr has been observed to be more intensive in front of an instantaneous anode than that from its negative glow. This result suggests that the plasma in the gap of two electrodes becomes an electron source for sustaining the discharge by the detachment of electrons from negative ions, and also that a relatively high electric field exists in front of the electrodes on both sides of the bulk plasma.
Tunneling Acoustic Microscope
Authors: Takata Keiji , Yugami Jiro , Hasegawa Tsuyoshi , Hosaka Sumio , Hosoki Shigeyuki , Komoda Tsutomu
Published: February 2005

A tunneling acoustic microscope is a new type of microscope which is based on both a scanning tunneling microscope and a technique for detecting acoustic waves. It enables simultaneous detection of force interactions between tip and sample and tunneling current. Using this new microscope, defects on silicon surface induced by thermal oxidation have been observed by detecting changes in surface conductivity with high spatial resolutions.
Reduction of Internal Stress by Compositional Gradient Layer Inserted between TiSi2 and Si
Authors: Hata Tomonobu , Tsuchitani Masanobu , Kamiya Kenji , Horita Susumu
Published: February 2005

This paper is concerned with the results of an experiment on reducing the internal stress due to heat treatment of a TiSi2/Si structure. In order to reduce the stress, we inserted a compositional gradient layer between two layers. Plasma controlled sputtering is newly proposed as a means of depositing compositional gradient layer. A 0.2-µm-thick linearly graded transition layer can reduce the internal stress to zero after annealing.
In-Depth Profiling of Suboxide Compositions in the SiO2/Si Interface by Angle-Resolved X-Ray Photoelectron Spectroscopy
Authors: Takakura Masaru , Sunada Takeshi , Miyazaki Seiichi , Hirose Masataka
Published: February 2005

A clean silicon surface was oxidized in a UHV chamber and in-depth profiling of suboxide compositions was carried out by using angle-resolved X-ray photoelectron spectroscopy. The existence of Si-H bonds near the oxide surface is implied because the background hydrogen in the UHV chamber reacts with the oxide surface. This hydrogenated Si bond looks like Si3+ in the Si2p spectrum. It is also shown that the SiO2/Si interface is atomically abrupt.
Photoluminescence Spectra of Silver-Doped ZnSe Grown by MBE
Authors: Miyajima Takao , Akimoto Katsuhiro , Mori Yoshifumi
Published: February 2005

Photoluminescence spectra of silver-doped ZnSe grown by molecular beam epitaxy were studied at 4.2 K. The silver-related peaks were observed at 2.726 eV with phonon replicas and are thought to be due to the radiative recombination of donor-to-silver-acceptor (D-A) emission. The shallow acceptor level of silver in ZnSe is found, and its level is estimated to be about 71 meV from the peak energy of donor-acceptor emission, which would be consistent with the activation energy of thermal quenching of the D-A emission.
Magneto-Optical Kerr Rotation Spectra and Perpendicular Anisotropy in Compositionally Modulated Multilayer Films of Co/Pt and Fe/Pt
Authors: Sugimoto Toshio , Katayama Toshikazu , Suzuki Yoshishige , Nishihara Yoshikazu
Published: February 2005

Magneto-optical Kerr rotation (θK) spectra and magnetic properties such as saturation magnetization (M
s) and perpendicular magnetic anisotropy of Co/Pt and Fe/Pt compositionally modulated multilayer films (CMF's) are investigated. An enhancement of θK is observed at the wavelengths of about 290 and 250 nm in Co/Pt and Fe/Pt CMF's, respectively. It is found that Fe/Pt CMF's turn into perpendicularly magnetized films in the same manner as Co/Pt CMF's when the Fe layer becomes thinner than about 5 Å.
Photo-Assisted Metalorganic Chemical Vapor Deposition of Zinc Oxide Thin Films
Authors: Maruyama Toshiro , Nakai Akinobu
Published: February 2005

Zinc oxide thin films were obtained from dimethylzinc and carbon dioxide or oxygen by the metalorganic chemical vapor deposition method. A low-pressure mercury lamp was used to assist the deposition of films. At a substrate temperature above 200°C, c-axis-oriented polycrystalline thin films were obtained. The deposition rate of the thermally grown films strongly depended on the configuration of the reactor, and effects of photo-irradiation on the deposition rate also changed according to the configuration of the reactor. In a horizontal reactor, the deposition rate actually decreased upon irradiation.
Heteroepitaxial Growth of ZnSxTe1-xon GaAs(100) by RF Sputtering
Authors: Tokumitsu Yoji , Kitayama Haruyuki , Kawabuchi Akira , Imura Takeshi , Osaka Yukio
Published: February 2005

Ternary alloys ZnSxTe1-x(0<x<1) are deposited epitaxially at a substrate temperature of 320°C by rf sputtering on the clean surface of a GaAs(100) substrate from which the surface native oxides have been etched off in advance by H2plasma treatment. The alloy film atx=0.62 shows the best crystalline quality in terms of RHEED patterns with little lattice mismatch with GaAs.
Ac Permeability Measurement for Inter- and Intragrain Critical Current Densities in Oxide Superconductors
Authors: Matsushita Teruo , Ni Baorong
Published: February 2005

A simple measuring method to discriminate between inter- and intragrain current densities in oxide superconductors under given magnetic fields and temperatures is proposed. This is a measurement of the imaginary part of the ac permeability or susceptibility as a function of the ac field amplitude. In this method, the analysis used to derive the penetration depth of the ac field in Campbell's method or the waveform analysis method is not necessary. This method is useful when the value of the penetration field into the grains and that into the bulk specimen are remarkably different.