bluuebunny/crossref_metadata_2025 huggingface dataset:
The Nature of Nitrogen-Oxygen Complexes in Silicon
Authors: Suezawa Masashi , Sumino Koji , Harada Hirofumi , Abe Takao
Published: February 2005

The nature of nitrogen-oxygen complexes acting as shallow donors in silicon was investigated by measuring the optical adsorptions due to the electronic transitions associated with donor electrons. The complexes were eliminated by heat treatment at temperatures higher than 1100°C. The generation processes of nitrogen-oxygen complexes of several kinds were traced by means of both isochronal and isothermal annealings. An analysis of the result led to a picture in which the complexes of the dominant type consist (each) of one oxygen atom and two or three pairs of nitrogen atoms.
Observation of Balmer-Alpha Line Profile of Hydrogen Atoms in Plasmas by Rapid-Frequency-Scan Laser Spectroscopy
Authors: Honda Chikahisa , Maeda Mitsuo , Uchino Kiichiro , Muraoka Katsunori , Akazaki Masanori
Published: February 2005

The possibility of an instantaneous determination of the Balmer alpha (Hα) line profile of hydrogen atoms in large plasma devices by rapid-frequency-scan (RAFS) laser spectroscopy is discussed. A detailed analysis of the SN ratio shows that, although the SN ratio in Hα line profile measurements by RAFS is smaller than those in neutral hydrogen density measurements, a remarkable improvement can be obtained by the choice of the optimum saturation parameter and the long-pulse operation. Based on the experiment of the Hα profile measurement in a hydrogen DC glow discharge plasma by RAFS, the profile distortion in saturated excitation is evaluated. The SN ratio in the profile measurement by RAFS for Heliotron E plasma is estimated from the data on the neutral density measurement.
Atom Arrangement in III-V Quaternary Alloy Semiconductors of (ABC)D Type
Authors: Ichimura Masaya , Sasaki Akio
Published: February 2005

The nonrandomness in atom arrangement has been estimated for III-V quaternary alloys of (ABC)D type through a thermodynamical analysis. As in ternary alloys, the strain energy is considered to be the mixing enthalpy. Calculations were carried out for (InGaAl)As and Ga(SbAsP), and the results are represented in terms of short-range order parameters of second-nearest pairs. The number of pairs increases compared with a random arrangement if composed of larger and smaller atoms than the average; however, the number of pairs of larger or smaller atoms decreases. When the lattice constant of a constituent binary compound coincides with that of an alloy, there appears in the alloy a preference for compound clustering. The results are compared with those for ternary alloys.
Decoupling of N-Soliton Solutions for Volterra and Volterra-Like Circuit Equations
Authors: Narita Kazuaki
Published: February 2005

We decouple the N-soliton solution for the Volterra and Volterra-like circuit equation to the linear superposition of N single soliton solutions. For this purpose, we combine Hirota and Satsuma's result and Yoneyama's result and find expressions for decoupled single solitons. We also find explicit expressions for the decoupled 2-soliton solutions for the Volterra-like circuit equation and examine their behavior.
The Effects of Iodine-Doping on the Hetero-Epitaxial Growth of ZnS on GaP Substrates
Authors: Imai Tetsuji , Fuke Shunro , \testscWatanabe Masahiko , Araki Hitosi , Kuwahara Kazuhiro
Published: February 2005

Single-crystalline ZnS layers have been grown on GaP substrates using an open-tube hydrogen transport system. By the addition of iodine to the reactant agents, the growth rate of ZnS on GaP(111)A decreased and that on GaP(111)B increased. These changes of the growth rates caused by the iodine-doping process were characterized as the opposite behavior compared with those for the indium-doping case. For the growth on the GaP(100) plane, the deposition region has largely shifted to lower temperatures, and higher growth rates, such as 5 µm/h, were obtained at considerably lower temperatures, such as 580°C. From an x-ray diffraction analysis, it was found that a significant improvement in the crystallinity of the grown layers on (100) substrates was caused by the doping of iodine. An improvement in the surface morphology for these layers was also clearly observed.
An Improved Method to Determine the Capture Cross-Section of Majority Carriers from the Pulse-Filling Measurement
Authors: Tomokage Hajime , Morita Shunya , Miyamoto Tokuo
Published: February 2005

A method is proposed to determine the capture cross-section of majority carriers from a change in the capacitance due to trap filling without any influence of slow capture in the depletion edge region. The difference in the capacitance under two bias conditions is measured by microcomputer-based isothermal capacitance transient spectroscopy. The capture cross-section of an electron on Au-acceptor level in Si is obtained to verify this method.
X-Ray Diffraction Characterization of Cadmium Stearate Langmuir-Blodgett Films II
Authors: Mizushima Koichi , Egusa Shun , Azuma Makoto
Published: February 2005

Non-Bragg reflection, which is observed prominently at low angles for Cd stearate Langmuir-Blodgett films, has been analyzed by a method which is a simple extension of the ordinary kinematical diffraction theory, and the applicability of the ordinary theory to the Bragg reflection from very thin LB films was also examined.
Evidence for the crystallization of the films with time and the correlation between the reflection intensity and the kind of substrate are also reported.
Finally, an anomalous enhancement of the reflection intensity observed for particular films deposited on glass or on SiO2 formed thermally on Si is discussed.
Spin-Dependent Luminescence Enhanced by Interface Stress between III–V Alloy Layers on Excitation of Circularly Polarized Light
Authors: Horinaka Hiromichi , Nakanishi Hidenori , Saijyo Takashi , Inada Hiroshi , Sonomura Hajimu , Miyauchi Takeshi
Published: February 2005

The relation between the luminescence polarization for circularly polarized light and the band structure of zincblende semiconductor under two-dimensional stress is theoretically discussed. Two type of samples with an unstrained InP layer and a strained InP layer due to the lattice mismatch are prepared. The luminescence from the InP layer excited by circularly polarized light is analyzed using a Babinet-Soleil compensator, (or phase-modulator) and polarizer. The large luminescence polarization of circularly polarized light is observed in the strained sample. At temperatures below 60 K, the luminescence polarization exceeds 25% which is the maximum value predicted in the unstrained crystal. The experimental results show that the luminescence polarization is increased by the internal strain due to the lattice mismatch.
Preparation of Cobalt-Modified γ-Fe2O3 Thin Films and Their Surface Structures
Authors: Nakayama Kazuhiko , Namikawa Tatsuru , Yamazaki Yohtaro
Published: February 2005

Cobalt modification was made in a wet process for the γ-Fe2O3 thin films which were derived from iron thin films prepared by a vacuum evaporation method. The surface structures were closely investigated by X-ray diffraction, electron microscopic observations of surface replica films, reflection electron diffraction, and ESCA, and were discussed with the magnetic properties. In the modification reaction at 55degC by a simultaneous addition of iron and cobalt ions, δ-(Fe0.67Co0.33)OOH particles which were attached to the spinel-modified layer were detected. The diffusion of the particles into the film and the resulting formation of a spinel phase were found to play important roles in the improvement of the magnetic properties.
Heteroepitaxial Growth of GaN1-xPx(x\lesssim0.06) on Sapphire Substrates
Authors: Igarashi Osamu
Published: February 2005

Gallium nitride phosphide (GaN1-x
P
x
) was epitaxially deposited on (0001) sapphire substrates by the vapor phase reaction of the Ga–Br2–NH3–PH3–N2 system. It was found that the composition x and the growth rate of the GaN1-x
P
x
single crystal strongly depend on the substrate temperature and the flow rate of PH3 introduced into a reaction tube. The composition x increased with decreasing substrate temperature. The maximum composition x obtained was 0.064 at a substrate temperature of 1000degC. The growth rate increased with increasing flow rate of PH3 introduced into the reaction tube. At a substrate temperature of 1030degC, the growth rate of GaN1-x
P
x
(x≈0.05) was 22 times larger than that of GaN. The diffraction lines observed on back-reflection divergent beam patterns of the GaN1-x
P
x
single crystal were broad and did not show the separation due to Kα1
and Kα2
radiation.
Quick Measurement of Nonlinear Conduction with a Single Pulsed Field
Authors: Okazaki Taizo
Published: February 2005

A method of quickly measuring the nonlinear conduction of a semiconductor is developed where a single triangular pulsed field is used. The warm electron coefficient larger than 4 ×10-7 cm2/V2 can be measured when it is well defined up to a sufficiently high field, for instance ∼20 V/cm. Field dependence of the conductivity of pure InSb is measured at 50 K and 63 K, where the nonlinear signal is small and the dependence is complicated.
UV Radiation of a Pulsed Discharge Using Needle-to-Plane Electrodes
Authors: Ko Kwang Cheol , Nakagawa Satoru , Hoshina Yoshikazu , Fukuta Masahiro , Ishii Shozo
Published: February 2005

UV radiation characteristics of a pulsed discharge have been studied in atmospheric pressure. Experiments were carried out by changing the distance between the electrodes, the charging voltage of the capacitor, the resistance of the external circuit, and other features. It is shown that the optimum charging voltage and the gap distance are above 7 kV and above 5 mm, respectively.
CT-Based Bio-Solid-State Battery
Authors: Jain K. M. , Abraham Susamma , Hundet Anuj
Published: February 2005

The ability of vitamin A acetate to form charge-transfer (CT)-complexes in the solid state with electron acceptors has been exploited for the direct conversion if chemical energy into electrical energy. The electrochemical cell devised for this purpose has the configuration zinc/CT complex/Pt or graphite. An open-circuit voltage of 1.08 V and short-circuit current densities of up to 5 mA/cm2 were found at room temperature. The current-voltage and discharge characteristics gave a maximum power density of 4.0 W/kg and a useful energy density of 17 W·h/kg, respectively. The battery was found to be useful in operating various low-power-consuming electronic circuits.
Resistivity Correction Factor for the Four-Probe Method: Experiment I
Authors: Yamashita Masato , Yamaguchi Shoji , Enjoji Hideo
Published: February 2005

Experimental verification of the theoretically derived resistivity correction factor (RCF) is presented. Resistivity and sheet resistance measurements by the four-probe method are made on three samples: isotropic graphite, ITO film and Au film. It is indicated that the RCF can correct the apparent variations of experimental data to yield reasonable resistivities and sheet resistances.
Production of Highly Charged Metal Ions and Soft X-Ray Emission in a Plasma Focus
Authors: Hirano Katsumi , Yamamoto Toshikazu , Takada Satoshi , Sone Hisao , Shimada Katsuji
Published: February 2005

An electron beam generated in a plasma focus device was used to produce highly charged metal ions. Soft X-ray emission from the ions was investigated with a flat crystal spectrograph, a time-resolved soft X-ray pinhole camera and a framing interferometer. As a target for the soft X-ray emission, molybdenum was adopted. Molybdenum ions of MoXXXI-MoXXXIV have been successfully generated. Also, it has been demonstrated that the plasma focus is a simple and inexpensive device for generating soft X-ray spectra of highly charged metal ions.
Critical Behaviors of the NMR Line Width in Vinylidene Fluoride and Trifluoroethylene Copolymers near Tc
Authors: Ishii Fumiaki , Tsutsumi Akihiro , Odajima Akira
Published: February 2005

NMR line widths in VDF/TrFE copolymers with VDF 65 and 52 mol.% were measured as a function of the alignment angle γ between the drawn axis and the magnetic field over a temperature range from 20 to 130degC and the results were compared with those for VDF 72 mol.% copolymer.
In the cooling process, a slight increase was observed on the line width for each copolymer near the Curie temperature T
c, which depended on the angle γ. This finding was explained by applying the effective Ising model to the configuration fluctuation of the trans segments. The anomalous part of the line width, ΔH
fluc with the form of T
2(T-T
0)-1/2 was derived. Using the experimental values of ΔH
fluc for each copolymer, the effective nearest-neighbor distance, d, between fluctuating trans segments, and the correlation length, ξ, were calculated. Both the values of d and ξ became larger in the order of 72, 52 and 65 mol.%. The magnitude of ξ for each copolymer was very close to the average distance, r (=5.9 A), between the fluctuating order units. The contribution of ξ to the polarization fluctuation was discussed by comparing the results which had been obtained from the spin-lattice relaxation time measurement.
Hot Electron Drift Velocity in AlGaAs/GaAs Heterojunctions
Authors: Lasserre Jean , Tanimoto Hiroyoshi , Taniguchi Kenji , Hamaguchi Chihiro
Published: February 2005

We investigate electron transport in two different types of selectively doped single AlGaAs/GaAs heterojunctions for electric fields up to 2 kV/cm and compare our experimental results with those of a Monte Carlo simulation. In both cases, although good agreement is found at low fields, a discrepancy arises as the electric field reaches higher values. Experimental drift velocities saturate gradually whereas the calculations predict a negative differential mobility beyond 3 kV/cm. Finally, we calculate the electric field dependence of the drift velocity for various electronic densities in one of our structures and show that below 2 kV/cm, the drift velocity increases with increasing electronic sheet density.
Vector Magnetometer and Its Application to Measurement of Magnetization Vector in Some Ferromagnets
Authors: Inaba Nobuyuki , Miyajima Hideki , Chikazumi Soshin
Published: February 2005

A vector magnetometer, which enables the determination of the three-dimensional orientation of a magnetic moment as well as its magnitude, has been constructed. As this magnetometer is able to measure simultaneously three components of the magnetization vector by using three pairs of pick-up coil systems, it is useful to investigate not only the technical magnetization process but also the magnetocrystalline anisotropy in a single crystal specimen. Polar maps of the magnetization vector in Nd–Fe–B permanent magnets and ferromagnetic Fe–Sn alloys were determined as functions of magnetic field and temperature. The polar maps in the Nd2Fe14B magnet are explained in terms of the distribution of domain magnetizations, considering spin reorientation. In contrast, the magnetization process of Fe–Sn alloy is interpreted by a simple concept of rotation magnetization.
Dependence of Energy Gap on x in CuAlxGa1-xS2 Mixed Crystal System
Authors: Tsuboi Nozomu , Kobayashi Satoshi , Kaneko Futao , Maruyama Takeo
Published: February 2005

The transmission and reflectance spectra for various x in CuAl
x
Ga1-x
S2 single crystals have been measured with polarized light. The photon energies of excitons associated with the uppermost valence bands are determined by analyzing the exciton absorption spectra and the reflectance anomaly spectra at room temperature and at about 80 K. The exciton energies have an approximately quadratic dependence of x. The valence band splitting is predominantly due to the crystal field splitting. The splitting energy varies almost linearly with x.
Cathodoluminescence of Ga2(S1-xTex)3 Crystals and Films
Authors: Iwamura Yasuo , Hokakubo Katuhiko , Moriyama Makoto
Published: February 2005

In a solid solution Ga2(S1-x
Te
x
)3 prepared by an improved method, a uniform and intense cathodoluminescence is observed over the entire polycrystalline sample. The optimum composition for an intense luminescence is found to be x∼0.25. The composition dependence of an optical energy gap and the luminescence spectrum of the sample are obtained. Thin films are grown on Si substrate and their light-emitting characteristics are also measured. Composition dependence of emission intensity may be attributed to the fact that the sample is a mixture of a crystal with a tetragonal structure and an α-Ga2S3 crystal in the composition range 0<x<0.20.
Synthesis of Superconductive Oxides by Vacuum Calcination Method
Authors: Uno Naoki , Enomoto Noritsugu , Tanaka Yasuzo , Takami Hiroshi
Published: February 2005

The vacuum calcination method (VCM) was developed to synthesize Ln-Ba-Cu-O group superconductive oxides represented by YBa2Cu3O7-x
through solid phase reaction. When Y2O3, BaCO3 and CuO are used as raw materials in the form of powder in this method, the carbon content of the resultant calcinated product will be 1/10 that of the normal methods or lower.
VCM powder is a mixture of Y2BaCuO5 and BaCu
x
O
y
, an unknown phase, and has extremely high activity because of oxygen content that is lower than the stoichiometric composition of YBa2Cu3O7-x
.
For this reason, it absorbs oxygen during sintering under an oxidizing atmosphere causing transition to the perovskite phase of YBa2Cu3O7-x
, thus indicating excellent sinterability and high J
c and magnetization.
A 105 K Superconducting Phase in the Bi-Sr-Ca-Cu-O System
Authors: Ono Akira , Kosuda Kosuke , Sueno Shigeho , Ishizawa Yoshio
Published: February 2005

We report a 105 K superconducting phase crystallized at 883°C as a major phase with large grain sizes. X-ray powder diffraction showed a very broad 002 reflection of 17.8 Å, although chemical compositions were relatively homogeneous. The 105 K phase has a Cu-rich and Bi-poor composition compared with the 80 K superconducting phase.
Photoquenching and Recovery Effects of EL2 Absorption in GaAs
Authors: Tajima Michio , Saito Hiroki , Iino Takayuki , Ishida Koichi
Published: February 2005

Optical absorption spectroscopy on the major midgap donor (EL2) in GaAs shows that the metastable state of the EL2 level (EL2*) can be optically recovered to the normal state (EL20) at 11 K. On the basis of the transient properties of the photoquenching and recovery effects, we suggest that these effects occur as a result of a dynamic balance between the EL20→EL2* and EL2*→EL20 transitions.
Effect of Pressure on Superconducting Transition Temperature of Bi-Ca-Sr-Cu-O
Authors: Kumagai Kazuo , Kurisu Makio
Published: February 2005

We have determined the pressure dependence of the superconducting transition temperatures, T
c's of multiphase Bi1Ca1Sr1Cu2O
x
under hydrostatic pressure up to about 30 kbar. The observed pressure dependence of T
c, that both the upper and lower T
c's increase linearly with pressure, is compared to those of other high-T
c oxide compounds (La, M)2CuO4-y
(M=Sr and Ba) and YBa2Cu3O7-y
.
High-Tc Phase Promoted and Stabilized in the Bi, Pb-Sr-Ca-Cu-O System
Authors: Takano Mikio , Takada Jun , Oda Kiichi , Kitaguchi Hitoshi , Miura Yoshinari , Ikeda Yasunori , Tomii Yoichi , Mazaki Hiromasa
Published: February 2005

Partial substitution of Pb for Bi in the Bi-Sr-Ca-Cu-O system has been found to sharply increase the volume fraction of the high-T
c phase when both the starting material (coprecipitated oxalate being used in the present study) and the heating process are appropriate. The sharp powder X-ray diffraction pattern obtained from well-grown particles, 5∼10 µm wide and 0.5 µm thick typically, was assigned to an orthorhombic cell with a=0.537 nm, b=2.682 nm, and c=3.726 nm. The electrical resistance dropped to zero at 107 K within the experimental limit of 10-6 Ω. A large diamagnetic response in the ac susceptibility due to the Meissner effect was seen below 120 K. The dominance of the high-T
c phase over the low-T
c phase was roughly estimated at 9/1 in volume.
Long Period Structures in the Bi-Sr-Cu-O System
Authors: Fujiki Hideo , Sano Masaru , Tomimoto Koukichi , Sawa Hiroshi , Akimitsu Jun , Kitamura Norihisa
Published: February 2005

The structure of the superconducting Bi-Sr-Cu oxide system was studied by means of electron diffraction. Three kinds of long period structures were found in this system. The relation between these long period structures and the nonstoichiometry in this system is discussed.
YBa2Cu3Oy Annealed under High-Pressure Oxidizing Atmosphere
Authors: Sato Makoto , Konaka Tsuneo , Sankawa Izumi
Published: February 2005

Heat treatment under high-pressure oxidizing atmosphere (oxygen partial pressure of 400 atm) is found to lower the T
c of the superconductor YBa2Cu3O
y
. The powder X-ray diffraction pattern and the oxygen content measurement suggest that the excess oxygen occupies the oxygen defect site between the Ba-Ba layers.
The Effect of Annealing in High-Pressure Oxygen on YBa2(Cu1-xMx)3Oy (M=Co, Ni, Zn)
Authors: Shimakawa Yuichi , Kubo Yoshimi , Utsumi Kazuaki , Takeda Yasuo , Takano Mikio
Published: February 2005

The effect of annealing in high-pressure oxygen on YBa2(Cu1-x
M
x
)3O
y
(M=Co, Ni, Zn) was studied. The T
c, structure and oxygen content of Ni- and Zn-doped samples were little changed by annealing in high-pressure oxygen, while Co-doped samples were found to have transition temperatures that increased with increasing oxygen content. This difference is attributed to the extra oxygen atoms introduced into the microdomain boundaries by annealing in high-pressure oxygen. The extra oxygen atoms can “smooth” the microdomain boundaries and increase the [Cu-O]+ hole concentration, thus improving the superconductivity.
Effects of Sulfur Addition on the Superconductivity of Y-Ba-Cu-O Compound
Authors: Matsubara Ichiro , Tanigawa Hideo , Ogura Toru , Kose Saburo
Published: February 2005

Sulfur added Y-Ba-Cu-O compounds with a nominal composition YBa2Cu3O
x
S
y
were prepared by two methods; a) using CuS or Cu2S instead of CuO, b) annealing the YBa2Cu3O
x
in H2S atmosphere. By the method a), sulfur atoms were not incorporated into the crystal lattice of the 1:2:3 phase and made it multiphasic. Although T
c was lowered with increasing sulfur content, J
c for y=0.03 was about twice as high as that for y=0.00. In the case of the method b), sulfur atoms could be incorporated into the crystal lattice of 1:2:3 phase when the compound was annealed at temperatures up to 200°C. The sulfur-incorporated compounds showed semiconductive behavior.
Superconductivity in YBa2Cu3O7-δ Thick Films by the Atmospheric Plasma Powder Spraying
Authors: Sankawa Izumi , Konaka Tsuneo , Matsuura Taketoshi , Ishihara Koshi
Published: February 2005

Thick films composed of Y-Ba-Cu-O (e.g. 70 µm thick) were prepared on Ni alloy substrates at various temperatures by the atmospheric plasma powder spraying method. By increasing the substrate temperature during the spraying, the amount of unknown structure in the film sprayed was lowered and the structure of the film sprayed on 600°C substrate was tetragonal in phase. After the postannealing at 600°C, this film revealed superconducting temperatures for onset and zero resistance of 92 K and 86 K, respectively.
Preparation of Thin Films by Coevaporation and Phase Identification in Bi-Sr-Ca-Cu-O System
Authors: Yoshitake Tsutomu , Satoh Tetsuro , Kubo Yoshimi , Igarashi Hitoshi
Published: February 2005

Thin films of a Bi-Sr-Ca-Cu-O system were prepared on MgO substrate by coevaporation of Bi2O3, Sr0.5Ca0.5 alloy and Cu. The films were characterized by X-ray diffraction, dc resistivity and EPMA. By post-deposition annealing the film at 850°C for 12 hours, the film showed a superconducting transition with onset T
c of 91 K and zero resistance T
c of 82 K. The tetragonal phase Bi2Sr2CaCu2O
x
with a c-axis of 30.7 Å was responsible for this superconducting transition. The film annealed at 890°C for 5 hours showed a superconduting transition with onset T
c of 115 K and zero resistance T
c of 103 K. The tetragonal phase Bi2Sr2Ca2Cu3O
x
with a c-axis of ∼37 Å was responsible for this superconducting transition.
Preparation of YBaCuO Thin Film dc SQUID
Authors: Katoh Yujiro , Asahi Masayoshi , Asano Hidefumi , Michikami Osamu
Published: February 2005

This paper discusses the preparation of thin oxide film dc SQUIDs (Superconducting Quantum Interference Devices). A c-axis oriented, 600 nm-thick polycrystalline as-grown superconducting Y-Ba-Cu-O thin film, which was deposited on a (100) SrTiO3 single crystal, was used. An Ar ion milling technique has successfully been applied for patterning the 5∼20 µm wide microbridge without causing damage to the film. The modulation of the critical current has been clearly observed from 4.2 K to slightly higher than 40 K.
Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facets
Authors: Ukita Hiroo , Mise Keisuke , Katagiri Yoshitada
Published: February 2005

A laser diode facet reflectivity measuring method which uses the threshold current ratio of an antireflection coated to an uncoated laser is proposed. The method's measuring characteristics are determined and compared with those of conventional methods. The proposed method is simpler, easier and more accurate than conventional methods, such as the two-facet power ratio method and the spectrum modulation index method even for low facet reflectivities.
First Observation of Quantum Hall Effect in InP-MISFET
Authors: Okamura Masamichi , Yamaguchi Eiichi , Hirota Yukihiro
Published: February 2005

The first observation of the quantum Hall effect in an InP-MISFET is reported. Although electron mobility in this system is lower than that in other systems, Hall plateaus in Hall resistance are clearly observed.
GaAs Inversion-Base Bipolar Transistor (GaAs IBT) with Graded Emitter Barrier
Authors: Matsumoto Kazuhiko , Hayashi Yutaka , Nagata Toshiyuki , Yoshimoto Tomomi
Published: February 2005

In the GaAs inversion-baser bipolar transistor, the graded layer was introduced to the emitter barrier. It was proved that the graded layer decreased the effective barrier height of the emitter barrier and enhanced the electron flow from the emitter to the collector. These effects of the graded layer improved the current gain of the GaAs IBT by two orders of magnitude.
40 nm Width Structure of GaAs Fabricated by Fine Focused Ion Beam Lithography and Chlorine Reactive Ion Etching
Authors: Shiokawa Takao , Kim Pil Hyon , Hamagaki Manabu , Hara Tamio , Aoyagi Yoshinobu , Toyoda Koichi , Namba Susumu
Published: February 2005

A 40 nm width structure of GaAs is fabricated by Be++ fine focused ion beam lithography and chlorine reactive ion etching using electron beam excited plasma (EBEP). The nanometer structure of the fabricated GaAs has a high aspect ratio of about 17 and a vertical side wall. It is found that the fabrication process has a high potential for nanometer microfabrication.
Crystal Growth Faults in Superconductor Tl-Ba-Ca-Cu-O Oxide Crystals
Authors: Iijima Sumio , Ichihashi Toshinari , Kubo Yoshimi
Published: February 2005

Superconductor oxides, Tl2Ba2CaCu2O8+x
(2212) and Tl2Ba2Ca2Cu3O10+x
(2223), in the Tl-Ba-Ca-Cu-O system are intimately intergrown in various types of fine scale stacking faults. Removal of these planar faults is a key point in growing large single crystals of the 2223 phase. Among various planar faults, planar boundary structures between the 2212 and 2223 phases were studied by an electron microscope. Slab widths of the 2212 phase terminated on a (110) plane in the 2223 phase tend to have the width of a 5:4 lattice fringe line ratio. A structure for the boundary and its stability is discussed in terms of the solid state reaction.
Effect of Anode Surface on Growth of Silicon Oxide Needles Induced by Positive Corona Discharge
Authors: Nashimoto Keiichi
Published: February 2005

Using several kinds of wire anode materials for positive corona discharge, growths of silicon oxide on the anodes were studied by discharging in air containing dimethylpolysiloxane vapor or in atmospheric air at atmospheric pressure. Though many silicon oxide needles grew on a carbon-coated tungsten wire anode, almost only silicon oxide film grew on a platinum wire anode. However, when the surface of the platinum wire anode was contaminated with NaOH, a large amount of needles grew on the anode. In this study, the importance of the surface of the wire anode for the growth of silicon oxide needles was found.
Annealing Behavior of Twin Domains in YBa2Cu3Ox Crystals
Authors: Sawada Tsutomu , Takei Humihiko , Takekawa Shunji , Kitamura Kenji , Kimura Shigeyuki , Iyi Nobuo
Published: February 2005

The behavior of YBa2Cu3O
x
crystals upon annealing was investigated by a polarizing microscope. Gradual transformation between the orthorhombic and tetragonal phases was observed in situ on heating and on cooling in oxygen atmosphere. An obvious change was recognized between twin domain structures before and after annealing. It is indicated that there is a possibility of reducing the number of twin domains in the crystal.
Orthorhombic-II Phase in Ba2YCu3O7-X Crystals
Authors: Ichihashi Toshinari , Iijima Sumio , Kubo Yoshimi , Tabuchi Junji
Published: February 2005

The structure in a wide oxygen-deficiency range of Ba2YCu3O7-X
crystal (0.15<X<0.78) prepared by a quenching method was examined by electron optical methods. The crystal structure modification for the ortho-II phase (T
c∼60 K, X∼0.5), whose shorter a-axis is doubled, is considered to be an ordered oxygen-vacancy arrangement caused by removing oxygen atoms from alternating oxygen atoms and their vacancy arrays along the [010] direction on Cu(1)-plane. The mechanism for the ortho-I →the ortho-II →the “incipient” tetragonal phase transformation is discussed in terms of oxygen-deficiency.
Structure and Bonding at the CaF2/GaAs(111) Interface
Authors: Yamada Yasuko , Oshima Masaharu , Waho Takao , Kawamura Tomoaki , Maeyama Satoshi , Miyahara Tuneaki
Published: February 2005

Surface sensitive core level spectroscopy with synchrotron radiation (SRPES) is performed to determine bonding properties at the CaF2/GaAs(111) interface. The layer-by-layer growth of CaF2 was found. CaF2 interfacial states were clearly distinguished from CaF2 bulk states using chemical shifts of Ca3p and F2s core levels. Although the stoichiometry of CaF2 in the first layer differs from that of CaF2 bulk, the interface is abrupt, implying the possibility of MIS devices with good quality. A structural model with an abrupt interface and layer-grown CaF2 film is proposed based on these SRPES results.
Theoretical Study of Mode Transition between 2d-Nucleation and Step Flow in MBE Growth of GaAs
Authors: Nishinaga Tatau , Cho Kyoung-Ik
Published: February 2005

The disappearance of RHEED intensity oscillation by increasing growth temperature in GaAs MBE on a stepped surface has been studied theoretically based on the 2d-nucleation and surface diffusion theories. By comparing the present and the published RHEED results, we get the surface diffusion length (λs) and the diffusion coefficient (D
s) of Ga atoms on the (100) GaAs surface respectively as

λs[cm]=4.0 ×10-8 exp
(0.3/k
T)

and
D
s[cm2/s]=1.6 ×10-2 exp
(-1.1/k
T).
Synthesis of the 107 K Superconducting Phase in the Bi-Sr-Ca-Cu-O System
Authors: Ono Akira
Published: February 2005

Synthetic conditions of the 107 K superconducting phase in the Bi-Sr-Ca-Cu-O system were investigated to obtain a pure ceramic material of the 107 K phase. From the starting materials identical to compositions of the 107 K phase, the 80 K phase was prepared as a predominant metastable phase. For the formation of a large fraction of the 107 K phase, kinetic conditions such as the presence of a small amount of liquid phase, special bulk compositions, special temperatures and long heating times become the important factors, although the 107 K phases showed large compositional variations and were stable at least at 870–900°C in air.
Annealing Effect on Resistivity of BiSrCaCu2Oy
Authors: Terada Hiroshi , Ido Toshiyuki , Muto Saburo
Published: February 2005

The annealing effect on the resistivity and the critical temperature of BiSrCaCu2O
y
where the low temperature phase is predominant was examined. The resistivity becomes higher, as increasing the annealing temperature in N2 atmosphere and the sample annealed above 700°C did not show zero resistance from 20 K to 300 K. However, the resistivity and the critical temperature recover nearly the same value as the as-grown sample after annealing in O2 atmosphere.
Superconductivity of Bi2Sr2Ca2Cu3PbxOy (x=0.2, 0.4, 0.6)
Authors: Mizuno Masaaki , Endo Hozumi , Tsuchiya Jun , Kijima Naoto , Sumiyama Akihiko , Oguri Yasuo
Published: February 2005

The addition of Pb to the superconducting Bi-Sr-Ca-Cu-O system is found to increase the volume fraction of the high-T
c phase (T
c>100 K) determined by the ac susceptibility and the X-ray powder diffraction pattern. It also lowers the optimum firing temperature to produce the high-T
c phase. The peaks attributed to the high-T
c phase in the X-ray diffraction pattern become sharper, which indicates that the addition of Pb promotes crystallization. It is found by differential thermal analyses that Pb also acts as a flux.
High Resolution Electron Microscopy of Intergrowth and Modulated Structure in 110 K High-Tc Superconductor Bi2(Sr, Ca)4Cu3Oy
Authors: Matsui Yoshio , Takekawa Shunji , Nozaki Hiroshi , Umezono Akihiro , Takayama-Muromachi Eiji , Horiuchi Shigeo
Published: February 2005

The high-T
c superconductor Bi2(Sr, Ca)4Cu3O
y
with T
c=110 K is examined by high resolution electron microscopy. Most of the perovskite-related layers are composed of three CuO2 and four (Sr, Ca)O layers, separating two Bi2O2 layers by 1.8 nm. Intergrowths of perovskite-related layers containing two, four and five CuO2 layers are observed, where the Bi2O2 layers are separated by 1.5, 2.1 and 2.4 nm, respectively. The structural modulation, similar to that reported in the 80 K low-T
c superconductor Bi2(Sr, Ca)3Cu2O
y
(Y. Matsui et al.: Jpn. J. Appl. Phys. 27 (1988) L372), is also observed.
Characteristics in the Growth of the YBa2Cu3Ox and YBaSrCu3Ox Crystalline Films
Authors: Yoshida Masashi
Published: February 2005

The change of the structure of the sputter-deposited films of YBa2Cu3O
x
and YBaSrCu3O
x
by thermal annealing was investigated using X-ray diffraction spectrometry. The YBa2Cu3O
x
films crystallized in the distorted perovskite structure when annealed above 940°C while the YBaSrCu3O
x
above 980°C. The merging of (200), (020) and (006) lines was observed in the YBa2Cu3O
x
annealed at 800°C or in the YBaSrCu3O
x
annealed between 800°C and 940°C. It was also found that by the annealing of the films of YBaSrCu3O
x
, the YBa2Cu3O
x
crystals grew preferentially below 900°C while the YBaSrCu3O
x
crystals grew above 900°C.
High-Power CW Operation in V-Channeled Substrate Inner-Stripe Lasers with “Torch”-Shaped Waveguide
Authors: Kawanishi Hidenori , Morimoto Taiji , Yamaguchi Masahiro , Kaneiwa Shinji , Miyauchi Nobuyuki , Yoshida Toshihiko , Hayashi Hiroshi , Yano Seiki , Hijikata Toshiki
Published: February 2005

High-power AlGaAs lasers with a waveguide pattern like a torch have been grown by a two-step liquid-phase epitaxy process. The waveguide pattern consists of a 6 µm-wide region about 220 µm long and a 10 µ-wide region about 20 µm long connected by a tapered region about 10 µm long. A stable fundamental transverse mode has been obtained of up to more than 200 mW output power in a 4%–95% coated device in the wavelength range of 830 nm. The lasers have extremely high reliability, and stable continuous operation for over 4000 hours has been confirmed at 50°C, 50 mW with no obvious degradation.
A Modified 1.5 µm GaInAsP/InP Bundle-Integrated-Guide Distributed-Bragg-Reflector (BIG-DBR) Laser with an Inner Island Substrate
Authors: Wang W. , Pang M. T. , Komori K. , Lee K. S. , Arai S. , Suematsu Y.
Published: February 2005

A modified GaInAsP/InP BIG-DBR laser for restricting leakage current via the passive DBR region is proposed and realized by using an inner-island substrate with a quaternary blocking layer as well as employing an island-type active mesa process.
As a result, superior lasing properties were attained such as a low CW threshold current of 22 mA, a high side-mode suppression ratio of 38 dB, and a narrow spectral linewidth of 4.7 MHz. A wide temperature range of 87 degrees for a fixed single-mode operation was obtained.
Superlattice Structure Observation for (AlAs)1/2(GaAs)1/2 Grown on (001) Vicinal GaAs Substrates
Authors: Fukui Takashi , Saito Hisao , Tokura Yasuhiro
Published: February 2005

(AlAs)1/2(GaAs)1/2 fractional-layer superlattices with a new periodicity, perpendicular to the growth direction, are grown by metalorganic chemical vapor deposition (MOCVD) on (001) GaAs substrates, slightly misoriented towards [1̄10]. The periodic structure in the lateral [1̄10] direction is observed by high-resolution transmission electron microscopy (TEM). The superlattice image is clearly observed, and the superlattice periods are almost uniform everywhere. The results show that monolayer steps are ordered and equidistant from each other. These monolayer step ordering mechanisms are explained using the kinetic equation for terrace width.
Amorphous Alloys with Nitride Particles Produced by a Nitrogen Plasma-Alloy Reaction
Authors: Inoue Akihisa , Oguchi Masahiro , Kim Byung Geol , Misaki Hitoshi , Masumoto Tsuyoshi
Published: February 2005

By taking advantage of the high reactivity of nitrogen plasma with molten metal in arc melting, an amorphous foil with ZrN or NbN particles was produced for easy glass-forming Fe-Cr-Mo-P-C alloys containing Zr or Nb. The application of melt spinning to the duplex-phase foils was found to bring about the formation of an amorphous alloy ribbon having dispersed ZrN or NbN particles. The new processing technique and the duplex amorphous alloys are expected to attract increasing attention because of the possibility of multifunctional characteristics which are not obtained for an amorphous single phase.
Optimization in Spot Sizes of Focused MeV Ion Beam by Precise Adjustment of Lens-Current Excitations
Authors: Kinomura Atsushi , Takai Mikio , Matsuo Takahiro , Kiuchi Masato , Fujii Kanenaga , Satou Mamoru , Namba Susumu
Published: February 2005

Effects of lens-current excitations and object slit width on the beam spot sizes have been investigated to minimize the spot size in a microbeam line with 1.5 MeV helium ions, focused by piezo-driven object slits and a magnetic quadrupole doublet. Deviation of a lens-current excitation by 0.5% gave rise to an 80% increase in the beam spot size. A minimum spot size of 0.9 µm ×1.2 µm was obtained by an improvement in the adjustment of the lens-current excitations.
Laser Multiphoton Ionization Spectrum of AlCH3 Radicals Formed by UV Excimer Laser Photolysis of Gaseous TMA at 248 nm and 193 nm
Authors: Zhang Y. , Stuke M.
Published: February 2005

The UV excimer laser photolysis of TMA, trimethylaluminum ((CH3)3Al)2, a dimer at room temperature, yields efficient generation of AlCH3 molecules, which have been detected and identified by tunable laser mass spectroscopy for the first time. Aluminum dimers are not detected. The AlCH3 molecules are not precursor of the Al atoms, which are also produced in high abundance. The efficient generation of a carbon containing aluminum compound 193 nm from TMA may be one important source of carbon incorporation into aluminum films formed by UV excimer laser photolysis of TMA as organometallic precursor.
Absorption Current and Impurity Ions in Nematic Liquid Crystal Cells
Authors: Mada Hitoshi , Yoshino Shigeru
Published: February 2005

An absorption current flowing in liquid crystal cells has been measured in order to detect the behavior of impurity ions. The measured current is proportional to t
-1 for the region in the initial few seconds. These results agree with the theoretical solution in which the diffusion term in approximation is ignored. The saturated charge density of a surface double layer is about 8.7×10-5 C/m2, which is in the same order as that estimated in a previous paper, 2×1011 ions/cm2. The electric double layer model is also demonstrated.
Microscopic Mechanism for Annealing of Photocreated Dangling Bonds in a-Si:H
Authors: Morigaki Kazuo
Published: February 2005

A microscopic mechanism for annealing of photocreated dangling bonds in a-Si:H is presented taking into account hydrogen plays an important role in annealing of dangling bonds. This model can account for the experimental fact that photocreated dangling bonds as well as thermally created dangling bonds are annealed at relatively low temperatures such as 100–150°C in a-Si:H.
Photochemical Vapor Deposition of Aluminum Thin Films Using Dimethylaluminum Hydride
Authors: Hanabusa Mitsugu , Hayakawa Kikuo , Oikawa Akira , Maeda Katsunori
Published: February 2005

Using dimethylaluminum hydride as a source gas, aluminum thin films with low-electrical resistivity were deposited via photochemical reactions induced by a deuterium lamp. The best resistivity was 6.2 µΩ·cm, which was as low as 2.3 times the value of bulk aluminum. Deposition rates increased with substrate temperature. At 200°C the rate was 20 nm/min. A disk-like thickness profile, as well as the vapor pressure dependence of deposition rates, indicated that surface reactions dominated.
Si-SiO2 Interface Structures–Chemical Shifts in Si 2p Photoelectron Spectra–
Authors: Yamagishi Hiroaki , Koike Noboru , Imai Keitaro , Yamabe Kikuo , Hattori Takeo
Published: February 2005

From XPS depth profiling of silicon oxide films formed on (100), (110) and (111) surfaces prepared by various oxidation processes, the effect of crystallographic orientation on the chemical shift was found, and the effects of oxidation temperature, oxidation atmosphere and annealing on the chemical shifts were found to be small. These results imply that chemical shifts are weakly affected by the change in the Si-O-Si bond angle near the Si-SiO2 interface.
Interfacial Superstructure of AlN/n-GaAs(001) System Fabricated by Metalorganic Chemical Vapor Deposition
Authors: Akimoto Koichi , Hirosawa Ichiro , Mizuki Jun'ichiro , Fujieda Shinji , Matsumoto Yoshishige , Matsui Junji
Published: February 2005

The superstructures at the insulator/semiconductor interface were observed for the first time by grazing incidence X-ray diffraction. The insulating AlN was deposited on the n-GaAs(001) substrate by the metalorganic chemical vapor deposition utilizing TMA and N2H4 as source gases in a H2 ambient gas at a pressure of 0.1 atm. At the beginning of AlN deposition at 220°C, either TMA or N2H4 was initially introduced before both of them were supplied together, resulting in two different diffraction patterns. For the TMA case, the diffraction pattern showed a 1×4 superstructure and for the N2H4 case, on the other hand, the diffraction pattern showed a 1×6 superstructure. It is suggested that superstructures should appear even at a pressure of 0.1 atm of a H2 gas.
Heteroepitaxial Growth of Yttria-Stabilized Zirconia (YSZ) on Silicon
Authors: Fukumoto Hirofumi , Imura Takeshi , Osaka Yukio
Published: February 2005

Yttria-stabilized zirconia (YSZ) films have been grown on Si(100) substrates heated at 800°C by vacuum evaporation. X-ray diffraction and reflection high-energy electron diffraction observations reveal the heteroepitaxial growth of cubic YSZ (200) films on Si(100) substrates. The reflection high-energy electron diffraction of the films show that the <011 > and <010 > directions in the plane of cubic YSZ nearly coincide with the <010 > and <011 > directions of the Si substrate, respectively. Accordingly, (200)-oriented cubic YSZ could be exactly (<1%) lattice-matched to (100)-oriented Si substrates.
Critical Current Density and Microstructure of Superconducting YBa2Cu3O7-δ Films Prepared by a Tape Casting Method
Authors: Ishii Mamoru , Matsuda Motohide , Takata Masasuke , Yamashita Tsutomu , Tsukamoto Keizou
Published: February 2005

The superconducting YBa2Cu3O7-δ films were prepared by a tape casting method. The critical current density was strongly dependent on the sintering temperature and the film sintered at 900°C showed a maximum value of 400 A/cm2 (77 K and 0 T). The second phase was observed to exist on the grain boundary of the films sintered at temperatures above 910°C.
Precise EXAFS Analysis for High-Tc YBa2Cu3Ox
Authors: Kajiyama Hiroshi , Usami Katsuhisa , Suzuki Yoshio , Sekiyama Hideo , Takagi Kazumasa , Hayakawa Kazunobu , Hirai Yasuharu , Hirano Tatsumi , Waki Izumi
Published: February 2005

EXAFS oscillation caused by oxygen atoms around the Cu atoms in high-T
c orthorhombic YBa2Cu3O
x
(T
c=90 K) is studied. Although the experimental EXAFS profile has been explained by the conventional analysis in which only one kind of Cu-O pairs is assumed to be present, this assumption is found to lead to a misunderstanding of the Cu-O structure. The Cu-O structure should be analyzed by taking into account the contributions from the individual Cu-O pairs based on the reported structure by the Rietveld analysis of the neutron diffraction data. Comparison of theoretical EXAFS with the experiment does not suggest trivalent Cu ions in orthorhombic YBa2Cu3O
x
.
Synthesis of Long and Short Period Bi-Ca-Sr-Cu Oxides
Authors: Kajitani Tsuyoshi , Hirabayashi Makoto , Kikuchi Masae , Kusaba Keiji , Syono Yasuhiko , Kobayashi Norio , Iwasaki Hideo , Muto Yoshio
Published: February 2005

Partial phase diagram of the BiO1.5, (Ca, Sr)O and CuO pseudoternary system at 1133 K has been determined by the X-ray diffraction method. The chemical composition range where the c∼30 Å (T
c∼80 K) phase becomes stable has been found in the vicinities of the metal ratio Bi/(Ca, Sr)/Cu between 2/3/2 and 2/2/3. A unique metal ratio 5/8/8 suitable for the c∼36 Å (T
c∼110 K) phase is found. A pellet, in which 85 volume % of it showed the diamagnetism at 4 K and the volume ratio of the high-T
c phase vs low-T
c phase was about 6/1, was synthesized by the firing at about 1148 K and following annealing at 1143, 1123 and 773 K.
Properties of Pb-Doped Bi-Sr-Ca-Cu-O Superconductors
Authors: Yanagisawa Eiji , Dietderich Daniel R. , Kumakura Hiroaki , Togano Kazumasa , Maeda Hiroshi , Takahashi Kazuhiko
Published: February 2005

The effect of Pb-doping of the new high-T
c Bi-Sr-Ca-Cu-O superconductors prepared by conventional solid-state reactions has been studied. A zero resistance transition temperature of 110 K has been achieved for a sample heat treatment of 845°C for 300 h. The sample contains the high-T
c phase (Bi2Sr2Ca2Cu3O
x
) as the major phase plus the low-T
c phase (Bi2Sr2Ca1Cu2O
x
) and other compounds as minor phases. The critical current density at 100 K in a zero magnetic field is 32 A/cm2, which is much larger than that of the Pb-free sample.
Epitaxial Growth of High-Tc Bi-Ca-Sr-Cu-O Superconducting Layer by LPE Process
Authors: Liu R. S. , Huang Y. T. , Wu P. T. , Chu J. J.
Published: February 2005

A Bi-Ca-Sr-Cu-O epitaxy layer has been successfully synthesized by the liquid-phase epitaxial (LPE) process on the MgO(001) substrate. X-ray diffraction patterns and SEM surface morphology analysis indicated a highly preferred orientation. This film showed superconductivity with onset and zero resistivity temperature of 110 K and 81 K, respectively.
Y1Ba2Cu3O7-δ Film Formation by an OM-CVD Method
Authors: Abe Hitoshi , Tsuruoka Taiji , Nakamori Tomohiro
Published: February 2005

In this letter, we report further studies on Y-Ba-Cu-O film formation by OM-CVD (Organometallic Chemical Vapor Deposition). Without postannealing, Y-Ba-Cu-O films grown on MgO(100) single-crystal substrates at a substrate temperature of 780°C showed an onset temperature of 85 K and zero resistance at 65 K. X-ray diffraction (XRD) patterns showed well-ordered crystallinity for films grown at substrate temperatures higher than 700°C. XRD results indicated that Y-Ba-Cu-O films with (110) orientation were grown on SrTiO3(110) single-crystal substrates.