bluuebunny/crossref_metadata_2025 huggingface dataset:
UHF Bulk-Acoustic-Wave Filters Utilizing Thin ZnO/SiO2-Diaphragms on Silicon
Authors: Nakamura Kiyoshi , Ohashi Yoshio , Shimizu Hiroshi
Published: November 2005

This paper reports on a temperature-stable bulk-acoustic-wave (BAW) filter consisting of a thin ZnO/SiO2 composite diaphragm structure on a silicon wafer. To make a theoretical treatment of the BAW filter possible, the constants for the distributed-parameter equivalent circuit extended to the composite structure are derived from analysis of the dispersion curves for waves propagating along the ZnO/SiO2 diaphragm. Some actual filters are designed and analysed using the equivalent circuit. The measured characteristics of a 578-MHz BAW filter of the two-coupled-resonator type fabricated on silicon are reported and discussed. The results demonstrate that the measured characteristics resemble the theoretical ones but that the insertion loss is as high as 12 dB.
Polarization Behavior in Vinylidene Fluoride-Trifluoroethylene Copolymer Thin Films
Authors: Kimura Kuniko , Ohigashi Hiroji
Published: November 2005

The polarization behavior in films of vinylidene fluoride trifluoroethylene copolymer (P(VDF-TrFE), VDF/TrFE molar content ratio of 75/25) of thickness less than 1 µm is reported. Ferroelectricity is maintained even in 0.06 µm-thick film, whose saturated polarization is as large as that for thick films (100 mC/m2). However, the crystallites are much smaller than in thick film, and the coercive field in the thin film is higher (125 MV/m) for the 0.06 µm-thick film) than that of the thick one (40 MV/m). The switching time does not follow the exponential law, but is inversely proportional to the applied field. To analyze these data, we introduce a model in which the thin film contains many defects in its crystalline phase, and the local field in the film is modulated by the defects. The observed switching behavior is consistent with the model.
Analysis of Impact Ionization Phenomena in InP by Monte Carlo Simulation
Authors: Osaka Fukunobu , Mikawa Takashi , Wada Osamu
Published: November 2005

Impact ionizations by electrons and holes in InP have been analyzed by a Monte Carlo simulation. The carrier energy distribution functions, average carrier energy and variations of carrier energy after each scattering event have been calculated for a wide range of applied electric field strengths, and the behavior of the carrier in the high-field region has been investigated. The calculated results have clarified how the impact ionizations by electrons and holes occur in InP. The factors dominating the impact ionization rates of electrons and holes in InP have been identified, and the conditions for enhancing the electron or hole ionization rate are discussed.
Proposal of and Numerical Simulation of Hg1-xCdxTe Heterojunction Bipolar Transistors
Authors: Sakamoto Kunihiro , Okabe Yoichi
Published: November 2005

A novel heterojunction bipolar transistor (HBT) made from Hg1-x
Cd
x
Te is proposed. This narrow-gap material permits an HBT very low voltage operation at low temperature, which in turn gives very high speed switching and extremely low power consumption. A numerical 1-dimensional analysis of a typical HBT structure indicates that it can develop a strong nonlinearity at a small voltage and that a cutoff frequency of 200 GHz is attainable. The estimated power consumption of an (HgCd)Te ECL gate is several times smaller and the power-delay product is one order of magnitude smaller than that of an Si or an (AlGa)As ECL gate.
Low-Temperature Silicon Epitaxial Growth by CO2 Laser CVD Using SiH4 Gas
Authors: Meguro Takashi , Ishihara Yukihito , Itoh Tadatsugu , Tashiro Hideo
Published: November 2005

Silicon epitaxial growth at a low substrate temperature by CO2 laser chemical vapor deposition using SiH4 has been investigated. Single-crystalline Si was grown at a deposition rate of 15 A/s at 650°C under an SiH4 pressure of 0.05 Torr and a CO2 laser power of 6 W/cm2 on an Si substrate. The crystalline quality of deposited Si films was examined by reflection high-energy electron diffraction, and it was found that the deposition rate depends on the incident angle and the polarization of the CO2 laser beam. This is the first report on low-temperature Si epitaxial growth by CO2 laser CVD.
Estimation of Low-Energy Ion Bombardment Damage on GaAs(001) Surface by X-Ray Photoelectron Diffraction
Authors: Sekino Yuko , Owari Masanori , Kudo Masahiro , Nihei Yoshimasa
Published: November 2005

The structural damage on a GaAs (001) surface was estimated by means of X-ray photoelectron diffraction (XPED), which was induced by 170-1200 eV ion bombardment at various polar angles of ion-incidence. The thickness of the damage, which was saturated at a sufficiently high ion dosage, was obtained using a `homogeneous two-layer model'. The saturation thickness, which varied from 4 to 36 Å, decreased as the ion acceleration voltage decreased and the polar angle of ion incidence increased. In the state before saturation, a `mosaic two-layer model' was applied, and the results indicated that the initial rate of the damage formation of the ion bombardment depended on the ion acceleration voltage and the angle of ion-incidence. The `displacement yield', i.e., the number of displaced atoms produced by one ion, was obtained.
Effects of Plasma Motions on Transport of High-Voltage Pulse Power through a Slender Self-Magnetically Insulated Transmission Line
Authors: Sato Morihiko , Mizui Jun-ichi , Yonezu Hiroaki , Tazima Teruhiko
Published: November 2005

Direct electric power input to a pellet may prove to be the simplest method of compression in inertial confinement fusion. One of the crucial questions about this method, however, is how much power can be transported to the pellet through a slender self-magnetically insulated transmission line (MITL) without a large loss. Experimental results show that the transport efficiency of pulse power is determined by the gap closure time caused by plasma expansion from the anode and the cathode surface of the slender MITL. This implies that a shorter voltage pulse width (10∼20 ns) is required for a gap length of a few millimeters to attain a high transport efficiency.
Measurement of Particle Movement Using Time Correlation Analysis of Dynamic Image
Authors: Miike Hidetoshi , Shimada Kazuyuki , Ochiai Kouji , Hashimoto Hajime
Published: November 2005

A new dynamic image-processing technique is proposed for the analysis of particle movement. On the basis of the time correlation analysis, three processed images termed “standard deviation image”, “autocorrelation image” and “mutual-correlation image” are constructed for measuring the information about the particle movement. A rectilinear motion and a vortex motion of crowded particles are described as examples of dynamic images. It is demonstrated that the locus, speed and direction of moving particles at a given site can be estimated from the three processed images.
Extended X-Ray-Absorption Fine-Structure Beats: Application to III-V Semiconductors
Authors: Sasaki Toru , Onda Tomohiro , Ito Ryoichi , Ogasawara Nagaatsu
Published: November 2005

The extended X-ray-absorption fine-structure beat method is applied to cases in which two scattering shells are composed of different atomic species. Though a knowledge of phase shift difference is required, the separation of the closely-lying shells can be obtained without any adjustable parameter. The method was tested on GaAs, InAs and In0.53Ga0.47As, and an accuracy of 0.02 Å was obtained.
Appearance of Depolarization Current in ITC Measurements
Authors: Parakash Jai , Nishad A. K. , Rahul Rahul
Published: November 2005

A method is developed to evaluate the magnitude of the relaxation time when impurity-vacancy (IV) dipole is either frozen-in in the crystalline lattice or ceases to be polarized after the application of the electric field. Relaxation time of frozen-in IV dipoles is evaluated in NaCl, KCl, KBr, KI, AgCl, CaF2, SrF2, SrCl2, CdF2 and BaF2 systems. It is found that the evaluated relaxation time is fixed for a particular host lattice and is independent of the dopants.
Lattice Vibrations of Ba(Zn1/3Ta2/3)O3 Crystal with Ordered Perovskite Structure
Authors: Tamura Hiroshi , Sagala Djuniadi A. , Wakino Kikuo
Published: November 2005

Ba(Zn1/3Ta2/3)O3 dielectric ceramics are known to be useful materials for microwave dielectric resonators. The lattice vibrations of Ba(ZnTa)O3, a crystal which has a pseudocubic unit cell with a hexagonal superstructure because Zn and Ta ions are in an ordered configuration, are investigated in this paper. Also, the symmetry properties of Ba(ZnTa)O3 and its ion displacements are examined.
The far-infrared reflection spectra and Raman spectra of the ceramics are also presented and discussed in relation to the dielectric losses.
Alkali Bismuth Niobates, RbBi2Nb5O16 and CsBi2Nb5O16, with a Pyrochlore Structure
Authors: Sugai Tokukō
Published: November 2005

A phase equilibrium study of the ternary system A2O-Bi2O3-Nb2O5 (A=K, Rb or Cs) has been made. An extended range of a solid solution with the pyrochlore-type structure was found in the respective system. The composition of this new phase is described by a representative formula ABi2Nb5O16, which exists mainly along a composition range BiNbO4-ANb3O8. Phase diagrams of BiNbO4-ANb3O8 systems with A=K, Rb and Cs were determined.
Large single crystals of RbBi2Nb5O16 and CsBi2Nb5O16 were grown by the pulling method. They exhibit dielectric anomalies at 120-130 K.
Long Time Range Breakdown Due to Field Distortion in PET Film Subjected to Step Voltage
Authors: Kitani Isamu , Arii Kiyomitsu
Published: November 2005

When a relatively low step voltage was applied to a PET film, the breakdown time lags were normally distributed in the minute range. The mean time lag at a field strength of 4.5 MV/cm, as an example, was 451 seconds at 25°C, 185 seconds at 40°C and 79 seconds at 60°C, respectively. The periodic reversal of the polarity of the applied field increased the mean time lag, although it had an effect on breakdown during the respective first several seconds. These and other experimental results suggest that the breakdown was brought about by a field distortion due to the formation of a space charge in the PET subjected to a step voltage for a long period.
Simultaneous Observation of RHEED Oscillation during GaAs MBE Growth with Modulated Electron Beam
Authors: Sugiura Hideo , Kawashima Minoru , Horikoshi Yoshiji
Published: November 2005

RHEED oscillations are simultaneously observed in different locations on growing GaAs by scanning the growth surface with an incident electron beam. The lateral growth-rate profiles obtained by in-situ measurements using modulated electron-beam scanning agree well with those of layer-thickness measurements made after growth. The time needed to complete the growth of the 1st monolayer distinctly differs from that of the succeeding monolayers, while the growth duration is almost constant for each succeeding monolayer. The time required for the 1st monolayer growth depends on the location on the growth surface, as well as on such growth parameters as the arsenic flux and substrate temperature.
Measurements of Flow Velocity and Temperature Profile in A Propane-Oxygen Combustion MHD Channel
Authors: Aoki Yoshiaki , Kayukawa Naoyuki , Yamazaki Hatsuo
Published: November 2005

In a propane-oxygen combustion MHD channel, experimental measurements were made of the plasma flow velocity by means of a cross-correlation function analysis and of the boundary-layer temperature-profile by a newly-devised light-polarization line-reversal method. The following results were obtained: the velocity decreased gradually, the temperature profile of the boundary layer varied appreciably as the magnitude of the externally applied magnetic field increased, and the temperature increased from Joule heating, making the boundary layer profile steeper.
Free Energies and Equilibrium States of Mono- and Bi-Layer Superstructures of III-V Ternary Alloy Semiconductors
Authors: Ichimura Masaya , Sasaki Akio
Published: November 2005

Equations for the free energies of mono- and bi-layer superstructures of III-V ternary alloy systems were derived as functions of the order parameter ϕ (random atom arrangement when ϕ = 0 and a complete ordered arrangement when ϕ = 1). It was assumed in the analysis that mixing enthalpy was a strain energy caused by mixing. By minimizing the free energy, we obtained the value of ϕ at the equilibrium state. The values are larger than zero for monolayer superstructures on (100) and (110) surfaces below certain temperatures. For monolayer superstructures on a (111) surface, the stable states are at ϕ = 0, i.e., random arrangements at all temperatures. Bilayer superstructures are less stable than monolayer superstructures of the corresponding surface orientation.
Properties of Tetragonal PLZT with Reference to its Diffuse Phase Transition
Authors: Yokosuka Masaru , Marutake Masakazu
Published: November 2005

Measurements were made of the dielectric, elastic, electrostrictive, piezoelectric and linear thermal expansion constants together with an X-ray analysis of the hot-pressed ceramics of PLZT X/55/45, X being varied from 0 to 15. Here, a new model is introduced regarding the structure of the intermediate state between the paraelectric and the ferroelectric states, the so-called “slim-loop ferroelectric state.” It is assumed that this state is composed of polar microdomains embedded within a non-polar paraelectric matrix and whose orientations change with time. On the basis of this model, the temperature dependence of the dielectric constant and the free energy are calculated with appropriate approximations. It is also shown that this model can explain the so-called “glassy polarization” which extends far above the Curie temperature.
Study of Hot-Pressed Ba(Ca1/3Nb2/3)O3-PbZrO3-PbTiO3 Ceramics. I. Electrical and Optical Properties at Room Temperature
Authors: Yokosuka Masaru
Published: November 2005

Dielectric, piezoelectric and optical properties were investigated at room temperature for hot-pressed and ordinarily fired ceramics in a ternary system of Ba(Ca1/3Nb2/3)O3-PbZrO3-PbTiO3. A phase diagram, dielectric constants and electromechanical coupling factors are shown. Optical transmittances higher than 65% at 600 nm were observed for polished thin plates (0.25 mm thick). Also, large electrooptic coefficients (linear (r
c) and quadratic (R)) were measured for specimens with compositions near the morphotropic boundary between tetragonal and rhombohedral phases. The overall characteristics of the present material were found to resemble those of PLZT.
Cathodoluminescence Study of Striation in In-Doped LEC GaAs Crystals
Authors: Ono Haruhiko , Kamejima Taibun , Watanabe Hisao , Matsui Junji
Published: November 2005

Growth striations in In-doped LEC-grown GaAs crystals were investigated by means of cathodoluminescence (CL). Spatial variation signals of the CL intensity across the striations were observed to depend on the detected wavelength. The variation is interpreted to correspond to the periodical variation of the energy band gap, which is related to microscopic inhomogeneity of In concentration across the striations. The concentration varies periodically within 10∼20% of its average value. The striations revealed by photo-etching were in complete agreement with those observed by CL.
A Bloch Line Pair Generator Using the Flank Wall near the Stripe Domain Head for the Bloch Line Memory
Authors: Hidaka Yasuharu
Published: November 2005

A technique for injecting a vertical Bloch line (VBL) pair into a stripe domain head has been developed. This method utilizes horizontal Bloch line punch-through at the flank wall and successive domain chopping. The method is more practical than that of pushing the stripe domain head. In the new method, the domain is only controlled to lie beneath the conductor pattern for a VBL pair injection. Experimentally, a result of VBL pair injection is shown using 5 µm bubble garnet film and a reasonable margin is obtained in the pulsed bias field vs its width.
Slow Neutron Polarization by Longitudinally Polarized Proton Filter
Authors: Ishimoto Shigeru , Isagawa Shigeru , Masuda Yasuhiro , Morimoto Kimio , Nakajima Tetsuo , Masaike Akira , Ishida Masayoshi , Ishikawa Yoshikazu , Kohgi Masahumi , Newsam John M.
Published: November 2005

The neutron beam with the energy between 10-2 eV and 10 eV could be polarized by the longitudinally polarized proton filter. In this experiment, we found that the polarization cross section for the longitudinally polarized filter is approximately the same value as that for the transversely polarized one.
LEC Growth of High Purity InP Crystals by Pre-Encapsulation of Starting Material
Authors: Kubota Eishi , Katsui Akinori
Published: November 2005

InP crystals were grown by the liquid encapsulated Czochralski (LEC) technique, in which the starting materials in a pBN crucible were previously encapsulated with B2O3 using an outer vacuum vessel. The electrical properties throughout the LEC-grown InP crystals were improved by using the pre-encapsulated starting materials. This is due to the reduced incorporation into the crystals of impurities such as S and C, which are evaporated from carbon heater and radiation shield materials.
New High Current Low Energy Ion Source
Authors: Hara Tamio , Hamagaki Manabu , Sanda Atsuo , Aoyagi Yoshinobu , Namba Susumu
Published: November 2005

We have developed a new type of ion source which is excited by a low energy and high current electron beam. The source has an extractable ion current density up to 0.62 A/cm2 and a low acceleration voltage less than 60 V. This ion source will open a new way for low energy ion processing like damageless ion etching, ion beam crystal growth and deposition.
Characterization of Lattice Defect Structures at GaAs/Si Interface by Transmission Electron Microscopy
Authors: Ishida Koichi , Akiyama Masahiro , Nishi Seiji
Published: November 2005

Lattice defect structure at GaAs/Si interface has been studied by transmission electron microscopy. The GaAs layer was grown by the two-step MOCVD growth procedure in which a thin GaAs buffer layer was grown at a low temperature(\lesssim450°C). The large misfit stress is found to be relieved by misfit dislocations at the GaAs/Si interface. These misfit dislocations are introduced during solid phase epitaxial regrowth of the polycrystalline buffer layer. The observed moire fringes for the buffer layer/Si system demonstrate that the lattice of the regrown buffer layer is relaxed to a nearly unstressed state, and thus, GaAs can be grown at higher temperatures (∼750°C) without generation of lattice defects.
An Interpretation of the Telegraph Equation for Animal Movement near Boundary Wall
Authors: Sato Tadashi , Terao Kunio
Published: November 2005

The telegraph equation with an additional drift term has been obtained from a one-dimensional asymmetric random walk model for an animal. If there is a boundary wall, a solution of this equation provides an exponential distribution decreasing from the boundary for the steady-state. The results suggest that the diffusion process governed by the Fokker-Planck equation can explain well the experimental position distributions of a goldfish, which decrease exponentially from the wall of the aquarium, just like the distribution of the atmospheric density on the earth under the gravity.
Silicon-29 Nuclear Magnetic Resonance Study of Amorphous-Microcrystalline Mixed-Phase Hydrogenated Silicon
Authors: Hayashi Shigenobu , Hayamizu Kikuko , Yamasaki Satoshi , Matsuda Akihisa , Tanaka Kazunobu
Published: November 2005

29Si nuclear magnetic resonance spectra have been measured for amorphous-microcrystalline mixed-phase hydrogenated silicon (µc-Si:H) and amorphous hydrogenated silicon (a-Si:H), using cross-polarization and magic-angle sample-spinning techniques. A narrow 29Si signal with a width of 9 ppm can be obtained without the cross polarization technique only in µc-Si:H, which suggests that moving Si atoms are present in µc-Si:H, while not in a-Si:H.
Detection of Neutral Particles Desorbed by Ion Impact
Authors: Enatsu Masao , Ueda Kazuyuki
Published: November 2005

A detection method of neutral molecules ejected during ion impact is described. Ejected neutral CO-molecules were detected by a quadrupole mass spectrometer aided by beam blanking method using a micro-processor, and the desorption of a CO adsorbed Fee(111) single crystal surface was studied.
Effect of Aluminium Composition on the Luminescence of AlAs/AlxGa1-xAs Multiple Quantum Wells
Authors: Miguel Jose Luis de , Fujiwara Kenzo , Briones Fernando , Ploog Klaus
Published: November 2005

The influence of Al composition x on the optical properties of AlAs/Al
x
Ga1-x
As multiple quantum well heteroestructures (MQWH) is studied by photoluminescence (PL) and photoluminescence excitation spectroscopy (PLE) at 2 K. Besides the expected high energy shift of the luminescence lines with increasing Al concentration in the wells, broader PL peaks and larger Stokes shifts between PL and PLE heavy-hole related excitons are observed. A simple model based only on alloy broadening cannot explain these features. We therefore assume that also a progressive deterioration of the interface quality due to an enhanced three dimensional character of the particular growth mode of the ternary Al
x
Ga1-x
As alloy is responsible for the increased linewidth and Stokes shift.
Photon Stimulated Desorption of Positive Ions from LiF
Authors: Yasue Tsuneo , Gotoh Tetsuji , Ichimiya Ayahiko , Kawaguchi Yoichi , Kotani Masahiro , Ohtani Shunsuke , Shigeta Yukichi , Takagi Shoji , Tazawa Yuji , Tominaga Goroh
Published: November 2005

Photon stimulated desorption (PSD) of positive ions from LiF is observed in the photon energy region between 30 and 70 eV. The creation of the Li+(1s→2s) core exciton leads to the rapid rise of both Li+ and F+ desorption yields. It is found that PSD of positive ions from LiF is due to the interatomic Auger transition. The yield spectrum of F+ ions is different from that of Li+ ions above 60 eV. The F+ yield spectrum has a deep valley at around 63 eV, while the Li+ spectrum shows a plateau in the same region. However the difference in the yield spectra of Li+ and F+ ions can not be explained at present.
Observation of Scattering Loss Peaks at Certain Wavelengths in Fluoride Glass Optical Fibers
Authors: Ghosh Gorachand , Kachi Sumio , Nakamura Kazunori , Kimura Masaki
Published: November 2005

Scattering losses of infrared fluoride glass optical fibers have been measured by a cubic detector in the 0.45 to 1.1 µm region and peaks at 0.525, 0.58, 0.74, 0.80, and 0.865 µms have been observed for the first time. These peaks are considered due to the photoluminescence effect by the rare earth impurities within the fiber.
Effect of In Situ Carbon Coating on ICRF-Heated Tokamak Plasmas Relating to Radiation Loss by Iron-Impurities in JIPP T-IIU
Authors: Noda Nobuaki , Ogawa Yuichi , Masai Kuniaki , Ogawa Isamu , Ando Ritoku , Hirokura Satoru , Kako Eiji , Taniguchi Yoshiyuki , Akiyama Ryuichi , Kawasumi Yoshiaki , Kawahata Kazuo , Toi Kazuo , Watari Tetsuo , Tanahashi Shugo , Matsuoka Keisuke , Hamada Yasuji
Published: November 2005

The effect of the C-coating has been demonstrated for tokamak plasmas with high power heating. In situ carbon coating has been made with a glow discharge in a methane/hydrogen mixture gas. Without C-coating, iron contamination has been so severe in megawatts of ICRF heating that the total radiation loss exceeds the rf-heating power, and the electron temperature, after once heating up, then decreases continuously during the latter half of 55 ms rf pulse. With C-coating, the radiation loss is reduced to be one fifth of the rf power and the electron temperature T

e
becomes stationary at the end of the rf pulse. As a result of this change in T

e
, the total stored energy increases more than the one without C-coating.
High Pressure Operation of an Electron Beam Gun
Authors: Fusayama Takao
Published: November 2005

An electron beam gun has been continuously operated at ambient pressure up to 5 Torr in helium and 0.5 Torr in argon using narrow gap electrodes and a plasma cathode. Contrary to a hollow cathode electron gun, this device is such that electron beam energy and current are independently controlled without current loss even in the low energy region. A maximum electron energy up to 2 keV and current density of 0.6 A·cm-2 are obtained by means of graphite perforated plate electrodes.
GaAs/In0.08Ga0.92As Double Heterojunction Bipolar Transistors with a Lattice-Mismatched Base
Authors: Ito Hiroshi , Ishibashi Tadao
Published: November 2005

The critical layer thickness for misfit dislocation generation in a GaAs/InGas/GaAs DH structure is investigated experimentally. Introduction of compositionally graded layers with 300 Å thickness into hetero-interfaces is found to increase the critical layer thickness for misfit dislocation generation about three-fold. An optimum growth temperature of about 510°C is obtained by measuring the photoluminescence intensity of the DH structure. Using these results, a GaAs/In0.08Ga0.92As heterojunction bipolar transistor with a lattice mismatched InGaAs base is fabricated for the first time. The current gain of 20 is achieved at a collector current density of 2×104 A/cm2.
Magnetic Effects in the Synthesis of Tin and Tin Oxide Structures
Authors: Rusanov V. , Bonchev Ts , Mihov M. , Petrov S.
Published: November 2005

Magnetic-spin effects have been observed in the process of oxidation of the new α2-Sn allotropic form. The experimental data is explained within the Merrifield mechanism. It is shown that in sufficiently strong magnetic fields the synthesized samples contain significant quantities of α2-Sn.
Effects of Acid Vapor, Basic Vapor and Heat Treatments on the Properties of Langmuir-Blodgett Films of Divalent Metal Salts of Fatty Acids
Authors: Saito Mitsuyoshi , Sugi Michio , Ikegami Keiichi , Yoneyama Mitsuru , Iizima Sigeru
Published: November 2005

When LB films are exposed to the atmosphere vaporized from acid at room temperature, the X-ray diffraction peaks attributed to the lamellar structure disappear and new peaks appear depending on the metal ion species of the salt, whereas such noticeable change is not observed by basic vapor treatment and heat treatment. Diffraction patterns for LB films of free fatty acids are not influenced by these three treatments.
Effect of High-Frequency Toroidal Magnetic Filed on a Reversed Field Pinch Plasma Configuration
Authors: Tukada Tokuaki , Kitamura Hiroshi , Itagaki Kouichi
Published: November 2005

A small amplitude of high-frequency toroidal magnetic field is superposed to a reversed field pinch plasma with small scale. In spite of the small amplitude, a significant improvement in suppressing an m=1 instability at the beginning of the self-reversal process is observed.
Multiple-Shell Pellet for Plasma Fueling
Authors: Ito Sanae-Inoue , Itoh Kimitaka , Sengoku Seio
Published: November 2005

A pellet with shell structure is proposed to reduce the tritium circulation in magnetic fusion devices. As an example, the tritium core is covered by a deuterium layer in order to deposit tritium ions in the central core region of hot plasma.
Surface Damage of Reactive Ion Beam Etched GaAs
Authors: Nagata Koichi , Nakajima Osaake , Ishibashi Tadao
Published: November 2005

Surface damage induced in GaAs by reactive ion beam etching (RIBE) with BCI3 is investigated. A Schottky diode structure fabricated on the etched surface is employed for characterizing the RIBE damage. To evaluate the degree of the damage with high sensitivity, the specific contact resistance through the tunneling process is measured as well as the Schottky diode parameters. The damage due to RIBE causes very little change in the Schottky diode characteristics. However, it drastically increases the specific contact resistance. This results from the decrease of the effective carrier concentration in the thin (less than 200Å ) surface damage layer.
Modulation Doped n-AlGaAs/GaAs Heterostructures Grown by Flow-rate Modulation Epitaxy
Authors: Makimoto Toshiki , Kobayashi Naoki , Horikoshi Yoshiji
Published: November 2005

Flow-rate Modulation Epitaxy was applied to grow GaAs, AlAs, AlGaAs layers and n-AlGaAs/GaAs modulation doped heterostructures. This method considerably reduced the growth temperature, and high-quality GaAs and AlAs layers were obtained at the growth temperature as low as 550°C. Al
x
Ga1-x
As alloy layers, where x=n/(n+m), were formed by repeating the growth of m-monolayers of GaAs followed by the growth of n-monolayers of AlAs. Thus, the Al
x
Ga1-x
As layers are no longer “random alloys” but have “ordered structures”. It was found that, in Flow-rate Modulation Epitaxy, the Si doping efficiency to Al0.25Ga0.75As is quite high, and is almost constant in the growth temperature range between 500 and 625°C. Using this method, we fabricated modulation doped n-AlGaAs/GaAs heterostructures. At the growth temperature of 550°C, the 2DEG mobility as high as 7×104 cm2/Vs was obtained at 6 K.
Voltage-Dependence of Scanning Tunneling Microscopy on Titanium Surface in Air
Authors: Morita Seizo , Okada Takao , Ishigame Yuri , Sato Chiaki , Mikoshiba Nobuo
Published: November 2005

Using a scanning tunneling microscope (STM), we have investigated surfaces of a commercial titanium plate in air. We found that the tunneling current depends nonlinearly on the voltage. In order to interpret such a nonlinear dependence, we proposed a model that a tunneling process between TiO
x
and W contributes to the tunneling current in addition to that between Ti and W. We found also the tunneling-voltage-dependence of the STM image which was consistent with the proposed tunneling model.
Designing New Materials with Amorphous Semiconductors–Structure and Electrical Properties of Multiply Stacked a-Si/a-SiGex Layers–
Authors: Shirai Hajime , Tanabe Akihito , Hanna Jun-ichi , Oda Shunri , Nakamura Tetsuro , Shimizu Isamu
Published: November 2005

A new kind of material composed of narrow band-gap substances was prepared by multiply stacking a-Si:H(F) and a-SiGe
x
:H(F), which exhibited high photoconductivity, while the dark conductivity was kept low. Photoconductivity was measured both in plane and perpendicular to the layers, suggesting no extra recombination states in the interface. The drift mobilities of electrons and holes were measured at room temperature by the time-of-flight technique, showing 1×10-2 cm2/Vs and 6.0×10-3/Vs, respectively. The fact that high resistivity is maintained in this structure despite lowering of the band gap makes it a promising material as a photoconductor, exhibiting high sensitivity for near-infrared light.
MoO3 Electron Resist and Its Application to Fabrication of Mo Fine Pattern
Authors: Kumada Fusayoshi , Okamoto Masaaki , Baba Mamoru , Ikeda Toshio
Published: November 2005

Amorphous MoO3 films become insoluble in pure water after electron irradiation and can be used as negative-type electron resists. A fine pattern with a resolution of the order of 0.5 µm is easily generated. A fine pattern of the metallic Mo is also fabricated by the reduction treatment of the MoO3. pattern in an H2 atmosphere above 500°C. The minimum electrical resistivity of the reduced Mo is 7.4×10-5 Ω·cm, which is obtained by the reduction treatment at 850°C.
Calculation of Interfacial Energy of the fcc-bce Interface and Its Epitaxial Orientation Relationship
Authors: Gotoh Yoshihiko , Arai Isao
Published: November 2005

The numerical calculation of interfacial energy of the fcc-bcc interface has been carried out using a simple two-dimensional interaction potential energy. The results of the calculation for Ag/Mo and Ag/Fe systems by the new model are in good agreement with the experimental evidence, i.e., the Kurdjumov-Sachs orientation relationship and Nishiyama-Wassermann orientation relationship, respectively. Moreover, a prediction of the preferred orientation of epitaxy for various combinations can be made from the dependence of the interfacial energy on bulk atomic diameter ratio between fcc and bcc.
Nb–Cu–Nb Bridges Fabricated by Direction of Sputtering Deposition and Anodic Oxidization
Authors: Nakano Hiroshi , Aomine Takafumi
Published: November 2005

We fabricated Nb–Cu–Nb bridges by direction of sputtering deposition and anodic oxidization, and conducted experiments on effects of microwave radiation and temperature dependences of critical current on these bridges. Using our simple fabrication procedure, we were able to obtain Josephson junctions with short length easily.
High Resolution Electron Microscopy of Composite Films of Iron and Magnesium Oxide
Authors: Nagao Masaru , Tanaka Nobuo , Mihama Kazuhiro
Published: November 2005

Composite films of iron and magnesium oxide are prepared by a simultaneous deposition technique. An important feature of the films is that iron is grown epitaxially and separately with the size of around 1 nm inside (001) and (11̄0) magnesium oxide films of about 25 nm thickness. The structures of the films are studied by high resolution electronmicroscopy. The heat treatment of the composite films brings about the grain growth and the phase transformation of iron crystallites from α-iron to γ-iron.
Characterization of µc-Si:H Prepared by Photo-Chemical Vapor Deposition
Authors: Suzuki Kazuhiko , Aota Katsumi , Aihara Takaaki , Suzuki Tadashi , Kuroiwa Koichi , Tarui Yasuo
Published: November 2005

Microcrystalline silicon deposited by photo-CVD is characterized to reveal dependence of crystallinity on the film preparation conditions. The volume fraction of microcrystalline (X
c) depends strongly on the dilution ratio of silane gas by hydrogen gas and substrate temperature (T
s) of deposition, while the grain size (δ) of the microcrystalline is kept conslant irrespective of deposition condition. Preferred orientation changes from (110) to (111) with increasing X
c.
Junction Leakage Current in BF+
2-Implanted, Rapid-Thermal-Annealed Diodes
Authors: Mikoshiba Hiroaki , Abiko Hitoshi , Kanamori Masaru
Published: November 2005

Junction leakage current was studied in shallow p+-n diodes formed by using BF+
2-implantation and rapid thermal annealing (RTA). It is s hown that the bulk leakage component is 3 to 4 times larger in BF+
2-implanted diodes than in B+-implanted diodes. Dislocations created in the BF+
2-implanted layer during the RTA are not the direct cause of this leakage increase. It was also found that the surface leakage component is increased by the RTA. Rapid heat treatment may increase interface states and/or g-r centers in the Si/SiO2 interface layer.
Long-Range Structural Changes in Glass Inducedby Picosecond High-Power Baser Pulses
Authors: Kanemitsu Yoshihiko , Tanaka Yuichi
Published: November 2005

Long-range and delayed structural changes in soda-lime glass and borosilicate crown glass were observed using picosecond high-power laser pulses. Structural changes extended many millimeters beyond the area of laser-induced damage. These changes appeared clearly at 24 h or more after the laser irradiation. Microcracks in the non-irradiated region far outside the central damage region were formed by laser-driven stress. Long-range and delayed structural changes were caused by a chemical interaction of the components of the glass with atmospheric water vapor under stress around these cracks.
Sapphire-Anvil Cell for High Pressure Research
Authors: Furuno Katsuhisa , Onodera Akifumi , Kume Shoichi
Published: November 2005

A pair of sapphire crystals was used for opposed anvils of a high pressure cell. Various types of anvils were attempted. The shapes of all anvils were fundamentally a truncated rod but they differed in minor designs. Maximum pressures of about 14 GPa was attained by the use of anvils with top and bottom surfaces respectively 1 and 5 mm in diameter and with an angle of 18° between the top surface and tapered flank. No particular relation, which is expected to favor the generation of high pressure, was found between the crystallographic axes and the direction of compression.
Selective MOCVD Growth for Application to GaAs/AlGaAs Buried Heterostructure Lasers
Authors: Iwasaki Tamotsu , Matsuo Nozomu , Matsumoto Narihito , Kashiwa Susumu
Published: November 2005

This paper presents the first successful application of a selective MOCVD growth to fabrication of a planar buried heterostructure laser diode. Double heterostructure of GaAs/AlGaAs laser was grown at atmospheric pressure, and the second-step selective growth for making a burying AlGaAs semi-insulating layer was carried out at low pressure. Resistivity of the undoped AlGaAs layer, controlled by changing V/III ratio, was more than 107 Ω·cm at V/III=100. The lasing wavelength was 879 nm and the threshold current of CW operation was 20 mA at room temperature.
A Chemical Etching Process to Obtain Clean InP {001} Surfaces
Authors: Massies Jean , Turco Francoise , Contour Jean-Pierre
Published: November 2005

We report on a new chemical preparation procedure of InP {001} substrates which results in clean, oxide free surfaces, without the need of a high temperature thermal desorption of oxided surface phases. It mainly consists of a deoxidation by HF-ethanol solution, performed on a spinner operated in a nitrogen dry box, after a standard chemical etching using H2SO4/H2O2/H2O mixture. It is shown that such chemically deoxided surfaces are obtained with the typical InP {001} surface reconstructions for a significantly lower annealing temperature than those prepared without this deoxidation step.
Optical-Heterodyne Detection of Mask-to-Wafer Displacement for Fine Alignment
Authors: Itoh Junji , Kanayama Toshihiko
Published: November 2005

The lateral displacement between a mask and a wafer was measured by a newly developed optical-heterodyne method using three symmetrically-arranged gratings. This method is based on variation of the diffraction efficiency of a grating with the polarization of the incident light. With a 0.72 µm-period-grating system and a He–Ne transverse-mode Zeeman laser (wave-length=0.6328 µm), sensitivity better than 1° /0.01 µm was obtained and displacement smaller than 0.005 µm was detected independent of the mask-wafer gap variations. The principle and experimental results are described.
Optical Characterization of Merocyanine Langmuir-Blodgett Layers
Authors: Nishikawa Satoshi , Tokura Yoshinori , Koda Takao , Iriyama Keiji
Published: November 2005

Optical absorption and electro-absorption spectra have been measured on Langmuir-Blodgett films of merocyanine dye in single and double layer configurations. Based on these results, electronic states and microscopic structures of dyemolecules in the first and second layers are discussed.
Distinction of Oxygen and Sulfur in Secondary Ion Mass Spectrometry
Authors: Inoue Kazuyuki
Published: November 2005

The distinction of oxygen and sulfur in secondary ion mass spectrometry has been investigated by nitrogen ion born-bardment, since oxygen and sulfur reciprocally cause interferences of mass numbers. While oxygen and sulfur are detectable by mass numbers 16+ and 32-, respectively, mass number 32- indicates the signal of both oxygen and sulfur whenthe oxygen signal is also provided by mass number 16- due to a high content of oxygen in the specimen. In this situation, the information on sulfur can be obtained by the discrepancy of signals between mass numbers 32- and 16-.
Static and Dynamic Properties of Nonlinear Semiconductor Laser Amplifiers
Authors: Ogasawara Nagaatsu , Ito Ryoichi
Published: November 2005

Optical memory, differential amplification and optical limiting have been experimentally achieved in an AlGaAs laser amplifier, demonstrating the feasibility of nonlinear optical signal processing using semiconductor laser amplifiers. The results of the analysis of the dynamic properties of semiconductor laser amplifiers are also presented; subnanosecond and femto-Joule switching, critical slowing down and output spiking due to self-tuning at the onset of light injection have been analyzed.
Step Smoothing by Radical and Ion Assisted Chemical Vapor Deposition
Authors: Sato Masaaki , Arita Yoshinobu
Published: November 2005

A novel step smooting method called radical and ion assisted chemical vapor deposition (RID), is proposed. In this method, plasma chemical vapor deposition and reactive ion etching occur simultaneously on the surface. The bias sputtering and RID methods are compared and RID is found to provide better step coverage. A silicon oxide deposition experiment is performed in a planar diode-type reactor to verify this method. Experimentation shows that smooth step coverage with rounded edges is obtained for films at room temperature, while high quality films are fabricated at 400°C.
New Resonant Tunneling Diode with a Deep Quantum-Well
Authors: Toyoshima Hideo , Ando Yuji , Okamoto Akihiko , Itoh Tomohiro
Published: November 2005

A new resonant tunneling diode has been fabricated by employing an In0.1Ga0.9As strained layer quantum-well, where its conduction band edge is lower than that of emitter and collector regions. The obtained peak-current voltage is reduced to about 150 mV, which is less than half of that for the diode with a GaAs quantum-well. The high peak-to-valley ratio of 13 is observed at 77 K. This suggests that the peak-current voltage for this structure could be controlled by changing indium composition of the In
y
Ga1-y
As quantum-well, while retaining a large peak-to-valley ratio.
Effects of the Substrate Offset Angle on the Growth of GaAs on Si Substrate
Authors: Ueda Takashi , Nishi Seiji , Kawarada Yoshihiro , Akiyama Masahiro , Kaminishi Katsuzo
Published: November 2005

In the growth of GaAs on Si, the effects of the offset angle of the substrate and its direction on the epitaxial layer were studied using spherical Si substrates. The growth was carried out by a low pressure MOCVD system. On the grown layer, milky lines were observed along the [010] and the [001] axis of the substrate. Except for the narrow regions along these milky lines, the grown layer showed a mirror-like surface with a single domain structure. The surface morphology and the etch pit density in the single domain GaAs layer were strongly affected by the offset direction as well as the offset angle of the substrate.
Vertical-Type Amorphous-Silicon Field-Effect Transistors with Small Parasitic Elements
Authors: Uchida Yasutaka , Watanabe Yoshiaki , Takabatake Masaru , Matsumura Masakiyo
Published: November 2005

1 µm-long vertical-type amorphous-silicon field-effect transistors with small parasitic elements have been fabricated and evaluated. Field-effect mobility, mutual conductance and input capacitance per unit channel width were 0.1 cm2/Vs,10 µS/mm and 0.55 pF/mm, respectively. Cut-off frequency evaluated from these values was 3 MHz.
Pulse Height Distributions of a GM Counter
Authors: Igarashi Ryuji , Narita Yuichi
Published: November 2005

Pulse height distributions of an organic GM counter were investigated. The experiment was so performed that the pulse height held a one-to-one relation with respect to the electric charge released within the counter. Some of the distributions observed showed two or three peaks. This result is a contradiction to that expected from a normal Geiger behavior. In order to interpret the results, various discharge modes and the effect of radiation sources are discussed.
Photoluminescenee from AlGaAs–GaAs Single Quantum Welts with Growth Interrupted Heterointerfaces Grown on GaAs (100) and (311) Substrates at Various Growth Temperatures by Molecular Beam Epitaxy
Authors: Fukunaga Toshiaki , Nakashima Hisao
Published: November 2005

Photoluminescence (PL) measurements at 1.8 K have been carried out for AlGaAs–GaAs single quantum well (SQW) structures grown on GaAs (100) and (311) substrates at various growth temperatures (Tg) by molecular beam epitaxy. Several exciton lines originating from monolayer terrace formation are observed for the SQW grown on (100) surface with 2 min growth interruption (GI) at heterointerfaces under As4pressure. The number of these exciton lines increases withTg, suggesting that the character of columnar growth appears weakly with increasingTg. Fine structures, however, are not observed for SQW's grown on (311)A and (311)B surfaces with 2 min GI at heteroinerfaces. The line widths of PL peaks from SQW's grown on (311)A and (311)B surfaces with GI are significantly larger than those without GI. These facts indicate that the growth mode on (311) surfaces is of much less layer-by-layer character than that on (100) surfaces.
Photolytic Etching of Polycrystalline Silicon in SF6 Atmosphere
Authors: Watanabe Seiichi , Ueda Shinjirou , Nakazato Norio , Takai Mikio
Published: November 2005

Photolytic etching of polycrystalline silicon has been investigated in an SF6 atmosphere. SF6 molecules were excited by one-photon absorption under D2 lamp irradiation. This reaction was found to have high reaction-efficiency, 130 nm/Jcm-2. The distribution of the etch rate in the sample was remarkably influenced by the gas flow. This reaction was thus caused by photo-excitation of SF6 molecules in atmosphere, and not by that of absorbed SF6 molecules over a polycrystalline silicon surface.
Gas Source Molecular Beam Epitaxy of GaP Using PH3 Decomposed by Low Energy Electron Impact
Authors: Uematsu Masashi , Imamura Yoshihiro
Published: November 2005

A low energy electron impact method is proposed to decompose PH3 gas to a phosphorus beam in homoepitaxial growth of GaP. In this method the electrons emitted from a heated tungsten filament bombard PH3 molecules supplied into a cylindrical grid. The growth rate and morphology are studied by changing the electron energy to decompose PH3. The constant growth rate independent of the electron energy proves that the process is found to be Ga-limited growth.
Low Temperature Growth of GaN and AlN on GaAs Utilizing Metalorganics and Hydrazine
Authors: Mizuta Masashi , Fujieda Shinji , Matsumoto Yoshishige , Kawamura Tsutomu
Published: November 2005

The growth and characterization of AlN and GaN on GaAs are presented. Trimethylgallium (TMG) and trimethylaluminum (TMA) were used as group III sources and hydrazine as a nitrogen source. It was found for both nitrides that mass-transport-limited growth took place at high temperature, and that at low temperature the surface catalyzed decomposition of respective metalorganics manifested itself. Deposition of AlN film was observed at as low as 220°C and that of GaN at 450°C both on GaAs substrates. A distinct proof of cubic-form GaN grown on GaAs is obtained from results of the X-ray precession measurement. The <100> direction of GaN on (100) GaAs, however, is slightly tilted from that of the substrate. It is speculated that this tilt results from the very large lattice-mismatch existing between GaN and GaAs.
Diamond-Glass Composite Processing in a Microgravity Condition
Authors: Noma Tatsuo , Tanii Jun , Kuwano Ryushi , Sawaoka Akira B.
Published: November 2005

Diamond-glass composite was fabricated under microgravity in the Challenger, a space shuttle orbiter. Fracture toughness and hardness were compared with the composites fabricated on earth. Under microgravity, uniform distributions in toughness and hardness were obtained. On earth, the values decreased with the distance from the bottom of the crucible.
New SHG Observation in Vinylidene Fluoride/Trifluoroethylene Copolymer Film Using a Pulsed YAG Laser
Authors: Sato Heihachi , Gamo Hideya
Published: November 2005

Second-harmonic generation (SHG) at 0.53 µm has been newly observed in a vinylidene fluoride/trifluoroethylene (VDF/TrFE) copolymer film by using a pulsed Nd:YAG laser.
Growth of Polycrystalline CdS Films by Low-Pressure Metalorganic Chemical Vapor Deposition
Authors: Yamaga Shigeki , Yoshikawa Akihiko , Kasai Haruo
Published: November 2005

Polycrystalline CdS films were grown at temperatures between 50 and 400°C by reacting DMCd and H2S, and the electrical and optical properties of the films were examined. It was found that the films show a preferential orientation to (0001) direction and that their electrical properties are remarkably influenced by the sulphur vacancy. The resistivity of undoped films ranged from 103 to 107 Ω·cm and became maximum at about 250–300°C. Furthermore, the resistivity of the films could be successfully reduced to about 10-1 Ω·cm by doping Al as a donor impurity.