bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of a Channel Electron Multiplier for Detection of Positive Ion
Authors: Takagi Shoji , Kawasumi Yoshiaki , Noda Nobuaki , Fujita Junji
Published: September 2006

The efficiency vs operation voltage characteristics of a channel electron multiplier (CEM) with a negative voltage applied to the entrance cone are investigated in detail. In this negative bias operation, an abnormal increase in efficiency with operation voltage is found, arising from two main mechanisms. One is the change in potential distribution in the cone with the applied voltage. This is because the probability of secondary electrons ejected from the cone being pulled into the channel depends on the potential distribution in the cone. The other is the ionization of particles by leakage electrons from the gap between the CEM exit and the electron collector. Methods of solving these problems are also described.
Optically Detected Magnetic Resonance in Amorphous Semiconductors
Authors: Morigaki Kazuo
Published: September 2006

The principle of optically detected magnetic resonance (ODMR) is briefly described, bearing in mind its application to amorphous semiconductors. The ODMR measurements including those which are time-resolved are reviewed on amorphous semiconductors, particularly on hydrogenated amorphous silicon (a-Si: H). The nature of the recombination centres in a-Si: H is also discussed.
Weak Boundary Storage Effect in Homogeneous Liquid Crystal Cells
Authors: Yang K. H.
Published: September 2006

Based on the Oseen and Frank elastic continuum theory of nematic liquid crystals and on a generalized torque balance equation at the liquid crystal-to-substrate interface, static deformations of a semi-infinite liquid crystal (LC) medium and a homogeneous LC cell have been investigated using the anisotropic LC-to-substrate anchoring energy C as a parameter. Both the elastic and dielectric anisotropies are considered in obtaining the solutions. Storage effects are predicted for sufficiently small anchoring anisotropy. Numerical ranges of C, within which the weak boundary storage effect may occur, have been calculated for twenty commercially-avaialble nematic LC mixtures in the homo-geneous-cell configuration. An equation for the storage time as a function of C has also been derived. The treatment has also been extended to include the most general from of a LC-to-substrate interfacial potential. Such a weak boundary storage effect could provide a means for realizing low power, non-refreshed, matrix-addressed flat panel displays.
Light Propagation in Williams Domains as Analyzed Numerically by Geometrical Optics
Authors: Kondo Katsumi , Arakawa Masahiro , Fukuda Atsuo , Kuze Eiichi
Published: September 2006

We have studied Williams Domain (WD) patterns in detail by observing tomograms with a polarizing optical microscope, confirming the following characteristic features: (1) there are two types of real images, upper and lower; (2) the spacings between the neighboring imaginary image lines are not uniform; and (3) when the focussing plane of the objective is moved above the upper real image or under the imaginary image, the sharp image line splits into two. By taking into account the ray deflection from the wave front normal as well as the focussing effect, we have calculated numerically the characteristic distribution of phase (optical path length) as well as intensity. The results can reproduce the tomograms observed here and the photographs taken by Sato et al. holographically, showing directly the optical path length as the interference fringe patterns.
Influence of Ag Photodoping on Photoinduced Changes in As2S3 Glass Films
Authors: Yaji Tamaki , Kurita Shoichi
Published: September 2006

The transient photoinduced optical absorption change (TOC) and the photodarkening have been studied in Ag photodoped As2S3 glass films. They were observed in all of the sample films which we prepared ((As0.4S0.6)100-X
Ag
X
: 0≦X≦24.4at.%). For the photodarkening, the degree of the change in optical-gap energy due to the light irradiation and the heat treatment decreases with the increasing of Ag content. This may be ascribed to the fact that the motion of S atoms is hindred by the Ag atoms, causing a decrease in spatial flexibility. For the TOC, the spectral distribution of the optical absorption change has a broad peak. The peak center shifts to a lower energy position with the increasing of Ag content.
Critical Voltage Effect in Ni3Fe and FeCo Ordering Alloys
Authors: Matsuhata Hirofumi , Kuroda Kotaro , Tomokiyo Yoshitsugu , Eguchi Tetsuo
Published: September 2006

The critical voltages in ordered and disordered states of Ni3Fe and FeCo alloys were measured for the systematic reflections without superlattice reflections. A small increase in the critical voltage was observed on ordering for the 111 systematic reflections of L12 type Ni3Fe. The temperature factors and the Debye temperatures were evaluated from the measured critical voltages. The changes on ordering in the temperature factors and Debye temperatures were in reasonably good agreement with those derived by X-ray investigation and elastic constants. It is shown that the change in the critical voltage of Ni3Fe is mainly due to the change in the thermal mean-square displacement of atoms. No obvious change in the critical voltage on ordering was detected for 110 systematic reflections of B2 type FeCo.
Recovery of Quenched Cu–Ge Alloys Studied by Positron Annihilation
Authors: Kanazawa Ikuzo , Murakami Hideoki , Kurihara Toshikazu , Sakurai Yoshiharu , Doyama Masao
Published: September 2006

The migration stages of single vacancies and vacancy-Ge atom pairs, and their clustering process are studied in quenched Cu–Ge alloys. The decrease inhparameter is observed from about -70°C to about 0°C in quenched Cu–1.0 at.%Ge alloy, and two mechanisms are proposed for this phenomenon. The increase ofhparameter is observed by the aging from about 250°C to about 400°C. The stage can be deduced to be the growth of clusters of Ge atoms and vacancies, and gaseous bubbles. The presence of three dimensional small clusters of Ge atoms and vacancies, and stability of the clusters are discussed.
Etching Characterization of {001} Semi-Insulating GaAs Wafers
Authors: Okada Yasumasa
Published: September 2006

The characteristics of {001} semi-insulating GaAs wafers have been investigated by the etching/optical microscopy. New etch features such as groove have been revealed in only LEC crystals together with ridge features by an AB etch, but not in boat-grown crystals. The groove features are specifically revealed on gathering and twisting dislocations such as cell or lineage structures, and coincide with each dislocation lying near the surface. Small pits along the ridge features have been revealed in undoped LEC crystal, but not in undoped boat grown crystals. The distribution of the ridge features with the small pits correlates with that of 0.80 eV photoluminescence intensity in the wafer.
Experimental Study on Cylindrical and Spherical Implosions
Authors: Terao Kunio
Published: September 2006

Cylindrically and spherically imploding detonation waves in a stoichiometric propane-oxygen mixture, produced in vessels of about 40 cm internal diameter having different convergent spaces, were experimentally investigated by applying a radially divergent detonation. The experimental results have shown that the ratio of the pressure P behind the imploding detonation waves to the initial mixture pressure P
0 is related to the radial distance r from the implosion center to the detonation front approximately as follows:P/P
0∝r
-0.5 for the cylindrical implosion,P/P
0∝r
-1.0 for the spherical implosion in a conical space, andP/P
0∝r
-1.5 for the spherical implosion in a parabolic space.
The pressure increase with the propagation of the imploding detonation is in every case higher than the theoretical one.
Mechanochemical Effect in ZnTe Powder Associated with Grinding
Authors: Takeuchi Manabu
Published: September 2006

Single crystalline ZnTe powder was mechanically ground in air using an agate mortar and pestle, and changes in the structural and photoconductive properties were studied. The mean particle size was reduced to about 5 µm in the early stage of grinding. In the X-ray diffraction patterns, Te and ZnO lines appeared as 5 h and 8 h grindings, respectively. However, all the diffraction lines disappeared after 50 h grinding. Dark current in the ground ZnTe powder becomes maximum around 8 h grinding. This can be explained by the separation of Te associated with grinding. The original ZnTe powder showed photoconductive sensitivity to visible light. The sensitivity increased slightly in the early stage of grinding and then decreased with further grinding. Temperature dependences of the dark currents were measured in the temperature range of 170–370 K.
Two Pulse and Multiple Position Thomson Scattering System
Authors: Sudo Shigeru , Kondo Katsumi , Mutoh Takashi , Zushi Hideki , Iiyoshi Atsuo , Uo Koji
Published: September 2006

A Thomson scattering system for simultaneous measurements of the electron temperature and density at ten different positions at two times during a single plasma shot has been developed for Heliotron E. The apparatus consists of two ruby lasers, each delivering two pulses whose temporal separation is typically 100 ms; light collection optics including automatic positioning mechanisms; 80 detectors; and a data processing system. We have obtained spatial profiles of T
e (0.05–1.3 keV) and n
e (0.2-9.0×1019 m-3) in Heliotron E for each plasma shot.
Analysis of Disorder Scattering in Ga0.47In0.53As Using Gaussian Potential
Authors: Hiramatsu Kazumasa , Nishinaga Tatau
Published: September 2006

Disorder scattering mobility in Ga0.47In0.53As is calculated by using a sum of two Gaussian potentials; one representing the difference of strong short range core potentials and the other representing the relatively long range potential, the existence of which has been suggested by our previous paper. Approximate calculations are made and a much steeper temperature dependency than the Brooks' disorder scattering mobility is predicted giving good agreement with the recent mobility measurements.
Wave Aberration Testing System for Micro-Lenses by Shearing Interference Method
Authors: Kokubun Yasuo , Usui Tetsuo , Oikawa Masahiro , Iga Kenichi
Published: September 2006

An automatic shearing interference system has been set up incorporating an ITV and a micro-computer in order to reduce measurement errors and shorten job time. The measuring principle and data collection process for the automatic measuring system are described here. The wave aberration of a planar microlens (0.91 mmφ, f=2.06 mm) was measured, and the accuracy of the present system was found to be 8.8% of λ, with the possibility of improvement.
Electrical Investigation of Phase Transition in Black Phosphorus under High Pressure
Authors: Okajima Michio , Endo Shoichi , Akahama Yuichi , Narita Shin-ichiro
Published: September 2006

The electrical resistivity of black phosphorus has been measured under high pressure. Two anomalies are observed at 42 and 108 kbar, associated with the transition from the orthorhombic to the rhombohedral phase and from the rhombohedral to the simple cubic phase, respectively. The former occurs in the vicinity of the vanishing of the energy gap of the orthorhombic phase. The simple cubic phase has a clear positive temperature coefficient of resistivity, but the absolute value of the resistivity is higher than those of usual metals. A preliminary experiment under very high pressure using “sintered-diamond” anvils has shown a sign of a phase transition from the simple cubic phase to a new phase at 0.8–1 Mbar.
Shock Compression and Shock-Induced Radiation Measurements on Calcium Fluoride
Authors: Hasegawa Masaki , Kondo Ken-ichi , Sawaoka Akira
Published: September 2006

Results are presented from a study of a compression wavefront profile for a single crystal of calcium fluoride (CaF2) carried out using a particle velocity gauge. The Hugoniot elastic limit and two polymorphic phase transitions are observed at 1.8 GPa, 5.2 GPa, and 12 GPa, respectively. Shock-induced thermal radiation measurements are also carried out in the shockpressure range from 30 GPa to 70 GPa. A simultaneous spectrometric multichannel analyzer system is developed to observe the shock-induced radiation emitted from a CaF2 crystal. The resultant color temperatures are high, with a small value of emissivity. The pressure dependence of the color temperature behaves anomalously owing to the phase transition, whereas the brightness increases monotonically with increasing pressure.
Estimation of Thermal Diffusivity in an Isotropic Homogeneous Two-Phase System
Authors: Sharma R. G. , Pande R. N. , Chaudhary D. R.
Published: September 2006

A model consisting of a regular distribution of spherical particles of a dispersed phase forming a simple cubic lattice in a continuous phase has been considered in estimating the effective thermal diffusivity (αe) of a homogeneous two-phase (loose material) system. Considering the dispersions of dielectric spheres and conducting spheres, flux modifications have been evaluated using the Green function technique. By choosing the required order interaction and considering the modified thermal diffusivity of individual phases, the effective thermal diffusivities (αe) of two-phase systems have been predicted.
Electronic Properties of Carbon Fibers Intercalated with Copper Chloride
Authors: Oshima Hisashi , Natarajan Venkataramanan , Woollam John A. , Yavrouian Andre , Haugland Edward J. , Tsuzuku Takuro
Published: September 2006

Copper chloride intercalated pitch-based carbon fibers are found to have electrical resistivities as low as 12.9 micro-ohm-cm, and are air, and thermally stable at and above room temperature. This is therefore a good candidate system for conductor application. In addition, we find Shubnikov-deHaas quantum oscillatory effects, and electronic properties of the intercalated fiber are studied using magnetic fields to 20 tesla.
Bubble Generation in Liquid Hydrocarbon in Divergent Fields
Authors: Arii Kiyomitsu , Kitani Isamu
Published: September 2006

The conduction current I
c and the photocurrent I
p were measured in hydrocarbon liquids subjected to d.c. divergent fields. Space-charge limited currents were observed in clarified ionic carrier of both polarities produced by electron attachment. The linear relation between I
p and I
c indicated that molecules were excited by injected electrons before the attachment. In liquid methane in negative point electrode, I
p and I
c were reduced by a rise in pressure, giving evidence for the existence of gaseous bubbles during discharge. However in pentane and hexane, both currents were independent of pressure. The difference is probably caused by the bubble growth rate; the rate is probably larger in liquid methane.
Investigations of Localized States in Hydrogenated Amorphous Silicon
Authors: Huang Fon-Shan , Chang Hua , Chen Jiann-Ruey , Liu Yuen-Chung
Published: September 2006

A novel method is developed to investigate the localized states in the band gap of a-Si:H films by analyzing the photoluminescence spectra. A model of phonon emission process among localized states in long band tail is proposed to interpret the periodic oscillations in the sideband of photoluminescence spectra. For pure film samples of short band tail, thermalization of excited carriers in extended states gives a Gaussian-like photoluminescence spectrum. Rutherford backscattering spectrometry and d.c. conductivity measurement are also performed and analysis on these data conforms the above proposed model.
Fabrication of 1-µm Wavelength Region Ag/p-InP/p-InGaAs Schottky Photodiodes by LPE and Selective Etching
Authors: Takeda Yoshikazu , Takigawa Shin-ichi , Kondo Makoto , Sasaki Akio
Published: September 2006

Photodiodes capable of operating in the 1-µm wavelength region at room temperature were fabricated by LPE and selective etching techniques. The diodes were formed from a p-InGaAs/p-InP/InGaAsP/InP multiple layer, and they correspond to a series connection, both electrical and optical, of an Ag/p-InP Schottky diode and a p-InP/p-InGaAs isotype heterojunction. It was demonstrated that the photoresponse in the 1-µm wavelength region increases drastically with the applied voltage.
Effects of Polar Groups on Electrical Conduction in Polyethylene
Authors: Suzuoki Yasuo , Muto Hirotaka , Cai Guo-xiong , Mizutani Teruyoshi , Ieda Masayuki
Published: September 2006

The effects of polar groups on carrier injection into polyethylene (PE) were studied, using PE films with cast surface layers containing polar groups. The introduction of acetoxy groups mainly enhances positive-carrier injection, whereas that of hydroxyl groups enhances negative-carrier injection. Oxidation products such as carbonyl groups enhance both positive and negative-carrier injection.
An Improved Method of Measuring the Zeeman Shift in Cesium Beam Frequency Standards
Authors: Koga Yasuki
Published: September 2006

An improved method of measuring the Zeeman shift in cesium beam frequency standards is proposed to meet recent accuracy requirements. The method utilizes the frequency separation of a pair of σ transitions with the same absolute value of magnetic quantum number, and has some advantages in comparison with conventional methods. One of these is the linear relation between the measured frequency and the C field strength. In particular, the mean frequency of the pair of σ transitions is shown to be useful for investigating measurement errors. Experimental results are also presented to check the quantitative relation against conventional methods.
Characteristics of Luminescence from InSb Magneto-Infrared-Emitting Diode
Authors: Morimoto Takeshi , Chiba Meiro
Published: September 2006

Utilizing the magnetoconcentration effect due to the Lorentz force in an electron-hole plasma of intrinsic InSb, we have first succeeded in generating an infrared emission having wavelength corresponding to the energy gap with intensity exceeding ∼30 mW/cm2at room temperature with fairly high efficiency. The principle is quite different from usual LED utilizingp-njunction, and so the magneto-diode is especially useful for generation of light with wavelength longer than ∼2 µm at room temperature.
Implication of Amorphous-like Raman Spectra of Gas-Evaporated Si and Ge Microcrystals
Authors: Hayashi Shinji , Abe Hiroya
Published: September 2006

Si and Ge particles prepared by the gas evaporation technique, if sufficiently small show completely amorphouslike Raman spectra. However, high resolution electron micrographs of these particles clearly show lattice fringes, proving that they are crystalline. The amorphous-like Raman signal seems to come from the surface layers of the microcrystals.
Measurement of Grey Zone of a Josephson SFQ Memory Cell
Authors: Harada Naoki , Suzuki Hideo , Hasuo Shinya , Yamaoka Toyoshi
Published: September 2006

Experimental studies of the grey zone of a single flux quantum memory cell using Josephson junctions are described. Probability of the meory cell operating in the grey zone and the dependence of the range of the grey zone on the cell critical current density are measured. From the results, the grey zone range that would produce an erroneous operation probability up to 10-16 is estimated. Results show that the margin of the bias current of the memory cell is 12%. This is 7% less than if the influence of the grey zone is ignored.
A New Insulated-Gate Inverted-Structure Modulation-Doped AlGaAs/GaAs/N–AlGaAs Field-Effect Transistor
Authors: Kinoshita Haruhisa , Sano Yoshiaki , Ishida Toshimasa , Nishi Seiji , Akiyama Masahiro , Kaminishi Katsuzo
Published: September 2006

A new type or modulation-doped AlGaAs/GaAs/N–AlGaAs field-effect transistor with insulated-gate has been successfully fabricated. In this device conducting electrons are both supplied from an n-type AlGaAs layer and accumulated in an MIS structure by electrostatic induction. High gate bias of more than +1.4 V could be applied without a significant leakage current from the gate. Both enhancement-mode (E) and depletion-mode (D) FET's could be fabricated by controlling the gate recess depths. Enhancements of transconductance were observed in E-mode insulated-gate modulation-doped FET's with 1.7 µm gate length by lowering temperature to 77 K. The maximum value obtained at 77 K was 200 mS/mm.
VUV Radiation Bolometer for Beam-Heated Currentless Plasmas in Heliotron-E
Authors: Besshou Sakae , Morimoto Shigeyuki , Motojima Osamu , Obiki Tokuhiro , Iiyoshi Atsuo , Uo Koji
Published: September 2006

We have produced a filtered bolometer for monitoring radiation power in the vacuum ultraviolet region (150 Å–700 Å) to separate photon flux from change exchange neutral particles. The device consists of a thin aluminum filter and a metal film bolometer. It was determined that the VUV radiation carried 30–40% of the total radiated power to the wall under neutral beam injection heating (2 MW, H°→H+).
Structure Analysis of Oval Defect on Molecular Beam Epitaxial GaAs Layer by Cross-Sectional Transmission Electron Microscopy Observation
Authors: Kakibayashi Hiroshi , Nagata Fumio , Katayama Yoshifumi , Shiraki Yasuhiro
Published: September 2006

The fine structure of a surface defect on GaAs grown by molecular beam epitaxy (MBE) is analyzed by transmission electron microscopy (TEM) observing cross-sectional views of the specimen. The defect has a pyramid structure consisting of four {111} stacking fault planes whose Burgers vectors are a
0/6 <112>, a
0/6 <1̄12>, a
0/6 <11̄2> and a
0/6 <\overline112>. Because a defect of this type always starts at the GaAs substrate surface, the origin is thought to be a point defect or atomic contamination on the surface.
Admittance Study of a Single Electron Trap in the LPE InP/InGaAsP Heterostructure Diode
Authors: Takanohashi Tsugunori , Komiya Satoshi , Yamazaki Susumu , Kishi Yutaka , Umebu Itsuo
Published: September 2006

Admittance spectroscopy is applied to the liquid phase epitaxial (LPE) InP/InGaAsP heterostructure diode with a Cd-diffused p+-n junction. A single electron trap is observed in the InP layer. The thermal activation energy is 0.55 eV, and the average capture cross section is 2.7×10-14cm2at temperatures 350 K–440 K. The cut-off frequency of the trap is about 30 Hz at room temperature. The trap concentration shows a sudden increase at the InP/InGaAsP heterointerface.
Stability of Mo Gate MOS Devices Using High Purity Sputtering Target
Authors: Amazawa Takao , Oikawa Hideo , Shiono Noboru , Honma Nakahachiro
Published: September 2006

A Mo (molybdenum) sputtering target with a purity of five nines (99.999%) is developed. The stability of Mo gate MOS devices fabricated using this high purity target is also examined. No mobile charges are observed even in MOS capacitors annealed at 1000°C in nitrogen. The breakdown strength of MOS capacitors with a very thin gate oxide 60 Å thick is held at 12 MV/cm after 1000°C annealing. Long-term stability is also improved using this high purity Mo target.
Metal-Oxide-Semiconductor Characteristics of Chemical Vapor Deposited Cubic-SiC
Authors: Shibahara Kentaro , Nishino Shigehiro , Matsunami Hiroyuki
Published: September 2006

Thermal oxidation of chemical vapor deposited (CVD) cubic-SiC and fabrication of MOS diodes using a thermal oxide film were carried out. The thermal oxide was found to be SiO2 by Auger electron spectroscopic analysis. Capacitance-voltage curves of MOS diodes measured under the dark condition showed deep depletion characteristics. Inversion characteristics were observed under the illuminated condition for the first time.
Origin of the Linear and Nonlinear Piezoresistance Effects in p-Type Silicon
Authors: Suzuki Katuhisa , Hasegawa Hiroshi , Kanda Yozo
Published: September 2006

Origin of the longitudinal and transverse piezoresistance of p-type silicon diffused layers as measured and analyzed by Yamada, Nishihara, Shimada, Tanabe, Shimazoe and Matsuoka is explored theoretically. A model of stress decoupling of the degenerate valence band into two bands of prolate and oblate ellipsoidal energy surface is shown to explain the qualitative feature of anisotropy, temperature dependence and the order of magnitude of the linear coefficients. On this basis, a further comparison is proposed between the model and the nonlinearity for conductivity, so as to establish the origin.
Photocarrier Generation and Transport in Polyimide Films: A Numerical Analysis
Authors: Takai Rashmi , Mizutani Teruyoshi , Ieda Masayuki
Published: September 2006

Differential equations describing the transport of photogenerated charge carriers have been solved numerically to verify a model proposed earlier for the photoinduced decay of the surface potential in polyimide films. According to this model, the photogeneration of charge carriers is of the Onsager type and the succeeding transport is limited by bimolecular recombination. Experimental results for polyimide films have been shown to be in reasonable agreement with this model.
Defect Levels in Thermally-Quenched Silicon Crystals
Authors: Nakashima Kenshiro
Published: September 2006

The energy levels due to quenched-in defects in thermally-treated p-type silicon are analyzed by capacitance transient spectroscopy (DLTS). The quenching rate is found to affect the introduction of several kinds of hole trap, but neither the oxygen concentration nor the dislocation density in the starting materials influences the formation of defects. A hole trap at E
v+0.32 eV, which is not correlated with transition metal impurities such as iron or copper, is found to be introduced efficiently in the rapidly-quenched crystals.
Clustering Parameter and Internal Stress in III-V Ternary Alloys
Authors: Kakimoto Koichi , Katoda Takashi
Published: September 2006

An application of laser Raman Spectroscopy to estimate the clustering parameters and internal stress accumulated in each bond in Ga0.5Al0.5As, Ga0.52In0.48P, Ga1-x
In
x
As (0 ≤x ≤0.53), and GaAs0.7P0.3 is proposed. The clustering parameters and stress are evaluated from the phonon intensity and the difference between the observed optical phonon frequencies and those calculated in terms of the modified RED model, respectively. The estimated values of the clustering parameter agree fairly well with those obtained from theoretical calculation of the excess free energy of mixing. The bond lengths in Ga1-x
In
x
As (0 ≤x ≤0.53) are derived from the stress, and are compared with published data on extended X-ray absorption fine structure.
Effects of Carrier Gas and Substrate on the Electrical Properties of Epitaxial GaAs Grown by the Single Flat Temperature Zone Chloride VPE Method
Authors: Hasegawa Fumio , Yamate Tsutomu , Yamamoto Tadashi , Nannichi Yasuo , Koukitu Akinori , Seki Hisashi
Published: September 2006

The doping profiles and trap levels in the epitaxial layers, and the effect of the carrier gas on the growth were studied for Ga-AsCl3-He-H2 GaAs vapor-phase epitaxy (VPE) with the single flat temperature zone (SFT) method. When inexpensive N2 carrier gas was used instead of He, the growth was more diffusion limited and the mobilities were worse because of contamination from the N2. An anomalous carrier density dip at the epi-substrate interface was observed even in the epitaxial layers grown by the new SFT method, but it was smaller when the growth was kinetically limited, smaller for a liquid-encapsulated Czochrolski (LEC) substrate than for a horizontal Bridgeman (HB) substrate, and could be reduced by gas etching. Many Cu and Fe levels were found at the interface, explaining the dip in the carrier density. Point defects induced at the beginning of the growth are thought to cause these impurities to accumulate at the interface.
Electrical Conductivity Measurement by Acoustic Attenuation in Semi-Insulating GaAs Crystals
Authors: Hirano Ryuichi , Kawai Yoriyoshi , Ogawa Tomoya
Published: September 2006

GaAs crystals are both semiconductive and piezoelectric. In such crystals, acoustic waves induce a piezoelectric field which creates an electric current by causing conduction carriers to flow, resulting in Joule heat and attenuation of the acoustic waves. This means that the attenuation of the acoustic waves corresponds to the conductivity in a GaAs crystal.
Accurate values of the electrical conductivities in various semi-insulating GaAs crystals were obtained using this principie. Ohmic contacts are sometimes very difficult to form on GaAs crystals, but this method requires no contact electrodes. We therefore expect it to prove an extremely useful method of measuring the conductivity of these materials.
Continuous Slowing down Approximation Range of 50 keV to 1000 MeV Positrons
Authors: Pal P. B. , Gupta S. K. , Varshney V. P. , Gupta D. K.
Published: September 2006

The Wilson theory has been modified for the calculation of the continuous slowing down approximation (CSDA) range of positrons. An empirical correction factor P+ has been introduced which depends upon energy and atomic number Z. Calculation for CSDA range of 50 keV to 1000 MeV positrons has been made for elements Z=1 to 92, detector materials, minerals, Organic & Inorganic compounds. The values obtained by the present approach have been shown in good agreement with theoretical values of Berger & Seltzer.
Effect of the Distribution of Free Volume on the β Relaxation in Poly (Vinylidene Fluoride)
Authors: Abe Yoshio , Kakizaki Maeko , Hideshima Teruo
Published: September 2006

A simple theory is presented to explain the temperature variation of the loss permittivity vs frequency curve for the β relaxation in poly (vinylidene fluoride), which is caused by the micro-Brownian motion of amorphous chains. If it is assumed that (1) there exists a distribution of free volume in the amorphous region of the crystalline polymer; (2) the relaxation time for the β relaxation depends on the free volume according to a Doolittle-type equation; (3) the loss permittivity vs frequency curve for a sample without the free-volume distribution is represented by a Williams-Watts decay function with an appropriate parameter, the theory satisfactorily reproduces the characteristics of the experimental loss permittivity vs frequency curve. The application of the theory to the case of mechanical relaxation is also discussed.
Spin-Polarized Scanning Electron Microscopy
Authors: Koike Kazuyuki , Matsuyama Hideo , Todokoro Hideo , Hayakawa Kazunobu
Published: September 2006

The magnetic domains of cobalt (12̄10), iron-silicon (001) and polycrystal iron surfaces have been observed using a spin-polarized scanning electron microscope equipped with a field-emission gun. The new capabilities expected from this microscope have been studied using the clear images obtained.
Effects of Magnetic Field on the Josephson Noise from an SIS Mixer
Authors: Kobayashi Masayoshi , Ohara Shinji , Katsuno Akira , Sakai Kiyomi , Hayashi Yoshikazu
Published: September 2006

The effects of a magnetic field on the noise due to the Josephson current in a superconductor-insulator-superconductor (SIS) mixer were investigated. The noise was found to be suppressed by an applied magnetic field small enough not to affect the DC characteristics of the mixer adversely. The quantum mixing effect between 70 GHz and 10 GHz radiations was clearly observed at bias voltages of 1∼3 mV, as a result of the noise suppression.
Dynamic Mechanism of Fast Switching in Light Valve Using Liquid Crystal
Authors: Sugimura Akihiko , Kawamura Takao
Published: September 2006

A light valve using a liquid crystal previously developed by the authors has a fast switching time of less than 1 ms. The fast switching mechanism of the value is studied theoretically in terms of the static characteristics of light transmission and the transient behavior of the cooperative angular variation of molecules submitted to an electric field. The variation in the light transmission is well explained by an analysis using optical anisotropy. The dynamic mechanism of the fast switching time is also interpreted by the principle of energy conservation related to the elastic, dielectric and viscous torque of the liquid crystal. The analytical results of the static and dynamic characteristics agree well with the experimental results.
Formation of Uniform Solid-Phase Epitaxial CoSi2 Films by Patterning Method
Authors: Ishibashi Kouichirou , Furukawa Seijiro
Published: September 2006

This paper reports that uniform solid-phase epitaxial CoSi2 films without any holes can be fabricated by patterning the Si(111) substrate in the form of squares or stripes before the CoSi2 epitaxial growth. The surface energies of the CoSi2 and Si are considered theoretically. Since the surface energy of the Si(111) surface is smaller than that of the CoSi2(111) surface, the film tends to expose the Si substrate, forming holes in the films. The total surface energy on the patterned area is calculated numerically, showing that the film will be uniform if the pattern size is smaller than a certain critical dimension. The numerical calculations agree qualitatively with the experimental results.
Observation of Sorption of O2 and N2 on Ti Thin Film by DAPS, AEAPS, AES and Electrical Resistance Methods
Authors: Konishi Ryōsuke , Miyada Yoshinori , Sasakura Hiroshi
Published: September 2006

The sorption process of Ti thin films during oxygen and nitrogen exposure has been investigated using a combination of DAPS, AEAPS, AES and electrical resistance measurements.
In the case of oxygen exposure, oxygen atoms diffuse into layers up to 3–5 Å beneath the surface at an exposure of 4L. Further exposure of 5–100L enhances the diffusion, probably to a depth of 6–10 Å. Furthermore, comparison of DAPS and AEAPS measurements shows that a stable surface oxidation layer is formed in the 6–10 Å layer at an exposure of 100L.
In the case of nitrogen exposure, nitrogen atoms adsorb on the surface at 3–4L. After that, nitrogen atoms diffuse into the layer 6–10 Å below the surface at exposure of 7–10L, followed by saturation.
The saturation value of the diffusion depth of nitrogen atoms in Ti thin films is found to be much smaller than that of oxygen atoms.
Effect of Cs Adsorption on Surface Impedance of Thermally-Cleaned Si(111)7×7 Wafer
Authors: He Li , Yasunaga Hitoshi
Published: September 2006

The effect of cesium adsorption on a thermally-cleaned wafer Si(111)7×7 surface was investigated by measuring the changes in the surface conductivity and capacitance in parallel. It is deduced from the results that a p-type region below the surface was formed in the Si wafer regardless of the type of conduction when it was heated up to 1500 K. The p-type region was 68 to 7 µm thick with an acceptor concentration of 1015 to 1016 cm-3 in n-type Si. Electrical conduction was observed in the Cs overlayer with coverages of more than 2.4×1014 atoms·cm-2. The overall dependence of the surface impedance upon the Cs coverage and frequency are well understood qualitatively.
Surface Microtopography and Compositional Change of Cesium-Ion-Bombarded Semiconductor Surfaces
Authors: Homma Yoshikazu , Okamoto Hamao , Ishii Yoshikazu
Published: September 2006

This paper discusses the surface topography and compositional change of the surfaces of cesium-ion-bombarded Si, GaAs and InP. Microtopographies of ∼0.1 µm are observed in all of these samples, even in the early stage of sputtering. Microtopographies are formed through oxidation of the cesium-containing surface in air. In compound semiconductors, the altered layer formed by preferential sputtering plays an important role in microtopography development. Especially in InP, microtopography is observed under both argon and oxygen ion bombardments as well as under cesium-ion bombardment. The high vapor pressure of phosphorus is thought to be responsible for the formation of the altered layer.
Influence of Energetic Oxygen Bombardment on Conductive ZnO Films
Authors: Tominaga Kikuo , Yuasa Takayuki , Kume Michiya , Tada Osamu
Published: September 2006

Conductive ZnO films were prepared by DC planar magnetron sputtering and DC diode sputtering, and the reason for the high resistivity shown by the films at the substrate positions facing the eroded area of the target was investigated. It was found that bombardment of the film by energetic O atoms or O-ions is responsible for the high film resistivity, since this results in a decrease in both the carrier mobility and the carrier concentration. The arrival of excess O atoms and O-ions with relatively lower energies also induces an increase in the film resistivity as a result of a decrease in carrier concentration. The positional dependence of the film resistivity is explained by considering the above two factors.
Consideration on Filamentary Thermal Breakdown by Measuring Pre-Breakdown Current in Solid Dielectrics
Authors: Hikita Masayuki , Kanno Ippei , Sawa Goro , Ieda Masayuki
Published: September 2006

Filamentary thermal breakdown is discussed on the basis of experimental results on the electrical conduction just prior to breakdown in polyimide (PI) and polyethylene (PE) with a dc ramp voltage applied at 90°C. In PI, the pre-breakdown current was almost proportional to the electrode area S till about 100 µs before breakdown, but a sharp current increase then appeared at smaller values of S. In PE, this sharp current increase could be detected only after about 25 ns before breakdown, using a new measuring device with higher time resolution. Assuming that this sharp current increase is due to the temperature rise of a small spot in the sample leading to filamentary thermal breakdown, the maximum radius of the filament spot was estimated at about 35 µm for PI and about 2000 Å for PE.
Thermal Behavior of Stacking Faults in Silver Films
Authors: Jr. Schwab S. Major, , Grosskreutz J. C.
Published: September 2006

Stacking faults in silver films were observed by transmission electron microscopy over the temperature range 300° to 740°K. No significant change was observed in fault width. The results reported here for growth faults substantially are the same as results reported elsewhere for deformation faults. It was concluded that the thermal behavior of the widths of stacking faults in silver is independent of prior history and present boundary conditions.
Nuclear Magnetic Resonance and Dielectric Dispersion of Polytetrahydrofuran and Poly-1, 3-dioxolane
Authors: Tsutsumi Akihiro , Hikichi Kunio , Kaneko Motozo
Published: September 2006

Broad line nuclear magnetic resonance measurements were made over a wide temperature range from 77°K. to the melting point for polytetrahydrofuran and poly–1, 3–dioxolane. The NMR spectra showed two components at room temperature, broad and narrow, and these were attributed to crystalline and disordered regions, respectively. At room temperature, second moment of the broad component calculated by separating the narrow one was considerably smaller than that at 77°K. for both polymers. This indicates the presence of the molecular motion in crysralline. Dielectric measurements were also made for poly–1, 3–dioxolane. Two relaxation processes were observed corresponding to the glass transition and the local mode. The dielectric data of this polymer indicates that its molecular conformation is not planar zig-zag.
The Properties of the Interface between Gallium Arsenide and Silicon Oxides
Authors: Sato Yasuo
Published: September 2006

The MOS characteristics of gallium arsenide were investigated using silicon monoxide and dioxide as insulators. The band scheme was nearly flat at the surface of gallium arsenide covered by these oxides. At the interface, there were several kinds of surface state whose levels were located at 0.05, 0.2, 0.4, 0.55 and 0.65 eV below the conduction band edge respectively. Densities of these states were estimated as about 2∼5×1011/cm2.
Far-Infrared Germanium Detectors
Authors: Oka Yasuo , Nagasaka Keigo , Narita Shin-ichiro
Published: September 2006

Two types of far-infrared Ge detectors have been investigated. One is a photoconductivity-type detector, utilizing photo-excitations from the shallow donors (Sb) or acceptors (In) in Ge. The impurity concentration of this type in the range from 6×1014cm-3to 5×1015cm-3. These detectors exhibit photoresponse over the wavelength region of 50∼120 µ and their response-time is less than 1 µsec. The other detector is of bolometer type, making use of energy absorption by the free carriers of the impurity conduction. The concentration of In impurity is about 7×1016cm-3. The detector of this type has a photoresponse over the wavelengths of 20∼1000 µ and the response-time is about 300 µsec.
Holographic Measurement of Optical Transfer Functions
Authors: Matsumoto Kazuya , Ose Teruji
Published: September 2006

Two identical holograms are set in parallel with each other giving some amount of lateral shear. The total flux of light which is diffracted from these holograms in the direction of the first order shows the auto-correlation of the complex amplitude recorded in the holograms. As a merit of this method the sinusoidal amplitude modulation of the flux to be measured is automatically introduced by the shear with a constant speed. The method is applied to the measurement of optical transfer function of a spatial phase filter.
Diffuse Illumination in Two-Beam Fraunhofer Holography and Spatial Filtering Effect
Authors: Asakura Toshimitsu
Published: September 2006

The effect of diffuse illumination on two-beam Fraunhofer holography is investigated experimentally using a Mach-Zehnder interferometer modified for obtaining a hologram. Reconstructed images are compared with the theory and discussed under the relation with the distortion term. The improvement of image degradation due to the distortion term is shown by means of diffuse illumination. When diffuse illumination is not employed in the hologram-making process, there appears in the reconstructed images the spatial filtering effect which can, however, be avoided using diffuse illumination. Detailed discussions on this filtering effect in a hologram are conducted.
A Magnetostrictive Load Cell for Use under High Hydrostatic Pressures
Authors: Oguchi Atsushi , Yoshida Susumu
Published: September 2006

A load cell utilizing magnetostrictive strain gauges which is suitable for measuring loads up to 300 kg in tensile testing of materials under high hydrostatic pressures up to 15000 kg/cm2 is described. Temperature and pressure variations during tensile testing can be completely compensated by the use of a dummy gauge. The calibration of the load cell under pressure is performed by a coil spring which is calibrated at atmospheric pressure. The calibration curves under pressures up to 13400 kg/cm2 and 200 kg agree with the atmospheric calibration curve within 2%.
Preconditioning: The Mitochondrial Connection
Authors: Murphy Elizabeth , Steenbergen Charles
Published: September 2006

Over the past decade there has been considerable progress in elucidating the signaling pathways involved in cardioprotection. Considerable recent data suggest that many of these signaling pathways converge on the mitochondria, where such pathways alter the activity of key mitochondrial proteins, leading to reduced apoptosis and necrosis. Inhibition of the mitochondrial permeability transition pore is emerging as a central mechanism in cardioprotection. This review focuses on mechanisms by which cardioprotection alters mitochondrial proteins and channels that regulate cell death and survival.
Interactions between Na+ channels and Na+-HCO3− cotransporters in the freshwater fish gill MR cell: a model for transepithelial Na+ uptake
Authors: Parks Scott K. , Tresguerres Martin , Goss Greg G.
Published: September 2006

Isolated mitochondria-rich (MR) cells from the rainbow trout gill epithelium were subjected to intracellular pH (pHi) imaging with the pH-sensitive dye BCECF-AM. MR cells were categorized into two distinct functional subtypes based on their ability to recover pHi from an NH4Cl-induced acidification in the absence of Na+. An apparent link between resting pHi and Na+-independent pHi recovery was made. We observed a unique pHi acidification event that was induced by extracellular Na+ addition. This further classified the mixed MR cell population into two functional subtypes: the majority of cells (77%) demonstrated the Na+-induced pHi acidification, whereas the minority (23%) demonstrated an alkalinization of pHi under the same circumstances. The focus of this study was placed on the Na+-induced acidification and pharmacological analysis via the use of amiloride and phenamil, which revealed that Na+ uptake was responsible for the intracellular acidification. Further experiments revealed that pHi acidification could be abolished when Na+ was allowed entry into the cell, but the activity of an electrogenic Na+-HCO3− cotransporter (NBC) was inhibited by DIDS. The electrogenic NBC activity was supported by a DIDS-sensitive, Na+-induced membrane potential depolarization as observed via imaging of the voltage-sensitive dye bis-oxonol. We also demonstrated NBC immunoreactivity via Western blotting and immunohistochemistry in gill tissue. We propose a model for transepithelial Na+ uptake occurring via an apical Na+ channel linked to a basolateral, electrogenic NBC in one subpopulation of MR cells.
Expression and localization of monocarboxylate transporters and sodium/proton exchangers in bovine rumen epithelium
Authors: Graham C. , Gatherar I. , Haslam I. , Glanville M. , Simmons N. L.
Published: September 2006

Monocarboxylate-H+ cotransporters, such as monocarboxylate transporter (MCT) SLC16A, have been suggested to mediate transruminal fluxes of short-chain fatty acids, ketone bodies, and lactate. Using an RT-PCR approach, we demonstrate expression of MCT1 (SLC16A1) and MCT2 (SLC16A7) mRNA in isolated bovine rumen epithelium. cDNA sequence from these PCR products combined with overlapping expressed sequence tag data allowed compilation of the complete open reading frames for MCT1 and MCT2. Immunohistochemical localization of MCT1 shows plasma membrane staining in cells of the stratum basale, with intense staining of the basal aspects of the cells. Immunostaining decreased in the cell layers toward the rumen lumen, with weak staining in the stratum spinsoum. Immunostaining in the stratum granulosum and stratum corneum was essentially negative. Since monocarboxylate transport will load the cytosol with acid, expression and location of Na+/H+ exchanger (NHE) family members within the rumen epithelium were determined. RT-PCR demonstrates expression of multiple NHE family members, including NHE1, NHE2, NHE3, and NHE8. In contrast to MCT1, immunostaining showed that NHE1 was predominantly localized to the stratum granulosum, with a progressive decrease toward the stratum basale. NHE2 immunostaining was observed mainly at an intracellular location in the stratum basale, stratum spinosum, and stratum granulosum. Given the anatomic localization of MCT1, NHE1, and NHE2, the mechanism of transruminal short-chain fatty acid, ketone body, and lactate transfer is discussed in relation to a functional model of the rumen epithelium comprising an apical permeability barrier at the stratum granulosum, with a cell syncitium linking the stratum granulosum to the blood-facing stratum basale.