bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Simulation of Slow Positron Accumulator
Authors: Kinugawa Tohru , Arikawa Tatsuo
Published: November 2005

Computer simulation experiments were carried out to verify the principle of a proposed intense slow positron accumulator. The accumulator employs an axially symmetric monotonously decreasing magnetic field as a guide field whose vector potential has an almost flat-top-maximum with a slight dip around the equilibrium orbit for beam accumulation. Two types of trapping mechanisms for the slow positron beam into this equilibrium orbit were investigated by means of applying a time-varying electric field either in the radial or azimuthal direction. Characteristic quantities of the accumulated beam are also discussed.
Spectral Analysis of Deep Level Transient Spectroscopy (SADLTS)
Authors: Morimoto Jun , Fudamoto Michihiro , Tahira Kenichiro , Kida Tatsuo , Kato Seiji , Miyakawa Toru
Published: November 2005

A spectral analysis of Deep Level Transient Spectroscopy (SADLTS) is proposed. This method analyzes the transient junction capacitance C(t)=\int
b

a

S(λ)exp
(-λ·t)dλ in order to determine the finite continuous emission rate spectrum S(λ). SADLTS permits one to obtain more detailed information with a single-temperature scan and spectral analysis instead of the conventional multi-temperature scan or single-exponential analysis. Even if S(λ) includes two peaks at λ1 and λ2, those peaks can be distinguished for λ2/λ1>2.
As an example of the application of SADLTS, deep levels in Si:Au were experimentally investigated. According to the three-dimensional S(λ)-T
2/λ-1/T representation, the apparent single peak in the conventional DLTS was found toconsist of two adjacent levels with activation energies and capture cross sections of E
B1=0.51 eV, σB1=4.0×10-15 cm2 and E
B2=0.47 eV, σB2=1.1×10-15 cm2, respectively.
Critical Current Density of Y–Ba–Cu Oxide Wires
Authors: Kohno Osamu , Ikeno Yoshimitsu , Sadakata Nobuyuki , Aoki Shinya , Sugimoto Masaru , Nakagawa Mikio
Published: November 2005

We have prepared Y–Ba–Cu oxide superconducting wires with stainless-steel, Cu–Ni alloy or silver sheath by a powder metallurgy technique, and confirmed superconductivity in stainless-steel or silver-sheathed wires. During the hea-treatment, a dielectric layer was formed at the interface between the sheath and Y–Ba–Cu oxide in stainless-steel-sheathed and Cu–Ni alloy-sheathed wires. The diffusion of the sheath element into Y–Ba–Cu oxide was analyzed using EPMA. The highest critical current dernsity, 560 A/cm2, was obtained for a silver-sheathed wire which was heat-treated in oxygen flow. A multicored wire was produced.
Si Etching with a Hot SF6 Beam and the Etching Mechanism
Authors: Suzuki Keizo , Ninomiya Ken , Nishimatsu Shigeru , Okada Osami
Published: November 2005

Silicon surface etching using a hot SF6 (SF6
*) molecular beam is being investigated in the interest of studying the influence of vibrational energy on surface reactions and developing a damage-free etching technique. The SF6
* beam is produced by the free jet expansion of SF6 gas heated in a quartz furnace. It is seen that SF6
* vibrational energy enhances the Si etch rate. It is also shown that the Arrhenius model modified to take the vibrational energy effect into account can explain the experimental results. The model parameters are then determined to be 6500 cm-1 for activation energy (E
a), 0.17 for the efficiency (α) of the vibrational energy used to clear the activation energy barrier, and 5.0 for the frequency factor (A).
Solar Cell Characteristics of High-Efficiency Polycrystalline Silicon Solar Cells Using SOG-Cast Wafers
Authors: Shimokawa Ryuichi , Nishida Keiichi , Suzuki Akio , Hayashi Yutaka
Published: November 2005

Very-high-efficiency large-area SOG-cast silicon cells with over 14% efficiency were fabricated and analyzed in order to identify efficiency loss mechanisms. A number of small-area mini-cells were fabricated from the 10×10 cm2 cell, and their illuminated and dark J-V characteristics were investigated as a function of position, including the grain boundaries. The effect of the grain boundary on the J-V characteristics was quantitatively determined using the mini-cell technique. Also, a possibility of obtaining large-area SOG silicon cells with over 16% efficiency was indicated after the investigation of the spatial homogeneity.
Energy-Band Offset of In0.53Ga0.47As–In0.52(Ga1-xAIx)0.48As Heterostructures, Determined by Photoluminescenee Excitation Spectroscopy of Quasi-Parabolie Quantum Wells Grown by MBE
Authors: Sandhu Adarsh , Nakata Yoshiaki , Sasa Sigehiko , Kodama Kunihiko , Hiyamizu Satoshi
Published: November 2005

The conduction-band discontinuity, ΔE
c(x), of In0.53Ga0.47As–In0.52(Ga1-x
Al
x
)0.48As heterostructures was determinedto be ΔE
c(x)=(0.73±0.03)ΔE
g(x) (0\leqslantx\leqslant1), by a comparison of the electron (and hole) energy levels in quasi-parabolic (multi-stepped) In0.53Ga0.47As–In0.52(Ga1-x
Al
x
)0.48 As quantum welts observed by photoluminescence excitation spectroscopy, with numerical solutions of Schrödinger's equation, where non-parabolicity of the conduction band was considered.
DC Gas-Discharge Display Panel with LaB6 Thin-Film Cathode
Authors: Okamoto Yukio , Aida Toshiyuki , Shinada Shinichi
Published: November 2005

A dc gas-discharge display panel with LaB6 thin-film cathodes is proposed for data information systems. A thin-film, having a crystallographic orientation of [100], was formed on a Ni thick-film using the electron-beam evaporation technique. The low work function of the crystallographic orientation provided a low operating voltage. The normal cathode fall potential for the thin-film cathode in a Ne+Ar (0.4%) gas discharge was approximately 80 V, about 1/2 that of the commonly used Ni thick-film cathode. The display panel consisted of two glass plates: cathodes were formed on one plate (substrate) and anodes on the other. The cathodes and anodes were perpendicular to each other, and were separated by barriers formed in parallel between the anodes. Low voltage, high luminance, high luminous efficiency and stable operation were attained without the use of Hg.
Generation of a Large Swelling in the Spatial Magnetic Field Profile near the Coil Axis of a Theta Pinch
Authors: Ogi Sukeomi , Shiratani Masaharu , Watanabe Yukio
Published: November 2005

A large magnetic field swelling near the coil axis in a theta pinch with low discharge energy was investigated in detail by changing the gas-fill pressure, the kind of gas and the intensity of the applied magnetic field. Under the experimental conditions, the maximum magnetic field around the axis amounted to more than three times the applied field. It was experimentally clarified that the shifting of the plowed plasma to the back of the current sheath in the implosion phase is essential for the phenomenon and that the amplitude of the field around the axis can be explained by the flux trapped by the shifted plasma.
Higher-Order-Mode Damping Coupler for Beam Instability Suppression
Authors: Izawa Masaaki , Kobayakawa Hisashi , Sakanaka Shyogo , Tokumoto Shuichi
Published: November 2005

The effects of a higher-order-mode damping coupler on coupled-bunch instabilities were studied in the Photon Factory storage ring. It was inserted in the RF accelerating cavity in order to suppress higher-order modes, especially the TM011-like mode excitation which causes a longitudinal coupled-bunch instability. Threshold currents of this beam instability were measured before and after insertion. The results showed the obvious damping effects: instability thresholds were largely improved. No practical problems, such as discharge or vacuum trouble were observed during operation with a high-current beam and a single-bunched beam.
Photocurrent Spectra of Phthalocyanine Films in Relation to Excited State Properties
Authors: Minami Nobutsugu , Asai Michihiko
Published: November 2005

Photocurrent spectra of thin-film sandwich cells of vacuum-deposited phthalocyanines (Pc's) have been investigated and compared with their optical absorption spectra. A close resemblance was found between the two spectra for H2Pc and ZnPc, but peaks in the photocurrent spectra of CuPc and NiPc have been found to be considerably shifted compared with those in the absorption spectra. These photocurrent peaks in CuPc and NiPc correspond well to structures in the recently reported electroabsorption spectra of phthalocyanines. Direct charge-transfer excitation is suggested to play a role in the photocarrier generation in phthalocyanine films. The absorption spectrum of VOPc is considerably dependent on the deposition conditions of thin films, unlike other planar phthalocyanines.
Noncontact Measurement of Film Thickness by the Photothermal Deflection Method
Authors: Fujimori Haruo , Asakura Yamato , Suzuki Kazumichi , Uchida Shunsuke
Published: November 2005

A noncontact film-thickness measurement method using photothermal deflection was studied from theoretical and experimental results of the film-thickness dependency of the deflection amplitude. The calculated results showed that thicknesses in a range from the skin depth to the thermal-diffusion length of an opaque film could be determined from the deflection amplitude, which increased monotonously in that range. It was shown that the thicknesses of a transparent film could be determined from the vibrational structure of the deflection amplitude due to an interference effect of the excitation beam or from its decrease by an adiabatic effect of the film. Experimental results for NiO films (3–38 µm) and SiO2 films (20–110 nm) revealed the possibility of noncontact film-thickness measurements in air and water.
A Soft X-Ray Microprobe Using an Axisymmetric Tandem Toroidal Mirror
Authors: Aoki Sadao , Yamaji Hironao
Published: November 2005

An axisymmetric tandem toroidal mirror has been designed and fabricated for a soft X-ray microprobe. We present the design as well as the focusing characteristics, evaluated by a ray trace procedure. The mirror has been used with an AlKα (λ=8.34Å) source to produce demagnified images and to form a microprobe for soft X-ray scanning microscopy. We present these results and their analysis.
Analysis of Mechanical Aberrations in the Eleclrostatic Deflector
Authors: Tsumagari Takashi , Murakami Jun , Ohiwa Hajime , Noda Tamotsu
Published: November 2005

A third-order aberration formula of mechanical aberrations due to various errors in assembling or machining of the electrostatic deflector is derived from a second-order perturbation theory. Mechanical aberrations in a magnetic focusing and electrostatic deflection system are analyzed by utilizing this new formula.
The results show that the electrostatic deflector suffers, in general, more serious effects from errors in machining than in assembling if the error magnitudes are almost the same, and also that the edge of the deflection electrodes where the electric field concentrates exerts a greater influence upon occurrence of mechanical aberrations than other portions with less electric field. It is also ascertained that the octopole deflector is much superior to the quadrupole regarding misalignment through numerical comparison between both deflectors.
Focused-Ion-Beam Broadening Due to Collisions with Residual Gas Atoms
Authors: Ishitani Tohru , Kawanami Yoshimi , Shukuri Shoji
Published: November 2005

Focused-ion-beam (FIB) broadening was investigated from the viewpoint of FIB collisiouts with residual gas. Broadening was found analytically to be proportional to r
-2(m+1), where r is the radial distance and m is the potential parameter. The 70 keV B+-FIB profile was measured resist exposure. The experimental results provide qualitative support for the present analytical method. Other causes for FIB broadening are also discussed.
Formation of Intermetallic Compounds in Al Thin Films Vapor-Deposited on Au Plate
Authors: Kato Hiroshi
Published: November 2005

This paper concerns the measurement of infrared radiance from an Al thin-film surface vapor-deposited on an Au plate in order to investigate the formation and growth of Al–Au intermetallic compounds in the film. The emissivity of the Al–Au alloy is found to increase with an increase in the Au stoichiometry. A step variation of the surface radiance during annealing is also observed. This has been understood to result from the Al2Au phase appearing on the film first, followed by the alloy, with smaller Al stoichiometry and finally by the AlAu4 phase covering the surface. The activation energies for the movement of the boundaries between two phases due to the growth of the Al2Au and AlAu4 phases through the film were 22.8 kcal/mol (Al/Al2Au) and 22.2 kcal/mol (Al2Au/AlAu4), respectively.
Small Angle Scattering of Neutrons and X-Rays from Aqueous Dispersions of Dipalmitoyl Phosphatidylcholine
Authors: Takeda Takayoshi , Akabori Kozo , Toyoshima Yoshinori , Komura Shigehiro , Takebe Yumi
Published: November 2005

SANS and SAXS from aqueous dispersions of DPPC and Egg-PC were measured at temperatures in the range from 20 to 50°C. The SANS patterns in the Egg-PC-D2O system changed little with the temperature T. On the other hand, the SANS patterns in the DPPC-D2O system changed drastically at the main transition temperature T
m2; the diffraction peak which corresponds to the repeat distance of the lipid bilayers was observed above T
m2, but below T
m2 it disappeared and a large diffuse scattering appeared. On the contrary, such a drastic change at T
m2 was not observed in SAXS measurementson the DPPC-D2O system and the DPPC-H2O system; distinct diffraction peaks were observed, but such a large diffuse scattering as was found for SANS was not observed, even below T
m2. The origin of the difference between the results of SANS and those of SAXS is interpreted in terms of the difference of the form factor of both scatterings.
One-Dimensional Model of Bubble Growth and Liquid Flow in Bubble Jet Printers
Authors: Asai Akira , Hara Toshitami , Endo Ichiro
Published: November 2005

The model is based on a one-dimensional heat conduction equation, an equilibrium pressure-temperature relation, energy and mass conservation relations and a hydraulic equation. Numerical results showed a good agreement with an experiment under typical operating conditions of a bubble jet printer with water-based ink. The bubble-generation temperature was estimated to be ∼270°C, which is close to the experimentally obtained superheat limit of water. The initial bubble pressure was estimated to be ∼4.5 MPa, but it decreases to less than ∼10 kPa in 10 µs. This rapid decrease of pressure explains the cavitational action of the bubble, observed in actual bubble jet operations. Effects of ink viscosity, nozzle outlet length and operating voltage were investigated using the model. The results provide a basic guide to the design of bubble jet printers.
Magnetic Properties of Rapidly Quenched Nd10Fe85-xTxB5 (T=Zr, Nb) Alloys
Authors: Kohmoto Osamu , Yoneyama Tetsuhito , Yajima Koichi
Published: November 2005

Magnetic properties were studied for Nd10Fe85-x
T
x
B5(T=Zr, Nb; x=0, 4) alloys, which were first rapidly quenched and then crystallized by heat treatment. An energy product of (B
H)max=12.2 MGOe, coercive force of i
H
c=9.2 kOe, and remanence of B
r=8.2 kG were achieved in a Nd10Fe81Zr4B5 alloy; the Nd content is the lowest ever reported for a Nd–Fe–B alloy having a high-energy product.
Simulations of Switching Behavior in a Ferroelectric Liquid Crystal
Authors: Yamada Yuichiro , Tsuge Tatsuya , Yamamoto Norio , Yamawaki Masao , Orihara Hiroshi , Ishibashi Yoshihiro
Published: November 2005

Simulations of the switching behavior in a ferroelectric liquid crystal were carried out with the model proposed by Handschy and Clark. There appear to be various types of switching processes for changing surface anchoring force. Results of simulations are compared with experimental observations, some of which seem to be well reproduced by the Handschy-Clark model.
Si Surface Cleaning by Si2H6–H2 Gas Etching and Its Effects on Solid-Phase Epitaxy
Authors: Kunii Yasuo , Sakakibara Yutaka
Published: November 2005

Si surface cleaning with Si2H6–H2 was studied for lateral solid-phase epitaxy (L-SPE) of CVD a-Si films. The cleaning was performed at 850°C, which is considerably lower than the previously-reported H2-cleaning temperature (1100°C). This is because etching of native oxide is enhanced by a reaction between oxide and Si-atoms dissociated from Si2H6. The effects of Si2H6-cleaning on L-SPE were studied using a Si (100) wafer with SiO2 stripes. After Si2H6-cleaning or H2-cleaning at 850°C, CVD a-Si films are deposited on the wafers, then crystallized by annealing (575°C). An H2-cleaned sample showed imperfect L-SPE because of a residual native-oxide layer at the a-Si / substrate interface. In the Si2H6-cleaned sample, the native-oxide layer was removed, and L-SPE growth was observed uniformly in the wafer. Si2H6-cleaning at 850°C is applicable for substrates with abrupt impurity distribution.
Oxygen-Doped Si Epitaxial Film (OXSEF)
Authors: Tabe Michiharu , Takahashi Mitsutoshi , Sakakibara Yutaka
Published: November 2005

We propose a new wide-gap material, an oxygen-doped Si epitaxial film (OXSEF), for applications to Si heterobipolar transistors (HBTs). OXSEF containing several tens of at.% of oxygen can be grown on a Si substrate by depositing Si in about 10-6 Torr O2. OXSEF is literally almost a single crystal with an identical crystalline structure to Si, although it includes {111} twins as defects caused by oxygen. Temperature and O2 pressure dependences of oxygen concentration in OXSEF are dominated by oxygen adsorption on the Si surface. Oxygen atoms in OXSEF segregate to some extent toform incomplete oxides like SiO1.5, but complete phase separation as a mixture of Si and SiO2. regions does not occur, probably bcause of non-equilibrium conditions in MBE growth. Valence band discontinuity at the Si/OXSEF interface is deduced to be 0.26 eV based on photoelectrical measurements.
Strong-Coupling Theory of Superconductive Electron-Electron Interaction for High-Tc Oxide Superconductors
Authors: Soda Toshio
Published: November 2005

We discuss the role of the spin exchange interaction for high- T
c Y–Ba type copper oxide superconductors. We then formulate a strong-coupling theory for our recently proposed mechanism for high-T
c oxide superconductors by a two-band model of lighter and heavier electrons while taking into account an infrared divergent effect due to the Fermi surface of the lighter electrons. We show how to theoretically derive a very high experimental ratio, twice the energy gap at T=0, over the transition temperature, 2Δ(0)/k
T
c, to be in the range from 4.5 to 7.5.
High Voltage Thyristor Pulser for Spark Gap Switches
Authors: Fukuta Masahiro , Naito Koji , Ishii Akira , Okamoto Hiroaki , Ishii Shozo
Published: November 2005

A compact inexpensive high voltage thyristor pulser is developed. The output voltage of the pulser is stepped up to more than 10 kV with pulse transformer. The ramp rate of the secondary terminal voltage is 7 kV/µs. The pulser is used for triggering spark gap switches in fast discharge experiments. The total time jitter of the discharge system is less than 50 ns. Several techniques are employed to improve the noise margin.
Minority Carrier Transport in Heavily Doped Silicon: Fundamental Equations
Authors: Alamo Jesús A. del , Swanson Richard M.
Published: November 2005

From fundamental principles, the equations that govern minority carrier transport and recombination in a heavily doped semiconductor are derived. The equations are based on three physically meaningful doping-dependent material parameters: minority carrier lifetime, mobility, and equilibrium concentration. To completely describe the problem, there is no need to use nonphysical entities like “effective doping level” or “apparent bandgap narrowing”, as has become common in the silicon device literature. Under steady state, only two parameters, which are combinations of the three fundamental ones, are relevant to minority carrier transport and recombination. These findings have important implications for parameter measurements and for the modelling of heavily doped regions in devices.
Measurement of Electron Cyclotron Emission from the Tandem Mirror GAMMA 10
Authors: Mase Atsushi , Koseki Tadashi , Itakura Akiyosi , Higaki Naoshi , Jeong Jung H. , Cho Teruji , Ishii Kameo , Miyoshi Syoichi
Published: November 2005

Electron cyclotron emission (ECE) measurements on the tandem mirror GAMMA 10 are reported. The fifth-harmonic ECE in the thermal barrier region was measured in order to obtain the temporal and spatial evolution of hot electrons produced by electron cyclotron resonance heating for the formation of a thermal barrier potential well. The electron temperatures in the central and plug cells were determined using the second-harmonic ECE which was corrected for the hot-electron emission by considering a relativistic shift of resonance layers. The results, thus obtained, show strong evidence for the existence of a thermal barrier.
Electrodeposited Films from Aqueous Tungstic Acid-Hydrogen Peroxide Solutions for Electrochromic Display Devices
Authors: Yamanaka Kazusuke
Published: November 2005

Electrodeposited tungsten oxide films from aqueous tungstic acid-hydrogen peroxide solutions were investigated for applications to electrochromic devices. These films exhibited electrochromism in aprotic electrolyte solutions containing Li-salts. When the films were heat-treated for an hour at temperatures between 100 and 200°C, the electrochromic reactions were rich in reversibility. The coloring efficiency and response rate for the films were favorable and comparable to those for tungsten trioxide evaporated films. A cell life-test was performed on several clock-size cells by applying a 1.2-V, 1-Hz, continuous square wave. The typical amount of charge required for coloration was about 50 C / m2 and remained unchanged even after 107 coloration-bleaching cycles.
A New-Structure IR Gas Sensor
Authors: Shibata Kenichi , Yokoo Toshiaki , Takeuchi Kousuke , Tanaka Toshiharu , Kamino Maruo , Nishikawa Seiji , Nakano Shiichi , Kuwano Yukinori
Published: November 2005

We developed a new-structure IR gas sensor using a new type of pyroelectric IR detector with a solid-state chopper and an optical filter in the same package. This gas sensor enables high accuracy and high reliability due to the new structure (DEA Structure) and the new IR detector.
The accuracy of the measurement is ±0.5% in the range of a 0∼20% concentration of CO2 gas. The change of the output signal is within ±0.8% for 1500 hours. The characteristics (especially long-term operation) are superior to those of the conventional NDIR-type gas sensor.
Measurement of the Static Debye-Waller Factor of Silicon Crystals by the Pendellösung Fringe Method
Authors: Sugita Yoshimitsu , Sugiyama Hiroshi , Iida Satoshi , Kawata Hiroshi
Published: November 2005

The static Debye-Waiter factor of Czochralski-grown silicon crystals heat-treated at a high temperature has been measured by X-ray section topography. The static Debye-Waiter factor was determined through the variations in the Pendellösung fringes in a topograph. The measured static Debye-Waiter factor was proportional to the square of the scattering vector used, as expected from the theory. From an analysis of the experimental results the average size of the micro-defects formed by the heat treatment could be estimated.
Raman Cross Section of the CH4 ν1 Line in the UV Region Determined with Raman-Induced Kerr Effect Spectroscopy
Authors: Taira Yoichi , Uchikoba Fumio , Takuma Hiroshi
Published: November 2005

The absolute Raman cross section of the methane ν1 line at 266 nm has been determined to be (6.2±1.5)×10-33 m2/(mol·sr) with Raman-induced Kerr effect spectroscopy. The use of polarization detection is effective in improving the signal-to-noise ratio in a measurement using two pulsed lasers with a relatively large shot-to-shot fluctuation.
Preparation and Ion-Beam-Induced Luminescence of Thermal CVD Diamond
Authors: Taguchi Tsunemasa , Kawaguchi Yasushi , Otera Hiroshi , Hiraki Akio
Published: November 2005

Diamond particles and thin films have been grown on (111) Si crystalline substrates at about 800°C using a thermal chemical-vapour-deposition method in CH4 and H2 gas mixtures. The identification of diamond particles was achieved directly through both scanning electron microscope and X-ray diffraction measurements; the crystallite size of individual diamond particles was found to be about 1 µm in diameter. The luminescence spectra induced by an Ar-ion beam in CVD diamond have been measured at room temperature for the first time. Three radiative emission bands appeared at about 320, 400 and 450 nm, in addition to sharp atomic lines resulting from C+, N+ and H+. By comparing them with the spectrum that appears in a natural diamond single crystal, the origin of the luminescence bands is discussed.
A Simple Ultra Microbalance Utilizing Carbon Fiber as a Torsion Wire
Authors: Takeda Etsuko , Nakajima Kazutoshi , Hirohata Toru , Mizushima Yoshihiko
Published: November 2005

A simple microbalance experiment utilizing pyrolytic carbon fiber is described. It features a simple structure and high sensitivity, owing to the small fiber diameter. An application to optical power detection is indicated, and the system is expected to be capable of absolute measurements.
Microwave Sensor of Basis Weight and Moisture Content of Sheet Materials by Re-Entrant Cavity
Authors: Nakayama Shigeru
Published: November 2005

A method for performing simultaneous measurements of the basis weight (B) and the moisture weight (M) of sheet materials has been developed by using a microwave rectangular cavity. The resolution of simultaneous measurements of BM weights of paper is not good owing to the low Q-value of the cavity. The Q-value is improved by employing a re-entrant cylindrical cavity, yielding better resolution and sensitivity.
The Effect of Field Error of an Undulator Magnet on the Tune
Authors: Yonehara Hiroto , Kasuga Toshio , Kinoshita Toshio , Hasumoto Masami
Published: November 2005

The horizontal tune shift produced by the UVSOR undulator has been found to be larger than the value estimated from a quadratic field variation in the radial direction. This discrepancy is satisfactorily described in terms of a small displacement of the magnetic centers of magnet blocks in the radial direction.
Colour Switching, Dynamics and Molecular Reorientation Processes in a Very Thin Ferroelectric Liquid Crystal
Authors: Bawa S.S. , Biradar A.M. , Saxena K. , Chandra S.
Published: November 2005

Symmetric colour switching in unaligned and aligned very thin (<1 µm) samples of ferroelectric liquid crystal DOBAMBC has been observed by applying both polarities of a dc electric field. The polarization-change current developed in a very thin FLC cell has been studied by applying symmetric (-5 V–0 V–+5 V) and asymmetric [(+ or -) 10 V–0 V] triangular wave pulses. The dynamics of colour changes amongst the same colours and amongst the multicoloured 0 V favoured state and a coloured state have been studied by applying low-voltage symmetric and asymmetric square pulses. For a symmetric triangular pulse, a single peak of polarization change and for an asymmetric pulse, two peaks of polarization change near the 0 V region for molecular reorientation amongst the same coloured state have been observed. It has been established that it is essentially the presence of an additional field, called a depolarization field, which causes a single peak of polarization-change current in the case of a symmetric pulse and it is a manifestation of the combined molecular tilt from one coloured state to another without actually attaining the multicoloured state. The switching response time corresponding to a change amongst uniform identical colours has an intermediate value between the rise and decay time for the changes amongst the 0 V favoured multicoloured state and either of the coloured states.
Power Spectral Density Estimation of Light Intensity Fluctuations in Photon Counting
Authors: Musha Toshimitsu , Shimizu Keiichi
Published: November 2005

A light beam which has a constant amplitude and is incident on a photomultiplier cathode generates completely random current impulses. When the incident light intensity is fluctuating, the probability of generating current impulses is also fluctuating in time, and hence one will find current impulses obeying a compound Poisson process. The ratio of the variance to the average number of counts in successive time slots becomes larger than unity and dependent on the time slot width of the photon counting. The present paper gives a formula which reduces the shot noise level and derives the psd of the intensity fluctuations from the dependence of the variance-to-mean ratio on the time slot width. The limitation of this technique is discussed and the validity of the technique is demonstrated by computer simulation.
Sample Thickness Dependence of Minority Carrier Lifetimes Measured Using an ac Photovoltaic Method
Authors: Honma Noriaki , Munakata Chusuke
Published: November 2005

When Si wafer thickness is much smaller than the minority carrier diffusion length, the carrier lifetime, estimated by an ac photovoltaic method previously reported, has been shown to be restricted by the wafer thickness. The thickness dependence of the lifetime was measured on n-type Si wafers with thicknesses from 0.6 to 4 mm. The observed lifetimes ranged from 72.3 µs to 1.1 ms and were in good agreement with those estimated theoretically. It was demonstrated that the bulk lifetime can be obtained with less than a 10% error when the sample thickness is 3.6 times larger than the diffusion length of the minority carriers.
Bond Lengths in III–V Ternary Alloy Semiconductors
Authors: Sasaki Akio , Ichimura Masaya
Published: November 2005

An analysis was applied to 18 different III-V ternary alloy semiconductors. A thermodynamical approach was taken in order to derive relative numbers or statistics of tetrahedron cells, and then the average bond lengths were theoretically calculated. To this extent, they would give us a basic idea of the microstructure of alloy semiconductors. The theoretical results of In1-x
Ga
x
As and GaAs1-x
P
x
agree fairly well with experimental data from extended X-ray absorption fine structures.
Growth Characterization of Low-Temperature MOCVD GaN–Comparison between N2H4 and NH3–
Authors: Fujieda Shinji , Mizuta Masashi , Matsumoto Yoshishige
Published: November 2005

The reaction mechanisms of the low-temperature growth of GaN using TMG (trimethylgallium) and two different nitrogen sources, i.e., N2H4 and NH3, are presented. Quite the same temperature dependence of the growth rate for both N sources was found, suggesting that the transport and decomposition of TMG are growth-rate limiting. A different behavior between the two N sources, on the other hand, is that the flow rate of NH3 that was required to obtain a specular surface of the film was much larger than that of N2H4. This surface specularity could be well described in terms of V/III (input gas molar ratio between N source and TMG) for the case of N2H4, whereas for the NH3 case, V/H2(NH3 partial pressure) was important. A discussion of the detailed growth mechanism, especially the difference in the two N sources, is presented.
Properties of ECR Plasma in a Simple Mirror Field II–Spatial Structure of the Plasma–
Authors: Arata Yoshiaki , Miyake Shoji , Kishimoto Hiroaki
Published: November 2005

The spatial structure of an ECR plasma in a simple mirror field was experimentally studied. From axial measurements of the cold plasma parameters it was found that a plasma can be efficiently confined between the two resonance zones in the axial direction, rather than between the mirror throats, when the gas pressure is low enough to produce sufficiently hot and/or warm electrons. While measuring the radial distribution of low-energy soft X-ray emissions, it was verified that the 2nd-harmonic, as well as the fundamental, resonance zones contribute remarkably to the production of hot and/or warm electrons.
Application of Number Fluctuations to Molecular Weight Determinations
Authors: Ohbayashi Kohji , Chu Ben
Published: November 2005

We propose a new approach for determining the molecular weights of very large macromolecules in solution, or particles in suspension, by means of number fluctuations. The time correlation function and the power spectrum of scattered light from a finite number of macromolecules (or particles), N, in a small scattering volume, V
s, are derived for (a) a moving sample cell and (b) a moving slit, both with a constant linear velocity (υ). Either method improves the signal-to-noise ratio of the experiments concerning number fluctuations. Therefore, the mean number of particles (or macromolecules), , in V
s can be determined fairly rapidly.
Development of a Microwave Electro-Optic Modulator for a Laser Distance-Measuring Instrument
Authors: Nakayama Shigeru
Published: November 2005

An electro-optic modulator which operates at a frequency of around 3 GHz in the S-band microwave region was analyzed and developed for use in a laser distance-measuring instrument. A reentrant cylindrical cavity was constructed by using a KDP crystal inside the cavity. The cavity efficiency was theoretically analyzed by a finite-element method. The modulator had a laser intensity modulation index of 8% which had been obtained with a microwave input peak power of 1 W. The modulator was tested in the laboratory for distance measurements with the result that the modulator was capable of measuring a distance within an instrumental accuracy of 1 mm.
The Suitability of Ta2O5 as a Solid State Ion-Sensitive Membrane
Authors: Teravaninthorn Utis , Miyahara Yuji , Moriizumi Toyosaka
Published: November 2005

Ta2O5 films were used as ion-sensitive membranes of a solid state H+ ion sensor. The responses of the Ta2O5 films to H+ ions were characterized by utilizing 2 kinds of solid state devices: a LIS cell and an n-channel ISFET. Ta2O5 with different electrical and optical properties and crystalline structures were applied to both devices for an inspection of the relation between those properties and ion-sensitive properties. No substantial influence of the electrical properties of the films was found on the ion-sensitive properties. A crystalline transformation of the Ta2O5 film from an amorphous to a polycrystalline state by thermal annealing did not immediately effect the ion-sensitive properties however, aging tests showed it drastically reduced the film lifetime.
Thermoluminescence Dating of Fossil Calcite Shells
Authors: Ninagawa Kiyotaka
Published: November 2005

Thermoluminescence [TL] and electron spin resonance [ESR] of fossil calcite shells were investigated. The TL emission spectrum consists of a wide spectral band at 600 nm. The first- and second-glow growths observed at 240°C exhibit a common supralinear behavior, while the first- and second-ESR growths also exhibit a common saturation behavior. The total doses estimated from TL were consistent with that from ESR. Ages estimated from TL are compared with ones estimated by other methods. It is revealed that TL dating is useful for fossil calcite shells from about 5×105 years ago to recent.
Absorption Edge Studies of CuGaS2 Single Crystal
Authors: Kobayashi Satoshi , Tsuboi Nozomu , Kaneko Futao
Published: November 2005

The transmission and reflection spectra have been measured in CuGaS2 single crystals near the absorption edge in the temperature range 77–293 K. The absorption spectra for E⊥ Z calculated by assuming that the absorption band of the A-exciton is superposed on the absorption tail expressed as Urbach's rule fits the experimental spectra fairly well in that temperature range. Thus, the temperature dependence of the A-exciton energy (E
01) becomes clear. The reflectivity maximum coincides with E
01 only at low temperatures (< 100 K). Other parameters such as the damping constant, steepness factor and oscillator strength for the Γ5 exciton are also discussed.
Calculated Threshold Current Densityof Multi-Quantum-Well Wire Lasers
Authors: Ohtoshi Tsukuru , Uda Tsuyoshi , Chinone Naoki
Published: November 2005

The threshold current density J
th was studied theoretically for quantum-well wire array lasers, i.e., multi-quantum-well wire (MQWW) lasers in which the carriers are confined one-dimensionally and the wave functions in each wire are coupled together. The quantum energy levels of carriers for a two-dimensional potential distribution were calculated numerically. It was found that the J
th value for GaAs/GaAlAs MQWW lasers is about one-half that of conventional multi-quantum-well lasers and that the characteristic temperature T
0 of J
th for the former is much larger than that for the latter.
Secondary Electron Spectra Changes and Work Function Measurements for Oxygen on Ni(111)
Authors: Inoue Masahiko
Published: November 2005

The secondary electron spectra, NS(E), from Ni(111) were monitored during O2 adsorption at room temperature. At the same time AES was used to monitor θ(O2) and the oxidation process. It was observed that the variation of NS(E) was clearly divided into two stages: in the first, the onset of NS(E) shifted but the shape remained unchanged and in the second, not only the onset but the shape also changed. The second stage was found to correspond to an initial oxidation process from the chemical shift of the Ni(MVV) AES spectrum. Furthermore, the change in the onset of NS(E) was found to directly follow the work function change, even in the second stage where the shape of NS(E) varied significantly.
Magnetic Field Dependence of Critical Currents in SNS Bridges Fabricated by Direction of Sputtering Deposition and Anodie Oxidization
Authors: Nakano Hiroshi , Aomine Takafumi
Published: November 2005

We have measured the critical currents I
c in a magnetic field H applied perpendicularly on the surface of Nb–Cu–Nb bridges fabricated by a simple procedure using both directions of sputtering deposition and anodic oxdization. The I
c vs H could be explained with or without the critical current distribution; also, a demagnetizing field was taken into account when the Josephson penetration depths were longer than the bridge widths.
High-Temperature Operation of Silicon Carbide MOSFET
Authors: Kondo Yasushi , Takahashi Tetsuo , Ishii Ken'ichi , Hayashi Yutaka , Sakuma Eiichiro , Misawa Shunji , Daimon Hiroshi , Yamanaka Mitsugu , Yoshida Sadafumi
Published: November 2005

High-temperature operation up to 400°C was confirmed for a 3C-type silicon carbide (SiC) MOSFET which was fabricated in an n-type SiC layer epitaxially grown on a silicon (Si) substrate. It was also observed that the transconductance of the MOSFET increased as the ambient temperature increased.
Determination of L-Alanine Content in TGS Crystals by Optical Activity
Authors: Koralewski M. , Stankowska J. , Jasiński T.
Published: November 2005

An optical method which allows quantitative determination of L-alanine contents in L-alanine doped TGS crystals is described. L-alanine content was determined in (001) and (110) growth pyramids of LATGS crystals grown above and below T
c. Relation between E
b and alanine content in crystals established from Devonshire's theory is in reasonable agreement with the experimerttal results.
Deep Levels due to Radiation Defects in P-Type GaSb
Authors: Nakashima Kenshiro
Published: November 2005

Deep levels of defect states introduced by Co60γ-rays and electron irradiations of the GaSb p
n-junction have been investigated by capacitance transient spectroscopy. A dominant hole trap at E
v+0.27 eV has been found to be introduced irrespective of the energy of the irradiating particles. This trap center disappears at two annealing stages (around 70 and 250°C). The PL (photo-luminescence) via band-to-band transitions vanishes after irradiation, and shows a recovery in its intensity at the corresponding annealing stages (120 and 260°C) to those of the hole trap. This result suggests that the hole trap should act as an efficient non-radiative recombination center. The high-energy (10 MeV) electron irradiation effectively introduces another hole trap at E
v+0.26 eV. The origins of these hole traps are discussed on the basis of their annealing properties and the irradiating particle dependence on the defect production.
A Highly Stable Al–Si Contact to Mo-Silicided Shallow Junctions
Authors: Nagasawa Eiji , Okabayashi Hidekazu , Iida Yasuo
Published: November 2005

Highly stable (up to 550°C) contacts have been realized in an Al–2%Si contact to n
+–p and p
+–n shallow junctions (X
j∼0.16 µm) covered by a 0.1 µm thick uniform MoSi2 layer, which was formed by the ion implantation through metal ITM technique. Low contact resistance was maintained, at submicron (0.5 µm square) Al–Si/MoSi2 contacts, after 550°C sintering for 30 minutes.
An Indium-Free MBE Growth of AlGaAs/GaAs HBTs
Authors: Ito Hiroshi , Ishibashi Tadao
Published: November 2005

MBE grown AlGaAs/GaAs HBTs were fabricated using direct-radiation substrate heating. The behavior of the current gain distribution in wafers was investigated, and the variation was found to reflect the substrate temperature distributions. The decrement in the current gain is caused by an increment of generation-recombination current in the EB junction due to a low substrate temperature. Be diffusion from the base layer into the emitter layer also deteriorates the emitter injection efficiency when an undoped spacer layer inserted between the emitter and base layers is not sufficiently thick. Consequently, it is pointed out that a uniform substrate temperature distribution and a low substrate temperature with a thin undoped spacer layer are desirable. A very uniform current gain (higher than 80) was obtained for a HBT with a 4×1019/cm3 base doping at a collector current density of 1×103 A/cm2.
Measurement of the Dielectric Relaxation of Liquids by Lumped-Capacitor Time-Domain Spectroscopy
Authors: Baba Kenzo , Fujimura Tadao
Published: November 2005

A method to measure the dielectric relaxation of liquids by lumped-capacitor time-domain spectroscopy is described. The principle of this method is the same as that for solids which was reported by us. The relaxations of a number of alkyl alcohols were measured at 25.0°C. The results agreed well with earlier work.
Fluctuation of Power Output Due to Instability in Closed Cycle MHD Power Generation
Authors: Shimizu Eliko , Yoshikawa Yukio , Kabashima Shigeharu
Published: November 2005

The fluctuating output power has been measured for a disk-type MHD generator with a FUJI-1 closed-cycle MHD power generation facility. The fluctuation shows random properties which are associated with the ionization instability of the plasma in the generator. The random properties of the output power can be explained by a Poisson process. The experimental results have been ensured by a numerical simulation based on two temperature model equations which are conventionally used for analyses of the nonequilibrium MHD power generation. Calculations show the coexistence of a two state plasma in a disk-type generator associated with an ionization instability.
Deep Levels in n-Type Undoped and Te-doped InSb Crystals
Authors: Tokumaru Yozo , Okushi Hideyo , Fujisada Hiroyuki
Published: November 2005

Deep levels in InSb crystals used for photodiodes have been investigated. An electron trap was found at 0.10 and 0.12 eV below the conduction band in n-type undoped and Te-doped InSb, respectively. A hole trap was observed in both specimens and its level in a Te-doped specimen was estimated to be 0.032 eV above the valence band. The distribution profile and electron capture cross section of the electron traps were also measured.
Fabrication of LiTaO3 Optical Waveguide by H+ Exchange Method
Authors: Tada Kunio , Murai Toru , Nakabayashi Takashi , Iwashima Toru , Ishlkawa Takuya
Published: November 2005

LiTaO3 is a promising material for optical devices because of its resistance against optical damage. In this work we have successfully fabricated waveguides on z-cut LiTaO3 wafers by the proton exchange method and have propagated several modes in them. Both the increment of the refractive index and the `exchange coefficient' were determined optically. The effect of an annealing process was also studied. The propagation loss was measured to be 1 dB/cm.
Absolute Detection Efficiency of a Microchannel-Plate Detector for Ions and Neutrals
Authors: Tobita Kenji , Takeuchi Hiroshi , Kimura Hironobu , Kusama Yoshinori , Nemoto Masahiro
Published: November 2005

The absolute efficiencies of a microchannel-plate detector for He+ and He0 were measured in the energy range of 1 to 10 keV. There was no difference between He+ and He0 incidences regarding efficiency, and the efficiency was constant in the above energy range. This value indicates that almost all the particles hitting the entrance wall of the MCP pores were detected.
DLTS Study of Heat Treatments on n-CdTe Crystals
Authors: Tomitori Masahiko , Kuriki Makoto , Hayakawa Sohachiro
Published: November 2005

DLTS measurements were carried out on Schottky barriers formed on the surfaces ofn-CdTe:In crystals heated in argon gas. Four electron trap levels were detected. The carrier concentration near the surface decreased to less than a tenth as a result of heat treatments at 350 or 400°C for 1 hour. A sample heated at 400°C showed a steep decrease in the carrier concentration near the surface. The concentration of an electron trap level (EC-ET=0.34 eV) was reduced by heat treatments. Heat treatments at temperatures higher than 350°C for 1 hour seemed to induce some defects related to cadmium vacancies or tellurium interstitials, which compensate donors and reduce the concentration of the trap level near the surfaces of CdTe.
Behavior of Liquid Fuse in a Non-Destructive Opening Switch
Authors: Ikuta Kazunari
Published: November 2005

This paper proposes the use of an exploding liquid fuse in a liquid insulator, e.g. water, as a possible non-destructive opening switch. The opening time was culculated analytically with a simple model for the explosion of the liquid fuse. This analytical model was also checked by a numerical computation.
H-Mode Outside Divertor Free from Peripheral Disruption in Doublet III
Authors: Kameari Akihisa , Konoshima Shigeru , Abe Mitsushi , Itoh Kimitaka , Kitsunezaki Akio , Nagami Masayuki , Shimada Michiya , Sengoku Seio , Washizu Masao
Published: November 2005

The heating efficiency and the peripheral disruption of three distinctively different divertor configurtions were studied in Doublet III at a plasma current of 600 kA up to the neutral injection power of 7.5 MW. An outside divertor configuration with a good energy confinement (H-mode), which has a null point at the outside in the major radius and of which separatrix field lines divert to the outside wall, was observed. The discharges of the outside divertor configuration were free from the peripheral disruption characterized by H
α/D
α bursts and the stored energy was nearly proportional to the injection power up to 7.5 MW of NBI.
High Field Torque Magnetometer for Superconducting Magnets
Authors: Otani Yoshichika , Miyajima Hideki , Chikazumi Sōshin
Published: November 2005

A torque magnetometr utilizing a pulley system was designed for use in a superconducting magnet. The sample is rotated by a synchronous motor with the rotational axis perpendicular to the direction of the applied magnetic field. The magnetic torque from 102 to 106 dyn cm can be measured with an accuracy of 1% in a high magnetic field. This type of torque magnetometer is convenient for measuring large magnetic anisotropy. The temperature dependence of the anisotropy constants for Pr2Fe14B was measured in magnetic fields up to 100 kOe and over the temperature range from 4.2 to 300 K.
Sputtering System for the Preparation of Compositionally Modulated Films
Authors: Togami Yuji , Morishita Tadataka , Tsushima Kuniro
Published: November 2005

A novel sputtering system that was specially designed for synthesizing compositionally modulated films (CMF's) has been produced. In this system, substrates remain above one of two targets during deposition; the substrate positions and deposition periods are computer controlled. Periodic structures in Fe/SiO2 CMF's prepared by the system have been investigated by X-ray diffraction and were found to be well-defined.