bluuebunny/crossref_metadata_2025 huggingface dataset:
A Defect Control Technique for the Intrinsic Gettering in Silicon Device Processing
Authors: Kishino Seigō , Aoshima Takaaki , Yoshinaka Akira , Shimizu Hirofumi , Ono Minoru
Published: November 2005

A short period low-temperature-annealing procedure is proposed for the two step annealing process to make effective intrinsic gettering in silicon device processing. A continuous raising of annealing temperature at a constant rate during the low temperature annealing step increases the density of bulk microdefects which are able to grow further in the subsequent high temperature device processing step. The temperature raising rate is limited so that the expanding speed of the critical size of microdefects at the annealing temperature is lower than the growth rate of microdefects. The optimum defect density is discussed from the standpoint of wafer warpage and gettering ability.
Simultaneous CW Operation of 5-Wavelength Integrated GaInAsP/InP DFB Laser Array with 50 Å Lasing Wavelength Separation
Authors: Okuda Hajime , Hirayama Yuzo , Furuyama Hideto , Uematsu Yutaka
Published: November 2005

The simultaneous CW operation of a 5-wavelength integrated GaInAsP/InP DFB laser array has been realized. The average lasing wavelength separation was 49 Å, which was in very good agreement with the designed value. Threshold currents were 57 to 75 mA and differential quantum efficiencies were 11 to 21%. A simultaneous CW operation was obtained at up to 40°C with each stable single longitudinal mode. It was found that the threshold current was almost independent of wavelength within a range of 500 Å on the long wavelength side of the spontaneous emission peak and could be reduced to as little as 20 mA by fabricating deep, uniform gratings and by increasing the crystal homogeneity of the wafer.
Growth of Hydrogenated Amorphous Silicon Films by ArF Excimer Laser Photodissociation of Disilane
Authors: Yoshikawa Akihiko , Yamaga Shigeki
Published: November 2005

Hydrogenated amorphous silicon films have been grown on glass substrates by photodissociation of disilane using a pulsed ArF excimer laser foe the first time. Electrical and optical properties of the films have been examined. It was found that the magnitude of the gap energy of laser CVD films is rather large as compared to that of films obtained by a conventional plasma CVD. Preliminary examinations to control the conductivity by impurity doping have also been performed.
Fabrication of GaAs MESFET Ring Oscillator on MOCVD Grown GaAs/Si(100) Substrate
Authors: Nonaka Toshio , Akiyama Masahiro , Kawarada Yoshihiro , Kaminishi Katsuzo
Published: November 2005

GaAs MESFET ring oscillators were successfully fabricated on silicon substrate. GaAs epitaxial layers were grown directly by MOCVD on Si(100) substrate. A typical transconductance of 200 mS/mm was observed for the FET of 1.0 µm × 10 µm gate. A minimum propagation delay time of 51 ps/gate at a power dissipation of 1.1 mW/gate was observed for an E/D gate ring oscillator with gate length of 1.0 µm.
Characterization of LP-MOCVD Grown (Al, Ga)As/GaAs Heterostructures by Photoluminescence: Single Heterojunction and Inadvertent Quantum Wells
Authors: Zemon S. , Black J. , Norris P. , Lee J. , Lambert G.
Published: November 2005

Photoluminescence (PL) was used to detect rapid alloy compositional fluctuations which were found in (Al, Ga)As/GaAs heterostructures grown by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). PL data are employed to estimate the thickness and aluminum composition of the resulting inadvertent quantum well. A way to eliminate these artifacts was found. Using the improved growth procedures, modulation-doped heterostructures showing two-dimensional electron-gas behavior were then achieved.
Formation of Drawing-Induced E' Centers in Silica Optical Fibers
Authors: Hibino Yoshinori , Hanafusa Hiroaki , Sakaguchi Shigeki
Published: November 2005

Using an electron spin resonance technique, E' centers have been observed in pure silica optical fibers fabricated under various drawing conditions. The E'-center concentration increases with increasing furnace temperature and drawing velocity. The influences of the temperature and velocity have been studied by considering the diameter and temperature distributions of a preform in the drawing furnace. The analysis indicates that the E' centers are frozen in the optical fibers by a thermal activation process in the furnace. The activation energy for the creation of the E' centers is determined as 3.5±0.5 eV, and the effective recombination density for the decay of the E' center as 6.2×10-13. Furthermore, the fictive temperature of the optical fibers is estimated to be more than 2100 K from the E'-center concentration.
Annealing Studies on Hydrogenated Amorphous Silicon-Tin Films
Authors: Morimoto Akiharu , Kataoka Toyotaka , Shimizu Tatsuo
Published: November 2005

Hydrogenated amorphous Si-Sn (a-Si1-x
Sn
x
:H) films were prepared by radio-frequency sputtering of the planarmagnetron type, and optical absorption, infrared absorption, Raman scattering, electron spin resonance and conductivity measurements were carried out on these films. Annealing experiments revealed that the a-Si1-x
Sn
x
:H films had a low crystallization temperature, a low evolution temperature of H atoms and a low degradation temperature for the photoconductivity, compared with a-Si:H films. The incorporation of N into these films was found to improve the thermat stability without a large increase in the optical gap, although it decreased the photoconductivity.
Two-Frequency Moiré Topography
Authors: Ibrahim M. Djamil , Takasaki Hiroshi
Published: November 2005

Moiré topography visualizes the contour lines of an object, but it requires the absolute order of the fringe to be analyzed, and cannot distinguish the concavity and convexity of a portion of an object showing closed moiré fringes. The two-frequency moiré topography technique proposed here readily gives the absolute order of a fringe, and gives oblique intersection lines which help in identifying the concavity and convexity of local curvature. The technique is especially suitable for collecting data on unknown shapes such as a deformed human body.
Maximum Entropy Spectral Analysis of Time-Series Data from Combustion MHD Plasma
Authors: Seidou Tadashi , Aoki Yoshiaki , Ohtomo Norio
Published: November 2005

The maximum entropy method (MEM) was applied to the time-series intensity data of the total light radiation from a combustion MHD plasma, and power spectral densities with many characteristic peaks were obtained in the range of a few kHz to ca. 30 kHz. Minimization of FPE, AIC, and CAT was employed to determine the optimum prediction-error filter order required for the MEM spectral analysis. Using the plasma flow velocity of 250 m/s obtained from cross-correlation function analysis, the frequency spectrum of the temperature was transformed to the wave-number-dependent power spectral density, in which a k
-5/3-dependence was found in the k-range corresponding to the inertial subrange.
Observation of Magnetic Domain Walls in Co and Co-Fe by Differential-Phase-Contrast STEM
Authors: Sekiguchi Takashi , Watanabe Denjiro , Tsuno Katsushige
Published: November 2005

Using a conventional 200 kV transmission electron microscope equipped with a double-gap magnetic-field-free objective lens, quadrant detector and scanning attachment, magnetic domains in Co and 1.2 at.% Fe-Co single crystals have been observed in the differential-phase-contrast STEM mode. The advantages of the method over the Fresnel method of Lorentz microscopy are demonstrated, e.g., in the measurement of wall width and in the understanding of the true features of complicated domain structures: in 290 nm-thick hcp Co, the wall width is determined as 34±5 nm, and in Co-Fe alloy, the true features of the wall structures at the interface between the two phases, hcp and dhcp, coexisting in a fine scale, are revealed.
Electrical and Structural Properties of Amorphous In-Se Films Prepared by Flash Evaporation
Authors: Watanabe Ichiro , Yamamoto Teiji
Published: November 2005

Electrical conduction in amorphous In
x
Se100-x
films is actually n-type, although some workers have considered it to be p-type, since p-type conduction is observed in the partially-crystallized films. A fairly large upward-Fermi-level-shift appears, in particular, in films with composition near x=40. Raman measurements show that In and Se are incorporated in the network in such a way that their surroundings are the same as those in α-In2Se3 crystal in the composition range x= 0 ∼28, in γ-In2Se3 crystal at x=40 and in InSe crystal at x=50. The coordination number of In is likely to be four except at the composition near x=40, where five-fold coordinated In also exists, while the coordination number of Se is mainly three.
RHEED Study of Surface Reconstruction at Clean Ge(110) Surface
Authors: Noro Hisato , Ichikawa Toshihiro
Published: November 2005

Surface reconstruction at a clean Ge(110) surface is reported to show uncommon features such as the reappearance of the low-temperature phase at higher temperature and temperature-dependent faceting. In order to investigate the features in detail, in-situ RHEED observations of cleaned and annealed Ge(110) surfaces were undertaken. The reap-pearance phenomenon was confirmed in the present RHEED observation, but no faceting occurred.
Measurement of the Out-Diffusion Profile of Oxygen in Silicon
Authors: Sugita Yoshimitsu , Kawata Hiroshi , Nakamichi Shuhei , Okabe Toshio , Watanabe Toshihide , Yoshikawa Shigeo , Itoh Yoshiko , Nozaki Tadashi
Published: November 2005

The concentration profile of out-diffused oxygen in Czochralski silicon crystals has been measured in identical specimens by X-ray lattice parameter measurement, charged-particle activation analysis, and spreading-resistance measurement after thermal donor formation. The experimental profiles obtained by the X-ray method and charged-particle activation analysis were consistent, but the spreading-resistance method yielded less reliable results. The surface concentration of oxygen is discussed on the basis of Henry's law.
Calculated Electron Mobility of Two-Dimensional Electrons in AlInAs/InGaAs and InP/InGaAs Single Heterostructures
Authors: Takeda Yoshikazu , Sasaki Akio
Published: November 2005

The self-consistent variational technique is used to calculate the mobility of two-dimensional electrons at the hetero-in-terfaces in AlInAs/InGaAs and InP/InGaAs single heterostructures. The sheet electron concentration dependence of the total mobility and each-scattering-limited mobility are shown. The predominance of the alloy-scattering-limited mobility is demonstrated. Model calculation of the two-dimensional electron mobility in an alloy-scattering-free InAs/GaAs monolayer superlattice with AlInAs as the barrier is also presented.
Josephson Junctions with Short Semiconductor Links Separated by Osidized Layer
Authors: Okabe Yoichi , Takatsu Motomu
Published: November 2005

Josephson junctions with short semiconductor links have been fabricated by a thermal oxidation process. The length and width of typical links are 20 nm and 2 µm, respectively. The two electrodes of the junction are separated by a thin oxide layer and are electrically coupled through an underlying degenerate semiconductor layer. With this structure, it should be possible in principle to fabricate links of length in the 10 nm range with relatively high reproducibility. The I-V characteristics were measured at 4.2 K, from which the I
c
R
n products of 0.1–1.0 mV were obtained. From the rf excitation measurements, more than 33 microwave induced steps were observed at a frequency of 9.18 GHz.
Zone-Folding Effects on Phonons in GaAs-AlAs Superlattices
Authors: Nakayama Masaaki , Kubota Kanji , Kanata Takashi , Kato Hiromu , Chika Shigeaki , Sano Naokatsu
Published: November 2005

Raman spectroscopy has been used to study the zone-folding effects on both longitudinal acoustic (LA) and longitudinal optic (LO) phonons in (GaAs)
n
-(AlAs)
n
superlattices with integral n (2 ∼12) grown by molecular-beam epitaxy. All the observed frequencies of the zone-foled LA phonon modes up to the sixth order agree well with those calculated using the elastic model, while the observed frequencies of the zeroth- and first-order zone-folded LO phonon modes agree with those calculated using the linear-chain model. However, since long-range interactions are neglected in the linear-chain model, this model is not a good approximation for the higher-order modes. In contrast to the LA phonon modes, all the GaAs- and AlAs-like LO phonon modes are confined in the GaAs and AlAs layers, respectively.
Analysis of Discharge Properties in CCl2F2by the Boltzmann Equation Method
Authors: Okabe Shigemitsu , Kouno Teruya
Published: November 2005

In order to make detailed analysis by the Boltzmann equation possible, a set of electron collision cross-sections for CCl2F2, an important material in various fields, is determined for the first time. In spite of the lack of available cross-section data, Boltzmann equation analysis using the set of values determined here gives calculated values which agree well with measurements of the swarm parameters of CCl2F2, indicating the validity of the cross-section set and the method of analysis. In addition, the accuracy of the set of values was checked by test calculations, and the Boltzmann equation method was then applied to CCl2F2+N2gas mixtures, giving results which explain the flashover properties of the mixtures very well.
Direct Measurement of the Energy Distribution of an Intense Relativistic Electron Beam
Authors: Kawai Masayuki , Kawamura Yoshiyuki , Toyoda Koichi
Published: November 2005

The energy distribution of an intense relativistic electron beam (IREB) having a voltage of ≈0.75 MV, a current of 23 kA, and a duration of 30 ns was investigated using a magnetic-deflection-type energy analyzer. The IREB was found to have an exponential distribution with a sharp discontinuity at the maximum energy and a gradual decay toward lower energy. The energy spread was 6% of the maximum energy.
Properties of Hydrogenated Amorphous Si-N Prepared by Various Methods
Authors: Morimoto Akiharu , Tsujimura Yoshinori , Kumeda Minoru , Shimizu Tatsuo
Published: November 2005

The results of optical absorption, infrared absorption, electron spin resonance and photoluminescence measurements are presented for hydrogenated amorphous Si-N films prepared by three different methods; magnetron sputtering of an Si target in an Ar+N2+H2 gas mixture, glow-discharge decomposition of SiH4+N2, and glow-discharge decomposition of SiH4+NH3. The improvement in the properties of films prepared by the third method, e.g., the sharp band tail and low dangling-bond density, is explained mainly in terms of the structual softening due to the existence of N-H bonds. The fatigue of the photoluminescence due to illumination is found to be more prominent and the recovery due to annealing less prominent in N-incorporated film than in a-Si:H.
Preparation Capacity of Reactive Evaporation Method for Amorphous Silicon
Authors: Shindo Masanori , Sato Shigeru , Myokan Isao , Mano Shigeru , Shibata Takuji
Published: November 2005

Doped a-Si:H films, and nondoped and doped a-Si:N:H films were prepared by the electron-beam deposition of silicon, hydrogenation being achieved by supplying hydrogen ions to the film surface during deposition. The photo- and dark-conductivities showed characteristics similar to those of films prepared by SiH4 glow discharge and CVD. Boron, in the form B2H6, and Al were used as p-type dopants, while Sb was used as an n-type dopant.
Phase Transition of Lipid Multilameller Aqueous Suspension under High Pressure. II. Structural Analyses of Lipid Bimembrane under High Pressure by X-Ray Studies
Authors: Utoh Shigenori , Takemura Tetuo
Published: November 2005

The structural changes accompanying the respective transitions of hydrated synthetic dipalmitoyl phosphatidylcholine under high pressure have been studied using WAXS and SAXS methods. The following experimental facts were observed: Under high pressure above about 2.5 kbar, the unknown phase below the sub-transition temperature exhibits the complete orthorhombic structure in hydrocarbon-chain packing; however, below about 2.5 kbar, the quasi-orthorhombic and orthorhombic structures coexist when the sample has an annealing history. At this sub-transition under high-pressure transformation from the unknown phase to the L
β' phase, a melting-like-process concerning the movement of head groups of the lipid takes place. The difference between the conformational changes above and below about 2.5 kbar at the pre-transition comes from the existence of the tricritical point at approx. 2.5 kbar and 78°C in the pre-transition line.
Monte Carlo Simulation Approach to Sputtering in Multi-Component Targets
Authors: Kang Hee Jae , Kawatoh Eizoh , Shimizu Ryuichi
Published: November 2005

A Monte Carlo approach based on the use of an analytical approximation formula for the Ziegler-Biersack-Littmark potential to simulate the sputtering processes in multi-component targets is presented. The approach was verified by applying it to TiC and AuCu targets under Ar+-ion bombardment to obtain the escape depth-, energy- and angular-distributions of component atoms sputtered from the targets. The escape depth distribution suggests that most of the sputtered atoms originate from the first and second layers of the surface. The energy- and angular-distributions of component atoms sputtered from TiC and AuCu targets are also presented.
Anger Electron Emission under Ion-Beam Shadowing Conditions
Authors: Kudo Hiroshi , Murakami Kouichi , Takita Kôki , Masuda Kohzoh , Seki Seiji , Shima Kunihiro , Itoh Hisayoshi , Ippōshi Takashi
Published: November 2005

By analyzing the electrons emitted at 180° with respect to the ion-beam direction, we have carried out an improved measurement of the energy-degradation spectra of Si K-shell Auger electrons induced by 18- and 24-MeV He++. The ions were incident on a silicon single crystal under <110 > shadowing and random conditions. From the analysis of the degradation-spectrum width for the shadowing conditions, the stopping power for 1.6-keV electrons in a silicon crystal was determined as 1.50±0.08 eV/Å, close to the theoretical value of 1.6 eV/Å obtained by Tung et al. The present results are almost consistent with a previous work by Kudo et al. carried out under different experimental conditions.
Photoacoustic Signal from Subsurface Defects in Ceramics
Authors: Tomeno Izumi , Ohzu Hideyuki
Published: November 2005

The laser scanning photoacoustic (PA) technique was used to detect subsurface slots in Si3N4, SiC and AlN ceramics. The PA signal amplitude peak width across the slot decreased with increasing chopping frequency, up to 480 Hz. At low frequencies, the peak width for SiC and AlN was considerably larger than that for Si3N4. This is ascribed to the difference in thermal diffusivity among these ceramics. The amplitude peak height vs subsurface slot depth relationships for Si3N4 are in good agreement with the calculation based on the Rosencwaig-Gersho theory. However, the relation-ships for SiC and AlN disagree with the calculation. This suggests that at low frequencies the PA signal on the slot is affected by the thermal diffusion outside the slot.
Raman Scattering Study of Tehrmal SiO2 Layers Grown on Silicon
Authors: Kodama Takeshi , Iwaoka Teiji , Osaka Yukio
Published: November 2005

Raman scattering in thermal SiO2 layers grown on silicon under various conditions was studied. An experimental arrangement similar to that used for interference-enhanced Raman scattering was employed to increase the sensitivity of the Raman scattering. The results show that thermal SiO2 with a thinner oxide or grown at a lower temperature has a larger density of defects, and that the degree of structural disorder of thermal SiO2 is larger in thinner oxides.
Infrared Reflectivity Spectrum and Lattice Vibration of Spinel-Type Compound HgIn2S4
Authors: Wakaki Moriaki
Published: November 2005

Indium thiospinel compound with normal spinel structure HgIn2S4 single crystal was synthesized by the Bridgman method, and far-infrared reflection and transmission spectra were measured in the wavelength region from 20 to 1000 cm-1. The dispersion parameters are calculated by dispersion analysis using classical oscillators. The strength of the four kinds of short-range force constant is calculated using the dynamical matrices proposed by Bruesch et al., and the effective charges for each ion are obtained under several assumptions.
K-Edge XANES of GaP, InP and GaSb
Authors: Oizumi Hiroaki , Iizuka Junichi , Oyanagi Hiroyuki , Fujikawa Takashi , Ohta Toshiaki , Usami Seiji
Published: November 2005

X-ray-absorption near-edge structure (XANES) spectra for crystalline GaP, InP and GaSb were measured for each Ga and P K-edge region. Full multiple scattering calculations are performed. The information on the charge distribution around the X-ray-absorbing atom can be obtained by comparing the experimental XANES spectra with the full multiple scattering calculations. The effective cation charge distributions are predicted to be q= ∼0.33 for GaP, q=0.42 ∼0.5 for InP and q \lesssim0.26 for GaSb.
Material Dependence of Strain Distributions of Surface Acoustic Waves in Multilayered Thin-Film Acousto-Optic Devices
Authors: Goto Nobuo , Miyazaki Yasumitsu , Akao Yasuo
Published: November 2005

The acoustic strain distributions in thin acousto-optic waveguides consisting of two-layered thin amorphous films on a Y-cut, X-propagation LiNbO3 substrate are studied. The theoretical relation between the elastic properties and the strain distributions in layered thin films is discussed. The strains contributing to acousto-optic interactions in the film increase as the Poisson ratio of the film material decreases. The strain amplitude in each of the layered thin films can be controlled over a wide range by suitable selection of choosing the film materials. The results give important information on improving the mode-conversion efficiency in thin-film acousto-optic devices and for designing various waveguide-type devices using acousto-optic interactions. Further, method of evaluating the elastic properties of amorphous films is discussed.
Ion-Species Dependence of Interdiffusion in Ion-Implanted GaAs-AlAs Superlattices
Authors: Hirayama Yoshiro , Suzuki Yoshifumi , Okamoto Hiroshi
Published: November 2005

The interdiffusion coefficients of Ga and Al were measured for GaAs-AlAs superlattices ion-implanted with Be, B, F, Si, Ar and As. The degree of interdiffusion enhancement was in the order Si>F>As>B and no interdiffusion enhancement effects were observed for Be and Ar. Except for Be, impurities with large diffusion coefficients have a tendency to enhance the impurity-induced compositional disordering.
Quantitative Analysis of In Density in Semi-Insulating GaAs by Photoluminescence
Authors: Kitahara Kuninori , Kodama Kunihiko , Ozeki Masashi
Published: November 2005

Photoluminescence (PL) measurements at 4.2 K were performed on In-doped semi-insulating GaAs (In
x
Ga1-x
As) grown as a nearly dislocation-free substrate for GaAs large-scale integrated circuits. The In composition x of the sample wafers was calibrated by inductively-coupled-plasma emission spectrometry before the PL measurement. A small variation of In composition in the region 0 ≤x ≤0.0139 was detected by the peak-energy shift of exciton-recombination emissions Δh ν (eV). The value of x could be estimated from Δh ν using the equation x=- Δh ν/1.505 without destruction of the sample wafers. It was found that the emission of neutral-acceptor-bounded-exciton recombination observed in all samples was useful for the measurement of the x value.
Correlation between Time-Resolved Soft X-Ray Images and Interferometric Results in a Plasma Focus
Authors: Hirano Katsumi , Yamamoto Toshikazu , Shimoda Katsuji , Tagaya Yutaka
Published: November 2005

A time-resolved soft X-ray pinhole camera equipped with a microchannel plate as an image sensor was successfully developed for observation of a rapidly-changing plasma produced by a plasma focus device. Simultaneous observation with the pinhole camera and a Mach-Zehnder interferometer was carried out. This observation showed that the soft X-rays are emitted from the collapse phase to the disruption of the plasma focus. A high-intensity spot of the soft X-rays is recognized just before the disruption of the plasma column. In spite of the higher resistivity of the plasma column, it is found that the soft X-ray emission is not intense after the disruption. This comes from the rapid decrease of the electron density in this phase.
Cross Check of Electron Density Distribution by Moiré-Schlieren Technique and Mach-Zehnder Interferometry
Authors: Hirano Katsumi , Matsumoto Chiaki , Shimoda Katsuji , Yamamoto Toshikazu
Published: November 2005

Simultaneous measurements of the electron density in a plasma focus by a Moiré-Schlieren technique and Mach-Zehnder interferometry were carried out to investigate the unavoidable error in the interferometry generated by refraction of the probe beam by the density gradient. The refraction angle was measured precisely by the Moiré-Schlieren technique, and the spatial distribution of the electron density calculated from the refraction angle agreed well with that obtained by Mach-Zehnder interferometry. The error produced by the refraction is found to be negligible if an N2-laser is employed as the light source for the plasma focus.
A Cylindrical Multi-Layer Drift Chamber for a Low-Energy p̄p Experiment
Authors: Kageyama Tatsuya , Nakamura Kenzo , Sai Fuminori , Sakamoto Shin'ichi , Sato Shinji , Takahashi Tadayuki , Tanimori Tohru
Published: November 2005

A five-layer cylindrical drift chamber was constructed for a low-energy p̄p experiment. The chamber was located inside a dipole magnet with an applied field of 2.5 kG, and a liquid-hydrogen target was embedded at the center of the chamber. Since the beam traversed the chamber, care was taken in the design of the drift cells. A spatial resolution of about 200 µm was obtained in the presence of magnetic fields.
A Static Magnetic Refrigerator for Superfluid Helium with New Heat Switches and a Superconducting Pulse Coil
Authors: Hakuraku Yoshinori , Ogata Hisanao
Published: November 2005

A new magnetic refrigerator is proposed which can produce and preserve superfluid helium with high reliability and efficiency. This paper describes the design of the refrigerator and presents the results of experimental tests using a model refrigerator. The refrigerator is designed to give a Carnot cycle in a temperature range of 1.8–4.2 K. Gadolinium gallium garnet (GGG) is employed as the working substance, and new heat switches which have no moving parts and make use of differences in the heat transfer rates in the various heat transfer modes of a fluid are used. The working substance is magnetized and demagnetized by means of a superconducting pulse coil. A useful cooling power of about 0.6 W was obtained at 1.80 K. The calculated and experimental results verify that the magnetic refrigerator can, in principle, stably and continuously produce and maintain superfluid helium.
Conceptual Design of a New Magnetic Refrigerator Operating between 4 K and 20 K
Authors: Hakuraku Yoshinori , Ogata Hisanao
Published: November 2005

A thermodynamic cycle analysis has been performed on a new magnetic refringeration system for liquid helium. This system features the use of two heat switches and a small helium-gas refrigerator to establish a high-temperature heat sink. As a result of cycle analysis, it is clarified that cooling power of 1 W at 4.5 K can be attained.
Structure and Chemical Effects on the K-Absorption Edge of Cobalt in Some Mixed Ligand Cobalt Complexes
Authors: Khadikar Padmaker V. , Anikhindi Ramesh G.
Published: November 2005

The extended fine structure of the cobalt K-absorption discontinuity in some mixed ligand cobalt complexes is interpreted with the recent theory proposed by Lytle, Sayers and Stern (1975). Bonding parameters are compared with those obtained from optical spectra.
A New Interferometric Alignment Technique with Holographic Configuration
Authors: Nomura Noboru , Matsumura Takayoshi , Yonezawa Taketoshi , Kugimiya Koichi
Published: November 2005

A new interferometric alignment technique using a holographic configuration with a precision of the order of tens of nm has been developed for registering a grating on a substrate to an interference fringe of two conjugate beams in a space. The alignment between a grating and a fringe was determined from the moiré image generated by the beams diffracted from the grating, and a theoretical analysis was performed to calculate the intensity of the moiré image. The experimental results were in good agreement with the calculations. The application of the method to a wafer stepper with submicron resolution is proposed.
Excimer-Laser-Induced Chemical Vapor Deposition of Hydrogenated Amorphous Silicon
Authors: Yamada Akira , Konagai Makoto , Takahashi Kiyoshi
Published: November 2005

Hydrogenated amorphous silicon (a-Si:H) films were rapidly deposited (55 Å/s) by the laser-induced chemical vapor deposition (LCVD) technique. An ultraviolet pulsed ArF excimer laser was used for excitation of disilane gas. The films were characterized by photo and dark conductivity, optical bandgap, and infrared (IR) absorption spectroscopy measurements. The IR spectra showed that the films prepared at a lower substrate temperature had incorporated more hydrogen. A photo-conductivity of 2×10-4 Scm-1, a dark conductivity of 2×10-9 Scm-1, and an optical bandgap of 1.75 eV were obtained at a deposition rate of 1 Å/s. Spontaneous emission from silicon atoms, hydrogen atoms, and silicon-monohydride molecules, was observed by optical emission spectroscopy (OES).
Effects of Thermal History on Microdefect Formation in Czochralski Silicon Crystals
Authors: Shimanuki Yasushi , Furuya Hisashi , Suzuki Isamu , Murai Koji
Published: November 2005

The mechanism of formation of microdefects in Czochralski silicon crystals is investigated, with particular attention to the effects of the thermal history in the growth process on the nucleation and growth of oxygen precipitates. The density and size of the nuclei of oxygen precipitates in the asgrown state of a crystal subjected to a special thermal history are analyzed in detail. The behaviors of the nuclei at various temperature ranges of the thermal history are then discussed on the basis of these analyses.
Observation of Shock-Induced Phases of Nb2O5 Single Crystal under High-Resolution Electron Microscopy
Authors: Kikuchi Masae , Kusaba Keiji , Bannai Eisuke , Fukuoka Kiyoto , Syono Yasuhiko , Hiraga Kenji
Published: November 2005

Shock-loading experiments on Nb2O5 single crystals were carried out up to 54 GPa by the gun method. The shock-loaded materials are recovered by using both closed and open recovery fixtures and were examined by powder X-ray diffraction analysis and high-resolution electron microscopy. Complete conversion to T-Nb2O5 of µm size, denser by 12% than H-Nb2O5, was found in the pressure range from 20–40 GPa. When single-crystal H-Nb2O5 was shocked perpendicular to the b-axis using the open-system recovery fixture, an unidentified phase referred to as the X-phase, besides T-Nb2O5 and shock-reduced Nb
x
O2 with the rutile structure, was observed. The high-resolution image of the X-phase is interpreted as two-dimensionally disordered H-Nb2O5. The X-phase is probably formed in the rapid decompression process from the shock-induced high-pressure phase.
Harmonic Mixing with SIS Tunnel Junctions in the Millimeter and Submillimeter Regions
Authors: Kobayashi Masayoshi , Ohara Shinji , Katsuno Akira , Sakai Kiyomi , Hayashi Yoshikazu
Published: November 2005

The characteristics of SIS (Superconductor-Insulator-Superconductor) harmonic mixing were studied in the millimeter and submillimeter regions. IF (Intermediate Frequency) signals originating from the Josephson effect and the photon-assisted tunneling were observed. Each property was investigated by applying a magnetic field. Compared with mixing based on photon-assisted tunneling, mixing by the Josephson effect required low LO (Local Oscillator) power and gave rise to a smaller conversion loss, but more noise.
Constant-Voltage Steps in the V-I Curve of a J-J Loop
Authors: Takeuchi Sumitaka , Narita Hidemi , Kobayashi Tadayuki , Hamasaki Katsuyoshi , Yoshikawa Shokichiro , Yamashita Tsutomu
Published: November 2005

Both resonant and microwave-induced steps in the V-I characteristics of four-Josephson-junction loop with a small junction-parameter spread have been investigated. An rf current was superimposed onto a dc current and the radio frequency was tuned to the resonance frequency of the loop. In the high-Q region, the rf-power dependence of the step amplitude was similar to that of a single junction. However, we obtained V-I characteristics which indicated that the behavior of the junction in the loop was coherent in the low-Q region.
Magnetization Distribution of Film Edge Region Under a Spatially-Decreasing External Filed
Authors: Hirono Shigeru , Nonaka Koutaro , Hatakeyama Iwao
Published: November 2005

The magnetization distribution of a magnetic curling state in a film edge region is analyzed under a spatially-decreasing field such as an external field from magnetically-recorded bits. A newly developed curling-state analysis is presented which takes the total magnetostatic energy due to surface and volume charges into consideration. The analysis gives the magnetization distribution of the curling state in the film edge region under the spatially-decreasing field. It further enables the energy factors to be evaluated quantitatively to determine the magnetization distribution of the curling state. Finally, it also demonstrates quantitatively that the magnetostatic energy cannot be neglected in determining the magnetization distribution of the film, and the energy suppresses magnetic induction for a high-magnetization film under the spatially-decreasing field.
Analysis of Quasi-Periodic Undulationon Pulsed CO2 Laser
Authors: Shimizu Fumiko O.
Published: November 2005

Characteristics of the undulation superposed on the transient laser output in the afterglow region have been exactly analyzed by numerical integration of the nonlinear rate equations. Observed results are very well reproduced by the calculation. It is also confirmed that the present system satisfy the condition for occurence of the relaxation oscillation. Laser parameters such as the population inversion, the photon density as well as the relaxation parameters are also determined simultaneously. The method of present analysis may be generally applicable for determination of various dynamical constants associated with laser processes.
Selective Epitaxial Growth of GaAs by Metalorganic Chemical Vapor Deposition
Authors: Yamaguchi Ko-ichi , Okamoto Kotaro , Imai Tetsuji
Published: November 2005

Films of SiO2, W and W/SiO2 have been applied as masks for the selective epitaxial growth of GaAs by metalorganic chemical vapor deposition (MOCVD). The deposition selectiveties on SiO2 masks are mainly due to a difference in the absorption coefficients of reactant species between SiO2 and GaAs, while those on W masks are due to the surface migration of reactant species. Reactant species migrating on the surfaces of W masks are (finally) used in the epitaxial growth of opening windows, and selective epitaxial growth maintaining mask surfaces completely free from deposition have been attained for samples in which mask patterns are narrower than 40 µm.
Current Oscillation in Semiconductors with a Dumbbell-Shaped Structure
Authors: Hirasawa Masao , Murayama Takashi , Oinuma Morihide , Kuwano Hiroshi
Published: November 2005

The necessary conditions for the occurrence of current oscillation, observed in the current-saturation regime regarding the current-voltage characteristics of semiconductors with a dumbbell-shaped structure, have been investigated by varying the carrier densities through illumination and heat. It is necessary to establish an oscillation of the space-charge layer in the wide region at the anode side at the devices. It is also necessary that the electric field at the boundary between the wide region on the anode side and the narrow region exceeds a critical value, above which the velocity of electrons or holes deviates from Ohm's law and becomes saturated.
Measurement of ICF Plasma Parameters by the Activation Method
Authors: Tsuji Ryusuke , Nishihara Katsunobu , Ido Shunji
Published: November 2005

A new and simple method is presented to measure ICF plasma parameters such as fuel ρR
DT, pusher ρΔ
R
SiO2
and DT reaction number N
react. To obtain those values simultaneously, the method uses at least three different activation test pieces with cross sections which have varying dependence on neutron energy. The Neutron energy spectrum becomes soft as ρR
DT and ρΔ
R
SiO2
increase. The number of activation reactions changes with the neutron energy spectrum. It is shown that the values of ρR
DT, ρΔ
R
SiO2
and N
react are obtained from two ratios among the observed activation numbers. An analysis of the method and its application to ICF plasma are presented utilizing Cu, Al, Ni and Si as activation test pieces.
On Induction Periods of Shock-Heated Methane-Oxygen-Argon-Mixtures
Authors: Tsuboi Takao , Katoh Masataka
Published: November 2005

The induction periods of shock-heated methane-oxygen-argon-mixtures were measured over a wide range of mixture ratios. The methane decay behind the reflected shock wave was monitored using an InSb-photodiode at a wavelength of 3.43 µm. Both the measured induction periods and the observed emission profiles were compared with the values obtained from computer simulation using reaction kinetics. The results were as follows: (1) The emission intensity at 3.43 µm in-creased during the induction period in a mixture less diluted with argon, while that of a mixture highly diluted with argon remained constant. If the reaction step CH3+O2=CH2O+OH is replaced with the step CH3+O2=CH3O+O in the methane oxidation mechanism developed in the authors' laboratory, the calculated induction periods agree well with the measured ones over a wide range of mixture ratios.
Amorphous Silicon Resistive Sea for Silicon Vidicon Targets
Authors: Mimura Hidenori , Hatanaka Yoshinori , Nogami Minoru
Published: November 2005

In this experiment, GD a-Si film was studied as a bakeout-proof resistive sea for a silicon-diode-array camera-tube target. It was found that the resistivity of an a-Si film deposited at temperatures between 400 and 600°C lay in the range 10-7–10-9 Ωcm, and that the film was suitable for used as a resistive sea when baked out in a vacuum at a temperature below 350°C. An Si target with an a-Si resistive sea from 40 nm to 1 µm thick, deposited at about 400–500°C, was baked in a vacuum at 350°C for two hours and then mounted in a camera tube, giving improved bakeout-proof and X-ray protection characteristics, and low lag.
Double Zinc Diffusion Fronts in InP: Correlation with Models of Varying Charge Transfer during Interstitial-Substitutional Interchange
Authors: Kazmierski K. , Cremoux B. de
Published: November 2005

Two concurrent models of interstitial-substitutional interchange involving more than one charge transfer are considered. The assumption of charged vacancy centers is shown to give a model consistent with the experimental data.
Interference and Pair Correlation Functions of Crystalline Embryo Model of Amorphous Metals. II
Authors: Hamada Tadashi , Fujita Francisco Eiichi
Published: November 2005

In order to improve the simple crystalline embryo model of amorphous metals proposed previously, the composite type embryo model for amorphous Fe-B alloy is constructed on a computer by assuming that the b.c.c. like embryos and chemical clusters of Fe3B type coexist. The interference function and pair correlation function are also calculated. To make a reasonable comparison with the experimental data, a new process of Fourier transformation, that takes account of the truncation effect, is successfully applied to the structural model. The two functions are in good agreement with experiment when the embryo size is taken to be as small as 10 A in diameter corresponding to the 15 core atoms cluster. It is concluded that the crystalline embryo model satisfactorily describes the amorphous structure.
Electrical Resistivity of Erbium Purified by Solid-State Electro-Transport Method
Authors: Maezawa Kunihiko , Saito Yoshitami , Wakabayashi Shigeru
Published: November 2005

A solid-state electro-transport method was used to purify erbium, increasing the residual resistance ratio of the metal from 4 to 46. It was observed that the migration of major impurities in erbium is directed toward the anode and that on environmental atmospheric pressure of the order of 10-10Torr is required for impurity migration to occur. The electrical resistivity and magnetic transition temperature were measured with purified erbium samples, and the Néel temperature, the intermediate temperature, and the Curie temperature were found to be 88 K, 55 K and 19 K, respectively, for the purest specimen. Furthermore, a jump was found to occur in the resistivity curve at 27 K. The values of the above temperature veried from specimen to specimen.
Anomalous Discharge Current in Polyethylene (PE), Ethylene-Vinylacetate Copolymer (EVA) and PE-EVA Laminated Films
Authors: Kitani Isamu , Arii Kiyomitsu
Published: November 2005

Conduction currents and discharge currents were measured in polyethylene (PE), ethylene-vinylacetate copolymer (EVA) and PE-EVA laminated films. Anomalous discharge currents (ADC) flowing in the same direction as the charging current were observed at 10–45°C in EVA, at 25–50°C in +PE-EVA-, of which PE side was applied to positive voltage, and at 25–60°C in PE and -PE-EVA+ with evaporated silver electrodes after application of a field of strength 2.0×108V/m. The electrode material affects the ADC peak in EVA. The results are discussed on the basis of the previous reported analytic conclusions; the ADC is caused by two types of injected charges (electrons and holes).
Alloy Fluctuation Effect on Electronic Transition Properties of DX Center Observed with Modified Deep Level Transient Spectroscopy
Authors: Takikawa Masahiko , Ozeki Masashi
Published: November 2005

Alloy fluctuation effects in electronic transition properties of the DX center have been studied in a selectively Si doped Al0.3Ga0.7As/GaAs heterostructure grown by molecular beam epitaxy. Using deep-level-transient-spectroscopy (DLTS) technique, we have measured the drain current transient, from an applied sale pulse for a long gate high-electron-mobility-transistor biased in a linear region. This scheme enables us to record DLTS-like spectra not only for the electron emission process but also for the electron capture process of the DX center. From the analysis of these spectra, we found capture and emission activation energies with Gaussian distributions having wide and narrow band-widths, respectively. This can be explained by considering the large fluctuations of electronic states and the small fluctuations of the spring constant and Jahn-Teller splitting parameter in the DX center cell.
Neutrons, X-Rays and Charged Particle Beams Emission in a 65 kV Plasma Focus
Authors: Yamamoto Toshikazu , Shimoda Katsuji , Hirano Katsumi
Published: November 2005

The correlation between the dynamic behaviour of a focused plasma and the bursts of neutrons, X-rays and charged particle beams have been investigated experimentally using a 65 kV plasma focus device. The dynamic bahaviour has been observed with a Mach-Zehnder interferometric system operating in the framing mode. The ion- and the electron beams are detected by a Thomson parabola analyzer and a Čerenkov detector, respectively. Neutrons, X-rays and charged particle beams are produced when a voltage spike appears. The generation of the electron- and the ion beam occur in an interval of 20 ns around the peak of the voltage spike. The m=0 type instabilities are observed even if the voltage spike does not appear. The plasma inductance increases monotonically but rather slowly during the process of the m=0 type instability growth. The neutron yield is ascribed to a generation of the anomalous resistivity in the plasma.
dc SQUID Microwave-Induced Characteristics and Magnetic Field Response, Derived Using the Stewart-McCumber Model
Authors: Naito Seiichi
Published: November 2005

This paper describes the I-V characteristics (as a function of applied magnetic field) and magnetic field response of a dc SQUID which incorporates two weak-link Josephson junctions in a superconducting ring. These characteristics are derived by digital computer simulation, using the Stewart-McCumber model. The effects of asymmetry (dissimilarity between the junctions) on SQUID critical current I
c, normal resistance R and capacitance C are also simulated.
With microwave excitation applied, the Josephson oscillations of the dc SQUID are found to be “frequency-locked” to the applied microwave signal even when critical currents I
c of the two junctions differed, Subharmonic voltage steps are obtained for a symmetric dc SQUID in a magnetic field even when the current-phase relationship is purely sinusoidal.
A Method of π0 Energy Reconstruction
Authors: Nakano Itsuo , Miyake Kozo
Published: November 2005

We present a method of π0 energy reconstruction by measuring two decay photon energies from a π0 meson and their opening angle. Although most high-energy photon detectors display an energy dependence on the energy resolution (FWHM) which is proportional to 1/√E, the resolution is poor for low-energy photons, this method improves there constructed π0 energy resolution. The method gives a simple analytic formula by taking into account the energy dependence of the photon-energy resolution of detectors such as lead-glass Cherenkov counters. It is verified by a Monte Carlo calculation that the method is more accurate and more reliable than other methods. The method is applicable to a particle which decays into two photons, such as an η meson.
H2-Enhanced Epitaxial Regrowth of Polycrystalline Silicon through Natural Oxide Layers on Silicon Substrates
Authors: Kugimiya Koichi , Hirofuji Yuichi
Published: November 2005

Poly- to single-crystal Si epitaxial regrowth by H2 annealing was achieved even in the presence of thick interfacial oxide layers up to 2 nm thick. The epitaxial regrowth took place through anomalous layers after the coalescence of the interfacial oxide layers to oxide precipitates. Twins and stacking faults were also grown at the interfaces when the epitaxial regrowth was initiated on the substrates at numerous openings in clusters of the oxide precipitates.
TEM and SIMS analyses confirmed a previously-proposed schematic model of the epitaxial regrowth by H2 annealing and showed that the anomalous layers were composed of coalesced oxide layers and layers supersaturated with oxygen.
Si-Beam Radiation Cleaning in Molecular-Beam Epitaxy
Authors: Kugimiya Koichi , Hirofuji Yuichi , Matsuo Naoto
Published: November 2005

A new surface-cleaning process for Si-MBE, termed Si-beam radiation cleaning (Rad clean), and a model of the cleaning process have been examined. Epitaxial Si layers of high quality have been obtained as a result of the formation of an inactive, very clean natual oxide, removal of this oxide together with contaminants slightly adsorbed on it, and dispersion of remaining contaminants without their developing into defect nuclei.
Epitaxial Si layers with etch pit densities of less than 103/cm2 have reproducibly been obtained by carrying out growth at 500°C following the Rad clean process at 800°C for 2 min.