bluuebunny/crossref_metadata_2025 huggingface dataset:
ESR Study of X-Irradiated NaNO3
Authors: Tagaya Kimihito
Published: November 2005

Single crystals of NaNO3 were irradiated with X-rays at room temperature, and ESR measurements were performed over the temperature range from 85 K to room temperature. It was concluded that F, O2
-, O3
-, NO2 and NO2
2- centers were produced. The sites and orientations of the centers in an NaNO3 crystal were determined from the principal directions of the g or hyperfine tensor. The superhyperfine interactions of F, O2
- and NO2 centers with adjacent 23Na and 14N nuclei were investigated, and the superhyperfine-tensor components were determined. Further, isothermal annealing measurements were performed for the F-center.
Relaxation Spectroscopy of the Mechanical β-Relaxation in Poly(n-alkyl methacrylate)s in Glassy State by Stress Relaxation Measurements
Authors: Kakizaki Maeko , Murata Kazutaka , Hideshima Teruo
Published: November 2005

The validity of the time-temperature reducibility and the similarity between the mechanical and dielectric relaxations were examined in the case of the β-relaxation due to motion of the side chains in polymethyl, polyethyl and poly-n-propyl methacrylates by stress relaxation measurements. The shear relaxation modules was measured from 5 sec to 900 sec in the temperature range fromca. -110°C toca. 30°C. Using these data, it is shown that the time-temperature reducibility is valid for the β-relaxation in the glassy state below a certain critical temperature, and that activation energy and shape of the relaxation spectrum are independent of side-chain length while relaxation strength is proportional to the number of side chains in unit volume as in the case of the dielectric β-relaxation. The applicability of the two-site model is also examined.
Distribution of Free Volume and Dielectric Relaxation due to Segmental Motion of Amorphous Chains in Chlorinated Poly(ethylene)
Authors: Kakizaki Maeko , Abe Yoshio , Hideshima Teruo
Published: November 2005

The temperature dependence of the shape of the loss permittivity versus frequency plot for the dielectric relaxation due to the segmental motion of amorphous chains in chlorinated poly(ethylene) is explained by a simple theory of the distribution of free volume.
The assumptions on which the theory is based are; (1) the free volume distribution obeys the Γ-distribution; (2) the relaxation time depends on the free volume fraction according to a Doolittle-type equation, (3) the relaxation behavior of this process is described by the Williams-Watts' equation.
It is also shown that this temperature dependence of the shape of the loss-permittivity curve cannot be explained by a theory of distribution of activation energies.
Trapping Criterion for Deuterium Cluster Ions in an Accelerator Using an Accelerating Potential Wave
Authors: Kawaguchi Motoichi , Suzuki Hiroshi , Enjoji Hiroshi
Published: November 2005

The behavior of cluster ions in an accelerating potential well is discussed in terms of a collective accelerator of cluster ions. By studying the time variation of the potential energy and the energy-like quantity of cluster ions, the trapping criterion in the accelerating potential well is obtained in an analytic form, which makes a simple calculation of acceleration efficiency possible for arbitrary distributions of the mass and initial injection phase of cluster ions. For a Gaussian mass distribution and continuous uniform injection, the efficiency amounts to 70%.
Electronic States In Glow-Discharge a-SiGex:H:(F) Alloys
Authors: Oda Shunri , Takagi Sakae , Shimizu Isamu
Published: November 2005

Amorphous SiGe
x
films with low spin densities and high photoconductivity were prepared by the glow discharge of a gaseous mixture of SiF4-GeF4-H2. The transport properties of a-SiGe
x
:H:(F) were investigated by the time-of-flight method. The electron transport was found to be non-dispersive at room temperature with a drift mobility of 0.2-0.3 cm2/ Vs, while the transient hole current consisted of a fast non-dispersive process and slow emission from deep states. The non-dispersive hole transport may be due to narrow tail states of the valence band. The nature of the deep defect states in a-SiGe
x
:H:(F) is disscussed in terms of a defect type consisting of twofold-coordinated Ge.
Effect of H2 Plasma Etching during Glow-Discharge Deposition of Amorphous Carbon Films
Authors: Nishikawa Satoshi , Kakinuma Hiroaki , Fukuda Hisashi , Watanabe Tsukasa , Nihei Koji
Published: November 2005

Amorphous carbon films were prepared by the glow-discharge decomposition of C2H2, C2H4, and C2F6 at various rf powers and substrate temperatures (T
s). The deposition rate (DR) of a-C:H and a-C:H:F decreases with increase in T
s. These results are discussed in terms of the H-plasma etching of a-C:H films during the deposition. The optical, electrical and structural properties of the a-C:H films are also examined as a function of the rf power.
Effect of Annealing on Photoinduced Absorption in Amorphous Silicon Films Prepared at High Deposition Rates
Authors: Ueda Masato , Chayahara Akiyoshi , Nakashita Toshio , Imura Takeshi , Osaka Yukio
Published: November 2005

The effects of annealing on the photoinduced optical absorption (PA) of hydrogenated amorphous silicon films prepared at a high deposition rate of ∼4.5 nm/s have been investigated in relation to the changes in structural and optical properties induced by annealing. The variation of the thermoresistivity with the hydrogen effusion from the film is compared with that in low-deposition-rate films, and it is concluded that trapped hole states near the valence band (A-centers) inducing most of the PA are correlated with the presence of hydrogen in a-Si:H films. The structural relaxation produced by annealing up to 400°C is accompanied by a reduction in the gap and tail state density near the conduction-band edge.
Influence of RF Power on Properties of a-Si1-xGex:H Prepared by RF Glow Discharge Decomposition
Authors: Nishikawa Satoshi , Kakinuma Hiroaki , Watanabe Tsukasa , Nihei Kouji
Published: November 2005

The electrical and structural properties of hydrogenated amorphous silicon germanium alloys prepared by the rf glow discharge method have been measured as a function of the rf power and the gas flow rate. The photoconductivity of a-Si1-x
Ge
x
:H films increases by a factor of 103 at x=0.45 with increasing rf power density, and the microstructure of the films changes from heterogeneous to homogeneous. This paper discusses the deposition mechanism inducing these results.
Two-Dimensional Model on Impurity Segregation in InSb Pulled Crystal
Authors: Hayakawa Yasuhiro , Ishikawa Kenji , Kumagawa Masashi
Published: November 2005

A two-dimensional model of a time function is proposed to investigate the relation between the growth rate and spreading resistance in the facet and off-facet regions of an InSb pulled crystal, which contains local remelt near the crystal periphery. The calculated results agree qualitatively with the experimental ones.
Phenomenological Considerations on the Photoconduction of Plasma-Polymerized Styrene Films in the Near-Ultraviolet Region
Authors: Sawa Goro , Murata Takaaki , Ohara Motoyasu , Sunda Fumihiro , Nakamura Shuhei
Published: November 2005

The photoconduction of plasma-polymerized styrene films was studied in the near ultraviolet region. The spectral response was independent of the polarity of the applied voltage and showed two photocurrent peaks at wavelengths of about 300 nm and 375 nm. These photocurrent peaks were nearly proportional to the 1.5 power of the applied electric field and the 0.85-0.86 power of the light intensity and inversely proportional to the film thickness, provided that the thickness exceeded the absorption depth. The response to step illumination exhibited a small but definite decay at a rate which increased with increasing film thickness. These characteristics are consistently explained by the existence of a partially photoconductive region near the illuminated surface.
Depth Profiling of Si-SiO2 Interface Structures
Authors: Suzuki Toshihisa , Muto Masaaki , Hara Motohiro , Yamabe Kikuo , Hattori Takeo
Published: November 2005

The Si-SiO2 interface structures of thermally grown oxide films on (100) surfaces were studied using three types of depth profiling measurement. Analysis of these measurements confirms the interface structures determined previously by nondestructive depth profiling.1) The appicability of chemical depth profiling to the study of interface structures was also studied. A new method of spectral analysis, used successfully in the present measurements, is presented.
A Structural Study of Co-Sb Multilayered Film by X-Ray Diffraction
Authors: Nakayama Noriaki , Takahashi Koyata , Shinjo Teruya , Takada Toshio , Ichinose Hideki
Published: November 2005

The structure of a multilayered film, [Co(30 Å)-Sb(25 Å)]70, prepared by vacuum deposition is investigated by using mainly X-ray diffraction. It is revealed that the Co layer has a hcp structure with [110] texture while the Sb layer does not show any distinct texture. The relative intensities and the line width of Bragg reflections are interpreted on the assumption of a very thin compound layer at each interface and also a small distribution of Sb layer thickness. Preliminary results from electron microscopic analyses are also briefly introduced.
Photoluminescence Excitation Spectroscopy of In0.53Ga0.47As/InP Multi-Quantum-Well Heterostructures
Authors: Kodama Kunihiko , Komeno Junji , Hoshino Masataka , Ozeki Masashi
Published: November 2005

The photoluminescence and, for the first time, the excitation spectra of In0.53Ga0.47As/InP multi-quantum-well structures were measured at 4.2 K. Emission bands were observed below E
1h as well as at E
1h, where E
1h denotes the n = 1 electron-heavy-hole free-exciton transition. The emission below E
1h was found from the excitation spectra to be in striking contrast to the band-acceptor transition in thick In0.53Ga0.47As layers. Its luminescent intensity decreases very slowly or show little decrease as the photon energy of excitation decreases below E
1h. This emission is believed to be related to the n = 1 electron quantum state-acceptor transition. Fluctuation of quantum levels due to strain in the interdiffused layers at the heterointerfaces is thought to be a possible origin of the anomalous excitation spectra.
Nb Surface Effects on the Properties of Nb Oxide Barrier Junctions Prepared Using a CF4 Cleaning Process
Authors: Asano Hidefumi , Michikami Osamu
Published: November 2005

The Nb surface effects on junction characteristics were investigated in Nb/oxide/Pb junctions in which the base electrode was cleaned by an Ar+CF4 mixture plasma. The oxide barrier was grown by rf plasma oxidation on polycrystalline and single-crystal Nb films (R
R
R=4-135). It was confirmed that Nb grain size affected Nb penetration depth, transition temperature, and junction gap structure. However, high junction quality (V
m> 30 mV) and high barrier height (φ∼1.0 eV) were obtained independent of the existence of Nb grain boundaries. Based on these results and previous XPS findings, that is, the formation of a thin Nb-F-O layer on a CF4 cleaned Nb surface, it is surmised that this thin layer deactivates the grain boundary region and reduces the problems associated with this region.
Parametric Transducer for Gravitational Radiation Detector
Authors: Tsubono Kimio , Ohashi Masatake , Hirakawa Hiromasa
Published: November 2005

A low-noise parametric vibration transducer using a pair of superconducting microwave cavities has been developed for use with cryogenic gravitational radiation antennas. Pumped by a 9.7-GHz SCSO, the cavities convert mechanical vibration into microwave sidebands which, after demodulation, reproduce the low-frequency signal. For the performance test of the transducer system, the cavities were mounted on a 15-kHz prototype disk antenna at 4.2 K. A transducer noise temperature of 23 mK was obtained at the antenna frequency, and hence a quantum noise number of 3.4×104.
A Method of Determining the Sense and Magnitude of Optical Rotation in Uniaxial Crystals, together with a Study of the Gyrotropic Phase Transition of CsCuCl3
Authors: Sano Motoaki , Iio Katsunori , Nagata Kazukiyo
Published: November 2005

A method of determining the sense and magnitude of the optical rotatory power of unixial crystals has been developed, and has been used to measure the optical activity of CsCuCl3, a gyrotropic crystal. Virgin crystals grown from aqueous solution were found to be predominantly dextrorotatory, though a crystal with a single gyrotropic domain was rarely found. The racemization effect was produced when the temperature was reduced through the gyrotropic phase transition point at about 420 K.
Performance of Parallel-Plate Electron Spectrometer with Position-Sensitive Detector
Authors: Yagishita Akira
Published: November 2005

A new electron spectrometer system consisting of a parallel-plate energy analyzer combined with a position-sensitive detector assembly has been developed. The performance of the new system was studied, and the system was found to give an efficiency two orders of magnitude greater than that of conventional spectrometers. The new system was attached to a beam line at the Photon Factory at Tsukuba and was used to measure the degree of polarization of monochromatized synchrotron radiation.
“ε-Scanning”–A Method of Evaluating the Dimensional and Orientational Distribution of Crystallites by X-Ray Powder Diffractometer
Authors: Yukino Ken , Uno Ryosei
Published: November 2005

When a specimen is rocked about the θ axis of an X-ray powder diffractometer with the detector fixed at a given Bragg peak 2θB, the resulting diffraction pattern reflects both the dimensional and the orientational distribution features of the crystallites in the specimen. For instance, reproducible fluctuations in the pattern can be attributed to coarse crystallites in the specimen, and the magnitude of the fluctuations corresponds to that of the peak intensity obtained by the θ-2θ scanning method, whereas a systematic deviation of the averaged pattern from that estimated from the absorption factor gives the angular dependence of the preferred orientation of the specimen directly. This method of evaluating the specimen using the X-ray powder diffractometer is reliable and convenient because of its applicability under the same experimental conditions as in the usual θ-2θ scanning method.
Growth Mechanism of ZnS and ZnSe Films in Low-Pressure MOCVD
Authors: Yoshikawa Akihiko , Sirai Atsuhisa , Yamaga Shigeki , Kasai Haruo
Published: November 2005

The growth mechanism of ZnS and ZnSe films in low-pressure MOCVD has been studied by observing the effects of the growth conditions on the growth rate of the films. The substrate temperature, flow rate of source materials, pressure in reactor, and [VI]/[II] molar ratio were varied, and the growth rate was found to be strongly affected by the pressure in the reactor as well as other growth conditions. The increase of the growth rate with pressure is attributed to an increase in the sticking coefficient of DMZn (or its complexes) with pressure. Furthermore, a decrease in growth rate at higher substrate temperatures was also attributed to a change in the sticking coefficient. It is shown that the sticking coefficient of DMZn (or its complexes) is an important factor in the MOCVD growth of II-VI compounds.
Nucleation and Growth of Stress Relief Patterns in Sputtered Molybdenum Films
Authors: Ogawa Keiichi , Ohkoshi Tsuneo , Takeuchi Tomoyuki , Mizoguchi Tadashi , Masumoto Tsuyoshi
Published: November 2005

Stress relief patterns in sputtered molybdenum films were studied by Nomarski differential interference contrast microscope. As a result of the very large biaxial compressive stress in the film plane, ranging from E/16 to E/130 (where E is Young's modulus), the films were partially buckled and detached from the substrate, exhibiting one of two modes of stress relief pattern, wrinkled spots or wavy ridges. The former mode is a nucleation pattern and the latter a growth pattern. The transition between the two can be interpreted in terms of the stress intensity factor K
1 at the head of the gap formed due to stress between the film and the substrate. K
1 can be regarded as measure of the bond strength between the film and the substrate.
Magnetic Torque Curve of a System Containing Three Uniaxial Regions (Calculation and Model Experiment)
Authors: Miyata Nahonori , Hagiwara Makoto , Ichiyanagi Yuko
Published: November 2005

The magnetic field dependence of the torque curves of a ferromagnetic material containing three different regions with uniaxial anisotropy in mutually rectangular alignment was estimated from numerical calculation and an experiment using a model. Two cases, in which the rotation axis corresponded to the [001] and [111]-axes in a cubic crystal, were treated. The calculation was based on a magnetization process in which the magnetic interaction among different regions was assumed to be negligible. The magnetic field dependence of each Fourier component of the torque curve was expressed by a polynomial form of the inverse of the magnetic field, and the coefficient of each term was determined. The experiment was carried out using a model sample made of three nickel wires with their axes aligned at right-angles. The experimental results agreed with the calculation.
Behavior of a Confined Plane Jet in a Rectangular Channel at Low Reynolds Number I. General Flow Characteristics
Authors: Ouwa Yasuhiro , Watanabe Masaaki , Matsuoka Yoshihiro
Published: November 2005

The detailed characteristics of confined symmetric, asymmetric and wall jets at low Reynolds numbers were studied using the visualization technique and laser Doppler velocimetry. The behavior of these three different types of jet was found to be characterized by the aspect ratio of the rectangular channel used. Thus, no differences among the jets were found regarding the separation, the reattachment length and the conditions of instability of the jet flows. Furthermore, the three-dimensional effect of the flow was examined in detail by visualizing the secondary flow. The velocity distributions across the channel were measured by laser Doppler velocimetry and compared with those obtained by numerical analysis.
Construction of GaAs Spin-Polarized Electron Source and Measurements of Electron Polarization
Authors: Nakanishi Tsutomu , Dohmae Kazuhiko , Fukui Shuji , Hayashi Yoshikazu , Hirose Ikuo , Horikawa Naoaki , Ikoma Tetsuaki , Kamiya Yoshihiro , Kurashina Mitsuru , Okumi Shoji
Published: November 2005

A simple and compact system for generation and detection of polarized electrons is constructed. Polarized electrons are extracted from negative electron affinity (NEA) surface of GaAs by optical pumping with circulary polarized light from GaAlAs laser diode. The maximum degree of the electron polarization measured by 90 keV Mott analyzer is about ±10%.
Experimental Confirmation of Angular Dependence of Rayleigh Line Spectral Width in Nematic Liquid Crystals
Authors: Akiyama Ryuichi , Tomida Koumei , Fukuda Atsuo , Kuze Eichi
Published: November 2005

We compared calculated results with experimental data on the scattering angular dependence of the relaxation time corresponding to the Rayleigh line spectral width obtained by using a homeotropically- and homogeneously-aligned cell to check the validity of the Orsays formulas for the dynamic behavior of the director modes and the accuracy of scattering measurements. However, to increase the strength of the scattered intensity, we tilted the cell, thus changing the angle φ' between the incident light and the director over a range of -30°≤φ'≤30° and 60°≤φ'≤120°, while keeping the director in the scattering plane. All measurements were made using the homodyne technique. The obtained experimental data were within an accuracy of 0.1% for the refractive index, 5% for the elastic constant ratio and 3% for the relaxation time. Experimental results indicate that the Leslie viscosity coefficients µ1 and µ3 of MBBA are very small in comparison with the four other coefficients. By using the twist elastic constant K
2, other Leslie viscosity coefficients can be given as µ2/K
2=-26×109, µ4/K
2=20×109, µ5/K
2=16×109 and µ6/K
2=-10×109 in kgm-1s-1/N at a temperature T-T
NI=-21°C (nematic-isotropic transition temperature T
NI=46.2°C). Temperature variations in the relaxation time for splay, twist and bend deformation are also described.
Analysis of ac Surface Photovoltages in a Depleted Oxidized p-Type Silicon Wafer
Authors: Munakata Chusuke , Nishimatsu Shigeru
Published: November 2005

The majority carrier conductance due to the hole flow towards the surface of a wafer from the bulk has been formulated following the half-sided junction model previously reported. An empirical equation for the carrier drift velocities in very high electric fields has been proposed for the formulation. Besides the conductance, the depletion layer capacitance, interface trap capacitance and conductance are found to be responsible for ac surface photovoltages in the depletion case. The majority carrier conductance can explain the formerly observed conductance of 27 S/m2 in a 76-mm-diameter 1.0-mΩm oxidized p-type Si wafer. Analysis of the formerly reported surface photovoltages reveals a surface potential, fixed oxide charge density, hole capture cross section and interface trap density of 0.32 V, 1.7 mC/m2, 2.0×10-20 m2 and 2.0×1016 m-2 eV1 respectively.
Use of In-Zn-As Ternary Sources for the Diffusion of Zn in GaAs by the Semiclosed-Box Method
Authors: Launay F. , Kazmierski K. , Huber A. , Cremoux B. de
Published: November 2005

Liquid sources consisting of the In-Zn-As ternary system have been successfully used for the diffusion of Zn in GaAs by the semiclosed-box method. The surface concentration and junction depth were easily controlled over a wide range of source composition. The experimentally observed effects of the zinc and arsenic fractions in the source on the diffusion agree well with a model derived from interstitial-substitutional interchange.
Superconductor-Base Hot-Electron Transistor. II. Fabrication and Electrical Measurement
Authors: Sakai Hiroyuki , Kurita Yoshiyuki , Tonouchi Masayoshi , Kobayashi Takeshi
Published: November 2005

Superconductor-base hot-electron transistors (Super-HETs) comprising n+-GaAs/Nb(or NbN)/α-InSb/Au multiplelayers were fabricated and electrical measurements were made at liquid-helium temperature. The observed hot-electron transport efficiency was as high as 80% for a device with a 200Å thick Nb base, close to the theoretical 90%. A device with a 600Å NbN base exhibited an efficiency of 60%. The sputtered InSb film served as a suitable collector barrier with a lower barrier height and an extremely reduced quantum mechanical reflection for incident hot-electrons. However, the space-charge limited current was still limited to the lower value, probably due to residual defects.
Photochromic Properties of Sodium Halide Crystals Sensitized with Sulfur
Authors: Baba Mamoru , Kimura Norio , Ikeda Toshio
Published: November 2005

NaCl and NaBr crystals sensitized with sulfur ions show a coloration due to the formation of F centers upon irradiation by ultraviolet light. F-light or white-light irradiation onto a colored specimen induces a bleaching of F centers. In this bleaching process, some of the sulfur ions return to their initial states. Therefore, these crystals can be used as photochromic materials having the property of reversible color change. Coloring and bleaching characteristics have been investigated and the value of γ was determined to be about 0.4 for the coloring process and about 0.5 for the bleaching process. In a specimen with a higher concentration of dispersed sulfur ions, some of the F centers aggregate to form X centers during the bleaching process. Coloration due to the formation of X centers is highly stable at room temperature and is suitable for long-time information storage.
Electrical and Optical Properties of Poly(p-phenylene vinylene) and Effects of Electrochemical Doping
Authors: Yoshino Katsumi , Takiguchi Tohru , Hayashi Shigenori , Park Dae Hee , Sugimoto Ryu-ichi
Published: November 2005

Electrical conductivity, ESR spectra, optical absorption spectra of poly(p-phenylene vinylene) (PPV) and their dependence on doping are discussed in detail. The band gap of PPV was evaluated to be 2.7 eV, intermediate between those of polyacetylene and poly(p-phenylene). The evolution of localized states is evidenced by the spectral change with electrochemical doping. The results are interpreted in terms of the polaron and bi-polaron models.
Photovoltaic Effect and Luminescences of AlxGa1-xSb Ternary Alloy Semiconductors
Authors: Sonomura Hajimu , Morimoto Taiji , Horinaka Hiromichi , Miyauchi Takeshi
Published: November 2005

Single crystals of Al
x
Ga1-x
Sb were prepared by the solution growth method, and the band gaps of the alloys were derived from the photovoltaic responses obtained at room temperature. The polarity of the photovoltage shows intentionally undoped alloys to be n-type, in contrast to the usual results. This is due to the large amount of Si impurities introduced from the quartz container by reaction with Al during the high-temperature growth. The photo- and electroluminescent spectra were measured at 80 K, and three series of peaks were observed in both luminescences. These are interpreted in terms of recombinations of interband transitions, via Si impurities and residual impurities, perhaps Sb vacancies, which always exist in undoped GaSb.
High Threshold Voltage Reproducibility for WSi/AlxGa1-xAs/GaAs MIS-Like Heterostructure FET
Authors: Maruo Tetsuya , Arai Kunihiro , Yanagawa Fumihiko
Published: November 2005

A WSi gate Al
x
Ga1-x
As/GaAs MIS-like heterostructure FET was fabricated. The threshold voltage of this FET is independent of the Al
x
Ga1-x
As barrier-layer thickness in contrast with that of an HEMT. There is little variation in the threshold voltage (0.05 V) against a large change in the barrier-layer thickness. This ensures a uniform threshold voltage as well as the reproducibility of this FET.
On Applicability of Laser-Induced Fluorescence from the Metastable State of Argon Ions to Ion Density Measurements
Authors: Watanabe Yukio , Shiratani Masaharu , Ogi Sukeomi , Takamatsu Masahiro , Kunihiro Naoki
Published: November 2005

Laser-induced fluorescence (LIF) from an Ar+ metastable state was detected in low-pressure DC discharge plasmas. The dependence of the 3d4F and 4p2D population densities on the discharge current was examined with a collisional-radiative model (C-R model). The results show that information on the ion density can be obtained from LIF by using the C-R model when the electron temperature is known.
Coaxial Laser-Induced Fluorescense Spectroscopic System for Impurity Diagnostics in Plasmas
Authors: Hamamoto Makoto , Ohgo Tadashi , Kondo Katsumi , Oda Toshiatsu , Iiyoshi Atsuo , Uo Koji
Published: November 2005

A coaxial optical system for laser-induced fluorescence spectroscopy which uses only one observation port has been developed. This system can be used to investigate the behavior of metal impurities in the region where the plasma interacts with the wall in a magnetic confinement device which has no suitable pair of observation ports.
The spatial resolution along the axis and the absolute sensitivity of the coaxial optical system were investigated using iron vapor generated in a Knudsen cell. The lower limit of the detectable iron density in this experiment is estimated to be 4×1013 m-3.
The coaxial optical system has also been demonstrated to be useful for reducing the fluorescence produced by the window material, a serious disadvantage in conventional coaxial optics.
Study of the Commensurate Superstructure in 4Hb–TaS2 by High Resolution Electron Microscopy
Authors: Kuwabara Masago , Hashimoto Hatsujiro , Endoh Hisamitsu
Published: November 2005

The commensurate superstructures caused by CDW in 4Hb–TaS2 have been investigated by a high resolution electron microscope at room temperature. It was found that the two types of √13a × √13a superstructures, which rotated ±13.9° from a-axis in 00.1 plane, coexist in the same region, not in same layers but in different layers which have octahedral coordination. The two types of superstructure occur with different probabilities whose ratio depends on the samples. It was also observed that these superstructures were not greatly affected by dislocations in the crystal.
Selective Embedded Growth of AlxGa1-xAs by Low-Pressure Organometallic Vapor Phase Epitaxy
Authors: Kamon Koichi , Takagishi Shigenori , Mori Hideki
Published: November 2005

Selective embedded growth of Al
x
Ga1-x
As (x≤0.35) in grooves of patterned substrates has been achieved for the first time by low-pressure organometallic vapor phase epitaxy (LP-OMVPE). Epitaxial Al
x
Ga1-x
As layers are embedded only in chemically etched grooves, while no polycrystalline deposition occurs on the masked area. The layers grown in grooves with the reverse-mesa cross sections, formed in the [110] direction, are uniform in thickness and show flat-smooth surfaces throughout. These results indicate that LP-OMVPE is a very promising technique for monolithic device integration.
Possible Errors due to Deviation from the Cosine Response in the Reference Cell Calibration under Global Irradiance
Authors: Shimokawa Ryuichi , Miyake Yukiharu , Nakanishi Yuji , Kuwano Yukinori , Hamakawa Yoshihiro
Published: November 2005

The dependence of solar cell response on the incident beam angle was quantitatively examined using a monochromatic light beam with a wavelength range of 350 to 1150 nm. The results obtained for module-packaged, unpackaged and inert gas-sealed crystalline Si reference cells were compared with theoretical calculations. Next, the effect of incident sun angle on solar cell performance was theoretically investigated under global horizontal irradiance. The possible errors due to deviation from the cosine response were calculated in the reference cell calibration under global irradiance.
Bright Blue Electroluminescenee in SrS:CeCl3 Thin-Films
Authors: Tamura Yasuaki , Ohwaki Junichi , Kozawaguchi Haruki , Tsujiyama Bunjiro
Published: November 2005

The crystallinity of a SrS:CeCl3 active layer for a thin-film electroluminescent (EL) device is strongly affected by the underlayer. Bright blue emission is achieved in a thin-film EL device having a strongly cub.(111)-oriented ZnS film as its underlayer. The maximum brightness of the device is 1100 nt under 5 kHz sinusoidal voltage excitation. The EL characteristics are discussed in relation to the X-ray diffraction pattern and photoluminescence spectra of the active layer.
Performance of Plasma Erosion Opening Switches in High Voltage Pulsed Power Compression
Authors: Miyamoto Syuji , Yugami Noboru , Fujita Hirokazu , Ozaki Tetsu , Imasaki Kazuo , Nakai Sadao , Yamanaka Chiyoe
Published: November 2005

The plasma erosion opening switch was investigated for use in a pulsed power compression system. The effects of plasma injection velocity and injection polarity to the switch operation were studied experimentally. Using high injection velocity plasma, high impedance (up to 100 Ω) and high voltage (up to 6.4 MV) operation is possible. Comparison between experimental data and analytic calculations of the time history of the plasma erosion opening switch implied that a self magnetic pressure effect is important for fast, high impedance opening of the switch.
Microwave Performance of GaAs PBT's Fabricated from MO–CVD Wafers
Authors: Takanashi Yoshifumi , Asai Hiromitsu , Ando Seigo , Sugiura Hideo , Honda Takashi , Susa Nobuhiko
Published: November 2005

Microwave performance of GaAs PBT's fabricated from MO-CVD wafers is presented. Fabricated transistors operate as a mixed mode of pentode and triode. The transconductance of devices with active areas of 15 µm long by 50 µm wide is about 100 mS, corresponding to 35 mS/mm per equivalent gate width. The frequency at unity current gain ( f
T) and the maximum frequency of oscillation (f
max) are determined to be 7.5 GHz and 18 GHz, respectively, from s-parameter measurement.
Incorporation Effects of Nitrogen into Phosphorus Doped Microcrystalline Si:H Films
Authors: Hasegawa Seiichi , Tsukao Toshiya , Kurata Yoshihiro
Published: November 2005

Microcrystalline Si1-x
N
x
:H films were prepared by r.f. glow-discharge of SiH4–PH3–N2–H2 mixtures with the gas volume ratio of N2 to SiH4 maintained at 0.06. Incorporation effects of nitrogen on the electrical and optical properties, in connection with the degree of crystallization, have been investigated as a function of the substrate temperature T
s and r.f. power. The crystallization is observed at T
s between 250 and 400°C, but not at other T
s This is in good correspondence to the increase in dark conductivity. The degree of crystallization and optical gap increase with r.f. power. A model for the crystallization process is proposed.
Structural Disorder of Si(111)√3×√3-Au Surface Studied by LEED
Authors: Higashiyama Kazuyuki , Kono Shozo , Sagawa Takasi
Published: November 2005

LEED observation and analysis of the submonolayer interfaces of Au/Si(111) have been reported. It is shown that a well-ordered √3×√3 surface is not formed in this system. Instead, unusual √3×√3 LEED patterns appear with either diffuse, sharp and diffuse or sharp and ring-like spots depending on Au coverage. A kinematical analysis of the LEED patterns for various Au coverages implies that the unusual √3×√3 patterns are due to early stages of the formation of a 6×6 surface.
Low Temperature Polysilicon Super-Thin-Film Transistor (LSFT)
Authors: Noguchi Takashi , Hayashi Hisao , Ohshima Takefumi
Published: November 2005

Advanced polysilicon SFT's (Super-thin-Film Transistor) were fabricated on quartz at a low temperature process below 610°C. Using the technique of Si+ ion implanted amorphization and subsequent solid phase growth and making a super-thin-film structure, superior electrical characteristics such as high electron mobility of 60 cm2/(V·s) were obtained. The oscillation of a 19 stage ring oscillator with a channel length of 8.4 µm was observed. Propagation delay time of 8.13 ns/stage was attained. The device is expected to be applied to monolithic liquid-crystal-display on low temperature glass and three dimensional LSI technology.
On the Polymorphism of Titanium Dioxide Films Crystallized by Electron Beam Heating
Authors: Saito Yoshio , Kaito Chihiro , Naiki Toshio
Published: November 2005

Electron energy loss spectroscopy (EELS) and electron microscopy were conducted on the polymorphism of vacuum-deposited titanium dioxide films on a potassium chloride substrate. As-deposited amorphous films were crystallized to rutile and anatase modifications of titanium dioxide by intense electron beam irradiation. By EELS, tungsten from the evaporation source was found in all of the prepared films. Potassium and chlorine were also found in rutile and antase crystals, respectively. The appearance of the anatase crystals was attributed to incorporation of the chlorine impurities.
Two-Dimensional Electron Gas at GaAs/Ga0.52In0.48P Heterointerface Grown by Chloride Vapor-Phase Epitaxy
Authors: Kodama Kunihiko , Hoshino Masataka , Kitahara Kuninori , Takikawa Masahiko , Ozeki Masashi
Published: November 2005

We report the first observation of two-dimensional electron gas at GaAs/Ga0.52In0.48P heterointerfaces using the Shub-nikov-de Haas measurements. The heterostructures were prepared by chloride vapor-phase epitaxy. The sheet carrier concentration is higher than that in GaAs/n-AlxGa1-xAs heterostructures with a similar donor-concentration inn-AlxGa1-xAs layers. This may be attributed to the facts that the dominant donors in the Ga0.52In0.48P layers are shallow and that the conduction-band discontinuity at the GaAs/Ga0.52In0.48P interfaces is large.
Proton-Beam Propagation through Wall-Confined Plasma Channel Stabilized against Sausage Instability
Authors: Nakahama Masao , Nemoto Masahiro , Masugata Katsumi , Ito Michiaki , Matsui Masao , Yatsui Kiyoshi
Published: November 2005

Experimental results are presented of proton-beam (energy ∼650 keV) propagation through wall-confined plasma channel that is stabilized against sausage instability by an externally-applied longitudinal magnetic field. Significant improvement of beam-propagation efficiency has been obtained of ∼70% compared with the previous experiment of ∼55% without the magnetic field. The propagation can also be available up to ∼30% even in a non-propagation region in a non-stabilized channel.
GaAs Substrate Preparation for Oval-Defect Elimination during MBE Growth
Authors: Fronius H. , Fischer A. , Ploog K.
Published: November 2005

We have developed a new method for GaAs substrate preparation which significantly reduces the formation of oval defects during MBE growth of selectively doped n-Al
x
Ga1-x
As/GaAs heterostructures. The method simply requires treatment in H2SO4 after mechano-chemical polishing in NaOCl solution and generation of a protective surface oxide during In soldering. Routinely a density of oval defects of less than 200 cm-2 is achieved for 2 µm thick heterostructures. The efficiency of the new preparation procedure is demonstrated by 2DEG mobilities in excess of 106 cm2/(Vs) at 6 K obtained with a spacer width as narrow as 18 nm.
Implosion Property of Cannonball Target at 10.6 µm Laser Wavelength
Authors: Fujita Masayuki , Daido Hiroyuki , Terai Kiyohisa , Miki Futoshi , Kitagawa Yoneyoshi , Nakai Sadao , Yamanaka Chiyoe
Published: November 2005

Compressed core density of a Cannonball target of inner pellet irradiation type at 10.6 µm laser wavelength was measured using spectrally resolved neon X-ray emission. The implosion simulations by HIMICO code agreed well with the experimental results and showed that the dominant force of implosion is hot electron driven ablation pressure. Comparison of the simulation and experimental results clarified that the core density was compressed to 200 mg/cc due to the truncation of high energy electrons. We show that the hot electron driven Cannonball target is a feasible scheme for high density compression at 10.6 µm CO2 laser.
Splitting of Photoluminescence Spectra and Negative Differential Resistance Caused by the Electric Field Induced Resonant Coupling of Quantized Levels in GaAs–AlGaAs Multi-Quantum Well Structures
Authors: Furuta Tomofumi , Hirakawa Kazuhiko , Yoshino Junji , Sakaki Hiroyuki
Published: November 2005

Effects of the perpendicular electric field F

z
on the photoluminescence (PL) and photocurrent were studied at 77 K in a 150 A-GaAs/150 Al0.3Ga0.7As multi-quantum well structure having 15 periods. When F

z
was increased, the main PL peak was found to shift toward the longer wavelength and its intensity diminished due to the carrier leakage from the quantum well, in accordance with prediction. When the field exceeded a critical value, however, a new PL peak emerged unexpectedly, giving rise initially to a double peaked spectrum and subsequently dominating the initial peak. The appearance of the double peaked structure was found to be accompanied by a negative differential resistance in photocurrent measurement. These unusual phenomena are ascribed to the electric field-induced resonant coupling of the two lowest quantum levels in the adjacent quantum wells.
Switching of Microwave Energy by a Superconducting Polycrystalline BaPb1-xBixO3 Thin Film
Authors: Saeki Koshiro , Kubo Hideyuki , Takai Hiroyuki , Minami Kazuo
Published: November 2005

Superconducting polycrystalline BaPb1-x
Bi
x
O3 thin film is attempted in the switching of microwave energy of 2.8 GHz. The film is installed in a TE111 mode cylindrical cavity made of copper and immersed in liquid helium. Transition from super- to normal-conducting states is made by a pulse current through the film of the order of 108 A/m2. The microwave energy stored in the cavity is extracted in the short time of 60 ns. The observed output powers are compared with numerical analysis and the possibility of improving the switching characteristics is discussed.
Photon Collection Enhancement by White Rear Cover Reflection and the Design of Reference Cells for Module Performance Measurement
Authors: Shimokawa Ryuichi , Nagamine Fumiaki , Hayashi Yutaka
Published: November 2005

The effect of rear cover sheet reflection in solar modules on cell performance was investigated by shading and LBIC techniques. It was found that the photon collection enhancement was caused by the light reflection on the white rear cover sheet (white Tedlar) and 12–13% of the incident photons on the white rear cover sheet were guided to the cell by total internal reflection. Also, it was confirmed from the spectral response measurement that a single cell package without surrounding cells and white rear cover sheet could be used as a reference cell for the evaluation of solar module performance.
MO VPE (Al, Ga)As/GaAs 870 nm Oxide Stripe Lasers with Highly Uniform Laser Characteristics
Authors: Druminski M. , Gessner R. , Kappeler F. , Westermeier H. , Wolf H.-D , Zschauer K.-H.
Published: November 2005

The excellent quality and uniformity of MO VPE-grown (Al, Ga)As heterostructures for laser diodes is demonstrated by results on narrow oxide stripe lasers (λ=870 nm). The high uniformity over the substrate area is characterized by a low scatter of significant laser parameters. The low interface roughness in MO VPE heterostructure layers facilitates good laser performance up to high pulsed power levels. The characteristic temperature ranges from 180 to 220 K which allows CW lasing operation at heat sink temperatures of up to more than 100°C even for junction-up mounted lasers. Degradation rates as low as 1×10-5 h -1 at 100°C and 5 mW optical output/facet have been measured over operating times exceeding now 16000 h.
Soft-X-Ray Emission from 1 µm Laser-Irradiated Cannonball Target
Authors: Kitagawa Yoneyoshi , Matsunaga Hirohide , Shiraga Hiroyuki , Yamanaka Chiyoe
Published: November 2005

We observed 0.2–1.56 keV X-ray radiant spectra from 1.052 µm laser-irradiated cannonball and glass microballoon targets using a seven-channel X-ray diode array. The Au-coated cannonball and a laser pulse of 500 ps increased the radiation to a level more closely approaching Planck radiation than did the glass microballoon and a 100 ps laser pulse. Increasing laser intensity decreased the radiation conversion efficiency. The tamper- and cavity-plasma opacity to the radiation is also discussed.
Observations of Time-Dependent Asymmetric Spectra of Density Fluctuations in a Linear Turbulently Heated Plasma by Far-Infrared Laser Scattering
Authors: Nagatsu Masaaki , Yamamoto Masahiro , Nishida Ikuo , Inuzuka Hiroshi , Tsukishima Takashige , Mizuno Koji
Published: November 2005

Time-dependent asymmetric spectra of the density fluctuations in a linear turbulently heated plasma are measured by far-infrared laser scattering using a newly developed dual homodyne detection system. The low frequency ( < 25 MHz) density fluctuations are found to propagate toward the axis of the cylindrical plasma initially. However, only those propagating outward are observed at a later time. The frequency spectra for various wavenumbers are also shown.
Effect of Carbon Concentration on Thermal Conversion in Semi-Insulating GaAs
Authors: Obokata Takeshi , Okada Hideo , Katsumata Tooru , Fukuda Tsuguo
Published: November 2005

A systematic analysis of heat treatment experiments on a large number of melt-grown GaAs crystals with different concentrations of carbon revealed that the carbon concentration strongly affects thermal conversion. That is, the crystal with a higher concentration, larger than 1.5×1016 cm-3, showed a greater tendency to convert during the 20 min anneal at 850°C with a Si3N4 cap than the crystal with a concentration of carbon less than 1.5×1016 cm-3. This is further evidence of outdiffusion of the main electron trap, EL2, during the anneal.
Transient Change in the Velocity Distribution Functions of Sputtered Atoms during Initial Dose in Ion-Beam Bombardment
Authors: Matsuda Yoshinobu , Honda Chikahisa , Matsubaguchi Satoshi , Moroishi Tadamasa , Muraoka Katsunori , Maeda Mitsuo , Akazaki Masanori
Published: November 2005

Velocity distribution functions of sputtered iron-atoms under argon-ion bombardment were directly measured with a rapid-frequency-scan dye laser. Each measured profile was fitted with the Thompson formula, and an equivalent surface binding energy was estimated at each ion dose. The surface binding energy thus obtained was near the formation energy of iron in iron oxides at a low ion dose (less than 1×1019 ions/m2), but approached the sublimation energy of a pure iron above 5×1019 ions/m2.
The Role of Hydrogen Radicals in the Growth of a-Si and Related Alloys
Authors: Oda Shunri , Ishihara Shun'ichi , Shibata Naoki , Shirai Hajime , Miyauchi Akihiro , Fukuda Kaichi , Tanabe Akihito , Ohtoshi Hirokazu , Hanna Jun'ichi , Shimizu Isamu
Published: November 2005

A new method of the preparation of a-Si and its alloys is proposed. The role of atomic hydrogen in the growth of a-Si:H:(F) films by the glow-discharge of a mixture of SiF4 and H2 is clarified. Amorphous Si:H:(F) films have been prepared in a plasma-free environment by employing long-lifetime radicals, i.e., atomic hydrogen and SiF
n
radicals. Highly photoconductive a-Si:H:(F) films and related alloys, viz. a-SiGe
x
:H:(F) and a-SiC
x
:H:(F), have been obtained at high deposition rates with the result that each radical is controlled independently.
Shallow and Deep Donor Levels in S-Doped Ga0.52In0.48P Grown by Chloride VPE
Authors: Kitahara Kuninori , Hoshino Masataka , Kodama Kunihiko , Ozeki Masashi
Published: November 2005

Electrical properties were studied for S-doped Ga0.52In0.48P grown by chloride vapor-phase epitaxy over a wide carrier concentration ranging 1×1015–4×1018 cm-3 using Hall effect measurements. Persistent Photoconductivity caused by the deep level was observed, and was used for an approximate estimation of the deep donor concentration. It was deduced that some of the doped donor atoms form the deep level. The ionization energies of shallow and deep-donor levels were estimated from temperature dependence of carrier concentrations.
Observation of Room Temperature Excitons in GaSb–AlGaSb Multi-Quantum Wells
Authors: Miyazawa Takeo , Tarucha Seigo , Ohmori Yutaka , Suzuki Yoshifumi , Okamoto Hiroshi
Published: November 2005

Absorption peaks due to excitons in GaSb (7 nm)–Al0.25Ga0.75Sb (3 nm) multi-quantum-wells (MQW) were first observed at room temperature. The absorption spectrum exhibited a double-peak structure. The shorter wavelength and the longer wavelength peaks were assigned to be n=1 light hole and heavy hole excitons, respectively, based on a study of the polarization dependence of the guided spontaneous emission of an MQW laser diode. Measurement of asymmetric X-ray double crystal diffraction showed that negligible strain was induced in the GaSb quantum wells grown on GaSb substrate. This result implies that the hole band reversal observed by other authors using the MQW grown on a lattice-mismatched GaAs substrate rarely occurs in GaSb quantum wells grown on a GaSb substrate. The electric field effect on the exciton absorption is also presented.
Study on the Nature of Extrinsic Scattering Centers in Fluoride Glass Optical Fibers
Authors: Kanamori Terutoshi , Hattori Hideo , Sakaguchi Shigeki , Ohishi Yasutake
Published: November 2005

The origin and loss characteristics of extrinsic scattering centers in ZrF4-based fluoride optical fibers have been investigated. Scattering centers larger than about 1 µm have been found to be micro-crystallites, inclusions of impurity particles or bubbles. They can be reduced by improving the preform-preparation conditions. For scattering centers of submicron size, scattering loss has been estimated at wavelengths of 0.633 and 2.55 µm and has been indicated to exhibit wavelength dependence of λ-2. Loss factors for a fiber fabricated under improved preform-preparation conditions have been analyzed. A minimum loss of 3.0 dB/km at a wavelength of 2.55 µm was proved to arise from about 2 dB/km of scattering and about 1 dB/km of absorption.