bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulator Experiments on Josephson Junction Harmonic Mixers
Authors: Ohmae Yoshinobu , Kubo Kenji , Kita Sadamu , Fujisawa Kazuo
Published: November 2005

We have studied the JJ harmonic mixing with an analog simulator devised by Magerlein. For even-harmonic mixing, there are two operation modes: zero-bias operation and finite-bias operation. The former is peculiar to even-harmonic mixing, while the latter is common to both even- and odd-harmonic mixing. Zero-bias operation is possible with a supply of LO current that suppresses the zero-voltage step completely, and it has the advantage of eliminating the dc bias supply and its accompanying heating effect and shot noise. For relatively low LO frequency (\varOmegaLO≃0.6), zero-bias operation has a higher conversion efficiency than does finite-bias operation. 2nd harmonic mixing under zero-bias operation has a conversion efficiency nearly equal to the fundamental mixing in the range \varOmegaS\lesssim0.5.
Electrical Conduction of Nylon 6 at High Temperature
Authors: Nakamura Shuhei , Sawa Goro , Ieda Masayuki
Published: November 2005

The step-response current i(t) of nylon 6 is described in detail in the time range 5–3600 s at temperatures from 80–120°C with applied fields of about 5×103 to 5×105 V/cm. The log
i(t)-log
t curve can be expressed by three straight lines and the current consists of an absorption component and an approximately constant one, the latter of which is assumed to be the quasi-steady state conduction current. The absorption current changes in its functional parameters with applied field. The total absorption charge tends to saturate with rising temperature or applied field, and is almost independent of the electrode metal. These results can be interpreted in terms of the immigration of a fixed number of ions existing in the polymer toward the counter electrode. It is also suggested from the ohmic nature of the quasi-steady conduction current that the accumulated ions do not establish a space charge but are neutralized at the electrode.
High-Energy Neutral Atoms in the Sputtering of ZnO
Authors: Tominaga Kikuo , Ueshiba Nozomu , Shintani Yoshihiro , Tada Osamu
Published: November 2005

Dips were observed in the distribution curves of the deposition rates of ZnO films prepared both by planar diode and by planar magnetron sputtering. These dips are ascribed to high-energy neutral atoms bombarding the films. The influence of high-energy neutral atoms on the mixed orientation of ZnO film is also investigated in planar diode sputtering. In planar magnetron sputtering, which gives highly [00·2] oriented ZnO films, the correlation between the degree of c-axis orientation and the flux of high-energy neutral atoms is examined. It is found that high-energy neutral atoms should be considered when trying to obtain highly-oriented ZnO films.
Interface Structure of P-Type GaP/Au/Au-Zn
Authors: Komatsu Shuichi , Nakahashi Masako , Koike Yoshiyasu
Published: November 2005

Studies on the microstructure of the GaP/Au/Au-Zn system were carried out with an electron microscope and X-ray energy spectrometer. It was shown that an AuGa layer was formed at the interface between GaP and the Au/Au-Zn layer, and that the AuGa reaction layer contained Zn atoms. It is considered that the AuGa layer may contribute to the mechanical strength of the deposit layer for wire bonding and reliable ohmic contact for a P-type GaP. The Au underlayer seems to promote the formation of the AuGa layer, which starts forming at 490°C.
Growth of Bismuth Layers on Si(100) Surfaces
Authors: Kawazu Akira , Otsuki Tatsuo , Tominaga Goroh
Published: November 2005

The adsorption of bismuth on Si(100) surfaces is studied by quadrupole mass spectrometry, LEED and AES. Two adsorption states are observed: one is a two-dimensional (first) phase with saturation coverage and the other a bulk-like (second) phase without saturation coverage. When the two-dimensional phase of Bi was formed at a high substrate temperature, the LEED patterns from the Si surfaces showed an Si(100)2×1 structure with weak fractional order spots. In the Auger amplitude vs. deposition time curves, break points were observed at the completion of the first-phase adsorption. These points shift towards the higher coverage side with decreasing substrate temperature during deposition in accordance with the increase in the amount of adsorbed bismuth atoms.
Computer Simulation of Pulse-Type Photocurrent Oscillations in CdIn2S4 Single Crystals
Authors: Seki Yasukazu
Published: November 2005

Computer simulation of the low-frequency oscillatory photocurrent trace in CdIn2S4 single crystals was carried out by the Runge-Kutta method. The simultaneous equations proposed took into account the thermal quenching process. i.e., the electron lifetime τ was assumed as a suitable step function for the calculation on the basis of experimental results. The oscillatory waveform and the frequency vs. applied electric field were given by the experimental results. It is shown by the simulation that the thermal quenching process plays an important role in this oscillation.
Coloration Process in Solid-State Electrochromic Device
Authors: Shizukuishi Makoto , Shimizu Isamu , Inoue Eiichi
Published: November 2005

Measurements of the transient shape of an electric current were carried out to obtain information about the coloration mechanism in an amorphous WO3(a-WO3) solid-state electrochromic device (ECD). The time dependence of the current was classified into three regions.
(1) The absorption current associated with the dielectric relaxation of the oxide layers and the subsequent injection current from the electrodes to the bulk.
(2) The current caused by the electrochemical reaction (coloration) at the interface between the a-WO3 and the dielectrics.
(3) The current modulated by the electromotive force arising from the colored species in both a-WO3 and dielectrics.
The coloration process in this solid-state ECD was investigated in connection with the response speed using kinetic analysis.
Current Transport Mechanism of Hydrogenated Amorphous Silicon Schottky Barrier Diodes
Authors: Mishima Yasuyoshi , Hirose Masataka , Osaka Yukio
Published: November 2005

We report detailed studies on the forward current-voltage characteristics of Pd/a-Si:H Schottky barrier diodes. Exact values of the barrier height and its temperature coefficient have been determined by the internal photoemission technique. Based upon this result, the current transport mechanism through the a-Si:H Schottky barrier has been quantitatively examined. The fundamental characteristics of the Schottky barrier are considered to be dominated by diffusion theory rather than by thermionic emission theory.
Zn Diffusion into AlGaAsSb and Its Application to APD's
Authors: Kagawa Toshiaki , Motosugi George
Published: November 2005

Vapor-phase Zn diffusion into n-type GaSb and AlGaAsSb at temperatures of 500°C–540°C with Zn-Sb and Zn-As compounds as diffusion sources was studied. Zn diffusion was carried out with good reproducibility and flat diffusion fronts were obtained. Zn-diffused AlGaAsSb APD's were fabricated and small dark currents were obtained compared with those of our previously-reported grown junction APD's.
Effect of Crystallinity on Electrical Conduction in Polypropylene
Authors: Ikezaki Kazuo , Kaneko Takanobu , Sakakibara Toshio
Published: November 2005

The electrical conduction of 20 µm thick polypropylene films with different crystallinities has been studied at 72°C below 400 kV/cm. The field dependence of the current shows that the conduction mechanism in this polymer is ion hopping. The estimated ionic jump distance strongly depends on the polymer crystallinity, and it decreases from 100 Å to 45 Å as the crystallinity increases from 50.5% to 78%. Preheating of samples seriously affects the electrical conduction in polypropylene, so differences in conductivity, activation energy and jump distance obtained by different authors can be explained partly by differences in the thermal history of the samples used.
Effect of Molecular Weight on Phase Transition of Polyethylene under High Pressure
Authors: Hikosaka Masamichi
Published: November 2005

The effect of the molecular weight distribution which makes polyethylene (PE) behave as a multi-component system in the phase transition under high pressure suggested by the authors from thermal study was confirmed by an X-ray method. Fractionated PE crystallized into an extended-chain crystal (ECC) showed the equilibrium successive first-order phase transition of a one-component system. But a PE mixture of two different molecular weights or unfractionated PE crystallized into ECC showed continuous melting of hexagonal solid characteristic of the melting of binary or multi-component systems. PE crystallized into folded-chain crystal (FCC), on the other hand, showed no equilibrium transition. These results confirm our previous suggestion and it is concluded that only monodisperse ECC-PE can be regarded as a thermodynamically pure material.
Effect of High Pressure on the Order-Disorder Transition in CuPt
Authors: Ichikawa Masashi , Iwasaki Hiroshi , Endo Shoichi
Published: November 2005

The order-disorder transition temperature T

c
of the alloy CuPt has been determined at pressures up to 80 kbar by the electrical resistance measurement technique. T

c

decreases almost linearly with increasing pressure at a rate of -0.9±0.1°C/kbar, making a striking contrast to the behaviors of the other ordering alloys hitherto studied. The observed pressure dependence of T

c
has suggested the existence of a high pressure modification, but an extended investigation including X-ray diffraction analysis on pressurized and quenched samples has shown that the L11-type ordered structure remains stable at least up to 120 kbar.
Secondary Electron Emission from Al, Cu, Ag and Au Metal Targets under Proton Bombardment
Authors: Koyama Akio , Shikata Takashi , Sakairi Hideo
Published: November 2005

The secondary electron emission coefficients, γ, forin-situvacuum-deposited targets of Al, Cu, Ag and Au are measured under proton bombardment in the energy range 4–12 MeV at a pressure of 1–2×10-8Torr. The values of γ for Al are only half of those obtained experimentally by Aarsetet al.The ratios between γ and the electronic stopping powers for protons in these four materials are independent of the incident energy. The values of the ratios are almost equal to those reported by Baragiolaet al.for the same target materials in the much lower energy region below 50 keV. The ratio for Al is theoretically calculated. The theoretical ratio is also independent of the incident energy, but is only half of the experimental one.
Optical Spectroscopy in Reactive Sputter Etching and Its Application to Process Control
Authors: Oshima Masaharu
Published: November 2005

Optical emission spectra in the reactive sputter etching (RSE) of Si, SiO2 and Si3N4 have been investigated using a spectrometer with a collimating system. Emission lines of Si, F, CN and N2 reflecting the reaction products in the RSE of Si3N4 were observed. From the dependence of these lines on the etching conditions, the active species in RSE was found to be not F radicals, but CF
x
ions. The applicability of these lines for use as the end point monitor was also investigated. In addition, the plasma gas temperature was determined by rotational analysis of plasma etching and RSE in C2F6 gas mixed with O2 or C2H4 gas.
Quantitative Analysis of Small-Angle X-Ray Scattering of Bone: Determination of Sizes of Its Collagen and Apatite Components
Authors: Matsushima Norio , Akiyama Morio , Terayama Yoshio
Published: November 2005

The diffuse anisotropy scattering from oriented bone sections is quantitatively studied on the basis of recent developments in small-angle X-ray scattering (SAXS). This SAXS from the bone is explained as a random distribution of apatite rods with a preferred orientation of the principal axis of the rods parallel to the longitudinal axis of the bone. The results obtained suggest that the average cross-sections of the apatite rods and the collagen components are 40–55 A and 75–105 A, respectively, which indicates that the apatite rods are within the collagen fibrils.
Thermally Stimulated Exoelectron Emission in KCl: Tl, KCl: Cu and Undoped KCl
Authors: Kamada Masao , Furukawa Katsuki , Tsutsumi Kenjiro
Published: November 2005

Thermally stimulated exoelectron emission (TSEE) in KCl: Tl, KCl: Cu and undoped KCl cleaved in a clean high vacuum and X-rayed at liquid nitrogen temperature, is measured simultaneously with thermoluminescence (TL). On the basis of F-light stimulation experiments and close correlations between TSEE and TL, the main TSEE glow peaks are ascribed to the thermal annihilation of color centers. Among these, the TSEE glow peak at about 210 K in KCl: Tl and KCl: Cu is ascribed to the diffusion of VK centers and the subsequent reaction of these centers with electron-excess centers such as F' centers, while the TSEE glow peak at 207 K in undoped KCl is due to the thermal release of electrons from F' centers. The mechanism of the exoelectron emission due to the annihilation of VK centers may be interpreted in terms of a kind of Auger effect.
Effect of Oxygen and Hydrogen on Transient Photocurrents in Evaporated Thin Films of β-Copperphthalocyanine
Authors: Mizuguchi Jin
Published: November 2005

Transient photocurrents in evaporated thin films of β-copperphthalocyanine in atmospheres of oxygen and hydrogen at 120°C have been investigated in the near ultraviolet and visible regions. The change of dark conductivity in these ambients is in agreement with the reported observation that oxygen and hydrogen increase and decrease the dark conductivity respectively. An anomaly in photoconductivity was observed, however, in that the photoconductivity decreased in oxygen and increased in hydrogen, whereas the opposite effect is usually observed. The decrease in photocurrent in oxygen is caused by thermally-assisted photodesorption, annihilating holes: O2
-(ads)+hole \stackrelh
v→O2 (gas). The increase in photoconductivity in hydrogen is interpreted in terms of an adsorption scheme whereby hydrogen removes electron traps, causing both types of photocarrier to contribute to the photocurrents.
DC Drift Phenomena in LiNbO3 Optical Waveguide Devices
Authors: Yamada Syoji , Minakata Makoto
Published: November 2005

DC drift phenomena in LiNbO3 optical waveguide devices are investigated. From low speed switching experiments of a directional coupler modulator, two kinds of dc drift are found to exist in this device. One is a short time dc drift with several seconds relaxation time and the other is a long time one whose relaxation time is several hours. It is shown analytically that the former originates from current leakage through a buffer layer, and it is successfully suppressed by a separation of the layer. For the latter problem, photocurrents measuring experiments were carried out for various LiNbO3 samples. We may consider from the results that the main origin of the long time dc drift is a photorefractive effect due to the guided light itself. Some solutions for overcoming these effects are also given.
Retardation of Sb Diffusion in Si during Thermal Oxidation
Authors: Mizuo Shoichi , Higuchi Hisayuki
Published: November 2005

Investigation of Sb diffusion in Si during thermal oxidation using LOCOS (LOCal Oxidation of Silicon) shows that diffusion of Sb in Si is retarded during thermal oxidation. This suggests that the diffusion mechanism of Sb differs from those of B and P, which diffuse faster during thermal oxidation. A model which can explain both enhanced and retarded diffusion of impurities in Si during oxidation is proposed. The model assumes that B and P diffuse only by interstitials, Sb diffuses only by vacancies and As diffuses by both vacancies and interstitials.
Analysis of Electron Beam Induced Current Considering Sample Dimensions–Measurement of Diffusion Length and Surface Recombination Velocity–
Authors: Fuyuki Takashi , Matsunami Hiroyuki
Published: November 2005

The electron beam induced current (EBIC) in a sample was analyzed, taking the sample dimensions into account. The minority carrier distribution is greatly affected by the length w between a potential barrier and an ohmic contact, if w is equal to or smaller than one diffusion length. The EBIC was calculated by a simple method using an image source-and-sink distribution. For L<w, the logarithm of EBIC J decreases linearly in the middle range of the scanning distance x. The value of L estimated from the slope of the log
J vs. x curve is much shorter than the real diffusion length. L must be determined by considering the influences of ohmic contact and surface recombination. If L is greater than w, the slope of the curve in the linear region does not change even if L varies. Therefore, L cannot be determined definitely from the slope of the curve. Experimental results in Si Schottky diodes showed good agreement with the theory.
Temporal Evolutions of Electron Temperature and Density of Turbulently-Heated Tokamak Plasmas in TRIAM-1
Authors: Hiraki Naoji , Nakamura Kazuo , Nakamura Yukio , Itoh Satoshi
Published: November 2005

The temporal evolutions of the electron temperature and density are measured in a turbulent heating experiment in TRIAM-1. Skin-like profiles of the electron temperature and density are clearly observed.
The anomality in the electrical resistivity of the plasma in this skin-layer is estimated, and the plasma heating in this skin-layer is regarded as being due to anomalous joule heating arising from this anomalous resistivity.
The ratio of drift velocity to electron thermal velocity in the layer is also calculated, and it is shown that the conditions needed to make the current-driven ion-acoustic instability triggerable are satisfied.
Evaluation of Relative Permittivity and Electrical Conductivity of Ion-Exchange Beads by Analysis of High-Frequency Dielectric Relaxations
Authors: Ishikawa Akira , Hanai Tetsuya , Koizumi Naokazu
Published: November 2005

Dielectric measurements on suspensions of an ion-exchange resin, Sephadex G-25, in water, were carried out over the frequency range 30 Hz to 1.7 MHz. The marked dielectric relaxations observed were assigned to interfacial polarization. To evaluate the relative permittivity and electrical conductivity of the dispersed resin beads from the dielectric relaxation data, the observed data were analysed on the basis of two theoretical equations: one proposed by Wagner for dilute disperse systems, and the other derived by Hanai for concentrated disperse systems. The results of this data analysis showed that more suitable values for the relative permittivity and electrical conductivity of the beads in suspension were obtained from Hanai's equations.
Surface Potential Decay in Polyethylene
Authors: Mizutani Teruyoshi , Oomura Tetsurou , Ieda Masayuki
Published: November 2005

Both thermally-stimulated and isothermal surface potential decay have been investigated in both high- and low-density polyethylene (HD-PE and LD-PE) charged by two different methods, i.e. corona- and DC potential-chargings. A clear cross-over phenomenon was observed for the V
s-T characteristics in HD-PE, but not for LD-PE. Similar decay characteristics were obtained for corona- and DC potential-charging.
Estimation of the amount of space charge in the DC potential-charged polyethylene gave direct evidence for the charging-potential-dependent occupancies of deep surface states and shallow bulk ones. The ratio of surface charge to bulk space charge for HD-PE decreased rapidly with the charging potential, while most charges were still in the surface states for LD-PE charged at 2000 V. This is why a clear cross-over appears in HD-PE.
Transient Current Peak on Plasticized Polyvinylchloride Containing Absorbed Water
Authors: Onoda Mitsuyoshi , Nakayama Hiroshi , Amakawa Kiyoshi
Published: November 2005

The mechanisms of the current peak observed in the current-time characteristics on plasticized polyvinylchloride containing absorbed water have been investigated. The results suggest that this peak is associated with the injection of protons released due to an anode-oxidation reaction. The apparent mobility has been roughly estimated to be about 3–5×10-9 cm2/V·s for protons at 80°C.
Thermally Stimulated Current in Polyacetylene
Authors: Yoshino Katsumi , Sakai Toshihiko , Yamamoto Yoshihiro , Inuishi Yoshio
Published: November 2005

Trap depths were estimated as 0.06 eV in pristine polyacetylene, 0.10 eV in oxygen-doped polyacetylene and 0.20, 0.55 eV in γ-ray-irradiated polyacetylene from thermally stimulated current measurements.
Self-Healing Breakdown at Spherulite Boundaries of Polyethylene Thin Films
Authors: Kitagawa Keiichi , Sawa Goro , Ieda Masayuki
Published: November 2005

A polyethylene (PE) thin film consisting of two-dimensional spherulites of thickness 0.7–1.4 µm are prepared with heat treatment of a solution-grown film. Most breakdown measurements are made on the Al(top)-PE-Al(base) systems with ramp voltages at rising speeds of 102, 104 and 106 V s-1 at room temperature. Breakdown occurs mostly at the boundaries between the spherulites. At 106 V s-1 the electric strength when the top electrode is a cathode and is smaller than that in the base cathode case, while at 102 V s-1 they are nearly identical irrespective of the polarity. In the base cathode case, the rising speed of 106 V s-1 yields a larger electric strength than that of 102 V s-1. These results are interpreted in terms of roughness of the top surface and space charge formation. The results on the Au-PE-Al and Al-PE-Au systems are also consistent with the above interpretation. Decay of the space charges are also discussed.
Emission Distributions from NEA Cold Cathodes
Authors: Hatanaka Yoshinori , Sukegawa Tokuzo , Ando Takao
Published: November 2005

The distributions of the electron current emitted from NEA cold cathodes were measured by dissecting the electron optical image with a 5 µm diameter pin-hole attached to a metallic target in an experimental tube similar to a 1-inch-vidicon. Then the distributions of emission current density were displayed threedimensionally on an oscilloscope. The NEA cold cathode was constructed by shallow diffusion of Zn into the n-GaAsP substrate followed by deposition of a ring-shaped contact electrode on the diffused layer. It was found that the current distributions emitted from an NEA cold cathode nearly agree with Kohn's theory. A Gap cold cathode designed to reduce current crowding was also examined and it was demonstrated that the emission current could be concentrated at the center of the cathode at a moderately large diode current.
Dielectric Properties of Bi4Ti3O12 below the Curie Temperature
Authors: Ehara Shaw , Muramatsu Kunitaka , Shimazu Masaji , Tanaka Junzo , Tsukioka Masashi , Mori Yasumichi , Hattori Takeshi , Tamura Hiroshi
Published: November 2005

The dielectric permittivity, optical transmission spectrum and temperature dependence of resistance were investigated in single crystals of Bi4Ti3O12 and BaBi4Ti4O15. It is found that the dielectric anomalies previously reported below the Curie temperature are due electron space charges of inhomogeneous distribution in the material and near the non-ohmic electrodes.
Formation of Thick, Thermally-Stable High-Resistivity-Layers in GaAs by Oxygen Ion Implantation
Authors: Asano Tanemasa , Atanassov Rosen D. , Ishiwara Hiroshi , Furukawa Seijiro
Published: November 2005

The channeling implantation of oxygen into n-type GaAs has been studied in order to form thick and thermally stable high-resistivity-layers. Carrier removal profiles and deep trapping levels are measured by the C-V and DLTS techniques in both oxygen- and proton-implanted layers. The C-V measurements show that the carrier removal by oxygen implantation is stable at least up to 800°C, and the DLTS measurements show that two trap levels exist in oxygen-implanted layers after annealing at 800°C while only one level is observable in unimplanted and proton-implanted layers. It is demonstrated that the carrier removal depth by the oxygen channeling implantation is about twice as deep as that by conventional random implantation.
Effects of Tailing of Density of State on the Mobility of Si-MOSFETs at Low Temperatures–A Proposal for the Method of Characterization of Si-SiO2 Interfaces–
Authors: Yagi Atsuo , Kawaji Shinji
Published: November 2005

An attempt is made to explain the electron mobility of silicon MOSFETs in low electron desities at low temperatures by taking account of the phenomenological change in the electrostatic screening due to smearing of the two-dimensional subband tail. The results of application of this approach to various samples are satisfactory for characterizing the electrical properties of Si-SiO2 interfaces in silicon MOS devices.
Deep Trap States in Si3N4 Layer on Si Substrate
Authors: Fujita Shizuo , Nishihara Michinori , Hoi Won-Lon , Sasaki Akio
Published: November 2005

Charge transfer processes in metal-nitride-semiconductor (MNS) diodes are investigated. The spatial and energetic distributions of the trap state density in Si3N4 layers on Si substrates are determined by measuring the amount of transferred charge in MNS diodes. We apply to MNS diodes relatively wide and low-pulsed voltages so that trap states spatially distributed deep in the Si3N4 layer can be examined, and we analyze the electronic properties of the trap states without any pre-assumptions as made in past analyses. The results show that (i) charging and discharging processes are mainly due to direct tunneling of electrons, (ii) donor-like trap states lie near the mid-gap of the Si3N4 layer on an Si substrate, (iii) they are distributed uniformly in the region of 26–44 Å from the Si/Si3N4 interface, and (iv) their density is 3×1019 cm-3.
Measurement of Wave-Number Spectrum Parameters of Ion Wave Turbulence by the Probe-Pair Method
Authors: Ohba Yasuo , Iwama Naofumi , Tsukishima Takashige
Published: November 2005

A fixed probe-pair method proposed by the authors for estimating the wave-number spectral moments of fluctuations is applied to current-driven ion wave turbulence developed in a positive mercury column. Analog and digital processing of the fluctuation signals sensed by two fixed Langmuir probes is carried out, and good agreement is obtained between them. A frequency-based relay correlator is used for the analog processing. The mean wavenumber and the wavenumber spectral width parallel and perpendicular to the direction of the electron drift are obtained as functions of frequency. The results obtained by the present method are consistent with those obtained by the microwave scattering method.
Internal Bias Field Effects in Lead Zirconate-Titanate Ceramics Doped with Multiple Impurities
Authors: Takahashi Sadayuki
Published: November 2005

The effects of doping with multiple impurities on the electromechanical properties of lead zirconate-titanate ceramics have been investigated from the viewpoint of the internal bias field. The internal bias field is strengthened by doping with the multiple acceptors K and Fe, but weakened by the multiple donors La and Nb. Simultaneous doping with donor and acceptor prevents the field from being enhanced by the latter. These facts suggest that the internal bias field is caused by a complex of an acceptor impurity and an oxygen vacancy. The properties of ceramics can be varied by controlling this field, and the mechanical quality factor and the aging change in the frequency constant are proportional to it.
Studies on Some Properties of Singlet-Ground-State Compounds and Alloys of Praseodymium
Authors: Sugawara Tadashi , Terui Kenji , Takayanagi Shigeru
Published: November 2005

Measurements were made of the electrical resistivity, thermal conductivity and mechanical strength of singlet-ground-state compounds of Pr; PrCu6, PrNi5, PrPt5 and PrIn3, in connection with their use for nuclear refrigeration. The composition dependences of these quantities were also studied in nonstoichiometric alloys of these materials. It was found that, except for Pr-Ni alloys, alloys containing partner metals in excess of stoichiometry has larger conductivity and mechanical strength than the stoichiometric compounds. In Pr-Ni alloys with compositions close to PrNi5, an anomalous behavior of conductivities was observed at low temperatures. Using these results, the advantages and disadvantages of the above compounds and alloys as nuclear refrigerants are discussed from the technical viewpoint.
Thermal Decomposition of Methanol behind Shock Waves
Authors: Tsuboi Takao , Katoh Masataka , Kikuchi Shigeru , Hashimoto Kazunobu
Published: November 2005

The thermal decomposition of methanol in argon behind incident and reflected shock waves is studied. The reaction was followed by ultraviolet (UV) absorption between 1900 and 2200 Å and by infrared (IR) emission of methanol at wavelengths 2.4–2.9 µm, 3.1–3.9 µm and 4.8–5.2 µm and of formed species at wavelengths 2.7 µm, 3.6 µm and 4.9 µm. The temperature and the density dependences of the decomposition rate constants were observed at temperatures from 1500 to 1900 K, at total densities from 10-5to 2×10-4mol/cm3and at concentrations from 0.01% to 1.0% methanol. The experimentally-determined signals are compared with the calculated values and the density-dependent rate constants of the unimolecular reaction of methanol are obtained.
Experimental Study of Josephson Junction 2nd-Harmonic Mixers at 70 GHz
Authors: Kita Sadamu , Fujisawa Kazuo
Published: November 2005

Josephson junction (JJ) harmonic mixers with even-harmonic numbers can operate at zero bias voltage. Among them, low harmonic ones are expected to have a good conversion efficiency. Hence, we have done experiments on the 2nd-harmonic mixer at 70 GHz. It is found that mixing behaviors are classified into three types: zero-bias, finite-bias and intermediate operation. It is also found that the conversion efficiency of the 2nd-harmonic mixer is not so much less than that of the fundamental mixer. We obtained a conversion gain of +1.5 dB with the 2nd-harmonic mixer, and +2.0 dB with the fundamental mixer.
Schottky-Barrier Properties of Nearly-Ideal (n ≃1) Al Contacts on MBE- and Heat Cleaned-GaAs Surfaces
Authors: Sakaki Hiroyuki , Sekiguchi Yoshinobu , Sun Dian Chao , Taniguchi Mitsuhiro , Ohno Hideo , Tanaka Akihiro
Published: November 2005

Aluminum films were deposited in ultra-high vacuum onto heat-cleaned-surfaces as well as oxygen-free MBE surfaces of (100) GaAs to form Schottky barriers with and without intervening oxide layers. The measured ideality factor n was close to unity (n≃1.02∼1.10) irrespective of the oxide thickness t
ox, indicating the transport being dominated by thermionic emission processes. In contrast, the barrier height decreased systematically from 0.89 eV to 0.67 eV, as t
ox is reduced, suggesting the presence of negatively charged centers (≃1012/cm2) at GaAs/oxide interfaces.
Radiation Annealing of GaAs Implanted with Si
Authors: Arai Michio , Nishiyama Kazuo , Watanabe Naozo
Published: November 2005

The use of radiation from halogen lamps to anneal implanted GaAs has been studied. Semi-insulating GaAs wafers implanted with 3×1012 cm-2 silicon at 70 keV were completely activated by 5 seconds rediation with or without encapsulation. The wafer temperature reached 950°C. This annealing method minimizes the thermal conversion of semi-insulating GaAs wafers.
Growth Conditions of Deposited Si Films in Solid Phase Epitaxy
Authors: Saitoh Shuichi , Sugii Toshihiro , Ishiwara Hiroshi , Furukawa Seijiro
Published: November 2005

Rutherford backscattering and channeling techniques have been employed to study growth conditions in the solid phase epitaxy of amorphous Si films deposited onto (100)Si substrates and annealed in a furnace. It has been shown that the epitaxial growth is inhibited in a surface region of about 100 nm thickness for samples exposed to air just after deposition, and that the growth can be successfully achieve up to the surface if deposited samples have been heated prior to air-exposure at temperatures higher than 200°C in the vacuum chamber. These results indicate that interconnected voids through which gases percolate are decreased by in situ heat treatment. It has also been shown that the crystalline quality of the epitaxial layers weakly depends on the deposition rate of amorphous films and the annealing conditions in the furnace.
Behavior of Fluorine Atoms in a-Si:F:H Alloy Investigated by Gas Evolution and Infrared Absorption
Authors: Sawada Akashi , Usui Setsuo , Kikuchi Makoto
Published: November 2005

Four a-Si:F:H alloys were prepared in SiF4/SiH4/Ar, SiF4/SiH4/H2, SiF4/H2/Ar and SiF4/H2 mixtures using an inductively-coupled glow discharge technique. A mass spectroscopic analyzer was used to observe gas evolution. In all films, a small amount of SiF4 gas evolved at 120°C, which is lower than the deposition temperature. At 300°C hydrogen evolved, just as has been reported in amorphous hydrogenated film. At 750°C a larger amount of SiF4 gas burst from the film. Infrared transmission results indicate that ≡SiF and =SiF2 in the film change into SiF4 when the film is annealed at a temperature higher than 400°C.
A New Inorganic Electron Resist Using Amorphous WO3 Film
Authors: Baba Mamoru , Ikeda Toshio
Published: November 2005

It was found that amorphous WO3 films become insoluble in alkaline solutions after electron-beam irradiation. Exposure characteristics show that threshold doses required for this effect increase with increasing incident electron energy and film thickness. The blue coloration simultaneously obtained by electron-beam irradiation is not directly responsible for the change in the solubility. This inorganic electron resist has some advantageous features in resolution, contrast, resistance to heat and acid, and ease of the processing.
Twin Tori for a New Bundle Divertor
Authors: Ikuta Kazunari
Published: November 2005

A new bundle divertor system using the straight stagnation axis in toroidal field together with the uniform field along the axis is discussed in detail. We call this type of divertor the “muffler divertor” because of its shape.
Enhanced Glide of Dislocations in GaAs Single Crystals by Electron Beam Irradiation
Authors: Maeda Koji , Takeuchi Shin
Published: November 2005

Influence of 30 keV electron beam irradiation on the mobility of α-dislocations in n-GaAs has been investigated at temperatures between 290 K and 470 K under a shear stress of 40 MN/m2 using a scanning electron microscope with cathodoluminescence mode. The effect of electron irradiation (0.39 A/m2) is equivalent to a temperature rise of 80–180 K in the testing temperature range, which is not explained by a heating effect of the lattice by the irradiation. The activation energy of the dislocation motion is decreased from 0.95 eV to ∼0.24 eV by the irradiation. The effect is explained in terms of recombination-enhanced glide of dislocations.
Boron Doping of Hydrogenated Silicon Thin Films
Authors: Matsuda Akihisa , Matsumura Mitsuo , Yamasaki Satoshi , Yamamoto Hideo , Imura Takeshi , Okushi Hideyo , Iizima Sigeru , Tanaka Kazunobu
Published: November 2005

Doping of boron into Si:H thin films by means of glow-discharge decomposition of SiH4 and B2H6 pre-mixed gas has been studied. Optical and electrical properties of these B-dopen Si:H films have been measured, and crucially discussed in relation to the contents of bonded H and incorporated B atoms in the specimens. A new deposition condition has been presented for obtaining “the p-type” film which has a wide optical gap amounting to 1.79 eV and dark conductivity exceeding 10-1 Ω-1cm-1.
Carrier Density Profiles in Zn- and Cd-Diffused InP
Authors: Ando Hiroaki , Susa Nobuhiko , Kanbe Hiroshi
Published: November 2005

This letter reports on studies of Zn and Cd diffusion in (100) n-InP single crystals, carried out using Zn3P2 and Cd3P2 sources. When n-InP background carrier density N
D is lower than 1016 cm-3, two diffusion fronts are observed and a p+-n--n junction is formed for Zn and Cd diffusion. A p+-n one-sided abrupt junction is formed when N
D is 1016–1017 cm-3. The carrier density profiles were observed through EBIC measurement, van der Pauw method, C-V measurement using a Schottky barrier contact, and diffusion velocity dependence on n-InP background carrier density.
Surface Lattice Constants of Si(111), Ni(111) and Cu(111)
Authors: Nakanishi Shigemitsu , Horiguchi Tetsuo
Published: November 2005

Surface lattice constants of Si(111), Ni(111) and Cu(111) were measured by the method using a critical reflection of electron beams along a crystal surface. All results obtained were in very good agreement (less than 0.3% difference) with the corresponding lattice constants of bulk crystals and revealed no evidence showing any expansion of surface nets as already reported by other workers on Si(111) surface.
Extremely High Mobility of Two-Dimensional Electron Gas in Selectively Doped GaAs/N-AlGaAs Heterojunction Structures Grown by MBE
Authors: Hiyamizu Satoshi , Mimura Takashi , Fujii Toshio , Nanbu Kazuo , Hashimoto Hisao
Published: November 2005

Selectively Si-doped GaAs/N-AlGaAs heterojunction structures have been grown by MBE. Two-dimensional electron gas accumulating at the interface of the heterojunction showed mobilities as high as 69,000 cm2/Vs at 77 K and 100,000 cm2/Vs at 4.2 K, with a sheet electron concentration of 5.5×1011 cm-2, which are higher than any reported so far. An enhancementmode high electron mobility transistor (E-HEMT), which was first fabricated from the heterojunction material, showed a field effect mobility of 49,300 cm2/Vs at 77 K, suggesting that this heterojunction material has potential for application to low-power, high-speed integrated circuits.
Frequency Dependence of the ac Josephson Effect in Nb Point Contacts in the Submillimeter-Wave Region
Authors: Noguchi Takashi , Morita Seizo , Imai Syozo , Takeuti Yosihisa , Mikoshiba Nobuo
Published: November 2005

We have measured the strength of the ac Josephson effect in Nb point contacts using an optically-pumped submillimeter-wave laser. We found that the frequency (i.e., corresponding step-voltage) dependence of the ac Josephson effect is clearly classified into three regions. In region I (V\lesssim1 mV) the voltage dependence is consistent with the prediction of the resistively-shunted junction model, while it is similar to the prediction of the frequency-dependent self-coupling theory in region II (1 mV\lesssimV\lesssimV
g (gap voltage)). In region III (V\gtrsim
V
g), we found an exponentially damping behavior with increasing voltage.
Thermal Expansion Multifilamentary Nb3Sn and V3Ga Superconductive Cables and Fiberglass-Epoxy and Cotton-Phenolic Composite Materials
Authors: Fujii G. , Ranney M. A. , Clark A. F.
Published: November 2005

The thermal contraction of multifilamentary Nb3Sn and V3Ga superconductive cables and the composite materials, fiberglass-epoxy and cotton-phenolic, was measured from room temperature to 4 K. Both the thermal contraction and the thermal expansion coefficient were tabulated as a function of temperature. The thermal contraction to 4 K of V3Ga was slightly greater than that of Nb3Sn. For the composites, thermal contraction to 4 K was 2.8 times higher transverse to the fibers than parallel to them.
Small Angle and Very-Small Angle X-Ray Scattering from Amorphous Pd80Si20 before and after Cold Work
Authors: Suzuki Carlos Kenichi , Doi Kenji , Kohra Kazutake
Published: November 2005

Structure of amorphous pd80Si20 and its change after 20% cold forging are examined by means of small angle scattering (SAS) and very-small angle scattering (VSAS) of X-rays. Before the cold work a hump is observed in SAS corresponding to a distance of 40 Å, and a broadening of transmitted beam is observed in the very-small angle region. The latter is shown not to be due to the refraction but really to the scattering of X-rays. The VSAS corresponds to the radius of gyration of 105 A. After cold work the SAS intensities diminish and the VSAS disappears.
Array of Distributed-Index Planar Micro-Lenses Prepared from Ion Exchange Technique
Authors: Oikawa Masahiro , Iga Kenichi , Sanada Takeshi , Yamamoto Noboru , Nishizawa Kouichi
Published: November 2005

A new class of arrayed distributed-index planar micro-lenses on a planar glass substrate has been monolithically fabricated. Each lens is with 1.2 mm in diameter and measured focal length is 9.4 mm. The minimum light spot which has been focused by the lens is as small as 17 µm which is almost limited by the diffraction. Clear images have been formed with a 5×5 lens array.
Anomalous Residual-Stress in Pulsed-Laser-Annealed Silicon-on-Sapphire Revealed by Raman Scattering
Authors: Yamazaki Ken-ichi , Yamada Masayoshi , Yamamoto Keiichi , Abe Kenji
Published: November 2005

Raman scattering measurements have been made in silicon-on-sapphire (SOS) annealed by irradiation of Q-switched ruby laser light. It is found that Raman signals from the optic mode show downward shifts of 4 to 5.5 cm-1 compared with the Raman shift in unstressed single crystal silicon, and that large tensile stress exists reaching 10–13.7 kbar in the recrystallized SOS. The origin of this anomalous stress is discussed on the basis of the laser annealing models that have been proposed to date.
Preparation of Preforms for Fluoride Glass Fibers
Authors: Mitachi Seiko , Shibata Shuichi , Manabe Toyotaka
Published: November 2005

Various dopants were added to 33BaF2-4GdF3-63ZrF4 (mol%) glass to control the refractive index and some properties of the resultant glasses were investigated. It has become apparent that LiF, PbF2, AlF3 and BiF3 are useful dopants for controlling the refractive index of BaF2-GdF3-ZrF4 glasses. Waveguide structure has been formed by casting a cladding glass melt around the core glass rod.
Gap and Subgap Structures of Niobium Observed by Radio Frequency Current Noise in Josephson Point Contact
Authors: Hayashi Yoshikazu , Kanayama Hiroshi , Kato Tatsuji , Ogawa Hideo
Published: November 2005

Superconducting gap structures of niobium modified by oxygen are observed by the enhancement of radio frequency noise in a Josephson point contact. Subgap structures of orders 4/5, 2/3, 3/5 and 1/2 are also observed. The values of gap voltage of the junction range from 2.49 mV to 1.85 mV due to modifications by interstitial oxygen in niobium. Josephson pair current may be responsible for the appearance of peaks of RF noise intensities.
Generation and Focussing of Intense Pulsed Light-Ion Beam at Nagaoka–ETIGO Project–
Authors: Masugata Katsumi , Nakayama Tadao , Inazumi Yoshinori , Konno Kohji , Nakabaru Mitsugu , Takano Saburo , Matsui Masao , Irisawa Juichi , Yatsui Kiyoshi
Published: November 2005

An intense pulsed light-ion beam generator, “ETIGO-1”, has been constructed at the Technological University of Nagaoka. In a preliminary stage of experiments done at less than half full power, we produced V
d (diode voltage)∼760 kV, I
d (diode current)∼65 kA, I
i (ion current)∼14 kA by use of a spherically-shaped, magnetically-insulated diode. Using a geometric focussing technique, we have obtained maximum current density J
i∼4 kA/cm2 (at the focussing point), yielding a focussing gain of ∼50. The focussing spot is observed to be less than 10 mm in diameter. The extracted ion current exceeds by more than a factor of 3 the spacecharge-limiting current of ions.
Reactive Ion-Beam Etching of Silicon Carbide
Authors: Matsui Shinji , Mizuki Sin'ya , Yamato Toshiya , Aritome Hiroaki , Namba Susumu
Published: November 2005

A reactive ion-beam etching technique using freon gas is developed for microfabrication in SiC. The enhancement of the etching rate of SiC is apparent by admixing O2 gas in CF4 gas. The etching rate of SiC for CF4+O2 (40%) gas is about 2 times larger than that for Ar gas. This technique appears to be very useful for producing various devices of SiC.
Two-Dimensional Antiphase Structures of the 2d-Cu3Pd Type Studied by High Voltage, High Resolution Electron Microscopy
Authors: Terasaki Osamu , Watanabe Denjiro
Published: November 2005

Structure images of the Cu-28 at.%Pd, Au-17 at.%Zn and Au-16.1 at.%Mg alloys having the 2d-Cu3Pd type structure were studied by 1 MV electron microscope. It was shown that deviation of alloy composition from stoichiometric A3B is accommodated at the second kind boundaries; a strong tendency of avoiding the formation of nearest neighbour pairs of Zn (or Mg) atom across the boundaries is observed in the Au-Zn and Au-Mg alloys, whereas an opposite tendency is seen in the Cu-Pd alloy. Part of the deficiency of Zn (or Mg) atoms is accommodated also at the first kind boundaries.
Infrared Power Delivery in the 2.7 µm Band in Fluoride Glass Fiber
Authors: Jinguji Kaname , Horiguchi Masaharu , Mitachi Seiko , Kanamori Terutoshi , Manabe Toyotaka
Published: November 2005

The 2.7 µm-band power-delivery characteristics of GdF3-BaF2-ZrF4-AlF3 glass fibers were investigated using an HF laser emitting at 2.6–3.0 µm wavelengths. Typical delivered power, without fiber damage, exceeded 0.6 W for a 300 µm core diameter and 4 meter long fiber, corresponding to a transmission efficiency of about 30%. The power-transmission capability in the 2.7 µm band makes the fluoride glass fiber very attractive as a flexible waveguide for laser printers and other applications.
Transient Temperature Variation of Injection Lasers
Authors: Suyama Masuo , Ogasawara Nagaatsu , Ito Ryoichi
Published: November 2005

We have observed the transient temperature variation of the active region of injection lasers. It is found that the heat generated in the active region is only about half the total input power. Analysis on the heat generation mechanisms suggests that the leakage current must be taken into account in buried-heterostructure lasers.
Frequency Stabilization of AlGaAs DH Lasers
Authors: Tsuchida Hidemi , Ohtsu Motoichi , Tako Toshiharu
Published: November 2005

The frequency of AlGaAs DH lasers was stabilized at the resonant frequency of a Fabry-Perot interferometer by controlling the injection current. The interferometer was controlled by a Lamb dip stabilized He-Ne laser at 633 nm. The frequency stability obtained here was 2.0×10-11≦σ≦2.1×10-9 for 10 ms ≦τ≦500 s, where σ and τ represent the square root of the Allan variance and the integration time, respectively.
ELS Study of Amorphous Si(Substrate)-SiO2(Film Overlayer) System with Varying Primary Electron Energy
Authors: Ito Toshimichi , Kataoka Yoshihide , Iwami Motohiro , Hiraki Akio
Published: November 2005

Electron energy loss spectroscopy (ELS) study was performed on amorphous silicon (a-Si; ∼0.3 µm) oxidized thermally (oxide thickness ∼33 Å). With a proper incident electron energy (\gtrsim1 keV), a new loss peak of ∼6.5 eV independent of a-Si and SiO2 loss signals was observed. The loss peak was assigned as an interfacial plasmon excitation from discussion about the boundary condition of such a system. The excitation energy was different from that in a crystal Si-SiO2 interface due to the change in dielectric constant between the crystalline and amorphous substrates.
A Modulated DLTS Method for Large Signal Analysis (C2-DLTS)
Authors: Okushi Hideyo , Tokumaru Yozo
Published: November 2005

For the analysis of deep-level parameters in semiconductors, a new DLTS (Deep-Level Transient Spectroscopy) method has been proposed, in which a squaring device for the capacitance-signal processing is used with the conventional DLTS system. This method (C2-DLTS) is simple and is especially effective in the precise analysis of large signals due to deep-level impurities and defects.
The Effect of Growth Temperature on the Mobility of Two-Dimensional Electron Gas in Selectively Doped GaAs/N-AlGaAs Heterostructures Grown by MBE
Authors: Hiyamizu Satoshi , Fujii Toshio , Mimura Takashi , Nanbu Kazuo , Saito Junji , Hashimoto Hisao
Published: November 2005

Ultrahigh two-dimensional electron gas mobilities of 244,000 cm2/Vs at 5 K and 117,000 cm2/Vs at 77 K with a sheet electron concentration of about 4.9×1011 cm-2 were achieved in a selectively doped GaAs/N-Al
x
Ga1-x
As (x=0.26) heterostructure grown at a “medium” temperature of 580°C by MBE. The mobility obtained at 5 K is much higher that any yet reported for MBE-grown semiconductor materials.