bluuebunny/crossref_metadata_2025 huggingface dataset:
New Non-Axisymmetric Eigenmodes Associated with an Edge Plasma Layer
Authors: Yamanaka Kaoru , Sugihara Ryo
Published: February 2005

The effects on Alfven waves of a rarefied plasma layer surrounding a cylindrical main plasma are investigated. The plasma is approximated with a two-step density profile and is assumed to be surrounded by a conducting wall. When the Alfvén resonance exists inside the rarefied plasma layer, two new modes are generated. One has its maximum of the wave intensity at the wall and is thus similar to a surface wave, and the other is a type of coaxial mode. These results are re-examined in a diffuse boundary plasma and the presence of these modes is confirmed.
Neutron Spectroscopy with a 3He Ionization Chamber on TFTR
Authors: Nishitani Takeo , Strachan J. D.
Published: February 2005

A gridded 3He ionization chamber had about 1–2% energy resolution, and was suitable for neutron spectroscopy of DD neutrons to measure the ion temperature. The gridded 3He ionization chamber was used to measure the neutron spectra on the tokamak fusion test reactor (TETR) during 1987. The ion temperature was deduced for one set of ohmically heated plasmas and agreed within 20% with that measured by other diagnostics. The deuterium concentration n
d/n
e and Z
eff were estimated with 40% uncertainty from the ion temperature measured with the neutron spectroscopy and the neutron source strength measured with fission chambers.
Secondary Battery Characteristics of Poly(3-alkylthiophene)
Authors: Kawai Tsuyoshi , Kuwabara Takao , Wang Shenglong , Yoshino Katsumi
Published: February 2005

The influence upon electrochemical characteristics of the alkyl chain length of poly(3-alkylthiophene) for use as electrode active materials of secondary batteries has been investigated by cyclic voltammetry, charge-discharge tests, and chronoamperometry. Redox potentials observed in both the cyclic voltammetry and the charge-discharge tests have been found to be dependent on the alkyl chain length, as well as redox reaction rate determined in the chronoamperometry. These dependencies are discussed on the basis of the steric effects of the alkyl groups on the higher-order structure along the poly(thiophene) main chain.
PSG Flow in High-Pressure Steam
Authors: Mayumi Shuichi , Ueda Seiji
Published: February 2005

Phosphosilicate glass (PSG) flow in high-pressure gas ambient is examined. PSG flow is enhanced with increasing pressure of steam ambient. Annealing temperature can be reduced by 80°C or the phosphorous concentration can be decreased by about 2 wt% by increasing the steam partial pressure from 0.95 kg/cm2 to 8.5 kg/cm2 from the viewpoint of planarization. The increase in pressure of dry N2 or dry O2 as ambient gas is not effective in enhancing PSG flow. The newly developed LSI (large scale integration) circuit process where a silicon nitride film underlies the PSG film is effective in preventing the oxidation of polysilicon and substrate during the flow in high-pressure steam. The FTIR result indicates that PSG films annealed in high-pressure steam absorb much less water than PSG films annealed in dry O2.
Metalorganic Chemical Vapor Deposition of c-Axis Oriented PZT Thin Films
Authors: Okada Masaru , Tominaga Koji , Araki Teruhiko , Katayama Shigehisa , Sakashita Yukio
Published: February 2005

Ferroelectric PZT thin films were prepared by the simultaneous deposition of PbO, ZrO2 and TiO2 on heated substrates under a reduced pressure of 6 Torr. Both tetraethyl lead-zirconium tetraisopropoxide and tetradipivaloylmethane-titanium tetraisopropoxide systems were examined as source materials. The films obtained at 500° to 650°C with those systems were constituted of PZT of the single perovskite phase, and highly c-axis-oriented films were grown on MgO(100) with the latter system. The c-axis orientation suggests an epitaxial growth of PZT on the substrates. With increasing molar fraction of ZrO2 in the PZT, the crystals were transformed from a tetragonal to rhom-bohedral structure. The film deposition rates were 100 to 1000 Å/min, i.e., more than ten times those obtained by the conventional sputtering method.
Initial Stage of the Interfacial Reaction between Nickel and Hydrogenated Amorphous Silicon
Authors: Kawazu Yunosuke , Kudo Hiroshi , Onari Seinosuke , Arai Toshihiro
Published: February 2005

The initial stage of the interfacial reaction between Ni and hydrogenated amorphous silicon has been studied mainly by in situ electrical resistance measurement. The change of the resistance in this system induced by the annealing at a constant heating rate shows a sudden drop, which corresponds to the amorphous-to-crystalline transformation of the Ni–Si intermixing layer. In situ resistance measurements for various intermixing layers in the initial stage demonstrate that the crystallization temperature becomes lower with the increase of the amount of Ni contained in the layer. The result means that the thermal stability of the intermixing layer decreases with its growth. It is suggested that the crystallization occurs when the amount of Ni contained in the intermixing layer reaches the critical thickness, which depends on the temperature.
Simulations of STM Images and Work Function for Rough Surfaces
Authors: Nakagiri Nobuyuki , Kaizuka Hiroshi
Published: February 2005

Computer simulations have been performed for constant current mode STM images and work function measurements. Rough surfaces used for the simulations are created by making clusters on a flat surface. Simulated STM images show that R.M.S. roughness depends not only on the tip radius but also on the topography of the sample surface. The effects of setting current and work function on STM images were also studied. The results show that the dependency of STM images on the tip radius is more significant than on the setting current or work function. Simulations of work function measurements show that the work function obtained experimentally is strongly dependent on the topography of the sample surface.
Axial Electric Field of He–Ne and He–Ar Gas Mixture Positive Column Plasmas in a Capillary Discharge Tube
Authors: Kaneda Teruo , Kubota Tadahiro , Chang Jen-Shih
Published: February 2005

The axial electric field of a positive column in a 0.8 mm-I.D. capillary discharge tube was measured for He–Ne and He–Ar gas mixtures at gas pressures from 0.1 to 10 Torr and discharge currents from 10 to 30 mA. The results show no significant percentage neon gas mixture effect on the axial electric field up to 10% neon in the He–Ne mixture. However, if we mix more than 1% of argon in helium, the axial electric field is observed to reduce significantly. The results also show that the axial electric field decreases with increasing percentages of neon and argon in He mixture.
Detection Technique of Negative Ions by Photodetachment in SF6 Low-Frequency Discharge
Authors: Ishikawa Itsuo , Koike Katsuhiro , Akitsu Tetsuya , Suganomata Shinji , Matsuzawa Hidenori
Published: February 2005

For the photodetachment, an optical system with dielectric multilayer mirrors was used to effectively irradiate an N2 laser pulse to the discharge space. At a phase of 30 kHz applied voltage just before the discharge current rapidly rises, and at a distance of 5 mm from the grounded electrode with a positive polarity in the SF6 discharge of 0.76 W at 0.2 Torr, the negative ion density measured is of the order of 108 cm-3.
Compositional Change of Sputtered YBa2Cu3Oy Films with Substrate Location
Authors: Matsutani Katsuhiro , Terada Norio , Jo Masatoshi , Ihara Hideo
Published: February 2005

The deposition process of superconducting YBa2Cu3O
y
thin films in rf magnetron sputtering was analyzed. Compositional change of sputtered films was observed as a function of distance from substrate to target and sputtering gas pressure. The composition of the films was changed by plasma damage and the oxygen affinity of component elements. The deviation of the film composition was significantly large near the target fringe, and was mainly caused by plasma damage. The optimum choices of target composition, substrate position and gas pressure resulted in reproducibly as-deposited high T
c films of stoichiometric composition.
Reaction Mechanisms in the OMVPE Growth of GaAs and AlGaAs
Authors: Mashita Masao
Published: February 2005

The thermal decomposition of TMA, TMG, TEG and AsH3 has been investigated by QMS measurements. Hydrogen is used as a carrier gas. The order of the decomposition temperature is AsH3>TMG>TMA>TEG. The reactivity of H2 is stronger on TMA than on TMG, which results in a lower decomposition temperature of TMA than that of TMG. Hydrogen hardly reacts on TEG. The decomposition of TMA is enhanced with increasing AsH3, while it is suppressed by a small addition of AsH3 compared with TMA alone. This suppression originates in the interaction between TMA and AsH3, or adduct formation. The relative incorporation rate of Al in AlGaAs growth decreases at lower temperatures or lower V/III ratios. This behavior can be explained by adduct formation.
Energy Band Model of Undoped a-Ge:H Prepared by Plasma CVD
Authors: Nakashita Toshio , Inoue Akira , Hagiwara Shingo , Haruki Satoshi , Uehara Fumiya
Published: February 2005

The infrared absorption, electronic properties including dark- and photoconductivities and optical properties of hydrogenated amorphous Ge thin films prepared by rf plasma CVD method at a substrate temperature of 130°C have been studied. It is found that hydrogens bond to Ge in a monohydride manner. An energy band model is proposed through the experimental results; the energy band gap is 1.0 eV, the Fermi level lies 0.35 eV below the conduction band, the electron trap level corresponding to the band tail edge is located 0.15 eV below the conduction band, and the hole trap level to the tail edge on the valence band side is situated 0.20 eV above the valence band.
Absorption Spectra and Photoluminescent Processes of AlAs/GaAs Disordered Superlattices
Authors: Kasu Makoto , Yamamoto Teiji , Noda Susumu , Sasaki Akio
Published: February 2005

The disordered superlattice, an artificially constructed material recently proposed, is fabricated. Photoluminescence and absorption properties of AlAs/GaAs disordered superlattices are compared with those of Al0.5Ga0.5As bulk alloy and (AlAs)2(GaAs)2 ordered superlattice. Their macroscopic AlAs compositions are the same 0.5, but their microscopic structures are different. Among them, the disordered superlattice exhibits the highest photoluminescent intensity in the temperature range from 4.2 K to 300 K. Absorption spectra of three different structured materials are measured, and tail states are observed in the disordered superlattice. Strong photoluminescent capability of the disordered superlattice is interpreted in terms of the tail states created by disordering in the atomic arrangement.
Calculation of Bond Lengths in Si1-xGex Alloys Based on the Valence-Force-Field Model
Authors: Ichimura Masaya , Nishino Yoichi , Kajiyama Hiroshi , Wada Takao
Published: February 2005

Bond lengths in crystalline Si1-x
Ge
x
alloys are calculated by the valence-force-field model. A zincblende like unit cell is used to simulate the structure of random alloys. The calculated length change normalized to the change predicted by the virtual-crystal approximation is about 0.35. The calculated bond lengths are compared with the experimental results obtained by EXAFS measurements.
Characterization of GdBa2Cu3O7-δ Thin Films by Raman Scattering
Authors: Hangyo Masanori , Nakashima Shin-ichi , Hasegawa Noboru , Hayashi Shigenori , Wasa Kiyotaka
Published: February 2005

Raman spectra of GdBa2Cu3O7-δ thin films (ortho-I, ortho-II and tetra) deposited on MgO substrates by rf magnetron sputtering were measured with an incident light beam whose direction was parallel or perpendicular to the c-axis. The oxygen content was estimated from the frequency of the Cu–O axial stretching mode for these films. The bending mode associated with oxygen at ∼320 cm-1 shows the Fano-type asymmetry for all three films indicating the strong electronphonon interaction in this system. This mode softens at around T
c with decreasing temperature for the ortho-I sample whereas it shifts upwards monotonically for the ortho-II and tetra samples. Comparison of this temperature dependence with that of YBa2Cu3O7-δ indicates that the softening of this mode is characteristic for the ortho-I phase.
ESR of CuO Particles in a Bi2(Sr, Ca)3Cu2Oy Crystal
Authors: Tagaya Kimihito , Fukuoka Nobuo , Nakanishi Shigemitsu
Published: February 2005

ESR measurements were performed at the X-band for a Bi2(Sr, Ca)3Cu2O
y
crystal over the temperature range from 77 K to room temperature, and a clear ESR line of superparamagnetic particles of CuO was observed with the external field of ca. 3 kOe. The resonance field of the absorption peak became a minimum at 230 K, at which point the absorption intensity became a maximum. Furthermore, an anisotropy of the resonance field was observed for another broad absorption. Possible interpretations for the results are discussed in terms of magnetic anisotropies in CuO particles.
Near Band Edge Photoacoustic Spectra of p-Si Single Crystals
Authors: Ikari Tetsuo , Yokoyama Hirosumi , Shigetomi Shigeru , Futagami Koji
Published: February 2005

Room-temperature photoacoustic (PA) spectra of p-type silicon single crystals were measured by using a piezoelectric transducer as a detector. Two peaks at 1.08 and 1.20 eV were observed. Since the peak at 1.08 eV appears only in boron-doped p-type samples, we consider this peak to be due to the boron impurity level. The 1.20 eV peak beyond the band gap observed for both p- and n-type samples is considered to be an apparent one due to the bending of the sample in the highly absorbing region. The effect of the modulation frequency and the detector geometries are explained well by taking into account the sample bending and the pyroelectric effect.
Positron Localisation in Metallic Glasses in Terms of the Crystalline Embryo Model
Authors: Michno Zbigniew
Published: February 2005

One-dimensional angular correlation studies of the Ni73TM5Si10B12(TM=V, Cr, Mn, Fe and Co) metallic glasses have been performed. The analysis of the angular correlation data, consisting of a deconvolution into one Gaussian and two parabolic curves, indicates the possibility that two 'species' of the nearly free electrons are present in the particular materials. We have attempted to verify the physical reliability of this fitting procedure by assuming that the crystalline embryos tend to localise the thermalised positrons. It is shown that some of the estimated parameters describing the shape of the angular correlation curves systematically change with changing the atomic number of the TM admixtures. It allows the effect of TM on the thermal stability to be precisely recognised.
Defects Induced by Wafer Processing and Thermal Treatment in InP Probed with Monoenergetic Positrons
Authors: Uedono Akira , Tanigawa Shoichiro
Published: February 2005

Variable-energy positron-beam studies have been made on InP single crystals. Doppler broadening profiles of the positron annihilation and the mean diffusion length of positrons were found to be sensitive to defects under the subsurface region. For a specimen after high-quality polishing, vacancy-type defects with a concentration of 1018 cm-3 were observed in the range of 0∼400 nm. For the specimen after heat treatment, a damaged layer introduced by dephosphorization was observed. An overlayer containing monovacancies, with a thickness of 140 nm, was found to be formed after 450°C annealing.
A Study of CCl2F2 Magnetron Ion Etching Damage and Contamination Effects in Silicon
Authors: Kuroda Tsukasa , Iwakuro Hiroaki
Published: February 2005

X-ray photoelectron spectroscopy has been used to evaluate Si surfaces exposed to magnetron plasma in CCl2F2 gas. Plasma exposure of Si surfaces results in a contamination film 12–33 Å thick and a damaged layer in the Si substrate. The contamination film consists of C–C, C–F, and C–Cl–F and/or F–F bondings. In addition, the C and F atoms penetrate into the Si substrate. On the other hand, the damaged layer consists of lattice defects and the contamination by the C and F atoms. Furthermore, from electrical measurements on Al/n-Si Schottky diodes, the damage depths are determined as a function of rf power. It is found that the damage depths correlate with the energy of ions impinging on the Si surface during plasma exposure.
Time-Resolved Luminescence Spectra of Dosimeter Glasses
Authors: Miyoshi Tadaki
Published: February 2005

Time-resolved luminescence spectra were measured at 300 K in dosimeter glasses under N2 laser excitation. Two emission bands were observed at 430 nm and 600 nm. The 430 nm band is due to the predose and decays rapidly. The 600 nm band is induced with gamma-ray irradiation and decays gradually. The decay time of the 600 nm band becomes longer with increase in the delay time.
Radical Emissions and Butane Diffusion Flames Exposed to Uniform Magnetic Fields Encircled by Magnetic Gradient Fields
Authors: Aoki Takashi
Published: February 2005

When butane diffusion flames were exposed to uniform magnetic fields encircled by magnetic gradient fields, emission intensities of such transitions as A2Σ→X2Π of OH*, intensities of continuous spectra arising from the particle cloud radiation, and flame temperatures decreased, while flame dimensions increased. However, the changes in these quantities are very small compared with those for flames exposed to magnetic gradient fields reported previously. The above phenomena are ascribable to the fact that the magnetic gradient fields inevitably existing at the pole fringes influence the convectional flow of the combustion, although the gradient fields are far from the flames and not acting directly on the flames. Attention should be given to such gradient fields when research on the influence of a uniform magnetic field on combustion is undertaken.
Superconducting Electromagnet for X-Ray Diffraction
Authors: Tajima Keisuke , Suzuki Naohumi , Oguchi Keiichiro
Published: February 2005

An electromagnet of small size for the X-ray diffraction experiment has been made using a superconducting coil. The measurement can be performed under a magnetic field up to 9 kOe.
Influence of Substrate Misorientation on Surface Morphology of Be-Doped GaAs Grown by MBE
Authors: Mochizuki Kazuhiro , Goto Shigeo , Kakibayashi Hiroshi , Kusano Chuushiro
Published: February 2005

The surface morphology of MBE-grown Be-doped GaAs was studied by RHEED, SEM and TEM. {411}A facets were found on the (100) surface for Be 6×1019 cm-3 doping at a growth temperature of 630°C. The surface roughness due to this faceting was suppressed by misorienting the GaAs substrate from (100) toward (111)A; a 19.5° misorientation, i.e., a (411)A substrate, was found to be effective in realizing a smooth surface, even for Be 1×1020 cm-3 doping.
Preparation of Superconducting Bi-Sr-Ca-Cu-O Coating Films by the Sol-Gel Method Using an Aqueous Solution of Metal Acetates
Authors: Zhuang Haoren , Kozuka Hiromitsu , Yoko Toshinobu , Sakka Sumio
Published: February 2005

Superconducting Bi-Sr-Ca-Cu-O coating films have been prepared on YSZ (yttria-stabilized zirconia) and Al2O3 substrates by the sol-gel method using an aqueous solution of metal acetates containing tartaric acid. A film of 20 µm thickness on the YSZ substrate showed T
c(onset) at 115 K and T
c(end) at 79 K, consisting of Bi2Sr2CaCu2O
x
crystals with the c-axis perpendicular to the substrate. The reaction between the film and the YSZ and Al2O3 substrates produced CaZrO3 and CuAl2O4, respectively, during heat treatment, which suppresses the formation of superconducting phases and causes the degradation of the superconducting properties of the films.
Room-Temperature CW Operation of AlGaAs/GaAs SQW Lasers on Si Substrates by MOCVD Using AlGaAs/AlGaP Intermediate Layers
Authors: Egawa Takashi , Kobayashi Yasufumi , Hayashi Yasuhiko , Soga Tetsuo , Jimbo Takashi , Umeno Masayoshi
Published: February 2005

Room-temperature CW operation of all-MOCVD-grown Al0.3Ga0.7As/GaAs SQW lasers on Si substrates with Al0.5Ga0.5As/Al0.55Ga0.45P intermediate layers has been demonstrated for the first time. The averaged threshold current density and differential quantum efficiency of the lasers grown with the Al0.5Ga0.5As/Al0.55Ga0.45P intermediate layers are 2.23 kA/cm2 and 50.3%, respectively, which are superior to those of the lasers grown by the two-step growth technique. The characteristics of the lasers using this technique are more uniform than those grown by the two-step growth technique.
Liquid-Crystal-Based Optoelectronic Hybrid Structure for Optical Parallel Processing Devices
Authors: Yamazaki Hirofumi , Yamaguchi Masayasu
Published: February 2005

An easy-to-handle optical device structure is proposed for optical parallel processing devices. This is an opto-electronic hybrid structure consisting of liquid crystal polarization controllers and polarizing beam splitters. Experimental memory and AND cells based on this structure are successfully demonstrated.
Very Fast Integrated Optoelectronic Logic for Parallel Computation Using Photodiode Gates
Authors: Kamiyama Hiroyuki , Shouno Atsuo , Umemoto Yasunari , Kamiya Takeshi
Published: February 2005

A new configuration of an integrated optoelectronic logic unit using GaAs photodiode gates is proposed. Implementation of AND and EOR logic units are performed monolithically using GaAs/AlGaAs multilayer structures. Discussions are made on the realization of the full adder by means of optical feedback between the photodiode logic array and the surface emitting diode laser array.
Optical Logic Operations Using Three-Beam Phase-Conjugate Interferometry
Authors: Ogusu Masahiro , Tanaka Shun-ichi , Kuroda Kazuo
Published: February 2005

An experimental arrangement of the three-beam phase conjugate interferometer is proposed in which a phase of any of the three signal beams is easily and independently controlled by the small rotation of a mirror set in each optical path, and its performance is reported. Using this arrangement, several optical logic operations of two binary patterns, such as XOR, OR, \overlineXOR and NAND, are demonstrated.
Beam Scanning Binary Logic
Authors: Itoh Hideo , Mukai Seiji , Watanabe Masanobu , Mori Masahiko , Yajima Hiroyoshi
Published: February 2005

A novel optoelectronic logic operation technique using a beam scanning laser diode is proposed. This technique realizes fundamental logic operation gates and a spatial encoder with simple configurations.
Bipolar Morphology and Its Applications
Authors: Asano Akira , Itoh Kazuyoshi , Ichioka Yoshiki
Published: February 2005

Recently, mathematical morphology has been applied to image processing and analysis because of its simplicity and shiftinvariance. We propose novel morphological operations of image differentiation such as erosion and dilation for morphological smoothing. It is called bipolar morphological operation. We show that bipolar morphological operation is closely related to a differential operator we recently proposed. This operator, called RONDO (rank-order based nonlinear differential operator), is a generalized weighted median filter with positive and negative weight coefficients.
Optical Implementation of a Holographic Heteroassociative Memory System
Authors: Kim Eun-Soo , Lee Seung-Hyun , Lee Woo-Sang
Published: February 2005

A holographic heteroassociation system that can store and reconstruct a sequence of associative information, based on the optical associative memory loop is described.
In this system, the associative information is stored in two multiplexed Fourier transform holograms with different sequential arrangements, and the reference beam forms an associative link between them. Depending on the spatial arrangement style, many interesting applications can be possible.
Some experimental results on cyclic search using this system are demonstrated.
β-SiC Formation by Low-Energy Ion-Doping Technique
Authors: Deguchi Masahiro , Yoshida Akihisa , Kitagawa Masatoshi , Hirao Takashi
Published: February 2005

β-SiC was prepared on silicon (Si) substrates by a low-energy ion-doping technique without mass separation. Carbon (C) and hydrogen (H) ions obtained from a discharge of diluted methane gas with hydrogen gas were implanted into Si substrates at the DC acceleration voltage of 3.0 kV. The dependence of carbon dose, dilution ratio and annealing temperature (T
a) on the Si-C bond formation was investigated. Simultaneous implantation of H ions as well as C ions was effective for tight Si-C bond formation at low T
a(<800°C). By annealing at high T
a(>800°C), the β-SiC network was formed in the implanted layer. With increasing carbon dose, the amount of the β-SiC increased and was saturated at the dose of ∼4×1015 ions/cm2.
Infrared Spectroscopy of Metal-MgO Single Crystalline Composite Films
Authors: Wada Mitsuo , Tanaka Nobuo
Published: February 2005

Infrared transmission spectra were measured for single crystalline composite films of nm-sized metal (Au, Fe and Cr) crystallites and magnesium oxide (MgO). The absorption lines of the TO phonon of MgO were observed around 400 cm-1. The widths of absorption lines in Fe-MgO and Cr-MgO composite films are about three times wider than those of vacuum-deposited MgO films, whereas they are twice as wide in the Au-MgO composite films. These features are tentatively understood in terms of the difference in the bonding strength of the metals and oxide.
Optimum Deflection Angle of Double Angular Focusing Two-Magnet System for Use in Nuclear Time Spectroscopy
Authors: Sakata Akihiko , Yamada Yoshihiro , Murakami Tetsuro
Published: February 2005

The dependence of the flight-time spread of charged particles in a deflecting magnet system on the deflection angle of the magnets has been investigated by means of a computer simulation method. The following results were obtained: in the case where the charged particles involve the momentum deviation, (1) the flight-time spread depends strongly on the deflection angle; (2) the minimum flight-time spread is realized at the deflection angle of about 81° when the system is composed of two identical sector magnets. The FWHM value of the flight-time spread is expected to be ∼40 ps in transmission of ∼0.019% for the source diameter of 3 mm.
Contribution of the Charge-Exchange Process for Inverted Population in a Recombining Plasma
Authors: Furukane Utaro , Sato Kuninori , Takiyama Ken , Oda Toshiatsu
Published: February 2005

We have numerically determined that high gain for the laser oscillation of the CVI 13.5 nm line is promoted by the contribution of the charge-exchange process, C6++H(1S) →C5++H+. In particular, the contribution shows a notable effect in some lower-temperature (∼10 eV) recombining plasmas.
Implementation of Optical Ternary Logic Operations Using a Twin-Stripe Laser Diode
Authors: Watanabe Masanobu , Mukai Seiji , Itoh Hideo , Yajima Hiroyoshi
Published: February 2005

Three basic logic operations of the symmetric ternary logic system have been optically implemented using a ternary digital device made up of a twin-stripe laser and a positive feedback circuit. The logic device is suitable for balanced temary processing which has more advantages than does ordinary ternary processing.
Phase Conjugation in Methyl-Orange-Doped PVA Films by Photoinduced Anisotropy
Authors: Egami Chikara , Nakagawa Kazuo , Fujiwara Hirofumi
Published: February 2005

The influence of photoinduced anisotropy (dichroism and birefringence) in methyl-orange-doped polyvinyl alcohol film upon optical phase conjugation is investigated. The reflectivity of the phase-conjugate (PC) beam due to degenerate four-wave mixing (DFWM) is measured under the condition that the polarization states of a probe and two pump beams are mutually orthogonal. The more efficient PC beam generates at 515 nm rather than at 488 nm. At 515 nm, the reflectivity of the PC beam exceeds 10 percent about 30 minutes after the initiation of DFWM. It was found that birefringence rather than dichroism contributes to the generation of the PC beam at 515 nm.
Construction of Modularized OPALS Using Optoelectronic Devices
Authors: Miyazaki Daisuke , Tanida Jun , Ichioka Yoshiki
Published: February 2005

OPALS is an optical digital computing system based on optical array logic. The modularized OPALS is one version of OPALS composed of functional modules utilizing electronic techniques. We have constructed the preliminary experimental system of the modularized OPALS using discrete optoelectronic devices. The operation of the system is verified by the execution of several kinds of parallel processing; e.g., neighborhood operations and 3 bit addition.
Multiple Matched Spatial Filtering with Corresponding Symbols by the Hybrid System
Authors: Kamemaru Shun-ichi , Nagaoka Toshiyuki , Kakuta Mitsugu , Shimizu Isao
Published: February 2005

A system for multiple pattern recognition without observing peak autocorrelation signals is described. A multiplexed matched spatial filter is used for multiple operations. The reconstructed peak signals are not directly used for recognition. They are first fed into a frame buffer memory via a CCD camera to be processed by a microcomputer. Unknown inputs are finally recognized by taking a glance at symbols, which are displayed on a CRT screen and are deduced from the peak signals by the microcomputer. The system presents easier recognition for observers who are not expert in matched filtering.
Low-Temperature Growth of ZnSe by Photoassisted Molecular Beam Epitaxy
Authors: Fukada Takashi , Matsumura Nobuo , Fukushima Yasumori , Saraie Junji
Published: February 2005

ZnSe epilayers have been successfully grown at a low temperature of 150°C for the first time by photoassisted molecular beam epitaxy. A He-Cd laser (441.6 nm) with an intensity of about 300 mW/cm2 was used as a light source. The free-exciton line in photoluminescence spectra at 11 K was sharp and strong, comparable with that of unirradiated epilayers grown at 340°C which is the optimum growth temperature without irradiation.
Electroluminescence of AlAs/GaAs Disordered Superlattices
Authors: Kasu Makoto , Yamamoto Teiji , Noda Susumu , Sasaki Akio
Published: February 2005

The double hetero (DH)-structure pin diode in which an undoped AlAs/GaAs disordered superlattice is used for the active layer is fabricated, and electroluminescence (EL) from the diode is measured at room temperature. The DH-structure pin diode whose active layer is either Al0.5Ga0.5As bulk alloy or (AlAs)2(GaAs)2 ordered superlattice is also fabricated for the comparison of EL. The EL intensity from the disordered superlattice is 2.5 and 10 times stronger than those from the last two diodes, respectively, and the EL peak energy of 1.88 eV from the disordered superlattice is lower than those from the other two diodes, i.e., the red shift.
Measurement of the Minority-Carrier Lifetime in a Semiconductor Wafer by a Two-Mercury-Probe Method and Its Application to Evaluation of the Surface Recombination Velocity
Authors: Suzuki Eiichi , Hayashi Yutaka
Published: February 2005

It is shown that the minority-carrier lifetime τ and diffusion coefficient D can be nondestructively evaluated by the two-mercury-probe method and analysis technique, even in the p-type silicon wafers with low resistivity. Furthermore, it is also demonstrated that the evaluation of the surface recombination velocity s and its dependence on the wafer surface conditions is possible by applying the developed measurement and analysis method.
Image Formation of Periodic Objects Illuminated by Undulator Radiation in a Zone Plate Microscope
Authors: Kagoshima Yasushi , Aoki Sadao , Kakuchi Masami , Maezawa Hideki , Ando Masami
Published: February 2005

It is of great importance to understand image formation by zone plates (ZP's) in X-ray microscopy using ZP's as optical devices. Image formation by a ZP is diagrammatically analyzed. First, an object is illuminated by a monochromatic plane wave. It is shown that images overlapping with one another can be separated by means of an off-axis diaphragm. Secondly, the object is illuminated by undulator radiation (UR). Finally, a one-dimensional transmission grating used as an object is illuminated by UR. It is shown that its diffraction images appear on various parabolic curves. The experimental result agrees quite well with the calculated one.
High-Energy-Electron Acceleration by a Pulse Electromagnetic Wave in a System of the Inverse Synchrotron Radiation
Authors: Kawata Shigeo , Watanabe Hiroaki , Manabe Atsushi , Kuroda Hiroto
Published: February 2005

A new electron acceleration mechanism of the inverse synchrotron radiation which was proposed in a paper (Jpn. J. Appl. Phys. 28 (1989) L704) is reexamined in order to show that an electron can be accelerated well by a realistic Gaussian-pulse electromagnetic wave. Numerical analyses and particle simulations were performed in addition to the simple analyses which present the scaling law for the acceleration energy and the expression for the optimal applied weak static magnetic field of this system.
(11n)-Oriented BiSrCaCuO Thin Film Formed on SrTiO3(110) Substrate by RF Magnetron Sputtering
Authors: Kuroda Ken'ichi , Kojima Kazuyoshi , Wada Osamu , Tanioku Masami , Yokoyama Kazuo , Hamanaka Koichi
Published: February 2005

A superconducting BiSrCaCuO thin film was grown on a SrTiO3(110) substrate at 660°C by sputtering a single target. The RHEED observation showed that the c-axis of the film meets at an angle of about 42° with the substrate surface. The XRD measurement showed that the film has a main peak at 2 θ=31.2°. From these results, the film is considered to chiefly consist of a 2212 phase with (117) orientation and/or a 2212/2223 superlattice phase with (118) orientation. The film surface has a stripelike texture which probably corresponds to the film orientation. The zero-resistivity temperature of the film was lower by 20 K than that of the film formed on the SrTiO3(100) substrate.
Exact Theory of Nonlinear Surface Polaritons: TM Case
Authors: Kushwaha Manvir S.
Published: February 2005

It has long been argued that Maxwell's equations cannot be exactly solved for nonlinear surface/interface TM modes. This short communication is intended to demonstrate that analytically exact solutions for nonlinear TM modes are possible. We have calculated the dispersion relation and the power carried by the nonlinear surface polaritons (NLSP) propagating along an interface between an optically (Kerr-like) nonlinear and a linear media. We emphasize that the present treatment is absolutely free from any approximation.
Optimization and Characterization of 780 nm AlGaAs Quantum Well DFB Laser Diodes
Authors: Hirata Takaaki , Suehiro Masayuki , Maeda Minoru , Yamada Noriyuki , Hihara Mamoru , Hosomatsu Haruo
Published: February 2005

AlGaAs quantum well DFB laser diodes with a wavelength of 780 nm have been fabricated using two-step MOVPE growth and EB lithography. Comparing several quantum well structures emitting 780 nm wavelength, the optimum structure was determined to be about 5 nm thick with a 0.06 Al mole fraction where low threshold current and low internal loss are realized. The GRIN-SCH structure with a carrier blocking layer was also utilized to improve the characteristic temperature of a two-step-growth laser diode. The resulting threshold current, characteristic temperature and spectral linewidth are 11 mA, 244 K and 760 kHz, respectively.
Gas-Sensitive Junction Characteristics of Poly(3-alkylthiophene) Schottky Diodes
Authors: Ohmori Yutaka , Takahashi Hiroyuki , Kawai Tsuyoshi , Yoshino Katsumi
Published: February 2005

Novel gas-sensitive junction characteristics have been observed in poly(3-alkylthiophene) Schottky diodes. It has been found that there are two types of gases. One type of gas suppressed the reverse bias current in the Schottky diodes and the other enhanced the reverse bias current. These results have been explained in terms of a gas-dependent band scheme, where they were also confirmed by the capacitance-voltage measurements.
Effect of Silicon Surface Cleaning on the Initial Stage of Selective Titanium Silicide Chemical Vapor Deposition
Authors: Saito Kunio , Amazawa Takao , Arita Yoshinobu
Published: February 2005

The influence of silicon surface cleanness on the nuclei density of titanium silicide in the initial stage of selective chemical vapor deposition was studied. The nuclei density was greatly increased as the cleanness of the silicon surface was improved. An in situ silicon surface cleaning using a low-pressure silane gas at a low temperature (700–740°C) was effective in increasing the nuclei density of titanium silicide. About a 500-Å-thick titanium silicide film with a low resistivity near the bulk value and a smooth morphology has been obtained with full selectivity by in situ cleaning using silane gas.
Crystal Structure of a Pb-Based Copper Oxide (Pb0.5Cu0.5)(Sr1.1La0.9)CuOz
Authors: Nakahigashi Kiyotaka , Sasakura Hiroyuki , Watari Koji , Minamigawa Shinnosuke
Published: February 2005

The crystal structure of a Pb-based copper oxide superconductor (Pb0.5Cu0.5)(Sr1.1La0.9)CuO
z
(T
c=31.5 K) has been analyzed by the Rietveld method on the basis of the X-ray powder diffraction data. The material has a flat CuO2 sheet and a flat (Pb/Cu)O sheet which were sandwiched between two zigzag (Sr/La)O sheets. The crystal has a tetragonal symmetry with a probable space group P4/mmm and its lattice parameters are a=3.7685(6) Å and c=8.6972(6) Å. The Cu atom on the CuO2 sheet has sixfold octahedral coordination with the apexes reduced by about 3% along the c-axis.
Growth Mode of {111} Surfaces of Diamond Crystals Synthesized by Hot-Filament CVD Method
Authors: Hirabayashi Keiji , Kurihara Noriko Iwasaki
Published: February 2005

The substate temperature dependence of the morphology and the fine structures on {111} surfaces of diamond crystals have been studied using a high-resolution scanning electron microscope to elucidate the mechanism of the crystal growth. A layer-by-layer crystal growth of the {111} surface is suggested from the fact that the {111} surface structures are the same in diamond crystals deposited at different temperatures in spite of the difference in the shapes of {111} surfaces.
Triangular Structures on {111} Surfaces of Diamond Crystals Synthesized by the Hot-Filament CVD Method
Authors: Hirabayashi Keiji , Kurihara Noriko Iwasaki
Published: February 2005

The morphology of the diamond crystal deposited by a hot-filament method has been studied by a high-resolution scanning electron microscope to elucidate the mechanism of the crystal growth. The growth of {111} faces is multinucleation, and the {111} surface consists of both many small triangles whose orientations are the same as those of the original {111} face of a cubo-octahedron and triangular pits surrounded by three triangles. The appearance of three {110} surfaces at the edge of the {111} surface is possibly explained by the inhomogeneity of the active carbon concentration oh the {111} surface.
Optimization of the Amorphous Layer Thickness and the Junction Depth in the Preamorphization Method for Shallow-Junction Formation
Authors: Tanaka Akira , Yamaji Tetuo , Uchiyama Akira , Hayashi Takahisa , Iwabuchi Toshiyuki , Nishikawa Satoshi
Published: February 2005

A 0.1- µm-deep p+/n junction was formed by the Si+ preamorphization method. The thickness of the preamorphized layer and the junction depth were optimized systematically. It was found that the junction must be formed at a depth 70–90 nm greater than that of the amorphous/crystal (a/c) interface to reduce leakage current density J
1 to less than 1×10-8 A/cm2. Furthermore it was confirmed that the preamorphized layer thickness influences the dependence of J
1 on the distance between the junction and a/c interface and that a thinner preamorphized layer forms a thinner or lower-defect-density residual defect layer.
Oxidation-Retarded Diffusion of Bismuth in Silicon
Authors: Ishikawa Yutaka , Kobayashi Izumi , Nakamichi Ichiro
Published: February 2005

The effect of thermal oxidation of silicon on the diffusion of bismuth in silicon has been investigated quantitatively. The diffusion coefficients of bismuth during drive-in are determined by adopting the best-fitted parameters in the numerical simulation of the experiments. The diffusion of bismuth is retarded by the thermal oxidation of silicon. The degree of retardation is less than that of antimony. The oxidation time dependence of the retardation is more marked than that of antimony. These contradictions suggest that the diffusion mechanism of bismuth in silicon may not be a simple dual mechanism.
Optical Properties of New Kinds of Thermal Donors in Silicon
Authors: Kamiura Yoichi , Suezawa Masashi , Sumino Koji , Hashimoto Fumio
Published: February 2005

We have found with far-infrared (FIR) absorption spectroscopy that prolonged annealing of silicon at 470°C leads to the generation of new FIR absorption bands. They are strongly correlated with a recently observed new type of oxygen-related thermal donor (NTD) which is different from either the so-called thermal donor (TD) or new donor (ND) in nature. It is deduced from the temperature dependence of FIR spectra that NTD is a family of shallow double donors just like TD. However, there is a drastic difference between TD and NTD; TD gives rise to sharp absorption lines, while NTD results in broad absorption bands. The possible origins of such a difference are discussed.
Crystal-Originated Singularities on Si Wafer Surface after SC1 Cleaning
Authors: Ryuta Jiro , Morita Etsuro , Tanaka Toshiro , Shimanuki Yasushi
Published: February 2005

It is clarified that a new type of singularity is formed on Si wafer surface by the Standard Cleaning 1 (SC1) of the RCA cleaning process. Such singularities are perceived by laser particle counters as small particles on wafers. It is shown that the singularities correspond to small shallow pits caused by the etching effect of the SC1 cleaning solution. The origin of the pits is presumed to be some kind of defect in the melt-grown crystals.
Ultrafast Response Evaluation of Virtual Excitation by Off-Resonant Optical Pulse Mixing in GaAs/AlGaAs Quantum Well Structures
Authors: Sakata Yasutaka , Yamanishi Masamichi , Yamaoka Yoshifumi , Kodama Shuji , Kan Yasuo , Suemune Ikuo
Published: February 2005

Experimental results on the ultrafast response of virtual excitations through the observation of photocurrents in GaAs/AlGaAs quantum well structures are demonstrated with an off-resonant optical pulse mixing technique. A surprisingly short spike is discovered in the photocurrent autocorrelation signals. The observed spike almost reproduces the shape of the optical pulse with a duration of 750 fs. With a fair correspondence of the experimental data with theoretical results based on Bloch equations taking into account the influence of the a
c Stark effect, the observed short spike is ascribed to the ultrafast response of virtual excitations.
Potential Barrier Height Analysis of AlGaInP Multi-Quantum Barrier (MQB)
Authors: Takagi Takeshi , Koyama Fumio , Iga Kenichi
Published: February 2005

We have examined the electron wave reflectivities of the AlGaInP-based multi-quantum barrier (MQB) with changing of several parameters such as well and barrier thickness and pair number. We have optimized the MQB structure by clarifying several choices of the MQB parameters. Even in the 630-nm-range AlGaInP lasers, we can obtain effective potential barrier height 2 times greater than the classical potential barrier height U
0 in the MQB composed of relatively nallow superlattices. The increased potential barrier height is about 114 meV and this suggests the possibility of higher-temperature CW operation of 630-nm-range AlGaInP lasers.
Anomalous Electrical Resistivity of Bi-Sr-Ca-Cu-O System at High Temperature
Authors: Nagai Hiroshi , Kakuzen Masahiro , Yokota Masaru , Majima Kazuhiko
Published: February 2005

The electrical resistivity of Bi-Sr-Ca-Cu-O and Bi(Pb)-Sr-Ca-Cu-O superconductors at high temperatures was studied in relation to superconducting properties. The resistivity of the samples with a low-T
c phase showed hysteresis around 300 and 650°C between the heating and cooling processes. No hysteresis was detected for nearly single phase high T
c. For the low-T
c samples, it was confirmed that the T
c, the material resistivity and the high temperature resistivity were strongly dependent on the quenching temperature. Weight loss was detected around 300°C in the heating process, but it was not detected in the cooling process.
A Promising Jc Enhancement in YBa2Cu3Ox by “Grain Coating”
Authors: Zheng Xu-Guang , Kuriyaki Hisao , Hirakawa Kazuyoshi
Published: February 2005

A “grain coating” method is proposed to improve the superconducting property of intergrain junctions. In this process, Ag is coated onto the surface of crystalline grains by vacuum evaporation. A remarkable enhancement of J
c is obtained with a very thin (∼1 nm) Ag coating of less than 0.01% in weight proportion. The dependence of J
c on the coating thickness seems to be related to the coherence length in this oxide superconductor.
Critical Current and Activation Energy in Bi2Sr2Ca1Cu2Ox Films after Ion Irradiation
Authors: Hoshiya Taiji , Takamura Saburo , Aruga Takeo , Kobiyama Mamoru , Miura Sadahiko , Kubo Yoshimi , Shohata Nobuaki
Published: February 2005

The temperature dependence of electric voltage in Bi2Sr2Ca1Cu2O
x
films after He ion irradiation is measured for various electric currents and magnetic fields. From the thermally activated behavior of flux lines, the activation energy and the relation between the transition temperature and the Lorentz force are obtained. The pinning energy and the critical current density in Bi2Sr2Ca1Cu2O
x
single-phase films decrease due to He ion irradiation.
Preparation of Nearly Stoichiometric Superconducting Y-Ba-Cu-O Films by an MOCVD Technique Using Ozone
Authors: Ohnishi Hiroshi , Harima Hiroshi , Kusakabe Yoshihiko , Kobayashi Minoru , Hoshinouchi Susumu , Tachibana Kunihide
Published: February 2005

Superconducting Y-Ba-Cu-O films of nearly stoichiometric composition (Y:Ba:Cu=1:2:3.6) were prepared by an MOCVD technique on MgO(100) substrates at 650°C without postannealing. By introducing ozone into the reactor, we obtained a film with higher zero resistive temperature (75 K) and better surface morphology and c-axis orientation, compared to a film of the same composition prepared without ozone.
High-Tc (95 K) As-Grown Superconducting Bi-Sr-Ca-Cu-O Thin Films
Authors: Ohbayashi Kazushige , Anma Masatoshi , Takai Yoshiaki , Hayakawa Hisao
Published: February 2005

As-grown superconducting thin films of the Bi-Sr-Ca-Cu-O system were prepared on MgO(100) substrates by a three-target rf magnetron sputtering system with a regulated shuttering technique. Using this system, Bi-Sr-Ca-Cu-O superconducting high-T
c-phase films (700 Å) with a thin Bi-Sr-Cu-O semiconductor-like-phase buffer layer (70 Å) were deposited on MgO (100) substrates under rigorous control of the film composition at 760°C. The superconducting transition temperature of the as-grown film was 115 K (T
con
) and 95 K (T
czero
). The surface of this film was very smooth and uniform.
1.5 µm Range Tunable Twin-Guide Laser Fabricated by All MOVPE
Authors: Yamamoto Eiji , Hamada Madoka , Nakajima Shin-ichi , Nogiwa Seiji , Suda Kazuya , Oki Tokukoh
Published: February 2005

A calculation method for tunable twin-guide (TTG) laser tuning characteristics and the threshold current density depending on the modulation layer band-gap wavelength is presented. Experimental results for a 1.5 µm range TTG laser fabricated by all MOVPE are given for the first time. The optimized band-gap wavelength of the modulation layer is approx. 1.3 µm ∼1.4 µm and the maximum tuning range is approx. 9 nm by analysis. In the preliminary fabrication, the threshold current was 23 mA and the tuning range was 2.6 nm.