bluuebunny/crossref_metadata_2025 huggingface dataset:
An Observation of Benzotriazole (BTA) Adsorption on Cu(110) by the Ultra High Vacuum (UHV)-Scanning Tunneling Microscope (STM) and Low Energy Electron Difiraction (LEED)
Authors: Cho Kyehyun , Kishimoto Jiro , Tomihiro Hashizume Tomihiro Hashizume , Toshio Sakurai Toshio Sakurai
Published: October 2002

We have investigated Benzotriazole (BTA) adsorption structures and kinetics on the clean Cu(110) and oxygen reconstructed Cu(110)-2×1 surfaces. The first atomicaly resolved scanning tunneling microscope (STM) images showed that BTA adsorbed on the clean Cu(110)-1×1 surface to form the c(4×2) commensurate structure, agreeing the c(4×2) LEED pattern. On the other hand, STM images of BTA adsorbed on the oxygen induced Cu(110)-2×1 surface were a fully disordered structure. In kinetic point of view, BTA molecules should adsorb preferentially on the oxygen induced Cu(110)-2×1 missing row compared to the clean Cu(110) surface.
New Method of Tracing Interior Projectile Motion in a Gas Gun by Inline Holographic Velocimetry
Authors: Mori Yasuhito , Iwata Yukimitsu , Nishihara Keishi , Sachiko Hatano Sachiko Hatano , Kunihito Nagayama Kunihito Nagayama
Published: October 2002

For continuous recording of projectile motion in a gas gun, a new method, “inline holographic velocimetry”, is proposed and demonstrated. The inline hologram pattern of a wire is recorded by a streak camera via a mirror, which ismovingbetween the wire and the recording plane. The mirror is glued onto the nose of an accelerating projectile. The projectile motion can be obtained precisely by analyzing the fringe spacings which gradually become narrower with increasing displacement. It was found that the projectile acceleration is almost constant except in the early stage.
Wetting Behavior of Liquid on Geometrical Rough Surface Formed by Photolithography
Authors: Akira Kawai Akira Kawai , Hitoshi Nagata Hitoshi Nagata
Published: October 2002

The effect of roughness on the wettability is studied. The rough surface is constructed with photoresist micropatterns which are formed by photolithography. The aspect ratio is defined as the length ratio between the pattern space and its height. Contact angles of three kinds of liquids, pure water, diiodomethane and ethylene glycol, increase and saturate with the increase of the aspect ratio. The wetting behavior of pure water of which higher surface energy is extremely complex.
Blue Light Emitting Laser Diodes Based on ZnSe/ZnCdSe Structure Grown by Gas Source Molecular Beam Epitaxy
Authors: Imaizumi Masayuki , Endoh Yasuyuki , Ohtsuka Ken-ichi , Suita Muneyoshi , Toshiro Isu Toshiro Isu , Masahiro Nunoshita Masahiro Nunoshita
Published: October 2002

Diode structure with a (ZnSe/ZnCdSe)5 multiple quantum-well active layer sandwiched between n- and p-ZnSe layers was grown on a (100) GaAs substrate by gas source molecular beam epitaxy using H2Se. Stimulated emission from the diode structure was observed at a wavelength of 486 nm under a pulsed current injection at 77 K. The threshold current density was 1.16 kA/cm2.
Improvement in Optical Transparency of SiC Membrane by Modulating Source Gas Ratio in Chemical Vapor Deposition
Authors: Murooka Ken-ichi , Itoh Masamitsu , Haruki Komano Haruki Komano , Yoshio Gomei Yoshio Gomei
Published: October 2002

A method to improve the optical transparency of a SiC membrane is studied by modulating the source gas carbon-to-silicon ratio (C/Si) during chemical vapor deposition. As a result of an investigation conducted under different C/Si conditions, the optical transparency was found to be highest at C/Si=0.9. Optical transparency decreased at lower C/Si probably due to the increase of surface roughness, and at higher C/Si due to the degradation of crystal quality. By alternate deposition under the condition of C/Si=0.8 and 0.95, the SiC membrane with an optical transparency of 68% was obtained without applying an antireflection coating.
Observation of Magnetic Induction Distribution by Scanning Interference Electron Microscopy
Authors: Takahashi Yoshio , Yajima Yusuke , Masakazu Ichikawa Masakazu Ichikawa , Katsuhiro Kuroda Katsuhiro Kuroda
Published: October 2002

A scanning interference electron microscope (SIEM) capable of observing magnetic induction distribution with high sensitivity and spatial resolution has been developed. The SIEM uses a pair of fine coherent scanning probes and detects their relative phase change by magnetic induction, giving raster images of microscopic magnetic distributions. Its performance has been demonstrated by observing magnetic induction distributed near the edge of a recorded magnetic storage medium. Obtained images are compared with corresponding images taken in the scanning Lorentz electron microscope mode using the same microscope, and the differences between them are discussed.
Field Evaporation of Metal Atoms onto Insulator/Conducting Substrate Using Atomic Force Microscope
Authors: Sumio Hosaka Sumio Hosaka , Hajime Koyanagi Hajime Koyanagi
Published: October 2002

The feasibility of field-evaporating metal atoms onto an insulator/conducting substrate has been investigated. Theoretical and experimental studies clarify that field evaporation is possible in an atomic force microscope (AFM) metal probe/vacuum/thin insulator/conductor configuration. Theoretically, field evaporation is easily achieved on thin SiO2 insulators of less than 100 Å, though image potential and electric field weaken in the presence of an insulating layer. Experiments confirm that ultrasmall gold dots can be formed on a natural SiO2/Si substrate with a threshold voltage of around 10 V. Small dots of 15 nm diameter can be obtained.
Influence of Thermodynamic Factors on Growth of AlAs1-xSbx Alloys
Authors: Wei-Kuo Chen Wei-Kuo Chen , Ming-Ta Chin Ming-Ta Chin
Published: October 2002

Epitaxial layers of AlAs1-
x

Sb

x

have been prepared by metalorganic vapor phase deposition (MOCVD) in a horizontal, atmospheric-pressure quartz reactor. The influences of the V/III ratio and the input partial pressure of trimethylantimony were systematically studied. The experimental results are in good agreement with the calculated ones, based on thermodynamic considerations, which implies that the growth of AlAsSb in MOCVD is controlled predominantly by thermodynamics.
A Four-Terminal GaAs Multiple-Function Transistor with a Buried Silicon-Doping Quantum Well
Authors: Wu Chang-Luen , Hsu Wei-Chou , Shieh Ming-Shang Tsai
Published: October 2002

A four-terminal MESFET-like GaAs multiple-function transistor (MFT) with a buried silicon-doping quantum well has been demonstrated by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The vertical GaAs negative resistance field-effect transistor (NERFET) based on real-space transfer exhibits a high current driving capability, a high peak-to-valley ratio up to 2160, and a high transconductance of 2.1 S/mm at room temperature. In addition, we carried out an ohmic recess to form nonallyed contacts which are electrically isolated from ohmic electrodes. By virtue of nonalloyed ohmic contacts, a planar metal-semiconductor field-effect transistor (MESFET) has been fabricated on the same wafer successfully. The MESFET with a 2×100 µm2 gate exhibits a maximum extrinsic transconductance of 70 mS/mm, a saturation current density of 172 mA/mm, and a Schottky breakdown voltage larger than 15 V at room temperature.
Photorefractive Properties of Ce-Doped Strontium Barium Niobate Single-Crystal Fibers at 830 nm
Authors: Miyagi Masami , Sugiyama Yasuyuki , Hatakeyama Shogo Yagi
Published: October 2002

We have successfully grown strontium barium niobate (SBN) single-crystal fibers doped with up to 0.5 wt% of Ce by the laser-heated pedestal growth method. Their photorefractive properties were investigated systematically as a function of Ce concentration at 830 nm. The diffraction efficiency and two-beam coupling constant both increase with increasing Ce concentration and reach 3.5% and 1.5 cm-1, respectively, at a Ce concentration of 0.5 wt%. The Ce3+ is thought to act as a photorefractive species at near-infrared wavelengths.
Relationship between Azimuthal Surface Anchoring Strength and Chiral Pitch Required for Twisted-Nematic Liquid Crystal Display without Reverse-Twist Domain
Authors: Eung Sang Lee Eung Sang Lee , Tatsuo Uchida Tatsuo Uchida
Published: October 2002

Using circularly rubbed cells, we experimentally and theoretically investigate the required typical energy difference between the left-handed twist and right-handed twist in order to avoid reverse-twist domains in the twisted-nematic liquid crystal display (TN-LCD). We also clarify the relationship between the azimuthal surface anchoring strength and the typical chiral pitch required for obtaining the reverse-twist-domain-free TN-LCD.
Crystallization of Amorphous Silicon by Excimer Laser Annealing with a Line Shape Beam Having a Gaussian Profile
Authors: Jhon Young Min , Kim Dong Hwan , Hong Chu Hong Chu , Sang Sam Choi Sang Sam Choi
Published: October 2002

Amorphous silicon films of 50 mm×50 mm have been crystallized by 1-dimensionally scanning a line shape excimer laser beam with a Gaussian profile in the scanning direction, which basically reduces the nonuniformity of the 2-dimensional scanning method. The laser energy density and substrate temperature were varied. Grains as large as 100 nm with smooth surfaces were obtained with a laser energy density of 300 mJ/cm2with substrate heating of 400°C, where the conductivity was measured to be 9.6×10-6S/cm. Higher energy density increased the grain size and crystallinity but the conductivity decreased due to the separation of grain clusters. Substrate heating was found to considerably increase the grain size and crystallinity.
New Ultrasonic Method to Investigate Flux Pinning Properties of Superconducting Thin Films
Authors: Horie Yuuji , Youssef Ahmed A. A. , Oku Takahiro , Maneki Jyunya , Tsutsui Yutaka , Miyazaki Tomoyuki , Ichikawa Fusao , Fukami Takeshi , Aomine Takafumi
Published: October 2002

A new ultrasonic method has been proposed for the investigation of flux pinning properties of superconducting thin films. In the method, pinned flux lines are excited by the ultrasonic vibration of pinning centers, and depinned flux lines are detected in terms of the flow voltage generated by the Lorentz force due to transport current. By applying a parallel magnetic field and propagating AM ultrasound perpendicularly to the surface of YBa2Cu3O7-δ films, a maximum of AC voltage was observed below the onset temperature of the superconducting transition. From its dependence on the ultrasonic amplitude and the transport current, the observed voltage is found to be induced by flux flow normal to the surface raised by ultrasound.
Characteristics of In0.3Ga0.7As/In0.29Al0.71As Heterostructures Grown on GaAs Using InAlAs Buffers
Authors: Chyi Jen-Inn , Shieh Jia-Lin , Wu Chia-Song , Lin Ray-Ming , Pan Jen-Wei , Lin Yi-Jen Chan
Published: October 2002

Device quality In0.29Al0.71As and In0.3Ga0.7As epilayers have been successfully grown on GaAs substrates using a carefully designed In

x

Al1-
x

As multistage strain-relaxed buffer. Cross-sectional transmission electron microscopy has shown that the misfit dislocations are confined in the lower regions of the metamorphic buffer layer. The Hall electron mobility of the modulation doped structure grown on the InAlAs buffer was 6160 and 25379 cm2/V· s with sheet carrier densities of 1.9×1012 and 1.8×1012 cm-2 at 300 and 77 K, respectively. The excellent characteristics of the field-effect transistors fabricated on this structure have indicated its potential for practical applications.
Crystal Orientations of YBa2Cu3O7-δ Thin Films Grown on LaSrGaO4(100), (001) and SrTiO3(100) Substrates
Authors: Ha Dong Han , Yong Ki Park Yong Ki Park , Jong-Chul Park Jong-Chul Park
Published: October 2002

We have grown YBa2Cu3O7-δ thin films with a self-template on LaSrGaO4(100), (001) and SrTiO3(100) substrates by means of off-axis rf sputtering, and investigated the crystal orientations using X-ray diffraction, polarized Raman and electrical resistivity measurements. YBa2Cu3O7-δ thin film grown on LaSrGaO4(100) substrate has in-plane alignment with the c-axis parallel to the [001] direction of the substrate. The in-plane alignment was observed by X-ray φ-scan measurement. The polarized Raman spectra and anisotropic resistivity ratio ( ρ[001]/ρ[010]) of about 10 at 290 K, however, indicate there is a small fraction of in-plane misalignment. The thin films grown on isotropic SrTiO3(100) and LaSrGaO4(001) substrates do not show any anisotropic property for the two perpendicular directions of the substrates.
Application of Superconducting Films to Fault Current Limiter
Authors: Terashima Yoshiaki , Yamazaki Mutsuki , Kudo Yuki , Yoshino Hisashi , Oshima Ken Ando
Published: October 2002

The applicability of high-T
c-superconducting films to a fault current limiter (FCL) without liquid nitrogen ( L-N2) was investigated. The FCL element consists of a 200-nm-thick YBa2Cu3O7-
X

(YBCO) film having a current-limiting area 4 mm wide and 90 mm long. It is cooled by a refrigerator. When a voltage of 100 V
r
m
s
(150 A) was applied at 77 K, the YBCO film transitioned to a resistive state at 13 A and the current was limited to 7 A in less than 0.5 ms. At lower temperature, 74 K, the transition current increased to more than 30 A, while the limited current remained less than 9 A. Thus, it was considered that a superior FCL system without L-N2 could be obtained.
Superconducting Quantum Interference Device Voltage Swing Related to Additional Positive Feedback Parameters
Authors: Takada Youichi , Uehara Gen , Kado Naoki Matsuda
Published: October 2002

The relationship between superconducting quantum interference device (SQUID) voltage swing and additional positive feedback (APF) parameters has been investigated. Voltage swing is depressed as APF gain increases. In a symmetric-bias-injection SQUID, the voltage depression can be explained by the voltage divider action of APF resistance and the SQUID dynamic resistance. On the other hand, the voltage depression in an asymmetric-bias-injection SQUID is expressed as the effect of the voltage divider action multiplied by the effect of thermal noise of APF resistance. These two effects should be considered when designing SQUIDs with an APF.
Fabrication of Thin-Film p-CdS(Cu)/n-CdSe Heterojunctions and Their Photovoltaic Characteristics
Authors: Kashiwaba Yasube , Atsushi Tada Atsushi Tada , Toshio Ikeda Toshio Ikeda
Published: October 2002

Thin-film p-CdS(Cu)/n-CdSe heterojunction cells were fabricated by all-vacuum-deposition methods. The cells showed rectifying characteristics and photovoltaic effects. There is a remarkable increase of the relative response of the short-circuit current in the spectral region between 510 and 730 nm, which corresponds to the region between the fundamental absorption edges of CdS and CdSe. It was also found that with increasing concentration of copper in the CdS(Cu) layer, the sensitivity of the response increases in the longer-wavelength side. No evidence of the presence of p-type Cu2S was detected in the characteristics of the cells.
Preparation of Bulk YBa2Cu4O8 by a Simple Solid-State Reaction Method
Authors: Xuguang Zheng Xuguang Zheng , Kazuyoshi Hirakawa Kazuyoshi Hirakawa
Published: October 2002

An YBa2Cu4O8 superconductor is synthesized without the use of high-pressure oxygen, reaction-rate enhancer or sophisticated heat treatment. The simple method is characterized by using Y2O3, Ba(NO3)2 and CuI as the starting materials for the solid-state reaction. The X-ray diffraction pattern suggests an almost single YBa2Cu4O8 phase. Resistivity and magnetic susceptibility measurements show a T
c (zero resistance) of 76 K and a T
c (onset) of 83 K characteristic of YBa2Cu4O8.
Noise Characteristics of dc Superconducting Quantum Interference Device with Additional Positive Feedback
Authors: Takada Youichi , Kado Gen Uehara
Published: October 2002

We investigated the flux noise characteristics of a superconducting quantum interference device (SQUID) with additional positive feedback (APF) by comparing calculated results with experimental results. Equations for the minimum flux noise of a SQUID with APF and the optimum condition of APF gain (βa) are deduced. We examined the relationship of flux noise versus βaand experimentally confirmed that it has a minimum point. The deduced equations agree well with experimental results. From the viewpoint of total flux noise of SQUID, it is useful to employ the APF technique for a low-intrinsic-noise SQUID, but not for a high-intrinsic-noise SQUID.
Synthesis of Superconducting T′-(La1-xCex)2CuO4
Authors: Yamada Tomoaki , Kyoichi Kinoshita Kyoichi Kinoshita , Hiroyuki Shibata Hiroyuki Shibata
Published: October 2002

A new preparation method for obtaining superconducting T′-(La1-
x

Ce

x

)2CuO4 is presented. The method consists of three processes: precursor material synthesis, oxidation and T′-phase formation. The single phase has been obtained for 0.065≤x≤0.08. The maximum superconducting onset (T
c(onset)) and zero-resistance (T
c(zero)) temperatures are 30 K and 17 K, respectively, which are obtained when x=0.065. The T
c(onset) obtained here is higher than those of other T′-type cuprates.
O2 Gas Pressure Effects on Surface Morphology in Ferroelectric Bi4Ti3O12 Thin Films Fabricated by Spin-Coating Pyrolysis
Authors: Kakimi Atsushi , Soichiro Okamura Soichiro Okamura , Takeyo Tsukamoto Takeyo Tsukamoto
Published: October 2002

Fabrication of ferroelectric Bi4Ti3O12 thin films was carried out by spin-coating pyrolysis of Bi and Ti naphthenates and successive heat treatments in O2 gas. Heat treatments in O2 gas were effective for fabrication of ferroelectric Bi4Ti3O12 thin films with c-axis orientation. It was confirmed that the film surface morphology strongly depends on the O2 gas pressure. Smooth platelike grains of the size greater than 10×10 µm2 formed extensively in thin films upon heat treatment at the O2 gas pressure of 4.0×105 Pa. The film thickness was 500 nm. The thin film was a single phase of Bi4Ti3O12 completely oriented along the c-axis with good ferroelectric properties at room temperature: coercive field of 15 kV/cm, remanent polarization of 1.9 µC/cm2, dielectric constant of 43 and loss of 0.02.
Hole Burning Spectroscopy of Tertiarybutyl Groups of Tetratertiarybutylphthalocyanine
Authors: Takahashi Jun-ichi , Tsuchiya Jun , Hiroshi Tanaka Hiroshi Tanaka , Kenji Kawasaki Kenji Kawasaki
Published: October 2002

Optical spectra of tertiarybutyl groups substituted into phthalocyanine were investigated by hole burning. A fine structure consisting of at least seven lines was observed in the phonon side hole. The values of the splitting were 1.8±0.3 cm-1 for polyethylene and poly(methyl methacrylate) matrices.
A Novel Super-Resolution Technique for Optical Lithography–Nonlinear Multiple Exposure Method
Authors: Ooki Hiroshi , Masaya Komatsu Masaya Komatsu , Masato Shibuya Masato Shibuya
Published: October 2002

A novel method for optical lithography using a resist with nonlinear photosensitivity and the multiple exposure technique is described. By means of this method, the diffraction-limited optical cutoff frequency is raised markedly, which cannot be realized by any of the other methods proposed previously. A brief explanation of the principle is given and computer simulations are demonstrated.
Optical Properties of Poly(3,4-dialkyl-1,6-phenyleneethynylene)
Authors: Yoshino Katsumi , Kazuya Tada Kazuya Tada , Mitsuyoshi Onoda Mitsuyoshi Onoda
Published: October 2002

A conducting polymer, poly(3,4-dialkyl-1,6-phenyleneethynylene) (PDAPE) has been prepared for the first time and found to be highly soluble in many common solvents such as chloroform and toluene. Band-gap energy as large as 3.1 eV is evaluated in PDAPE films. Corresponding to large band-gap energy, blue light emission has been observed in a light-emitting diode Al/PDAPE/indium-tin-oxide (ITO) fabricated with PDAPE as the light-emitting layer. Unique temperature dependence of optical properties as well as electrochemical characteristics have also been found in PDAPE.
Absolute Density Measurement of a Pulsed H2 Gas Jet Used for Extreme Ultraviolet Generation by Nonlinear Frequency Conversion
Authors: Hirakawa Yasuyuki , Nagai Akifumi , Okada Tatsuo , Maeda Mitsuo , Katsunori Muraoka Katsunori Muraoka
Published: October 2002

A pulsed molecular hydrogen gas jet is an efficient nonlinear medium for generation of extreme ultraviolet radiation via two-photon resonant third harmonic generation or four-wave mixing. The absolute density of hydrogen molecules in the gas jet was measured by comparing the laser-induced fluorescence signal from the jet with that from a gas cell filled with a known density of H2 gas. This information can be used to improve the efficiency of frequency tripling of an ArF laser.
Scanning Tunneling Microscope Fabrication of Atomic-Scale Memory on a Silicon Surface
Authors: Huang Dehuan , Uchida Hironaga , Aono Masakazu
Published: October 2002

By using a scanning tunneling microscope (STM) operated in an ultrahigh vacuum, we can extract single Si atoms from predetermined positions of the Si(111)-7×7 surface through field evaporation. This technique enables us to create specific arrangements of Si vacancies on the surface. Some of the extracted Si atoms can be captured by the tip and redeposited onto the surface. We show that natural Si vacancy defects existing on the surface can be repaired by this technique. These results demonstrate the potential of STM for the construction of atomic-scale data memory.
Parallax Error Correction of a Multilens Camera for Precise Determination of Dynamic Stress Intensity Factor
Authors: Mamoru Kido Mamoru Kido , Kiyoshi Takahashi Kiyoshi Takahashi
Published: October 2002

To improve the accuracy in caustic measurement, the effect of parallax with 30 lenses of a Cranz-Schardin-type camera on the determination of caustic diameter D was experimentally evaluated using a single-edge-notch-type model specimen. Correction factors for the transverse diameter of caustics on an image plane were obtained. These factors were taken into account in the determination of the velocity effect on the dynamic stress intensity factor K
ID of PMMA during fast crack propagation. It is shown that the hysteresis in the K
ID-\dota curves was similar for larger and smaller initial curves except at velocities higher than 400 m/s.
A Novel Birefringent Distributed Bragg Reflector Using a Metal/Dielectric Polarizer for Polarization Control of Surface-Emitting Lasers
Authors: Mukaihara Toshikazu , Ohnoki Noriyuki , Baba Toshihiko , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga
Published: October 2002

We propose a novel polarization control structure in vertical cavity surface-emitting lasers using a birefringent metal/dielectric polarizer terminating a distributed Bragg reflector (DBR). Polarization-dependent reflectivity at the resonant wavelength is theoretically predicted by adjusting the phase condition in the DBR. An experimental result shows a reflectivity difference for two polarization states. The possibility of polarization control as well as polarization switching is suggested.
Amplitude and Frequency Stabilization of a cw Nd:YAG Ring Laser
Authors: Katsuyuki Kasai Katsuyuki Kasai , Mitsuo Ishizu Mitsuo Ishizu
Published: October 2002

We have developed a single-frequency cw Nd:YAG ring laser for the generation of squeezed light. Both the amplitude and frequency of the laser are stabilized. An acousto-optic modulator removes the intensity fluctuation with the first-order diffracted beam for the amplitude stabilization. The laser frequency is locked to a resonant reference cavity by using the dithering technique. Amplitude stability better than 0.1% and frequency stability of 160 kHz rms are obtained with output power over 2 W at 1.064 µ m.
Preparation and Oxidation of Metallofullerenes Containing Praseodymium
Authors: Ishibashi Masayoshi , Yasushi Tomioka Yasushi Tomioka , Yoshio Taniguchi Yoshio Taniguchi
Published: October 2002

Metallofullerenes containing praseodymium (Pr) were prepared by contact-arc vaporization of a graphite/ Pr2O3 composite rod. In addition to the pure fullerenes, a series of stable monopraseodymium-fullerene complexes such as PrC60, PrC74 and PrC82 were observed by mass spectrometry. In soot kept in air for eight months, metallofullerene oxide, PrC82O, was also observed. The intensity ratio of PrC82O to PrC82 was found to be larger than that of C60O to C60. This suggests that the PrC82 is more easily spontaneously oxidized than the pure fullerenes, due to its charge-transfer structure.
Self-Organization of Boxlike Microstructures on GaAs (311)B Surfaces by Metalorganic Vapor-Phase Epitaxy
Authors: Nötzel Richard , Jiro Temmyo Jiro Temmyo , Toshiaki Tamamura Toshiaki Tamamura
Published: October 2002

We have found new self-organizing phenomena in metalorganic vapor-phase epitaxy of strained InGaAs/AlGaAs heterostructures on GaAs (311)B substrates. During growth interruption, strained InGaAs films naturally arrange into well-ordered arrays of nanoscale disks direclly covered with AlGaAs. This self-organization has been observed in neither GaAs growth on (311)A substrates nor InGaAs growth on conventional (100) substrates. The disk diameter is controlled by the In content from 150 nm to 30 nm. These results clearly indicate that the strain energy of InGaAs films combined with the surface migration on (311)B surfaces causes the ordering of the microdisks. For the first time, our quantum-boxlike structures exhibit optical properties at room temperature comparable to conventional quantum wells.
Reactive Ion Etching of BiSrCaCuO Superconducting Thin Films using Ethane and Oxygen
Authors: Oishi Toshiyuki , Takami Tetsuya , Kuroda Ken'ichi , Kojima Kazuyoshi , Wada Osamu , Masahiro Nunoshita Masahiro Nunoshita
Published: October 2002

Reactive ion etching (RIE) of Bi2Sr2Ca2Cu3O

x

superconducting thin films was performed using ethane and oxygen. As for the etched surface morphology, no degradation was observed as compared with that before etching. The zero resistivity temperature for the samples etched by RIE was the same as that of the as-grown sample. Another feature of this etching was a maximum selectivity of 50 against MgO substrates.
Novel Preparation Method of Metal Particles Dispersed in Polymer Films and Their Third-Order Optical Nonlinearities
Authors: Ogawa Shuichiro , Hayashi Yoshio , Kobayashi Norio , Tokizaki Takashi , Nakamura Arao
Published: October 2002

Polymer films containing nanometer-sized particles of Ag or Au were prepared by a simple process based on the reduction of organometallic compounds in a polymer matrix. Films were formed by casting a polymer solution admixed with an organometallic compound and a reducing agent onto a substrate. Third-order optical susceptibilities, χ(3), of these films were measured to be 2×10-9 esu for Ag and 1×10-8 esu for Au.
Optical Damage Resistance of LiNbO3 Thin-Film Optical Waveguides Grown by Liquid-Phase Epitaxy
Authors: Kondo Yukiko , Kouyama Tatsuya , Ohno Kazushige , Tsuji Masahiro , Nakamura Masanori , Yoichi Fujii Yoichi Fujii
Published: October 2002

Waveguides of 5 mol% MgO-doped lithium niobate thin film are grown on a LiTaO3 substrate by liquid-phase epitaxy. The photorefractive sensitivity of the thin-film LiNbO3 waveguides using the Li2O-V2O5 flux and that of waveguides using Li2O-B2O3 flux are quantitatively measured and compared. The MgO-doped LiNbO3 thin-film waveguides grown using the Li2O-B2O3 flux are proven to be much more resistant to optical damage than those grown using the Li2O-V2O5 flux.
Zn-Related Donor-Acceptor Pair Emission in CuAlSe2 Epitaxial Layers
Authors: Shirakata Sho , Chichibu Shigefusa , Matsumoto Satoru , Shigehiro Isomura Shigehiro Isomura
Published: October 2002

Photoluminescence (PL) studies have been carried out on the intense blue-green emission at 2.51 eV observed at low temperature (8 K) in Zn-doped CuAlSe2 epitaxial layers grown on GaAs by means of the low-pressure metal-organic chemical vapor deposition technique. Based on the analyses of the dependences of PL spectra on excitation intensity, decay time and temperature, this emission is interpreted as donor-acceptor pair recombination involving a donor with activation energy of 0.11 eV and an acceptor with activation energy of 0.23 eV.
Photoluminescence Quenching under Reverse Bias in Organic Multilayer Structure Utilizing 8-Hydroxyquinoline Aluminum and Aromatic Diamine
Authors: Fujii Akihiko , Ohmori Yutaka , Chikayoshi Morishima Chikayoshi Morishima , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Photoluminescence intensity from an organic multilayer structure utilizing 8-hydroxyquinoline aluminum ( Alq3) and aromatic diamine (TPD) has been modulated by applying reverse bias voltage. Photoluminescence intensity decreases with increasing reverse bias voltage. The decrease of photoluminescence intensity is enhanced in the thinner multilayer structure compared with the thicker multilayer. The mechanism of photoluminescence quenching in the organic multilayer structure has been discussed.
Photoacoustic Signals from Ion-Implanted and Epitaxially Grown Layers on Silicon Substrate
Authors: Ikari Tetsuo , Kouji Maeda Kouji Maeda , Koji Futagami Koji Futagami
Published: October 2002

A nonradiative transition in ion-implanted and epitaxially grown layers on a Si substrate was measured by a piezoelectric photoacoustic (PA) spectroscopy. It is considered that the observed peak at 1.07 eV is caused by a nonradiative recombination of optically excited electrons from boron acceptor levels. The decrease of the 1.07 eV peak intensity by ion implantation is considered to be due to the formation of a surface damaged layer with deep defect levels. The PA spectra of epitaxially grown samples are well explained by summing the spectra of p- and n-type bulk samples. The electric field at the p-n junction may be effective in the PA signal generation mechanism in the higher photon- energy region.
Dielectric Hysteresis Loop in Alicyclic and Aromatic Polyamides
Authors: Murata Yukinobu , Tsunashima Kenji , Koizumi Naokazu
Published: October 2002

The relationship between electric displacement D and electric field E was studied for alicyclic polyamides of 1,3-bis(aminomethyl)cyclohexane and adipic, pimelic and sebacic acids, an aromatic polyamide prepared from hexamethylenediamine (HMD) and isophthalic acid and a copolyamide of HMD with isophthalic and terephthalic acids. Quenched samples of these polyamides were poorly crystalline or amorphous and exhibited a D-E hysteresis loop with the remanent polarization of 26 to 38 mC·m-2. The remanent polarizations disappeared at the glass transition temperature of each sample. The origin of the D-E hysteresis loop is attributable to amide groups in amorphous regions.
Excimer Laser Ablation of Cryogenic NO2 Films
Authors: Sekine Shigeyuki , Ichimura Shingo , Hazime Shimizu Hazime Shimizu , Hiroko Hashizume Hiroko Hashizume
Published: October 2002

Cryogenic NO2 films were ablated by a XeCl excimer laser. Only NO2 molecules were detected by a time-of-flight method. Velocity distribution of ablated NO2 molecules was found to be almost thermal. The derived temperature of the fitted Maxwell-Boltzmann distributions depended on the thickness of cryogenic NO2 film in the range from 300 K to 1100 K. The fastest NO2 observed in the present experiment had a translational energy of 0.5 eV.
Organometallic Vapor Phase Epitaxial Growth of AlAsxSb1-x Films Using Tertiarybutylarsine
Authors: Chen Wei-Kuo , Jehn Ou Jehn Ou , Wei-I Lee Wei-I Lee
Published: October 2002

The deposition of AlAs

x

Sb1-
x

films is studied systematically using an organometallic vapor phase epitaxy growth technique. It is found that the growth of AlAsSb films requires a low V/III ratio to enhance the incorporation of antimony into the solid. The composition of the alloy also depends strongly on the growth temperature. Experimental data shows that films grown at higher temperatures yield much higher AlSb contents in the AlAs

x

Sb1-
x

alloys. This is contrary to the results reported for GaAsSb films. In our study, we are able to grow metastable AlAs

x

Sb1-
x

epitaxial films throughout the entire range of the solid composition for temperatures above 550° C.
Improved Surface Smoothness of YBa2Cu3Oy Films and Related Multilayers by ArF Excimer Laser Deposition with Shadow Mask “Eclipse Method”
Authors: Kinoshita Kazuya , Hiroshige Ishibashi Hiroshige Ishibashi , Takeshi Kobayashi Takeshi Kobayashi
Published: October 2002

By simply placing a shadow mask between the target material and substrate, the particle (or droplet) problem peculiar to the excimer laser deposition technique was completely eliminated. It is tentatively called the “ eclipse method”, in which the deposition proceeds through only diffusion. Mirrorlike YBa2Cu3O

y

thin films with T
c as high as 90–93 K were obtained reproducibly by (eclipse) ArF excimer laser ablation on MgO substrates in 0.3 Torr O2 ambient. The growth rate reduction was only 70% under this ambient condition. Even when the pressed-powder targets were employed for deposition, the metal-insulator-superconductor (MIS) layered structure seldom encountered the pinhole problem.
A New Method for Measuring the Azimuthal Anchoring Energy of a Nematic Liquid Crystal
Authors: Iimura Yasufumi , Norihiko Kobayashi Norihiko Kobayashi , Shunsuke Kobayashi Shunsuke Kobayashi
Published: October 2002

We have proposed a new optical method for measuring the twist angle of twisted nematic cells, and the method has been applied to obtain the azimuthal anchoring energy for a nematic liquid crystal. The method is based on a modulation in the polarization state of an incident probing laser beam to the sample cells, and the resulting transmitted intensity of the beam is theoretically analyzed through the 2×2 Jones matrix method. The obtained anchoring energy for the azimuthal distortion is about 1.5×10-5 J/m2 for a polyvinylalcohol alignment film; which is about two orders of magnitude lower than that for the corresponding polar anchoring energy.
Effects of Oxygen Added to Reagent Gas on Chemical Vapor Deposition of Diamond Thin Films
Authors: Tae-Hyun Kim Tae-Hyun Kim , Takeshi Kobayashi Takeshi Kobayashi
Published: October 2002

The microwave-plasma-assisted chemical vapor deposition (CVD) of diamond film with ( H2+CO+O2) gaseous source revealed increasing net growth rate with O2 addition up to 0.5%, although the etching rate itself markedly increased with O2. To understand the effect of oxygen on CVD, we have proposed a possible model for diamond surface reaction, a modified Harris model [Appl. Phys. Lett. 56 (1990) 2298], by taking into account the forced hydrogen abstraction from the surface structure associated with chemical reaction with OH species. Our model, though still slightly rough, explained to a certain extent the observed increase in the diamond growth rate upon oxygen addition.
Mie-Scattering Ellipsometry for Analysis of Particle Behaviors in Processing Plasmas
Authors: Yasuaki Hayashi Yasuaki Hayashi , Kunihide Tachibana Kunihide Tachibana
Published: October 2002

In-process Mie-scattering ellipsometry has been newly developed. The refractive index of the particles and the spread of particle size distribution, as well as the mean particle size and the density, can be evaluated by the method. As a demonstration, the behavior of carbon particles injected into argon plasma was observed. It was suggested from the analyzed results that the size of carbon particles increased through coagulation in argon plasma, the geometric standard deviation of the size distribution was about 1.5, and the coagulated particles have smaller refractive index than evaporated carbon.
Liquid Metal Ion Sources: Normalization of Virtual Source Size and Angular Ion Intensity
Authors: Ishitani Tohru , Umemura Kaoru , Kawanami Yoshimi
Published: October 2002

Normalization of liquid metal ion source (LMIS) features such as angular ion intensity and virtual source size has been proposed. The derived form for the normalized angular ion intensity is verified by the experimental data for Ga, Ga–In, Ga–In–Sn, and Cs LMISs.
In Situ Measurements of Water Immersion and UV Irradiation Effects on Intensity and Blue Shift of Visible Photoluminescence in Porous Si
Authors: Baba Mamoru , Kuwano Gou , Tadashi Miwa Tadashi Miwa , Hiroshi Taniguchi Hiroshi Taniguchi
Published: October 2002

It has been found byin situmeasurements that immersion in deionized water and simultaneous uv irradiation of porous silicon can cause a considerable change in emission intensity and a blue shift in visible (yellow) photoluminescence. It was determined that the blue shift is mainly due to reduction in size and surface alteration by oxidation of porous Si and that an initial increase and subsequent decrease in intensity is due to competition between surface passivation and generation of nonradiative recombination centers by the oxidation. After prolonged irradiation, a new blue emission was observed in place of the yellow emission. Excitation spectra for the yellow photoluminescence were also investigated.
Radial Distribution of Oxygen Precipitates in Czochralski Silicon Single Crystals
Authors: Sasaki Hitoshi , Kadoi Mikio , Furuya Hisashi , Shimanuki Takayuki Shingyouji
Published: October 2002

The effect of annealing conditions on the radial distribution of oxygen precipitates in Czochralski (CZ) silicon crystals was examined through two-step annealing. When the preannealing temperature was lower than 800°C, the oxygen precipitation depended on the initial oxygen concentration, and precipitation near the periphery of the crystal was often suppressed. When the preannealing temperature was higher than 900°C, the oxygen precipitation was enhanced near the periphery. This result indicates that extremely stable nuclei, whose density is low compared with the total amount of nuclei, exist near the periphery of the CZ crystals.
New High-Tc Superconductor Family of Cu-Based Cu1-xBa2Can-1CunO2n+4-δ with Tc>116 K
Authors: Ihara Hideo , Tokiwa Kazuyasu , Ozawa Hirotomo , Hirabayashi Masayuki , Negishi Akira , Song Hirofumi Matuhata
Published: October 2002

A new high-temperature and nontoxic superconductor family of Cu
1-x
Ba2Ca
n-1
Cu
n
O2n+4-δ with critical temperature (T
c)>116 K was discovered. These materials were prepared by the high-pressure technique. A superconductor sample with the highest T
c contains mainly a Cu1-
x

Ba2Ca3Cu4O12-δ phase. The T
c value of the Cu1-
x

Ba2Ca3Cu4O12-δ phase is 116.4 K. The phase has two kinds of tetragonal structures: body-centered tetragonal (bct) and simple tetragonal. The lattice parameters of bct are a=7.7114 Å and c=35.986 Å. The disordering or full occupation of Cu-vacancy sites leads to the simple tetragonal phase with the space group of P4/mmm and the half values of the lattice constants (a=3.8557 Å and c=17.993 Å) of the bct phase.
  The relationship between the lattice constant c and the number of CuO2 layers n is c/2=8.4+3.2(n-1) ( Å). The small CuO2-block spacing (8.4 Å) of this family suggests a lower anisotropy and higher J
c than in Hg- and Tl-based superconductor families.
Hydrogen-Absorption Effect on YBa2Cu3Ox
Authors: Kebukawa Takeji , Kumaki Yoshitaka , Fujiwara Katsuyuki , Tatsumi Yukichi , Taimatsu Hitoshi , Kaneko Hiroyuki
Published: October 2002

Hydrogenated samples of YBa2Cu3O

x

′
H

y

were prepared by allowing an oxide superconductor YBa2Cu3O

x

to absorb hydrogen. From magnetization measurements, it was shown that the critical temperature increased from 91.8 K to 94.2 K for 0≤y≤0.3 and decreased from 94.0 K to 91.9 K for 0.4≤y≤1.4. The iodometric titration indicated that an average valence number of copper decreased linearly with increasing hydrogen content. The hydrogenated samples displayed superconductivity above 90 K even when the average valence number of copper was below 2.0. Consequently it was concluded that the oxygen content remained at its initial value of 6.98 even though the oxide superconductor had absorbed hydrogen.
Flip-Flop and Oscillating Behavior Obtained with Serial Connection of Liquid Crystal Bistable Optical Device Pixels
Authors: Toshiaki Nose Toshiaki Nose , Susumu Sato Susumu Sato
Published: October 2002

An easily operated and compact liquid crystal bistable optical device (LCBOD) can be obtained by adopting internal optical feedback. Since the structure of the pixel is quite simple, it is easy to connect pixels in series. When 2 pixels are connected to have a common feedback loop, a flip-flop behavior with complementary ON-OFF properties can be obtained. In case of the connection of 3 pixels, a well-regulated oscillating behavior can be observed and the three oscillating waves of transmitted light intensity are shifted one-third of the oscillating period relative to each other. The waveform and period are investigated for various voltage levels.
Low-Temperature Metalorganic Vapor Phase Epitaxial Growth of CuAlxGa1-x(SySe1-y)2
Authors: Yamamoto Masahiro , Ogawa Takeshi , Hara Kazuhiko , Yoshino Hiroshi Kukimoto
Published: October 2002

CuAl

x

Ga1-
x

(S

y

Se1-
y

)2 quaternary and pentanary alloy layers, lattice-matched with GaP, have been successfully grown by metalorganic vapor phase epitaxy at substrate temperatures of 450–500°C, which could not be achieved previously at 600°C. The quality of layers in terms of crystallinity and luminescence properties has been improved by lowering the growth temperature. The growth over a wide range of Al composition has been demonstrated; photoluminescence over the yellow to violet spectral region can be obtained without changing the lattice parameter.
Double RF System for Suppression of Longitudinal Coupled Bunch Instability on UVSOR Storage Ring
Authors: Kazuhiro Tamura Kazuhiro Tamura , Toshio Kasuga Toshio Kasuga , Makoto Tobiyama Makoto Tobiyama , Hiroyuki Hama Hiroyuki Hama , Goro Isoyama Goro Isoyama , Toshio Kinoshita Toshio Kinoshita
Published: October 2002

A third-harmonic cavity has been installed on the UVSOR electron storage ring in order to suppress longitudinal coupled bunch instability with a double RF system. The bunch length and the frequency spread of the synchrotron oscillation were increased with the double RF system, and the measured values at a low beam current were consistent with calculated ones. The longitudinal coupled bunch instability has been perfectly damped by Landau damping at the beam current of at least up to 300 mA.
Double-Pass Amplification in Ge Soft X-Ray Laser with a Polarizing Half-Cavity
Authors: Murai Kensuke , Yuan Gang , Kodama Ryosuke , Daido Hiroyuki , Kato Yoshiaki , Niibe Masahito , Miyake Akira , Tsukamoto Masami , Fukuda Yasuaki , Neely David , Andrew Macphee Andrew Macphee
Published: October 2002

The control of polarization of soft X-ray lasers is presented. Double-pass amplification in a soft X-ray laser with a half-cavity comprising a multilayer polarizer and a normal incidence reflector has been tested. Successful results have been obtained using a curved-slab target for the lasing line at 19.6 nm due to the J=0–1 transition of the collisional-excitation neonlike germanium soft X-ray laser.
Study of a Veil Structure and a Two-Step Corrosion Suppression Process in Al–Si–Cu Etching
Authors: Sakuma Kazuhito , Shoji Yagi Shoji Yagi , Kazuo Imai Kazuo Imai
Published: October 2002

µ-Auger analysis of the veil structure produced during Al–Si–Cu etching indicates the presence of carbon, oxygen, aluminum, and chlorine in all regions of the structure and silicon in the outer region. A novel two-step etching method deyeloped based on the veil-structure analysis can suppress corrosion when using CF4, and O2+CF4 gas plasma. This method drastically decreases the corrosion density.
Optically Pumped Stimulated Emission from CuGa(S0.65Se0.35)2/CuAl0.3Ga0.7(S0.65Se0.35)2 Double Heterostructure Grown by Metalorganic Vapor Phase Epitaxy
Authors: Yamamoto Masahiro , Ogawa Takeshi , Hara Kazuhiko , Yoshino Junji , Hiroshi Kukimoto Hiroshi Kukimoto
Published: October 2002

We report, for the first time, stimulated emission induced by optical pumping at 77 K in CuGa(S0.65Se0.35)2/CuAl0.3Ga0.7(S0.65Se0.35)2 double heterostructures fabricated by metalorganic vapor phase epitaxy. The laser operation occurred at 592 nm above the threshold excitation intensity of 192 kW/cm2. Refractive indexes of the constituent layers of CuGa(S

y

Se1-
y

)2 and CuAl

x

Ga1-
x

(S

y

Se1-
y

)2 were also determined experimentally.
ZnCdSe/ZnSe/ZnMgSSe Separate-Confinement Heterostructure Laser Diode with Various Cd Mole Fractions
Authors: Itoh Satoshi , Nakayama Norikazu , Ohata Toyoharu , Ozawa Masafumi , Okuyama Hiroyuki , Nakano Kazushi , Ikeda Masao , Akira Ishibashi Akira Ishibashi , Yoshifumi Mori Yoshifumi Mori
Published: October 2002

Room temperature pulsed operation of ZnCdSe/ZnSe/ZnMgSSe separate-confinement heterostructure (SCH) lasers has been achieved in a wavelength range from 485.7 to 521.6 nm. We have achieved shorter wavelength blue at room temperature than thus far reported. A decrease in threshold current density J
th and a increase in the slope efficiency for ZnCdSe/ZnSe/ZnMgSSe SCH laser diodes were observed as the energy difference between the active and cladding layers was increased. We determined that more than 0.35 eV for ΔE
g is necessary in order to suppress the carrier overflow. A high characteristic temperature T
0 of 217 K was achieved for a laser diode with ΔE
g of 0.40 eV.
Fabrication of Vertical and Uniform-Size Porous InP Structure by Electrochemical Anodization
Authors: Toshiyuki Takizawa Toshiyuki Takizawa , Shigehisa Arai Shigehisa Arai , Masafumi Nakahara Masafumi Nakahara
Published: October 2002

A vertical porous InP structure with an aspect ratio larger than 100 was obtained by electrochemical anodization of a <111>A-oriented n-InP substrate with HCl etchant. The photoluminescence spectrum of this porous InP showed less surface recombination as well as a slight blue shift attributed to the quantum-size effect. By initiating the etching through SiO2-defined mask windows, which were prepared by electron-beam direct writing along 3 crystalline directions, a uniformly sized (around 72% within the permissible fluctuation error of about 4 nm against 100-nm-sized triangles), high-density (around 50%) structure was fabricated for the first time. These results reveal that this process is very attractive for the fabrication of high-density and low-size-fluctuation quantum-wire and -box structures.
Stability of an Umbilical Director Field of Nematic Liquid Crystal in a Closed Conical Cavity
Authors: Jong-Guang Wei Jong-Guang Wei , Shu-Hsia Chen Shu-Hsia Chen
Published: October 2002

This letter studies the stability of a single umbilical director field of nematic liquid crystal (NLC) in a closed cavity with external electric field. To form the single umbilic structure, we filled NLC with negative dielectric anisotropy in a closed conical cavity and made molecules align perpendicular to the cavity wall. Electric field was applied along the symmetry axis of the cavity. Using the continuum theory, we show that an umbilical director field will transform to a director field of a hyperbolic singular point with disclination ring instead of a Poincaré structure at a critical voltage.
Observations of the Ferroelastic Domain Structure of MP5O14 (M: La–Tb) by means of Scanning Tunneling Microscope, Electron Spin Resonance and X-Ray Diffraction
Authors: Kobayashi Tadashi , Takei Iwao , Katsuda Hiratoshi , Nakamura Shizuo , Yamana Kazuo , Machida Mitsuo
Published: October 2002

The ferroelasticity of rare earth pentaphosphate, MP5O14 (M: La-Tb) belonging to the species mmmF2/m is studied by scanning tunneling microscope (STM), electron spin resonance (ESR) and X-ray diffraction. The temperature dependence (from room temperature to 180°C) of ferroelastic domain structure and monoclinic β angle of EuP5O14 was obtained by STM and X-ray diffraction (ω scan technique). The spin Hamiltonian parameters of LaP5O14:Cr3+ at 150°C in the para phase obtained from the ESR spectra are g

x
= g

y
= g

z
=1.97, D = 0.45 cm-1 and E = 0.05 cm-1. The principal axes of one of the Cr3+ paramagnetic centers are given by the Eulerian angles φ=15°, θ=90° and ψ= 0°.