bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Spin Resonance Microscopy by Localized Magnetic Field Modulation
Authors: Miki Toshikatsu , Ikeya Motoji
Published: November 2005

We have developed an electron spin resonance (ESR) microscope which utilizes a localized magnetic field modulation. The device consists of a conventional ESR spectrometer, a tiny coil for localized field modulation and a mechanism for scanning the modulation field. A two dimensional image associated with the spin distribution at the surface is obtained by the phase-sensitive detection of modulated signals. The resolution does not depend on the linewidth of ESR signals but on the geometry of the coil. The principle and device configuration are presented along with representative data of two dimensional ESR imaging.
Properties of Ion-Beam-Sputtered Ni/Fe Artificial Lattice Film
Authors: Nagai Yasuhiro , Senda Masakatsu
Published: November 2005

This paper reports the results of experimental investigations into the physical and magnetic properties of Ni/Fe artificial lattice films. Through a structure analysis of Ni/Fe lattice films, it is found that the Fe layer has poor crystallinity and the Ni layer has a face-centered cubic structure with strong preferred orientation. Additionally, it is known that the Ni/Fe lattice film acquires good soft-magnetic properties with small coercivity and uniaxial anisotropy as the lattice period is decreased. Saturation magnetization and magnetostriction are confirmed to be controlled by changing the lattice period and the thickness of Ni and Fe layers.
Infrared Active Phonons in (La1-xSrx)2CuO4
Authors: Sugai Shunji
Published: November 2005

Lattice vibrations in (La1-x
Sr
x
)2CuO4 (x=0-0.1) and oxygen deficient La2CuO4 are investigated by infrared reflection spectroscopy. Holes generated by the substitution of Sr and electrons generated by the oxygen deficiency cause a similar change in the infrared spectra. On the assumption of very good two dimensionality, this change is interpreted as the screening of the electric field accompanying the infrared active phonons with polarization in the basal plane. The phonon modes are tentatively assigned.
Single Crystal Growth of Ba2NdCu3O7-δ from BaCO3-Nd2O3-CuO Solution
Authors: Katsui Akinori , Hidaka Yoshikazu , Ohtsuka Hideaki
Published: November 2005

Four to five mm square Ba2NdCu3O7-δ single-crystal plates were grown by slow cooling of a CuO-rich BaCO3-Nd2O3-CuO solution maintained at 1000 to 1200°C. Thin platelets and cube-like crystals of mm size were also prepared. This crystal size improvement is attributed to the fact that Ba2NdCu3O7-δ has the highest thermal stability among superconducting oxides Ba2RCu3O7-δ (R=Y and lanthanoids).
Electron Irradiation Effects on Zinc Oxide Varistors
Authors: Izumiya Toshihide , Miyauchi Shigeaki , Yamamoto Ryoichi , Doyama Masao
Published: November 2005

Multicomponent zinc oxide varistors were electron irradiated and the changes of electrical properties were measured. The electron beam energies were 800 keV, 1 MeV and 2 MeV. In the pre-breakdown region leakage current increased and the activation energy decreased. This degradation was symmetrical with respect to the applied field. In the breakdown region the nonlinear exponent decreased greatly and the breakdown voltage also decreased slightly. These results indicate that defects created by electron irradiation cause the increase of donor concentration, which lowers the activation energy of the thermionic emission. The degradation by 800 keV electron beam is the greatest and the difference between 1 MeV and 2 MeV is very small.
Dislocations in an Al-Mn-Si Icosahedral Quasicrystal Observed by High-Resolution Electron Microscopy
Authors: Hiraga Kenji , Hirabayashi Makoto
Published: November 2005

We report for the first time experimental evidence for the existence of dislocations in an Al-Mn-Si icosahedral quasicrystal. By many-beam electron microscopy, the Burgers vectors on the plane perpendicular to the five-fold symmetry axis have been determined as the displacement of lattice planes or bright-dot alignments around the dislocation cores. The observed results are briefly discussed in comparison with a theoretical prediction by Levine et al.
Valence Study of Orthorhombic and Tetragonal Ba2YCu3Oy: The Role of Oxygen Vacancies in High-Tc Superconductivity
Authors: Oyanagi Hiroyuki , Ihara Hideo , Matsubara Toshiya , Tokumoto Madoka , Matsushita Tadashi , Hirabayashi Masayuki , Murata Keizo , Terada Norio , Yao Takafumi , Iwasaki Hiroshi , Kimura Yoichi
Published: November 2005

The valency of Cu ions in the orthorhombic and tetragonal phases of high-T
c superconductor Ba2YCu3O
y
(6.22<y<6.96) has been studied by near-edge X-ray absorption spectroscopy. The results indicate that the Cu valency at Cu1 sites on the z=1/2 plane is strongly correlated with the high-T
c (90 K) superconductivity, while the Cu valency of Cu2 sites on the basal planes affects the low-T
c (50-60 K) superconductivity of the orthorhombic phase.
Strain-Induced Shift of Optical Phonon Frequency in InGaP Layers Grown on GaAs Substrates
Authors: Kato Takamasa , Matsumoto Takashi , Hosoki Mitsuru , Ishida Tetsuro
Published: November 2005

Raman spectra from InGaP epitaxial layers grown on GaAs (001) and (111)B substrates were studied. Both LO and TO phonon frequencies varied, not only with the alloy composition, but also with the lattice strain induced by the lattice mismatch between the epitaxial layer and the substrate. The amounts of these frequency variations agreed with the calculations, including a two-dimensional elastic strain in the epitaxial layer.
Heterojunctions Obtained Using Semiconducting Metal Sulfide-Polymer Composite Films
Authors: Kubota Etsuo , Yamamoto Takakazu
Published: November 2005

Heterojunctions were prepared using transparent organosols containing colloidal metal sulfide and polymer. For example, spreading of an N,N-dimethylformamide (DMF) organosol containing colloidal cadmium sulfide and an 80:20 copolymer of vinylidene chloride and acrylonitrile on a copper sulfide substrate and removing DMF under vacuum gave a heterojunction which showed rectification of electric current (rectification ratio=44). Preparation of other heterojunctions and their rectification effect are also reported.
High Average Power Nd:Gd3Ga5O12 Slab Laser
Authors: Hayakawa Hirohiko , Maeda Kazuo , Ishikawa Toshiaki , Yokoyama Takeshi , Fujii Yoshimasa
Published: November 2005

A Nd-doped Gd3Ga5O12(GGG) slab laser in normal pulsed operation at 1.06 µm is described. At the pulse repetition rate of 10 pps and pulse duration of 3 ms, the maximum output power was 230 W, and the slope efficiency was 2.4%. No remarkable decrease of slope efficiency was observed between 1 pps and 10 pps. The instability of the laser resonator is discussed with reference to the Mach-Zehnder interferograms under pumping.
Characterization of Epitaxially Grown Semiconductive Layers by Scattering of Optical Pseudo-Surface Waves and Interference Fringes due to Guided Waves within the Layers
Authors: Ogawa Tomoya
Published: November 2005

When optical pseudo-surface waves are generated by a nearly critical transmission condition, their scattering is very useful for observation of defects, such as dislocations and microcracks near surfaces and also for detection of scratches and dust on the surfaces. Guided waves created by multiple reflections between interfaces make equal-thickness fringes by which fluctuation of their thickness is observed.
Low-Temperature Structure in La1.85Sr0.15CuO4
Authors: Kamigaki Kousei , Sano Naokatsu , Terauchi Hikaru
Published: November 2005

Research on the crystal structure of a single crystal of La1.85Sr0.15CuO4-δ was performed at low temperatures by X-ray diffraction technique. New structural phase transitions were found above T
c. Lowering the temperature, the (200) reflection peak splits into three peaks along the [010] direction at T
1∼220 K; on further cooling, these peaks split into several peaks at T
2∼145 K. The crystal structures of the new phases are discussed.
Measurement of RF Superconductivity in YBa2Cu3O7-x with the Standing-Wave Method at 9 GHz
Authors: Tateno Jun , Masaki Norio
Published: November 2005

RF properties of superconducting YBa2Cu3O7-x
were measured with the standing-wave method in the microwave region. The power absorption (Joule loss) of the powder specimen, calculated from the data of the voltage standing-wave ratio (VSWR), changes markedly at the transition temperature, and decreases with decreasing temperature in the superconducting state. In a lower temperature region, it tends to the formula A=17.6 exp (- 0.031 eV/ kT). Microwaves were found to penetrate considerably into the superconducting specimen.
Optical Third-Harmonic Generation from Highly Oriented Polydiacetylene Thin Films Deposited by Vacuum Deposition
Authors: Tomaru Satoru , Kubodera Kenichi , Kurihara Takashi , Zembutsu Sakae
Published: November 2005

Third-harmonic generation measurements are made on highly oriented polydiacetylene thin films fabricated by vacuum deposition. The thin films are obtained by controlling vacuum deposition conditions. The anisotropy of third order optical nonlinear susceptibility for the films was evaluated by measuring the intensity of third-harmonic generation. The susceptibilities along and across the π-conjugated polymer chain are evaluated to be χ(3)=1.1×10-11 esu and χ(3)<10-12 esu at 1.9 µm wavelength, respectively.
Small Nb/Al-Oxide/Nb Josephson Junction Fabrication Using Lift-Off Processes
Authors: Yuda Masahiro , Kuroda Ken'ichi , Nakano Jun'ichi
Published: November 2005

A lift-off technique is applied to the fabrication of all-refractory Nb/Al-oxide/Nb Josephson tunneling junctions. It is found that the lift-off is very efficient for lowering the influence of stresses in refractory metal electrode on junction characteristics. Small junctions (1 µm) with low leakage current can be fabricated by lift-off technique, whereas an etching process increases leakage currents of small junctions. Current-voltage characteristics of Vm=25 mV at a current density of 10 kA/cm2 and a junction current standard deviation of 3.2% in 1 µm size junctions are obtained.
Superconducting Properties of Orthorhombic LaBa2Cu3Oy
Authors: Maeda Atsutaka , Yabe Tomoaki , Eisaki Hiroshi , Uchinokura Kunimitsu , Tanaka Shoji
Published: November 2005

The upper and lower critical fields of orthorhombic LaBa2Cu3O
y
were measured, and superconducting parameters were derived. From these measurements, LaBa2Cu3O
y
was found to be a typical type-II superconductor with extremely short coherence length of 20 Å. Also, taking account of the measured normal-state parameters, both superconducting and normal-state properties in LaBa2Cu3O
y
were found to be almost the same as those in LaBa2Cu3O
y
.
Superconducting and Magnetic Properties of High-Tc Superconductor GdBa2Cu3Ox
Authors: Kohara Takao , Oda Yasukage , Kohori Yoh , Nakada Ichiroh , Yamada Yoshihiro , Amaya Kiichi , Kobayashi Tatsuo , Sakagami Eiji , Kaneko Tetsuyuki , Fujita Hiroshi , Toyoda Haruhisa , Asayama Kunisuke
Published: November 2005

We report measurements of the superconducting and magnetic behaviors of GdBa2Cu3O
x
. Superconductivity sets in at 95 K with large Meissner effect. This compound exhibits Curie-Weiss behavior above T
c with the free-ion effective moments of 7.94µB, and with the Weiss temperature of about - 10±5 K. Moreover, long-range magnetic ordering was observed below 2.2 K by specific-heat measurement without any distinct change of ac susceptibility. This result implies that the superconductivity coexists with the magnetic order below 2.2 K.
Local Interactions and Van Hove Singularities in High-Tc Superconductors
Authors: Shimahara Hiroshi , Takada Satoshi
Published: November 2005

Superconducting transition temperatures (T
c) are studied for a tight binding model with local interactions in two dimensions in connection with van Hove singularities. In the presence of on-site and nearest-neighbor interactions, T
c for the d-pairing, which is most favorable in this case, is calculated, and a useful relation, T
c(µ, δ)\congT
c(µ-δ, 0), is given, where µ and δ are the chemical potential and the next-nearest-neighbor hopping integrals. At the van Hove singularity, the analytic expression for T
c is obtained and shown to agree well with the numerical results. The possibility of the enhancement of T
c due to the van Hove singularity is briefly disscussed for high-T
c superconductors.
Design of Band Potential with a-SixGe1-x:H(F) Alloys
Authors: Shirai Hajime , Oda Shunri , Nakamura Tetsurō , Shimizu Isamu
Published: November 2005

a-Si
x
Ge1-x
:H(F) films incorporating a Ge concentration gradient in the direction of film depth were prepared by hydrogen-radical-enhancd chemical vapor depositin (HRCVD). Their optoelectrical properties were investigated in studies of internal photoemission, photo-induced surface voltage and time-of-flight. These analyses indicate a slope in the conduction band resulting from the compositional profile, which establishes an internal potential gradient and provides for current flow by photogenerated electrons through the films. A transition from non-dispersive to dispersive photocurrents is observed for gradients larger than 5×103 eV/cm.
Crystal Structure of Tetragonal YBa2Cu3-δCoδO7-γ (δ=0, 0.3)
Authors: Kajitani Tsuyoshi , Kusaba Keiji , Kikuchi Masae , Syono Yasuhiko , Hirabayashi Makoto
Published: November 2005

Crystal structures of tetragonal YBa2Cu2.7Co0.3O7-γ and tetragonal YBa2Cu3O7-γ are determined by X-ray and TOF neutron powder diffractometries. Structural parameters are obtained by the Rietveld profile refinement method. In YBa2Cu2.7Co0.3O7-γ', cobalt atoms preferentially occupy one of the copper sites at 1a(0 0 0) rather than the 2g(0 0 z) site with z∼0.36. The lattice constants are a = 3.8644(2)Å and c = 11.7881(9)Å for the quenched YBa2Cu3O6.15 and a = 3.8752(2)Å and c = 11.6851(9)Å for the furnace-cooled YBa2Cu2.7Co0.3O6.81.
Electrical and Luminescent Properties of In-Doped ZnSe Grown by Low-Pressure Vapor-Phase Epitaxy
Authors: Matsumoto Takashi , Iijima Takayuki , Katsumata Yoshihito , Ishida Tetsuro
Published: November 2005

In-doped ZnSe layers have been grown for the first time by low-pressure vapor-phase epitaxy using metallic Zn, Se and In as source materials on GaAs(100) substrates. The carrier concentration increases significantly with increasing In cell temperature, and is controlled in the range of 1016∼1018 cm-3. The near-band-gap emission also increases with In cell temperature. The highest carrier concentration achieved is 1.3×1018 cm-3, and even the most highly doped sample shows a photoluminescence spectrum dominated by the near-band-gap emission.
Sn Incorporation in GaAs by Molecular Beam Epitaxy
Authors: Ito Hiroshi , Ishibashi Tadao
Published: November 2005

The characteristics of heavily Sn-doped GaAs grown by molecular beam epitaxy are investigated. The free carrier concentration saturates at 1×1019 cm-3 for a growth temperature of 600°C and at 2×1019 cm-3 for 400°C. In the saturation region for 600°C, the concentration of incorporated Sn atoms increases with increasing doping concentration. SIMS and electrical characterizations show that the excess Sn atoms are incorporated into GaAs as neutral impurities. The formation of Sn-rich 3D islands does not occur on the GaAs surface at doping concentrations up to around 3×1019 cm-3, which is much higher than the previously reported critical doping concentration of 1×1019 cm-3.
Influence of Bacteria in a Potassium Dihydrogen Phosphate Solution on the Growth Habit of Crystals
Authors: Sasaki Takatomo , Yokotani Atsushi , Fujioka Kana , Nishida Yasunori , Yamanaka Tatuhiko , Yamanaka Chiyoe
Published: November 2005

We found that bacteria present in a potassium dihydrogen phosphate (KDP) solution affect the growth habit of the KDP crystals. Hillocks appeared only on the tapered prismatic surfaces of the crystals grown in solution containing live bacteria. One possible mechanism of this hillock formation is a biochemical reaction between the live bacteria and the KDP crystal.
Interaction between Dislocations and Non-Radiative Recombination Centers in GaAs
Authors: Sekiguchi Takashi , Sumino Koji
Published: November 2005

Interaction of non-radiative recombination centers with dislocations in a LEC-grown GaAs crystal is investigated by observing the change in cathodoluminescence image caused by various heat-treatments. Impurities related to non-radiative recombination centers are gettered by dislocations most effectively at a temperature of around 750°C. The cause of the gettering is concluded to be due to the reaction incorporating the impurities that takes place at the dislocation core.
Characteristics of the Hydrogenated Amorphous Silicon-Crystalline Cadmium Telluride Heterojunction Diode
Authors: Meikle Scott G. , Hatanaka Yoshinori
Published: November 2005

The current-voltage characteristics and visible and X-ray photocurrent characteristics have been investigated for a heterojunction diode constructed of plasma-deposited hydrogenated amorphous silicon (a-Si:H) and single crystal cadmium telluride (c-CdTe). Devices showed low reverse bias saturation current, a photoresponse spectrum ranging from approximately 400-800 nm and a 3 decade increase in reverse bias saturation current when exposed to 40 keV X-rays.
Reflection Spectra of CuInSe2 from 2 to 100 eV
Authors: Takarabe Kenichi , Irie Taizou
Published: November 2005

We report, for the first time, reflectivity up to 100 eV of the chalcopyrite semiconductor CuInSe2 using synchrotron radiation. P-like partial densities of states in the conduction band are identified from the sharp structures at 18 to 22 eV. These structures originate due to the transitions from the In 4d
5/2 core level to the conduction band.
Effect of a Voltage-Gating on Negative Resistance in a Planar p-i-n Diode with Guard Ring
Authors: Choe Il Yong , Akiba Yukio , Kurosu Tateki , Iida Masamori
Published: November 2005

A voltage-gating on the current controlled negative resistance in a planar p-i-n diode with a guard ring is studied using devices with different MOS gate configurations. It is found from this experiment that by applying voltage to a MOS gate, a threshold voltage can be varied from a large value under the open-gate condition to a small value which corresponds to a holding voltage in the on-state. A qualitative explanation is also presented here for the gate control mechanism.
A Novel Electron-Beam Exposure Epitaxy for Growing GaAs Films on Fluoride/Si Structures
Authors: Lee Hee Chul , Ishiwara Hiroshi , Kanemaru Seigo , Furukawa Seijiro
Published: November 2005

A novel heteroepitaxy technique, which we call electron-beam exposure epitaxy (EBE-epitaxy), has been employed in growing GaAs films on CaF2/Si(111) structures. In this method, prior to the growth of GaAs films, the surfaces of CaF2 are exposed to an electron-beam under impingement by arsenic fluxes. It has been found that thin GaAs films with excellent crystallinity and smooth surfaces can be obtained on the CaF2/Si(111) structures. It has also been found that mixing of regular (type A) and rotationally twinned (type B) crystallites does not occur in the films, but that they show preferential and dominant type A orientation which is identical to that of the CaF2.
Thickness Dependence of Superconductivity in As-Sputtered Er-Ba-Cu-O Thin Films
Authors: Hirochi Kumiko , Adachi Hideaki , Setsune Kentaro , Yamazaki Osamu , Wasa Kiyotaka
Published: November 2005

Thin films of Er-Ba-Cu-O system with various thickness have been prepared on R-plane of sapphire by rf-magnetron sputtering. As-sputtered films thicker than 0.15 µm showed superconductivity. As the thickness of the films increased, the transition width decreased and the critical current density increased. As-sputtered film with 1-µm thickness exhibited superconducting transition at onset temperature of 91 K and the zero-ρ state was observed below 80 K.
The Application of Superconducting Ceramics as Substrates for the Electrochemical Deposition of Conducting Polymers and Metals
Authors: Kaneto Keiichi , Yoshino Katsumi
Published: November 2005

Superconducting ceramics of Y1Ba2Cu3O8-δ are studied as electrode substrates for electrochemical deposition of conducting polymers (polythiophene, polypyrrole) and metals (Cu, Ag). The superconductivity of the ceramics is found to be insensitive to the electrochemical processes, and even to exposure to iodine vapor and γ-ray irradiation up to 100 Mrad.
Laser Cooling of a Neon Atomic Beam in Metastable States
Authors: Shimizu Fujio , Shimizu Kazuko , Takuma Hiroshi
Published: November 2005

A neon atomic beam in the 1s5 (J=2) metastable level is cooled by a counterpropagating laser beam using 1s5-2p9 transition. By transferring the 1s5 population to the 1s3 (J=0) metastable level using the optical pumping through 2p2, a cooled 1s3 beam is also generated.
Oxygen-Sensitive Resistivity of La2CuO4 at High Temperatures
Authors: Nozaki Hiroshi , Tanaka Junzo , Shibata Kenji
Published: November 2005

The electrical resistivity of La2CuO4 at high temperatures was studied under various atmospheres. The temperature dependences of the resistivity under air and 1 atm O2 gas showed hystereses in a wide temperature range around 300°C, which was related to the tetragonal-orthorhombic phase transition of the compound. The resistivity rapidly changed depending on oxygen pressure: the resistivities at 690°C were 0.272 Ωcm and 0.70 Ωcm in O2 and N2 gases, respectively. This indicates that the resistivity is very sensitive to oxygen pressure and the compound can be used as an oxygen gas sensor.
Millimeter-Wave Mixing on NbN Superconducting Tunnel Junctions Integrated in a Linear-Array Configuration
Authors: Kita Sadamu , Asahina Katushi , Adachi Susumu , Kobayashi Takeshi
Published: November 2005

NbN(base)/insulator/Pb(counter) tunnel junctions integrated in a linear-array configuration were prepared and used in a millimeter-wave mixing experiment at 35 and 70 GHz. Each junction worked well on the basis of the quantum theory of mixing, though the conversion efficiency was still low due to insufficiently developed mount design and fabrication technology. Owing to the allowance of an optimum local power as large as 10 dB, the linear-array SIS junctionsacted as a sensitive millimeter-wave image sensor: These junctions offered a field intensity distribution inside the waveguide at 35 GHz.
A New Grating Fabrication Method for Phase-Shifted DFB LDs
Authors: Numai Takahiro , Yamaguchi Masayuki , Mito Ikuo , Kobayashi Kohroh
Published: November 2005

A new grating fabrication method for phase-shifted DFB LDs has been developed. This method, which uses a phase-shift layer, exhibits very good reproducibility. The fabrication yield was almost 100%. A cw single-longitudinal-mode(SLM) operation as high as 42 mW was achieved for a 1.55 µm DFB-DC-PBH LD with a λ/8-shifted grating fabricated by this method.
DC-SQUID with High-Critical-Temperature Oxide-Superconductor Film
Authors: Nakane Hideaki , Tarutani Yoshinobu , Nishino Toshikazu , Yamada Hiroji , Kawabe Ushio
Published: November 2005

Voltage vs magnetic-flux characteristics of a DC-SQUID using YBa2Cu3O7-δ film have been studied. YBa2Cu3O7-δ film SQUID was fabricated by lithographical patterning. The DC-SQUID operated up to 72 K.
Amplification of Photoconductive Gain with Space Charge Doping nini Multilayered Structure
Authors: Shirai Hajime , Nakamura Tetsurō , Shimizu Isamu
Published: November 2005

Optoelectrical properties of a-Si:H(F) multilayers consisting of alternating intrinsic and phosphorus doped layers (nini structure) have been investigated as a function of sublayer thickness by steady state and transient photocurrent measurements. The modulation of the band potential by space charge doping leads to high photoconductivity of the order 10-3 S/cm under an illumination of 1014 photons/cm2s, while maintaining a dark conductivity as low as that of 10-10 S/cm. A high photoconductive gain above 10 is obtained for the reverse-biased Schottky diode by controlling the ratio of its thickness and doping level.
Temperature Dependence of Resistivity and its Anisotropy of Ba-Y-Cu-O Single Crystals
Authors: Murata Keizo , Hayashi Kunihiko , Honda Yoshiaki , Tokumoto Madoka , Ihara Hideo , Hirabayashi Masayuki , Terada Norio , Kimura Yoichi
Published: November 2005

The temperature dependence of resistance of single crystals of Ba2YCu3O7-y
was examined. The resistance perpendicular to the plane exhibited a semiconductor-like temperature dependence, while the resistance parallel to the a-b plane was metallic. Thus, the anisotropy of conductivity increased at low temperature.
Electron-Beam-Induced Current Observation of Misfit Dislocations at Si1-XGeX/Si Interfaces
Authors: Kohama Yoshitaka , Watanabe Yoshio , Fukuda Yukio
Published: November 2005

The electron-beam-induced current (EBIC) method has been applied to observing the misfit dislocations at Si1-X
Ge
X
/Si interfaces in order to determine directly the dependence of critical layer thickness h
c on mole fraction X. The EBIC images show square-grid patterns that agree with a chemical etched pattern. The typical dislocation image width obtained by EBIC is about 0.5 µm, which approximately agrees with the resolution introduced from the lateral-dose function. It has been found that the dependence of h
c on X judged from whether or not the misfit dislocations generate cannot be explained by the theory presented by People and Bean.8)
Dislocation Reduction in GaAs on Si by Thermal Cycles and InGaAs/GaAs Strained-Layer Superlattices
Authors: Okamoto Hiroshi , Watanabe Yoshio , Kadota Yoshiaki , Ohmachi Yoshiro
Published: November 2005

The etch-pit density of epitaxial GaAs layers grown on Si was significantly reduced by using the technique of growth interrupt and thermal cycles (in situ TC) followed by growth of In0.1Ga0.9As/GaAs strained-layer superlattices (SLS's). The etch-pit density of 1.4×106 cm-2 (density of small pits by molten KOH etching) was achieved in 3.5 µm-thick GaAs epilayers. It was also found that the effect of SLS's on dislocation reduction was more enhanced by combining with the in situ TC process than the effect when SLS's were used by themselves.
Fabrication of Superconducting YBa2Cu3O7-δ Films by a Tape Casting Method
Authors: Ishii Mamoru , Maeda Takao , Matsuda Motohide , Takata Masasuke , Yamashita Tsutomu
Published: November 2005

Films of the superconductor YBa2Cu3O7-δ(YBCO) were prepared by a tape casting method. The resistivity of the films was measured by the four-probe method and the superconduction was observed at T
c=96 K(onset) and 91 K(end).
Grain Boundary Josephson Junctions Using Y-Ba-Cu-O Films Operative at 77 K
Authors: Tanabe Hisao , Kita Sadamu , Yoshizako Yuji , Tonouchi Masayoshi , Kobayashi Takeshi
Published: November 2005

Grain boundary Josephson junctions were fabricated from superconducting oxide Y-Ba-Cu-O films. The junctions were made by a chemical wet etching technique with phosphoric acid (H3PO4) solution. Typical dimensions of the junctions were a width of 4 µm and a length of 20 µm. The junctions showed the so-called bridge-type Josephson effect. Shapiro steps were observed in the I-V curves at a temperature as high as 77 K.
Electron Paramagnetic Resonance Studies of Defects in Silicon-Implanted SiO2
Authors: Fujita Tetsuo , Fukui Minoru , Itoh Noriaki
Published: November 2005

Electron paramagnetic resonance measurements in silicon-implanted amorphous SiO2 at room temperature have been carried out. In samples implanted at a dose of 1×1017 Si+ cm-2, only the defects in SiO2 were detected, while in samples implanted at a dose of 5×1017 Si+ cm-2, both the defects in SiO2 and in amorphous Si were observed, indicating that amorphous Si is formed in the latter samples.
A Method for Producing High-Tc Y-Ba-Cu-O Superconducting Filaments by Die-Free Spinning
Authors: Gotō Tomoko , Horiba Iwao
Published: November 2005

The preparation of high-T
c Y-Ba-Cu-O superconducting filaments was studied by die-free spinning. An aqueous solution of Y, Ba and Cu nitrate containing PVA and dispersant was prepared, then the reacted mixture of the Y-Ba-Cu-O powder was dispersed in the solution to make slurry-type spin dope. The spin mixture was gently withdrawn and coiled on a winding drum. The long filament obtained was about 150 µm in diameter and consisted of up to 66.7 wt% nitrate and 26.7 wt% oxide content. The filament was heated to remove volatile components and to generate the layered perovskite phase. The heated filament exhibited superconductivity at 82 K.
A New Preparation Method of Ultrafine Particles of Metallic Sulfides
Authors: Kaito Chihiro , Saito Yoshio , Fujita Kazuo
Published: November 2005

Ultrafine particles of metallic sulfides have been produced by the reaction of metal and sulfur vapor. The sulfur vapor was prepared by evaporating sulfur powder from a quartz boat using the atmospheric temperature of either the heated metal or boat. Electron microscopic observation of the particles of Mo3S4 and PbS has shown them to be typical examples of the produced sulfides.
Preparation of Ba2YCu3O7-y with Tc below 65 K
Authors: Ono Akira , Sueno Shigeho , Kobayashi Michiko , Ishizawa Yoshio
Published: November 2005

The compound Ba2YCu3O7-y
(7-y<6.7) was prepared using a successive heat treatment of a sample by (1) quenching from high temperature, (2) sealing in a gold capsule, (3) heating and cooling in a furnace and (4) annealing at 420°C followed by (5) final quenching. Linear depression of the superconducting transition temperature occurred with increasing c dimensions of the final products. The orthorhombic phase with 7-y<6.5 could not be prepared, and the tetragonal phase with the c cell dimension of 11.743-11.757 Å was also unstable below 570°C, and unknown green phases were produced instead of Ba2YCu3O7-y
.
Theoretical Prediction of the Orthorhombic (II) Phase in the YBa2Cu3O7-δ System
Authors: Kubo Yoshimi , Igarashi Hitoshi
Published: November 2005

The existence of the orthorhombic(II) phase in the YBa2Cu3O7-δ system is derived by a model calculation of the oxygen order-disorder transformation on the Cu(1) plane. The repulsion interaction energy between the second-nearest-neighboring oxygen atoms contributes to the occurrence of the orthorhombic(I)-orthorhombic(II) transformation while the first-nearest interaction gives rise to the tetragonal-orthorhombic(I) transformation. The structure of the orthorhombic(II) phase is considered to be an alternately-ordered state of the oxygen atoms within the a-axis site.
Growth of YBa2Cu3O7-δ Single Crystals
Authors: Katayama-Yoshida Hiroshi , Okabe Yutaka , Takahashi Takashi , Sasaki Taizo , Hirooka Tsuguyoshi , Suzuki Takashi , Ciszek Ted , Deb Satyen K.
Published: November 2005

Large single crystals of high-temperature superconductor YBa2Cu3O7-δ (T
c ∼ 90 K) have been successfully grown in the cavity of bulk materials with a CuO flux. Crystals with a typical size of 2×2×0.3 mm3 were obtained. As-grown single crystals do not show superconductivity at liquid nitrogen temperature. However, after annealing in O2 flow for three days, they become superconductive at T
c ∼ 90 K.
Observation of the Opening/Closing of a Diffuse Discharge in a Mixture of C2HF3/He by KrF Laser Irradiation
Authors: Sasagawa Teruo , Kawahara Akihiro , Obara Minoru
Published: November 2005

We have successfully demonstrated the opening of diffuse discharge in a mixture of C2HF3/He (1.5 Torr of He with 0.5% C2HF3) by KrF laser irradiation. After the laser irradiation, a current peak appeared and then the discharge current decreased with a time constant of 200 µs, resulting in the interruption of the current. We have also observed the discharge initiation by KrF laser irradiation of the same fluence.
A Superstructure Model to Interpret the Diffuse Electron Scattering Observed in Ba2YCu3Oy
Authors: Matsui Yoshio
Published: November 2005

A new superstructure model is proposed, which explains the diffuse electron scattering observed in some specimens of high-T
c superconductor Ba2YCu3O
y
(y is nearly 6.6). A unit cell of the superlattice is A
s=2a, B
s=b and C
s=c, where a, b and c are the lattice parameters of the original orthorhombic lattice of Ba2YCu3O
y
(a<b). The superstructure is derived by removing oxygen atoms on every other (-O-Cu-O-Cu-O-) one-dimensional chain in the basal plane of the original orthorhombic structure. The resulting structure is a unit-cell-level mixture of the orthorhombic and tetragonal structures of Ba2YCu3O
y
.
Optical Reflectivity of Single Crystals of YBa2Cu3O7-δ and ErBa2Cu3O7-δ
Authors: Wang Xiao-lei , Nanba Takao , Ikezawa Mikihiko , Hayashi Shigeyuki , Komatsu Hiroshi
Published: November 2005

Optical reflectivity in the a
b-plane of single crystals of YBa2Cu3O7-δ and ErBa2Cu3O7-δ has been observed at room temperature in the energy region from 0.5 to 5.6 eV. The reflectivity is isotropic in the a
b-plane around the Drude edge at 1.5 eV. In the low-energy region below the edge, it is explained well by the Drude formula for the free carriers with an extremely short relaxation time of about 4×10-16 s.
Ab initio MO Studies on the Correlation and Spin Correlation Effects for Copper-Oxygen and Copper-Halogen Bonds in High-Tc Copper Oxide Superconductors
Authors: Yamaguchi Kizashi , Takahara Yoichi , Fueno Takayuki , Nasu Keiichiro
Published: November 2005

The correlation and spin correlation effects for Cu+2XCu+2 (X=F-1, Cl-1 and O-2) were investigated by the ab initio molecular orbital (MO) method. It is found that these effects are particularly strong for Cu+2F-1Cu+2, while they are rather weak for Cu+2O-2Cu+2. Implications of the ab initio MO results are discussed in relation to the high-T
c superconductivity for La-Ba-Cu-O and R-Ba-Cu-O (R=Y, etc.). The working hypotheses derived are applied to the molecular design of organic superconductors.
Optical Fiber Fabrication by the Out-Diffusion Method
Authors: Kitagawa Takeshi , Shibata Shuichi , Horiguchi Masaharu
Published: November 2005

Single-mode optical fibers with triangular index profile are successfully fabricated by a new fabrication technique, the “out-diffusion method”. Evaporation and diffusion of fluorine by heating and subsequent collapsing of the fluorine-doped silica glass tubes result in formation of the core in the center of the collapsed preforms. Optical fibers with refractive index difference of 0.67% are obtained with an optical loss of 0.40 dB/km at 1.57 µm wavelength.
The Evaluation of Multiplexability of a Supertwisted Nematic Liquid Crystal Display Device in Terms of Crosstalk Ratio
Authors: Yoshida Ken-ichi , Kubota Hiroshi , Gomes Cleber Magalhaes , Shimomura Teruo , Kobayashi Shunsuke
Published: November 2005

The multiplexability of a supertwisted nematic (STN)-LCD was evaluated in terms of crosstalk ratio. The effects of driving waveform, contrast polarity, and reflective versus transmissive modes of these LCDs were well expressed by the crosstalk ratio. These results were compared with those for a conventional TN-LCD. The STN-LCD (operated at the duty ratio of 1/200) gave a crosstalk ratio of about 20% while the TN type gave 60%. This shows a distinct and quantitative superiority of the STN type in multiplexability compared with the TN-LCD.
Lattice-Mismatch Enhanced Diffusion at a ZnSe/GaAs Interface - Increase of Thermal Stability in a Lattice-Matching System
Authors: Ohmi Koutoku , Suemune Ikuo , Kanda Takashi , Kan Yasuo , Yamanishi Masamichi
Published: November 2005

ZnSe/GaAs interface diffusion, especially at an elevated temperature, was investigated. For ZnSe films of which stoichiometry was not completely maintained at the interface, the enhancement of Zn diffusion into GaAs was observed with an increase of film thickness. With preheating of GaAs substrates prior to growth, ZnSe films are stably deposited on GaAs. However, for thick ZnSe films of 7200 Å, the original n-ZnSe/n-GaAs interface turned out to be converted to p-type at the interface after thermal annealing at 650°C for three hours. These interface diffusions which depend on the film thickness are estimated to be related with the misfit-induced lattice relaxation caused above a critical thickness. This hypothesis was confirmed by the extreme thermal stability found in the lattice-matched ZnS0.06Se0.94/GaAs interface.
Compositional Disordering of Focused-Si-Implanted GaAs/AlGaAs Superlattices by Rapid Thermal Annealing
Authors: Uematsu Masashi , Yanagawa Fumihiko
Published: November 2005

Compositional disordering of focused-Si-implanted GaAs/Al0.5Ga0.5As superlattices, followed by rapid thermal annealing (RTA), was investigated by means of sputtering Auger electron spectroscopy (AES) and Raman spectroscopy. Complete disordering was found to take place in the superlattices focused-Si-implanted with a dose of 5×1015 cm-2 and annealed at 1000°C for 4 to 30 seconds, resulting in an Al0.25Ga0.75As alloy. The Raman spectra showed that this alloy had a higher quality as the implanted samples were annealed for longer periods of time.
MOCVD Growth of InGaP on GaP Substrates and Its Application to Visible LEDs
Authors: Iwamoto Takashi , Mori Kazuo , Kukimoto Hiroshi
Published: November 2005

InGaP has been grown on GaP substrates by low pressure metalorganic chemical vapor deposition (MOCVD) using triethylindium, triethylgallium and phosphine. A buffer layer with step-graded alloy composition is inserted between the GaP substrate and the InGaP layer with a constant composition to reduce the influence of lattice mismatch. A trial fabrication of In0.34Ga0.66P light-emitting diodes(LEDs) has indicated that the diode efficiency is about one order of magnitude lower than commercially available GaAsP yellow LEDs. Further improvement in the efficiency is also discussed.
Alignment Signal from a Mark Deformed by Molecular Beam Epitaxial Overgrowth for Focused Ion Beam Implantation
Authors: Morita Tetsuo , Takamori Akira , Arimoto Hiroshi , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

The geometry of an alignment mark is deformed by molecular beam epitaxial (MBE) overgrowth on it. The secondary electron intensity profile was calculated by using Monte Carlo simulation when a focused ion beam (FIB) scanned across the deformed mark. The calculated result agreed with the measured one and we confirmed that this calculation method can be used even for complicated marks. The peak positions are very distinct after MBE growth and the measured alignment error after growth of a 1 µm layer was less than 0.3 µm. A 4 µm thick multi-layered/doped structure was fabricated by an iterative process in which MBE growth was followed by FIB implantation 4 times with an alignment error of less than 0.5 µm.
C-Si-O(B) Thin Film-A Possible X-Ray Mask Substrate Candidate
Authors: Montasser Kadry , Yamada Hitomi , Morita Shinzo , Hattori Shuzo
Published: November 2005

The formation of a C-Si-O(B) compound by plasma CVD at an rf frequency of 13.56 MHz is described. B2H6 (5.25 (vol. %) in nitrogen) and CH4 were the reactant gases. Argon and nitrogen were used alternatively as the carrier gases. The substrate temperature was in the range 150-300°C. The films were inadvertently formed. However, although they had been inadvertently obtained they could be reproduced. The depth profiles of those films are given to explain the deposition mechanism. The exposure of those films to the UVSOR is also illustrated.
Zn and Si Ion Emission from Au-Zn-Si LM Ion Source
Authors: Arimoto Hiroshi , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

An Au-Zn-Si LM (liquid metal) ion source for Zn ion beam, which can promote a compositional disordering of GaAs-AlAs superlattices as well as act as a p-type dopant in III-V compound semiconductors, has been demonstrated. The lifetime of this source was restricted to about 50 hours due to a selective evaporation of Zn atoms from the liquid alloy surface. However, the vapor pressure of Zn in the alloy at 410°C was estimated to be 2.3×10-3 Pa (1.7×10-5 Torr). This value is 4 orders smaller than that of elemental Zn.
Magnetic Properties of Compositionally Modulated Fe/SiO2 Films
Authors: Togami Yuji , Morishita Tadataka , Tsushima Kuniro
Published: November 2005

Compositionally modulated Fe/SiO2 films prepared by sputtering method show a well-defined multilayer structure. Magnetization of Fe/SiO2 films has been studied by a vibrating sample magnetometer. Magnetization of Fe layers decreases gradually with the decrease of Fe thickness (d
Fe) in the range of d
Fe smaller than 100 Å. However, even when the Fe layer is thinner than monolayer thickness, it shows ferromagnetic behavior at 77 K. Moreover, an Fe layer in a (Fe 1.5 Å/SiO2 28.9 Å) film has an easy axis of magnetization normal to the film plane.
Relationship between Bridge Energy and Metallic Phase Arc Duration in Electric Contacts
Authors: Sato Kiminori , Sato Tomohiko , Sone Hideaki , Takagi Tasuku
Published: November 2005

In order to find the relationship between arc duration, contact resistance and bridge energy in electric contacts, a new system for measuring bridge waveforms has been developed. The bridge energy was controlled by heating the contact electrode. The experimental results showed that the arc duration of opening contact is closely related to the bridge energy supplied to its bridge state. This fact suggests that the amount of metallic vapor (initial condition) plays an important role in maintaining the metallic phase arc discharge.
Determination of Al Composition and DLTS Measurements of AlxGa1-xSb on GaSb Substrate
Authors: Takeda Yoshikazu , Gong Xiao Cheng , Zhu Yu , Sasaki Akio
Published: November 2005

DLTS (Deep Level Transient Spectroscopy) measurements have been carried out to investigate the electron-trap levels in Te-doped Al
x
Ga1-x
Sb over a composition range from 0 to 0.4. Deep electron-traps were not detected in Te-doped n-type GaSb and AlGaSb with Al composition lower than 0.2, but a high concentration of deep electron-traps was detected at higher Al composition. Al composition in this heteroepitaxial system was accurately determined by double crystal X-ray diffraction and EPMA.
Magnetic Fe-C Films Prepared by Getter Sputtering on High Temperature Substrates
Authors: Watanabe Katsuro , Munakata Makoto , Goto Kimiyoshi
Published: November 2005

Magnetic Fe-C films were deposited by getter sputtering using alloy targets with nominal compositions of Fe3C, Fe2.5C and Fe2C. Substrates used were quartz and their temperature was changed from 150° to 600°C. Magnetic properties of the films have been studied with analyses of film compositions and structures. With the increase of substrate temperature T
sub, the coercive force increases and then decreases through maximum values of 250∼310 Oe at T
sub=350°∼400°C. It has been shown that the high coercive force results mainly from Fe3C crystallites less than 1000 Å in size.
Colorimetrie Evaluation of an ECD for the Reflection- and Transmission-Types
Authors: Shimomura Teruo , Furuta Takashi , Maki Toshiharu
Published: November 2005

An electrochromic display device with a liquid electrolyte of 1 mol/l LiClO4 in propylene carbonate is evaluated for its colorimetric characteristics. The colorimetric characteristics are shown by the lightness index, chromatic index, color difference vs the injected charge amount and by the lightness index vs the chromaticness index. The characteristic of the lightness index vs the chromaticness indexis independent of the thickness sof tungsten oxide films and its characteristic-curve can be showed by a cubic equation for the reflection- and transmission-types.
High-Tc Superconductivity and Diamagnetism of Y-Ba-Cu Oxides
Authors: Takagi Hidenori , Uchida Shin-ichi , Kishio Kohji , Kitazawa Koichi , Fueki Kazuo , Tanaka Shoji
Published: November 2005

A high T
c superconductivity was confirmed in an oxide mixed phase system of Y-Ba-Cu-0. The resistivity drop sets in at 95 K, went through the mid-point at 90 K and finalized at 75 K. Furthermore, the diamagnetism as large as 5% of the complete Meissner effect was observed below 90 K, indicating the superconductivity to be of the bulk nature rather than filamentary or interfacial one.
High Tc Superconductivity of (La1-xSrx)2CuO4 –Effect of Substitution of Foreign Ions for Cu and La on Superconductivity
Authors: Hasegawa Tetsuya , Kishio Kohji , Aoki Makoto , Ooba Naoki , Kitazawa Koichi , Fueki Kazuo , Uchida Shin-ichi , Tanaka Shoji
Published: November 2005

In order to elucidate the electronic structure of (La1-x
Sr
x
)2CuO4, the sites of Cu and La were substituted with various 3d and 4f transition elements, respectively. The substitution on the Cu sites at 5 atomic percent level substantially destroyed the superconductivity whereas that on the La sites raised much less adverse effect. The results were discussed in terms of the two-dimensional conduction model based on the planar -Cu-O-Cu-O- linkage.
Superconductivity at 95 K in the New Yb-Ba-Cu Oxide System
Authors: Kitazawa Koichi , Kishio Kohji , Takagi Hidenori , Hasegawa Tetsuya , Kanbe Shinsaku , Uchida Shin-ichi , Tanaka Shoji , Fueki Kazuo
Published: November 2005

A reproducible superconducting transition between 83 and 95 K has been observed both resistively and magnetically in the new Yb-Ba-Cu oxide system at ambient pressure. The superconducting phase has been attributed to (Yb1-x
Ba
x
)3 Cu2O7-δ which has a quite similar structure to that of Sr3Ti2O7 but with a large oxygen deficiency.
Specific Heat and Superconductivity in (La1-xCax)2CuO4
Authors: Kitazawa Koichi , Sakai Masayuki , Uchida Shin-ichi , Takagi Hidenori , Kishio Kohji , Kanbe Shinsaku , Tanaka Shoji , Fueki Kazuo
Published: November 2005

Specific heat of (La0.925Ca0.075)2CuO4 was measured by the thermal relaxation method both under zero magnetic field and under H=5.7T. The discontinuity in the specific heat C was clearly observed at the superconducting transition temperature T
c (∼18 K). The electronic specific heat coefficient γ value, estimated from the discontinuity ΔC, was about 20 mJ/(mol·K2).
High Tc Magnetic Superconductor: Ho-Ba-Cu Oxide
Authors: Hikami Shinobu , Kagoshima Seiichi , Komiyama Susumu , Hirai Takashi , Minami Hidetoshi , Masumi Taizo
Published: November 2005

A new material, holmium-barium-copper oxide, becomes a superconductor. Its onset temperature of the superconductivity is 93 K and the resistance vanishes below 76 K. By microwave SQUID method, a diamagnetism is found at 4.2 K.
Electronic Structure of La2CuO4 by APW Method
Authors: Takegahara Katsuhiko , Harima Hisatomo , Yanase Akira
Published: November 2005

The self-consistent APW band calculation for the body centered tetragonal structure La2CuO4, which is a proper reference material for the study of the origin of high-temperature superconductivity in (La1-x
M
x
)2CuO4 compounds, has been done using the local density approximation. The bonding-antibonding splitting of the Cu 3d(x
2-y
2) and O 2p states results in a pair of subbands of about 0.58 Ry width. The half-filled antibonding band has the two dimensional property and nearly square Fermi surface.
Effect of Hydrostatic Pressure on the Superconducting Transition Temperature of (La1-xBax)2CuO4-y with x=0.075
Authors: Kurisu Makio , Kadomatsu Hideoki , Fujiwara Hiroshi , Maeno Yoshiteru , Fujita Toshizo
Published: November 2005

The pressure dependence of superconducting transition temperature T
c of (La1-x
Ba
x
)2CuO4-y
with x=0.075 was determined under hydrostatic pressure up to 20 kbar. It is found that T
c linearly increases and the width of transition is broadened with pressure. The pressure enhancement of T
c is interpreted as being a support for the suggestion that T
c is correlated with the copper-oxygen distance.
Electron Diffraction and Microscopy of the Structure of La-Ba(Sr)-Cu Oxides at Room Temperature
Authors: Hirotsu Yoshihiko , Nagakura Sigemaro , Murata Yuzo , Nishihara Takaharu , Takata Masasuke , Yamashita Tsutomu
Published: November 2005

Structural study of the La-Ba(Sr)-Cu oxides was made by means of electron diffraction and microscopy at room temperature. In the orthorhombic La1.9Ba0.1CuO4 weak extra reflections are found and the space group was determined as P
c
c
m. On the other hand, no extra reflections are found for the tetragonal La1.8Ba0.2CuO4 with onset T
c=28 K and La1.8Sr0.2CuO4 with onset T
c=36 K. High resolution reveals the metal atom arrangement in these compounds.