bluuebunny/crossref_metadata_2025 huggingface dataset:
An Improved Tight Binding Band Structure Calculation of (GaAs)n/(AIAs)n (n=1∼4) Superlattices
Authors: Nara Shigetoshi
Published: November 2005

The electronic band structure of (GaAs)
n
/(AIAs)
n
(n=1∼4) superlattices is investigated by means of an improved tight binding method, in which the overlap integrals up to the second nearest neighbor atoms, including new parameters, are explicitly taken into account in order to improve the fitting of the lowest conduction band in the bulk materials to the results of the pseudopotential method. The two cases of band offset values based on Dingle's rule and Kroemer's rule are employed and the resulting band structure is compared. The oscillator strength between the valence band top and the three of the lower conduction band minima at Γ-point is calculated and compared with a photoluminescence experiment.
Compensation Effect in Electrical Conduction Process: Effect of Substituent Group
Authors: Mitra Bani , Misra T. N.
Published: November 2005

The semiconductive properties of Vitamin A acid (Retinoic Acid), a long chain conjugated polyene, were studied as a function of the adsorption of different vapours. A compensation effect was observed in the electrical conduction process; unlike that in Vitamin A alcohol and Vitamin A acetate3) the compensation temperature was observed on the lower side of the experimental temperature (T
0≈285 K). It is concluded that the terminal \diagdown
\diagupC=0 group conjugated to the polyene chain plays an important role in the manifestation of the compensation effect. Various conduction parameters have been evaluated.
Magnetic Properties of Magnetite Ultrafine Particles Prepared by W/O Microemulsion Method
Authors: Bandow Shunji , Kimura Keisaku , Kon-no Kijiro , Kitahara Ayao
Published: November 2005

The magnetizations of a magnetite colloid prepared by a Water/Oil microemulsion method were measured. Magnetization curves are not represented by a simple Langevin function, but are given by a complex formula incorporating the surface condition of ultrafine particles. The temperature dependence of the spontaneous magnetization is different from the bulk and is explained by considering the existence of surface magnetism. The size distribution of colloidal particles is a log-normal type with a mean diameter of d̄=3.6 nm and with a standard deviation of σ=1.28 (from an electron micrograph).
An Electron Undulating Ring Dedicated to VLSI Lithography
Authors: Tomimasu Takio
Published: November 2005

The unique capability of synchrotron radiation (SR) from the electron undulating ring has been shown to be advantageous for expanding the exposed area of SR in VLSI lithography. Vertical and horizontal undulating motions of stored beams have been demonstrated around the horizontal design orbit using two perturbator magnets. The maximum vertical displacement of a 500-MeV beam is ±10 mm and the maximum vertical tilt angle of the undulating beam near the nodes is ±2.5 mrad for a perturbator field of 130 gauss with an azimuthal length of 28 cm. The vertical undulating beam near the node can expand the exposed area of SR by a factor of more than five. The perturbator field dependence of the tilt angle and the relation between the nodes observed in the undulating motion and the betatron numbers are explained using an empirical expression.
A Study of Optimum Operation by Voltage Mode Control for Solar Photovoltaic Systems
Authors: Murozono Mikio , Kita Yutaro , Takakura Hideyuki , Kubota Masao , Hamakawa Yoshihiro
Published: November 2005

The optimum operating conditions of solar cell modules for photovoltaic systems have been studied by acquiring complete field operation data for two kinds of modules during a period of more than 1 year. The annual output energy from a CZ Si solar cell module under maximum output conditions is 1284 Wh/Wp/year and that of an EFG ribbon Si module is 1117 Wh/Wp/year in Osaka, Japan. The difference between the annual output under fixed voltage operation and that under maximum output operation conditions is 31.35 Wh/Wp/year for the CZ module and 41.44 Wh/Wp/year for the EFG module, respectively. If the operating voltage is adjusted every month to the optimum value, these differences can be greatly reduced to 15.42 Wh/Wp/year (CZ) and 20.29 Wh/Wp/year (EFG). It has been shown that an optimum operation of a solar array can be realized by adjusting parametric changes in the photovoltaic performances using the cell temperature and insolation intensity.
Observation of Fine Compositional Fluctuation in GaAs/AIxGa1-xAs Superstructure Using Composition Analysis by Thickness-Fringe (CAT) Method
Authors: Kakibayashi Hiroshi , Nagata Fumio , Ono Yuichi
Published: November 2005

The fine compositional fluctuation in a GaAs/Al
x
Ga1-x
As superstructure grown by metal-organic chemical vapor deposition (MOCVD) was evaluated by using the composition analysis by thickness-fringe (CAT) method. A sinusoidally oscillating Al composition in the growth direction was observed to have a period of 1∼4 nm and in the range x=0.15 to 0.5. The CAT method was successfully applied to measure such fine compositional fluctuations with a high spacial resolution.
Electrochromic Properties of V2O5 Thin Films Colloid-Chemically Deposited onto ITO Glasses
Authors: Yoshino Takako , Baba Nobuyoshi , Kouda Yasuo
Published: November 2005

The dynamic properties of a V2O5 ECD cell prepared by the sol-get method are mentioned. The V2O5 thin film was electrochemically deposited onto ITO glass from a poly-vanadic acid sol. The response time of the ECD cell was 2–20 seconds, depending upon the cell voltage. The repeating time was more than 8×104 times. It is possible to fabricate large-area ECD cells by this method.
Low Temperature Growth of SiO2 Thin Film by Double-Excitation Photo-CVD
Authors: Inoue Kohji , Michimori Masanori , Okuyama Masanori , Hamakawa Yoshihiro
Published: November 2005

A new technique for the low-temperature growth of SiO2 films has been developed by double-excitation photo-CVD. SiO2 films can be grown at 30∼240°C from a mixture of Si2H6 and O2 by photo-CVD using a D2 lamp as a VUV light source, or by double-excitation using an additional Xe lamp or a low-pressure Hg lamp as a UV light source. The growth rate is 90 Å/min in a photo-CVD at 30°C, while deposition does not occur in thermal CVD at 30°C. Concentrations of Si–OH and Si–H bonds can be considerably reduced by the use of photo-excitation. Particularly, double-excitation reduces the oxide-charge density to a large extent and also brings the dielectric constants close to those of thermally-grown SiO2. The minimum charge density is 5×1010 cm-2 in a film deposited at 240°C. The interface state density of a Si MOS diode is also reduced by double-excitation using a Hg lamp in an O2-excess atmosphere and annealing at 280°C. Its minimum density is 8×1010 cm-2eV-1.
Preparation of SiO2Film by Photo-Induced Chemical Vapor Deposition Using a Deuterium Lamp and Its Annealing Effect
Authors: Toyoda Yoshihiko , Inoue Kohji , Okuyama Masanori , Hamakawa Yoshihiro
Published: November 2005

Silicon dioxide thin films have been prepared at low temperatures from SiH4and O2by direct photo-induced CVD using a deuterium lamp. The growth rate is 75 Å/min at 84°C while no growth occurs below 180°C without deuterium lamp irradiation. UV and VUV light irradiation and an increase of the substrate temperature have effects of increasing the refractive index, and decreasing H incorporation and the amount of the oxide charge. The photo-CVD films deposited above 180°C show refractive indices of 1.45–1.46. Annealing in an O2environment decreases the infrared absorptions due to Si–H stretching, Si–OH deformation and Si2O3bondings as well as the oxide charge. The activation energies of the Si–H, the Si–OH deformation, the Si2O3and the oxide charge obtained from the annealing characteristics are 0.18–0.19, 0.12, 0.19 and 0.12–0.13 eV, respectively. The reduction of Si–OH deformation absorption is considered to be closely related to the reduction of oxide charge.
Metal/Silicon Reactions Studied by High Energy Jon Scattering
Authors: Ito Toshimichi , Gibson W. M.
Published: November 2005

The initial stages of the metal/silicon reactions have been investigated for Au, Ag, Pd/Si(111) and Au, Ag/Si(001) systems with film thicknesses less than ∼15 ML (1 ML≈7×1014 atoms/cm2) using a MeV ion scattering/channeling technique. In addition to single metal depositions, sequential depositions of two different metals were performed. In the former case, obvious differences in the reactivities at the interfaces were observed for the Au/Si, Pd/Si (reactive) and Ag/Si systems (little reactive). Sequential depositions of Au and Ag brought forth interesting results. Predeposited Au of \lesssim2 ML enhanced displacements of Si during subsequent Ag depositions, irrespective of the substrate orientations. The interfacial reactions of the noble metal(s)/Si and the Pd/Si systems are discussed in relation to the damage cross section of Si crystal atoms near the interfaces.
Growth and Characterization of Compositionally Graded (Ca, Sr)F2 Layers on Si(111) Substrates
Authors: Kanemaru Seigo , Ishiwara Hiroshi , Asano Tanemasa , Furukawa Seijiro
Published: November 2005

Epitaxial insulator films composed of compositionally fixed (Ca, Sr)F2/compositionally graded (Ca, Sr)F2/CaF2 multilayers have been grown on Si(111) substrates by the coevaporation of CaF2 and SrF2 from two separate crucibles The dependence of the channeling minimum yields on the energy of incident ions in Rutherford backscattering spectroscopy revealed that defects in the top fluoride layers were mainly dislocations. The dislocation density could be reduced by decreasing the compositional gradient of the underlying graded layers and decreasing the growth temperature. As a result of the reduced dislocation density, the generation of cracks in fluoride films could be suppressed.
Thermal Oxidation of Sputtered TaN Films and Properties of the Oxidized Films
Authors: Yamagishi Haruo , Miyauchi Masayoshi
Published: November 2005

The thermal oxidations of a sputtered TaN film and the properties of an oxidized TaN (TaNO) film were investigated. By oxidation at around 600°C in dry oxygen, conductive TaN converts into an amorphous insulator which develops, after subsequent annealing at about 800°C, to a mixed compound consisting of main hcp Ta2O5 and amorphous nitride phases. The oxidation is controlled by a diffusion process. Capacitance measurements yield a relative dielectric constant of about 20. The dielectric breakdown strength is more than 2×106 V/cm. The TaNO film was found to be very suitable as a capacitor-forming material for microwave GaAs ICs in conformity with a self-align Au/TaN/WN/GaAs gate FET process.
Thermal Degradation of a-Si:H Solar Cells by Dopant Diffusion
Authors: Takada Jun , Yamaguchi Minori , Fukada Noboru , Nishimura Kunio , Tawada Yoshihisa
Published: November 2005

In glass/TCO/p(a-SiC:H)-i-n/Cr type hydrogenated amorphous silicon solar cells fabricated by a rf glow-discharge decomposition method, it was observed that the photocurrent in the short-wave length region mainly decreased after a thermal treatment of the sample. In terms of a simple model in which the dopant diffusion makes a dead layer near the p/i interface, the phenomenon of the photocurrent decrease is discussed. The dopant diffusion coefficients and the lifetimes of the solar cells were estimated.
Photoluminescence of InGaP/GaAs (111) LPE Layers with Elastic Strain due to Lattice Mismatch
Authors: Kato Takamasa , Matsumoto Takashi , Ishida Tetsuro
Published: November 2005

The influence of the elastic strain due to a lattice mismatch on the photoluminescence spectrum was studied. Energy shifts in the band-to-band emission were measured as a function of the misfit strain for InGaP layers grown on GaAs (111)A and (111)B substrates. The shift in bandgap energy was proportional to the lattice mismatch in the range (Δa/a
0)f\lesssim0.16%. When (Δa/a
0)f>0.16%, the shifts in the bandgap energy were nearly constant. These results show that the misfit strain induced by the lattice mismatch was accommodated elastically for (Δa/a
0)f\lesssim0.16%. For larger values of (Δa/a
0)f, misfit-dislocations were introduced and the grown layers were deformed plastically in part. Sub-band emissions observed below the band-to-band emission became minimal when the epitaxial layer was lattice-matched to a GaAs substrate at the growth temperature.
Accommodation of Large Lattice Mismatch of GaP on GaAs(100) and GaAs on GaP(100) Layers Grown by MBE
Authors: Nomura Takashi , Maeda Yuuji , Miyao Masahiro , Hagino Minoru , Ishikawa Kenji
Published: November 2005

To investigate the accommodation of a large lattice mismatch, the misfit strain of a GaP layer grown on a GaAs(100) substrate and a GaAs layer grown on a GaP(100) substrate were studied by X-ray diffraction and Raman spectroscopy as a function of the layer thickness. Epilayers were grown by MBE. The misfit strain began to relaxed at a thickness of 50 nm for GaP and 80 nm for GaAs. The magnitude of the saturated strain was 0.48% for GaP and 0.13% for GaAs. These magnitudes are insufficient to make a coherent interface. The tendency of our results are different from Matthews' prediction. His theory deals with layer-by-layer growth. Whereas the RHEED pattern showed an island formation during the initial stage of growth, subsequent islands coalesced to form a flat surface. Thus, the difference between the prediction and the experimental results was probably due to the difference in the growing mechanism.
Band-Edge Shift and X1–X3Absorption Depending on Donor Concentration in GaP
Authors: Endo Tamio , Sawa Kazuhiro , Hirosaki Yuushi , Taniguchi Shizuo , Sugiyama Koichi
Published: November 2005

The fundamental absorption-edge and the X1–X3absorption band (α1-band) were investigated at 300 K forn-GaP with various doping levels. The correction of the α1-band with the donor-electron-related absorptions can not be neglected for high donor concentrationsND. For increasingND, the optical gap shrinks asEg10=2.233-1.39×10-8N1/3D, the X1–X3threshold energy δ increases and decreases (increases) the effective mass ratiom2*/m1*(the effective massm1*), wherem1*is for the X1-band andm2*for the X3-band. Some discussions are made regarding the apparent increase inm1*. The increase in δ is attributed to a downward shift of the conduction band-edge (X1). Such shift of ∼5 meV evaluated experimentally is close to the shift of 8.8 meV calculated by Mahan's model with increasingNDfrom 2×1017to 2×1018cm-3.
Radial Profiles of Electron Density and Current Components at Cathode Surface in LaB6 Hollow Cathode Arc
Authors: Suzuki Setsuo , Asano Toshiaki , Morimiya Osami
Published: November 2005

Experimental studies on a hydrogen-fed LaB6 hollow cathode arc have been pursued. The plasma parameter in the cathode has been measured by a Langmuir probe. The radial variation in the electron density inside the cathode was calculated using the continuity and momentum equations, showing good agreement with the experimental results. The electron density at the cathode surface was estimated to be 15%–20% of that at the cathode axis. It was also found from the current balance that the arc current components at the cathode surface consist of a thermionic current which takes into account the Schottky effect, the ion current and the secondary electron current induced by ion bombardment. The ion current and the cathode surface is larger than the electron current emitted from the cathode.
Spurious Frequency Spectra Caused by the Scattered Lights from Transparent Channel Wall in the Laser Doppler Velocimetry
Authors: Okada Eiji , Minamitani Haruyuki
Published: November 2005

Spurious frequency spectra, SFS, in laser Doppler velocimetry, caused by a superposition of the scattered light from a stationary transparent wall of a thin flow channel with the incident light are discussed and systematically analyzed. The observed SFS as well as the amplitude of SFS changed with the position and aperture size of the receiving optics. They were entirely different from the so-called frequency broadening and the characteristics indicated that the scattered light served as reference beams on the heterodyne detection of the Doppler signals. A theoretical analysis of the SFS, undertaken by using a simple model, is compared with experimental results; both were in good agreement. A rejection method of SFS is also discussed.
Alignment Accuracy of Focused Ion Beam Implantation
Authors: Morita Tetsuo , Arimoto Hiroshi , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

The theoretical alignment limit for focused ion beam (FIB) implantation was deduced from the calculated resolution for the detection of an alignment mark. The alignment resolution varies with the signal to noise ratio and there is an optimum current which gives the best resolution. The alignment resolution εσ is approximately 0.006 µm for a 160 keV Si++ beam from our FIB implanter. The measured alignment error is approximately 0.06 µm and the main reason of this discrepancy is vibration. The ultimate limit on the alignment error can be reached through improvements in the implanter system.
Interferometric Nanometer Alignment for a Wafer Stepper by Two Wave-Front Reconstruction onto Deformed Wafer Gratings
Authors: Nomura Noboru , Yamashita Kazuhiro , Yamada Yuichiro , Suzuki Masaki , Takemoto Toyoki
Published: November 2005

A discussion is presented on a reduction projection wafer stepper with an interferometric nanometer alignment detector by two wave-front reconstruction. The optics of the detector to form an interferometer comprises two coherent beams and a grating on a wafer. The alignment detector detects the relative position of the reticle grating to the wafer grating. It has been verified that the response sensitivity to the step movements of the wafer was 5 nanometers. The response signals received from various deformed alignment gratings indicated an ideal cosine wave form. The resultant overlay to the irregular surface gratings on an Al deposited wafer was improved to 0.1 µm/3 sigma.
Power Stabilization of Hollow Cathode He–Cd+White Light Laser
Authors: Fuke Akira , Masuda Katsuhiko , Tokita Yasuhiro
Published: November 2005

The laser power stabilization of the hollow cathode He–Cd+white light laser was studied. The power stabilization must be projected for three color lights; red, green, and blue, because the white light laser is composed of the three color lights. The laser output variation is mostly caused by Cd vapor pressure and input power. Then to reduce the variation, the authors proposed three techniques: the inclusive anode power control technique, the individual anode power control technique, and the light feedback control technique and compared them to each other. The feedback technique has realized the best output stability: the short-time output power variations (fluctuations) in red, green, and blue obtained by the experiment were 0.32%, 0.18%, and 0.32%, respectively.
Correction to “Thermodynamic Theory of III–V Semiconductor Ternary Solid Solutions”
Authors: Onda Tomohiro , Ito Ryoichi
Published: November 2005

Modified is our theory presented in the article, Jpn. J. Appl. Phys. 25 (1986) 82, entitled “Thermodynamic Theory of III–V Semiconductor Ternary Solid Solutions”. Adopting a more accurate expression for the entropy of mixing, we present an improved description for short-range clustering/ordering and a revised expression for the free energy.
Superconducting Transition Temperatures of V3Si Films Formed by Reactive Diffusion
Authors: Goto Toshinari , Tsurumi Tatsuo , Usami Kouichi
Published: November 2005

V films deposited on Si films, SiO films and fused quartz plates were annealed at various temperatures between 500 and 950°C; then, their superconducting transition temperatures and residual resistances were measured. A couple of V and Si films annealed at 850°C was found to form a superconducting V3Si layer with the highest T
c onset (17 K), the smallest ΔT
c (0.4 K) and the largest residual resistance ratio (6.64) of all the couples studied.
Experimental Study of a Plasma Generated by a θ-Discharge
Authors: Suzuki Hiroshi , Nobata Kanehiro
Published: November 2005

The characteristics of a pre-ionization plasma generated by a θ-discharge which included no compression process were experimentally examined by means of interferometry, a magnetic loop and a streak camera. In contrast to conventional pre-ionization techniques, the θ-discharge can produce a quiescent, magnetized plasma with no density fluctuation; the degree of ionization of the resulting plasma is about 50%.
Electron Temperature Measurement by Electron Cyclotron Emission from Tandem Mirror GAMMA 10
Authors: Koseki Tadashi , Mase Atsushi , Miyoshi Syoichi
Published: November 2005

Measurements of electron cyclotron emission were carried out in order to estimate the electron temperature in the central and plug cells of a tandem mirror, GAMMA 10. The emission from hot electrons is substracted by considering a relativistic shift of resonance layers. The plug electron temperature is much larger than the central one, which represents a reduction of thermal conduction across the thermal barriers.
Electron Model Experiment of Slow Positron Accumulator
Authors: Kinugawa Tohru , Arikawa Tatsuo
Published: November 2005

A preliminary model experiment of a slow positron accumulator essentially based on the principle of the spiral orbit spectrometer (SOS) was carried out using an electron beam of with energies between 200 and 50 eV. Electrons were captured well into the equilibrium orbit of the accumulator for about 30 µs at 200 eV. The lifetime, revealed to be limited simply by collisions with residual gasses and a much longer storage time, would be expected under a better vacuum condition.
Electron Spin Resonance and Photoluminescence in a-Si1-xCx:H Deposited at Low Substrate Temperature
Authors: Yoshimoto Masahiro , Fuyuki Takashi , Matsunami Hiroyuki
Published: November 2005

Electron spin resonance and photoluminescence were measured for a-Si1-x
C
x
:H films deposited at low substrate termperatures by a glow discharge method. In the range of the carbon content above 0.55, where the films show intense photoluminescence, the spin density in the film deposited at room temperature was less than 5×10-2 of that in the film deposited at 260°C. The lower spin density comes from the incorporation of a large number of H atoms in the film deposited at room temperature, which results in the intense photoluminescence.
Electrical Properties of La-Sr-Cu-O/Al Contact
Authors: Takeuchi Kiyoshi , Okabe Yoichi , Kawasaki Masashi , Koinuma Hideomi
Published: November 2005

Current-voltage characteristics of La-Sr-Cu-O(LSCO)/Al contacts have been measured. The results imply that the dominant conduction mechanism is Schottky emission, and that an insulating layer exists between the LSCO and the aluminum. The thickness and the relative dielectric constant of the layer have been estimated to be 25 nm and 7.5 respectively from its capacitance and the slope of the current-voltage plot.
Detection of Adsorbed Hydrogen on W(001) by Using 1H(15N, αγ)12C Reaction
Authors: Iwata Yasushi , Fujimoto Fuminori , Vilalta Eugeni , Ootuka Akio , Komaki Ken-ichiro , Kobayashi Koichi , Yamashita Hiroshi , Murata Yoshitada
Published: November 2005

Hydrogen coverage on W(001) was measured by using the resonant nuclear reaction 1H(15N, αγ)12C. The detection limit of the hydrogen coverage was 1/50 of the full monolayer, i.e. 4×1013 H atoms/cm2. The coverage dependence of the sticking probability of hydrogen was estimated by considering the ion-stimulated desorption of hydrogen. The zero-point energy of the vibration of adsorbed hydrogen atoms in the direction perpedicular to the surface was obtained by the Doppler broadening of the resonance width as 64±16 meV.
Structure of Tetragonal YBa2Cu3O5.8
Authors: Katano Susumu , Funahashi Satoru , Hatano Takeshi , Matsushita Akiyuki , Nakamura Keikichi , Matsumoto Takehiko , Ogawa Keiichi
Published: November 2005

A single-phase YBa2Cu3O5.8 with a tetragonal symmetry shows a semiconductor-like resistivity down to 4.2 K. The crystal structure of this compound has been determined by the Rietveld profile analysis of neutron powder diffraction data measured at 10 K. The space group P4/mmm is confirmed, and lattice constants are a=3.8607(3) Å and c=11.774(1) Å. The oxygen site 2 g(0 0 0.1553) is fully occupied, but the occupation of the 4i site (1/2 0 0.3786) is 0.91 and that of the 2f site (1/2 0 0) is only 0.07.
The Dependence of the Superconducting Transition upon the Quench Temperature of YBa2Cu3Oy
Authors: Sawada Hideaki , Iwazumi Toshiaki , Saito Yosuke , Abe Yoshihito , Ikeda Hiroshi , Yoshizaki Ryozo
Published: November 2005

The superconducting transition properties have been evaluated for YBa2Cu3O
y
compound samples prepared after processing from vairous quench temperatures following a sintering stage at 880°C. Two sets of temperatures depicting the onset of the superconducting transition have been observed. One set is found to cover 79-94 K for samples with orthorhombic symmetry, and the onset temperature increases as the quench temperature is lowered. The other set is found to cover the range 52-58 K for samples with tetragonal symmetry.
Above Band-Gap Excitation Process of the 0.6 eV Luminescence Band in GaAs
Authors: Tajima Michio , Iino Takayuki , Ishida Koichi
Published: November 2005

The transition mechanism of the 0.6 eV luminescence band, observed commonly in undoped semi-insulating GaAs crystals under the above band-gap excitation (AGE), has been investigated by photoluminescence excitation spectroscopy. We show that the 0.6 eV AGE band consists of the 0.63 and 0.68 eV bands with the same recombination processes as in the case of the below band-gap excitation. The peak of the 0.6 eV AGE band shifts with the excitation photon energy as a result of the discontinuity in the excitation spectrum of the 0.68 eV band. This discontinuity is explained by the presence of the excitation process via the excited state of the EL2 level resonant with the conduction band.
Fabrication and Properties of Nb Variable-Thickness Bridge Array
Authors: Goto Toshinari , Ohtsuka Ryouhei , Kobayashi Tadayuki
Published: November 2005

Variable-thickness bridge series array is fabricated in a Nb thin film by means of electron beam lithographic technique and slant evaporation technique. The critical current spread and array resistance are ±15% and 9 Ω, respectively. Near the critical temperature of the weak region we obtain a result which implies that all twelve bridges are locked to the first and the second Josephson voltage steps.
The Low Temperature Reaction of Radiation Defects in GaAs Introduced by γ-Ray at 33 K
Authors: Tomozane Mamoru , Nannichi Yasuo , Kamada Hidehiko , Ando Koshi
Published: November 2005

For the first time, the low temperature (< 83 K) reaction of defects in GaAs introduced by irradiation at low temperature (33 K) was observed by improved thermally stimulated current spectroscopy. The irradiation was done by Co60 γ-ray. A newly found level (0.13 eV) was observed after the irradiation. It disappeared by thermal annealing below 83 K. The annealing rate at 83 K was estimated as larger than 10-2 s-1. After the 0.13 eV level disappeared, another level (0.18 eV), which is usually observed as E2 in GaAs irradiated by electron beam, appeared and grew by subsequent annealing. The 0.18 eV level, E2, is likely due to a complex resulting from 0.13 eV level.
Effect of Selective Doping on the Emission Characteristics of a Heavily Si-Doped GaAs/AlGaAs Quantum Well
Authors: Kamata Norihiko , Tsuchiya Hiroshi , Kobayashi Kikuo , Suzuki Takeo
Published: November 2005

Spontaneous emission characteristics in a heavily doped active layer have successfully been improved by using a selective doping structure. It is observed that at a sheet carrier density of 1.6×1013 cm-2 a selectively Si-doped GaAs/AlGaAs multiple quantum-well has a higher radiative recombination rate than a uniformly doped structure with a recombination lifetime of 0.6 ns. Spatial separation of impurities from recombining majority and minority carriers has eliminated the formation of band tail and the impurity-related nonradiative centers from the well layer.
High-Efficiency, High-Luminance Gas-Discharge Mode for Color TV Display
Authors: Okamoto Yukio , Fukushima Masakazu
Published: November 2005

High-efficiency and high-luminance are obtained at the transition from Townsend discharge to normal glow discharge, i.e., at subnormal glow discharge mode. Also found is that efficiency increases with shorter pulse duration t
A and is inversely proportional to the mean discharge current. On the contrary, luminance increases by shorterning t
A and has a maximum. Experiments are carried out with short pulsed voltage ranging from 20 to 1000 ns.
Carrier Concentration Dependent Absorption Spectra of Modulation Doped n-AlGaAs/GaAs Quantum Wells and Performance Analysis of Optical Modulators and Switches Using Carrier Induced Bleaching (CIB) and Refractive Index Change (CIRIC)
Authors: Sakaki Hiroyuki , Yoshimura Hisao , Matsusue Toshio
Published: November 2005

Optical absorption spectra of modulation doped quantum wells were studied systematically at 77 K and 300 K as functions of the two dimensional electron concentration N
s. It has been found that the absorption at the wavelength of exciton peak is bleached strongly from 2.1×104 cm-1 to 800 cm-1 at 77 K as N
s is raised from zero to 1×1012/cm2; this is due to the combined effect of exciton quenching and Burstein Moss shift, which override the band gap reduction caused mainly by the many body effect. Performance analysis of quantum well optical modulators and switches using this carrier induced bleaching (CIB) and refractive index change (CIRIC) is presented to show the picosecond switching capability with low drive voltages.
Synchrotron Radiation-Assisted Etching of Silicon Surface
Authors: Hayasaka Nobuo , Hiraya Atsunari , Shobatake Kosuke
Published: November 2005

The photo-assisted etching of heavily phosphorous-doped polycrystalline silicon by chlorine was studied using synchrotron radiation as an extreme ultraviolet (EUV) light source. The quantum yield for the removal of the Si atoms at a chlorine pressure of 0.3 Torr was found to be about 0.5% photon-1 using the Ti-filtered light, which is mostly in the EUV region, 1-20 nm. Formation of electronically excited Cl+ ions upon EUV irradiation was confirmed by emission spectroscopy. Negative bias applied to the Si crystal was found to increase the etch rate.
A Storage Type Electrochromic Display Utilizing Poly-Co-QTPP Films
Authors: Yamana Masao , Kashiwazaki Naoya , Yamamoto Motokazu , Nakano Tomoyasu
Published: November 2005

A storage type electrochromic display is fabricated by a Poly-Co-quarternized 3,4-tetrapyridinoporphyrazine (Poly-Co-QTPP) film which is deposited on an In-Sn oxide (ITO) glass by electrochemical reduction. The reduced form of the Poly-Co-QTPP film is stored more than one month without electrical power and resists oxidation in the presence of oxygen.
Disordering of Surface Regions in Si-Implanted Superlattices of GaAs/AlGaAs
Authors: Matsui Kazunori , Kobayashi Junji , Fukunaga Toshiaki , Ishida Koichi , Nakashima Hisao
Published: November 2005

Disordering in Si implanted GaAs/AlGaAs superlattices is studied by secondary ion mass spectrometry. Samples implanted with 160 keV Si+ at doses 3×1013 to 3×1015 cm-2 are examined before and after 1 h annealing with an SiO2 cap. Dual implantation of 160 keV and 40 keV Si+ is also examined. The results indicate that the disordering of the surface region can be controlled by the concentration balance of implantation-induced defects and Si.
Crystal Structure of Ba1.5La1.5Cu3O7-x
Authors: Izumi Fujio , Asano Hajime , Ishigaki Tōru , Takayama-Muromachi Eiji , Matsui Yoshio , Uchida Yoshishige
Published: November 2005

The crystal structure of Ba1.5La1.5Cu3O7-x
(tetragonal, Z=1) was determined by the combined use of electron diffraction and X-ray powder diffraction. The length of the c axis is nearly three times as large as that of the a axis : a=3.9108 Å and c=11.707 Å. Rietveld analysis of the X-ray diffraction data showed that this compound has a layered structure very similar to that of the tetragonal form of Ba2YCu3O7-x
. Oxygen atoms on a z=1/2 plane are lackinag completely, and the occupation factor of oxygen at (0, 1/2, 0) is 0.6.
A 140 ps Optical Pulse Generation by Field-Induced Gain Switching in a Photo-Excited Quantum Well Laser
Authors: Takeoka Tadashi , Yamanishi Masamichi , Kan Yasuo , Suemune Ikuo
Published: November 2005

Modulation of light output power by field-induced gain switching in a photo-excited AlGaAs graded-index-separate-confinement heterostructure quantum well laser is, for the first time, demonstrated at low temperature (∼40 K). The modulation is caused by changes in spatial separation, e.g., overlapping of electrons and holes in the GaAs well and graded barrier layers with electric field perpendicular to the hetero-junction plane. An optical pulse as narrow as 140psec full width at half-maximum is generated.
Ba-Y-Cu-O Superconducting Tape Prepared by Surface Diffusion Process
Authors: Kumakura Hiroaki , Yoshida Yuji , Togano Kazumasa
Published: November 2005

Ba-Y-Cu-O superconducting tapes were fabricated by the reaction between Cu substrate and mixture of BaCO3 and Y2O3 powders. Two layers of different compounds were formed on the Cu substrate after the reaction. The outer layer consisted of Ba2Y1Cu3O9-y
superconducting compound and the inner layer was identified as Cu2O. Superconducting transition temperatures of 93 K (onset) and 40 K (offset) for the tapes were obtained.
Selective Epitaxial Growth of InAs on GaAs by Molecular Beam Epitaxy
Authors: Okamoto Akihiko , Ohata Keiichi
Published: November 2005

InAs was selectively grown on GaAs by conventional molecular beam epitaxy(MBE). No InAs growth was found on SiO2, except small InAs particles, when the substrate temperature was between 550 and 600°C and arsenic pressure was 1×10-5 Torr. The higher the substrate temperature, the better the selectivity. At 650°C, no growth was found on GaAs nor on SiO2. Selective epitaxial growth by MBE has been realized under proper growth conditions, and will be useful for device applications.
A Pseudopotential Approach to Mixing Enthalpies of Disordered (GaAs)1-x(Ge2)x
Authors: Ito Tomonori
Published: November 2005

This paper outlines the investigation of mixing enthalpies and total crystal energies of (GaAs)1-x
(Ge2)
x
with disordered diamond structure using a pseudopotential perturbation approach. The calculated results show that disordered (GaAs)1-x
(Ge2)
x
is metastable and has a miscible region over the entire concentration range at very low temperatures in contrast with those of ordered (GaAs)1-x
(Ge2)
x
.
Electron Diffraction and Microscope Study of Radiation Damage in Ba2YCu3Oy
Authors: Matsui Yoshio , Takayama-Muromachi Eiji , Kato Katsuo
Published: November 2005

Electron induced radiation damage in a high T
c superconductor Ba2YCu3O
y
, where y varies from 5.8 to 6.5, was examined by electron diffraction and high resolution transmission electron microscopy (HRTEM). Disordering of Ba and Y layers in the A-sites of the tri-perovskite structure is induced by an intense electron irradiation. Radiation induced product probably has a cubic structure with a=0.41 nm, which is slightly larger than a, b and c/3 values, 0.38-0.39 nm, of an original Ba2YCu3O
y
structure.
Synthesis of Y-Ba-Cu-O Thin Films on Sapphire Substrates by RF Magnetron Sputtering
Authors: Michikami Osamu , Asano Hidefumi , Katoh Yujiro , Kubo Shugo , Tanabe Keiichi
Published: November 2005

Y-Ba-Cu-O thin films have been prepared on sapphire substrates by RF magnetron sputtering from sintered targets. The substrate temperature dependence of Ba and Cu concentrations against Y of as-sputtered films has been clarified. Film composition deviated from target composition. Cu concentration decreased significantly with increasing T
s, while Ba concentration was independent of the substrate temperature. Using the CuO-compensated Y1Ba6Cu10O
x
target, assputtered high-T
c films (T
c onset=87 K, T
c endpoint=40 K) have been successfully obtained as a T
s of about 580°C.
Difference in Electroluminescent ZnS:Tb, F Thin Films Prepared by Electron-Beam Evaporation and RF Magnetron Sputtering
Authors: Mita Juro , Koizumi Masumi , Kanno Hiromasa , Hayashi Tadashi , Sekido Yoshihiro , Abiko Ichimatsu , Nihei Kohji
Published: November 2005

To clarify the difference in ZnS:Tb,F films fabricated by electron-beam evaporation (EB) and by rf magnetron sputtering (SP), the doping condition of Tb and F ions was investigated by electron probe micro analysis and secondary ion mass spectroscopy. The F/Tb atomic ratio of 3 and EL spectra for EB films are found to be hardly affected by annealing. As the model for luminescent centers, it is proposed that the Tb and F ions are substituted for Zn and three S ion sites, respectively, with two Zn vacancies for satisfying charge compensation. For the SP films, interstitial F ions are released from ZnS film and Tb-F complex centers are formed by annealing.
Observation of the Josephson Effect in Y-Ba-Cu-O Compound
Authors: Higashino Yasushi , Takahashi Takahiro , Kawai Takashi , Naito Seiichi
Published: November 2005

This letter describes a weak-link Josephson junction with critical current of 10 mA and normal resistance of 0.02 Ω. The junction was fabricated from a rod of Y1Ba2Cu3O
x
compound.
The rod was bonded to a ceramic substrate, for mechanical stability, and a diamond-edged cutting wheel was used to cut a narrow slot in the rod, leaving a small land where the two “islands” of rod are connected. The junction can with-stand thermal cycling between room temperature and 77 K. The AC Josephson effect was observed at 77 K, the temperature of liquid nitrogen, when X-band microwave radiation was applied.
A Crystallographic Study on Ba2YCu3O7-y
Authors: Ono Akira
Published: November 2005

Unit cell dimensions and oxygen contents of Ba2YCu3O7-y
were determined at room temperature for two kinds of specimens with different oxygen contents as functions of annealing temperatures. Unit cell dimensions of ordered orthorhombic phases increase linearly with decreasing oxygen content regardless of the phase transition temperature which is about 570°C. This is evidence for existence of intrinsic phase transition caused by ordering of oxygen atoms. It has been found that oxygen content 7-y equals -5.454c+70.512 where c is c cell dimensions in angstroms.
Crystal Structure of the High Tc Superconductor TmBa2Cu3O7-δ
Authors: Ishigaki Tōru , Asano Hajime , Takita Kôki
Published: November 2005

The crystal structure of the high T
c superconductor TmBa2Cu3O7-δ has been determined by Rietveld analysis of X-ray powder diffraction data. The crystal system is orthorhombic (space group Pmmm) with lattice parameters a=3.8746(2) Å, b=3.8087(1) Å and c=11.6655(6) Å. The structure is isomorphic with YBa2Cu3O7-δ. The Tm and Ba atoms have an ordered arrangement, O in the z=1/2 plane is completely missing and O on the basal Cu plane is deficient. The compound shows superconductivity at 90.5 K (midpoint) with the transition width of 3.0 K.
Lasing Spectrum of P Co-Doped Nd3+ Silica Fibers
Authors: Kimura Yasuo , Nakazawa Masataka
Published: November 2005

Co-doping effects for the fluorescence and lasing spectrum of Nd3+-doped silica fibers have been studied. Alternating the concentration ratio between Nd3+ and P atoms, the peak lasing wavelength can be changed from 1.064 µm to 1.092 µm. A fiber laser configuration which can increase the laser tuning range up to 93 nm at 4F3/2-4I11/2 transition is proposed.
Chemical Vapor Deposition of CuGaS2 Using Chloride Sources
Authors: Matsumoto Takashi , Nakanishi Hiroshi , Ishida Tetsuro
Published: November 2005

The chemical vapor deposition of CuGaS2 using CuCl, GaCl3 and S sources and N2 carrier gas has been studied for the first time. The synthesized deposits are characterized by an X-ray diffraction method and confirmed to be CuGaS2 with chalcopyrite structure. CuGaS2 layers are grown on GaAs(111) substrates at ∼700°C and show green luminescence due to donor-acceptor pair recombinations at 2.299 eV at 4.2 K.
Compositional Variation of High Tc in YbxEr1-xBa2Cu3O6+y System
Authors: Ishida Takekazu
Published: November 2005

The high-T
c superconductivity of Yb
x
Er1-x
Ba2Cu3O6+y
has been investigated in terms of the X-ray powder diffraction pattern as well as of the resistive superconducting transition. X-ray structure shows that our samples have almost single-phase orthorhombic. T
c varies linearly with respect to x, suggesting that Yb3+ or Er3+ is not irrelevant to the mechanism to determine T
c.
Structures and Upper Critical Fields of High Tc Superconductors (RE)Ba2Cu3Ox
Authors: Tamegai Tsuyoshi , Watanabe Akiko , Oguro Isamu , Iye Yasuhiro
Published: November 2005

A systematic study of structure and superconductivity of (RE)Ba2Cu3O
x
(RE: rare earch) is carried out. All superconducting (RE)Ba2Cu3O
x
have oxygen deficient perovskite structure. As the ion radius of the RE ion increases, lattice parameters increase and the orthorhombic distortion becomes smaller. Superconducting transition temperature is lower for (RE)Ba2Cu3O
x
with smaller RE ion radius. Upper critical fields (H
c2) are measured resistively up to 90 kOe. All superconducting (RE)Ba2Cu3O
x
have similar values of dH
c2/dT|
T
c
to that of YBa2Cu3O
x
. The estimated H
c2 at absolute zero ranges from 1250 kOe to 1850 kOe.
A Resonant-Tunneling Bipolar Transistor (RBT) –A New Functional Device with High Current Gain
Authors: Futatsugi Toshiro , Yamaguchi Yasuhiro , Imamura Kenichi , Muto Shunichi , Yokoyama Naoki , Shibatomi Akihiro
Published: November 2005

A resonant-tunneling bipolar transistor (RBT) has been proposed and demonstrated. This is a AlGaAs/GaAs hetero-junction bipolar transistor using a AlAs/GaAs/ AlAs quantum well resonator as a minority carrier injector. The RBT exhibits a collector-current peak with respect to the base-emitter voltage, and therefore a negative transconductance, due to resonant-tunneling of electrons. The common-emitter current gain reaches 20 at 77 K. We also observed a base-current peak due to resonant-tunneling of holes.
A Pseudomorphic In0.53Ga0.47As/AlAs Resonant Tunneling Barrier with a Peak-to-Valley Current Ratio of 14 at Room Temperature
Authors: Inata Tsuguo , Muto Shunichi , Nakata Yoshiaki , Sasa Shigehiko , Fujii Toshio , Hiyamizu Satoshi
Published: November 2005

We have studied the effect of barrier height on the negative differential resistance characteristics of In0.53Ga0.47As-based resonant tunneling barriers (RTBs), including In0.53Ga0.47As/(In0.52Al0.48As)
x
(In0.53Ga0.47As)1-x
RTBs, lattice-matched to an InP substrate, and In0.53Ga0.47As/AlAs pseudomorphic RTBs also grown on InP substrates. A peak-to-valley current ratio of 14 (300 K) and 35 (77 K) with a high peak-current density of 2.3×104A/cm2 was achieved for a resonant tunneling barrier structure of In0.53Ga0.47As (15 atomic layers)/AlAs (9 atomic layers).
Impurity Injection using Multiple-Shell Pellet
Authors: Itoh Sanae-Inoue , Itoh Kimitaka
Published: November 2005

A model of a three-layered multiple-shell pellet is studied in order to apply it to an impurity injection experiment. The mass dependence of the ablation is examined by employing the neutral-cloud shielding model. The localization width of the impurity is estimated.
Concentration Effects of Gadolinium to the Properties of Superconductor-YBa2Cu3Oy
Authors: Tominaga Akira , Nakamura Fumihiko , Narahara Yoshimasa
Published: November 2005

Yttrium of the YBa2Cu3O
y
system is replaced by Gadolinium. Orthorhombic crystal structure and ratios of lattice constains are preserved, while lattice constants increase as the concentration of Gd becomes larger. After satisfactory annealing in oxygen atmosphere the superconcucting transition temperatures are independent of Gd concentration. Superconducting phase below T
c shows large diamagnetic susceptibility and below 60 K superconducting fraction of the sample becomes 90% of nominal volume.
Frequency Dependence of AC Josephson Effect in Point-Contact (Y, Er) BaCuO/Nb
Authors: Kita Sadamu , Tanabe Hisao , Takahashi Tetsuro , Tonouchi Masayoshi , Fujiwara Yasufumi , Kobayashi Takeshi
Published: November 2005

Microwave and millimeterwave dependences of ac Josephson effect were investigated in YBaCuO ceramic superconductors. We observed very clear constant-voltage steps (Shapiro steps) on the current-voltage curve of YBaCuO/Nb junctions at signals of 14.1,25.5 and 35.0 GHz. The observed step voltages were frequency dependent in accordance with the (h/2e)f rule. This strongly suggests that pair-electrons serve as the superconducting particle even in ceramic materials.
In addition, the ac Josephson effect was also observed in point-contact ErBaCuO ceramics containing a magnetic element Er.
Optical Properties of Solution of Polythiophene Derivatives as Functions of Alkyl Chain Length, Concentration and Temperature
Authors: Yoshino Katsumi , Nakajima Shigeaki , Gu Hal Bon , Sugimoto Ryu-ichi
Published: November 2005

Optical transmission through the cell of solutions of polythiophene derivatives such as poly(3-octylthiophene), poly(3-dodecylthiophene) and poly(3-dococylthiophene) has been found to change drastically with temperature and concentration. This transmission change is also dependent on the alkyl chain length. The critical temperature T
c of the transition between two transmission states (opaque and transparent) increases with increase in both concentration and chain legth.
This phenomenon has been conjectured to originate in the change of light scattering due to some conformational transition of polymers in the solvent. An application of this phenomenon has also been proposed.
Pressure Dependence of High-Tc Superconducting Oxides
Authors: Kaneko Takejiro , Yoshida Hajime , Abe Shunya , Morita Hiroaki , Noto Kohshichi , Fujimori Hiroyasu
Published: November 2005

Pressure dependence of the superconducting transition temperature T
c and the lattice parameter for high-T
c oxides is discussed on the basis of Cyrot's model in which T
c is proportional to t
2/U (t is the transfer integral and U the intraatomic Coulomb repulsion). The relation between dT
c/dP and K
v
T
c (K
v is the volume compressibility) is examined in connection with the emperical relation found for magnetic compounds with an antiferromagnetic superexchange interaction in which T
N is proportional to t
2/U.
Development of a Microcomputer-Controlled Instrument for Preparing Complex(Hetero-) LB Films Fully Automatically
Authors: Kato Teiji
Published: November 2005

A high-performance instrument for preparing hetero-LB films fully automatically was developed. Two microcomputers linked together through an RS-232C communication line control surface pressures of monolayers digitally using four control parameters and complicated movement of a solid substrate. Double gates which permit the passage of solid substrates but which prohibit monolayers are used to deposit hetero-LB films. Model experiments show that the gates work well and the resultant hetero-LB films have very high regularity.
Change of Magnetization Characteristics on Bias Modulated Co-CoO Layered Film Using Reactive Sputtering
Authors: Tamari Kousaku , Kusuda Tetsuzo , Yamashita Akira , Honda Shigeo
Published: November 2005

The magnetic interaction between Co and CoO is thought to influence the magnetic properties of reactive sputtered Co-O perpendicular magnetization films. Co-CoO multi-layered films were prepared using a conventional rf sputtering method by modulating the substrate bias, and the effect of the interaction between Co and CoO on magnetic properties of films was investigated. For the Co-CoO multi-layered films prepared by bias modulation, the perpendicular magnetic anisotropy was induced by shortening the modulation period. For layered films with a short period, the saturation magnetization decreases and the coerciving increases with the decreasing ratio of Co layer thickness to CoO layer thickness. Bias modulated Co-CoO films with layered structure show the perpendicular magnetization when the modulation period is less than 50 Å.