bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Oxygen Doping on Bulk Properties of CuInSe2 Crystals
Authors: Matsushita Hiroaki , Saburo Endo Saburo Endo , Taizo Irie Taizo Irie
Published: February 2005

The structural and electrical properties of CuInSe2 bulk crystals annealed in air were investigated. The electrical resistivity decreased and the carrier concentration increased with an increase of the annealing temperature for the p-type samples. A shallow acceptor level of about 50 meV was found and attributed to the doped oxygen. The n-type samples was converted to p-type by annealing at 300°C in air.
Critical Current Density and Flux Creep in Melt-Processed Bi-Pb-Sr-Ca-Cu-O Superconductors
Authors: Umemura Toshio , Nozaki Ayumi , Egawa Kunihiko , Fusaoki Uchikawa Fusaoki Uchikawa , Ken Sato Ken Sato
Published: February 2005

We investigated the critical current density and the flux creep in melt-processed Bi-Pb-Sr-Ca-Cu-O for the purpose of studying the existence of strong flux pinning forces due to normal conducting precipitates. We fabricated samples with a similar microstructure to melt-processed Y-Ba-Cu-O and Tl-Sr-Ca-Cu-O having a strong pinning force. When the matrix was (Bi, Pb)2Sr2Ca1Cu2O
y
(2212) phase, the irreversibility field B
irr was expressed as B
irr\propt(1-T/T
c)3/2, which suggested that the expected flux pinning was due to normal conducting precipitates. A part of the matrix was transformed to (2223) phase by the postannealing of the sample; however, the superconducting properties were inferior to those observed in (2223) polycrystals.
Design and Analysis of the X-Waveguide Optical Switch in a MESFET Geometry
Authors: Gautam Dinesh Kumar , Koji Ishida Koji Ishida , Kunio Tada Kunio Tada
Published: February 2005

Theoretical analysis of the change in refractive index, in the channel of a GaAs MESFET (metal oxide semiconductor field effect transistor) structure, has been presented for the first time. The analysis shows great potential applications, to use the MESFET geometries, in the design of optical modulators, and switches for monolithic integration. A X-waveguide-type optical switch has been incorporated into the MESFET geometry, and its switching characteristics have been studied by using the beam propagation method. No switching region has been deliberately built into the waveguide. Instead, the gate and drain voltages of the MESFET automatically form and control the switching region. A light wave propagated through a waveguide is reflected by the depletion edge due to the large change of refractive index. An extinction ratio better than 8.75 dB has been obtained at the gate voltage of 7 V.
New Recordable Compact Disc with Inorganic Material, AgOx
Authors: Tominaga Junji , Haratani Susumu , Kenji Uchiyama Kenji Uchiyama , Suguru Takayama Suguru Takayama
Published: February 2005

A new recordable compact disc (CD-R) was formed with sputtered silver oxide, instead of organic dye. The optical and electrical properties were mostly equal to those of a CD-R with organic dye. The optical absorption of sputtered AgO
x
is uniform over a wide range of light wavelength, and more than 70% of the reflectance can be obtained at any laser wavelength applied by selecting the thickness of the dielectric film. It was found that the recording principle mostly depends on the explosion pressure of released oxygen from AgO
x
due to the laser power of recording.
Valence State of Europium in CaS Prepared Using Alkaline Polysulfide Flux
Authors: Mai Pham-Thi Mai Pham-Thi
Published: February 2005

Red calcium sulfide phosphors were prepared using the flux method. Light yellow or pink body colour was obtained for powders synthesized from Na2S
x
or K2S
x
, respectively. The pink colour is related to the absorption band of Eu2+ in the visible region, whereas this band is absent in the yellow powder. Diffused absorption spectra and time-resolved photoluminescent spectra show that europium exists mainly in the trivalent or divalent form for yellow or pink powder, respectively. The presence of Eu3+ in the CaS matrix implies the co-insertion of the flux alkaline ions to respect the electrical neutrality. Because of their similar sizes, Na+ is easily substituted for Ca2+, while K+ can be inserted only in small amounts. Only Eu2+ emission is observed, and the efficiency is nearly the same in both cases. However, the quenching concentration is about one order of magnitude higher (10-2 mol Eu) for the pink powder. The high efficiency observed for the yellow powder may be due to the capture of one electron by Eu3+ leading to excited Eu2+ and to light emission when electron and hole are recombined.
Theory of Polarization Reversals in Ferroelectrics Based on Landau-Type Free Energy
Authors: Yoshihiro Ishibashi Yoshihiro Ishibashi
Published: February 2005

The rate equations based upon the Landau-type free energy function are solved to discuss the polarization reversals in ferroelectrics. The switching time t
s is found to approximately depend upon the applied field E according to a power law, i.e., t
s\proptE
-m
, with m differing according to the definition of t
s. The polarization reversal process fits the Kolmogorov-Avrami formula, where the index n describing the dimensionality of the reversed domains is found to be about 1.3.
Low-Temperature-Induced Oxygen Precipitation Retardation Phenomenon in Czochralski Silicon-Effect of High-Temperature Preannealing and Other Related Phenomena
Authors: Chung-Yuan Kung Chung-Yuan Kung
Published: February 2005

Two-step (low-high) and three-step (high-low-high) annealing experiments were systematically carried out on silicon wafers with both high and low carbon content to study the oxygen precipitation behavior under different thermal cycles. In the two-step anneal, the low-temperature step (750°C for 0-128 h) is for SiO2 precipitate nucleation and the high-temperature step (1050°C for 0-40 h) is for SiO2 precipitate growth. In the three-step anneal, a short wet oxidation cycle precedes the two-step anneal. The thermal history was found to have a great influence on the oxygen microdefects and precipitate morphology, as well as on the carbon reduction behavior. Oxygen precipitation retardation was observed after moderate annealing at low temperature for the two-step-annealed samples. This retardation did not occur in the three-step-annealed samples. It is tentatively concluded that the nuclei of the rodlike defects, which can grow at low temperature but dissolve at high temperature, play a dominant role in the phenomena observed in the two-step anneal.
Preparation of Thin Self-Supporting Metallic Mg Isotope Targets with 50 µg/cm2 Thickness by Rolling Technique
Authors: Fukada Isao Sugai
Published: February 2005

Self-supporting Mg isotope targets as thin as 50 µg/cm2 were prepared by reduction evaporation and rolling techniques from Mg oxide. The foils prepared by this method were satisfactorily pure and uniform and were also strong
enough to resist mechanical shock and for beam irradiation.
Effect of Laser-Induced Dissociation during Measurements of Hydrogen Atoms in Silane Plasmas Using Two-Photon-Excited Laser-Induced Fluorescence
Authors: Park Won Zoo , Tanigawa Manabu , Kajiwara Toshinori , Muraoka Katsunori , Masuda Mitsuharu , Okada Tatsuo , Maeda Mitsuo , Suzuki Atsushi , Matsuda Akihisa
Published: February 2005

During measurements of atomic hydrogen in a silane plasma using two-photon-excited laser-induced fluorescence, laser-induced dissociation of the gas was observed. This was investigated until conditions for the input laser fluence were determined where the effect was negligible. A measurement of the atomic hydrogen distribution was then performed within the limits of these conditions.
Patterning Characteristics of a Chemically-Amplified Negative Resist in Synchrotron Radiation Lithography
Authors: Deguchi Kimiyoshi , Miyoshi Kazunori , Tetsuyoshi Ishii Tetsuyoshi Ishii , Tadahito Matsuda Tadahito Matsuda
Published: February 2005

To explore the applicability of synchrotron radiation X-ray lithography for fabricating sub-quartermicron devices, we investigate the patterning characteristics of the chemically-amplified negative resist SAL601-ER7. Since these characteristics depend strongly on the conditions of the chemical amplification process, the effects of post-exposure baking and developing conditions on sensitivity and resolution are examined. The resolution-limiting factors are investigated, revealing that pattern collapse during the development process and fog caused by Fresnel diffraction, photo-electron scattering, and acid diffusion in the resist determine the resolution and the maximum aspect ratio of the lines and spaces pattern. Using the model of a swaying beam supported at one end, it is shown that pattern collapse depends on the resist pattern's flexural stiffness. Patterning stability, which depends on the delay time between exposure and baking, is also discussed.
GaAs Films Heteroepitaxially Grown on Si Substrates by Mixture Beams of Ions and Molecules
Authors: Tamura Susumu , Tuzi Naohiro , Hyouzou Masahiko , Katsuhiro Yokota Katsuhiro Yokota , Saichi Katayama Saichi Katayama
Published: February 2005

Thin GaAs films were heteroepitaxially grown on Si substrates by mixture beams of 60 eV ions and neutral molecules without prebaking at a high temperature or intermediate layers. Surfaces of the Si substrates were amorphized by collision of the low-energy ions. The amorphous Si surface layers were automatically inserted between Si substrates and GaAs films and they served as a buffer layer to relieve strain due to large lattice mismatch and difference in coefficients of linear expansion between GaAs films and Si substrates.
Epitaxial Growth of SrTiO3 Films on Pt Electrodes and Their Electrical Properties
Authors: Kazuhide Abe Kazuhide Abe , Shuichi Komatsu Shuichi Komatsu
Published: February 2005

Heteroepitaxial SrTiO3 films of perovskite structure with thicknesses of 46 to 184 nm were prepared by rf magnetron sputtering, holding substrate temperature at 400°C, on Pt films which were also epitaxially grown on a MgO(100) substrate in advance. The relative dielectric constant was estimated to be more than 300, and the leakage current density was less than 10-8 A/cm2. The analysis of the leakage current suggests Schottky barrier formation at the interface between SrTiO3 and Pt films, with a barrier height of about 1 V.
The Current-Voltage Characteristics of a Delta-Doped Triple-Barrier Switch
Authors: Su Yan Kuin , Wang Ruey Lue , Ching Hwang Su Ching Hwang Su , Hann Huei Tsai Hann Huei Tsai
Published: February 2005

In this report, a delta-doped triple-barrier regenerative switching device is studied. The device is composed of a p+-n junction in series with a triple-barrier unipolar diode. One barrier is induced by a δn+-i-δp+-i-δn+ structure. The gate electrode is placed on the two barriers near the substrate. Three-terminal voltage-controlled and current-controlled current-voltage characteristics are shown. The ratio V
S/V
H of switching to holding voltage is more than 3 under bias. At positive gate-to-cathode (GC) bias, the switching voltage decreases with the increase of gate bias and then saturates to some value when the bias is more than 0.5 V. The switching phenomena still appear at high positive GC bias. At negative GC bias, holes, trapped in the potential well of holes, are from diffusion current or generated by avalanche breakdown.
Orientation Control of AlN Film by Electron Cyclotron Resonance Ion Beam Sputtering
Authors: Okano Hiroshi , Tanaka Toshiharu , Kenichi Shibata Kenichi Shibata , Shoichi Nakano Shoichi Nakano
Published: February 2005

Orientation control of aluminum nitride (AlN) films deposited on a-SiN/(110)Si was investigated by controlling the assisted nitrogen ion beam. Films were deposited using an electron cyclotron resonance (ECR) dual ion beam sputtering system having an ECR ion gun for irradiation and Kaufman-type ion gun for sputtering. It was found that AlN films with perpendicular and parallel orientation to the substrate could be obtained. These films consisted of micrograins. However, it was confirmed from reflection high energy electron diffraction (RHEED) and selected area electron diffraction (SAED) patterns that the former was c-axis oriented film and the latter was nearly single crystal.
Pb(Zr, Ti)O3 Thin-Film Preparation by Multitarget Magnetron Sputtering
Authors: Hirata Kazuo , Hosokawa Naokichi , Hase Takashi , Sakuma Toshiyuki , Miyasaka Yoichi
Published: February 2005

Ferroelectric lead zirconate-titanate (PZT) thin films have been prepared on Pt-coated oxidized Si substrates (Pt/Ti/SiO2/Si) utilizing a multitarget magnetron sputtering system with three Pb(Zr0.5, Ti0.5)O3 targets and one PbO target. Crystal structure and dielectric properties of the films have been studied as functions of substrate temperature (T
s) and Pb content. The Pb content in the film has been precisely controlled by optimizing the rf input power for the PbO target (P
PbO). As a result, single-phase perovskite films have been prepared fairly easily with appropriate combinations of T
s and P
PbO. A film with atomic ratios of Pb/(Zr+Ti)=1.3 and Zr/(Zr+Ti)=0.5 prepared at T
s=600°C exhibited a dielectric constant of 780 and remanent polarization of 19 µC/cm2.
Crystalline Structure of PbTiO3 Thin Films by Multiple Cathode Sputtering
Authors: Maiwa Hiroshi , Ichinose Noboru , Kiyoshi Okazaki Kiyoshi Okazaki
Published: February 2005

The preparation of PbTiO3 thin films by multiple cathode rf-magnetron sputtering was investigated. The effects of incident Pb/Ti ratio, the kind of substrates, substrate temperatures and film thickness on the crystalline structure of the PbTiO3 thin films prepared were studied. The thin films with perovskite PbTiO3 structure on Si wafers were obtained by deposition at an incident Pb/Ti ratio of 1.2 at a substrate temperature of 460∼500°C. The X-ray photoemission spectroscopy (XPS) depth profile revealed that less reaction of the thin films with the Si substrate was observed at the interface at lower substrate temperatures.
Propagation Characteristics of Lamb Waves in PbZrO3-Based Ceramic Substrate
Authors: Sugizaki Goro , Takenaka Tadashi , Toda Koichiro Sakata
Published: February 2005

The piezoelectric and dielectric constants of a PbZrO3-based ceramic substrate and the propagation characteristics of Lamb waves are described. The Lamb wave phase velocities are analyzed numerically under various electrical and mechanical boundary conditions. The numerical results confirmed experimentally are given in the form of a function of the product of the wave number and the substrate thickness, which suggest that a Lamb wave device can be constructed to operate in a single mode as well as in multimodes. The S0 mode Lamb wave device shows satisfactory performance as a single-mode operation.
Mechanism of Memory Effect in an Organic Photoreceptor Coated on an Organic Polymer Electrode
Authors: Nakazawa Yusuke , Ito Nobuhiro , Hoshino Katsuyoshi , Jun-ichi Hanna Jun-ichi Hanna , Hiroshi Kokado Hiroshi Kokado
Published: February 2005

A photoinduced memory effect in an electrophotographic receptor consisting of an iodine-doped conductive polymer electrode and a poly(N-vinylcarbazole) (PVK)/trinitrofluorenone (TNF) photoreceptor was investigated by means of xerographic, voltage-current and electrochemical measurements. The results showed that activation energy for memory formation was about 0.23 eV and was associated with the energy for CT-complex formation of PVK and iodine. This led us to propose a mechanism of memory formation in this system. Accordingly, it was indicated that the memory lifetime could be controlled by varying the kind of hole-transport material interacting with iodine.
Vibration-Level Characteristics of Lead-Zirconate-Titanate Ceramics
Authors: HIROSE Sadayuki Takahashi
Published: February 2005

Vibration-level characteristics of lead-zirconate-titanate ceramics were studied using the constant current driving method. It was found that resonant frequency and mechanical Q markedly decreased with increasing vibration level, accompanying heat generation. The heat generation was assumed to be caused by vibration loss. The vibration loss was reduced by doping Fe atoms to the ceramics. On the contrary, the vibration loss was increased by doping Nb atoms.
Effects of Manganese Addition on Piezoelectric Properties of Pb(Zr0.5Ti0.5)O3
Authors: Kamiya Toshio , Suzuki Toshimasa , Takaaki Tsurumi Takaaki Tsurumi , Masaki Daimon Masaki Daimon
Published: February 2005

The effects of MnO2 addition on k
31 and Q
m were investigated for Pb(Zr0.5Ti0.5)O3(PZT). The MnO2 addition increased Q
m and k
31 in a low poling field. This result indicated that Mn-doped PZT possessed properties of `soft' and `hard' piezoelectrics simultaneously. Electron spin resonance measurement indicated that Mn2+, Mn3+ and Mn4+ coexisted in PZT. The tetragonality of the PZT lattice and the Curie temperature decreased with MnO2 content. From these results, it was found that the increase in k
31 of Mn-doped PZT was due to the change of the crystal structure toward a cubic system, and the increase in Q
m to Mn2+ and Mn3+ ions working as acceptor dopants. The characteristic feature of Mn is that its addition to PZT decreases tetragonality, and various valence states coexist in proper ratio in Mn-doped PZT sintered in atmosphere.
Temperature Dependence of a Bimorph-Type Actuator Using Lead Zinc Niobate-Based Ceramics
Authors: Noriko Yamamoto Kudo Noriko Yamamoto Kudo , Tomio Ono Tomio Ono
Published: February 2005

Displacement characteristics for a bimorph-type actuator, made with lead zinc niobate-based (PBZM) ceramics were investigated at temperatures from -20°C to 60°C by driving the actuator with the bias driving method. Displacement was found to depend on both the temperature and the bias electric field; in particular, the temperature dependence of displacement can be improved by increasing the bias field strength. It was found that this displacement dependence is closely related to the relative dielectric constants of the ceramics.
Piezoelectricity and Electrostriction in Ferroelectric Actuators
Authors: Kurihara Atsushi , Nomura Koji , Ken-ichi Hirota Ken-ichi Hirota , Takuro Ikeda Takuro Ikeda
Published: February 2005

Large amplitude driving of ferroelectric actuators has been investigated. Displacement ξ, electric charge Q and current I were measured with varying alternating voltage V
AC at various frequencies f (120, 500 and 1000 Hz) under voltage bias V
bias (0 to 75 V). Effective piezoelectric and dielectric constants were evaluated from initial slopes of ξ and Q vs V
AC, respectively. It is concluded that 90° domain reorientation makes some contribution to linear electromechanical interaction even when the strain level is low. It seems difficult to distinguish electrostriction from piezoelectricity.
Bending Actuator Using Lead Zirconate Titanate Thin Film Fabricated by Hydrothermal Method
Authors: Kikuchi Takayuki , Tsurumi Takaaki , Yoko Ohba Yoko Ohba , Masaki Daimon Masaki Daimon
Published: February 2005

Thin films of lead zirconate titanate (PZT) were fabricated by the hydrothermal method which consisted of two steps in the hydrothermal process: “nucleation” and “crystal growth” processes. The PZ nuclei were formed by the reaction at 140°C in a solution containing 4N potassium hydroxide. The growth rate of PZT crystals decreased at temperatures below and above 120°C. Bimorph-type bending actuators were made using as-deposited PZT films. The actuators showed large and visible electric-field-induced displacement even at driving voltage less than 10 V. From the displacement-voltage curve of an unimorph actuator and that of a heat-treated specimen, it may be concluded that the polar axes of PZT crystals had an orientation toward the substrate, giving rise to the piezoelectric effect without poling procedure.
Fluorine Kα X-Ray Emission Spectra from Selected Metal Fluorides
Authors: Chikara Sugiura Chikara Sugiura
Published: February 2005

With a high-resolution two-crystal vacuum spectrometer, the fluorine Kα emission spectra in fluorescence are measured for AlF3, CrF3·xH2O, FeF3·xH2O, NiF2·4H2O, ZrF4, NH4NbF6and a series of rare-earth trifluorides RF3(R=La, Ce, Pr, Nd, Sm, Eu and Gd). The measured emission spectra consist of a prominent peak and its high-energy satellites. It is shown that the presence of the K1L1satellite peak arising from the 1s-12p-1initial state is unclear in LaF3, CeF3, PrF3and NdF3, in contrast to that of other metal fluorides. This unclear presence is attributed to the F 2p shell vacancy rearrangement through interatomic electronic transitions before 1s hole filling for fluorine Kα emission. The emission spectra of LaF3and CeF3are compared with the XPS spectra of the F-2p valence bands obtained by Sato. There is a good agreement between them.
Dielectric Properties of Lead-Based Complex-Perovskite Solid Solution Pb(In(1-x)/2Ybx/2Nb1/2)O3
Authors: Naohiko Yasuda Naohiko Yasuda , Masanari Fujie Masanari Fujie
Published: February 2005

Lead based-complex perovskite solid solutions Pb(In(1-x)/2Yb
x/2Nb1/2)O3 were prepared through wolframite phase oxides (InNbO4 and YbNbO4), and their dielectric properties were investigated. For Yb concentrations x<0.20, the diffuse phase transition, which was characterized by the broad maximum for the temperature dependence of the permittivity and the dielectric dispersion in the transition region was observed. With increasing x, the maximum permittivity increases. For x>0.20, in addition to the dielectric dispersion, a new frequency-independent dielectric anomaly appears at temperature T
t. With increasing x, T
t increases rapidly and the dielectric dispersion decreases. There is a structural change which is characterized by the splitting of the structure-sensitive maximum of the (200) reflection of X-ray diffraction (XRD) patterns around x=0.20. Thus, the morphotropic phase boundary exists at around x=0.20.
Dielectric Properties and Crystal Structures in Ternary System Pb(Mg1/2W1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3 Ceramics
Authors: Furuya Mitsuru , Mori Toru , Ochi Atsushi , Saito Susumu , Takahashi Seiji
Published: February 2005

Over the entire range of composition in ternary system Pb(Mg1/2W1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3 (PMW-PNN-PT), crystal structures and dielectric properties were investigated. On the compositional line of 30 mol% PNN content, dielectric relaxation, D-E hysteresis loop and long-range order parameter were measured in order to understand the effect of PMW content. From the results, a morphotropic phase boundary (MPB) was found on the compositional line with 45 to 50 mol% PT content. It was found that the PMW component was incorporated into ordered clusters in solid solutions in a PMW-rich compositional region. The degree of ordering was evaluated by the long-range order parameter S. The relationship between the long-range order parameter S and dielectric properties, especially compositional dependence of Curie temperature, in this system was discussed.
Fraunhoffer Diffraction of Electrons in Anisotropic Media
Authors: Kawamura Kiyoshi , Tsuyoshi Ueta Tsuyoshi Ueta , Hiroyuki Sawano Hiroyuki Sawano
Published: February 2005

Diffraction of electrons injected into an open space from a narrow channel is discussed in comparison with the Fraunhoffer diffraction of ordinary lights. The Kirchhoff-Huygens theorem is invoked and modified slightly to solve the boundary value problem in the tight-binding approximation for electrons in solids in the presence of magnetic fields. The Fraunhoffer diffraction pattern is affected significantly by the transversal motion within the waveguide and it usually has two peaks when the electron wave belongs to a single transverse mode. The calculation with the billiard model is interpreted from a point of view of the wave mechanics.
Grain Size Dependence of Optical Transmittances and Linear Electrooptic Coefficients of Hot-Pressed Ba(La1/2Nb1/2)O3-PbZrO3-PbTiO3 Ferroelectric Ceramics
Authors: Yokosuka Masaru , Ochiai Tutomu , Masakazu Marutake Masakazu Marutake
Published: February 2005

In order to study the grain size dependence of optical transmittances and linear electrooptic coefficients of the ferroelectric ceramics with the composition 0.1Ba(La1/2Nb1/2)O3-0.9Pb(Zr0.5Ti0.5)O3, specimens having various grain sizes were prepared by the hot-pressing method under different sintering conditions, namely by varying the temperature, the time and the pressure, independently. The results obtained show that the transmittance increases as the grain size increases, and that it decreases very slightly in the phase change from the paraelectric to the ferroelectric tetragonal phase. The linear electrooptic coefficient r
c shows a slight decrease with increasing grain size.
Anomalous Photovoltaic Current and Diffraction Efficiency in LiNbO3 Single Crystals
Authors: Chen Zhiming , Shyuichi Nagata Shyuichi Nagata , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

In this paper we report the experimental and theoretical result that the photorefractive properties of pure and doped lithium niobate single crystals show a close relationship with anomalous photovoltaic (APV) current. The dopant dependence of sensitivity of two-wave mixing is discussed with the APV current in theory. The product of quantum efficiency and effective drift length ΦL
ph is obtained.
Compensation for Ferroelectric Hysteresis Loop Distortion and Its Application to Phase Transition Studies
Authors: Hatano Jun , Takeuchi Hiroshi , Watanabe Masato Harazaki
Published: February 2005

A compensation for ferroelectric hysteresis loop distortion has been developed and applied to some ferroelectric or antiferroelectric phase transitions. The distortion of loop has been numerically synthesized on the basis of an equivalent circuit and subtracted from the measured signal; in the calculation, nonlinearity of the circuit can be taken into account as necessary. Successful results were obtained in ferroelectrics near the second-order phase transition and in antiferroelectrics which show nonlinear conductivity or a nonlinear dielectric constant.
Influence of Photorefractive Effect on Piezoelectric Vibration
Authors: Ohki Michio , Nobuyuki Taniguchi Nobuyuki Taniguchi , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

Strong nonlinear behavior was observed in a LiNbO3:Fe piezoelectric resonator with a photorefractive periodic grating. The resonator is a y-cut plate with Au electrodes totally or partially deposited on both faces. The current-voltage and the admittance-frequency characteristics show nonlinear behavior such as hysteresis only near the resonance frequency. In some conditions, the current changes negatively with the voltage. These characteristics depend on the Q-value of the resonator. The present nonlinear phenomena do not occur when the Q-value is too large, while they occur at larger values of Q in usual resonators. We found that the Q-value of the resonator with the photorefractive grating varied when the resonator was annealed or when the period of the grating was changed.
Dielectric Breakdown Strength of Grain-Oriented Bi4Ti3O12 Ceramics
Authors: Kazuo Shoji Kazuo Shoji , Yasuo Uehara Yasuo Uehara
Published: February 2005

DC dielectric breakdown strength Eb of grain-oriented Bi4Ti3O12 ceramics fabricated by the hot-forging method and the cold-uniaxial pressing method has been studied. In the hot-forging sample with the X-ray orientation factor of 0.84, Eb was about 22 MV/m, when electric field was applied parallel to the pressing axis of the grain-oriented ceramics. On the other hand, Eb was about 16 MV/m, when the field was perpendicular to the pressing axis. It was found that grain orientation is effective in increasing Eb parallel to the pressing axis.
Hysteresis Loops in Ferroelectrics Undergoing an Isomorphous Phase Transition
Authors: Yoshihiro Ishibashi Yoshihiro Ishibashi
Published: February 2005

Ferroelectric hysteresis loops are discussed in terms of free energy expanded to the eighth order in polarization. For suitable choice of the coefficients, deformed triple hysteresis loops will be observed. There is a possibility that such deformed loops are utilized for nondestructive readout memory.
Reversible Reconstruction Changes in GaAs Surfaces due to Hydrogen Termination
Authors: O'keeffe Patrick , O'morain Ciaran , Komuro Shuji , Ishii Masashi , Meguro Takashi , Iimura Yasufumi , Den Shoji , Morikawa Takitaro , Aoyagi Yoshinobu
Published: February 2005

Hydrogen plasma beam irradiation effects on the surface reconstruction of GaAs substrates are investigated. Successful low temperature removal of the GaAs oxide layer using hydrogen plasma beam irradiation is carried out, and the subsequent reflection high energy electron diffraction (RHEED) observation of the reversible surface reconstruction changes is observed. This reversible surface reconstruction effect is explained in terms of the atomic hydrogen termination of the As dangling bonds.
The Initial Susceptibility of Grain Oriented (110)[001] Silicon Steel
Authors: Hans Hauser Hans Hauser
Published: February 2005

A new method for detecting the initial susceptibility of ferromagnetic materials by recording of an induced voltage is discribed and applied for measurements on grain oriented silicon steel in three crystallographic directions. The results can be interpreted by the magnetization process and are compared with the ascent of M-H-virgin curves (dc-fields) recorded under same conditions.
The Effects of Boron on the Microstructure and the Magnetic Properties of Rapid Quenched Fe-Pt Alloy Systems
Authors: Yung Shei-Wen , Yen-Hwei Chang Yen-Hwei Chang , Ming-Pan Hung Ming-Pan Hung
Published: February 2005

The structure and magnetic properties of the rapid quenched binary Fe100-x
Pt
x
and ternary (Fe0.6Pt0.4)100-y
B
y
alloys ribbons were investigated. The ribbons of both the alloy systems exist as the so-called “lamellar structure” of the γ1 phase. Boron would change the composition of the order of the γ1 phase, which coexists with Fe2B in ternary alloy ribbons, and cause the actual Pt content in the γ1 phase of the ternary alloys to rise. The result was that the high-temperature γ phase was difficult to obtain in the as-quenched state. Coercivity increase due to boron addition was remarkable for precipitating a number of small Fe2B particles at the grain boundary of the γ1 matrix retarding the growth of γ1 grains during annealing and acting as pinning sites of domain wall motion.
Plasma-Enhanced Chemical Vapor Deposition of Silicon Nitride
Authors: Kobayashi Ikunori , Tetsu Ogawa Tetsu Ogawa , Sadayoshi Hotta Sadayoshi Hotta
Published: February 2005

The optimum condition of plasma-enhanced chemical vapor deposition to deposite silicon nitride (SiN
x
) film and its application as a gate insulator of a-Si thin-film transistor (TFT) have been investigated. The internal stress of SiN
x
in the range of 4.3×109 dyn/cm2 tensile to 8.0×109 dyn/cm2 compressive is found to be controllable by changing the ratio of H2 and N2 in the source gases without affecting the optical band gap. Satisfactory TFT characteristics and high reliability are realized by using a gate insulator of SiN
x
having either stoichiometric or N-rich composition which shows the large optical band gap.
Photorefractive Gain Dependence on Diffraction Efficiency in Bi12SiO20 Crystal
Authors: Shibatoko Takeharu , Tanimoto Takeshi , Ishibashi Hiroyuki , Masafumi Yamashita Masafumi Yamashita , Toshiharu Tako Toshiharu Tako
Published: February 2005

Photorefractive gain in Bi12SiO20 (BSO) crystal was studied using a two-wave mixing configuration. It was clear that the gain was strongly dependent on the incident plane in the BSO crystal rotated clockwise around the <11̄0> direction where the rotation angle of zero coincided with the <001> direction. There were two regions in the gain, i.e., the gain was negative in the range of 10°∼170° and positive in the range of 190°∼350°. The energy exchange between two coherent beams could be explained by the diffraction efficiency of the diffracted beam being a function of the rotation angle of the crystal. The experimental results agreed well with the theoretical results.
Polymer Dispersed Liquid Crystal Films with Memory Characteristics
Authors: Fuh Andy Ying-Guey , Li Tsung Chih Ko
Published: February 2005

Polymer dispersed liquid crystal (PDLC) films with memory electrooptical characteristics were fabricated. The approach made use of phase transition characteristics of smectic liquid crystals. If a smectic is cooled from the nematic to the smectic state in the presence of an electric field, one obtains an aligned smectic. This structure yields a transparent state. However, if the material is cooled in the absence of the field, it adopts a focal conic texture which yields a light-scattering state. The fabrication of these devices, together with their measured electrooptical characteristics, is reported.
Relaxation Processes of Two Glass Transitions for a Zr60Al15Ni25 Amorphous Alloy
Authors: Okumura Hiroshi , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

The relaxation behavior for the glass transition of a Zr60Al15Ni25 amorphous alloy with a wide supercooled liquid region is investigated through the changes of dynamic mechanical properties. Temperature-dependent storage and loss moduli reveal two relaxation systems suggesting two glass transitions. The activation energies are 400 and 420 kJ/mol for the lower and the higher temperature relaxations, respectively. Both of these relaxations have wider distribution of the relaxation time than that of the single relaxation of the Debye peak. The appearance of the two relaxation systems is attributed to the phase separation in the amorphous phase observed in the electron micrograph.
Toward Epitaxial Growth of CuGaS2 on GaAs(001) Substrate by Chloride Chemical Vapor Deposition
Authors: Pu Yong Shen , Takamasa Kato Takamasa Kato , Takashi Matsumoto Takashi Matsumoto
Published: February 2005

Growth conditions for achieving epitaxy of CuGaS2 on GaAs (001) substrates by chloride chemical vapor deposition have been discussed. The a-axis growth, which should be excluded for epitaxial growth, was suppressed by lowering substrate temperatures and by reducing carrier gas flow rates during a heating up period before the beginning of layer growth.
Nuclear Data Measurements for Yttrium Isotope Used for Activation Analysis and Neutron Metrology
Authors: Tarek Elnimr Tarek Elnimr
Published: February 2005

In order to establish more accurate nuclear data for the yttrium isotope 89Y, joint experimental work has been conducted in four greatly different thermal-to-epithermal neutron flux ratios (Q
th/Q
epi). After carefully calibrating the neutron spectra in the irradiation channels used, nuclear constant K
0, K
e,0 and Q
0 remeasured and found to be: for E=202.5 keV K
0=2.33×10-5 (1.9%), K
0 according to the Cd-subtraction method=2.31×10-5 (1.7%) and K
e,0=8.76×10-6 (2%) for E=479.5 keV K
0=2.19×10-5 (2%), K
0 according to the Cd-subtraction method=2.18×10-5 (1.9%), and K
e,0=8.30×10-6 (2%) and Q
0=6.20 (2.1%). The relevant effective resonance energies Ē
r have been recalculated using the latest BNL neutron resonance parameters yielding Ē;r (89Y)=4302 eV (7%). The half life of the 90mY isotope has also been remeasured to give T1/2 (90mY)=3.185 h (0.5%) with 1σ limit.
Evaluation of Dry Chemicals by Photoacoustic Imaging
Authors: Tsutomu Hoshimiya Tsutomu Hoshimiya
Published: February 2005

In this study, an apparatus suitable to photoacoustic (PA) imaging to measure blood-analysis and urinalysis is fabricated and its measurement scheme has been established for the first time. The PA imaging of urinalysis test strip, blood sugar test strip, and cholesterol test strip is performed. A calibration curve of PA measurement is obtained for a urine test strip. The detectivity is better than that obtained by an eye-measurement.
Microscopy Studies for the Deep-Anisotropic Etching of (100) Si Wafers
Authors: Ju Byeong Kwon , Ha Byeoung Ju , Kim Chul Ju , Tchah Myung Hwan Oh
Published: February 2005

Several etching phenomena appeared during the Si membrane process were observed and analyzed. In case of deep etching to above 300 µm depth, the etch-defects existed at the etched surface could be classified into three categories such as hillocks, adhered reaction products and white residues. It was known that the hillocks had a pyramidal shape or trapizoidal hexahedron structures depending on the density and size of the reaction products. Also, the existence of etch-defects and the etch rate distribution over a whole 4-inch wafers were investigated when the surfaces to be etched were downward, upward horizontally and erective for the stirring bar in the solution. As the results, the downward and erected postures were favorable in the etch rate uniformity and the etch-defect removal, respectively.
Development of New a-Si/c-Si Heterojunction Solar Cells: ACJ-HIT (Artificially Constructed Junction-Heterojunction with Intrinsic Thin-Layer)
Authors: Tanaka Makoto , Taguchi Mikio , Matsuyama Takao , Sawada Toru , Tsuda Shinya , Nakano Shoichi , Hanafusa Hiroshi , Kuwano Yukinori
Published: February 2005

A new type of a-Si/c-Si heterojunction solar cell, called the HIT (Heterojunction with Intrinsic Thin-layer) solar cell, has been developed based on ACJ (Artificially Constructed Junction) technology. A conversion efficiency of more than 18% has been achieved, which is the highest ever value for solar cells in which the junction was fabricated at a low temperature (<200°C).
Se Segregation and Chemical Bonding in Pd/Se/GaAs
Authors: Berrigan Rebecca , Watanabe Yoshio , Tom Scimeca Tom Scimeca , Masaharu Oshima Masaharu Oshima
Published: February 2005

The chemical bonding and surface segregation of the Pd/Selenium-passivated GaAs interface is monitored by synchrotron radiation photoemission spectroscopy (SRPES). Pd deposition on GaAs(100) and (111)A is accompanied by Se segregation into the Pd overlayer preventing As segregation. Moreover, Se atoms are found to remain at the Pd/GaAs(111)B interface and may play a role in suppressing GaAs substrate disruption during metal deposition.
Study of YBCO/Au Surface Using Low-Temperature Scanning Tunneling Microscopy/Scanning Tunneling Spectroscopy
Authors: Koyanagi Masao , Kashiwaya Satoshi , Akoh Hiroshi , Kohjiro Satoshi , Matsuda Mizushi , Fuminori Hirayama Fuminori Hirayama , Koji Kajimura Koji Kajimura
Published: February 2005

A low-temperature scanning tunneling microscope (LTSTM) has been used to study the surface electronic state of a 30-nm-thick Au film deposited on (103)-oriented YBCO thin film. Conductance spectra with the BCS-like dip induced by the superconductivity proximity effect were observed in a small area. Also, spectra with zero-bias conductance peaks were observed in another limited area. Most parts of the areas studied showed constant conductance spectra. Since this fact suggests the existence of a degraded layer on most surfaces of the YBCO film, the Josephson coupling in YBCO/Au/Nb is assumed to occur primarily in this degraded layer.
Displacement Damage Effects and Related Phase Changes of Ar-Ion-Irradiated BiSrCaCuO System Superconducting Thin Films
Authors: Kazuo Saito Kazuo Saito , Masatsugu Kaise Masatsugu Kaise
Published: February 2005

BiSrCaCuO thin films of 0.5 µm thickness containing mainly the high-T
c phase were irradiated with 100 keV Ar ions up to 5×1017 ions/cm2 at 10 K or 300 K. The irradiated thin films were considered to consist of a heavily damaged surface layer and an underlying partly displaced crystalline layer. The transition temperature T
c of the films decreased initially with increasing Ar ion dose and converged at about 63 K for doses larger than 1×1017 ions/cm2. By a subsequent annealing below 800°C, the T
c recovered up to 98 K. The relative X-ray diffraction intensity of the high-T
c phase reached a maximum upon annealing at 700∼730°C. During the annealing, the heavily damaged or amorphous surface layer recrystallizes and regrows into better quality high-T
c phase particles with concomitant formation of the thermodynamically stable Ca-free phase at this low temperature range.
Thermal Spike and Displacement Damage Effects in BiSrCaCuO Thin Films by Ar Ion Beams
Authors: Kazuo Saito Kazuo Saito , Masatsugu Kaise Masatsugu Kaise
Published: February 2005

Superconducting BiSrCaCuO thin films containing both low-T
c, 80 K phase and high-T
c, 108 K phase material were irradiated with 100 keV Ar ions up to 4×1017 ions/cm2 at 10 K and 300 K. In-situ resistivity measurements revealed that in the early stage of Ar ion irradiation at 10 K the superconducting state of the films was maintained, but was destroyed after prolonged irradiation to a dose of 1×1015 ions/cm2. The normal-state resistivity of the high-T
c phase increased with ion dose at a smaller rate than that of the low-T
c phase. A thermal spike model was suggested in which the constituent atoms are thermally activated to rearrange themselves and form high-T
c phase embryos under the irradiated conditions. The growth of the high-T
c embryos occurred efficiently by subsequent annealing at 700∼730°C, improving the high-T
c phase ratio markedly.
Extensive Structural Investigations of M(HCO2)2·2(NH2)2Co (M=Mg, Mn, Zn, Co and Cd) in view of Two-Dimensional Magnetic Interactions
Authors: Ridwan Ridwan
Published: February 2005

The crystal structures of M(HCO2)2·2(NH2)2CO (M=Mg, Mn, Zn, Co and Cd) have been extensively determined by an X-ray diffraction method, with special interest in the two-dimensional magnetic interactions. All of the compounds in the family show a common structure that consists of infinite square planar networks of [M(HCO2)2]4 sustained through the hydrogen bonds by urea molecules. No direct covalent interaction was observed between the metal ions in adjacent layers. Hence, in the case of magnetic compounds, the two-dimensional superexchange interaction in the three-dimensional framework is practically actualized. For the sake of comparison, the structure of Co(HCO2)2·2H2O was also determined, however, the interaction mechanism was found to be normally three-dimensional.
Circular Free-Electron Laser Using Velvet-Covered Cathode
Authors: Sekita Hitoshi , Mizuno Takahide , Ohta Hiroshi , Kitora Masakazu , Yoshihiko Naito Yoshihiko Naito , Hirobumi Saito Hirobumi Saito
Published: February 2005

Generation of microwave radiation from a rotating electron beam in a circular wiggler magnetic field (circular free-electron laser) has been studied. The electron beam is emitted by a velvet-covered cathode; its energy is typically 300-500 keV and its beam current is 160 A. Measured frequency, power and pulse width of the radiated microwave are 12.7 GHz, 11 kW and 500 ns, respectively. Measured frequency agrees with the theoretical prediction. The interaction between the beam mode and the traveling magnetic waveguide mode is discussed based upon the dispersion relation.
A New Method of Photothermal Displacement Measurement by Laser Interferometric Probe -Its Mechanism and Applications to Evaluation of Lattice Damage in Semiconductors
Authors: Sumie Shingo , Takamatsu Hiroyuki , Nishimoto Yoshiro , Horiuchi Takefumi , Nakayama Hiroshi , Kanata Takashi , Nishino Taneo
Published: February 2005

A new, highly sensitive technique for measuring photothermal displacement using a laser heterodyne interferometric probe has been developed. This technique is based on the detection of phase changes in the probe beam and is very sensitive to the presence of lattice damage in semiconductors. It has been found that the phase change is caused by the thermal expansion of a sample surface induced by absorption of a modulated pump beam. The displacements of metals and semiconductors measured by this technique coincided with the results predicted by a thermal diffusion model. These displacements simply depended upon the ratio of the thermal expansion coefficient to the thermal conductlvity of a sample.
Deposition of Aluminum-Doped Zinc Oxide Thin Films by Spray Pyrolysis
Authors: Goyal Devendra , Solanki Parag , Marathe Balkrishna , Murlidhar Takwale Murlidhar Takwale , Vishnu Bhide Vishnu Bhide
Published: February 2005

Aluminum-doped zinc oxide films were prepared on Corning 7059 by an inexpensive spray pyrolysis technique. Variation in structural, electrical and optical properties with doping concentration is investigated in detail. The films were highly transparent to the visible radiation and electrically conductive.
X-ray diffraction results show that all films were polycrystalline in nature with [002] preferred orientation. Texture coefficient and grain size were calculated along the [002] direction for all films with different doping concentrations. Carrier concentration and mobility values were determined by measuring the Hall voltage at room temperature. Good correlation between structural and electrical properties was found.
Conduction Current Relaxation of Inhomogeneous Conductor III
Authors: Namikawa Kazunao Yamamoto
Published: February 2005

The conditions in which the conducting path structure simulates the low-frequency dielectric relaxation of oxide glass were investigated on the basis of considerations of the ratio of the initial and steady-state currents, the relation between the magnitude of the relaxation and the potential energy, and a numerical calculation using an approximation. Conclusions are as follows: (1) The shape of the conducting path is complicated. (2) The intensity of the local field at the steady state is distributed exponentially and its ratio of the maximum to the minimum is large. (3) It is expected that the conducting path structure of the interconnected structure type simulates the low-frequency dielectric relaxation of oxide glass.
Dynamic Measuring Method of Capacitance Variation of Piezoelectric Ceramics with Alternating Electric Field
Authors: Yasuo Cho Yasuo Cho , Fumihiko Matsuno Fumihiko Matsuno
Published: February 2005

The development and application of a new dynamic measuring method of capacitance variation of piezoelectric materials, especially of lead zirconate titanate (PZT) ceramics, with an alternating electric field are presented. This method makes it possible to separate the capacitance variation due to nonlinear effect from that due to temperature change, to obtain the adiabatic nonlinear coefficients, to fix the sign of the nonlinear coefficient, and to determine each order of coefficients, separating the orders of the capacitance variation as a function of the applied electric field.
Investigation and Handling of Langmuir-Blodgett Polyimide Alignment Layers for Surface-Stabilized Ferroelectric Liquid Crystal Displays
Authors: Rupp Thomas , Matthias Eberhardt Matthias Eberhardt , Hans Gruler Hans Gruler
Published: February 2005

Handling of polyimide-Langmuir-Blodgett (PI-LB) alignment layers for surface-stabilized ferroelectric liquid crystal (SSFLC) cells is optimized and investigated. Different kinds of indium tin oxide substrates are compared with respect to surface roughness and structure by scanning tunneling microscopy. The decrease of surface corrugation by depositing single PI-LB layers is shown. Orientation of PI monolayers can be measured by optical retardation. Orientation after LB coating exists only with small substrates. With bigger ones, additional rubbing is necessary. The order parameter for LB layers induced by rubbing is calculated. The perfect alignment properties can be seen in bistable high-contrast SSFLC matrix cells. A new method of removing zigzags (ZZs) is introduced, and the physical reason for it is found in the electromechanical effect.
A Novel Method of Beryllium Window Protection in a Plasma Focus Soft X-Ray Source
Authors: Kato Yasuo , Ochiai Isao , Sato Toshihiko , Murayama Seiichi , TAniguchi Motoya , Funatsu Ryuichi
Published: February 2005

A significant problem of plasma X-ray sources such as a plasma focus device is how to protect the very thin beryllium window from damage and contamination caused by the bombardment of plasma particles. Improvement of the protection of the beryllium window has been made by inserting a magnetic deflector between the focused plasma and the window and by inverting the polarity of the applied voltage to the electrodes. As a result, a 13-µm-thick beryllium membrane can be used safely. The measured X-ray intensity is about 5 mW/cm2 30 cm from the source operated at 3.5 kJ discharge energy. The achieved intensity is suitable for R&D application in X-ray lithography.