bluuebunny/crossref_metadata_2025 huggingface dataset:
The Identification and Suppression of Defects Responsible for Electrical Hysteresis in Metal-Nitride-Silicon Capacitors
Authors: Lau W. S.
Published: February 2005

An attempt was made to correlate the hysteresis in high frequency capacitance-voltage (C-V) measurements on metal-nitride-silicon (MNS) capacitors and spin density measured by electron spin resonance (ESR) spectrometry on a series of silicon-rich and nitrogen-rich silicon nitride films deposited by plasma enhanced chemical vapor deposition (PECVD). We found that the hysteresis Δ
V
H in the C-V characteristics can be divided into Δ
V
+, which corresponds to negative charge trapping, and Δ
V
-, which corresponds to positive charge trapping. A one-to-one correlation was found between Δ
V
+ and the spin density attributed to the silicon dangling bond. However, Δ
V
- was nearly constant even though the spin density changed by two orders of magnitude. Nevertheless, Δ
V
- was found to be significantly reduced by an ammonia plasma treatment of the silicon substrate before the silicon nitride deposition. These observations support the hypothesis that besides the silicon dangling bond, which can be suppressed by using nitrogen-rich films instead of silicon-rich films, there is another important type of defect probably at the nitride-silicon interface, which can be suppressed by an appropriate ammonia plasma treatment.
Shubnikov-de Haas Oscillations in a Narrow GaAs/AlGaAs Wire
Authors: Ochiai Yuichi , Mizuno Masahiro , Kawabe Mitsuo , Ishibashi Koji , Aoyagi Yoshinobu , Gamo Kenji , Namba Susumu
Published: February 2005

Low-temperature magnetoresistances of a narrow GaAs/AlGaAs wire have been measured down to 0.3 K at magnetic fields of up to 8 T. A deviation from the straight Fan plot has been observed in Shubnikov-de Haas (SdH) oscillations of the magnetoresistance. Comparing the amplitude of the oscillations with the theoretical estimation, the deviation corresponds to a change in the single-particle relaxation time. The change suggests a modification of electron wave propagation in high magnetic field.
Measuring the Oxygen Diffusion in C-Axis Oriented ErBa2Cu3Ox Films Using In Situ X-ray Diffraction Technique
Authors: Narumi Eiki , Shaw David T. , Matsui Masakazu , Yamamoto Kiyoshi
Published: February 2005

An in situ X-ray technique was used to study the diffusion of oxygen in c-axis oriented ErBa2Cu3O
x
films made by rf magnetron sputtering. The diffusion is mainly parallel to the c-axis of the film, and the coefficients for oxygen diffusion are estimated to be in the order of 10-14 and 10-12 cm2·s-1 at annealing temperatures of 500°C and 900°C, respectively.
Fabrication of High Tc 2223 (Bi, Pb)SrCaCuO Single-Phase Films by Single-Target RF Magnetron Sputtering and Postannealing
Authors: Lin S. L. , Tien C. , Chin T. S. , Huang T. W. , Hung M. P.
Published: February 2005

Single-phase 2223 Bi(Pb)-Sr-Ca-Cu-O superconducting films with T
czero
above 100 K were reproducibly obtainable by single-target (Bi20Pb3Sr16Ca25Cu36O
z
) rf magnetron sputtering on (100) MgO and postannealing. During annealing, the films were placed face-down on top of bulk material with different Pb contents. It was found that the optimal conditions for the annealing of 600-nm-thick films to obtain the aingle 2223 phase were 845°C for 12 to 14 hours on top of bulk Bi19.5Pb3.5Sr22Ca22Cu33O
z
bulk. The thinner the film was, the shorter was the optimal annealing time, at the expense of broadened T
c transition.
Resputtering Effect on Y1Ba2Cu3O7-d Thin Films Prepared by RF-Magnetron Sputtering
Authors: Enami Hiroyoshi , Shinohara Toshiyuki , Kawahara Nobuaki , Kawabata Sanemasa , Hoshizaki Hiroki , Imura Toru
Published: February 2005

Y1Ba2Cu3O7-δ thin films were prepared on MgO(001) substrates by rf-magnetron sputtering. The influence of oxygen partial pressure on film preparation has been investigated quantitatively. The oxygen flow rate near the substrate was controlled by an oxygen inlet ring. As-deposited films in an appropriate condition of oxygen flow rate show a superconducting transition at 83 K. When too much oxygen gas is introduced into a chamber, as-deposited films are damaged by resputtering and their superconducting property disappears. The growth mechanism of the thin films is discussed in terms of the resputtering effect.
FTO/SnSe Heterojunction for Photovoltaic Conversion
Authors: Singh J. P. , Bedi R. K.
Published: February 2005

FTO/SnSe heterojunctions have been fabricated onto glass substrates. It has been observed that photocurrent shows a maximum around 735 nm. Incident light intensity current characteristics show linearity upto 45 mW ·cm-2, beyond which saturation in short circuit current is obtained. An efficiency ( η) of about 2% is obtained for these cells.
Making a Monolayer Hole in a Graphite Surface by Means of a Scanning Tunneling Microscope
Authors: Mizutani Wataru , Inukai Junji , Ono Masatoshi
Published: February 2005

It is reported that small pits are made in a graphite surface by applying voltage pulses using a scanning tunneling microscope (STM). A shallow hole, whose diameter was about 10 nm, was formed by creating the pits along the circumference of a circle. The depth of the hole was about 0.35 nm, which is very close to the interlayer distance of graphite. The result indicates the possibility of cutting a piece of layered material by monolayer thickness using an STM. The chemical process of pit formation is discussed.
Probing Absorption of Deuterium into Palladium Cathodes During D2O Electrolysis with an In Situ Electrochemical Microbalance Technique
Authors: Oyama Noboru , Yamamoto Nobushige , Hatozaki Osamu , Ohsaka Takeo
Published: February 2005

The in situ observation of the absorption of deuterium (or hydrogen) into the Pd cathode during D2O (or H2O) electrolysis was made by an electrochemical microbalance technique which is based on the quartz-crystal electrode. The resonant frequency of the Pd-coated quartz-crystal electrode decreased with increasing amount of charge passed during electrolysis, and the frequency change for the D2O electrolysis was about twice that for the H2O electrolysis. The atom ratios of H/Pd and D/Pd of the H-Pd and D-Pd compounds resulting from the electrolysis were estimated to be 0.59 and 0.57, respectively.
Reduction of Dislocation Density in Impurity-Doped GaAs Grown on Si Substrate by Molecular Beam Epitaxy
Authors: Lee Jong-Lam , Kobayashi Hidetoshi , Tanigawa Shoichiro , Kawabe Mitsuo
Published: February 2005

The addition of impurities such as Be and Si during the epitaxial growth of GaAs on Si substrate by molecular beam epitaxy caused the reduction of dislocation density. This was demonstrated by the depth distribution of vacancy-type defects obtained from slow positron measurements and by etch pit observation. The slow positron beam results indicate that impurities, Si and Be, increase concentrations of Ga vacancies and interstitials in the grown GaAs, respectively. The results suggest that these defects assist the enhanced dislocation climb, resulting in the reduction of dislocation density in impurity-doped GaAs.
Effects of Sb or Sn Addition on Precipitation of the High-Tc Superconducting Phase from Rapidly Quenched Bi-Pb-Ca-Sr-Cu-O Glasses
Authors: Tsuboi Shinzo , Tohge Noboru , Tatsumisago Masahiro , Minami Tsutomu
Published: February 2005

High-T
c superconductors were prepared from rapidly quenched Bi1.6Pb0.4M0.1Ca2Sr2Cu3O
x
(M=Sb or Sn) glasses. It was found that the addition of Sb or Sn gave the different effects on the precipitation of the 110 K phase from the glasses. The Sb added samples, the crystallized phases of which were mainly composed of the 110 K phase, showed the T
c value of 103 K and the J
c value of 300 A/cm2 (at 77 K). On the other hand, Sn added samples exhibited both higher T
c (110 K) and J
c (3000 A/cm2 at 77 K) in spite of the smaller volume fraction of the 110 K phase.
Superlattice Structure of TlBa2Ca2Cu3Oy and Tl2Ba2Ca2Cu3Oy (c/2)
Authors: Kawashima Syunichiro , Inoue Osamu , Adachi Seiji
Published: February 2005

A new phase, Tl1.5Ba2Ca2Cu3O
y
, with a superlattice structure of 1223 and 2223 (c/2) has been synthesized. The presence of this phase was confirmed by powder X-ray diffraction (XRD) and transmission electron microscope (TEM).
Irradiation Damage Caused by Ion Milling in Bismuth-Based Superconductors
Authors: Wu Xiao-Jing , Shoda Kaoru , Horiuchi Shigeo
Published: February 2005

Thin specimens for transmission electron microscopy were prepared by an ion-milling technique under different conditions from Bi2Sr2Ca
n-1Cu
n
O
x
superconductors with different phases (n=1, 2 and 3). They suffered ion irradiation damage so that a structural change from a crystalline to an amorphous state occurred locally. The damage rate depends on the species of phase, the crystal orientations and the milling conditions. It is slightly suppressed when specimens are cooled down to about 77 K during thinning.
Crystalline Qualities and Critical Current Densities of As-Grown Ba2YCu3Ox Thin Films on Silicon with Buffer Layers
Authors: Myoren Hiroaki , Nishiyama Yukio , Miyamoto Naokazu , Kai Yasuaki , Yamanaka Yasushi , Osaka Yukio , Nishiyama Fumitaka
Published: February 2005

As-grown Ba2YCu3O
x
thin films (\lesssim100 nm) have been prepared by rf magnetron sputtering deposited on Si(100) with buffer layers of YSZ and Y2O3/YSZ. Epitaxial growth of Ba2YCu3O
x
thin films is confirmed by ion channeling measurements along the (100) directions of the Si substrate showing a χmin of 60% on YSZ/Si, and 6% on Y2O3/YSZ/Si using 2.0 MeV He+. The as-grown films have critical current densities of 104 A/cm2 on YSZ/Si and 106 A/cm2 on Y2O3/YSZ/Si at 77 K. Our results indicate that the superconducting properties of the films are limited primarily by the value of lattice mismatch between the Ba2YCu3O
x
and buffer layers.
Resonant Third-Harmonic Generation of ArF Laser in H2 and Kr Gas Jets at 64 nm
Authors: Hirakawa Yasuyuki , Okada Tatsuo , Maeda Mitsuo , Muraoka Katsunori
Published: February 2005

Two-photon resonant third-harmonic generation (THG) in H2 and Kr gas jets at 64 nm was investigated by using a tunable ArF excimer laser. It was found that the THG efficiency of H2 was more than one order of magnitude higher than that of Kr. This technique will be useful in extending the tunable XUV range down to 66 nm by four-wave mixing with a dye laser.
Monolithic Integration of Photodetector and ARROW-Type Interferometer for Detecting Phase Difference between Two Optical Paths
Authors: Sakamoto Tomoharu , Kokubun Yasuo
Published: February 2005

We fabricated an interferometer for detecting phase difference between two optical paths by the combination of a dual-core fiber and ARROW (antiresonant reflecting optical waveguide), which was integrated with a pair of photodetectors. An optical sensor was demonstrated by using this integrated interferometer.
New Mechanism of Exciton Recombination in GaP–Exciton Bound to Neutral Donor and Neutral Acceptor Pair–
Authors: Mochizuki Yasunori , Mizuta Masashi
Published: February 2005

A new luminescent band in Zn-doped GaP was studied by low temperature photoluminescence. The high energy tail of this band originates from the so-called C-line, which is due to the recombination of excitons bound to neutral donors. Furthermore, its intensity was found to be strongly correlated to the electrical activity of Zn-acceptor. These facts suggest the involvement of both donor and acceptor in the radiative recombination process. The luminescent properties of this band were found to be quite similar to those of the so-called undulation spectra which is due to the recombination of exciton bound to isoelectronic impurity-neutral acceptor (N-Zn) pair. In this context, we propose that this band is due to a new mechanism of exciton recombination: exciton bound to neutral donor and neutral acceptor pairs.
Ferroelectric Liquid Crystals Incorporating the Optically Active γ-Lactone Ring
Authors: Koden Mitsuhiro , Kuratate Tomoaki , Funada Fumiaki , Awane Katsunobu , Sakaguchi Kazuhiko , Shiomi Yutaka , Kitamura Tohru
Published: February 2005

Ferroelectric liquid crystals incorporating an optically active γ-lactone ring were prepared. They show enantiotropic smectic C phases which have very large spontaneous polarizations as large as ∼590 nC/cm2 (5.9 mC/m2). The large spontaneous polarizations are attributed to the structural features wherein a dipole and two chiral centers are fixed in the γ-lactone ring.
Dielectric and X-Ray Diffraction Studies in Highly Ordered Complex Perovskite Pb(Yb1/2Nb1/2)O3
Authors: Kwon Jeong Rock , Choo C. K. K. , Woong Kil Choo Woong Kil Choo
Published: February 2005

Dielectric and X-ray diffraction measurements were used to characterize the structural phase transition occurring in antiferroelectric Pb(Yb1/2Nb1/2)O3 compound. Dielectric behavior for ceramics shows a sharp transition with a large temperature hysteresis of about 6°C near transition temperature. The lattice parameters and spontaneous strain have been investigated in the temperature range between 20 and 400°C using X-ray powder diffraction. High temperature X-ray data indicates that the Pb(Yb1/2Nb1/2)O3 undergoes an orthorhombic to cubic phase transition near transition temperature. The temperature dependence of the spontaneous strain is discussed by phenomenological theory.
Application of Pulse-Heating Method to Electroless Ni Alloy as a Thin-Film Resistor
Authors: Kawaguchi Jun , Osaka Tetsuya , Saito Iku , Yamazaki Takuya
Published: February 2005

The effect of heat treatment on electroless ternary NiMoB and NiWP, and binary NiB alloy films was investigated using a pulse-heating method that provides a very high heating rate (up to 106K min-1) and a very short heating time (200-1000 ms). The electroless ternary alloy system gives quite different behavior when using the pulse or conventional long-term heat treatment. Namely, ternary alloys in the form of film become close to pure Ni, rather than a NiMo or NiW solid solution when being pulse-heated, while no such a behavior is observed with the conventional heat treatment. For the binary electroless NiB alloy film, the behavior is similar to that in the NiP alloy system already reported. However, with faster heating rates the NiB alloy tends to behave similarly to the ternary alloys.
Deformation of Vesicles under the Influence of Strong Electric Fields
Authors: Hyuga Hiroyuki , Jr. Kazuhiko Kinosita, , Nobuyoshi Wakabayashi Nobuyoshi Wakabayashi
Published: February 2005

The deformation of vesicles with conducting membranes in external electric fields has been studied in the framework of the perturbation theory. A simple model for dynamics of deformation is proposed, and the results of numerical calculations for typical combinations of the vesicle size and the electric field are presented. When the conductivity inside a spherical vesicle is larger than that of the exterior medium, the deformations, both static and dynamic, are prolate and, otherwise, they are oblate.
Optical Transitions via the Structure-Defect Levels Due to Lattice Vacancies in InSb
Authors: Chen Jun-Yuan , Jenn-Gee Lo Jenn-Gee Lo , Luke Su Lu Luke Su Lu
Published: February 2005

A detailed theoretical analysis of optical transitions via deep levels due to lattice defects is worked out with application to the indium vacancy V
In in InSb. The originality of the proposed method is to extract useful parameters of defect which can not be obtained directly from experiments. Applying the theoretical model in which the optical line-shape function is represented by a Gaussian form with two adjustable parameters, we can extract some useful physical quantities characterizing the deep-defect centers, such as the phonon-coupling strength in the optical transitions, from the infrared optical absorption spectra. The application of theoretic model to the case of InSb:V
In tells us a weak phonon-coupling strength (about 0.01 eV at most) is involved in the optical transition, as predicted from the Lucovsky model.
Chemical Etching Characteristics of (100)GaAs in Kusatsu Spa Water
Authors: Sadao Adachi Sadao Adachi
Published: February 2005

We have successfully demonstrated that a solution of Kusatsu Spa water (KSW)/H2O2 etches (100)GaAs wafers. This etchant system provides high-quality etched surfaces without any undesirable roughness or etch pits. The etching rate was found to be easily controlled by changing the etchant component proportions. The etchant system has reproducible etching rates and does not erode photoresist masks.
Microwave Generation using a SNS Junction
Authors: Adir M. Luiz Adir M. Luiz , Roberto Nicolsky Roberto Nicolsky
Published: February 2005

It has been shown recently that the current-voltage characteristic of a metallic (non-tunneling) Josephson junction could exhibit a negative differential resistance at low voltages, as a predictable and reproducible effect. This letter shows an alternative procedure to generate non-Josephson microwaves (in the cm and mm range) taking advantage of this effect. It is shown that, instead of obtaining harmonic oscillations with the AC Josephson effect, it is possible to generate microwaves using the averaged IVC (current-voltage characteristics) of a SNS junction (a Josephson junction which exhibits no tunneling and has no hysteresis in the IVC).
A New Operation Mode of a Ferroelectric Liquid Crystal Cell with an Asymmetrical Surface Condition II
Authors: Kondo Katsumi , Yoneya Makoto , Sudo Yuka , Motomi Odamura Motomi Odamura , Teruo Kitamura Teruo Kitamura
Published: February 2005

A new operation mode which has two substrates with different surface interaction characteristics, a ferroelectric liquid crystal mixture with a large spontaneous polarization, a large tilt angle, and an N*·Sc* transition, is experimentally studied. Measuring optical properties of the developed cell shows that the new operation mode provides black and white images even when the cell is thick (3-6 µm).
Deposition of Hydrogenated Amorphous Silicon Films Using a Microwave Plasma Chemical Vapor Deposition Method with DC Bias
Authors: Kiyotaka Kato Kiyotaka Kato , Isamu Kato Isamu Kato
Published: February 2005

A DC bias is applied to a substrate placed in spatial afterglow plasma created by the double-tubed coaxial line-type microwave plasma chemical vapor deposition system. This DC bias method enables us to control only the ion bombardment energy without changing the ion flux density and the radical density. Hydrogenated amorphous silicon films were deposited, varying only the ion bombardment energy. With increasing ion bombardment energy, the dihydride bonds Si-H2 and the polyhydride bonds (Si-H2)n decrease, and the monohydride bonds Si-H and the film density increase.
The Enhanced Penetration of Oxygen along the Grain Boundary in Semiconducting Barium Titanate
Authors: Hasegawa Akira , Fujitsu Satoru , Yanagida Kunihito Koumoto
Published: February 2005

The characteristics of Positive Temperature Coefficient of Resistivity (PTCR) thermistors depend strongly on the atmosphere, especially oxygen, during the fabrication process. The PTCR jump decreases when the sample is heated in a reducing atmosphere, while it increases when the sample is heated in air. The behavior of oxygen which is important to improve the PTCR jump has been examined by a tracer (18O) method. The depth profile of the tracer has been determined by means of Secondary ion mass spectrometry (SIMS). The rate of penetration of oxygen into the grain boundary is very rapid and the PTCR jump depends on the amount of the oxygen penetrated into such a region.
Study of the Dynamic Behavior of Stearic Acid Monolayers at the Air-Water Interface in the Range of Low Surface Pressures by a Current-Measuring Technique
Authors: Majima Yutaka , Akitoshi Watanabe Akitoshi Watanabe , Mitsumasa Iwamoto Mitsumasa Iwamoto
Published: February 2005

We have studied the dynamic behavior of stearic acid monolayers on the surfaces of pure water and of salt solutions in the range of immeasurably low surface pressures during the course of monolayer compression, by using a current-measuring technique. For monolayers formed on the surfaces of pure water and of deionized water containing cadmium ions, displacement current was generated when the area per molecule was smaller than about 60 Å2, whereas the current was negligibly small in the range of area per molecule greater than about 60 Å2. For monolayers formed on the surface of distilled water containing aluminum ions, displacement current was generated in the entire range during the course of monolayer compression. Finally, the mechanism on the current generation observed in the present current measurement was theoretically analyzed.
Fundamental Theory for Ion Contributions to Radio Frequency Discharges between Planar Electrodes
Authors: Shigehiko Nonaka Shigehiko Nonaka
Published: February 2005

Ion contributions in planar radio frequency (RF) discharges were disclosed by solving a quasi-static linear Laplace equation self-consistently in the stationary state. Negative ions were also taken into consideration. As the results, the produced plasma density, threshold for an applied RF voltage and the electric field in plasma to maintain the discharges were obtained definitely. The present theory may be applicable for wide ranges of gas pressures and RF frequencies.
Nascent Rovibrational Distributions of CO(d3Δi, a′3Σ+) Produced by Excitation-Transfer Reactions from Xe(3P2) to 12CO and 13CO at Thermal Energy
Authors: Tsuji Masaharu , Yamaguchi Kazuo , Hiroyuki Kouno Hiroyuki Kouno , Yukio Nishimura Yukio Nishimura
Published: February 2005

The excitation-transfer reactions from Xe(3P2) to 12CO and 13CO at 39 meVcm have been studied using a beam apparatus. The near-resonant endoergic d
3Δ
i
(v
′=6, 7) and a
′3Σ+(v
′=11) levels of CO were selectively excited for both isotopes. The nascent rovibrational distributions of CO(d, a
′) were determined from a spectral simulation. The rotational distributions were expressed by Boltzmann temperatures of 300-650 K for all levels. The low rotational excitation was explained by the fact that curve crossings between the entrance and exit potentials occur in the attractive region of the exit potentials. The spin-orbit state selectivity was estimated for the population of the 12CO(d
3Δ1,2,3:v
′=6) sublevels.
Performance of the Charge-Coupled Device for Direct X-ray Detection in the Energy Range of 1-9 keV at the Synchrotron Radiation Facility
Authors: Tsunemi Hiroshi , Shin'ichi Kawai Shin'ichi Kawai , Kiyoshi Hayashida Kiyoshi Hayashida
Published: February 2005

We performed a calibration of the charge-coupled device (CCD) in the direct X-ray detection method. The CCD chip is a product for optical use. The X-rays which we used are from the BL-7A in the Ultraviolet Synchrotron Orbit Radiation (UVSOR) facility, which gives us X-rays in the energy range between 1 and 9 keV. We report here the various characteristics of the CCD and its validity as an X-ray imager with a spatial resolution of pixel size (12×12 µm2) as well as an X-ray spectrometer at an energy resolution of about 240 eV (full width at half-maximum; FWHM) at the 5.9 keV X-ray. Our system functioned properly at a standard flux level in the UVSOR facility.
Effects of Current Stress on the Characteristics of a Si Heterojunction Bipolar Transistor with a Hydrogenated Microcrystalline Si Emitter
Authors: Katsumi Murase Katsumi Murase , Mamoru Kuwagaki Mamoru Kuwagaki
Published: February 2005

Changes in the characteristics of a µc-Si:H-emitter Si-HBT induced by forward current stress imposed on the emitter-base junction are studied. The principal changes appear in the base current which consists of the diffusion and the band-gap-state-assisted tunneling currents. The diffusion current at first increases and later decreases as stressing proceeds; the overall result due to long-term stressing is reduction. Consequently, the maximum h
FE, governed by the diffusion current component, is enhanced as a result of stressing. The tunneling current increases monotonically with increasing stress time, resulting in degradation of h
FE at low output currents. Changes in both diffusion and tunneling currents can be explained by the simultaneous occurrence in µc-Si:H of increases in the active dopant and the defect densities.
Dependence of In-Plane Anisotropy in Polyimide Langmuir-Blodgett Films on Molecular Weight of Polyamic Acid
Authors: Sorita Tetsuji , Miyake Shiro , Hirofumi Fujioka Hirofumi Fujioka , Hiroyuki Nakajima Hiroyuki Nakajima
Published: February 2005

The relation between molecular weight of polyamic acid and inplane anisotropy in the LB films was investigated. As the molecular weight increases, orientation order of the polymer chains to the dipping direction in the LB films and that of the liquid crystal on the LB films become uniform. The orientation of liquid crystal is seemed to reflect that of the polymer chains. The experimental results can be qualitatively explained by the flow orientation model. It is assumed that origin for orientation of the polymer chains is attributed to the flow in vicinity of a substrate during dipping. The spreading solution stored for over a week results in inferior quality LB film as an alignment layer. Refering to the molecular weight dependence, it is thought that the degradation of the solution is caused by lowering of the molecular weight of polyamic acid due to hydrolysis.
Thermal Analysis of a New High Density Package Cooling Technology Using Low Melting Point Alloys
Authors: Ishizuka Yoshitaka Fukuoka
Published: February 2005

This paper describes one of the new package cooling technology concepts using a phase changing material (PCM) which would help develop high density packaging. A low cost alloy, composed of Bi/Pb/Sn/In whose melting point is 57°C, was used as the PCM.
Thermal experiments using the abovementioned alloy had been studied by the authors.1) It was confirmed that the substrate back surface temperature could be fixed at the PCM's melting temperature for several minutes by thermal absorption, while the PCM phase changed from its original solid state into the liquid state. Also, in the present work, it has been confirmed that thermal network method is practically useful using a personal computer for the thermal design of a package with a PCM.
Analysis of Real-Time Monitoring Using Interference Effects
Authors: Shuji Nakamura Shuji Nakamura
Published: February 2005

The interference effect, which is measured as a temperature oscillation by a narrow optical band-pass pyrometer during GaN growth in metalorganic chemical vapor deposition (MOCVD), was analyzed by calculating the transmittance and the reflectance. The results of the calculations showed that the attenuation of the oscillation amplitude with increasing thickness was not caused by the absorption of the growing layer. To explain this attenuation, the thickness fluctuation within the measured area was proposed. The thickness fluctuation and the growth rate of the growing layer are reflected on the trace of transmittance using the present real-time monitoring technique, which observes the interference effect.
Novel Pressure Sensors Using Epitaxially Stacked Si/Al2O3/Si Structures for High-Precision Thickness Control of Silicon Diaphragms
Authors: Chung Gwiy-Sang , Kawahito Shoji , Ishida Makoto , Suzaki Tetsuo , Tetsuro Nakamura Tetsuro Nakamura
Published: February 2005

Using epitaxial Al2O3 films as an etch-stop layer, Si-on-insulator (SOI) pressure sensors have been fabricated on a heteroepitaxially grown Si(100)/Al2O3(100)/Si(100) substrate. The epitaxially stacked SOI structure was formed by successive chemical vapor deposition of Al2O3 and Si on a 2-inch Si(100) substrate. The implemented sensors have a high sensitivity of 0.28 mV/V·kPa for a 93.3 kPa full-scale pressure range, with a nonlinearity and hysteresis of less than +0.2%FS and +0.09%FS, respectively. The pressure sensitivity variation can be controlled to within a standard deviation of ±2.0%. The shifts in sensitivity and offset voltage of the fabricated pressure sensors are less than -0.36% and +0.22%, respectively, in the temperature ranges of from -20°C to +100°C. The epitaxially stacked SOI structure is a highly promising material for the development of high-resolution pressure sensors with no-variation pressure sensitivity.
Preparation of YBa2Cu3O7-x (YBCO) Superconductive Film Using Sol-Gel Method
Authors: Masuda Yoshio , Tateishi Tsuyoshi , Matsubara Kazuo , Rikuro Ogawa Rikuro Ogawa , Yoshio Kawate Yoshio Kawate
Published: February 2005

Using alkoxides of Y and Ba and Cu-acetate as raw materials, Y Ba2Cu3O7-x
(YBCO) superconductive films were produced through the sol-gel method. When the nonaqueous mixed solution was hydrolyzed under an appropriate condition, a pure and homogeneous YBCO powder could be prepared. Controlling the metal concentration and the temperature of the sol, precursor(gel) films were formed on YSZ substrate by dip-coating. And heating the films in the range of 200°-950°C, changes of the films morphologies, the generated phases and the film reactions with the substrates were studied using scanning electron microscopy and X-ray diffraction. It has been known that to improve the superconductivity of the film it is necessary to sinter it at as high as 950°C and increase its thickness over about 3 µm after sintering. A superconductive film with T
c.off=75 K was obtained by adopting these conditions.
Rapid Synthesis of the YBa2Cu3Ox Film on Metal Substrate by Chemical Vapor Deposition Technique
Authors: Yamaguchi Taichi , Aoki Shin-ya , Sadakata Nobuyuki , Kohno Osamu , Saji Akira , Kuroda Noboru
Published: February 2005

A new chemical vapor deposition technique has been developed for rapid (max. 24 µm/h) formation of the oxide superconductor film on a metal substrate. In this system, blended β-diketonate chelates of source materials were slowly fed to the vaporizer with carrier gas. The source gas from the vaporizer and O2 gas were introduced into the reactor. We realized a superconducting YBCO thin film that had a T
c=87 K on a Hastelloy C-276 substrate.
Operating Characteristics of Optically Addressed Spatial Light Modulators Incorporating Distorted Helix Ferroelectric Liquid Crystals
Authors: Landreth Bruce , Chong-Chang Mao Chong-Chang Mao , Garret Moddel Garret Moddel
Published: February 2005

Distorted helix ferroelectric liquid crystals have received attention recently due to the availability of short-pitch, high-spontaneous-polarization mixtures. In this paper we discuss the operating characteristics of an optically addressed spatial light modulator incorporating a hydrogenated amorphous silicon photosensor and a distorted-helix ferroelectric liquid crystal light modulator. The device exhibits a grey-scale response over a range of write-light intensities which depends on operating frequency. The spatial resolution is 30 lp/mm. The time-averaged contrast ratio is 7:1, limited primarily by non-uniformity in the liquid crystal alignment. During switching, both the average optic axis orientation and the effective birefringence of the liquid crystal change. The capability of the device to produce a pseudocolored readout image is attributed to the latter effect.
Resonance Curves Obtained in the Vibration of Fe-3%Si Reeds
Authors: Yoshimura Masamichi , Akiyama Tomoko , Shigekawa Hidemi , Tsuno Takao , Nakamura Yoshio , Shin-ichi Hyodo Shin-ichi Hyodo
Published: February 2005

A series of amplitude-vs-driving-frequency measurements were performed for the forced vibration of Fe-3%Si reeds. With an increase in the magnitude of the driving force, the resonance frequency tended to shift to the lower side, similarly to soft-spring-type resonance. For sufficiently large driving force, however, it was found that the resonance curve became skewed and the resonance frequency began to shift to the higher side, similarly to hard-spring-type resonance.
Measurements of Ion Angular Velocity of Field Reversed Configuration with Suppressed Rotational Instability
Authors: Ito Yoshifumi , Arai Noriyuki , Ueda Yoshio , Sugimoto Satoshi , Okada Shigefumi , Seiichi Goto Seiichi Goto , Tsutomu Ishimura Tsutomu Ishimura
Published: February 2005

The angular velocity Ωc of the impurity ions (CV) is measured spectroscopically for the FRC (Field-Reversed-Configuration) plasmas confined in the θ-pinch region and translated into the confinement region with magnetic mirror field. The FRC plasma confined in the θ-pinch region becomes unstable due to the n=2 rotational instability which can be suppressed by the multipole magnetic field. The ion rotation in the stabilized plasma is almost equal to the velocity in the unstabilized case, suggesting that the multipole field acts on the plasma surface due to the skin effect and suppresses the instability without changing the field configuration within the separatrix radius. The FRC plasma translated in the confinement region is stable without destructive instability. The ion rotation in such a plasma indicates that a suppression mechanism of the n=2 instability exists, which is excited by the rotation in the confinement region.
Observation of m=0 Structure with Streak Picture in a Reversed Field Pinch Having Large Magnetic Reynolds Number
Authors: Arimoto Hideki , Masamune Sadao , Nagata Akiyoshi , Nakamura Akira , Matsuoka Akio , Tsukisima Takashige , Koichi Sato Koichi Sato
Published: February 2005

The technique of streak pictures with an image converter camera (IMACON) has been applied to the STP-3(M) reversed field pinch (RFP) experiments. A pattern of stripes in the streak pictures has been observed. This pattern is typical that of plasma with large magnetic Reynolds number S (S≥500). Each stripe has the m=0, low n structure, where m and n are the poloidal and toroidal mode numbers, respectively, which correlates with m=0 magnetic fluctuations. The origin of this m=0 structure is ascribed to nonlinear interaction of the m=1 modes which play essential roles in the RFP dynamo. It is thus demonstrated that the streak pictures are an efficient means of understanding the nonlinear mode coupling in RFP plasma. Further applications of the IMACON to the RFP experiments are also discussed.
Output Characteristics in an C2H5OH-N2 Gas Mixture of a Gas Polarographic Oxygen Sensor Using a Zirconia Electrolyte
Authors: Usui Toshio , Asada Akiyoshi , Kohsei Ishibashi Kohsei Ishibashi , Mitsuhiro Nakazawa Mitsuhiro Nakazawa
Published: February 2005

Output characteristics in an C2H5OH-N2 gas mixture of a gas polarographic oxygen sensor using a zirconia electrolyte have been investigated at 450°C. The limiting current was realized in the C2H5OH-N2 gas mixture, similar to that in H2-N2 gas mixtures. This limiting current in the C2H5OH-N2 gas mixture was caused by the fact that gaseous diffusion of ethanol through the gas diffusion hole of the sensor was a rate-determining step.
Junction Location Measured by Spreading Resistance Probe
Authors: E. C. André E. C. André
Published: February 2005

Spreading resistance measurements are known to be the only means for profiling the whole range of silicon concentrations. But it is also known that under certain conditions of profiles and concentrations the results are somewhat questionable. In a bipolar structure for instance, both the thickness and the doping level of the base might be much lower than the actual values. A method based on experimental data has been devised and algorithms implemented to bring these values to the right ones. Moreover it must be emphasized that the sensitivity limit of Spreading Resistance Probe (SRP) has also been experimentally demonstrated. In a silicon material of doping level C
su any foreign impurity concentration C
im can be measured as long as C
im>0.01 C
su.
Mechanisms of High PSG/SiO2 Selective Etching in a Highly Polymerized Fluorocarbon Plasma
Authors: Ikegami Naokatsu , Ozawa Nobuo , Yasuhiro Miyakawa Yasuhiro Miyakawa , Jun Kanamori Jun Kanamori
Published: February 2005

We have investigated high selective etching mechanisms of phosphosilicate glass (PSG) over SiO2 in a highly polymerized fluorocarbon plasma, by studying the Ar+ induced reactions between the adsorption layer and the underlying substrates with X-ray photoelectron spectroscopy. Both of SiO2 and PSG were found to react in a very near surface region, chiefly with the adsorption layer, by reflecting the reactivity in SiO
x
F
y
reaction layer below the surface. The mechanisms of the reactivity variance were explained by the difference in density of active sites for unsaturated CF
x
chemisorption induced by ion bombardment, and the difference of Si-O bond breakability of the underlying substrates. These effects are caused by the existence of P-O or P=O bonds in PSG.
After-Corrosion Suppression Using Low-Temperature Al-Si-Cu Etching
Authors: Aoki Hidemitsu , Ikawa Eiji , Kikkawa Takamaro , Teraoka Yuden , Nishiyama Iwao
Published: February 2005

The authors investigated the low-temperature etching effect on Al-Si-Cu after-corrosion. The after-corrosion extent was evaluated from the corrosion point density generated on the rinsed Al-Si-Cu stripes after dry etching. As the etching temperature was reduced, after-corrosion was suppressed. In order to study the low-temperature etching effect, the authors analyzed the Cl compounds remaining on the Al-Si-Cu film by thermal desorption spectroscopy (TDS). TDS revealed that the Cl concentration remaining on the Al-Si-Cu film etched at -60°C after rinsing in water was smaller than that remaining on the film etched at 30°C. Consequently, suppression of after-corrosion by low temperature etching could be attributed to the smaller number of Al-Cu bonds remaining in the Al-Si-Cu etch surface after removal of the AlCl
x
layer by rinsing with water. This fact is due to the reduction of chemical reaction and diffusion rate by lowering the substrate temperature.
Mechanism of Corrosion in Al-Si-Cu
Authors: Hayasaka Nobuo , Koga Yuri , Shimomura Koji , Yoshida Yukimasa , Haruo Okano Haruo Okano
Published: February 2005

An Al-Cu local cell was formed between the Cu precipitation and adjacent Al in an Al-Si-Cu alloy when Cu was added in excess to the alloy. Once an Al-Cu local cell was formed, corrosion took place simply by dipping the alloy in deionized water without any contamination. Furthermore, it was found that corrosion was enhanced at the Al-Si-Cu lines in contact with the p+-n junction of Si. The reason for this is that holes are injected into Al-Si-Cu from p+-Si due to electromotive force produced by light irradiation and an external circuit connecting the alloy and n-Si formed by the adsorption of moisture on the surface. Furthermore, it was found that the irradiation of light with a wavelength between 320 to 380 nm was most effective in enhancing the corrosion reaction.
Cathodoluminescence Properties of Undoped and Zn-Doped AlxGa1-xN Grown by Metalorganic Vapor Phase Epitaxy
Authors: Itoh Kenji , Amano Hiroshi , Kazumasa Hiramatsu Kazumasa Hiramatsu , Isamu Akasaki Isamu Akasaki
Published: February 2005

Cathodoluminescence of undoped and Zn-doped Al
x
Ga1-x
N epitaxial layers grown by Metalorganic Vapor Phase Epitaxy (MOVPE) in the composition range of 0≤x≤0.3 has been studied at room temperature. The dominant emission of undoped Al
x
Ga1-x
N grown at 1030°C is a near-band-edge emission (UV band), while that of Zn-doped Al
x
Ga1-x
N grown at 1030°C is a violet-blue one (VB band), and that of Zn-doped Al
x
Ga1-x
N grown at 910°C is a blue-green one (BG band). Each emission band shifts toward a higher-energy side with increasing x. The compositional dependence of the peak energy of the UV band is similar to that of the band gap energy. On the other hand, the compositional dependences of the VB band and BG band are somewhat smaller than that of the band gap energy.
Molecular Beam Epitaxially Grown ZnSe(001) Surface Studied by the In Situ Observation of RHEED Intensity
Authors: Ohishi Masakazu , Saito Hiroshi , Torihara Hiroshi , Yasunori Fujisaki Yasunori Fujisaki , Kenzo Ohmori Kenzo Ohmori
Published: February 2005

The desorption of Zn and Se atoms or molecules on the (001) surface of a ZnSe/GaAs epitaxial layer were studied by means of reflection high-energy electron diffraction (RHEED). The temporal behavior of the specular intensity observed from two azimuths, [110] and [1̄10], was well understood by taking the surface condition into consideration; i.e., the surface terrace is elongated toward the [1̄10] direction and excessively adsorbed Se molecules exsist as well. We also confirmed that a higher-energy electron beam enhances the desorption of Se molecules and adatoms.
On the Properties of ZnSe/(NH4)2Sx-Pretreated GaAs Heterointerfaces
Authors: Ohnakado Takahiro , Wu Yi-hong , Kawakami Yoichi , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: February 2005

(NH4)2S
x
pretreatment of a GaAs surface successfully resulted in high-quality ZnSe/GaAs heterointerfaces, which are attractive for applications to heterojunction devices as well as metal-insulator-semiconductor field-effect transistors (MISFETs). In order to overcome the problem of small conduction band offset, which is undesirable for MIS structures, we propose a slight addition of Mg and S to ZnSe, i.e., the ZnMgSSe/GaAs heterointerface.
Thermodynamic Estimation of Oxidation Ability of Various Gases Used for the Preparation of Superconducting Films at High Vacuum
Authors: Hashimoto Takuya , Kishio Hideomi Koinuma
Published: February 2005

The oxidation ability of O2, O3, atomic oxygen, NO, N2O, and NO2 was estimated by thermodynamic calculation. The calculation was carried out on the equilibrium state of Cu2O/CuO, considering the temperature dependence of Gibbs free energy of formation. Gases such as NO2, O3, and atomic oxygen were proven to have oxidation abilities higher than that of O2, showing good agreement with the results of oxide film formation by molecular beam epitaxy.
Crystal Structure and Soft Magnetic Properties of FeZrN/AlN Multilayer Films
Authors: Taneko Noriaki , Shimada Yutaka , Fukamichi Kazuaki , Akira Yoshihara Akira Yoshihara , Chyoji Miyakawa Chyoji Miyakawa
Published: February 2005

Soft magnetic properties of Fe-Zr-N fine-grained films multilayered with AlN films as spacers are investigated. AlN spacers with a thickness of 5∼500 Å are studied. The magnetic softness and its thermal stability are dependent on the multilayer structure. This is because AlN spacers accelerate crystal growth of αFe, although they can be very thin, and improve the magnetic softness.
Preparation of Polycrystalline Bismuth and Aluminum Substituted Yttrium-Iron Garnet Films by Repetitive Gel Coating on Glass Substrates
Authors: Matsumoto Koji , Yamamoto Shinji , Yamanobe Yasunori , Ueno Akifumi , Kazuhiro Yamaguchi Kazuhiro Yamaguchi , Toshitaka Fujii Toshitaka Fujii
Published: February 2005

Perpendicularly magnetized films of polycrystalline bismuth-and aluminum-substituted yttrium iron garnet were prepared by spin coating a gel on glass substrates. The coated gel was preannealed at temperatures ranging from 300°C to 700°C for 10 minutes and was successively annealed at 700°C for 4 hours in air to form garnet crystals. Thicker garnet films were obtained by repetitive spin coating and the heat treatments stated above. However, magnetic as well as magneto-optical properties of the films were different according to whether preannealing after each coating was done below or above 400°C. This is caused by the formation of carbon-enriched layers on the free surface of each coated gel layer. These interlayers are considered to occur by hydrocarbon decomposition of the solvent and are found to vanish through evacuation of hydrocarbon from the films by preannealing above 400°C.
Third-Order Nonlinear Optical Properties in Soluble Phthalocyanines with Tert-Butyl Substituents
Authors: Hosoda Masahiro , Wada Tatsuo , Yamada Akira , Anthony F. Garito Anthony F. Garito , Hiroyuki Sasabe Hiroyuki Sasabe
Published: February 2005

This paper reports on third-order nonlinear optical properties in various phthalocyanine compounds with tert-butyl peripheral substitution on each benzo ring at either the 2- or 3-position (tetra-tert-butyl-substituted isomer mixture). The third-order optical susceptibilities χ1111
(3)(-3ω; ω, ω, ω)'s for the tetrakis(tert-butyl)phthalocyanine (TBPc) compounds were determined by optical third-harmonic generation measurements of spin-coated films at a wavelength of 1.907 µm. In each case, the third-order hyperpolarizability of the molecularly doped films is constant over the concentration of the TBPc's in polymethylmethacrylate. The χ(3) values of the TBPc's are smaller than those of unsubstituted phthalocyanines. In particular, χ(3) of tetrakis(tert-butyl)vanadylphthalocyanine (TBVOPc) is one order of magnitude smaller than that of VOPc. The origin of the large difference in χ(3) values is discussed in terms of molecular packing.
Optical Anisotropies in Modified Polycarbonates
Authors: Shigematsu Kazuyoshi , Shirouzu Shigenori , Sakamoto Shuji , Shikuma Haruo , Sohshi Togawa Sohshi Togawa , Takashi Nakagawa Takashi Nakagawa
Published: February 2005

A new series of modified polycarbonates were prepared by the substitution of ortho hydrogen (for carbonate group) of main chain phenyl group by methyl, phenyl and cyclohexyl groups. The relationships between chemical structures and stress-optical coefficients in the glassy state (C
g), refractive index anisotropy of constructive units (RIAC) and molecular motions were investigated in these systems.
Generation of a Diffraction-Free Laser Beam Using a Specific Fresnel Zone Plate
Authors: Takehiko Hidaka Takehiko Hidaka
Published: February 2005

A diffraction-free, high-efficiency light beam has been generated using a specific Fresnel zone plate and a suitable convex lens. The principle and experimental results are given.
Electrical Properties of Black Phosphorus Single Crystals Prepared by the Bismuth-Flux Method
Authors: Baba Mamoru , Izumida Fukunori , Morita Akira , Koike Yoji , Fukase Tetsuro
Published: February 2005

Systematic measurement of the electrical transport phenomena of black phosphorus grown by the all-closed bismuth-flux method has been performed in the range from room temperature down to 0.5 K for the electrical resistivity and down to 1.5 K for the Hall effect and the magnetoresistance effect. These samples exhibited p-type conduction with two types of acceptors, of which activation energies were 26.1 meV and 11.8 meV, respectively. The effective concentrations of acceptors were typically 1.36×1015 cm-3 for the deeper level and 0.44×1015 cm-3 for the shallower level. The maximum of the Hall mobility was found to be 2×104 cm2/Vs around 20 K. A new observation of n-type conduction below about 7 K for some of these samples suggested the existence of a surface inversion layer as a channel of electron conduction.
Superlattice Formation and Phase Transition in Silver Selenide
Authors: Hidejiro Miki Hidejiro Miki
Published: February 2005

Silver selenide has been prepared by the melt growth method and coprecipitation method. The X-ray diffraction and differential thermal analysis have been investigated. The superlattice has been observed on the coprecipitation-grown silver selenide after heat treatment. It is very important from the stand point of obtaining a superlattice structure, that the heat treatment temperature be between 150°C and 300°C. A new phase transition of silver selenide due to the formation of a superlattice has been observed in the vicinity of 100°C. The Seebeck coefficient, resistivity and thermal conductivity have been measured as a function of temperature.
Scanning Tunneling Microscopic Study of Structures of Deposited Palladium on Graphite
Authors: Kojima Isao , Arun Kumar Srivastava* Arun Kumar Srivastava* , Masayasu Kurahashi Masayasu Kurahashi
Published: February 2005

Scanning tunneling microscope (STM) has been applied to investigate the nucleation of Pd deposited on HOPG (Highly oriented pyrolytic graphite). Pd deposited at 70°C exists as small clusters of 3-5 nm below the monolayer coverage. At 450°C deposition, some of them nucleate to crystallize and grow epitaxially along the [111] direction. The topmost layer of the (111) face of the exposed crystal showed a long periodic structure with a periodic distance of 2.6-2.7 nm.