bluuebunny/crossref_metadata_2025 huggingface dataset:
Warp of Czochralski Wafer with Back-Surface Polycrystalline Silicon Film
Authors: Miyairi Hiroo , Tsuchiya Shin , Hideo Yoshioka Hideo Yoshioka , Hisaaki Suga Hisaaki Suga
Published: February 2005

Warp of Czochralski (CZ) Si wafers with back-surface polycrystalline silicon (BPS) film was measured with elevation of ambient temperature to 620-680°C, using a film internal stress meter (ULVAC Corporation FIS-1000). For the first time, to the aurthors' knowledge, it was clarified that the wafers were warped because of film-induced stress occurring at the film deposition temperature. Film-induced stress is divided into temperature-dependent stress (thermal stress) and residual stress at room temperature. Thermal stress is quantified under the assumption that warp depends on the apparent linear thermal expansion coefficients of the BPS film. Residual stress was measured by means of the X-ray diffraction method.
Optical Characterization of GaSb-Based Ternary and Quaternary Alloys Grown by Liquid-Phase Epitaxy at Low Temperatures
Authors: Ichimura Masaya , Kato Ken-ichi , Uekita Hiroshi , Kitamura Noboru , Akira Usami Akira Usami , Takao Wada Takao Wada
Published: February 2005

GaSb and GaSb-based alloys are grown by liquid-phase epitaxy (LPE) and characterized by photoluminescence (PL) and Raman spectroscopies. Although the concentration of the dominant native defect decreases with decreasing growth temperature, the crystalline quality of GaSb grown at 270°C is very poor: near-band-edge emission is not observed in the PL measurement and a peak due to forbidden scattering strongly appears in the Raman spectrum. On the other hand, Al
x
Ga1-x
Sb and Ga1-x
In
x
Sb ternary alloys and Al
x
Ga1-x-y
In
y
Sb quaternary alloys grown at the same temperature exhibit much better crystal quality than the binary: the near-band-edge emission is clearly observed in the PL spectra and only the allowed mode is detected in the Raman measurement. Thus we can improve the quality of the low-temperature-LPE-grown layer through alloying.
Antimony Passivation of InP
Authors: Hajime Nobusawa Hajime Nobusawa , Hideaki Ikoma Hideaki Ikoma
Published: February 2005

Antimony passivation of InP was investigated. Sb was evaporated on a HCl-etched InP substrate and annealed at 300°C for 10 min. I-V characteristics of the Au/Sb/InP diode are substantially improved and the Schottky barrier height becomes higher as compared with the conventional Au/InP diode. The reverse current decreases by about two orders of magnitude upon Sb passivation. X-ray photoelectron spectroscopic (XPS) measurements show that the Sb oxide, Sb2O3, is formed near both the surface and the interface, i.e., the Sb2O3/Sb/Sb2O3 layered structure exists on the InP substrate. On the other hand, In2O3, the dominant component species of the native oxide of InP, is not observed in the Sb-passivated sample, which indicates that Sb passivation effectively removes that native oxide (In2O3) and suppresses reoxidation of the InP surface. Sb is considered to reduce In2O3 and is oxidized itself to become Sb2O3. This is a probable mechanism of Sb passivation. After the Sb-passivated substrate is washed in deionized water, the amount of Sb decreases and In2O3 is again observed. This is explained by the balance in the chemical reaction between In2O3 and Sb2O3 (the mass-action law). The low Schottky barrier height and the poor electrical characteristics are thus well correlated with the existence of the native oxide of InP, dominantly, In2O3.
Improvement of n-Type Poly-Si Film Properties by Solid Phase Crystallization Method
Authors: Matsuyama Takao , Tanaka Makoto , Tsuda Shinya , Shoichi Nakano Shoichi Nakano , Yukinori Kuwano Yukinori Kuwano
Published: February 2005

Polycrystalline silicon (poly-Si) thin films prepared by the solid phase crystallization (SPC) method were investigated for application as photovoltaic materials. To improve the properties of the poly-Si thin film, two methods were developed to control crystallization. One is the partial doping method, in which starting material of a-Si consists of a doped layer and an undoped layer. We have succeeded in controlling nuclei generation using partial doping, and high mobility of 196 cm2/V·s was obtained at a carrier concentration of 1×1018 cm-3. SPC temperature can also be decreased to 500°C. The other is adoption, for the first time, of a textured substrate which exerted effects on the enlargement of grain size in poly-Si thin films prepared by the SPC method. By combining the partial doping method with the textured substrate, an n-type poly-Si thin-film with the grain size of 6 µm was fabricated which showed the Hall mobility of 623 cm2/V·s (n: 3.0\times1015 cm-3). In a solar cell (thickness: 12 µm) applying this film, a conversion efficiency of 6.2% was obtained and a collection efficiency of 50% was achieved at a wavelength of 900 nm.
Numerical Investigation of Stripe Structures in Ferromagnetic Thin Films with Perpenedicular Anisotropy
Authors: Bharat B. Pant Bharat B. Pant , Kimihide Matsuyama Kimihide Matsuyama
Published: February 2005

Stripe structures in ferromagnetic thin films with perpendicular
anisotropy
and quality factor Q < 1 are numerically investigated using energy minimization. This formulation is applied to films with NiFe-type material parameters, high anisotropy (O(100) Oe) and thickness in the range of ∼ 1000 – 2500 Å. For a given thickness, these films undergo a transition from a uniform in-plane state to a stripe state characterized by periodic out-of-plane tilt of magnetization as the anisotropy is increased above a critical value. The critical anisotropy decreases with increasing thickness; this critical relationship is calculated and is found to agree well with previous analytic results. The ratio of the stripe-state wavelength to film thickness is 2 on the critical locus but decreases as either the anisotropy or the film thickness is increased. The stray field outside the film surface has an amplitude O(10) Oe and submicron period.
Refractive-Index Dispersion in Zn1-xCdxTe Ternary Alloys
Authors: Sadao Adachi Sadao Adachi , Toshifumi Kimura Toshifumi Kimura
Published: February 2005

Refractive-index dispersion in Zn1-x
Cd
x
Te ternary alloys has been measured at room temperature in the 1.1-2.5-eV photon-energy range using spectroscopic ellipsometry. The results are fitted to the first-order Sellmeier equation. The high-frequency dielectric constant, ε∞, is also found to be not strongly dependent on the alloy composition x.
Accelerated-Deposition Rate and High-Quality Film Copper Chemical Vapor Deposition Using a Water Vapor Addition to a Hydrogen and Cu(HFA)2 Reaction System
Authors: Nobuyoshi Awaya Nobuyoshi Awaya , Yoshinobu Arita Yoshinobu Arita
Published: February 2005

Accelerated-deposition-rate chemical vapor deposition (CVD) of copper is studied using hydrogen reduction of bis-hexafluoro acetylacetonate copper (Cu(HFA)2). An in-situ hydrated Cu(HFA)2 formation system using gaseous H2O addition to the hydrogen carrier gas increases the deposition rate to 90 nm/min. This is about ten times larger than that of the conventional reaction system. It also improves the surface morphology and the electrical resistivity of the deposited copper film. A high-aspect-ratio via filling by selective CVD and excellent step coverage by blanket CVD are successfully obtained with this technique.
Initial Growth Process of Epitaxial Diamond Thin Films on cBN Single Crystals
Authors: Satoshi Koizumi Satoshi Koizumi , Tadao Inuzuka Tadao Inuzuka
Published: February 2005

The initial growth process of diamond thin films formed by dc plasma chemical vapor deposition on cubic boron nitride (cBN) surfaces of {111}B, {111}N and {100} has been investigated by scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). On the {111}B surface, it is observed that the carbonaceous layer decorates the edge of the terrace, and the epitaxial islands of diamond grow in the decorated regions. Most of the islands grow laterally until their size exceeds about 100 nm across. On the other hand, on the {111}N surface, neither the formation of carbonaceous layer nor epitaxy of diamond has been observed. The difference in the manner of growth on these two surfaces is roughly explained when the strength relationships of the chemical bonds formed on the substrate surfaces are taken into account. On the {100} surface, the formation of a carbonaceous layer has also been observed, together with the formation of pyramidal diamond islands. The carbonaceous layer plays an important role in the epitaxial nucleation of diamond.
Lateral-Solid Phase Epitaxial Growth of Single-Crystal Al(110) Films over Striped SiO2 Patterns*
Authors: Kusuyama Koichi , Yasushi Nakajima Yasushi Nakajima , Yoshinori Murakami Yoshinori Murakami
Published: February 2005

Aluminum films deposited by the conventional DC magnetron sputtering method over striped SiO2 patterns were single-crystallized by the lateral-solid phase epitaxial (L-SPE) growth method. Single-crystal Al(110) films deposited on striped Si(100) patterns were used as seed areas. The crystal structure of the films was investigated utilizing transmission electron microscopy (TEM), electron diffraction, X-ray diffraction (XRD) and optical microscopy. The grain density along L-SPE grown aluminum lines is influenced by the epitaxial growth direction. The result suggests the existence of anisotropy in the grain boundary energy of L-SPE grown aluminum films.
Photochromic Rewritable Memory Media: A New Nondestructive Readout Method
Authors: Tatezono Fumio , Harada Toshio , Shimizu Yoshiaki , Ohara Meguru , Irie Masahiro
Published: February 2005

A new nondestructive readout method was proposed for photochromic rewritable memory media. When the medium has a thermal threshold in the writing process with a λ1 laser, reading using two lasers having emission lines at λ1 and λ2, which correspond to absorption bands of the two isomers, makes it possible to keep the signal intensity constant. Reading more than 106 times without destroying the memory was achieved by using photochromic diarylethene media.
Single-Grating Gamma Ray Imaging System
Authors: King Chien Chou
Published: February 2005

A time-varying, single-sinusoidal-grating coded aperture which is translated between the radiative source plane and the detector plane is discussed. To the detector, the aperture behaves as a variable frequency grating that scans the object over a two-dimensional frequency domain by changing its orientation and position. The summation filter back-projection algorithm has been used to reconstruct the image. The object letter “E” was reconstructed successfully. The tomographic imaging capabilities of this system are also discussed.
Noncontact, Electrode-free Capacitance/Voltage Measurement Based on General Theory of Metal-Oxide-Semiconductor (MOS) Structure
Authors: Sakai Takamasa , Kohno Motohiro , Hirae Sadao , Ikuyoshi Nakatani Ikuyoshi Nakatani , Tatsufumi Kusuda Tatsufumi Kusuda
Published: February 2005

In this paper, we discussed a novel approach to semiconductor surface inspection, which is analysis using the C-V curve measured in a noncontact method by the metal-air-semiconductor (MAIS) technique. A new gap sensing method using the so-called Goos-Haenchen effect was developed to achieve the noncontact C-V measurement. The MAIS technique exhibited comparable sensitivity and repeatability to those of conventional C-V measurement, and hence, good reproducibility and resolution for quantifying the electrically active impurity on the order of 1×109/cm2, which is better than most spectrometric techniques, such as secondary ion mass spectroscopy (SIMS), electron spectroscopy for chemical analysis (ESCA) and Auger electron spectrocopy (AES) which are time-consuming and destructive. This measurement without preparation of any electrical contact metal electrode suggested, for the first time, the possibility of measuring an intrinsic characteristic of the semiconductor surface, using the examples of a concrete examination.
Analysis of Bending Displacement of Lead Zirconate Titanate Thin Film Synthesized by Hydrothermal Method
Authors: Ohba Yoko , Miyauchi Masahiro , Takaaki Tsurumi Takaaki Tsurumi , Masaki Daimon Masaki Daimon
Published: February 2005

Lead zirconate titanate solid-solution (PZT) films with various thicknesses were synthesized on titanium substrates by repeated hydrothermal treatments. Young's modulus and the density of the PZT film were measured by the vibrating-reed technique and Archimedes' method, respectively, and they were lower than those of PZT ceramic. We fabricated bimorph-type bending actuators using those films and analyzed the displacement induced by the electric field. It was found that the piezoelectric constant and electromechanical coupling factor of the PZT film were comparable to those of the ceramic, and also that the displacement was caused by the piezoelectric effect. The actuators were bent by applied voltage without poling, because the polar axes in the as-deposited film were aligned in the direction from the film surface to the substrate.
Film Thickness Dependence of Dielectric Property and Crystal Structure of PbTiO3 Film Prepared on Pt/SiO2/Si Substrate by Metal Organic Chemical Vapor Deposition
Authors: Funakubo Hiroshi , Hioki Tsuyoshi , Otsu Masato , Kazuo Shinozaki Kazuo Shinozaki , Nobuyasu Mizutani Nobuyasu Mizutani
Published: February 2005

The crystal structure of PbTiO3 film, which was prepared on a Pt/SiO2/Si substrate by metal organic chemical vapor deposition, was investigated along with its dielectric properties. The relative dielectric constant increased with increasing film thickness. Crystal structure difference was observed below 0.3 µm of film thickness, as compared to that above 0.3 µm of thickness; i.e., the lattice constant ratio of the c-axis to a-axis, the intensity ratio of (00l) to (h00) reflections and the average crystallite size decreased, and the nonuniform stress increased with decrease in the film thickness. These crystal imperfections for below 0.3 µm thickness might be related to the existence of a low relative dielectric constant layer near the substrate.
Dielectric Constant and Leakage Current of Epitaxially Grown and Polycrystalline SrTiO3 Thin Films
Authors: Kazuhide Abe Kazuhide Abe , Shuichi Komatsu Shuichi Komatsu
Published: February 2005

The dielectric constant and leakage current were studied for SrTiO3 films thinner than 100 nm, focusing on the influence of the dielectric-electrode interface and the grain boundary. Experimentally, the thickness dependence of the dielectric constant and leakage current was investigated for both epitaxially grown films and polycrystalline films. The interface between the dielectric and electrode, as well as the grain boundary, has been found to cause the lowering of the dielectric constant. The grain boundary has been found to exert a notable effect in suppressing the leakage current.
Ultrasonic Rotary Motor Using Longitudinal and Bending Multimode Vibrator with Mode Coupling Caused by External Additional Asymmetry
Authors: Manabu Aoyagi Manabu Aoyagi , Yoshiro Tomikawa Yoshiro Tomikawa
Published: February 2005

The present paper deals with the ultrasonic rotary motor using a longitudinal and bending multimode vibrator constructed so that the mode coupling is caused by external additional asymmetry. It is well known that on a rectangular piezoelectric plate vibrator with its two corners cut diagonally or a parallelogram-shaped piezoelectric plate vibrator, the first longitudinal and second bending vibration modes are coupled under a certain dimensional condition. The motor mentioned above is to use this phenomenon; that is, a one-channel drive, reversible rotary motor can be achieved. From results of measurement and calculation of such a trial vibrator, it was found that there were two new resonance vibration modes in the neighborhood of degenerate resonance frequencies of original longitudinal and bending vibrations; hence, the directions of rotor revolution were different at both new modes when the mode-coupled vibrator was used to construct an ultrasonic rotary motor. The trial motor has proven that a simple ultrasonic motor could be easily constructed and it was suitable for light-load use because of its small contact area to the rotor.
Characteristics of Ultrasonic Motor Driven by Pulse Train in Trapezoid Form
Authors: Kusakabe Chiharu , Tomikawa Yoshiro , Takano Takehiro , Aoyagi Manabu
Published: February 2005

This paper deals with the transient response of an ultrasonic motor driven by a pulse train in the form of a trapezoid. The relationship between the shape of the pulse train and the starting characteristics of the motor was clarified by simulation and experiment. The transient response of the motor can be obtained through response analysis of an electrically equivalent circuit, considering the two resonance modes of the stator. It was proven that the modification of the driving pulse train is effective for preventing transient vibration and the growth of metallic noise.
Rotor Displacement of the Ultrasonic Motor Having an Angular Displacement Self-Correction Function
Authors: Chen Xiaoduo , Kusakabe Chiharu , Tomikawa Yoshiro , Takano Takehiro
Published: February 2005

This paper deals with the experimental investigation for confirmation of rotor displacement of the ultrasonic stepping motor having an angular displacement self-correction function. The experiment focused on the relationship between the rotor's vibration displacement and its staying position for the self-correction. The result proved that the rotor always stays at the position where the displacement is smallest by cutting a slit into the rotor. Moreover, it has also been found that the stable self-correction of rotor angular displacement depends upon both the rotor driving frequency and rotor clamping force.
Motion Characteristics Measurement of Rotating Object Using Surface Acoustic Wave Oscillator
Authors: Sugizaki Goro , Takenaka Tadashi , Toda Koichiro Sakata
Published: February 2005

The configuration and characteristics of a surface acoustic wave (SAW) delay line oscillator for use as an accelerometer using a ceramic plate are described. The static strain sensitivity of the delay line oscillator using a Pb(Zr·Ti)O3-based piezoelectric ceramic plate is measured. The SAW accelerometer is a strain-sensitive SAW delay line oscillator, in which the oscillation frequency varies with bending stress imparted to the ceramic plate by four loading pins on a brass block that is subjected to force. The accelerometer is mounted on a rotating disk and its oscillation frequency deviation is measured against the number of rotations and the radial acceleration of the disk. The strain sensitivity in the form of the change of oscillation frequency is satisfactory for accelerometer performance.
Preparation of Modified Lead Zinc Niobate Compound Thick Films by Rapid Quenching
Authors: Kang Sang-goo , Kim Hwan , Takahashi Koichiro , Yukino Ken , Masayuki Tsukioka Masayuki Tsukioka , Fuzio P. Okamura Fuzio P. Okamura
Published: February 2005

The solid solution compound films of (1-x)PZN-xBZN system were synthesized by rapid quenching using a twin-roller system. These films have a thickness range 30-200 µm. The average grain size of thick films is 20-30 µm and the density is almost full. The phase of as-quenched thick films was slightly different from that in the crystalline powders before melting, but it was recovered after heat treatment. The chemical compositions were the same after quenching. The dielectric constant of the composition of 0.88PZN-0.12BZN thick films was 8000 at room temperature at 1 kHz. This result suggests a possibility of application of thick films made by rapid quenching to industrial use as high-permittivity multilayer capacitors.
Growth of Various Amino-Acid-Doped Triglycine Sulfate Crystals and Their Ferroelectric Properties
Authors: Noriyuki Nakatani Noriyuki Nakatani
Published: February 2005

Single crystals of triglycine sulfate (TGS) were grown from solutions containing 10 mol% of L-α-alanine, DL-α-alanine, sarcosine, L-serine or L-valine. The crystal form, domain structure and internal bias field E
b of these crystals were investigated. The crystal form and macroscopic distribution of E
b in crystals doped with L-α-alanine and L-serine show polar symmetry 2, and those in crystals with DL-α-alanine and sarcosine show the centrosymmetric 2/m. The molecule of L-valine cannot be incorporated in TGS crystal.
Electrostrictive Properties of Pb(Mg1/3Nb2/3)O3-Based Relaxor Ferroelectric Ceramics
Authors: Takagi Harumi , Koichiro Sakata Koichiro Sakata , Tadashi Takenaka Tadashi Takenaka
Published: February 2005

Perovskite-type Pb(Mg1/3Nb2/3)O3 (PMN)-based ceramics were prepared by modifying La(Mg2/3Nb1/3)O3 and PbTiO3. Dielectric and electrostrictive properties of modified PMN-based ceramics were investigated from the viewpoint of actuator materials. The temperature dependence of the dielectric constant, εs, shows a broader peak compared with that of pure PMN in the vicinity of room temperature. Transverse electrostrictive strain, S=-3.0×10-4, was induced under an applied electric field of 10 kV/cm.
Photorefractive Response Characteristics and Generation of Phase-Conjugate Wave in Bi12GeO20 and Bi12SiO20 Crystals
Authors: Yoshihara Toshiyuki , Uesu Yoshiaki , Hikita Kazuyasu , Iizuka Hiroyuki
Published: February 2005

The response time of the photorefractive effect in Bi12GeO20 was evaluated for the first time using nearly degenerate two-wave mixing. The result was analyzed in the context of the charge transport theory and the trap density was determined as N
A=2.4×1021 m-3. It was also found that an optimum amplitude of the displacement of the piezomirror exists in the moving-grating method. By adopting this amplitude, the reflectivities of the phase-conjugate wave reached 490% and 430% for Bi12SiO20 and Bi12GeO20, respectively.
Spectroscopic Ellipsometry Study of (111) and (100)Si Surfaces Etched in Aqueous KOH Solution
Authors: Adachi Sadao , Tomohiro Ikegami Tomohiro Ikegami , Katsuyuki Utani Katsuyuki Utani
Published: February 2005

Spectroscopic ellipsometry (SE) has been used to investigate etching characteristics of (111) and (100)Si surfaces in aqueous KOH solution. A linear regression analysis and an effective medium approximation indicate that when a native SiO
x
(SiO2) layer is partly etch-removed, the resulting surface is very rough. Just after the SiO
x
layer is etched away completely, the SE data yield the spectrum of a nearly flat Si surface. The order of the degree of roughness is found to be (100)Si>(111)Si. It is also shown that surface roughening can be greatly suppressed with magnetic stirring.
Coaxial Impact Collision Ion Scattering Spectroscopy Measurements of As/Si(100) Structure Prepared by Ionized Cluster Beam Method
Authors: Shinohara Makoto , Saraie Junji , Ishiyama Osamu , Ohtani Fumihiko , Mitamura Shigehiro
Published: February 2005

The surface structure of a Si (100) substrate exposed to an As ionized cluster beam (ICB) prior to epitaxial growth of GaAs was investigated by means of coaxial impact collision ion scattering spectroscopy (CAICISS). As a result of the measurement, first, it was proven that both As and Si dimers were formed after As ICB exposure. Second, both As and Si atoms form double domains of 2×1 and 1×2, and both As and Si areas of one domain are larger than those of the other domain in the case of a 3°-off Si substrate. Furthermore, it is likely that As atoms terminate Si atoms as if the As atoms replace the top Si layer. Third, the Si surface is not damaged by As ICB exposure, and the As ions seem to be implanted to the substitutional sites.
Recombination Radiation as Possible Mechanism of Light Emission from Reverse-Biased p-n Junctions under Breakdown Condition
Authors: Kitao Shoji Yamada
Published: February 2005

There are two models, recombination and bremsstrahlung models, proposed for the interpretation of visible light emission from reverse-biased semiconductor junctions under breakdown conditions. The emission spectra are calculated on the basis of these two models and compared with the published experimental results on Si and Ge p-n junctions. Experimental spectra can be interpreted well using the model of recombination between conduction-band electrons and valence-band holes. The spectra calculated on the basis of the bremsstrahlung model cannot be fitted to the experimental ones.
Color Image Formation Using Polymer-Dispersed Cholesteric Liquid Crystal
Authors: Kato Kinya , Tanaka Keiji , Shinji Tsuru Shinji Tsuru , Shigenobu Sakai Shigenobu Sakai
Published: February 2005

A color image has been successfully formed on a stack of polymer-dispersed cholesteric (chiral nematic) liquid crystal (PDCLC) films. A combined image through the stack of PDCLC films that reflect at different wavelengths was simultaneously formed by spot heating using an infrared laser beam while controlling the electric field applied to each film. The image is written by an electric-field-assisted thermal process, in which, after partial heating, regions cooled with a field become selectively reflective and regions cooled without a field become transparent. A combined image on a two-layer stack of PDCLC films showed the feasibility of color image formation. A memory effect maintains the image for a long period without any holding techniques, and the image can easily be changed, hence, the stack of PDCLC films can be used repeatedly.
Crystal Structure and the Role of Covalency in Eight-Layered Hexagonal Ba2CrTaO6
Authors: Choy Jin-Ho , Hong Seung-Tae , Jae-Hyun Park Jae-Hyun Park , Dong-Kuk Kim Dong-Kuk Kim
Published: February 2005

According to the Rietveld refinement, the perovskite-related Ba2CrTaO6 was found to have a P63/mmc space group with lattice constants of a=5.7383(1) and c=18.7832(2) Å. The Cr and Ta ions are completely ordered; the face-shared octahedra are occupied by Cr ions and the corner-shared octahedra by Ta ions. The increased covalent bonding nature of (Cr-O-Cr) and/or (Cr-Cr) bonds via π(εgπ-p
π-εgπ) and σ(a
1g-a
1g) would be the main driving force to stabilize the 8-layer hexagonal structure. The existence of such covalent bondings was confirmed by the ESR spectroscopic analysis and magnetic susceptibility measurement. The XANES spectra for Ta LIII-edge indicated that such a covalency induces a relatively weak covalency of competing (Ta-O) bond.
Characterization of Homoepitaxial Diamond Films Grown from Carbon Monoxide
Authors: Mori Yusuke , Yagi Hiromasa , Deguchi Masahiro , Sogi Tadayuki , Yokota Yoshihiro , Eimori Nobuhiro , Yagyu Hiroyuki , Ohnishi Hisao , Kitabatake Makoto , Nishimura Kazuhito , Hatta Akimitsu , Ito Toshimichi , Hirao Takashi , Takatomo Sasaki Takatomo Sasaki , Akio Hiraki Akio Hiraki
Published: February 2005

The crystallinities and electrical properties of homoepitaxial diamond films grown from carbon monoxide have been investigated. The films were grown on high-pressure synthesized diamond (100) and (111) substrates by microwave plasma chemical vapor deposition, and were characterized by means of atomic force microscopy, reflection high-energy electron diffraction, cathodoluminescence, secondary electron microscopy and Hall effect measurement. The (100) films were smooth, whereas films grown on the (111) substrate became rough. The boron-doped (100) film also exhibited Hall mobility of 451 cm2/Vs.
Adhesion Enhancement of Thin Film Deposits by Chopping
Authors: Puri Vijaya Puri
Published: February 2005

The chopping technique has been successfully used to enhance the adhesion of MgF2, ZnS and copper films. Chopping does not appreciably alter the adhesion of aluminium and chromium films. Chopping seems to increase the surface mobility of adatoms and prevent growth of large crystallites whereby producing more defect-free thin films because of higher relaxation leading to higher adhesion. The adhesion of chopped MgF2 and ZnS films compare well with those deposited on heated substrate and after glow discharge cleaning. The enhanced adhesion of copper films is being explained in terms of enhanced oxygen affinity at interface similar to that observed for aluminium and chromium. Chopping technique might provide a simple and cost effective process of depositing good adherent thin film coatings.
Influence of Standing Waves on Impurity Analysis of Si(001) Wafer Using Commercially Available Total-Reflection X-Ray Fluorescence Analyzer
Authors: Yakushiji Kenji , Ohkawa Shinji , Yoshinaga Atsushi , Harada Jimpei
Published: February 2005

In the analysis of trace impurities (on the order of 1010 atoms/cm2) on Si wafer surfaces using the commercially available total-reflection X-ray fluorescence analyzer, the X-ray fluorescence radiations are enhanced for the particular incident azimuth at which the evanescence beam penetrating into the Si wafer satisfies the Bragg condition. We investigated whether the enhancement of fluorescence radiation is due to the standing waves formed inside and outside the wafer surface. It is shown, using a sample which is intentionally contaminated with Zn, that the intensity enhancement is not directly connected with this phenomenon.
Behavior of Time-Resolved Ion Energy Distribution Functions during Ion-Ion Instability
Authors: Saitou Yoshifumi , Nakamura Yoshiharu , Tanaka Masayoshi , Akio Komori Akio Komori , Yoshinobu Kawai Yoshinobu Kawai
Published: February 2005

When an external RF field is applied to an ion beam plasma system, ion-ion instability is suppressed at f/f
ii\gtrsim1, where f and f
ii are the frequency of the external RF field and the peak frequency of the instability, respectively. It is also observed that the time-averaged energy distribution function of the ion beam broadens when the instability is suppressed. In order to investigate the cause of this broadening, time-resolved energy distribution functions of ions are measured with a boxcar integrator. As a result, it is found that the energy distribution functions periodically change with the external RF field and the above broadening is apparently caused by the time-averaging of the energy distribution functions.
Calibration Experiments of a Thin Manganin Gauge for Shock-Wave Measurement in Solids: Measurements of Shock-Stress History in Alumina
Authors: Akira Nakamura Akira Nakamura , Tsutomu Mashimo Tsutomu Mashimo
Published: February 2005

A thin-type manganin piezoresistance gauge was calibrated for the highly time-resolved measurements of the stress histories under shock compression of solids in the several 10 s of GPa region. The final total gauge thickness can be reduced to 25-30 µm to improve time resolution. The calibration experiments were performed using alumina stress medium by means of the inclined-mirror method using a new high-speed streak camera combined with a powder gun. The stress histories in alumina polycrystal were measured, in which the elastoplastic transitions were detected at rise and release. The relationship between the resistance change and shock stress was closely described as ΔR/R
0=-0.0329+0.0276σ
x
(R
0: zero pressure resistance, ΔR: resistance change, and σ
x
: peak shock stress). It was confirmed that the present modified gauge was applicable in the pressure range up to over 40 GPa.
In Situ Infrared Study of Surface Oxide Formation on Gas-Evaporated Si Microcrystals
Authors: Hayashi Shinji , Kawata Satoshi , Kim Han Min , Keiichi Yamamoto Keiichi Yamamoto
Published: February 2005

Infrared absorption of gas-evaporated Si microcrystals has been measured in situ. The spectra showed an absorption band attributable to the Si-O-Si stretching vibration, thereby demonstrating the formation of surface oxides in the evaporation chamber. The present in situ measurements further revealed the formation of various Si-H bonding groups which could not be clearly observed in the samples exposed to air. The surface oxide layers containing Si-H bonding groups are thought to grow during the gas-evaporation process through the reaction of evaporated Si atoms with residual O2, H2 and H2O molecules. The evolution of the oxide to form native oxide layers was also studied by monitoring the changes in absorption spectra upon exposure to air. It was found that the oxidation of the Si microcrystals proceeds much more slowly than in Si wafers.
Crystalline Fraction of Microcrystalline Silicon Films Prepared by Plasma-Enhanced Chemical Vapor Deposition Using Pulsed Silane Flow
Authors: Kaneko Toshiki , Onisawa Ken-ichi , Wakagi Masatoshi , Yoshiaki Kita Yoshiaki Kita , Tetsuroh Minemura Tetsuroh Minemura
Published: February 2005

Microcrystalline silicon (?c-Si) films have been prepared at 200?C by radio-frequency (rf: 13.56 MHz) plasma-enhanced chemical vapor deposition using pulsed silane flow. The crystalline fraction, X
c(Raman), of ?c-Si films approximately 200 nm thick is quantitatively determined by decomposing Raman spectra into three peaks: crystalline, intermediate (small-grain-size-crystalline), and amorphous. The effects of rf power on X
c(Raman) and hydrogen content, C
H, have been studied. X
c(Raman) increases with increasing rf power and tends to saturate; the maximum value of X
c(Raman) is 71%. With increasing rf power C
H decreases to a minimum value of 4.5% and then increases. Hydrogen introduction into Si films overlapped with hydrogen elimination is responsible for the increase and saturation of X
c(Raman) with rf power.
Analytical Models for Symmetric Thin-Film Double-Gate Silicon-on-Insulator Metal-Oxide-Semiconductor-Field-Effect-Transistors
Authors: Suzuki Kunihiro , Satoh Shigeo , Tetsu Tanaka Tetsu Tanaka , Satoshi Ando Satoshi Ando
Published: February 2005

We derived analytical models for the current-voltage characteristics of double-gate silicon-on-insulator metal-oxide-semiconductor-field-effect-transistors. In the subthreshold region, we derived an analytical subthreshold slope model considering both depleted and induced charges. We proposed a unique definition of threshold voltage of the device, and showed that the threshold voltage is close to the experimentally defined threshold voltage at which the drain current has a specific value. The variation in the surface potential after the threshold voltage was modeled, and hence the models are valid in the moderate-inversion region as well as in the strong-inversion region. The models agree well with experimental data.
In-Ag-Te-Sb Phase Change Recording Media at Compact Disk Linear Velocity
Authors: Handa Tokuhiko , Tominaga Junji , Susumu Haratani Susumu Haratani , Suguru Takayama Suguru Takayama
Published: February 2005

The feasibility of In-Ag-Te-Sb phase change recording media was investigated at an actual compact disk (CD) linear velocity. The composition of 0.5 at% V-doped In3.8Ag12.4Te28.8Sb55.0 was used for the recording layer which we have reported previously. To improve the repetition property of overwriting, the disk structure was modified so that the cooling rate of the disk was increased. Consequently, recording jitter of less than 30 ns and modulation of more than 60% were maintained up to 2000 repetitions of overwriting when eight-fourteen modulation (EFM) signal with pulse-train division was applied.
High Density Magneto-Optical Recording with a Second-Harmonic Generation Green Laser
Authors: Ichimura Isao , Sabi Yuichi , Takeshita Yasuyuki , Fukumoto Atsushi , Masahiko Kaneko Masahiko Kaneko , Hideo Owa Hideo Owa
Published: February 2005

Tripled areal density optical recording was realized with the combination of a high power laser-diode pumped intracavity frequency-doubled Nd:YAG laser (SHG green laser), a low noise GdFeCo/TbFeCo double-layered magneto-optical (MO) disk, and high sensitivity photodetectors optimized for the wavelength of the light source. A high carrier-to-noise (C/N) ratio of more than 48 dB and a bit error rate of less than 3×10-6 by (2, 7) run-length-limited (RLL) mark position recording was obtained at a mark length of 0.45 µm (0.6 µm/bit) for a disk with a 0.9 µm track pitch.
Edge Shift Characteristics of a Magnetooptical Edge Detection Signal
Authors: Yamaguchi Eiji , Yamamoto Masakuni , Hoshi Hiroaki , Matsumura Susumu
Published: February 2005

We implemented a magnetooptical edge detection system using split sensors. We measured the carrier-to-noise ratio and edge shift quantity of readout signals. The edge shift quantity steeply increases when a recorded domain length in the information track direction becomes shorter than half the diameter of the reading light spot. The edge shift difference between the conventional detection signal and the edge detection signal is discussed.
2.5 Inch Flat-Type Phase-Change Optical Disk Drive
Authors: Minemura Hiroyuki , Sato Yoshio , Tsuboi Nobuyoshi , Sugita Tatsuya , Fushimi Tetsuya , Yasukawa Saburoh , Andoh Hisashi , Muto Nobuyoshi , Kugiya Fumio , Yoshito Tsunoda Yoshito Tsunoda
Published: February 2005

Downsizing of personal information processing devices such as notebook computers has been progressing rapidly, hence a media exchangeable personal memory device with a large storage capacity is needed. We propose a 2.5 inch flat-type, phase-change optical disk drive of 15 mm in height. In order to decrease the drive height we have designed and developed a 0.6 mm polycarbonate substrate, phase-change optical disk medium, and a 6 mm high flat-type optical head. Overwriting on the 2.5 inch phase-change medium was performed using the prototype disk drive.
Advanced Direct Seeking System for 5.25” Magnetooptical Disk Drive
Authors: Suzuki Motoyuki , Tanaka Hisamitsu , Miura Michio , Suzuki Yoshio , Mori Masashi , Takasago Masahiro , Tomono Youji
Published: February 2005

In order to realize high-speed access using a direct seeking system, new methods of tracking error signal transformation, relative velocity detection, and double window detection have been developed. These methods were applied to a 5.25” magnetooptical disk drive, and a direct seeking system whose counting error is less than one track was realized.
Arsenic Coverages and Surface Structures of As-Stabilized GaAs (001) Surfaces during Metalorganic Chemical Vapor Deposition Observed by Reflectance Difference
Authors: Uwai Kunihiko , Saito Hisao , Yoshiharu Yamauchi Yoshiharu Yamauchi , Naoki Kobayashi Naoki Kobayashi
Published: February 2005

We study temporal evolutions of surface anisotropy change detected optically at wavelengths of 633 nm and 488 nm during the formation of Ga-stabilized surfaces to characterize As-stabilized (001) GaAs surfaces grown by metalorganic chemical vapor deposition (MOCVD). Using the evolution of Ga dimer concentration, we find that effective As coverages, which are defined as the amount of As on the surface that can be incorporated into the crystal, are close to 1 for the c(4×4) surface and As-richer surfaces, although these surfaces have actual As coverages of more than 1. We also find that three kinds of well-defined As-stabilized surfaces with different As coverages, c(4×4)+α, c(4×4), and (2×4), can exist in MOCVD environments depending on the AsH3 partial pressures, with c(4×4)+α being a c(4×4)-like surface with additional As. A fast As desorption with a time constant of <0.5 s at 600°C and at 570°C accompanies the conversion from c(4×4)+α to c(4×4). Another As desorption with a time constant of 2 s at 600°C and 4 s at 570°C accompanies the conversion from c(4×4) to the least-As-rich (2×4) surface with θAs=0.6-0.7.
A Study on the Flux Pinning Anisotropy in Nb/Al2O3 Superconducting Multilayers
Authors: Ikebe Manabu , Obi Yoshihisa , Fujimori Hiroyuki Fujishiro
Published: February 2005

The critical currents of the Nb/Al2O3 multilayers have been measured under parallel and perpendicular magnetic fields. The anisotropy of the pinning force is investigated as a function of thickness of both the Nb and Al2O3 sublayers. The pinning force under the parallel field is more markedly enhanced in the multilayers with the thinner Nb layer in the two-dimensional superconductivity region.
Decrease in Quasi Vacancy Formation Energy in the Study of Pair Diffusion Model of Group V Impurities in Silicon
Authors: Masayuki Yoshida Masayuki Yoshida
Published: February 2005

When the impurity concentration is high, every vacancy is under the influence of impurity atoms and the vacancy formation energy appears to decrease due to the interaction between a vacancy and two impurity atoms. Since the vacancy formation energy is defined under the condition of no influence of impurity, the decrease is called a decrease in quasi vacancy formation energy, showing that a vacancy is under the influence of impurity atoms.
Amorphous CdI2 Films and Their Crystallization Studied by Simultaneous Measurements of Optical Absorption and Reflection
Authors: Kondo Shin-ichi , Shin-ichiro Kagawa Shin-ichiro Kagawa , Tadaaki Saito Tadaaki Saito
Published: February 2005

Amorphous CdI2 films with excellent transmittance below the absorption edge were obtained by quench-deposition onto 77 K substrates. By annealing at 300-340 K, they crystallized in a previously unknown crystal structure which exhibited a very sharp exciton peak at 3.934 eV. It was suggested that the films, amorphous or crystalline, were due to covalent bonds between Cd and I atoms. The covalent bonds brought about small values of the real part of refractive index. Further annealing at higher temperatures transformed the crystal structure of the films to the ordinary, CdI2 structure. The resultant films showed anomalous spectral behavior leading to a new understanding of crystallinity in the films.
Composition of Evaporated Boron Nitride Films by Carbon Dioxide and Excimer Laser
Authors: Kayo Kaneda Kayo Kaneda , Kimihiro Shibata Kimihiro Shibata
Published: February 2005

This paper presents a comparison of the chemical composition of boron nitride (BN) films formed by physical vapor deposition using two lasers operating at different wavelengths. The lasers used were a carbon dioxide (CO2) laser, operating in the infrared region, and a KrF excimer laser, operating in the ultraviolet region. A BN target irradiated with the CO2 iaser showed an absence of nitrogen and the deposited film was composed nearly entirely of metallic boron. On the other hand, the BN film deposited with the excimer laser was virtually stoichiometric. A stoichiometric film was also obtained with the CO2 laser when an RF plasma discharge was applied between the target and the substrate. However, the spectra of X-ray photoelectron spectroscopy (XPS) of the film deposited with the excimer laser showed a narrower peak width at half height and the film had a more homogenous BN composition.
Electron Linear Accelerator Based on the Crossed-Wave Electric and Static Magnetic Field
Authors: Yugami Noboru , Onihashi Hiroshi , Otsuka Kazue , Taura Tohru , Yasushi Nishida Yasushi Nishida
Published: February 2005

A new type of linear electron accelerator, based on the crossed-wave-electric field and static magnetic field system known as the vp
×B acceleration mechanism observed originally in plasma, has been demonstrated in vacuum for the first time. In this scheme a static magnetic field is applied vertically to direction of the wave propagation and the particles are accelerated along the wavefront in a constant phase with respect to the wave. The present machine can be either a conventional linear accelerator or a new type of vp
×B accelerator without any modification. An energy gain of 12.8 keV for electrons is observed from an incident energy of 66 keV in a 0.5 m accelerator, when an external magnetic field of 2.5 G is applied. The energy gain is 30% higher than that of conventional linacs. The energy gain is proportional to the square of the applied magnetic field strength B
0$as long as the electrons are trapped within a wave trough. Experiments have been carried out with two different RF power levels in order to confirm the trapping condition for electrons, which depends on both the electric field and the applied magnetic field. The results of experiments and theories are in fairly good agreement.
Analysis of Hard X-Ray Continuum from Hot Electrons in Nagoya Bumpy Torus
Authors: Yuyama Tetsumori , Michishita Toshinori , Hosokawa Hiroshi Kubo
Published: February 2005

The average kinetic energy, <E

k
>, and the density, n
h, of hot electrons of plasma produced by ECH (Electron Cyclotron Heating) in the Nagoya Bumpy Torus-1M are deduced from hard X-rays. In the analysis, collisions between hot-electrons and cold bulk electrons are included, which reduce the line-integrated density n
h·l by about 25% compared to the case neglecting the collisions. The relativistic cross section for bremsstrahlung and the response function of NaI(Tl) are also taken into account. By these analysis methods, <E

k
> and n
h as functions of the injected ECH power P
o and filling gas pressure p
r are obtained, e.g., <E

k
>=2 MeV and n
h·l=1-4×1012 cm-2 (l∼10 cm) at P
o=40 kW and p
r=1-8×10-5 Torr.
Discrimination of Taste of Amino Acids with a Multichannel Taste Sensor
Authors: Kikkawa Yukiko , Toko Kiyoshi , Tetsuya Matsuno Tetsuya Matsuno , Kaoru Yamafuji Kaoru Yamafuji
Published: February 2005

Taste of amino acids was studied using a multichannel taste sensor with lipid membranes as the transducer of taste substances. The study on taste of amino acids has drawn much attention so far because each of them elicits complicated mixed taste. The response of the sensor to amino acids was compared with results of panel tests, and response potentials from the eight membranes were transformed to terms representing five basic tastes by multiple linear regression. This expression of five basic tastes reproduced human taste sensation very well. The taste was expressed more quantitatively by assuming new channels, which are represented by multiplication of the response potentials of the original channels. This new set of channels implies the existence of processes involving the nervous system which is connected with taste cells.
Optimum Trap Numbers of Comb Filters for Measuring Phase Velocity of Surface Acoustic Waves
Authors: Makoto Hirabayashi Makoto Hirabayashi
Published: February 2005

A method for precise measurement of the phase velocity of surface waves on highly dispersive substrates is reported. Lithium niobate covered with aluminum oxide, whose thickness-wavelength ratio was 0.026, was used for the substrate. An approximate value of the velocity was measured using tapped delay lines. The optimum trap numbers of the frequency responses were determined by substituting the approximate value into an equation. The optimum value of the velocity was calculated from the trap numbers and the measured trap frequencies of about 125 MHz. Experimental results for the velocity of about 4015 m/s showed that the optimum trap numbers were correct.
High-Sensitivity Image-Sensor-Incorporated Image Intensifier Tube with Charge-Coupled Device for X-Ray Diffraction
Authors: Nakajima Kunio , Aoki Shuzo Sudo
Published: February 2005

The construction and performance of the two-dimensional X-ray detector are described for X-ray diffraction. The detector consists of an input fluorescent screen, an image intensifier tube and a charge-coupled device (CCD) image sensor, which is coupled using fiber-optics. The background noise of the detector is about 10-3 of the saturation peak, and the linearity range is about two orders of magnitude for the incident X-ray photons. The observation of the diffraction images with a low X-ray dose is demonstrated using this detector.
Ultrafine-Particle Beam Deposition III: Applications to Thermoelectric Materials
Authors: Kizaki Yoshimi , Hiroshi Osada Hiroshi Osada , Hiroshi Aoki Hiroshi Aoki
Published: February 2005

In an attempt to demonstrate a wider applicability of our handling technique of ultrafine particles, called “ultrafine particles beam deposition,” the following procedures were applied to prepare films composed of elements such as Fe, Si and/or O, which possess thermoelectric properties: (i) preparation of iron silicide alloy film derived from FeSi2+x
(-1<x<1) alloyed ultrafine particles; (ii) film formation under reactive oxidation of FeSi2+x
(0<x<1) ultrafine particles; (iii) twin-beam deposition comprising independent Fe and SiO ultrafine-particle beams. Within the limitations of our experiments, the films prepared by the third procedure were found to exhibit a Seebeck coefficient and electric conductivity very close or superior to those of the corresponding bulk material.