bluuebunny/crossref_metadata_2025 huggingface dataset:
Radical Generation Mechanism and Radical Effect on Aluminum Anisotropic Etching in SiCl4 Reactive Ion Etching
Authors: Sato Masaaki , Nakamura Hiroaki , Yoshikawa Akira , Arita Yoshinobu
Published: November 2005

The radical generation mechanisms and the effect of radical composition in a SiCl4 discharge on the directionality of aluminum etching are discussed using the results of optical emission spectra and plasma density measurements. It was found that the chlorine radical concentration is almost proportional to gas pressure and plasma density, while the silicon radical density is almost proportional to the square of the plasma density, but is weakly dependent on the gas pressure. At lower pressure or a higher power density, where the ratio of silicon radical concentration to chlorine radical concentration increases, lateral side etching is inhibited by the silicon deposition, and anisotropic etching can be achieved. From these experiments, it is concluded that a control of gas dissociation is needed for a more precise control of the anisotropic etching.
sKinetics of the Subtransition of Multilamellar Dipalmitoylphosphatidylcholine
Authors: Akiyama Morio , Matsushita Norio , Terayama Yoshio
Published: November 2005

An X-ray diffraction method was used to study the kinetics of the conversion of Lβ' phase\rightleftharpoonsLc phase in 1,2-dipalmitoyl-L-phosphatidylcholine (DPPC) dispersions. The time course of conversion after a rapid temperature change did not follow a simple monotonous function, such as an exponential function. There were three time domains during the course of conversion. In the first time domain, rapid changes in the hydrocarbon chain packing and the repeat period of lamellar stacking were observed. In the second time domain, remarkable changes could not be observed. In the third time domain, gradual changes were observed. Except for the first time domain, the time course traced a sigmoid curve. This fact suggests the existence of a cooperative interaction in the arrangement of lipid molecules. A tentative theory of transition kinetics based on lenient cooperativity is proposed in this paper.
The Electrical Properties of a SrTiO3 Bicrystal Joined by Thin Film of a Molten Bi2O3
Authors: Fujimoto Masayuki , Yamaoka Nobutatsu , Shirasaki Shinichi
Published: November 2005

A niobium-doped SrTiO3 single crystal was grown using the FZ (floating zone) method. The single crystal was sliced in two, and the two halves were joined by thin film of Bi2O3 which was sandwiched between the two half-crystals at a high temperature (1400°C). The electrical properties of the obtained bicrystal were similar to those of a SrTiO3 IBL capacitor. The bicrystal was considered to be applicable to the study of ceramic grain boundary properties.
Determination of Hydrogen Concentration in PCVD Silicon Nitride Films by Elastic Recoil Detection Analysis
Authors: Takahashi Mitsutoshi , Maeda Masahiko , Sakakibara Yutaka
Published: November 2005

The hydrogen concentrations of PCVD silicon nitride films were measured by Elastic Recoil Detection (ERD) analysis using 2.5 MeV He+ ions. For annealed films, H concentrations measured by ERD analysis are smaller than those measured by an infrared absorption analysis. These results indicate that absorption cross sections of Si-hydrogen and N-hydrogen bonds are changed by annealing.
Numerical Analysis Method for Orientation Structures of Surface-Stabilized Ferroelectric Liquid Crystals
Authors: Nonaka Shiro , Ito Kumiko , Isogai Masato , Odamura Motomi
Published: November 2005

A computer simulation method for analyzing the dynamic orientation structures of surface-stabilized ferroelectric liquid crystals is presented. This method is based on a free-energy theory in which electrostatic, elastic distortion and surface interaction energies are taken into account. Some results of one-dimensional simulations which analyzed the relationships between the threshold of an applied electric field, material constants, bounding surface conditions and cell thickness are also presented and compared to theoretical considerations.
Fabrication of Polar Structures by Use of LB Technique
Authors: Nakanishi Hachiro , Okada Shuji , Matsuda Hiro , Kato Masao , Sugi Michio , Saito Mitsuyoshi , Iizima Sigeru
Published: November 2005

The fabrication of polar structures of thin films has been demonstrated for the molecular moieties of 2-methy1-4-nitroaniline and two diacetylenes, by alternately depositing their and arachidic acid's monolayers. It has been found that the packing of one of the diacetylenes in such a polar film differs from that in the single component Y-type film, resulting in a different polymerization behavior.
A Pseudopotential Approach to Thermal Instability of III–V Semiconductor Superlattices
Authors: Ito Tomonori
Published: November 2005

The thermal instability of III–V semiconductor superlattices, dominated by interlayer diffusion without impurities, were investigated using a pseudopotential perturbation approach. The emthalpies and Gibbs energies of the activation process for the disordering were calculated by assuming simple hypothetical atomic migration models. The calculated activation enthalpies were found to be related to the bulk moduli and atomic volumes of the superlattices based on the elastic diffusion model. Theoretically estimated Gibbs energies of the activation processes were compared with experimental results. The III–V monolayer superlattice systems with larger elastic stiffness and atomic volume were concluded to be more thermally stable than those with smaller elastic stiffness and atomic volume.
Correlation between Magnetic Properties and Composition of Electroless-Plated Cobalt Alloy Films for Perpendicular Magnetic Recording Media
Authors: Osaka Tetsuya , Koiwa Ichiro , Okabe Yutaka , Yamanishi Keisuke
Published: November 2005

The magnetic properties of a perpendicular magnetic anisotropy film prepared by an electroless plating method was investigated, from viewpoints of film composition. The value of saturation magnetization, M
s, of the film decreases (9.4 emu cm-3, 30.8 emu cm-3 and 27.0 emu cm-3) by one atomic percentage codeposition of nickel, rhenium and phosphorus, respectively. The codepositions of nickel and phosphorus decrease the value of the perpendicular anisotropically magnetic field, H
k. Simultaneously, however, for the low-cobalt-content region with high Ni content, the codeposition of rhenium increases H
k while decreasing M

s
, making it possible to prepare perpendicular anisotropicallymagnetic films. Therefore, in the electroless plating method, lower M
s conditions with high Ni content is advantageous for making perpendicular anisotropically magnetic films.
Magnetostatic Perpendicular Anisotropy in Iron Films with Columnar Structure
Authors: Masuda Morio , Shiomi Shigeru , Shiraki Makoto
Published: November 2005

Theoretical calculations are given for the uniaxial perpendicular anisotropy resulting from the magnetostatic energy in magnetic films with a columnar structure; small magnetic cylinders are assumed to form an infinite two-dimensional array with hexagonal symmetry. Experiments have also been done for the dependence of the uniaxial perpendicular anisotropy on the temperature and columnar-structure constants in the iron films prepared by an anodic oxidation method. The experimental results could be well interpreted in terms of the magnetostatic uniaxial anisotropy.
A Note on the Band-Folding Effects in the (GaAs)n/(AIAs)1, (GaAs)1/(AIAs)n(n=1∼10) Superlattices
Authors: Nara Shigetoshi
Published: November 2005

The electronic band structures of (GaAs)
n
/(AIAs)1 and (GaAs)1/(AIAs)
n
(n=1∼10) superlattices were investigated by means of an improved tight-binding method in which the overlap integrals up to the second nearest-neighbor atoms, including new parameters, were explicitly taken into account. Kroemer's rule for the band offset value was employed. The resulting band structure of superlattices in the extended zone scheme were compared with the bulk band structure while paying attention to the band-folding effect due to a periodic insertion of one atomic monolayer. A possibility of transforming an indirect-gap material into a direct-gap material by such artificial insertion of another material is discussed and the optical oscillator strength at the Γ-point is estimated for each n.
Self-Aligned Inversion-Mode lnP MISFET
Authors: Oigawa Kinya , Uekusa Shin-ichiro , Sugiyama Yoshinobu , Tacano Munecazu
Published: November 2005

A self-aligned-gate inversion-mode InP metal-insulator-semiconductor field-effect transistor (MISFET) was successfully fabricated by using plasma-assisted chemical-vapor-deposited Si3N4 film both as the insulator and as the capping layer for the annealing process. A channel mobility of 2700 cm2/Vs and a transconductance of 55 mS/mm at a gate voltage of 4 V were achieved with a reasonably low source-drain leakage current.
Time and Position Resolution of a Coaxial Germanium Detector by the Least-Squares Fitting of the Waveform
Authors: Toyoshima Kouichi
Published: November 2005

The time resolution of a coaxial Ge(Li) detector was improved by determining the time of interaction by a leastsquares fitting of the digitized waveform. An FWHM of 14.6 ns was obtained for 122 keV γ-rays by a 42 mm-diameter detector. Position information was simultaneously obtained by this method.
An Improved Czochralski Technique for Growing Single Crystals with High Homogeneity
Authors: Kumagawa Masashi , Tamaki Makoto , Hayakawa Yasuhiro
Published: November 2005

InSb single crystals with high homogeneity were grown by an improved Czochralski technique. The distinctive feature of this technique is that a seed crystal is rotated alternately clockwise and counterclockwise within a narrow range of angles. The periodic fluctuation of the growth rate in InSb pulled crystals was remarkably decreased and, as a result, the impurity inhomogeneity was reduced.
Reduction and Sintering of Vanadium Oxide Films by Laser-Beam Irradiation
Authors: Okabe Katsuya , Mitsuishi Tomokuni , Sasaki Yosisato
Published: November 2005

V2O5 films printed on alumina substrates were reduced and sintered to form film devices by a 2 ms irradiation process using a beam from a relaxation-oscillating ruby laser in an air atmosphere. These devices possess electrical characteristics of a metal-semiconductor transition at 68°C, referred to as VO2. Their X-ray powder diffraction patterns prove that they consist mainly of VO2. This process is useful for making a VO2 element at a specified location on a device.
Temperature and Magnetic Effects on the Work Function of a Ni(100) Surface
Authors: Saito Shigeru
Published: November 2005

The influence of ferromagnetism on the work function (WF) was studied by measuring the contact potential difference of a Ni(100) face, with an accuracy of ±0.5 meV. A decrease of the WF with temperature (approximate coefficient: -1.83×10-4eV/°C) and an anomalous change near the Curie point were found. By extrapolation from the paramagnetic region, the magnetic effect on the WF was estimated to be 2∼3 meV. These experimental results are explained as the combined effect of thermal expansion and spontaneous volume magnetostriction.
Exhaust of NOx from High-Temperature Wind Tunnels
Authors: Matsuzaki Ri'ichi
Published: November 2005

Theoretical calculations were performed in order to estimate the concentrations of three main constituents of NOx (NO, NO2 and N2O) in the exhaust gas produced by two kinds of hypersonic wind tunnels. One of them had an arc-heater, and the other a pebble-heater. Estimations were performed for the equilibrium air in the plenum chamber, for the equilibrium and nonequilibrium nozzle flows, and for the final exhaust gas. Measurements in the exhaust gas of the arc-heated wind tunnel show that the total concentration of NOx (NO and NO2) was of the order of 10,000 ppm, depending on the conditions of operation. Two simple models are proposed to explain the origin of such a high level of NOx in the exhaust. It is shown that a model taking account of the isothermal compression of the exhaust gas in rotary pumps of the vacuum system can predict the formation of high concentrations of NOx.
Studies on the Electronic Energy States of Germanium Microcrystal and the Chemical Shift due to Surface Oxidization by Means of Photoelectron Spectroscopy
Authors: Arai Toshihiro , Tagawa Reiji
Published: November 2005

The energies of electronic states in the germanium microcrystals which were made by evaporation in inert gas (He) at low pressure were deduced from the photoelectron spectra induced by X-ray and ultraviolet irradiations. The valence band structure of the microcrystal which has the size ca. 4 nm in diameter was similar to that of the amorphous state. The origin may be due to a change in the many-body effect, an interaction between a hole and an electron, and/or multi-scattering of an electron originating in the imperfection in the structure of a microcrystal. The energies of inner-core electrons of a microcrystal which has size ca. 4 nm were the same as that of the bulk. The chemical shift due to oxidization of a powder-like microcrystal differs from that of the bulk surface.
Dynamics of Helix Winding, Unwinding and Switching of Ferroelectric Liquid Crystals
Authors: Bawa S. S. , Biradar A. M. , Chandra Subhas
Published: November 2005

Dynamics of helix unwinding (SmC*→SmC) and winding (SmC→SmC*) processes under the applied electric field in ferroelectric liquid crystal (FLC) have been studied by applying a biased (0 V–10 V–0 V) asymmetric square wave pulses. The molecular reorientation mechanism taking place in these processes have been compared with the switching process amonst the two stable states of FLC. The helices unwinding process which takes place under the constraint condition of electric field is much faster than the winding process which occurs with its natural way depending upon the viscosity of the material. The switching amongst the two stable states takes place directly from one state to another without actually attaining the helicoidal structure of FLC.
Spatially Resolved Ellipsometry for Semiconductor Process Control: Application to GaInAs MIS Structures
Authors: Erman M. , Renaud M. , Gourrier S.
Published: November 2005

A new assessment technique, a spectroscopic ellipsometry system with high lateral resolution (10×10 µm spot), is introduced. Its high surface sensitivity is used at each step of a typical technological process, the fabrication of GaInAs metal-insulator-semiconductor structures, namely oxide removal, etching, and dielectric deposition. The measured non-uniformity of the Si3N4/GaInAs interface quality over the wafer is directly correlated to the electrical characteristics of the devices. This is a direct proof of the influence of the native oxide at this interface upon the electrical drift of MIS structures.
Orientation and Pearl-Chain Formation of Paramecia Induced by AC Electric Field
Authors: Hatakeyama Toyomasa , Tanji Ayafumi , Yagi Hiroshi
Published: November 2005

Paramecium deciliated with ethanol is able to orient itself in a parallel (positive orientation) or perpendicular direction (negative orientation) to an AC electric field, depending upon the applied frequency. We found that this turnover frequency is between 1 and 10 MHz in a non-electrolyte solution for the cells. The cells also aggregate with one another by the mutual dielectrophoresis in the electric field, provided the distance between the two cells is shorter than about half their length. The two critical field intensities for the orientation and for the aggregation cannot be clearly distinguished. Consequently, when the cell density in the solution is sufficiently high, a positive or negative pearl-chain of the cells is formed, depending upon the applied frequency.
A Dual-Type Cell for Ultrasonic Measurements of Ceramics
Authors: Kamioka Hiroaki
Published: November 2005

A dual-type cell was designed for measuring the velocity and attenuation of sound in highly dissipative materials such as ceramics. Using this new cell, longitudinal and shear wave velocities of ceramic barium titanate, BaTiO3, were precisely measured in the temperature range between room temperature and 200°C, including the Curie temperature.
A Magnetic Study of Sintering of Ultrafine Particles
Authors: Okamoto Yoichi , Koyano Yamotsu , Tasaki Akira
Published: November 2005

Sintering of Ni ultrafine particles and Cu ultrafine particles was studied by measuring the ferromagnetism of Ni. It was found that diffusion started at about 100°C and accelerated above 250°C. In a reducing atmosphere of H2, the diffusion started at a lower temperature than in a He atmosphere.
Characterization of the Structure in Hydrogenated Amorphous Silicon by Means of 119Sn Mössbauer Spectroscopy
Authors: Myoren Hiroaki , Shrestha Purushottam , Imura Takeshi , Osaka Yukio
Published: November 2005

The network structure in hydrogenated amorphous silicon (a-Si:H) films including a small amount of tin has been investigated by means of Mössbauer spectroscopy. The quadrupole splitting Δ of 119Sn nuclei in a-Si:H films is very sensitive to the difference in the hydrogen bonding configuration, and is concluded to be a useful parameter for the characterization of the amorphous structure. The relation between Δ and the IR spectra shows that the over-constrained region is formed in the a-Si:H network by the SiH group.
Nature of Oxygen Donor in Czochralski-Grown Silicon
Authors: Fukuoka Noboru , Yoneta Minoru , Miyamura Reiko , Saito Haruo
Published: November 2005

Changes in the substitutional carbon and interstitial oxygen concentrations due to the formation of oxygen donors were studied on carbon-rich Czochralski-grown silicon (7-9×1017 carbon atoms/cm3). The result suggests that the new donor formation is controlled not by the substitutional carbon concentration directly, but by a density of some unknown embryo.
A donor formation was observed in a 450°C annealing which was preceded by a 650°C annealing without new donor formation. This donor does not exhibit a 0.767 eV line in a measurement of the photoluminescence spectrum. However,it exhibits an infrared absorption band which is characteristic to the thermal donor.
Influence of Deposition Conditions on the Properties of Silicon Nitride Films Prepared by the ECR Plasma CVD Method
Authors: Hirao Takashi , Setsune Kentaro , Kitagawa Masatoshi , Kamada Takeshi , Wasa Kiyotaka , Izumi Tomio
Published: November 2005

Properties such as the refractive index, etch rate and resistivity of silicon nitride films (SiN) prepared by an electron cyclotron resonance (ECR) plasma CVD method have been studied and correlated with their compositional and structural properties such as the N/Si ratio, bond configurations, spin density and film density.
The microwave power, SiH4 flow rate under a constant flow rate of N2 gas and gas pressure during depositions, selected as the deposition parameters, were 50–500 W, 3–12 sccm and 4×10-4-4×10-3 Torr, respectively. The refractive index showed a unique correspondence to the N/Si ratio, but Si–H bonds had to be simultaneously taken into consideration in order to explain the dependency of the etch rate. The film density also had a strong influence on the film properties. The resistivity had a strong correlation with spin density, though it was also correlated with other properties such as the N/Si ratio.
The compositional and structural properties of the films can be qualitatively explained by the optical emission spectra obtained from the ECR plasma of a SiH4–N2 mixture gas.
The Annealing Effect on the Magnetic Properties of Fe–Co–B Alloy Films
Authors: Ghang Y.H. , Yung S.W. , Chin T.S. , Hung M.P.
Published: November 2005

The magnetic properties of as-deposited and annealed Fe–B, Co–B and Fe–Co–B alloy films on copper, mica, glass and NaCl single crystals were examined by a vibrating sample magnetometer. The magnetic easy direction was found to be in the plane of the films. The coercivity and magnetization of the (Fe
x
Co1-x
)2B films have maximum values when x is approximately equal to 0.5. The increases in intrinsic coercivity and saturation magnetization of the amorphous magnetic films are due to the growth of microcrystals, which depends on annealing temperature. The maximum coercivity of the annealed (Fe0.6Co0.4)2B film was found to be 170 Oe around 670 K; for Fe2B film, the maximum coercivity was 180 Oe around 560 K. The saturation magnetization parallel to the plane of the films slowly increased with increasing annealing temperature. A value of 180 emu/g of the saturation magnetization parallel to the film was obtained for an Fe2B film annealed at 773 K for two hours.
Temperature and Pressure Dependence of Disaccommodation in a Manganese Zinc Ferrite Single Crystal
Authors: Kanamaru Masayuki , Nishikiori Takuya , Kohn Kay , Sekizawa Hisashi
Published: November 2005

Disaccommodation in a Mn0.59Zn0.29Fe2.08O4 single crystal was studied in the temperature range between 270 and 300 K, and in the pressure range between 1 bar and 3 kbar. The obtained results were analyzed using a model in which the relaxation time τ is distributed with a spectrum of Gaussian type on a log τ scale. The activation energy determined from the temperature dependence of the relaxation time is 0.88 eV. The activation volume is about 2 Å3/atom and shows remarkable temperature dependence in the range studied.
Effect of a Ti Interlayer in Evaporated Co–Cr/Fe–Ni Double-Layer Film
Authors: Tanaka Toshikazu , Kanayama Etsuko , Katahira Taku , Saito Ichiro , Kawazoe Kazushige , Masuya Haruko
Published: November 2005

The effect of a Ti interlayer in an evaporated Co–Cr/Fe–Ni double-layer film on structural and magnetic properties and recording and playback characteristics has been investigated. The inplane coercivity of the Fe–Ni underlayer decreases, and the saturation magnetization and the perpendicular coercivity of the Co–Cr layer increase as a result of the presence of a Ti interlayer. The recording output voltage is found to increase as a result of the presence of a Ti interlayer from 10 to 40 nm thick. In films with an Fe–Ni underlayer having a small coercivity of about 80 A/m, the effect of the Ti interlayer as a spacing between the pole tip of a single-pole head and the Fe–Ni underlayer is observed: a higher output voltage and recording sensitivity, and a better overwrite S/N are obtained for films with a thinner Ti interlayer in the thickness range from 10 to 40 nm.
Initial Stage of Laser-Induced Selective Chemical Vapor Deposition of Silicon
Authors: Tanaka Takeshi , Deguchi Koji , Hirose Masataka
Published: November 2005

Spatially selective chemical vapor deposition has been achieved by ArF excimer laser (193 nm) irradiation through a metal mask in a Si2H6 + He gas mixture. The selective deposition kinetics has been found to be controlled by a nonthermal process and has been explained in terms of the Langmuir-Hinshelwood mechanism. Both surface migration of adsorbed radicals and desorption of reaction products appear to be enhanced with the laser irradiation, leading to a selective nucleation of silicon.
Properties of ECR Plasma in a Simple Mirror Field I–Correlation in Cold and Hot Electron Production–
Authors: Arata Yoshiaki , Miyake Shoji , Kishimoto Hiroaki
Published: November 2005

The properties of an ECR plasma in various gas species have been clarified through soft X-ray and probe measurements. Soft X-ray measurements were performed on hot electron plasmas in the energy range of 1–15 keV and hot electron parameters were determined. Using data concerning cold plasma parameters determined from probe measurements, a close correlation was found in the production and/or heating of cold and hot electron components by changing the external parameters over a wide range.
Mass and Energy Limit of Isotope Identification of Heavy Ions Using ΔE–E Silicon-Detector Telescope
Authors: Hasebe Nobuyuki , Yoshii Hisashi , Doke Tadayoshi , Nagata Katsuaki
Published: November 2005

The technical limit of isotope identification of ions heavier than iron using a ΔE–E silicon detector telescope is presented. The identification of iron or heavier ions with energies less than 30 MeV/n is limited by the nonuniformity of the thickness in a thin silicon detector, and a decrease in the effective charge of low-velocity ions passing through a silicon medium. In an energy region higher than 300 MeV/n, the slope of the stopping power for heavy ions becomes smaller, which limits the capability of isotope identification. In the intermediate energy range, some ions heavier than iron can be identified with a resolution of σm=0.22 amu; the maximum mass identifiable in this ΔE–E algorithm is about 100 amu because of the restriction of the nonuniformity of detector thickness and the straggling of the energy loss of ions passing through a silicon detector.
Wedge-Driven and Miniature Diamond-Anvil Cells for High-Pressure Optical and X-Ray Diffraction Studies
Authors: Aoki Katsutoshi , Kakudate Yozo , Yoshida Masatake , Usuba Shu , Tanaka Katsumi , Fujiwara Syuzo
Published: November 2005

This paper describes two newly designed diamond-anvil cells. The first one, applicable to powder X-ray diffraction and optical measurements, employs a wedge-driven thrust mechanism for pressure generation. This mechanism enables the fine control of the pressure and remote operation of the cell. The second one, designed for single-crystal X-ray diffraction studies, employs a screw-clamped mechanism for the sake of compactness. The operations for loading and compressing samples with this cell are facilitated by combining it with a wedge-driven cell. Their applications to X-ray diffraction measurements are presented.
A Microchannel Plate X-Ray Collimator
Authors: Yamaguchi Naohiro , Aoki Sadao
Published: November 2005

A simple and compact X-ray collimator utilizing a microchannel plate, which is a bundle of small tubes, was considered and tested using X-rays from an X-ray tube. The collimation performance has confirmed that the beam divergence is limited by the geometrical opening of a channel pore and its length (about 6 mrad in this study). Some other properties of a channel plate collimator (CPC) have been demonstrated; for instance, the CPC can transfer the source image and has a large aperture. The throughput of the CPC system has been estimated and is compared with a conventional collimation system.
Temperature Rise of Small Silicon Particles During Laser Irradiation
Authors: Okada Tadashi , Yamamoto Keiichi
Published: November 2005

The temperature of small silicon particles during laser irradiation was estimated from the Raman spectra of the particles. The relationship between the peak frequency shift and the linewidth of the experimental data was compared with a theoretical calculation made by Balkanski et al. This comparison has enabled us to determine the temperature of the silicon particles during laser irradiation.
Tunneling Measurements of Thin Film Y–Ba–Cu–O/Nb Junctions
Authors: Katoh Yujiro , Asano Hidefumi , Tanabe Keiichi , Michikami Osamu
Published: November 2005

A thin-film tunnel junction with a Y–Ba–Cu–O/Nb structure has been prepared using a strongly c-axis oriented poly-crystalline Y–Ba–Cu–O film deposited on a sapphire substrate. From the differential tunneling characteristics, the harmonic gap structure (Δ, 3Δ, 5Δ) for a Y–Ba–Cu–O compound could be observed.
V51Knight Shift in Fine V3Si Particles
Authors: Koyama Kuniyuki , Matsuo Susumu , Suzuki Yasuji , Ishimasa Tsutomu , Fukano Yasushige
Published: November 2005

The Knight shift of vanadium (KV) in fine V3Si particles was studied. The average diameter (d̄) ranged from 60 to 8000 A. The strong temperature dependence of theKVcharacteristic of high-TcA-15 compounds was weakened in the particles.KVat 77 K increased with a decrease in d̄. The above-mentioned trends were consistent with a broadening of the sharp peak in the electronic density of states around the Fermi energy in particles resulting from a perturbation of the surface.
Attachment-Enhanced Instability in CF4 Positive Columns
Authors: Ishikawa Itsuo , Suganomata Shinji , Matsumoto Michio
Published: November 2005

In a direct-current CF4 glow-discharge, two modes of waves were spontaneously excited in the pressure range 0.2–0.5 Torr and current range 4–10 mA. One was of the order of kHz and the other of the order of MHz. Both waves were observed to grow in the region E/P<46.5 V cm-1 Torr-1 in which electron attachment dominates.
The rf Response of Quasiparticle Injected Superconducting Weak Links
Authors: Kojima Kazuyoishi , Nara Shigetoshi , Hamanaka Koichi
Published: November 2005

The rf response of a new type of weak link (qasiparticle injected superconducting weak links) was investigated under irradiation of 13 GHz microwave. The samples comprised a lead alloy with a Pb/Nb injector junction. We observed the subharmonic current steps as well as the usual harmonic steps up to the 5th order. The number of steps depended on the indium concentration in the lead alloy. No current steps were observed for a pure lead sample; however, the existence of a phase coherence across the weak link was confirmed by means of the periodic response of a dc SQUID (superconducting quantum interference devices) to the external magnetic field.
Structure and Defects in Amorphous Si–O Films
Authors: Morimoto Akiharu , Noriyama Hidetaka , Shimizu Tatsuo
Published: November 2005

Amorphous Si–O films prepared by magnetron sputtering and glow discharge decomposition were investigated by infrared (IR) absorption, electron spin resonance and photoconductivity measurements. Amorphous Si–O films prepared by a glow discharge decomposition of SiH4+O2 gas mixture has a high photoconductivity with a wide optical gap, suggesting that hydrogenated amorphous Si–O films are not inferior to hydrogenated amorphous Si–C and Si–N as widegap materials. The compositional dependence of the peak position of the Si–O–Si stretching mode in the IR absorption spectrum for films prepared with various deposition conditions reveals that under a low substrate temperature Si and O atoms tend to be randomly mixed without O–O bonds while under a high substrate temperature they tend to be phaseseparated into Si and SiO2.
Determination of Surface Charge and Interface Trap Densities in Naturally Oxidized n-Type Si wafers Using ae Surface Photovoltages
Authors: Shimizu Hiromichi , Kinameri Kanji , Honma Noriaki , Munakata Chusuke
Published: November 2005

An ac surface photovoltage method was applied in order to estimate the fixed oxide charge density in naturally oxidized n-type Si wafers. Three n-type Si wafers (100-mm diameter, 540-µm thick and a resistivity of 1.1 mΩ·m) were used after forming 2.4-nm oxide layers on their surfaces as the result of an alkaline rinse treatment. The ac surface photovoltages in the frequency range of 1 Hz to 10 kHz were analyzed using the half-sided junction model previously reported. The photon energy of the probing beam was 2.23 eV. The surface potential, fixed oxide charge and interface trap densities were determined to be –0.38 V, –0.93 mC·m-2 and 5×1015m-2·eV-1, respectively.
Magneto-Optical Recording Characteristics of TbFeCo Media by Magnetic Field Modulation Method
Authors: Tanaka Fujio , Tanaka Shinsuke , Imamura Nobutake
Published: November 2005

To determine the most suitable composition for a magnetic field modulation recording, we investigated the static and dynamic recording (optical modulation method) characteristics of a TbFeCo film relative to an external magnetic field. It was made clear that the demagnetizing field is the chief determinant of the external magnetic field intensity and that a medium with a compensation temperature between room temperature and about 100°C is suitable for magnetic field modulation recording.
AC/N of 50 dB was obtained by modulating the external magnetic field at 500 kHz. An overwriting on the pre-signal was completely realized up to the frequency of 500 kHz.
Laser-Induced Fluorescence and Optical Reflection Spectra of Japanese Natural Dyes on Silk
Authors: Miyoshi Tadaki , Matsuda Yasunori
Published: November 2005

Fluorescence spectra under nitrogen-laser excitation were measured for silk cloth dyed with Japanese natural dyes. An identification of the dyes on silk was carried out using a laser-induced fluorescence (LIF) technique since dyed cloth has a characteristic fluorescence spectra. Moreover, it is possible to identify dyes on faded cloth and on cloth prepared by a combination dyeing using two kinds of dyes. The LIF technique can identify dyes on cloth which is difficult to identify using the reflection spectral method.
Calculation of Bond Lengths in InGaAsP Quaternary Alloy Semiconductor
Authors: Ichimura Masaya , Sasaki Akio
Published: November 2005

The bond lengths in an lnGaAsP quaternary alloy semiconductor were defermined using valence-force-field and continuum models. The bond lengths tend to preserve those in binary compounds. The length deviation from that of a binary compound is small if the bond-stretching force constant is large and/or the average bond-bending force constant is small. Theoretical results agree well with those obtained by experiments involving extended-X-ray-absorption fine-structure measurements. The validity of the Vegard law for a lattice constant is discussed and a slight discrepancy from the law is interpreted.
Selective MOCVD Growth of GaAs on Si Substrate with Superlattice Intermediate Layers
Authors: Soga Tetsuo , Sakai Shiro , Umeno Masayoshi , Hattori Shuzo
Published: November 2005

GaAs was grown on a Si substrate through a SiO2 mask using superlattice intermediate layers by MOCVD. Single and poly crystalline GaAs layers were grown on the Si substrate and on the mask, respectively. Ridge growth was observed at the substrate/mask interface. The relationship between the ridge growth properties (the shape and the height) and the growth conditions were made clear. The ridge growth rate increases exponentially with approaching the interface. The ridge shape was determined by the surface migration and the gradient in the gas phase concentration of the Ga active species. The ridge growth height of GaAs grown on GaAs was higher than that grown on Si. These results could be explained by taking account of the difference in the surface migration length of the Ga active species on GaAs and Si substrates.
A Pseudopotential Approach to Mixing Enthalpies of III-V Ternary Semiconductor Alloys
Authors: Ito Tomonori
Published: November 2005

The mixing enthalpies of III-III-V ternary semiconductor alloys are investigated using a pseudopotential perturbation approach. These enthalpies and the equilibrium lattice parameters are successfully calculated by accounting for local lattice distortion due to the random distribution of constituent III-group atoms. In addition, the bimodal distribution of anion-cation bond lengths is numerically obtained. The lattice parameters are found to be congruent with Vegard's law, and the mixing enthalpies qualitatively agree with previous experimental results. The dependence of the enthalpy on temperature is discussed by considering the dependence of strain energy. Thermodynamic stability for superlatticed compounds, disordered alloys, and phase mixtures is also discussed.
Theory of the Hollow Cathode Glow Discharge
Authors: Hashiguchi Seishiro , Hasikuni Mitugi
Published: November 2005

A theory of the hollow cathode glow discharge based on the two-temperature electron model is developed. The following two interdependent mechanisms are consistently taken into account: the creation of ions and excited atoms due to electron collisions in the discharge and the emission of secondary electrons on the cathode surface due to ions and ultraviolet photons. Trapped electrons in the hollow are also considered. Numerical calculations are made for helium gas in a cylindrical hollow cathode whose inner diameter and length are 10 and 32 mm, respectively, on the basis of a onedimensional steady state model. Voltage-current relations are obtained at gas pressures of 0.13, 0.27 and 0.40 kPa. Population densities of 64 excited atomic levels are determined as a function of the radial distance r as well as the densities of the ions and electrons.
Transport of Charge Carriers in Methylbixin Crystals: Photoconductivity Decay Measurements
Authors: Pal Prabir , Ghosh Dilip , Jain K. M. , Misra T. N.
Published: November 2005

The energy distribution of gap states in methylbixin crystallites has been investigated by photoconductivity decay measurements. The results show that the shallow states decrease exponentially with characteristic temperature T
c∼900 K at an applied field of 1.77×103 V/cm. T
c is independent of sample temperature but depends inversely on applied field. It is suggested that field effect on T
c may arise from the field effect on trapping rate.
Semiconductor Quantum-Well Structures for Optoelectronics–Recent Advances and Future Prospects–
Authors: Okamoto Hiroshi
Published: November 2005

Due to the quantum size effect, semiconductor quantum-well structure exhibits many unique material properties which can not be realized in conventional bulk crystals. These unique properties are very attractive for novel electronic and optoelectronic devices. This paper reviews studies on physical properties and application of quantum well structures for optoelectronics, and gives a future forecasting in the progress of this field.
Preparation and Properties of High-Quality a-Si Films with a Super Chamber : Separated Ultra-High Vacuum Reaction Chamber
Authors: Tsuda Shinya , Takahama Tsuyoshi , Isomura Masao , Tarui Hisaki , Nakashima Yukio , Hishikawa Yoshihiro , Nakamura Noboru , Matsuoka Tsugufumi , Nishiwaki Hidenori , Nakano Shoichi , Ohnishi Michitoshi , Kuwano Yukinori
Published: November 2005

A separated ultra-high vacuum (UHV) reaction chamber system, called the super chamber, has been newly developed. A background pressure of 10-9 Torr was obtained, and the impurity concentrations of oxygen, nitrogen and carbon in an a-Si film fabricated in the super chamber were 2×1018 cm-3, 1×1017 cm-3, and 2×1018 cm-3, respectively. The space charge density and the ESR spin density of the a-Si film were 5×1014 cm-3 and 2×1015 cm-3, respectively. These values were much lower than those for films fabricated in a conventional chamber. The ratio of the light-induced degradation in the photoconductivity of the a-Si film was also small compared with that of conventional a-Si films. A conversion efficiency of 11.7% was obtained for a glass/textured TCO/pin/Ag a-Si solar cell, whose i-layer was fabricated in the super chamber.
Effect of the Pretilt Angle and Temperature on the Multiplexing Limits of Dual Frequency Addressed TN–LC Cell
Authors: Jain S. C. , Balakrishnan K. S. , Chandra S.
Published: November 2005

We present below the results of (our studies on) dual frequency addressed twisted nematic liquid crystal (TN–LC) cells using recently developed Hoffmann La-Roche LC mixtures 3090 and 2851 which exhibit large positive and large negative dielectric anisotropy at low and high frequencies respectively. It is found that the surface alignment i.e., the tilt bias angle of LC molecules at the bounding surfaces and the temperature of the cell modify the electro-optic transmission characteristics significantly which in turn affect the multi-plexing limits. It is also shown that the cross over frequency `f
c' can be easily determined from the threshold voltage variation studies with frequency.
Stability as Regards Film Thickness, Homogeneity and Optical Properties of Thin a-Si:H Films
Authors: Myburg G. , Swanepoel R.
Published: November 2005

The instability, or other words, the spontaneous changes in the properties of the material (ageing) that occur in thin a-Si:H films in the atmosphere in the long term have been determined as a function of the preparation parameters–pressure, power, gas flow rate and substrate temperature. The repeated monitoring of the material properties of the original films required the use of a non-destructive technique. The chosen technique encompassed the obtaining of transmission spectra of the film-substrate configuration and from this the film thickness, the homogeneity parameter Δd and the optical properties, n(λ), α(λ) and E
0 were obtained. Of the four preparation parameters that were varied, substrate temperature played a dominant role as regards the material properties and stability of these films. Experimental results of a number of films that were deposited at temperatures equal to, or lower than room temperature consistantly underwent the following changes in the long term: increases in film thickness and E
0, and decreases in the values of the parameters Δd, n(λ) and α(λ). The effect of ageing, as seen from the results, was not only restricted to the surface, but appeared throughout the whole thickness of the film.
Structure Analysis of GaAs–AlAs Superlattice Grown by Molecular Beam Epitaxy
Authors: Osamura Kozo , Matsushima Wataru , Hiyamizu Satoshi , Muto Shunichi
Published: November 2005

General process analysing diffraction data has been considered in detail for the assessment of a superlattice structure. A method to determine the absolute value of the structure factor was proposed. This is important for comparisons with the model structure. Applying it to a GaAs–AlAs superlattice made for this special purpose, it was demonstrated that an apparent mixing of mutual group III elements occurs over two boundary layers. This structural feature was confirmed by a computer simulation and was attributed to the growth condition, by which the growth of mutual layers was strictly contorolled with an equi-thickness of one nm.
Fine Particles of Silicon. I. Crystal Growth of Spherical Particles of Si
Authors: Iijima Sumio
Published: November 2005

Fine crystals of Si having spherical shapes of less than 200 nm, as well as hybrid particles of Si and β-SiC were prepared by a gas evaporation method using an arc discharge as the heat source. Si particles always contain stacking faults and twins which are categorized as growth faults. All the planar faults in a particle occur in the same orientation (parallel to a [110] direction). The nature of these planar faults was examined in terms of crystal growth using an electron microscope. As a result, it has been concluded that these spherical Si particles are crystallized from liquid droplets which condense from Si vapors.
Fine Particles of Silicon. II. Decahedral Multiply-Twinned Particles
Authors: Iijima Sumio
Published: November 2005

Decahedral multiply-twinned particles of Si, 60–80 nm in size, prepared by a gas evaporation method are studied by a high resolution electron microscope. A mismatch arising in packing five tetrahedra is accommodated by deforming plastically one of the tetrahedra by introducing a small angle grain boundary. A core region of the particle, however, is deformed elastically. The structural details of the crystalline faults associated with the mismatch are described.
Plasma-Polymerized Films as Orientating Layers for Liquid Crystals
Authors: Watanabe Ryoichi , Nakano Toshiki , Satoh Taketoshi , Hatoh Hitoshi , Ohki Yoshimichi
Published: November 2005

Polymeric films were deposited onto a glass plate by RF glow-discharge polymerization. Monomer gases tried were ethylene, allylamine and tetrafluoroethylene. The effects of such surface properties as the contact angle, surface energy, and those measured by FT-IR or XPS on liquid crystal alignment were studied. It is shown that liquid crystal alignment can be controlled systematically by plasma copolymerization of different monomers or plasma treatment after polymerization which can vary surface properties continuously.
Synthesis of Superconducting Beryllium Thin Film by Ion-Beam Sputtering
Authors: Takei Koji , Okamoto Minoru , Nakamura Kiko , Maeda Yasushi
Published: November 2005

The superconductivity of beryllium films prepared by ion-beam-sputtering on substrates at room temperature originated in a metastable, highly disordered structure. The superconducting critical temperature (T
c) increased up to 7.0 K when the film thickness increases up to 20 nm. When crystal particles of normal hcp phase were grown in films with thicknesses of more than 40 nm, the T
c decreased. Incorporating oxygen into the film was helpful in making the film homogeneous by preventing hcp crystals from growing larger, but this tended to decrease T
c.
Absolute Density Measurement of OH Radicals in an Atmospheric Pressure Flame Using Time-Resolved Laser-Induced Fluorescence
Authors: Takubo Yoshitaka , Okamoto Tatsuki , Komine Norio , Yamamoto Manabu
Published: November 2005

We determined the absolute density of OH radicals in a propane-air flame using laser-induced fluorescence (LIF). To obtain the quantum efficiency of the fluorescence, the quenching lifetime of the A2Σ+ (υ'=0) level in the flame was measured with a time-correlated single-photon counting method using a picosecond dye laser. The efficiency of the fluorescence detection system was calibrated by a Rayleigh scattering measurement. The measured quenching rate, 5.6×108 s-1, was in agreement with a previous value deduced from the quenching cross sections at a high temperature. The number density obtained in the present work is consistent with the results of the absorption measurement.
Numerical Analysis of Group-V Element Transport and Incorporation at a Growing Surface in MOCVD Reactor
Authors: Sato Michio , Suzuki Motoyuki
Published: November 2005

The growth rate of epitaxial film by MOCVD is determined by the transport of group-III elements. However, group-V elements influence the electronic properties. It is often said about undoped GaAs that an increase of supplied arsine causes a p/n conductivity type conversion. A numerical model which considers the diffusion and decomposition of arsine is proposed. Using this model, the concentration of arsenic at a growing surface can be obtained as a function of the substrate temperature and the laminar fluid film thickness. Considering the properties of phosphine, the surface concentration of phosphorus can also be obtained. The phosphorus distribution coefficient of GaAsxP1-xcan be well described by using the estimated concentrations of arsenic and phosphorus with a simplified equilibrium of the surface reaction.
LMM and LVV Auger Electrons Induced by Ar+ Ion Impact on a Si Surface
Authors: Saiki Koichiro , Rittaporn Itti , Tanaka Shoji
Published: November 2005

The Auger electrons induced by keV Ar+ -ion impact on a Si surface were studied. The spectral dependences on the Auger electron emission angle, the incident Ar+ ion energy and the oxygen partial pressure during ion bombardment were investigated in detail. As a result, the difference in the energy dependence between atomic-like peaks and a bulk-like peak was clarified. The chemical shift of the bulk-like peak was observed. A buried peak was revealed by diminishing the large background of the bulk-like peak.
Development of ac Calorimetric Method for Thermal Diffusivity Measurement. II. : Sample Dimension Required for the Measurement
Authors: Hatta Ichiro , Kato Ryozo , Maesono Akikazu
Published: November 2005

In an ac light-irradiated method for thermal diffusivity measurements of rectangular plate-like samples partly shadowed by a mask, the required dimensions are considered. The contour length around the cross-section (given by the thickness times the width) should be so long that the sample has a proper amount of heat capacity; then, the external thermal relaxation time becomes sufficiently long so as not to dissipate ac thermal energy. The thickness, however, should be thin enough so as to obtain a uniform temperature across the sample during oscillations (as discussed in detail previously). For the sample length, the distance between the thermocouple and the sample boundary on which ac light is irradiated should be sufficiently long so that the thermal waves reflected at the boundary decay. However, there is no restriction on the other bourtdary shadowed by the mask, i.e., the thermocouple can be placed at the boundary.
Parameter Dependence of Ray Trajectory and Damping for the Ion Bernstein Wave in the TNT-A Tokamak
Authors: Shinohara Shunjiro , Naito Osamu , Ida Katsumi , Miyamoto Kenro
Published: November 2005

The dependence of ray trajectories and damping on various plasma parameters was studied using three-dimensional ray tracing for an ion Bernstein wave in the TNT-A tokamak. The condition for wave power absorption dominated by electron Landau damping was also estimated.