bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Light Exposure during Anodization on Photoluminescence of Porous Si
Authors: Asano Tanemasa , Higa Katsuya , Aoki Satoshi , Masayoshi Tonouchi Masayoshi Tonouchi , Tatsuro Miyasato Tatsuro Miyasato
Published: February 2005

Photoluminescence study has been carried out on porous Si which has been prepared from p-type Si wafers either by anodization under light illumination (photoanodization) or by anodization in the dark. It has been found that the photoanodization makes the luminescence peak wavelength shorter and the luminescence intensity stronger. As a result of these effects, visible red light luminescence has been reproducibly obtained. These effects have been found to be more pronounced when highly concentrated HF solutions are used for anodization. Scanning electron microscopy and Raman spectroscopy showed no distinct differences in microstructure or crystallinity between the photoanodized and in-dark anodized porous Si.
Feedback-Controlled Mode-Locking of Nd:Glass Laser Using GaAs
Authors: Kumazaki Shigeichi , Kubecek Vaclav , Takagi Yoshihiro , Reali Giancarlo C. , Keitaro Yoshihara Keitaro Yoshihara
Published: February 2005

The passive negative feedback-controlled mode-locking operation of a Nd: glass laser using a GaAs wafer as an intracavity limiter is reported. A long pulse train extended up to 700 ns with a pulse duration of less than 3 ps was generated. The single-pulse energy was 60 µJ, which is 6 times higher than those of Nd:YAP (YAlO3) and Nd:YAG lasers.
Electroluminescence in Perylene-and-Tetracene-Doped Anthracene Films
Authors: Okii Hironori , Ohba Hiroshi Hara
Published: February 2005

Electroluminescence (EL) in anthracene films simultaneously doped with perylene and tetracene was investigated under AC fields. The spectral distribution and intensity of EL can be controlled by changing the mole fractions of perylene and tetracene for anthracene. At the suitable mole fraction of dopants, the color of EL was varied from blue to green by changing the frequency from 50 Hz to 900 Hz. The radiant emittance of 0.5 mW/cm2 was obtained at the applied voltage of 100 V (50 Hz). The power conversion efficiency was approximately 0.03% (W/W).
Forces Acting on a Magnet Placed over a Superconducting Plane
Authors: Zhongjin Yang Zhongjin Yang
Published: February 2005

Based on the London theory, we have calculated the forces acting on a magnet placed above a superconductor. The results have been used to calculate (i) the forces acting on a spherical magnet over a superconducting plane; (ii) the forces acting on a ring-shape magnet above a superconducting plane; and (iii) the force between the tip of a magnetic force microscope (MFM) and a superconducting plane due to the diamagnetic response of the superconductor to the stray field of the tip.
Photoinduced Solubilization and Photocatalytic Properties of Poly(3-alkylthiophene) under Carbon Dioxide Atmosphere
Authors: Kawai Tsuyoshi , Takao Kuwabara Takao Kuwabara , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

Effects of light irradiation on poly(3-alkylthiophene) immersed in organic solvents have been studied under CO2 atmosphere. The insoluble part of poly(3-alkylthiophene) is solubilized in organic solvents by photoirradiation under CO2 atmosphere. Formation of carbonyl group in the solubilized poly(3-alkylthiophene) has been confirmed. The quenching effect of CO2 observed in the photoluminescence experiment of the poly(3-alkylthiophene) suggests electron injection from photoexcited poly(3-alkylthiophene) to CO2 molecules. Photocatalytic fixation of CO2 molecules resulting in formation of salicylic acid has also been achieved by a novel photocatalytic reaction using poly(3-alkylthiophene) as a photocatalyst under the existence of a substance such as phenol which reacts with CO2
\dot-.
High-Intensity Vacuum Ultraviolet Light Source in Windowless Photochemical Vapor Deposition Reactor and Its Application to a-Si:H Deposition
Authors: Kuroiwa Koichi , Yamazaki Hiroshi , Tsuchiya Satoshi , Koichi Kamisako Koichi Kamisako , Yasuo Tarui Yasuo Tarui
Published: February 2005

Optical emission characteristics of vacuum ultraviolet light which is effective in decomposing source gases used for deposition of hydrogenated amorphous silicon were investigated. The emission line from H atoms at 121.5 nm corresponds to the absorption peak of source gases of silicon hydrides. This emission line intensity increases markedly by mixing hydrogen with helium from 5 to 10% in concentration. The deposition rate of hydrogenated amorphous silicon films by windowless photochemical vapor deposition using this strong emission line at 121.5 nm is proportional to the emission intensity, which reaches as high as 270 Å/min.
X-Ray Magnetic Scattering in Fe-3 wt%Si
Authors: Sakurai Yoshiharu , Tsuda Osamu , Nomata Hiroshi , Kim Chan Wook , Watanabe Yasuhiro , Nanao Susumu , Iwazumi Toshiaki , Kawata Hiroshi , Ando Masami , Sakai Nobuhiko , Shiotani Nobuhiro
Published: February 2005

The intensity of interference scattering which originates in the product of charge and magnetic X-ray scattering amplitudes is successfully separated from the charge (Thomson) scattering intensity in the (220) reflection of Fe-3 wt%Si. Using intense elliptically polarized X-rays of about 1011 photons/s, sufficient counts can be accumulated within a short measuring time of about 6 minutes. The magnetic form factor determined from the interference scattering intensity agrees in sign and amplitude with the theoretical value.
Ion Energy Distribution of KrF Laser Ablation
Authors: Nishikawa Yukio , Yoshikazu Yoshida Yoshikazu Yoshida , Kunio Tanaka Kunio Tanaka
Published: February 2005

The KrF laser ablation of Al, Cu, Si, and SrTiO3 targets has been studied using an electrostatic deflection energy analyzer and a quadrupole mass filter. Beam like ions appear to accompany ablation. The average kinetic energies of Si+ and metal ions are about 45 eV and 60 eV, respectively. The energies of ions are ranked in the order of Si<metal (Al, Cu)<SrTiO3. The mean ion energy of Cu+ is not affected by the laser fluence range of 2-7.5 J/cm2.
In Situ Annealing of Melt-Grown ZnSe Crystals under Zn Partial Pressure
Authors: Kikuma Isao , Masatoshi Matsuo Masatoshi Matsuo , Toyokazu Komuro Toyokazu Komuro
Published: February 2005

Zinc selenide crystals are grown from the melt by a modified Bridgman method under argon pressure. A specific Zn partial pressure over the melt is maintained during growth by heating Zn in a reservoir. Grown crystals are annealed in situ in a crucible under Zn partial pressure. The annealed crystals exhibit n-type conduction. Electrical properties of the annealed crystals are affected by annealing temperature and Zn reservoir temperature. Low-resistivity crystals have a resistivity of 0.3 to 3 Ω·cm. The electron mobility is 260 to 560 cm2/V·s at room temperature. The electron mobility of the annealed crystals is also dependent on the Zn reservoir temperature during growth.
Upper Limits of Electron Beam Currents Focusable with High-Tc Bulk Superconductor Lenses (Supertrons)
Authors: Matsuzawa Hidenori , Kobayashi Hiroaki , Ohno Ken-ichi , Hosoda Takehiro , Chino Yukio , Hitoshi Miyagi Hitoshi Miyagi , Masatoshi Ishizuka Masatoshi Ishizuka
Published: February 2005

A tapered Bi-based high-T
c bulk superconductor tube was used as a lens (Supertron) for relativistic electron beams (REBs). When REBs (340 keV, ∼1 kA, ∼10-ns pulse width) were injected into a lens with a 3-mm-diameter exit, the REBs were quenched at ∼440 A. These results, in addition to those from previous papers, reveal possible upper limits of the electron beam currents to be focused; the compressed self-magnetic field of the electron beams should be less than ∼600 G at the inner surface of the lens exit. A model was proposed for the operation of Supertrons.
The Temperature Dependence of Photon-Gated Spectral Hole Burning for the Zn-Tetrabenzoporphin-Crotonic Acid/Phenoxy Resin
Authors: Zhang Zhonglin , Shi Luqing , Xie Jun , Horie Kazuyuki , Yao Shaoming , Zhang Manhua , Zhu Boshen
Published: February 2005

The temperature dependence properties of a new persistent spectral hole-burning system, Zn-tetrabenzoporphin-crotonic acid/phenoxy resin, are studied at temperatures from 20 to 100 K. Being annealed at different temperatures up to 80 K, the hole shape can partly recover at 20 K. The degree of hole recovery decreases as the annealing temperature is raised from 20 K. Two kinds of processes, reversible and irreversible, exist during the changing of the hole shape in the cycle annealing experiments.
Relationship between Rubbing Strength and Surface Anchoring of Nematic Liquid Crystal
Authors: Sato Yumiko , Kazutoshi Sato Kazutoshi Sato , Tatsuo Uchida Tatsuo Uchida
Published: February 2005

Rubbing is a simple but reliable method used to homogeneously align liquid crystal. It is widely used in the actual production of liquid crystal displays. However, this technology is mainly based on experience, and the relationship between rubbing strength and surface anchoring strength has not been clarified. Therefore, the authors have studied the relationship between the surface anchoring strength and the rubbing strength parameter L which is defined by the authors. Consequently, it has been determined that the anchoring strength is proportional to L, and that the memory effect of the surface orientation exists when there is weak anchoring strength.
Preparation of Highly Oriented Copper Films by Photo-Assisted Chemical Vapor Deposition Using β-Diketonate Complex
Authors: Zama Hideaki , Miyake Takayuki , Hattori Takeo , Shunri Oda Shunri Oda
Published: February 2005

We have obtained high-quality copper films by photo-assisted chemical vapor deposition using β-diketonate complex as a starting material. The thermal activation energy of the deposition rate with UV-irradiation is smaller than that without UV-irradiation, because of photo-assisted decomposition. Copper films prepared at a substrate temperature of 350°C with UV-irradiation are highly (111)-oriented with an electrical resistivity of 1.7 µΩ·cm, as low as the value of bulk copper. Surface morphology is smooth, because the growing surface has high nuclei density.
Dependence of Electron Cyclotron Resonance Plasma Characteristics on Introduced Microwave Conditions
Authors: Samukawa Seiji , Nakamura Tsuyoshi , Akihiko Ishitani Akihiko Ishitani
Published: February 2005

This study reveals the strong dependence of electron cyclotron resonance (ECR) plasma generation on the microwave conditions in the ECR plasma. When the introduced microwave frequency oscillates and has a large ripple, the ECR plasma around the ECR position vibrates. As a result, the half-value width of ion energy distributions around the ECR position is extended. Therefore, the microwave conditions cause plasma instability and disturb the ion flight paths to the substrate. The etching characteristics thus are degraded because of the low anisotropy and the deposition. In order to establish a stable discharge around the ECR position, the oscillation and ripple of this introduced microwave frequency must be accurately controlled.
Scanning Tunneling Microscopy Study of the 16-Structure Appearing on a Si(110) Surface
Authors: Yamamoto Youiti , Shin-ichi Kitamura Shin-ichi Kitamura , Masashi Iwatsuki Masashi Iwatsuki
Published: February 2005

High-resolution scanning tunneling microscopy (STM) was applied to observe the 16-structure appearing on a Si(110) surface. It was reaffirmed that the 16-structure coexisting with a facet structure was not found and could not be explained by the vicinal surface model. Bright and faint zigzag chains consisting of spheres, and the repetition of the upper and the lower layers with the height difference of 2.0 Å were observed. Based on the above result, a structure model was proposed.
Ultrashallow Junctions Formed by Excimer Laser Annealing
Authors: Tsukamoto Hironori , Yamamoto Hiroshi , Takashi Noguchi Takashi Noguchi , Toshiharu Suzuki Toshiharu Suzuki
Published: February 2005

A very shallow p+n junction was formed by BF2
+ ion implantation and excimer laser annealing (ELA) with single pulse irradiation. A thin amorphous layer formed by low-energy implantation was recrystallized effectively by single-pulse irradiation of an excimer laser. A shallow junction with little redistribution and sheet resistance as low as 100 Ω\Box was obtained. The junctions formed by ELA were compared with those formed by conventional rapid thermal annealing (RTA). It was confirmed that ELA with single-pulse irradiation can suppress unintentional diffusion of the implanted boron, and is more suitable for controlling the impurity profile of very shallow p+n junctions than RTA.
Indium Antimonide Layer Grown on Semi-insulating GaAs by Low-Pressure Metalorganic Chemical Vapor Deposition
Authors: Yasuo Iwamura Yasuo Iwamura , Naozo Watanabe Naozo Watanabe
Published: February 2005

An indium antimonide single crystal is epitaxially grown on a semi-insulating GaAs. Layer thickness is changed from 0.15 to 4.2 µm. The X-ray diffraction peak (400) position does not change much with thickness, while its width decreases with increasing thickness. Crystal orientation is (100) from the early stage, and its crystallinity improves with thickness. The 300 K mobility increases from 940 to 25000 cm2/V·s and carrier concentration decreases from 1.1×1018 to 8.0×1016 cm-3 with thickness. Their dependence on thickness and temperature indicates that lattice scattering, ionized impurity scattering and defect-related scattering all contribute to limiting the mobility.
Morphological Change in Deposited Films of Calcium Stearate by Thermal Treatment
Authors: Yase Kiyoshi , Yamanaka Mikihiro , Inaoka Kimio , Kiyotaka Sato Kiyotaka Sato , Masakazu Okada Masakazu Okada
Published: February 2005

After thin solid films of calcium stearate are formed on the substrates of KCl, mica and amorphous carbon film kept at 25°C in 1×10-6 Torr, they are annealed at 50-75°C for 10-60 min. As-deposited films consist of slender crystals 100-500 nm in length, in which molecules orient parallel to the surface. During annealing at 50°C, the growth hillocks grow to 1 µm or recrystallize to form plate crystals, in which molecules are arranged normal to the surface. With the substrates at 75°C, single crystals with a size of several µm can be obtained, in which molecules stand against the surface.
Transmission Electron Microscopic Analysis of Chemically Adsorbed Monolayers by Means of Replica Technique
Authors: Mino Norihisa , Tanaka Kazufumi Ogawa
Published: February 2005

Chemically adsorbed (CA) monolayers have been analyzed by means of the replica technique with a plasma polymerized film for transmission electron microscopy. On CA monolayers having different pretilt angles of the chemically adsorbed molecules which were controlled by mixing two surfactants, some differences in molecular density were clearly observed. After an acetylene derivative CA monolayer was polymerized, many lines, indicating conjugated double bonds, were observed in the monolayer. These results clearly support our previous reports. The technique is very useful for characterization of extremely small and thin samples.
Photoluminescence Study of CuInSe2 Thin Films Prepared by the Selenization Technique
Authors: Tanda Masayuki , Manaka Susumu , Marin Jorge R. Encinas , Kushiya Katsumi , Sano Hideki , Yamada Akira , Takahashi Makoto Konagai
Published: February 2005

CuInSe2 thin films were prepared by the selenization technique with solid- or vapor-phase selenium, and photoluminescence measurements were carried out to identify the energy levels associated with various defect structures. The possible origins of these defect states are discussed on the basis of the reported energy level diagram of single-crystal and thin-film CuInSe2. It is found that the photoluminescence measurement is sensitive to native defects and formation kinetics of CuInSe2 and useful in the optimization of the selenization process.
Uniform Electron Cyclotron Resonance Plasma Generation for Precise ULSI Patterning
Authors: Samukawa Seiji , Nakamura Tsuyoshi , Ishida Toshinori , Akihiko Ishitani Akihiko Ishitani
Published: February 2005

Microwave perturbation results in lower microwave absorption because of plasma vibrations and pulses in an electron cyclotron resonance (ECR) plasma. Moreover, the parabolic 875 G equimagnetic field and the nonuniform magnetic field gradient causes nonuniform microwave absorption. Then, magnetohydrodynamic (MHD) plasma instability is generated in the ECR plasma. Accurate control of magnetic field profiles and microwave conditions for uniform and efficient microwave absorption is essential to the achievement of stable ECR plasma generation for precise anisotropic etching.
High-Resolution Electron Microscopy Observation of Defects in 180 MeV Cu11+ Ion-Irradiated Bi2Sr2CaCu2O8 Crystals
Authors: Chenevier Bernard , Ikeda Shozo , Kumakura Hiroaki , Togano Kazumasa , Okayasu Satoru , Kazumata Yukio
Published: February 2005

Irradiation with 180 MeV Cu11+ ions, perpendicular to the surface of a 15-µm-thick Bi2Sr2CaCu2O8 layer, enhances the irreversibility fields and increases the values of the intragrain J
c of the superconducting material. Irradiation-induced structural damages have been observed by high-resolution electron microscopy. Crystal defects consist of long continuous cylindrical columns of highly damaged material that traverse the layer. Columns are parallel to the direction of the ion beam. Diameter values lie between 2 and 8 nm.
Reentrant Antiferroelectric Phase in 4-(1-Methylheptyloxycarbonyl) phenyl 4'-Octylbiphenyl-4-Carboxylate
Authors: Okabe Nobuhiro , Suzuki Yoshiichi , Kawamura Ichiro , Isozaki Tadaaki , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

The presence of three phases was found between SmA and the antiferroelectric SmCA
* phase in optically active (R)-4-(1-methylheptyloxycarbonyl)phenyl 4'-octylbiphenyl-4-carboxylate. Two of these phases were identified as SmCα
* and SmCγ
* by the miscibility test. The remaining phase between these was confirmed to be another antiferroelectric phase from dielectric measurement and conoscopic observation. Thus, antiferroelectric order appears at least three times: SmCα
*, the new antiferroelectric phase and SmCA
*. The new antiferroelectric phase is different from the SmCA
* phase in that it exhibits much lower stability against an electric field.
Crystal Structure of the High-Tc Phase (Tc∼111 K) in the Sb-Pb-Bi-Sr-Ca-Cu-O System
Authors: Gronsky Naoto Kijima
Published: February 2005

The crystal structure of the high-T
c phase (T
c∼111 K) in the Sb-Pb-Bi-Sr-Ca-Cu-O system has been determined using transmission electron microscopy. Both energy dispersive X-ray spectroscopy and high-resolution transmission electron microscopy indicate that Sb partially substitutes for Ca in the high-T
c phase (T
c∼111 K) of the Sb-Pb-Bi-Sr-Ca-Cu-O system, accompanied by extra oxygen atoms that compensate the oxygen deficiency in the central Cu-O layer sandwiched between adjacent Ca/Sb layers.
Numerical Achievement of Strong Localization of Light in Optical Waveguides with Aperiodic Grating
Authors: Takano Motohiro , Kousuke Yakubo Kousuke Yakubo , Tsuneyoshi Nakayama Tsuneyoshi Nakayama
Published: February 2005

It is demonstrated through numerical simulations that light is strongly localized in optical waveguides with an aperiodic grating. The proposed system is actually achievable by applying recent microfabrication techniques. Our results provide insight into the modeling and design of optical waveguides for observing the strong localization of light.
Nonlinear Optical Coefficient of AlAs Thin Film on GaAs Substrate
Authors: Ohashi Makoto , Kondo Takashi , Kumata Kiyoshi , Fukatsu Susumu , Kano Satoru S. , Shiraki Yasuhiro , Ryoichi Ito Ryoichi Ito
Published: February 2005

We report the first measurement of the nonlinear optical coefficient, d
14, at the fundamental wavelength of 1.06 µm, of AlAs grown by molecular beam epitaxy. The d coefficient is deduced from the intensities of second-harmonic waves reflected from an AlAs film grown on GaAs. Multiple reflections in the film and second-harmonic generation in the substrate are taken into account. The ratio |d
14(AlAs)/d
14(GaAs)| is found to be 0.23±0.06.
Field Ion-Scanning Tunneling Microscopy Study of C60 on the Si(100) Surface
Authors: Hashizume Tomihiro , Wang Xiang-Dong , Nishina Yuichiro , Shinohara Hisanori , Saito Yahachi , Young Kuk Young Kuk , Toshio Sakurai Toshio Sakurai
Published: February 2005

Field ion-scanning tunneling microscopy was employed to study the monolayer and multilayer adsorption behaviors of the C60 fullerene on the Si(100)2×1 surface. The C60 molecules reside stably in the trough at room temperature without rotation, encompassing the 8 neighbouring dimer-forming surface Si atoms with the nearest neighbour distance of 12 Å. For the first and second layers, only local ordering of square and quasi-hexagonal patterns was observed. The orderly Stranski-Krastanov mode island formation with the hexagonal packing was observed above the third layer with its lattice constant of 10.4 Å.
Low-Operation-Voltage Comb-Shaped Field Emitter Array
Authors: Itoh Junji , Tsuburaya Kazuhiko , Kanemaru Seigo , Watanabe Teruo , Itoh Shigeo
Published: February 2005

The dependence of emission properties on the structure of comb-shaped lateral field emitter arrays (FEAs) has been investigated. The present FEA consists of an array of rectangular emitter tips with 3 µm-wide edges and a gate self-aligned to the emitter. It was found from experimental results that the ratio of pitch (=p) to edge width (=a) of the array had a strong influence on the emission properties, and that p/a∼3 was an optimum ratio to lower the operation voltage. Under this condition, an emission current of 1.4 µA/tip was obtained at a gate voltage of 110 V.
Observation of Resistive and Magnetic Anomalies at 90-180 K in Artificially Layered Ca1-xSrxCuO2 Thin Films Grown by Laser Molecular Beam Epitaxy
Authors: Li Xiaomin , Tomoji Kawai Tomoji Kawai , Shichio Kawai Shichio Kawai
Published: February 2005

Thin films of Ca1-x
Sr
x
CuO2 have been grown by alternate deposition of Ca1-x
Sr
x
and CuO2 atomic layers in a low pressure NO2 ambient. X-ray diffraction and its intensity analysis have confirmed the formation of an infinite layer structure of Ca1-x
Sr
x
CuO2 with x=0.2-1.0. The lattice constant c and electrical conductivity increase systematically with increasing Sr/Ca ratio. Clear diamagnetic signals at 90 K and 120 K have been observed in SrCuO2 and Ca0.2Sr0.8CuO2 films, respectively. In the Ca0.2Sr0.8CuO2 films, the onset of a small diamagnetic signal and a resistivity drop are also observed around 180 K.
Molecular Beam Epitaxy Fabrication of SrTiO3 and Bi2Sr2CaCu2O8 Heterostructures Using a Novel Reflection High-Energy Electron Diffraction Monitoring Technique
Authors: Bodin Peter , Shigeki Sakai Shigeki Sakai , Yuji Kasai Yuji Kasai
Published: February 2005

SrTiO3 and Bi2Sr2CaCu2O8 layered structures were continuously grown by the molecular beam epitaxy technique with in situ reflection high-energy electron diffraction (RHEED). By using a new RHEED picture subtraction technique, we could display intensity changes due to only the topmost layer. This method allows us to sensitively detect roughness on the atomic scale and excess phase formation. The SrTiO3 layer could be grown by sequential shuttering as well as coevaporation. A heterostructure with a 60 Å Bi2Sr2CaCu2O8 film had a superconducting transition temperature of 53 K.
Theoretical Estimation of Leakage Current in II-VI Heterostructure Lasers
Authors: Ikuo Suemune Ikuo Suemune
Published: February 2005

II-VI heterostructures studied in terms of lasing properties up to now have been mostly common-anion or common-cation heterostructures, where the band offsets are localized either in the conduction band or in the valence band. This paper deals with a leakage current in this sort of p-i-n heterostructure under forward bias. It is shown that the leakage current does not necessarily depend on the band offset, but principally depends on the energy-gap difference between the active layer and the cladding layer. This result leads to the expectation that the above heterostructures with the nearly flat band structures either in the conduction band or in the valence band will be applicable as II-VI laser materials. Quantitative comparison between the radiative recombination current and the leakage current was also performed on the laser diode structure.
New Stable Icosahedral Quasicrystal in Mg-Pd-Al System
Authors: Koshikawa Naokiyo , Sakamoto Shinya , Keiichi Edagawa Keiichi Edagawa , Shin Takeuchi Shin Takeuchi
Published: February 2005

A thermodynamically stable icosahedral phase (I-phase) has been found to form in Mg-Pd-Al alloys in the compositional range 13 to 15 at%Pd and 42 to 44 at%Al. The X-ray diffraction measurements have shown that the I-phase is of the Frank-Kasper type (FK-type), as in Al-Li-Cu and Mg-Ga-Zn alloys. The stability of the I-phase has been confirmed by the result that it shows no transformation by annealing for 40 h at temperatures just below the melting point. The electrons per atom ratio (e/a) for the Mg-Pd-Al I-phase is ∼2.15, which is nearly equal to those for other stable FK-type I-phases. This result suggests that the energy-band structure plays a dominant role in the formation of I-phases.
Stable One-Dimensional Quasi Crystal in a Al-Cu-Fe-Mn System
Authors: Tsai An Pang , Sato Akira , Yamamoto Akiji , Akihisa Inoue Akihisa Inoue , Tsuyoshi Masumoto Tsuyoshi Masumoto
Published: February 2005

A stable one-dimensional quasi crystal was formed in a fully annealed Al65Cu20Fe10Mn5. It was confirmed by stereographic electron diffraction analysis that the one-dimensional quasi crystal has a modified decagonal structure with 6-layer periodicity along the original c axis and 8-layer periodicity in the P direction. Microscopic observation reveals a linking columnar morphology with planar facets around the columns. The columnar direction is identified to coincide with the pseudotenfold(c) axis.
Spectral and Spatial Behavior of Raman Scattering and Photoluminescence from Porous Silicon
Authors: Inoue Koichi , Matsuda Osamu , Maehashi Kenzo , Murase Hisao Nakashima
Published: February 2005

Depth profiles of Raman scattering and the photoluminescence (PL) properties of anodized porous Si have been studied by micro-measurement techniques. In Raman spectra a remarkable low-energy shift and broadening of the optical phonon line are observed as compared with the bulk Si phonon line basically owing to the phonon confinement. In the depth profiles the PL shows blueshift correlating with the low-energy shift of the Raman peak as the measured point approaches the surface. The redshift of the PL peak has been observed with the low-energy excitation in normal-incidence experiments. It is concluded that the structural depth inhomogeneity strongly affects the optical properties of porous Si.
Photoluminescence of Cd-Doped CuAlS2
Authors: Aksenov Igor , Yasuda Takashi , Kai Tetsuya , Nishikawa Nobuyuki , Tsuyoshi Ohgoh Tsuyoshi Ohgoh , Katsuaki Sato Katsuaki Sato
Published: February 2005

The observation of the intense yellow-green photoluminescence band peaked at 565 nm from CuAlS2 crystals, grown by the chemical vapour transport technique and subsequently doped with Cd, is reported. The emission is interpreted as originating from donor-acceptor pair recombination, involving deep levels, formed by the Cd-introduced defects.
Gain Characteristics of Erbium-Doped Fiber Amplifiers with High Erbium Concentration
Authors: Yasuo Kimura Yasuo Kimura , Masataka Nakazawa Masataka Nakazawa
Published: February 2005

The gain characteristics of erbium-doped fiber amplifiers (EDFAs) with erbium
concentrations as high as 8900 ppm have been investigated in detail with 0.98 µm and 1.48 µm pumping schemes. Although the emission cross section at 1.532 µm is 24% less than that with low erbium concentration as a result of concentration quenching, a gain as high as 24 dB was obtained with a 50 cm long fiber at a 0.98 µm pump power of 60 mW. An output power of +8 dBm was also obtained for a pump power of 60 mW at pump wavelengths of both 0.98 µm and 1.48 µm. It is concluded that the 0.98 µm pumping scheme is better than that of 1.48 µm for high concentration silica-based EDFAs.
Ozone Generation of Bipolar-Type Ceramic Ozonizer Module with Semiconductor Ceramic Discharge Electrode
Authors: Watanabe Toshiya , Yuji Aso Yuji Aso , Chiaki Nakayama Chiaki Nakayama
Published: February 2005

A bipolar type ozonizer of small size and long life is developed for use in the living environment. The ozonizer is composed of an alumina substrate with tungsten inner electrodes, and a discharge electrode made of TiO2- or Cr2O3-added alumina ceramics. Effects of resistivity of the ceramic discharge electrode on ozone generation and discharge voltage are evaluated. Based on the differences in the dependency of the resistivity on discharge ignition voltage between monopolar-type and bipolar-type ozonizers, advantages of bipolar ozonizers over monopolar type in practical applications are discussed.
Ion Transport in Concentrated Electrolyte Solutions
Authors: Dodo Taro , Toshi-Aki Nakagawa Toshi-Aki Nakagawa , Eiji Nonaka Eiji Nonaka
Published: February 2005

The electrical conductivity and viscosity of concentrated solutions above several moles per liter are investigated by treating electrolyte solution as high-density plasma (strongly coupled plasma), where the Coulomb interaction energy is larger than the thermal kinetic energy. The normalized nondimensional conductivity, which is the electrical conductivity divided by the ion concentration and scaling parameters, is expressed as a function of the coupling constant Γ≡(Coulomb energy)/(thermal energy)=((ze)2/εa)/kT, where ε is the dielectric constant, a is the interionic distance and k is the Boltzmann constant. The normalized nondimensional conductivities of molten alkali halides except for fluoride at various temperatures lie on a single curve as a function of the Coulomb coupling parameter Γ. These molten salts can be good models for high-density plasma in spite of their different ion sizes.
Novel Method of Modulation Spectroscopy for Heterostructures: Electro-Photoreflectance
Authors: Yamaguchi Masahito , Kubo Hitoshi , Taniguchi Kenji , Fujii Chihiro Hamaguchi
Published: February 2005

A new modulation spectroscopy for studying the optical transition energies of layered electronic materials is presented. The method is based on a superposition of the modulation field produced by illumination of a laser and the field produced by external voltage to maintain a constant surface field unchanged, giving rise to reflectance signals due to the buried layer. A comparison of the present method with conventional electroreflectance and photoreflectance methods reveals that the present method (called electro-photoreflectance) picks out the reflectance signals from the buried layers but not those from the front surface.
Electron Microscope Study of Decagonal Quasicrystals of Al70Ni15Fe15
Authors: Tsuda Kenji , Saito Masakazu , Terauchi Masami , Tanaka Michiyoshi , Tsai An Pang , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

Decagonal quasicrystals of an Al70Ni15Fe15 alloy were investigated by transmission electron microscopy. Dark-field image studies revealed that there exist inversion domains and the domain boundaries accompany the antiphase shift of c/2. High-resolution image studies revealed that specific pentagonal atom clusters exist and that all the clusters in a domain have the same sense of polarity and those in the neighboring domains have the opposite sense. A preliminary structural model for explaining the high-resolution image was generated by the section method.
Preparation and Characteristics of Capacitors with Organic Conductor as Solid Electrolyte by Ion-Assisted Evaporation
Authors: Kyokane Jun , Isa Isao , Yoshino Katsumi
Published: February 2005

Ion-beam-assisted deposition of organic materials has been proposed for obtaining high-quality thin films. As an example, organic thin films have been prepared by means of evaporation of 7,7,8,8-tetracyanoquinodimethane (TCNQ) complex on porous oxide Al plates under ion beam irradiation. A Solid electrolytic capacitor with a large capacitance and a good frequency response can be fabricated utilizing thin films obtained with this method as solid electrolyte.
Restructuring of the Reconstructed Si(111)7×7 Surface by Metal(Au, Ag) Deposition
Authors: Akihide Shibata Akihide Shibata , Kunio Takayanagi Kunio Takayanagi
Published: February 2005

Restructuring epitaxy of Au and Ag on the Si(111)7×7 reconstructed surface has been studied by scanning tunneling microscopy (STM), which proceeds with hole-island pair creation of the √3×√3 structure on the 7×7 surface. The hole-island pair, which is a pair of areas with the √3×√3 structure lying higher and lower than the 7×7 surface, is found to be due to the change in the number density of the Si atoms in the reconstructed Si surface layer. The ratio of the area of the hole to that of the island is almost same from one pair to the other. The Si atoms of the reconstructed surface layer of the island are supposed to be supplied from the surface layer forming the hole. Provided that the number density of the Si atoms in the 7×7 surface is 2.08 ML according to the dimer adatom stacking-fault (DAS) model, the result indicates that the number density of Si atoms in both √3×√3 structure is 1 ML and that almost all the Si atoms which included in the initial 7×7 surface are preserved to create the hole-island pair. Such restructuring epitaxy results in roughness of the surface even if the initial surface is atomically flat.
Electronic Structures of Layered C60 and C70 on Si(100) Surface
Authors: Kawazoe Yoshiyuki , Kamiyama Hiroshi , Yutaka Maruyama Yutaka Maruyama , Kaoru Ohno Kaoru Ohno
Published: February 2005

Two-dimensional band structure calculation is carried out for the c(4×3) C60 and perfect triangular C70 lattices by using a mixed-basis approach in which wave functions are expanded with not only plane waves but also the 1s and 2p atomic orbitals of carbon atoms. The effect of the Si(100) substrate is taken into account by simply assuming a charge transfer from Si dimers and a positive charge back-ground. Wave functions of excess charge on these microclusters are analyzed, and the resulting partial charge distributions explain the electron cloud images observed recently with scanning tunneling microscopy (STM).
ESR Study of the Paramagnetic Behavior of the Conduction Electrons in Czochralski-Grown Silicon Crystals
Authors: Noda Hiroyuki , Oikawa Kazuo , Hitoshi Kamada Hitoshi Kamada
Published: February 2005

An electron spin resonance (ESR) method has been used to examine the paramagnetic behavior of the conduction electrons from phosphorus and of those from thermal donor (TD) in Czochralski-grown (CZ) silicon crystals at 113-173 K. The paramagnetic behavior of the conduction electrons from TD differed from that of electrons from phosphorus. This difference is discussed in terms of the difference in the relaxation times and the scatter of the conduction electrons by the ionized TD.
A Unified 3-D Mobility Model for the Simulation of Submicron MOS Devices
Authors: Yang Jiuun-Jer , Chung Steve Shao-Shiun , Chien-Hwa Chang Chien-Hwa Chang , Giahn-Horng Lee Giahn-Horng Lee
Published: February 2005

A calibrated and physically based mobility model is developed for three-dimensional simulation of submicron metal-oxide-semiconductor (MOS) devices, in which the inversion layer mobility is emphasized. This inversion layer mobility can be generalized into a local form, i.e., expressed as functions of the local electric field at each grid point, so that it is well suited for device simulation. The resulting 3-D mobility model accurately characterizes the significant physical scattering effects including the Coulomb screening effect, quantum channel broadening effect, surface roughness scattering, structure-induced lateral surface scattering and velocity saturation limited effects. Results show that this new model can be incorporated into device simulators for accurately predicting drain currents of submicron LDD MOS devices. Moreover, the results compare more favorably with the experimental data than do those for other reported models.
Thermal Extraction Behavior of He and D from He+-Implanted Yttrium Iron Garnet Annealed in D2
Authors: Hirotsune Akemi , Masuda Kimihiko , Kikuchi Tadashi , Furuya Keiichi , Uematsu Kenichi , Imura Ryo
Published: February 2005

Thermal extraction behavior of He and D from He+-implanted yttrium iron garnet (Y3Fe5O12 or YIG) thin films annealed in D2 and activation energies of He and D in each trapping state have been investigated by means of a thermal desorption mass spectrometric (TDS) technique in order to clarify the effect of hydrogen on the effective anisotropy field change induced by ion implantation followed by D2 annealing. Four trapping states of He in He+-implanted YIG were observed when it was annealed under T
a=320°C at a constant pressure of 760 Torr. The residual He atoms shifted to stabler states when it was annealed at above T
a=350°C. Two trapping states of diffused D atoms which were extracted as a form of D2O were observed for two kinds of YIG samples annealed in D2 atmosphere. The relationship between effective anisotropy field change induced by ion implantation and the thermal extraction behavior of He and D was discussed against the annealing temperature.
Radiation Torque Exerted on a Rotating Sphere in a Focused Gaussian Laser Beam: First-Order Correction in Angular Velocities
Authors: Lee Soo Chang
Published: February 2005

We investigate the radiation torque exerted on a rotating dielectric sphere in a focused Gaussian beam. In the (inertial) laboratory frame we solve the relativistic scattering problem for the Gaussian beam incident on a rotating sphere by including correction terms of up to first-order in angular velocities. We then derive the analytical formulas of the radiation torque within the framework of a scattering theory and discuss the derived results in comparison with our earlier works for a stationary sphere. Numerical results show that the ratio of the first-order correction to the zeroth-order torque is about 0.2×10-2 at the highest rotational frequency.
A Novel Super Resolution Technique for High-Density Optical Data Storage using Mode Interference in Channel Waveguides
Authors: Ooki Hiroshi , Arimoto Rieko , Yutaka Iwasaki Yutaka Iwasaki , Jun Iwasaki Jun Iwasaki
Published: February 2005

A novel super-resolution system using a waveguide device is proposed and theoretical considerations are given. This system is capable of raising the storage density of optical discs considerably. The detected signal is calculated using scalar diffraction theory and the three-dimensional beam propagation method. The structure of the disc is substantially the same as that of conventional compact discs, which is the outstanding advantage of this method.
Carrier Transport Across Metal-Polymer Barriers
Authors: Assadi Azar , Fu Ying , Magnus Willander Magnus Willander , Christer Svensson Christer Svensson
Published: February 2005

The electrical transport properties of aluminium-poly(3-octylthiophene) are investigated using current-voltage (I-V) measurement. The theoretical analysis of the I-V spectra measured at various temperatures shows that at relatively high forward voltage the forward current is dominated by the diffusion of charge carriers, while at lower forward bias and low temperature it is the tunneling current that dominates.
The Backside Pulse Doped Channel Heterostructure Field-Effect Transistor: Design, DC, and RF Performance
Authors: Juergen Dickmann Juergen Dickmann
Published: February 2005

We report about a theoretical and experimental study of AlGaAs/InGaAs modulation doped field-effect transistors (MODFETs) having doped channels. On the basis of self consistent calculations we suggest design rules of where to introduce the channel doping into the channel to obtain high speed devices with high saturation currents and reasonable low noise performance. For a 0.35 µm gate length backside pulse doped channel device (BSPDC-HFET) with 120 µm gate width a maximum transconductance of 625 mS/mm and a maximum saturation current at V
GS=+0.8 V of 720 mA/mm have been measured. The cut-off frequencies are f
T=80 GHz, f
max=195 GHz. At 18 GHz a minimum noise figure of N
F=1.1 dB with 17 dB associated gain were measured.
Scanning Tunneling Microscope Observation of a Polar Liquid Crystal and Its Computer Simulation*1
Authors: Matsushige Kazumi , Taki Seiji , Okabe Hirotaka , Takebayashi Yasuo , Hayashi Kouichi , Yoshida Yuji , Horiuchi Toshihisa , Hara Kazuhiro , Takehara Kenji , Isomura Kazuaki , Taniguchi Hiroshi
Published: February 2005

The scanning tunneling microscope (STM) constructed in the laboratory was utilized to observe the molecular arrangement of a new type of liquid crystalline molecule, 5-(p-dodecyloxyphenyl)pyrazine-2-carbonitrile (DOPPC), which has large dipole moments along the molecular axis. The DOPPC molecules adsorbed on a graphite substrate showed several different STM images with regular two-dimensional molecular arrays. They revealed a novel interdigitated double-row structure, differing from the single-row and the double-row structures proposed for the STM images of cyanobiphenyl liquid crystals. Moreover, a computer calculation was conducted based on electrostatic multipole-multipole interaction and simulated the most energetically preferable molecular arrangement, which agreed well with the observed STM image.
Intermediate Amorphous Layer Formation Mechanism at the Interface of Epitaxial CeO2 Layers and Si Substrates
Authors: Inoue Tomoyasu , Ohsuna Tetsu , Obara Yasuhiro , Yamamoto Yasuhiro , Satoh Masataka , Sakurai Yoshinobu
Published: February 2005

The formation mechanism of an intermediate amorphous
layer between epitaxially grown CeO2 layers and silicon substrates
is studied using cross-sectional transmission electron microscopy
and Auger electron spectroscopy.
The intermediate amorphous layer thickness increases after annealing
at 800°C in air, whereas it decreases somewhat after annealing
in an ultrahigh vacuum.
Auger in-depth analysis verifies that the intermediate amorphous layer
is silicon dioxide.
The intermediate oxide growth of the CeO2/Si structures
due to intentional oxidation at 700∼900°C
in a dry oxygen ambient
is analyzed and the results indicate that the oxidation
proceeds in an intermediate step between
reaction limited and diffusion limited processes.
The intermediate amorphous layer formation mechanism is concluded to
be oxygen diffusion through CeO2 layers
and successive oxidation of silicon at the interface.
Influence of Pulse Width on CdS Film Prepared by YAG Laser Ablation
Authors: Keitoku Hiromichi Ezumi
Published: February 2005

CdS films were deposited on glass substrates using two kinds of YAG lasers: one with a long pulse width of τ=100 µs and one with a short pulse width of τ=15 ns. Scanning electron microscopy observation and X-ray diffraction patterns showed that the film formed by the long pulse laser with a low energy density has a smooth surface and highly oriented texture. Resistivity is distributed in a wide range: 100-2000 Ω·cm and 10-100 Ω·cm for the films formed by long and short pulse lasers, respectively. Measurement of optical transmission spectra suggests the existence of an impurity level in the low resistivity film. Streak image of the plume obtained using an image converter camera showed that the average velocity of ablated luminous particles is about 5×104 cm/s for long pulse laser ablation and (3-9)×105 cm/s for the short one.
Thermal Desorption and Infrared Studies of Plasma-Enhanced Chemical Vapor Deposited SiO Films with Tetraethylorthosilicate
Authors: Hirashita Norio , Shunichi Tokitoh Shunichi Tokitoh , Hidetsugu Uchida Hidetsugu Uchida
Published: February 2005

Thermal desorption and Fourier transform infrared spectroscopies were used to study plasma-enhanced chemical vapor deposited SiO films from tetraethylorthosilicate. Significant water desorption and concomitant structural changes were observed for the films during subsequent heat treatments between 100 and 700°C. The films exhibited three distinct water desorption states. The desorption temperatures were approximately 100-200°C for the first state, 150-300°C for the second state, and 350-650°C for the third state. Air exposure experiments revealed that the first and second states resulted from absorbed water and the third state from constitution water. The first and second desorption states were confirmed to originate from liquid like water and water molecules hydrogen-bonded to Si-OH bonds at macropore sites in the films, respectively. The third desorption state was found to result from Si-OH bonds formed during the film growth. This desorption of constitution water was considered to be accompanied by a microstructural change of the films.
Synthesis of Diamond in Combustion Flame under Low Pressures
Authors: Komaki Kunio , Yanagisawa Masaaki , Hirose Isamu Yamamoto
Published: February 2005

The oxygen-acetylene combustion flame method has been investigated as to low pressure, gas ratio and substrate temperature effects, and flame emission spectral analysis. Non-diffusion of oxygen from ambient atmosphere enhanced expansion of the area and the amount of deposited diamond. H and OH radical emission have not been observed on combustion flames in a chamber. The reactions relating C2 and CH radicals have been revealed to have important roles in diamond synthesis.
Plasma Generation by Resonant-Cavity Microwave Discharge and Its Applications for Material Processing
Authors: Tahara Hirokazu , Minami Ken-ichiro , Yasui Toshiaki , Onoe Ken-ichi , Yasuji Tsubakishita Yasuji Tsubakishita , Takao Yoshikawa Takao Yoshikawa
Published: February 2005

A 2.45-GHz-microwave plasma source with a resonant cavity was studied for material processing under medium to atmospheric pressures. Stable plasmas, with electron temperature and density of 1 to 5 eV and beyond the plasma cutoff density, respectively, were efficiently sustained in an ambient pressure of 10-2-10 kPa with hydrogen, helium, nitrogen, argon and a mixture of H2+2H2 (vol. rate). The operational characteristics of coupling efficiency and cavity length depended on gas species. From electric fields measured on the cavity inner wall, the electromagnetic field pattern of TM011 resonance mode was expected to be excited in the cavity over a wide range of operational conditions. In addition, operation of a plasmajet generator, into which the plasma source was modified, diamond film synthesis and surface modification due to atomic oxygen were demonstrated.
Measurement of Knife-Edge Responses of a Schwarzschild X-Ray Objective
Authors: Iketaki Yoshinori , Horikawa Yoshiaki , Nagai Koumei , Mochimaru Shouichirou , Ohta Yoshinori , Kamijou Haruo , Shibuya Masaaki
Published: February 2005

The spatial resolution of a Schwarzschild objective was evaluated at the wavelength of 135 Å by means of an apparatus constructed using the knife-edge method which is suitable to the measurement of higher resolution. The knife-edge response of the objective was measured with the apparatus. Then the results were compared with the theoretical responses calculated using ray tracing. It is found that the measured responses of the objective are almost the same as the theoretical ones. We conclude that the objective has the spatial resolution of 0.2 µm.
Complex Calorimeter with AC- and Relaxation-Mode Operation
Authors: Ema Kenji , Uematsu Takashi , Atsushi Sugata Atsushi Sugata , Haruhiko Yao Haruhiko Yao
Published: February 2005

A complex calorimeter has been developed. This calorimeter, which can be operated both in the ac mode and the relaxation mode using the same sample cell and the same apparatus settings, uses only a small amount (30-50 mg) of sample. An application to measurements in the vicinity of the antiferroelectric phase transitions in the liquid crystal MHPOBC(4-(1-methylheptyloxycarbonyl)-phenyl 4'-octyloxybiphenyl-4-carboxylate) is demonstrated. It is shown that the present calorimeter, when operated in the relaxation mode, enables detection of the latent heat with a resolution of 0.002 J/g.