bluuebunny/crossref_metadata_2025 huggingface dataset:
Difference in Doping Effects of C60 and C70 in Poly(3-hexylthiophene)
Authors: Yoshino Katsumi , Yin Xiao Hong , Zakhidov Shigenori Morita
Published: February 2005

C60 (Buckminsterfullerene) can be an acceptor dopant for poly(3-hexylthiophene), inducing marked changes in optical absorption and photoluminescence due to charge transfer from polymer to C60 upon doping. Electrical conductivity also changes to some extent upon C60 doping. In contrast, C70 is not effective as a strong dopant in poly(3-hexylthiophene). That is, the absorption spectrum does not change markedly upon C70 doping and the change in electrical conductivity is also found to be much smaller than in the case of C60 doping. However, photo-luminescence is markedly quenched upon C70 doping, just as in the case of C60 doping. These results are discussed by accounting for the difference in electronic energy states of both C60 and C70 relative to that of poly(3-hexylthiophene). The important role of photoinduced charge transfer for quenching of photoluminescence is discussed and C70 is proposed to be a good sensitizer for photoconductivity of poly(3-alkylthiophene).
Structural Properties of Amorphous Carbon Nitride Films Prepared by Reactive RF-Magnetron Sputtering
Authors: Nakayama Noriaki , Tsuchiya Yasuaki , Tamada Satoru , Kosuge Kouji , Nagata Shinji , Takahiro Katsumi , Yamaguchi Sadae
Published: February 2005

Highly nitrogenated amorphous carbon films have been prepared by reactive rf-magnetron sputtering using pure N2 or Ar/N2 mixed gases. The nitrogen content measured by Rutherford backscattering spectrometry was 40 at% for pure N2 gas and 35 at% for Ar75%-N225% mixed gas. Oxygen atoms of about 7 at% were also detected. Infrared spectra showed a broad absorption band in the range from 1200 to 1600 cm-1 assigned to the N atoms incorporated in the bonding network of amorphous carbon. They showed an absorption band near 2200 cm-1 assigned to the C≡N or N=C=O bond, but no trace of the N-H or C-H bond was seen.
Strong Circular Dichroism in Photoelectron Diffraction from Nonchiral, Nonmagnetic Material–Direct Observation of Rotational Motion of Electrons
Authors: Daimon Hiroshi , Nakatani Takeshi , Imada Shin , Suga Shigemasa , Kagoshima Yasushi , Miyahara Tsuneaki
Published: February 2005

Strong circular dichroism is found in 2-dimensional angular distribution patterns of the Si 2p photoelectrons from the Si(001) surface, which has no chirality and magnetism. The forward focusing peaks in the pattern rotate clockwise or counterclockwise when the helicity of the incident circularly polarized light is reversed. These rotations of the pattern are explained by rotational motion of photoelectrons around the nuclei. This is the first direct observation of the rotational motion of the electrons and clarifies the correspondence between the classical and the quantum mechanical ideas of angular momentum.
Utilization of Non-Pseudomorphic Growth to Realize Tensile Strain on GaAs Substrates
Authors: Chan Yuen-Chuen , Tetsurou Morimoto Tetsurou Morimoto , Kunio Tada Kunio Tada
Published: February 2005

A novel structure consisting of a thick non-pseudomorphic InAlAs grid layer and InGaAs-GaAs strained-layer superlattice dislocation filter is proposed for realizing tensile strain on GaAs substrates. The structure is examined and characterized by photoluminescence, Nomarski etch-pit microscopy and double crystal X-ray diffraction and found to be effective in the incorporation of tensile strain in devices grown on the GaAs substrate.
Optimum Design Method of Optoelectronic Devices in Consideration of Errors of Structural Parameters
Authors: Hara Kunihiko , Takashi Iwamoto Takashi Iwamoto , Kazuo Kyuma Kazuo Kyuma
Published: February 2005

Recently, we proposed an optimum design method of optoelectronic devices based on simulated annealing. In this letter, errors of the structural parameters, which are essential in the fabrication of large scale arrays, are newly taken into consideration. To obtain a structure with greater tolerance, we develop two design methods: with the neighborhood cost reflecting tolerance (neighborhood cost method) and with annealing to a finite temperature (finite-temperature annealing method). These are successfully demonstrated by the optimum design of AlGaAs/GaAs pnpn optical switches.
Photoresist-Assisted Release of Movable Microstructures
Authors: Kobayashi Dai , Chang-Jin Kim Chang-Jin Kim , Hiroyuki Fujita Hiroyuki Fujita
Published: February 2005

A simple but efficient technique to avoid the post-release adhesion problem of movable surface-micromachined structures is reported. A grid pattern of photoresist reinforces microstructures during wet etching of the underlying sacrificial layer followed by rinsing and drying. The photoresist is eventually removed by the dry process. This technique requires minimal modification to the original fabrication process while rendering batch process capability for the release of microstructures. The technique was employed to fabricate comb-drive microactuators and demonstrated considerable improvement in yield.
Effects of Rolling Process on the Microstructural and Superconducting Properties of Bi-Pb-Sr-Ca-Cu-O Tape
Authors: Kao Chin-Hai , Lee Liang-Chih , Chiu Yi-Da , Lei Tien-Shou , Maw-Kuen Wu Maw-Kuen Wu
Published: February 2005

The effects of rolling process on the microstructural and superconducting properties of Ag-sheathed Bi-Pb-Sr-Ca-Cu-O superconducting tapes were investigated. The decrease of the reduction of thickness per pass during cold rolling is very useful in inhibiting the formation of cracks and improving the critical current density of Ag-sheathed BPSCCO tapes. On the other hand, the deformation texture resulting from cold rolling seems dependent on the thickness, but not affected by the amount of deformation in thickness per pass.
Photopumped Blue Laser Action in ZnSe-ZnMnSSe Double Heterostructure Grown by Molecular Beam Epitaxy
Authors: Karasawa Takeshi , Kazuhiro Ohkawa Kazuhiro Ohkawa , Tsuneo Mitsuyu Tsuneo Mitsuyu
Published: February 2005

ZnSe-ZnMnSSe double hetero (DH) structure was grown on (100) GaAs by molecular beam epitaxy. The X-ray diffraction profile revealed that the epilayers were lattice-matched to the substrate. The photoluminescence spectrum at 77 K was dominated by near-edge emission at 443 nm. Pulsed laser operation at 447 nm was observed in the DH structure sample placed in liquid nitrogen, for the first time, by optical pumping using pulsed 337 nm output of a nitrogen laser.
Dependence of Minority-Carrier Recombination Lifetime on Surface Microroughness in Silicon Wafers
Authors: Hiroshi Daio Hiroshi Daio , Fumio Shimura Fumio Shimura
Published: February 2005

The influence of silicon surface microroughness on the minority-carrier recombination life-time has been studied with a laser/microwave photoconductance technique. By means of an algorithm for separating the surface and bulk components, it has been shown that the microroughness considerably affects the surface recombination velocity, in turn the lifetime, of silicon wafers at elevated temperatures. It is found that the smoother results in the higher liletime.
Second-Order Optical Nonlinearities in Disazo Dyes Having a Perfluoroalkylsulfonyl Group
Authors: Hirota Kazuo , Hosoda Masahiro , Joglekar Bharati , Matsui Masaki , Muramatsu Hiroshige
Published: February 2005

The second-order nonlinear optical coefficients d
33 (-2ω: ω, ω) of polymer films doped with novel disazo dyes, which have a perfluoroalkylsulfonyl group as an electron acceptor and an extended π-electron system, are determined by second-harmonic generation (SHG) measurements at a wavelength of 1064 nm. Thin polycarbonate (PC) film doped with 4-(4-(4-perfluorobutylsulfonylphenylazo) naphthylazo)-N-ethyl-N-hydroxyethylaniline showed a large d
33 value, 67 pm/V. The decay of the d
33 value was slow due to the stability of the molecular arrangement in a polymer matrix at high temperature. The large d
33 values and the stability of polymer films doped with novel disazo dyes in this study are discussed in terms of electron acceptor substitution and an extended π-electron system.
Detailed Morphology of Rubbed Alignment Layers and Surface Anchoring of Liquid Crystals
Authors: Lee Eung Sang , Yasuhiro Saito Yasuhiro Saito , Tatsuo Uchida Tatsuo Uchida
Published: February 2005

The authors have measured surface morphology with wavelength longer than about 150 Å, of rubbed alignment layers using atomic force microscopy. Using the elastic continuum theory, we have quantitatively evaluated the azimuthal surface anchoring strength from the distortion of the surface morphology. We have also measured the azimuthal surface anchoring strength experimentally and compared the experimental results with the calculated values. The azimuthal surface anchoring strength obtained experimentally is more than two orders of magnitude larger than that obtained from the theoretical calculation. From these results, we found that anisotropy of the surface morphology with wavelength longer than about 150 Å does not strongly influence the alignment of liquid crystals on a rubbed surface.
Stable-Unstable Phase Transition of Densely Contract-Electrified Electrons on Thin Silicon Oxide
Authors: Morita Seizo , Sugawara Yasuhiro , Fukano Yoshinobu , Uchihashi Takayuki , Okusako Takahiro , Chayahara Ayumi , Yamanishi Yoshiki , Oasa Takahiko
Published: February 2005

Using reproducible and controllable contact electrification, we studied the charge dissipation of densely deposited electrons on a thin silicon oxide surface by electrostatic force measurement using a modified atomic force microscope. As a result, by increasing the density of contact-electrified electrons, we observed an appearance of a stable state of the contact-electrified electrons and its disappearance due to charge dissipation, i.e., a kind of stable-unstable phase transition. We also observed saturation of the deposited electron density with the spatial spread of deposited electrons.
P-Type ZnSe:N Prepared by Electron Cyclotron Resonance Radical Beam Doping during Molecular Beam Epitaxial Growth
Authors: Takeo Ohtsuka Takeo Ohtsuka , Kayoko Horie Kayoko Horie
Published: February 2005

ZnSe doped with nitrogen(N) has been prepared by molecular beam epitaxy using N2
*, N* nitrogen radicals, N2
+ ions and N atoms from an electron cyclotron resonance nitrogen plasma source. N-doped ZnSe/GaAs heteroepitaxial layers showed p-type conduction with net acceptor concentrations as high as 1.8×1018 cm-3, and the activation rate of N atoms was 60%. Photoluminescence spectra measured at 7 K from p-type ZnSe:N layers with net acceptor concentrations higher than 1018 cm-3 were dominated by two different donor-acceptor pair emission bands with zero phonon energies of 2.684 eV and 2.697 eV.
Accurate Determination and Measurement Error of Pretilt Angle in Liquid Crystal Cell
Authors: Han Kwan-Young , Tetsuya Miyashita Tetsuya Miyashita , Tatsuo Uchida Tatsuo Uchida
Published: February 2005

To measure the pretilt angle in a liquid crystal cell, the crystal rotation method is commonly used because it is very precise and measurements can be obtained rapidly. However when a liquid crystal cell with insufficient uniformity of the cell gap is used, a significant error occurs due to a shift in the measurement point. This shift is caused by refraction of the glass plate during rotation of the cell. In this paper, we estimate the magnitude of this error theoretically and propose a new method by which an accurate value can be obtained even if the cell gap is not uniform.
Scanning Tunneling Microscopy of √3×√3-Bi Reconstruction on the Si(111) Surface
Authors: Park Chan , Bakhtizin Raouf Z. , Tomihiro Hashizume Tomihiro Hashizume , Toshio Sakurai Toshio Sakurai
Published: February 2005

Bi-induced (√3×√3)R30° structures formed on the Si(111) surface are studied using scanning tunneling microscopy (STM) and LEED. Three distinct phases: monomer, trimer and honeycomb phases are identified for the first time by STM, depending on the Bi coverage, even though the √3×√3 symmetry has been always preserved in the LEED observation. At low coverages, Bi atoms are found to occupy the T4 site. In this adsorption geometry, a monomer phase (α-phase) are formed stably up to an ideal coverage of 1/3 ML. In trimer symmetry (β-phase) at saturation coverage of 1 ML, the individual atoms of the Bi clusters are clearly resolved. Between these two coverages, however, a honeycomb-type √3×√3 reconstruction has been also found, by STM, to co-exist with the trimer phase. This result reveals a new coverage dependent reconstruction process involving the √3×√3 reconstruction of Si(111) surface.
Low Temperature Sintering of P2O5-Added Cordierite Glass with Borosilicate Glass
Authors: Chen Shen-Li Fu
Published: February 2005

Borosilicate glass was adopted as a sintering aid to improve the sinterability of P2O5-added cordierite glass. The flux effect of borosilicate glass aids the coalescence of cordierite glass particles, which promotes the densification. Crystallization of cordierite glass is the major reaction during the sintering of cordierite glass with borosilicate glass. Besides the advantage of lower sintering temperature, the addition of borosilicate glass lowers the dielectric constant of sintered composites.
An a-Si:H Separated Absorption and Multiplication Type Photodiode with a-Si3N4 Blocking Layer
Authors: Sawada Kazuaki , Katayama Isao , Yamazaki Junichi , Kosugi Mitsuo , Takao Ando Takao Ando
Published: February 2005

Excess hole entrance from the electrode in highly reversebiased a-Si:H separated absorption and multiplication type photodiodes was successfully blocked using a thin a-Si3N4 layer. A smaller dark current was confirmed and the photoresponse time increased within a-Si3N4 layer. The slope of photoconversion characteristics was 1. These results indicated that there were no excess carriers entering from the electrode. The photocurrent of more than unit quantum efficiency was observed on this photodiode. The dependence of electrons and holes injected into the high-field region was examined and indicated the possibility of avalanche multiplication.
Heteroepitaxial Growth of Layered Semiconductor GaSe on a Hydrogen-Terminated Si(111) Surface*
Authors: Liu Kuang-Yu , Ueno Keiji , Fujikawa Yasunori , Koichiro Saiki Koichiro Saiki , Atsushi Koma Atsushi Koma
Published: February 2005

Layered III-VI semiconductor GaSe has been heteroepitaxially grown on HF-treated Si(111) surfaces. The HF-treated Si surface is chemically inactive because of the hydrogen termination of active dangling bonds. GaSe can be grown on such a surface through weak van der Waals interaction, which relaxes the lattice matching requirement. With careful control of the substrate temperature, thermal desorption of surface hydrogen atoms was prevented so that a single-domain film of GaSe could be grown with good crystallinity. Auger electron spectra and high-resolution electron energy loss spectra revealed high quality of the grown GaSe film.
Junction Properties and Gap States in Nb-Doped TiO2Thin Films
Authors: Takeshi Okamura Takeshi Okamura , Hideyo Okushi Hideyo Okushi
Published: February 2005

Nb-doped TiO2thin films were successfully prepared on p-type crystalline Si substrates using the sol-gel process. The current-voltage (I-V) characteristics of the heterojunctions between TiO2and Si show a rectification and the capacitance-voltage (C-V) characteristics an approximate linearC-2-Vrelationship in the reverse-bias condition. By application of an isothermal capacitance transient spectroscopy (ICTS) method on these junction diodes, it is found that two gap states are located at 0.027 eV and 0.22 eV below the conduction band edge (Ec).
Radiative Transition with Visible Light in Electrochemical Anodized Polycrystalline Silicon
Authors: Ueno Tomo , Akiba Yuichi , Shinohara Toshiro , Koyama Hideki , Nobuyoshi Koshida Nobuyoshi Koshida , Yasuo Tarui Yasuo Tarui
Published: February 2005

Radiative transition with visible light was observed by means of a porous layer made from polycrystalline silicon (poly-Si). Photoluminescence (PL) spectra were characterized as a function of initial poly-Si materials. For poly-Si formed by the casting method, a PL spectrum with the peak energy of 2.00 eV and the fullwidth at half maximum (FWHM) of 0.42 eV were obtained. For poly-Si formed by thermal CVD, the peak energy and the FWHM were 1.84 eV and 0.57 eV, respectively. On the basis of these findings, the structure of a highly developed display system, which contains TFT and luminous regions in the same poly-Si layer, was also proposed.
Thermally Activated Conductivity of Hydrogenated Amorphous Carbon Films Induced by Argon Plasma Bombardment
Authors: Chou Lih-Hsin , Wu-Tzung Hsieh Wu-Tzung Hsieh , Pu-Wei Wu Pu-Wei Wu
Published: February 2005

Hydrogenated amorphous carbon films have been prepared from plasma-enhanced chemical vapor deposition. Both the as-deposited films and those thermally annealed for two hours at 300°C exhibited insulating characteristics. Neither a thermally activated process nor a hopping mechanism was observed for the conductivity. An increase occurred in the conductivity by an order of five after two hours of subsequent treatment under Ar plasma for both the as-deposited and thermally annealed films. In addition, thermally activated conductivity with an activation energy of around 0.3 eV was observed.
Diffractive Scattering Experiment of H Atoms Using Laser and Ion Imaging Techniques
Authors: Tohru Kinugawa Tohru Kinugawa , Tatsuo Arikawa Tatsuo Arikawa
Published: February 2005

A novel scheme for detecting diffractive surface scattering of H atoms is proposed. This scheme is composed of three techniques: the laser photolysis of hydrogen-halide molecules to produce a monoenergetic H beam, the resonant detection of H atoms by multiphoton-ionization and the imaging of the diffractive scattering. A preliminary experiment, which recorded the image of H atoms generated from the HBr photolysis at 243 nm, determined the speed width to be 5.6%. The analysis of the results in terms of the speed distribution and the beam intensity assured the feasibility of the scheme.
Metalorganic Vapor Phase Epitaxy of CuGaS2 Using Ditertiarybutylsulfide as the Sulfur Source
Authors: Honda Tohru , Otoma Hiromi , Hara Kazuhiko , Junji Yoshino Junji Yoshino , Hiroshi Kukimoto Hiroshi Kukimoto
Published: February 2005

Ditertiarybutylsulfide has been used in place of the conventional sulfur source of hydrogen sulfide in metalorganic vapor phase epitaxy (MOVPE) of CuGaS2 using cyclopentadienyl-triethylphosphine-copper and triethylgallium as copper and gallium sources, respectively. It has been found that the premature reaction of the present sulfur source with the copper and gallium sources is negligible, resulting in a dramatic improvement of layer thickness uniformity. Ditertiarybutylsulfide also has an advantage over dimethyl and diethyl sulfides with respect to a decease in growth temperature in the growth of CuGaS2, implying its potential use in low-temperature MOVPE growth of other sulfide semiconductors such as ZnS.
P-Type Polysilicon Processing Temperature Reduction Using In Situ Boron-Doped Amorphous Silicon
Authors: Kobayashi Takashi , Simpei Iijima Simpei Iijima , Atsushi Hiraiwa Atsushi Hiraiwa
Published: February 2005

In situ boron-doped Si films are deposited in an amorphous state using Si2H6 and B2H6. By addition of B2H6, deposition at temperatures as low as 300°C is made possible with a sufficient deposition rate. In addition, the films show excellent step coverage. Resistivity of the films is fully reduced even after annealing at 650°C, which results from grain growth and dopant activation at low temperatures.
High Two-Dimensional Electron Mobility in Si Atomic-Layer Doped N-AlGaAs/GaAs Grown by Metalorganic Chemical Vapor Deposition
Authors: Toshiki Makimoto Toshiki Makimoto , Naoki Kobayashi Naoki Kobayashi
Published: February 2005

Si atomic-layer doped n-AlGaAs/GaAs structures have been grown by metalorganic chemical vapor deposition using triethyl sources, arsine and silane. Two dimensional electron mobility of 1.3×106 cm2/V·s is obtained at 4.2 K for a sheet electron concentration of 4.8×1011 cm-2. Because of the high quality of the two-dimensional electron gas, acoustic phonon scattering can be seen in the temperature dependence.
380 nm Photoluminescence Caused by Trace Na Impurity in High-Purity Synthetic Silica Glass
Authors: Shimbo Masaru , Hagiwara Hirotaka , Yoshiko Kimura Yoshiko Kimura , Shouzou Ariga Shouzou Ariga
Published: February 2005

In this study, 380 nm photoluminescence (PL), in the high-purity synthetic silica glass containing trace Na impurity, is observed upon excitation with ultraviolet (UV) light of wavelengths less than 240 nm. Its intensity increases with Na concentration exceeding the 1:1 concentration ratio of Na to Al. The nonbridging oxygen, pairing with the excess Na, is assumed to cause the PL, as well as an increase in the intensity of the 185 nm absorption band.
Effect Molecular Arrangement of Alignment Film for Liquid Crystals
Authors: Murata Makoto , Yoshida Eiichi , Masakazu Uekita Masakazu Uekita , Yoshihisa Tawada Yoshihisa Tawada
Published: February 2005

We have studied the direction of liquid crystals on multilayer alignment films composed of Langmuir-Blodgett films deposited onto rubbed films. Depositing more than three layers of Langmuir-Blodgett film onto the rubbed films changed the direction of the liquid crystals. The arrangement of the surface molecules of the alignment film was found to determine the alignment of the liquid crystals, and the use of a molecular layer of 3 nm thickness resulted in the alignment of the liquid crystals.
In Situ Optical Monitoring of Two-Dimensional Crystal Growth in Layer-by-Layer Chemical Vapor Deposition of YBa2Cu3Ox
Authors: Sakai Kenji , Hideaki Zama Hideaki Zama , Shunri Oda Shunri Oda
Published: February 2005

We have applied an in situ optical growth monitoring method to layer-by-layer chemical vapor deposition of YBaCuO thin films and observed a staircaselike change in reflectance. One step corresponds to one cycle of source gas supply combination and growth of one unit cell of the YBa2Cu3O
x
structure. This step is completed when Cu is supplied for the third time and the final layer consisting of a unit cell is applied. This result suggests that two-dimensional crystal growth of YBa2Cu3O
x
occurs. The calculation of reflectance change is consistent with the hypothesis that the reflectance change is due to layer-by-layer growth of YBaCuO.
Heteroepitaxial Growth of c-Axis-Oriented BaTiO3 Thin Films with an Atomically Smooth Surface
Authors: Gong Jianping , Kawasaki Masashi , Fujito Kenji , Tanaka Udai , Ishizawa Nobuo , Yoshimoto Mamoru , Koinuma Hideomi , Kumagai Masao , Hirai Kiyoto , Horiguchi Kenichi
Published: February 2005

C-axis-oriented barium titanate (BaTiO3) epitaxial films with an atomically smooth surface have been fabricated on SrTiO3{100} substrates using the pulsed laser deposition technique. The crystal structure and epitaxial orientation of the films have been analyzed by means of 2θ/θ X-ray diffractometry and 4-circle X-ray diffractometry. The highly oriented and epitaxial crystallinity is also shown by means of Rutherford backscattering spectrometry which gave a χmin of 1.7%. The atomically smooth surface comparable to that of the SrTiO3 substrate is revealed by means of atomic force microscopy. The breakdown electric field of the BaTiO3 film is as high as 106 V/cm.
Axial Microscopic Distribution of Grown-in Defects in Czochralski-Grown Silicon Crystals
Authors: Umeno Shigeru , Sadamitsu Shinsuke , Murakami Hiroki , Hourai Masataka , Shigeo Sumita Shigeo Sumita , Tatsuhiko Shigematsu Tatsuhiko Shigematsu
Published: February 2005

The axial microscopic distribution of grown-in defects in Czochralski silicon was studied by means of IR light scattering tomography (LST) and preferential etching. IR scattering defects (defects observed with LST) were found to degrade the gate oxide integrity yield, and the axial density distribution of IR scattering defects and flow patterns (wedge-shaped etch patterns) fluctuated with oxygen concentration fluctuations along the growth axis. However, the defect density did not depend directly on oxygen concentration. It is considered that the formation of IR scattering defects is related to the solid-liquid intertace temperature fluctuations.
Role of Species Generated from Phosphorus Sources in InGaP Growth Mechanism
Authors: Hori Hisao , Hironori Ishikawa Hironori Ishikawa , Masao Mashita Masao Mashita
Published: February 2005

Metalorganic chemical vapor deposition of InGaP using phosphine and tertiarybutylphosphine in various mixture ratios was carried out in order to elucidate the growth mechanism. It revealed that the two species generated from the phosphorus source, i.e., PH
x
(x=0-2) radicals and phosphorus molecules (P2 and/or P4), are necessary for epitaxial growth with high source material efficiency.
Superior Gettering Capability of Polycrystalline-Silicon Back-Sealed Silicon Wafers
Authors: Yamanaka Hideki , Kaneko Hisayuki , Yohko Haruta Yohko Haruta , Yoshio Iwamoto Yoshio Iwamoto
Published: February 2005

Polycrystalline-silicon back-sealed (PBS) wafers preserve high gettering efficiency as long as the back polysilicon film remains, even after exhaustion of the film through repeated oxidation. After complete consumption of the film, the high gettering efficiency decreases to some extent, but is still maintained by many oxidation-induced stacking faults and dislocations formed at the interface between the film and the silicon lattice during oxidation. All the Ni atoms and almost all the Cu atoms on the intentionally contaminated wafer surface are trapped in the back polysilicon film regardless of the density of oxygen precipitates.
Homogeneity of Bi2Sr2Ca1Cu2O8+δ Crystal Boules Grown by the Travelling Solvent Floating Zone Method
Authors: Ha Dong Han , Oka Kunihiko , Iga Fumitoshi , Nishihara Yoshikazu
Published: February 2005

We have grown Bi2Sr2Ca1Cu2O8+δ single crystals by the travelling solvent floating zone (TSFZ) method and measured the superconducting properties of various parts of grown crystal boules through Laue photographs, X-ray diffraction, resistivity and magnetization measurement. Generally, a part grown in an early stage shows metallic resistivity behavior, while a later part shows semiconducting behavior in a normal state and a lower superconducting transition temperature. However, after an appropriate one-day annealing under nearly the same conditions as when it was grown, we could obtain a homogeneous Bi2Sr2Ca1Cu2O8+δ crystal boule by the TSFZ method.
Raman Scattering of Gas-Evaporated Ge with a Structure Other Than the Diamond Lattice
Authors: Yoshiro Sasaki Yoshiro Sasaki , Chuji Horie Chuji Horie
Published: February 2005

Germanium particles have been prepared by evaporation in Ar gas. We have found Ge with a structure other than the diamond lattice in these samples by Raman scattering. The frequencies of Raman lines due to Ge with the nondiamond structure agree well with those of phonons at the X-point in Ge with the diamond structure.
Correlation between Fourier-Transform-Infrared (FTIR) Spectra and Temperature Dependence of Dielectric Properties of SrTiO3 Thin Films
Authors: Matsui Ken-ichi , Masahiro Taga Masahiro Taga , Takeshi Kobayashi Takeshi Kobayashi
Published: February 2005

SrTiO3 (STO) thin films were grown on (111)Pt/(100)MgO substrates at several deposition temperatures T
D (350-710°C) and characterized. Deposition temperatures T
D≥540°C yielded epitaxial (100)STO films but they strongly affected both the optical and dielectric properties of films. The LO (longitudinal optical phonon) absorption spectra and ∂ε/∂T (temperature coefficient of the dielectric constant) showed similar dependence on T
D, and optimization was achieved at T
D=665°C. However, the highest value of the room temperature ε (=313ε0, where ε0 is the vacuum dielectric costant) was obtained from the film grown at T
D=540°C.
Preparation of High Quality Barium Fluoride Thin Film by Chemical Vapor Deposition
Authors: Hirotsugu Sato Hirotsugu Sato , Shungo Sugawara Shungo Sugawara
Published: February 2005

High quality BaF2 (111) thin film was epitaxially grown on a CaF2 (111) substrate by chemical vapor deposition. An novel fluorinated Barium β-diketone chelate; Ba(ofhd)2 was used as the source material. Oxygen was introduced to complete the fluorination of the barium precursor. The full width at half maximum (Δθ50) of the X-ray rocking curve of the film was 3-10 min. RBS spectra showed that the χmin value of the BaF2 film was 3.7% and that of BaF2 single crystal was 2.8%. SIMS analysis confirmed that carbon and oxygen incorporation was at background levels.
Diamond-Like Carbon Film Deposition by Super-Wide Electron-Cyclotron Resonance Plasma Source Excited by Traveling Microwave
Authors: Ishii Akira , Sakaguchi Yoshiyuki , Minomo Shoichiro , Taniguchi Michio , Kobayashi Masato Sugiyo
Published: February 2005

An electron-cyclotron resonance (ECR) plasma source which generates a long and narrow plasma 500 mm in length has been developed. The plasma is generated by a 2.45 GHz traveling microwave which is supplied through a slot antenna prepared in the waveguide in a magnetic field generated by permanent magnets. Diamond-like carbon (DLC) films were deposited in a wide zone 340 mm in width. The variation of film thickness was less than 10%. The resistivity of the DLC film was ∼9.62×1011 Ω·cm and permittivity, 3.63. The prepared Al/DLC/Si metal/insulator/semiconductor (MIS) diode revealed fairly good field effect in its capacitance-voltage curve.
Anharmonic Phonon Structure in the Tunneling Conductance of Bi-Cuprates
Authors: Ohuchi Masahiko , Miyakawa Nobuaki , Shiina Yasushi , Daisuke Shimada Daisuke Shimada , Nobuo Tsuda Nobuo Tsuda
Published: February 2005

Phonon structures in the tunneling conductance must be properly normalized to evaluate the intensity of the electron-phonon interaction. However, this is very difficult because of the absence of the exact normal-state conductivity. Therefore we propose another method to judge whether or not the intensity becomes stronger with a critical temperature T
c. This method compares the intensity of anharmonic structures, which are normalized to the single-phonon structures, between high- and low-T
c substances. Our data for Bi-cuprates strongly suggest that the electron-phonon interaction is stronger in higher-T
c substances.
Directional Growth of Extruded YBa2Cu3O7-x Superconductors
Authors: Shin Woosuck , Shim Sojeong , No Kwangsoo , Kim Guneik Jang
Published: February 2005

Textured bulk YBa2Cu3O
x
high-temperature superconductor samples were fabricated through the extrusion and the directional growth of superconductor grains reacted from Y2BaCuO5, BaCuO2 and CuO powder mixtures. Wires of 2 mm in diameter were extruded to several hundred meters. The directional growth under proper conditions eliminated extrusion defects such as pores and voids, and the critical current of the sample increased. The sample grown directionally at 1155°C consisted of a dense microstructure and an almost perfectly aligned grain structure, and showed a high critical current density of over 104 A/cm2.
Diffusivity of Self-Interstitials and Vacancies in Silicon
Authors: Takahisa Okino Takahisa Okino
Published: February 2005

In my previous paper [Jpn. J. Appl. Phys. 31 (1992) 965], the self-interstitial and vacancy concentrations in silicon were obtained as a function of the diffusion time by analysing the experimental data for oxidation-enhanced/retarded diffusions of P/Sb. Using these results and the approximate solutions obtained from well-known diffusion equations of self-interstitials and vacancies, the self-interstitial and vacancy diffusivities, i.e., D
I=2.3×10-9 cm2/s and D
V=2.3×10-10 cm2/s, are determined at 1100°C. Furthermore, the thermal equilibrium concentrations of self-interstitials and vacancies, i.e., C
I
0=3.4×1016 cm-3 and C
V
0=2.1×1017 cm-3, are also determined.
Laser-Induced Electronic Emissions of Si Atoms from Si(100) Surfaces
Authors: Kanasaki Jun'ichi , Yu In Keun , Yasuo Nakai Yasuo Nakai , Noriaki Itoh Noriaki Itoh
Published: February 2005

We have carried out highly sensitive measurements of Si° atoms from the Si(100) surfaces emitted by irradiation with 2.48 eV laser pulses. The results indicate all characteristics of the defect-initiated emissions of electronic origin obtained for the emission of Ga° atoms from GaP and GaAs surfaces: we found that the yield is a superlinear function of the fluence and decreases first rapidly and then slowly as the irradiation with laser pulses is repeated. The emission yield after eliminating the rapidly decaying component is found to be enhanced by deposition of submonolayer Br atoms.
Field Ion-Scanning Tunneling Microscopy of Metallofullerenes Adsorbed on the Si(100)2×1 Surface
Authors: Wang Xiang-Dong , Hashizume Tomihiro , Xue Qikun , Shinohara Hisanori , Saito Yahachi , Yuichiro Nishina Yuichiro Nishina , Toshio Sakurai Toshio Sakurai
Published: February 2005

The Sc@C74 and Sc2@C74 metallofullerenes (MF), adsorbed on the Si(100)2×1 clean surface were successfully studied for the first time by the STM. The STM showed that the MF molecules were imaged to be spherical, quite similar to those of C60, C70, and C84, suggesting that Sc atoms were trapped inside the fullerene cage and that the charge is at least partially delocalized over the sphere of the cage. Statistical analysis of both the diameter and height of MF, compared with those of C60, showed that the diameter of the Sc@C74 and Sc2@C74 cages was 9.5 Å in average, larger than that of the pristine fullerenes.
Wavelength Dependence of Junction Characteristics of Poly(3-alkylthiophene)/C60Layer
Authors: Morita Shigenori , Zakhidov Anvar A. , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

A poly(3-alkylthiophene)/C60junction device is provided. Its photoresponse gives evidence of the photoinduced charge transfer between poly(3-alkylthiophene) and C60. The photovoltaic effect in this device is observed. The current-voltage characteristics are found to depend on the wavelength of the illumination light.
Determination of Evaporation Rate and Vapor Pressure of Organic Monomers Used for Vapor Deposition Polymerization
Authors: Takahashi Yoshikazu , Matsuzaki Kanenori , Iijima Masayuki , Fukada Eiichi , Tsukahara Sonoko , Murakami Yukimasa , Maesono Akikazu
Published: February 2005

Thermogravimetry (TG) and the Langmuir equation have been employed for the determination of the temperature dependence of the evaporation rate and saturated pressure of monomers used in vapor deposition polymerization (VDP). The measuring process utilizes the evaporation of monomers in vacuum. The ranges of the evaporation rate and saturated pressure of monomers as determined by the TG technique are from 10-2 to 10-5 mol/m2·s and from 1 to 10-3 Pa, respectively. Comparison of the evaporation rate vs temperature relation and the melting point of monomers determines whether the evaporation involves sublimation from a solid surface or evaporation from a liquid surface.
Selective Dissociative Ionization of SiH4, Si2H6 and Si3H8 by Electron Impact in Supersonic Free Jets
Authors: Motooka Teruaki , Fons Paul , Hiroshi Abe Hiroshi Abe , Takashi Tokuyama Takashi Tokuyama
Published: February 2005

Low-energy (E=10-14 eV) electron-impact decomposition of SiH4, Si2H6, and Si3H8 into ionic species in a pulsed supersonic free jet has been investigated using quadrupole mass spectrometry. Si+ was the common primary dissociated product for E≤13 eV, while at E=14 eV, SiH2
+ and SiH3
+ became the primary species in the dissociation of SiH4 and Si2H6, respectively.
Preparation of Ag-I Intercalated Bi2Sr2CaCu2Oy Superconductor
Authors: Kumakura Hiroaki , Ye Jinhua , Shimoyama Jun-ichi , Hitoshi Kitaguchi Hitoshi Kitaguchi , Kazumasa Togano Kazumasa Togano
Published: February 2005

We have found that silver and iodine can be intercalated simultaneously into a Bi2Sr2CaCu2O
y
superconductor. By this intercalation, the lattice parameter along the c-axis was significantly expanded from 30.9 to 45.6(=22.8×2) Å. From X-ray diffraction analysis, it was assumed that silver and iodine atoms are inserted between double Bi-O layers in the stacking sequence of Bi-I-Ag-I-Bi, and that the stoichiometric composition is AgI2Bi2Sr2CaCu2O
y
. T
c(onset) of this intercalated new material is 60.7 K, which is comparable to that of the stage-1 IBi2Sr2CaCu2O
y
obtained through the same heat treatment.
Superconductor Wiring in Multichip Module for Josephson LSI Circuits
Authors: Tanahashi Shigeo , Kubo Takanori , Kawabata Kazuhiro , Jikuhara Ryouji , Kaji Gentaro , Terasawa Masami , Nakagawa Hiroshi , Aoyagi Masahiro , Kurosawa Itaru , Takada Susumu
Published: February 2005

Nb/polyimide stacked layers on a multilayer ceramic substrate makes it possible to fabricate superconducting off-chip wiring for control signal lines. This superconducting multichip module (SuperMCM) also provides matching circuits for the clock signal and DC bias circuits beneath the superconducting transmission lines. The first prototype SuperMCM in the world successfully made,which has been designed to drive Josephson LSI chips at the highest clock frequency of 1.2 GHz.
Relationship between Second- and Third-Order Nonlinear Optical Susceptibilities due to Electronic Polarization
Authors: Ryuji Morita Ryuji Morita , Mikio Yamashita Mikio Yamashita
Published: February 2005

A simple semitheoretical relation between ultrafast nonlinear susceptibilities χ(2) and χ(3) due to the electronic polarization in the nonresonant region for noncentrosymmetric materials is derived. This result well explains experimental data.
Scanning Electron Microscope Observation of Ridge Structures Formed on (100) and (110) Gd3Ga5O12 Substrates
Authors: Katoh Yujiro , Naoto Sugimoto Naoto Sugimoto , Akiyuki Tate Akiyuki Tate
Published: February 2005

Straight ridge patterns about 4 µm high are formed in the [01̄2] direction on a (100)Gd3Ga5O12(GGG) single crystal substrate and in the [11̄2] direction on a (110)GGG substrate by argon ion-beam etching and subsequent soaking in a hot phosphoric acid solution. The ridge shapes are observed with a scanning electron microscope (SEM). The crystal faces, which appear on the ridge side walls, are examined. Although the ridge directions are polar, the ridge cross sections are symmetrical and faces with the same indices appear on both side walls. Side wall roughness is considerably influenced by the accuracy of the ridge direction alignment.
Synthesis of a New Cubic Conductive Cu6O8-yMX (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) Family
Authors: Sugise Ryoji , Ohdan Kyoji , Hamamoto Toshikazu , Kashiwagi Kouichi , Shirai Masashi , Yazawa Ichiro , Ihara Hideo
Published: February 2005

A new cubic Cu6O8-y
MX family (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) was prepared. These compounds showed metallic resistivity and paramagnetism. The Cu6O8-y
MX compounds could be easily synthesized when a trivalent metal element (M) whose oxide (M2O3) has a cubic Tl2O3-type structure was used. These compounds were prepared in the thermal decomposition process of a mixed copper nitrate, copper chloride and metal element oxide solution. The lattice constants of the Cu6O8-y
MX compounds were related to those of M2O3.
Epitaxial Growth of α-Fe Film on Si(111) Substrate by Low-Energy Direct Ion Beam Deposition
Authors: Shimizu Saburo , Naruyasu Sasaki Naruyasu Sasaki , Seiji Seki Seiji Seki
Published: February 2005

Fe film growth on Si(111) substrate was carried out by low-energy direct ion beam deposition. Fe films of about 1000 Å thick were grown at Fe+ ion energies of 10 eV, 20 eV, 50 eV and 100 eV without removing the native oxide layer on the Si substrate. Single-crystal α-Fe(111) films were obtained at 20 eV, 50 eV and 100 eV at room temperature, while (110)-preferred-oriented α-Fe film was obtained at 10 eV. Cross-sectional high-resolution transmission electron microscopy (TEM) studies show that the removal of the native oxide layers on the Si substrates by Fe+ ion irradiation results in the epitaxial ordering of the α-Fe films when the films are grown at 20 eV, 50 eV and 100 eV.
Ferroelectric PbTiO3 Thin Films Prepared by Multi-Ion-Beam Sputter and Ion-Assisted Deposition
Authors: Kanno Isaku , Kamada Takeshi , Hayashi Shigenori , Masatoshi Kitagawa Masatoshi Kitagawa , Takashi Hirao Takashi Hirao
Published: February 2005

Very thin PbTiO3 films of ∼350 Å were synthesized in situ on MgO substrates by multi-ion-beam sputter deposition using metal targets. Crystalline films in a perovskite phase were obtained at a low substrate temperature of 415°C by means of reactive sputtering in an oxygen ambient. The formation of crystal phases was studied as a function of deposition parameters, and ion-beam-assisted deposition using an electron cyclotron resonance (ECR) plasma was also employed to improve the film growth. Low-energy (<300 eV) oxygen ion bombardment was found to enhance c-axis orientation and crystallization at a lower substrate temperature of 400°C.
Selective Annealing Utilizing Single Pulse Excimer Laser Irradiation for Short Channel Metal-Oxide-Semiconductor Field-Effect Transistors
Authors: Tsukamoto Hironori , Yamamoto Hiroshi , Takashi Noguchi Takashi Noguchi , Toshiharu Suzuki Toshiharu Suzuki
Published: February 2005

Excimer laser annealing (ELA) for metal-oxide-semiconductor (MOS) devices of less than a quarter micron was investigated. A new structure for the electrodes and new processing were developed to prevent deformation of the finely patterned electrodes during ELA. For a wavelength of 308 nm of the excimer laser, SiO2 films of 100 nm were deposited on the electrodes to reflect the laser light effectively. Fine metal-oxide-semiconductor field-effect transistors (MOSFETs) with shallow junction depth of 50 nm and fine patterned gate of 0.3 µm were realized and their characteristics were evaluated.
Properties of Ce-Substituted Yttrium Iron Garnet Film Containing Indium Prepared by RF-Sputtering
Authors: Mino Shinji , Tate Akiyuki , Uno Takehiko , Toshihiro Shintaku Toshihiro Shintaku , Atsushi Shibukawa Atsushi Shibukawa
Published: February 2005

We studied the magneto-optical and magnetic properties of Ce-substituted yttrium iron garnet film containing indium. The magnetic anisotropy energy K
u was estimated at -1.58×104 erg/cm3 in the in-plane direction using ferromagnetic resonance. The λ110 value is measured to be 1.56×10-6 which is much smaller than that estimated from other reported values. It appears that the measured K
u can not be explained only in terms of the stress-induced magnetic anisotropy.
Molecular Mechanics and Dynamics of Leukocyte Recruitment During Inflammation
Authors: Simon Scott I. , Green Chad E.
Published: February 2005

▪ Abstract  Discovery of new genes and proteins directly supporting leukocyte adhesion is waning, whereas there is heightened interest in the cell mechanics and receptor dynamics that lead from transient tethering via selectins to affinity shifts and adhesion strengthening through integrins. New optical tools enable real-time imaging of leukocyte rolling and arrest in parallel plate flow channels (PPFCs), and detection of single-molecule force spectroscopy provides an inner view of the intercellular adhesive contact region. Leukocyte recruitment during acute inflammation is triggered by ligation of G protein–coupled chemotactic receptors (GPCRs) and clustering of selectins. This, in turn, activates β2-integrin (CD18), which facilitates cell capture and arrest in shear flow. This review provides a conceptual model for the molecular events supporting leukocyte recruitment.
Multiethnic Cities in North America
Authors: Fong Eric , Shibuya Kumiko
Published: February 2005

The growing Hispanic and Asian populations in most major North American cities have drastically transformed the urban demographic landscape to become racially and ethnically diversified. We review literature on multiethnic cities by focusing on three important aspects of urban structures and processes: racial and ethnic residential patterns, ethnic businesses, and the performance of racial and ethnic groups in the labor market. Although the literature has identified many factors that shape these urban structures and processes, our discussion specifically focuses on the effects of multigroup contexts on urban structures and processes. We focus and compare four major racial and ethnic groups: whites, blacks, Hispanics, and Asians. Specific ethnic subgroups of all four groups are also discussed.
Is the renal production of erythropoietin controlled by the brain stem?
Authors: von Wussow Ursula , Klaus Janina , Pagel Horst
Published: February 2005

Although the structure and function of erythropoietin (Epo) are well documented, the mechanisms of the regulation of the renal synthesis of Epo are still poorly understood. Especially, the description of the localization and function of the O2-sensitive sensor regulating the renal synthesis of Epo is insufficient. A body of evidence suggests that extrarenal O2-sensitive sensors, localized particularly in the brain stem, play an important role in this connection. To support this concept, high cerebral pressure with consecutive hypoxia of the brain stem was generated by insufflation of synthetic cerebrospinal fluid into the catheterized cisterna magna of rats. When the cerebral pressure of the rats was above the level of their mean arterial blood pressure or the high cerebral pressure persisted for a longer period (≥10 min), the Epo plasma concentration increased significantly. Bilateral nephrectomy or hypophysectomy before initiation of high intracranial pressure abolished this effect. Systemic parameters (heart rate, blood pressure, PaO2, PaCO2, arterial pH, renal blood flow, glucose concentration in blood) were not affected. Other stressors, like restricting the mobility of the rats, had no effect on Epo production. Hence, the effect of high cerebral pressure on renal synthesis of Epo seems to be specific. Increasing cerebral hydrostatic pressure leads to increased renal synthesis of Epo. Obviously, during hypoxia, cerebral O2-sensitive sensors release humoral factors, triggering the renal synthesis of Epo. The structure and function of these “Epo-releasing-factors” will have to be characterized in future experiments.
Growth hormone and testosterone interact positively to enhance protein and energy metabolism in hypopituitary men
Authors: Gibney James , Wolthers Troels , Johannsson Gudmundur , Umpleby A. Margot , Ho Ken K. Y.
Published: February 2005

We investigated the impact of growth hormone (GH) alone, testosterone (T) alone, and combined GH and T on whole body protein metabolism. Twelve hypopituitary men participated in two studies. Study 1 compared the effects of GH alone with GH plus T, and study 2 compared the effects of T alone with GH plus T. IGF-I, resting energy expenditure (REE), and fat oxidation (Fox) and rates of whole body leucine appearance (Ra), oxidation (Lox), and nonoxidative leucine disposal (NOLD) were measured. In study 1, GH treatment increased mean plasma IGF-I ( P < 0.001). GH did not change leucine Ra but reduced Lox ( P < 0.02) and increased NOLD ( P < 0.02). Addition of T resulted in an additional increase in IGF-I ( P < 0.05), reduction in Lox ( P < 0.002), and increase in NOLD ( P < 0.002). In study 2, T alone did not alter IGF-I levels. T alone did not change leucine Ra but reduced Lox ( P < 0.01) and increased NOLD ( P < 0.01). Addition of GH further reduced Lox ( P < 0.05) and increased NOLD ( P < 0.05). In both studies, combined treatments on REE and Fox were greater than either alone. In summary, GH-induced increase of circulating IGF-I is augmented by T, which does not increase IGF-I in the absence of GH. T and GH exerted independent and additive effects on protein metabolism, Fox and REE. The anabolic effects of T are independent of circulating IGF-I.