bluuebunny/crossref_metadata_2025 huggingface dataset:
Field-Induced Anistropy in Bi1.7Pb0.3Sr2Ca2Cu3Oy High-Tc Superconductors
Authors: Lee Joo-Il , Kim Mun-Seog , Yu Seong-Cho , Oh Suhk-Kun , Lim Woo-Young , Chang Min-Su
Published: February 2005

The angular dependence of the magnetization of Bi1.7Pb0.3Sr2Ca2Cu3O
y
was studied by rotating the sample relative to the applied magnetic field. At low fields and at the nitrogen temperature, the irreversible part of the field-cooled magnetization, M
irr, rotates with the sample like a rigid body. Above some angle φ*, the rigid nature of the sample is diminished, and a part of M
irr disappears. This feature is quite similar to what had been observed in Y1Ba2Cu3O7 compounds.
Multipulse Recording Method for Pulse-Width Modulation Recording on an Erasable Phase Change Optical Disk
Authors: Ohno Eiji , Nishiuchi Kenichi , Ishibashi Kenzoh , Noboru Yamada Noboru Yamada , Nobuo Akahira Nobuo Akahira
Published: February 2005

A laser irradiation scheme “multipulse (MP) recording method” was examined on an erasable phase change optical disk having a chalcogenide alloy film. Each recording mark in the amorphous state is formed on the precrystallized disk by irradiation of successive multiple short pulses, the widths or periods of which gradually change. This markedly reduces the teardrop-shaped distortion of the mark. For the recording examination of 345 kHz single-frequency signals at 1.4 m/s of linear velocity, CNR>50 dB and SHD<-40 dB were obtained by the MP method, while the SHD by the conventional method remained -30 dB. The simple electrical device prepared, which produces 9 kinds of multiple pulses according to the signal lengths, 3T to 11T, successfully recorded the eight to fourteen modulation (EFM) signals of the audio compact disk format with small jitter at 1.25 m/s.
Admittance Spectroscopy of Cu-Doped ZnO Crystals
Authors: Yasuo Kanai Yasuo Kanai
Published: February 2005

An experiment to determine the electronic state of Cu in a ZnO crystal is performed using the admittance spectroscopy technique at the frequency range from 100 Hz to 100 kHz and the temperature range from -160 to +80°C. The results obtained are summarised as follows: Cu behaves as an acceptor in ZnO and its energy level locates at 0.17 eV below the bottom of the conduction band. The values of the electron capture cross section are found to decrease with increasing Cu concentration, and they are determined as 2-12×10-17 cm2.
Ferroelectric Behavior of Vinylidenefluoride-Trifluoroethylene-Hexafluoropropylene Terpolymers
Authors: Maeda Kazuhiko , Shigeru Tasaka Shigeru Tasaka , Norihiro Inagaki Norihiro Inagaki
Published: February 2005

The ferroelectric vinylidenefluoride-trifluoroethylene-hexafluoropropylene (VDF-TrFE-HFP) terpolymers with VDF contents of 54 mol% to 57 mol% and HFP contents of 0 mol% to 6 mol% were investigated by differential scanning calorimetry, X-ray diffraction and dielectric constant. The crystallinity of ferroelectric form I crystal decreased with increasing HFP content in the terpolymer. This is due to a lattice expansion and a destruction of unit cells containing the HFP as a large defect. Curie temperature depression of about 25°C was observed in the sample with 6 mol% HFP content. The correlation between the change of the Curie temperature and the lattice spacing was found in the terpolymers.
Instantaneous Temperature Measurement in a Flame by Rapid-Frequency-Scan Laser Spectroscopy
Authors: Honda Chikahisa , Fujiyoshi Shin'ichiro , Kawamoto Hideo , Muraoka Katsunori , Maeda Mitsuo , Masanori Akazaki Masanori Akazaki
Published: February 2005

A new technique for instantaneous rotational temperature measurement of OH radicals has been developed for combustion diagnostics using a rapid-frequency-scan (RAFS) laser system. The RAFS laser excites OH radicals (X2Π←A2Σ+) in an atmospheric flame, and the intensities of rotational lines are measured with laser-induced fluorescence spectroscopy (LIF), and the rotational temperature of the flame is determined. Measurement of the spatial distribution of the temperature along the laser beam is demonstrated by the parallel sampling of the LIF signals in a single laser shot.
Molecular Structure and Electric Breakdown of Ethylene/Silane Copolymers
Authors: Ishino Iwao , Hikita Masayuki , Mizutani Teruyoshi , Ieda Masayuki
Published: February 2005

Crosslinking characteristics and electric breakdown (F}B) of various kinds of ethylene/silane random copolymers were investigated. The crosslinking rate was found to increase with the reactivity of the silane species, whereas the F
B did not significantly differ among the samples with different silane radicals. The F
B was measured in a temperature range of 30-160°C using dc and impulse voltages. The results revealed that the dc F
B was larger than the impulse one below the critical temperature T
c for the crosslinked silane/ethylene copolymers with two different gel contents. The difference was interpreted in terms of space charge effect. T
c moved to higher temperature with increasing the degree of crosslinking. X-ray induced TSC measurements allowed observation of new TSC peaks at high temperatures due to the crosslinking giving rise to carrier traps, consistent with the breakdown result.
Wavelength Characterisation of Ferroelectric Liquid Crystal Cells
Authors: C. R. Lavers C. R. Lavers , J. R. Sambles J. R. Sambles
Published: February 2005

Measurements are presented for the optical dielectric constants of a ferro-electric liquid crystal (MIX 783) over the visible part of the spectrum using the excitation of leaky guided Fabry-Perot optical modes. Incident monochromatic polarised light is coupled into resonant guided modes of the liquid crystal system which are then observed as sharp dips in the reflected signal at specific incident angles. It is possible to fit all the experimental data across the visible region of the spectrum with a uniaxial optic dielectric tensor and a model of the alignment which has bent chevron layers. Using this technique precise values were obtained for the refractive indices of the liquid crystal mixture MIX 783.
The Structural Changes of Indium-Tin Oxide and a-WO3 Films by Introducing Water to the Deposition Processes
Authors: Shigesato Yuzo , Hayashi Yasuo , Masui Akio , Takeshi Haranou Takeshi Haranou
Published: February 2005

Indium-tin oxide (ITO) films and amorphous WO3 (a-WO3) films were deposited by DC magnetron sputtering and EB evaporation, respectively, under different water partial pressures (p
H2O). The ITO films sputtered under higher p
H2O showed higher resistivities because of the decrease in hall mobility and had rather different orientation distributions of the crystal axis of the grains. It was found from XPS analyses that the In-O-H bonds which were not found in the films existed at the interface between the glass substrates and the ITO films, and much more of these bonds existed for the higher p
H2O films. This suggests that the structural change which increased the resistivity occurred at the first stages of the formation of the films. For the a-WO3 films deposited under high p
H2O, the decreases of order parameters and increases of W=O bonds were observed by Raman spectroscopy, indicating a decrease in microcrystal sizes.
Highly Conductive Tungsten Thin Films Prepared by the Plasma-Assisted Silane Reduction Process
Authors: Kim Yong Tae , Min Suk-Ki , Hong Jong Sung , Kim Choong-Ki
Published: February 2005

We have studied the properties of plasma-enhanced chemical vapor deposited tungsten (PECVD-W) thin films according to the variations of reactant mixtures, SiH4/WF6 ratio, deposition temperature and RF power density. As the result, it is found that the resistivity of PECVD-W is reduced from 70 to 40 µΩ-cm with the addition of SiH4 (SiH4/WF6 ratio=1) even at a lower temperature (220°C) than in the previous works. For the further reduction of resistivity, with increasing deposition temperature from 220 to 360°C, 40 µΩ-cm is reduced to 10 µΩ-cm, and (110), (200) and (211) oriented α-phase grain growth is observed. The deposition rate is increased with the increase of the SiH4/WF6 ratio up to 1.5. However, at the SiH4/WF6 ratio of 2, the deposition rate decreases and β peaks are observed at the expense of the α-phase. The Auger in-depth profile indicates that 20 atomic % is incorporated into the deposition process.
Analysis of Sputtered Neutrals by Nonresonant Multiphoton Ionization. II. A Quantitative Composition Analysis of Cu-Al Alloy
Authors: Eizoh Kawatoh Eizoh Kawatoh , Ryuichi Shimizu Ryuichi Shimizu
Published: February 2005

A sputtered neutral mass analysis by multiphoton ionization was applied to the composition analysis of Cu-Al alloy. The reliability of the quantitative estimation of the signal intensity was improved by using an ion-counting system with a simple flight tube. Measured intensities of Cu and Al from a Cu-Al alloy sample represented atomic compositions with high accuracy. Errors in the estimation of the surface chemical composition are within several percent.
Statistics of Secondary Electron Emission for Low-Energy Electron Impact on Copper
Authors: Kaoru Ohya Kaoru Ohya , Ichiro Mori Ichiro Mori
Published: February 2005

Secondary electron emission statistics of copper bombarded by electrons are simulated with the Monte Carlo technique. Special features of the statistics are a large probability for no secondary electron and a wide spead of the probabilities to more electrons. Dependences of the secondary electron emission on the energy and the angle of incidence are investigated by using the emission statistics, the energy and the angular distibutions of emitted electrons.
X-Ray Reemission from Soft-X-Ray-Heated Gold Plasma
Authors: Kondo Kiminori , Nishimura Hiroaki , Yoshiaki Kato Yoshiaki Kato , Sadao Nakai Sadao Nakai
Published: February 2005

X-ray reemission from a gold plasma, which is heated by intense soft X-ray radiation (4.4×1012 W/cm2), has been observed. The reemission rate increases with time and reaches 50% at the maximum. Temporal evolution of the X-ray reemission is analyzed in terms of a self-similar solution for the ablative heat wave which we modify to account for the time variation of the heating X-ray.
Evaluation of Error Poloidal Field in an Iron-Cored Tokamak
Authors: Taro Sometani Taro Sometani , Yasunori Mizuno Yasunori Mizuno
Published: February 2005

The error field (magnetic induction) conjectured to originate from the connecting conductors and the turnback coil of toroidal field coils and the poloidal field, which is applied to compensate the error field and the electron toroidal drift, are computed with semianalytic expressions. The vertical component of the computed error field agrees roughly with the error vertical field which is evaluated indirectly by determining the optimum value of the applied poloidal field from the standpoint of the tokamak gas breakdown. The computed value of the applied poloidal field produced by simple circular coils agrees satisfactorily with the directly measured one.
Measurement of Surface Vacuum Potential from the Energy Spectrum of the Secondary Electron in the Scanning Electron Microscope
Authors: Nakamae Koji , Hiromu Fujioka Hiromu Fujioka , Katsumi Ura Katsumi Ura
Published: February 2005

A measurement method for determining the contact potential between the specimen and the analyzer from an S-curve (an integrated curve of secondary electron energy distribution) in the scanning electron microscope is described. The measured S-curve is best-fitted to the calculated S-curve assuming the secondary electron energy distribution and the instrumental function of the analyzer. The work function of the retarding electrode in the analyzer was calibrated by the use of thermionic emission from a heated W filament. The work function of acid-cleaned Cu was 4.71 V, while that of untreated Al was 3.64 V. It is shown that the previously reported charging characteristics of an electrically floating gate in the MOS structure under electron beam irradiation are well explained by taking account of the surface vacuum potentials. The work function of insulator SiO2 was estimated to be on the order of 7 V.
Video Tracking of a Fatigue Crack with a Long Distance Microscope
Authors: Fukui Hisao , Hasegawa Jiro , Ichida Kuniji , Ohkouchi Teiichi
Published: February 2005

With a long distance microscope and a TV camera connected together, the area of the fatigue-crack tip is observed in real time in the present experiment. As the initiation and the propagation of the fatigue-crack are recorded on a video tape, we can obtain the information on the cracking process, that is to say, the number of fatigue cycles till crack initiation, crack growth rate, crack-opening displacement (COD) and so on. The most characteristic point is that the behavior of the crack growth can be monitored by a highly magnified image with the TV video camera, even if we are not engaged in the fatigue test.
Hydrogen Desorption Behaviors of HF-Treated Silicon Wafer
Authors: Tomita Hiroshi , Tadashi Kikuchi Tadashi Kikuchi , Keiichi Furuya Keiichi Furuya
Published: February 2005

Hydrogen desorption behaviors of HF-treated silicon wafer and decomposition reaction of water vapor on an HF-treated silicon surface under UHV were investigated by means of thermal desorption spectroscopy (TDS). When an HF-treated silicon surface was annealed in high vacuum, silicon trihydride species (SiH3) desorbed from the HF-treated silicon surface at 580°C, and SiH2F species which had probably the same structure as SiH3 on an HF-treated silicon surface desorbed and then recombined to form volatile SiH3-F with adjacent hydrogen at 580°C in addition to H2 desorption at about 400, 500 and 600°C. The decomposition reaction of water vapor was found to proceed in two steps at 500 and 750°C on a dehydrogenated silicon surface. The reaction made background hydrogen increase at 500 and 750°C in H2
+ spectra from HF-treated silicon wafer.
Room Temperature Hot Electron Transistors with InAs-Notched Resonant-Tunneling-Diode Injector
Authors: Seabaugh Alan , Kao Yung-Chung , Randall John , William Frensley William Frensley , Ali Khatibzadeh Ali Khatibzadeh
Published: February 2005

Room temperature operation is achieved in In(GaAl)As/InGaAs resonant-tunneling hot electron transistors (RHET) grown by molecular beam epitaxy on InP substrates. RHETs with base widths of 10, 40 and 60 nm are fabricated and all exhibit room temperature dc current gain greater than 2, with gain as high as 12 observed at resonance in the 40 nm base device. To our knowledge these are the first In(GaAl)As hot electron transistors to exhibit 300 K gain of this magnitude. In addition, the transistors also exhibit strong negative transconductance and a unique negative peak-to-valley current ratio. S-parameter measurements of the 40(60) nm base RHET give values for f
T and f
MAX of 67(54) and 41(11) GHz respectively.
Plasma-Chemical Vapor-Deposited Silicon Oxide/Silicon Oxynitride Double-Layer Antireflective Coating for Solar Cells
Authors: Noboru Shibata Noboru Shibata
Published: February 2005

Si-oxide/Si-oxynitride (SiO
X
/SiN
X
O
Y
) double-layer films were prepared by controlling the operation parameters of plasma chemical vapor deposition in N2-diluted silane mixed with H2-diluted silane or with O2 under various mixing ratios. The compositions of the layers of the films were measured with electron spectroscopy for chemical analysis (ESCA) along the depth from the film surface by Ar-ion etching. The results have revealed that O-atoms diffuse into and N-atoms diffuse out of the SiN
X
O
Y
layer during SiO
X
layer deposition. By making use of the relation between the refractive index and atomic ratio Si/O or O/N for SiN
X
O
Y
films, the gradual changes of the refractive index in the SiO
X
/SiN
X
O
Y
interfacial (or transition) region has been determined. As a result, the SiO
X
/SiN
X
O
Y
double-layer antireflective coating (ARC) has increased the short circuit current density of single-crystal Si solar cells by about 56% in comparison to bare cells.
Field-Induced Junction in InSb Gate-Controlled Diodes
Authors: Lan W. H. , Tu S. L. , Cherng Y. T. , Pang Y. M. , Yang S. J. , Huang K. F.
Published: February 2005

InSb gate-controlled diodes were fabricated to study breakdown behavior and surface effects. I-V characteristics were measured as a function of gate voltage and temperature. The results indicated that a field-induced junction was formed as the negative bias exceeded -4 V. The field induced junction was found to have a breakdown voltage smaller than that of the metallurgical junction. Saturation of the breakdown current in the field-induced junction was also observed, which could be explained by the conducting channel effect similar to that in the metal oxide semiconductor field effect transistor (MOSFET). The reverse current was also measured as a function of temperature to study the leakage mechanism. The strong exponential temperature dependence suggested that the reverse current was dominated by the G-R mechanism.
Crystalline Orientation Control for Bi-Sr-Ca-Cu-O Thin Films Prepared on (110)SrTiO3 by Coevaporation
Authors: Ishizuka Yoshiki , Yoshiaki Terashima Yoshiaki Terashima , Tadao Miura Tadao Miura
Published: February 2005

Superconducting Bi-Sr-Ca-Cu-O thin films were prepared on (110)SrTiO3 substrates by coevaporation with an rf oxygen plasma. Four orientation categories were observed, the 2223-phase (119) orientation, the 2212-phase (119) orientation, the 2212-phase (117) orientation, and the 2212-phase (00n) orientation. It has been confirmed that these orientations can be controlled by changing the rf oxygen plasma conditions. The (00n) orientation grew as the oxygen flow rate increased or as the rf power increased.
Dose and Damage Measurements in Low Dose Ion Implantation in Silicon by Photo-Acoustic Displacement and Minority Carrier Lifetime
Authors: Washidzu Gen , Hara Tohru , Ichikawa Ryuji , Takamatsu Hiroyuki , Sumie Shingo , Nishimoto Yoshiro , Nakai Yasuhide , Hashizume Hidehisa , Miyoshi Tsunemichi
Published: February 2005

Photo-acoustic displacement (PAD) generated with a modulated laser beam pumping is studied for As+ or B+ implanted Si. At doses above 1×1013 ions/cm2, the PAD has a close relationship to damage density. An ion implantation dose down to 2×109 ions/cm2 can be detected by the PAD measurement. Doses below 2×1010 ions/cm2 can be monitored by minority carrier lifetime measurement. A non-destructive high-sensitive dose monitor can be achieved by the PAD and minority carrier lifetime measurements. This monitoring leads to tight control of the threshold voltage of a MOS transistor.
Selective Area Growth of InP and InGaAs Layers on SiO2-Masked Substrate by Chemical Beam Epitaxy
Authors: Sugiura Hideo , Iga Ryuzo , Toriyama Takeshi Yamada
Published: February 2005

Selective area growth of InP or InGaAs single layers and their superlattices has been studied. Increasing substrate temperature suppresses the formation of polycrystal grains on stripe masks. No deposition of the polycrystals occurs on 40-µm-wide masks above 510°C for InP and above 540°C for InGaAs. Secondary electron microscopy and cathode-luminescence (CL) spectroscopy of the superlattice reveal that layer thicknesses and CL peak wavelengths are uniform across the unmasked area, except in the vicinity of mask edges. The mechanism of selective growth is also discussed.
Superconductivity in Hydrogen-Doped Nd1.85Ce0.15CuO4
Authors: Kobayashi Kenkichiro , Goto Yoshiharu , Shigenori Matsushima Shigenori Matsushima , Genji Okada Genji Okada
Published: February 2005

Hydrogenation of Nd1.85Ce0.15CuO4 has been carried out at a low temperature of 110°C in 1 atm H2. The contents of hydrogen and oxygen of H-doped samples are estimated by pulse H-NMR measurements and thermogravimetric analysis. The T
c values of H-doped samples are independent of the hydrogen content, whereas the volume fraction of superconductivity is significantly decreased with the increase in hydrogen content. These results are explained by the local disappearance of superconductivity in the neighborhood of a doped hydrogen atom.
A New Non-Cu-Oxide Superconductor: (Sr1-xLnx)Nb2O6-y (Ln: La, Nd, Pr and Ce)
Authors: Akimitsu Jun , Amano Jiro , Sawa Hiroshi , Nagase Osamu , Kazuhiro Gyoda Kazuhiro Gyoda , Manami Kogai Manami Kogai
Published: February 2005

A new non-Cu superconductor (Sr1-x
Ln
x
)Nb2O6-y
(Ln: La, Nd, Pr, Ce, Gd and Ho) has been found through resistivity and magnetization measurements. The highest onset transition temperature is about 12 K. Preliminary electron and X-ray diffraction experiments indicate that the crystal structure of the system is orthorhombic with a unit cell of a=11.00 Å, b=7.68 Å and c=5.59 Å, suggesting that the basic crystal structure is an oxygen-deficient CaTa2O6-type structure.
Electrochemical Preparation of an Insulating Thin Film and Its Characterization
Authors: Kawai Tsuyoshi , Takao Kuwabara Takao Kuwabara , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

Electrochemical oxidation of 1,4-bis(2-methylstyryl)benzene has been performed. The oxidation current of the monomer was decreased with increasing number of cycles. The thickness and the conductivity of the electrochemically deposited film were as low as 0.1 µm and 7×10-14 S·cm-1, respectively. The capacitance of a metal-insulator-metal (MIM) capacitor in which the pinhole-free polymer film was used as a dielectric layer was also investigated.
Easy and Direct Measurement of Scattering Coefficients in the Microwave Junction by Injection of Wave Packet
Authors: Kunizo Ohkubo Kunizo Ohkubo
Published: February 2005

A simple method for measurement of scattering coefficients in the microwave junction without matched termination is described. The method is based on the observation of incident, reflected and scattered waves when an RF wave packet is injected for the microwave junction. The application of the method to the multijunction grill for driving the plasma current is presented with comparison to its theoretical prediction.
Improvement of Photoluminescence Properties of ZnSe Film Grown by Hydrogen Radical-Enhanced Chemical Vapor Deposition Using Alternate Gas Supply and Substrate Bias Application
Authors: Gotoh Jun , Shirai Hajime , Jun-ichi Hanna Jun-ichi Hanna , Isamu Shimizu Isamu Shimizu
Published: February 2005

High-quality ZnSe films were successfully grown on GaAs (100) at low temperatures, 200°C or lower, by hydrogen radical-enhanced chemical vapor deposition (HRCVD). Defects were markedly eliminated by the following factors: selection of source materials, avoidance of ion bombardment, and suppression of formation of adducts by alternate gas supply.
High-Quality YBa2Cu3O7-x Ceramics Prepared from Freeze-Dried Nitrates
Authors: Ito Toshimichi , Yoshitaka Kimura Yoshitaka Kimura , Akio Hiraki Akio Hiraki
Published: February 2005

Using fine powders prepared by a freeze-drying process of a nitrate solution, a YBa2Cu3O7-x
superconductor has been successfully formed in a ceramic plate. The other processes employed are two heat treatments, a flash decomposition of the freeze-dried nitrates and a subsequent calcination. It has been found that the formation of high-quality ceramics requires ∼10% of the Cu nitrate to be added to the stoichiometric nitrate solution as a starting material of the freeze-drying process. The ceramics thus obtained have the characteristics of a very dense structure with large grains and exhibit magnetic properties as a high T
c superconductor as good as those of a monocrystalline YBa2Cu3O7-x
.
Gamma Irradiation Effect on a Bi1.5Pb0.5Sr2Ca2Cu3O10 Superconductor
Authors: Shiraishi Kensuke , Yano Koichi , Otoguro Yasuo
Published: February 2005

A Bi1.5Pb0.5Sr2Ca2Cu3O10-y
ceramic was sequentially irradiated with 60Co γ-rays of 1.5 MR·h-1 in dose rate up to a dose of about 50 MR at ambient temperature, and the electrical resistivity was measured as a function of temperature. The critical superconducting transition temperature of 103.4 K increased to 104.1 K at 20.25 MR, and then decreased at a rate of 2.0×10-2 K/MR on further irradiation. Concurrently, the electrical resistivity at 300 K increased almost linearly with a rate of 0.1 µQ·m/MR in the dose range of about 2 to 20 MR, and the resistivity was little changed by the irradiation to about 37 MR.
Temperature-Dependent Irreversibility Magnetic Fields of High-Tc Superconducting BiPbSrCaCuO Tapes in the Magnetic Flux Densities up to 30 T in the Temperature Range from 33 to 90 K
Authors: Hikata Takeshi , Iwasa Ken-ichi Sato
Published: February 2005

Temperature-dependent irreversibility magnetic fields, H
irr(T) were measured for four samples of silver-sheathed Bi1.8Pb0.4Sr2Ca2.2Cu3O
x
tapes having 3 levels of zero-field, 77 K critical current density, J
co, in magnetic flux densities up to 30 T and in the temperature range from 33 to 90 K. The measurements were performed for two orientations of the tape plane, the plane parallel to the applied magnetic field direction and that perpendicular to the applied field. The measurements show that H
irr increases with J
co, implying that H
irr is strongly dependent on the morphology of the superconductors. H
irr was obtained at 27.9 T and 54.7 K for the sample with J
co=298 A/mm2 at 77.3 K.
Pr3+-Doped Superfluorescent Fluoride Fiber Laser
Authors: Ohishi Yasutake , Terutoshi Kanamori Terutoshi Kanamori , Shiro Takahashi Shiro Takahashi
Published: February 2005

A Pr3+-doped superfluorescent fluoride fiber laser operating in the 1.3 µm band is reported. An output power of 0.166 mW is obtained. The peak wavelength of superfluorescence is 1.306 µm which corresponds well to the central wavelength of optical telecommunication trunk line systems.
Effect of Molecular Structure of Chiral Fluorinated Compounds on Spontaneous Polarization of Ferroelectric Liquid Crystals
Authors: Koden Mitsuhiro , Shiomi Makoto , Nakagawa Kenichi , Funada Fumiaki , Awane Katsunobu , Yamazaki Takashi , Kitazume Tomoya
Published: February 2005

The trans and cis isomers derived from chiral 1-trifluoromethyl-3-phenyl-2-propen-1-ol were prepared as chiral dopants of ferroelectric liquid crystals. They were doped to an achiral compound possessing a smectic C phase, and the induced spontaneous polarization of the mixtures was investigated. The observed spontaneous polarization for the trans isomer is larger than that for the cis isomer. The signs and values of spontaneous polarization were explained by a model which examined the fitness of two typical conformers possessing positive and negative spontaneous polarization to the zigzag conformation of molecules in the smectic C phase.
Crystal Structure of New Compounds, Cu6O8Cu2X (X=Cl, NO3)
Authors: Hayakawa Hiroshi , Akiba Etsuo , Ihara Hideo , Shuitiro Ono Shuitiro Ono
Published: February 2005

Crystal structure analyses of new compounds, Cu6O8Cu2X (X=Cl, NO3), have been carried out using the X-ray powder pattern fitting method (Rietveld method) together with thermal analyses. Although these compounds have a face-centered cubic structure analogous to that of Cu6O8InCl previously reported with a space group of Fm3̄m, the Cu2 (24e site) ions have a quite different configuration from that of the corresponding In ion. From the results of the above-mentioned analyses together with chemical analyses, the compositions of these samples were obtained as Cu5.7O8Cu1.9Cl0.69(NO3)0.31 and Cu5.7O8Cu1.9NO3, respectively. The unit cell parameters are a=9.376(1) Å for the former and 9.481(1) Å for the latter. These compounds decompose to CuO at 400°C and 350°C, respectively.
Influence of Water Treatment of LaF3 Crystal on LaF3-Based Oxygen Sensor Workable at Room Temperature
Authors: Lukaszewicz Jerzy P. , Norio Miura Norio Miura , Noboru Yamazoe Noboru Yamazoe
Published: February 2005

The effects of a water treatment of the LaF3 single crystal on an LaF3-based oxygen sensor were investigated. It was found that the oxygen-sensing properties were significantly affected by the water treatment depending on the perovskite-type oxides (LaCrO3, LaCoO3, La0.8Ca0.2MnO3) used as the sensing electrode material and the duration of the treatment. As revealed by XPS, the treatment induced the incorporation of oxygen in the surface region of the LaF3 crystal, leading to an increase in the number of electrons of the electrochemical reduction of oxygen from 1 or 2 to 4.
Effect of Etching Condition on the Formation of Bioactive Surface of Hydroxyapatite-Glass-Titanium Composite
Authors: Ban Seiji , Maruno Shigeo , Jiro Hasegawa Jiro Hasegawa
Published: February 2005

X-ray diffraction study shows that an etching solution of 3% HF and 5% HNO3 is the most suitable solution for preparing a bioactive surface layer of HA-glass-titanium composite, since the glass is removed, a great number of HA particles are exposed, and little CaF2 is produced by the etching. Anodic polarization measurement demonstrates that the 3-min etching gives an electrochemically active surface of the composites. These results and SEM observations suggest that this solution provides an adequate surface of the composite for the dental and medical implants.
A Monte Carlo Supercell Approach for the Effects of Disorder on the Upper-Valley Electronic Properties in InGaAs Ternary Alloys
Authors: Yamaguchi Naoteru Shigekawa
Published: February 2005

We propose a novel approach (Monte Carlo supercell approach) for investigating the effects of disorder on the upper-valley electronic properties in an InGaAs ternary alloy. In this approach, the electronic properties in supercells with random atomic configurations are analyzed using the s
p
3
s
* tight-binding method. Effects of the bond-length difference in the alloy are considered in the present analysis. The effects of disorder on the upper-valley electronic properties have been evaluated by examining the spectral function. The disorder-limited upper-valley electron relaxation time obtained from the spectral function is much shorter than that due to the intervalley-phonon scattering, which indicates that the disorder in the InGaAs alloy induces strong effects on the electron transport properties in high electric fields.
Importance of Charged Dangling Bonds in Explaining the Photodegradation Behavior of Amorphous Silicon Films Prepared by Various Techniques
Authors: Peter J. McElheny Peter J. McElheny , Akihisa Matsuda Akihisa Matsuda
Published: February 2005

The assumption that the photodegradation of the coplanar conductivities in amorphous silicon films is a direct consequence of the increase in the number density of neutral dangling bonds was found to be invalid. A model based on the importance of charged dangling bonds was proposed. Through the use of this model, it was shown that the films prepared by the Xe-dilution method, which show a slight increase in the photoconductivity concurrent with an increase in the number density of neutral dangling bonds, preferentially reconfigure positively charged dangling bonds into neutral dangling bonds upon exposure to light.
A Theoretical Investigation of the Metastability of Epitaxial Zinc-Blende CdSe on (100) Zinc-Blende Substrate
Authors: Tomonori Ito Tomonori Ito
Published: February 2005

The metastability of zinc-blende (cubic) CdSe on (100) zinc-blende substrate is discussed based on cohesive energy calculations for bulk form and thin layers of CdSe using the pseudopotential perturbation approach and universal empirical potentials. In the bulk form, zinc-blende CdSe is found to be less stable than wurtzite CdSe by 10 (meV/atom). However, the wurtzite CdSe on the (100) zinc-blende ZnTe substrate is destabilized because of a large deviation in the atomic coordination number at the wurtzite/zinc-blende interface from the ideal coordination number Z=4 for tetrahedrally bonded semiconductors, which leads to a higher energy of 500 (meV/atom) compared to that at a zinc-blende/zinc-blende interface. Theses findings suggest that zinc-blende CdSe can be grown on the (100) zinc-blende substarate.
Comparison between Powder-Pressed and Melt-Processed Bulk Superconductor Lenses (Supertrons) for Electron Beams
Authors: Matsuzawa Hidenori , Miyamoto Toshiyuki , Chino Yukio , Fukutake Eiji , Osada Tomoaki , Yoshiharu Ishibashi Yoshiharu Ishibashi , Tetsuya Akitsu Tetsuya Akitsu
Published: February 2005

To confirm a model for operation of powder-pressed bulk superconductor lenses (Supertrons), Y-based quench-melt-growth (QMG) bulk superconductors were used to focus intense electron beams (340 keV, ∼1 kA, and 5∼10 ns). The lens focused the beams much less effectively than any of the Y-, Bi-, and Tl-based powder-pressed bulk lenses and even worse than a copper-made lens. These facts support the validity of the model in which powder-pressed bulk superconductors behave like ferrite cores at frequencies of some hundred MHz.
Optical Second- and Third-Harmonic Generations in C60 Film
Authors: Hoshi Hajime , Nakamura Naoki , Maruyama Yusei , Nakagawa Takashi , Suzuki Shinzo , Shiromaru Haruo , Achiba Yohji
Published: February 2005

Optical second- and third-harmonic generations in C60 film have been studied using a Nd:YAG laser as the fundamental light source. Observed dependences of the generated second- and third-harmonic intensities on the polarization of light and on the angle of incidence are discussed based on the symmetry of the film structure. The relatively large third-order nonlinear response of ||
χ(3)(-3ω; ω, ω, ω)||
≃2×10-10 esu has been observed.
Refractive Index and Microscopic Studies of Polymer Dispersed Liquid Crystal Films Containing Low Concentration of Liquid Crystals
Authors: Deeleep K. Rout Deeleep K. Rout , Sukhmal C. Jain Sukhmal C. Jain
Published: February 2005

Refractive index and Microscopic studies of polymer dispersed liquid crystals (PDLCs) containing low concentration of liquid crystal (LC) have shown that LC forms solution with the polymer matrix and modify its basic properties considerably. A minimum amount of LC (dependent on polymer and temperature) needs to be added to the polymer matrix for its effective phase separation to occur and to render good scattering properties to PDLC films. It has also been observed that microdroplets are not stable above the softening temperature of the polymer.
Stable Potential Oscillation of Lipid Membrane Supported by a Micropore
Authors: Sha Seimei , Abatti Paulo Jose , Iko Kazuhiro , Takamichi Nakamoto Takamichi Nakamoto , Toyosaka Moriizumi Toyosaka Moriizumi
Published: February 2005

A rhythmic, sustained, stable potential oscillation was reproducibly observed for a lipid membrane supported by a micropore of a thin membrane tip micropipette. Amplitude and period of the oscillation voltage was controlled by changing the pore diameter. The relationship between oscillation period and pore diameter when the pore diameter was below 8 µm was different from that when the diameter was larger than 8 µm.
Epitaxial Growth of Ba1-XKXBiO3Thin Films by High-Pressure Reactive RF-Magnetron Sputtering
Authors: Takahashi Kazuhiko , Iyori Masahiro , Kamino Maruo , Usuki Tatsuro , Yorinobu Yoshisato Yorinobu Yoshisato , Shoichi Nakano Shoichi Nakano
Published: February 2005

Epitaxial growth of Ba1-XKXBiO3(110) thin films has been carried out on SrTiO3(110) substrates using reactive rf-magnetron sputtering for the first time under a 80 Pa discharge gas which is of a rather higher pressure than is usual. Electrical measurements showed thatTcof as-grown films was 16 K. A preferred orientation of (110) and epitaxial growth of the Ba-K-Bi-O film on the substrates were confirmed by XRD (X-ray diffraction) and RHEED (reflection high-energy electron diffraction), respectively.
High Conducting Large Area Indium Tin Oxide Electrodes for Displays Prepared by DC Magnetron Sputtering
Authors: Latz R. , K. Michael K. Michael , M. Scherer M. Scherer
Published: February 2005

High conducting ITO films were deposited by DC magnetron sputtering using ITO targets. At substrate temperatures of 200°C and 300°C ITO films were reproducibly prepared with resistivities of 1.9×10-4 Ω·cm respectively 1,4×10-4 Ω·cm at a deposition rate of 20 Å/s. ITO films prepared at room temperature show after annealing at 200°C in air, nitrogen or vacuum the same low resistivity of 1.9×10-4 Ω·cm when using optimum sputtering conditions. The influence of the deposition temperature on the electrical, optical and etching properties was studied and related to the structure of the ITO films. Details on an optimized in line sputtering system for the economic large scale production of ITO films are presented.
Thermopower and Resistivity of 1212-Type Phase TlSr2(Er1-ySry)Cu2O7-δ
Authors: Xin Y. , Li Y. F. , Ford D. , D. O. Pederson D. O. Pederson , Z. Z. Sheng Z. Z. Sheng
Published: February 2005

Nominal TlSr2(Er1-y
Sr
y
)Cu2O
x
samples were prepared, and were investigated by powder X-ray diffraction analyses, and by resistivity and thermoelectric-power measurements. The samples with y=0.0-0.5 are nearly pure 1212-type phase TlSr2(Er1-y
Sr
y
)Cu2O7-δ. The 1212 phase converts from semiconducting to superconducting at y=0.1-0.2, and exhibits the optimal superconducting behavior when y=0.4-0.5. In the range of 150-300 K, the thermopower values of the 1212 phase are nearly temperature-independent. The hole concentration calculated from the thermopower data using the Hubbard model in high temperature limit with strong on-site Coulomb interaction is quantitatively consistent with the y/2 value.
Fabrication of Bi2Sr2Ca1Cu2O8+δ/Bi2Sr2Nd1Cu2O8+δ/Bi2Sr2Ca1Cu2O8+δ Josephson Junctions
Authors: Koichi Mizuno Koichi Mizuno , Kentaro Setsune Kentaro Setsune
Published: February 2005

Sandwich-type Josephson junctions using Bi-based oxide barriers were successfully fabricated. Bi2Sr2Ca1Cu2O8+δ films were used for superconducting electrodes, and Bi2Sr2Nd1Cu2O8+δ films were used for the barrier layers. Each material had the same crystalline structure. The resistivity values of the Bi2Sr2Nd1Cu2O8+δ films were rather high compared to those of ordinary metals or Bi2Sr2Cu1O6+δ. The junctions clearly exhibited S/N/S-type characteristics. We observed the ac Josephson effect on the I-V curves under the irradiation of microwaves around 12 GHz.
P-Type Carbon-Doped InGaAs Grown by Metalorganic Molecular Beam Epitaxy
Authors: Shirakashi Jun-ichi , Yamada Takumi , Qi Ming , Nozaki Shinji , Takahashi Kiyoshi , Tokumitsu Eisuke , Konagai Makoto
Published: February 2005

Carbon-doped In
x
Ga1-x
As layers (x=0∼0.96) were grown by metalorganic molecular beam epitaxy (MOMBE) using trimethylgallium (TMG), solid arsenic (As4) and solid indium (In) as sources of Ga, As and In, respectively. The growth temperature and the indium beam flux strongly affect carrier concentration, and the growth temperature also affects the indium molar fraction of the In
x
Ga1-x
As layers grown even with the fixed indium beam flux. The hole concentration decreases with increasing indium molar fraction from 0 to 0.8, and then the conduction type changes from the p to n type at x=0.8. Hole concentrations of 1.0×1019 and 1.2×1018 cm-3 are obtained for x=0.3 and 0.54, respectively. These values are significantly higher than those reported for carbon-doped In
x
Ga1-x
As by MBE.
Constant-Photocurrent-Method (CPM) Studies on Light-Induced Changes in Hydrogenated Amorphous Silicon
Authors: Sakata Isao , Yamanaka Mitsuyuki , Shoji Numase Shoji Numase , Yutaka Hayashi Yutaka Hayashi
Published: February 2005

A constant photocurrent method (CPM) has been adopted to study detailed mechanisms of light-induced changes in undoped hydrogenated amorphous silicon (a-Si:H). Defects other than neutral Si dangling bonds are generated in undoped a-Si:H by illumination for less than 20 hours, and these states control the photoconductivity of samples. Another type of defect state exists in the annealed state of a-Si:H whose density decreases with prolonged illumination, in contrast to a neutral Si dangling bond state. Possible origins of these defect states are discussed.
Characteristics of Bloch Line Pair Propagation with Cr Bit Pattern
Authors: Asada Hironori , Yamato Junichi , Satoru Ikeda Satoru Ikeda , Kimihide Matsuyama Kimihide Matsuyama
Published: February 2005

The artificial stress-induced anisotropy in a liquid phase epitaxial garnet film has been studied aiming at the application to a bit confinement pattern in Bloch line memory. The potential well for a vertical Bloch line (VBL) pair generated by the stress-induced anisotropy variation has been computed. VBL bit propagation is studied experimentally for a test chip with the stress-induced bit positions. The bit propagation was successfully performed under the Cr bit pattern with a periodic film thickness variation of 0.08 µm by applying the drive pulses with rise time shorter than 100 ns and fall time longer than 1000 ns.
A New High Electron Mobility Transistor (HEMT) Structure with a Narrow Quantum Well Formed by Inserting a Few Monolayers in the Channel
Authors: Matsumura Kohji , Inoue Daijiro , Nakano Haruo , Sawada Minoru , Yasoo Harada Yasoo Harada , Takashi Nakakado Takashi Nakakado
Published: February 2005

A new HEMT wafer has been developed whose channel layer has a narrow bandgap semiconductor with a few monolayers inserted at an optimum position in the channel, namely, the point where the probability density of electrons is maximum in the lowest subband and negligible in the first excited subband. The Al0.22Ga0.78As/In0.15Ga0.85As pseudomorphic HEMT wafer with one InAs monolayer inserted at the optimum position has provided Hall electron mobility increments nearly 15% higher at 300 K and 20% higher at 77 K than those of conventional pseudomorphic HEMT wafers.
Photoluminescence from GaAs/AlGaAs Quantum Wells Grown at 350°C by Conventional Molecular Beam Epitaxy
Authors: Sekiguchi Yoshinobu , Sei-ichi Miyazawa Sei-ichi Miyazawa , Natsuhiko Mizutani Natsuhiko Mizutani
Published: February 2005

Photoluminescence measurements have been carried out for GaAs/AlGaAs single quantum well (SQW) structures grown without interruption by conventional molecular beam epitaxy. The full widths at half-maximum (FWHM) from QWs having thin well width were reduced monotonously with the decrease of growth temperature until 350°C to one-half. This reduction of FWHM was explained by the transition of the top and bottom heterointerfaces which became close to the effective smooth interfaces at 350°C. The peak intensity had only a weak dependence on the growth temperature at the same temperature.
Photocrystallization of Cold Condensed Amorphous TlCl Films Detected by UV Absorption Measurements
Authors: Kondo Shin-ichi , Takaki Itoh Takaki Itoh , Mamoru Mekata Mamoru Mekata
Published: February 2005

Photocrystallization was found in the cold condensed amorphous TlCl films by UV absorption measurements under irradiation at 77 K with UV light of less than 80 µW·cm-2 intensity for 8 h. The photocrystallized films are of a microcrystalline nature characterized by the absence of the 1st exciton peak, but crystal growth occurs by annealing at room temperature and the sharp 1st exciton peak appears.
Self-Defocusing of Mode-Locked Nd:YAG Laser Radiation in GaAs, CdSe and InP
Authors: Kubecek Vaclav , Kumazaki Shigeichi , Takagi Yoshihiro , Reali Keitaro Yoshihara
Published: February 2005

Defocusing in GaAs, CdSe and InP of 25 ps pulse trains from an active-passive mode-locked flashlamp pumped Nd:YAG laser at 1.064 µm is investigated. The distortion of the train envelope and of the spatial beam profile induced by charge carriers created by two-photon absorption are observed at light intensities of 50-100 MW/cm2 for GaAs and CdSe and 25 MW/cm2 for InP. This different behavior is indicative of the different response of InP which is found to be not useful for passive negative feedback of mode-locked Nd:YAG lasers.
Anomalous Changes of Structural Parameters at Tc in the Superconductor Ba0.7K0.3BiO3
Authors: Ono Yasuhiro , Ken-ichiro Yamauchi Ken-ichiro Yamauchi , Noboru Yamada Noboru Yamada
Published: February 2005

We report the results of an X-ray scattering study of the structure of Ba0.7K0.3BiO3 as a function of temperature. We found that the lattice symmetry changes from cubic to tetragonal at about 250 K, and there is an anomaly in lattice constants near the superconducting transition. Furthermore, an abrupt change of an overall isotropic thermal parameter was found just at the superconducting transition. Our results suggest that the electron system strongly couples to the lattice system.
Photoluminescence in CuGaS2 Crystals Grown by Iodine-Transport Method
Authors: Miyazaki Toshiya , Sho Shirakata Sho Shirakata , Shigehiro Isomura Shigehiro Isomura
Published: February 2005

Low-temperature (4.2 K) photoluminescence (PL) measurements have been performed on CuGaS2 crystals grown from nonstoichiometric starting materials. The Cu-rich crystals showed several sharp zero-phonon lines at 2.397, 2.404 and 2.417 eV in contrast to the Ga-rich crystals showing the strong donor-acceptor pair emission at 2.4 eV. The origins of these PL peaks are discussed in terms of the native defects introduced by the deviation from stoichiometry.
Flux Pinning Characteristics in Tl Series Superconductors
Authors: Sasaoka Takaaki , Nomoto Akira , Seido Masahiro , Doi Toshiya , Kamo Tomoichi
Published: February 2005

Magnetic hysteresis and flux creep characteristics were measured with partially-melted Tl 1223 and solid-state-reacted Tl 2223 superconductors at 77 K. The Tl 1223 sample shows large magnetic hysteresis which linearly depends on sample thickness, and less time decay of magnetization, though the sample has many grain boundaries.
Plasma Oxidation of Copper Thin Films
Authors: Ito Wataru , Shimada Haruo , Muneyuki Imafuku Muneyuki Imafuku , Misao Hashimoto Misao Hashimoto
Published: February 2005

The sample current against the counterelectrode during the plasma oxidation process of copper thin films were measured and the oxidation mechanism was discussed combined with the obtained reaction products on the surface. The changes and the similarities of the sample current for the plasma oxidation of copper films and YBCO multilayered films were successfully explained. It was also found that the oxidation process proceeded at a temperature lower than that needed for construction of the YBCO structure, and there was still some amount of metallic copper remaining even in the case of high-T
c sputter-deposited YBCO films.
Dependence of Crystal Orientation of BiSrCaCuO Thin Films on Off-Angles of Vicinal SrTiO3 (110) Surfaces
Authors: Wada Osamu , Kuroda Ken'ichi , Tanimura Junji , Kataoka Masayuki , Kojima Kazuyoshi , Takami Tetsuya , Hamanaka Koichi , Tetsuo Ogama Tetsuo Ogama
Published: February 2005

Crystal orientation of BiSrCaCuO(11n) films depends on off-angles of vicinal SrTiO3(110) surfaces. Surfaces of SrTiO3(110) were cut 2°, 5° and 10° toward the [100] direction, and BiSrCaCuO thin films, which had a 2212 phase, were formed on these vicinal surfaces by RF magnetron sputtering. C-axes almost parallel to the [100] and [010] directions of the substrate were observed when the 2°- and 10°-off substrates were used, but only the c-axis parallel to the [010] was observed when the 5°-off substrate was used. These results suggest that there is an appropriate off-angle to obtain BiSrCaCuO thin films with the c-axis almost parallel to [010] only.
Van der Waals Epitaxial Growth of C60 Film on a Cleaved Face of MoS2
Authors: Sakurai Masatoshi , Tada Hirokazu , Koichiro Saiki Koichiro Saiki , Atsushi Koma Atsushi Koma
Published: February 2005

C60 film has been grown heteroepitaxially on a cleaved face of MoS2 by means of van der Waals epitaxy. The C60 film forms a close-packed structure with its principal crystal axes parallel to those of the substrate. Although the lattice constant of the C60 crystal is much larger than that of MoS2, good heteroepitaxial growth becomes possible because of the van der Waals-type interaction between the grown film and the substrate.
A Novel Method for Superconducting Energy Gap Measurement
Authors: Mizushima Koichi , Inoue Shinji , Masayuki Sagoi Masayuki Sagoi , Jiro Yoshida Jiro Yoshida
Published: February 2005

A novel method has been developed for the measurement of the superconducting energy gap in high-temperature superconductors. The energy gap was measured by detecting the quasi-particle current through an SNS' junction, where S and S' are a high-temperature and a conventional superconductor, respectively. The advantage of this method over conventional tunneling spectroscopy lies in its applicability to superconductors with a degraded surface. A clear gaplike structure with a gap energy of 16 mV was observed for YBCO.