bluuebunny/crossref_metadata_2025 huggingface dataset:
The Contact Resistance of the YBa2Cu3O7-δ-Metal Film System
Authors: Suzuki Yoshihiko , Kusaka Tadaoki , Aoki Akira , Aoyama Takahiro , Yotsuya Tsutom , Ogawa Soichi
Published: February 2005

The electrical properties and X-ray photoelectron spectroscopy (XPS) of Y1Ba2Cu3O7-δ (YBCO) contacts formed by Ag, Au, Sn, Zn, In and Al metal films have been studied. The Cu, In, Zn and Sn film contacts show high resistivities with semiconductive temperature dependence. The Au, Ag, and Pt film contacts have low resistivities with metallic temperature dependence. The XPS analyses show that Sn and Al react with the oxygen on the YBCO surface. However, little change in copper and oxygen states can be observed in Ag/YBCO and Au/YBCO systems. It is assumed that the oxygen-deficient layer at the interfaces of Sn/YBCO and Al/YBCO systems makes the contact resistance high, while the semiconductive layer is insignificant at the Ag/YBCO and Au/YBCO interfaces, and their resistance is low. Analyses indicate that Ag/YBCO and Au/YBCO systems provide very effective ohmic contacts.
Multivalence Resonance-Condensation Model for Electron Pairing and Superconductivity in High Tc Superconductors: A Possible Novel and Universal Origin of Superconductivity
Authors: Nakamura Akio
Published: February 2005

The multivalence resonance-condensation model (MVRC model) is suggested as a possible novel and universal origin of high T
c superconductivity and successfully applied to various high T
c oxide superconductors with perovskite-related structure, such as strongly anisotropic layered cuprates and almost isotropic bismuthates. The MVRC state is Bose condensation of the resonance hybrids between two kinds of multivalence states of the cations Cu1+, 2+, 3+(Bi3+, 4+, 5+, Pb2+, 3+, 4+, etc.) responsible for the superconductivity and is shown from its simple geometrical configuration on the actual crystal lattice planes to provide a unified picture of the superconducting state of all these systems in a consistent manner. Most importantly, the model reveals the inherent deep connection of superconductivity with the fundamental and universal nature of matter, i.e., the chemical bond. Thus, the model is expected to be a guiding chemical and structural principle in both the search for new superconductors and the construction of a new quantitative theoretical model.
A Simple Langmuir Trough for an Inverted Fluorescence Microscope
Authors: Miyano Kenjiro , Mori Akira
Published: February 2005

A simple Langmuir trough that can be fitted to a commercially available inverted fluorescence microscope has been designed and constructed. The trough allows in situ observation of a monolayer on water over a wide area. The space above the water surface is left open for manipulation of the monolayer. Examples of the utility of the apparatus are given.
Transition Process from Film Breakdown to Complete Breakdown in a Silicone-Oil/Polymer-Film Composite under Point-Cathode/Plane-Anode
Authors: Kitani Isamu , Kadowaki Kazunori , Arii Kiyomitsu
Published: February 2005

The purpose of this paper was to clarify the physical reason for the previously reported experimental results that a complete breakdown in a silicone-oil/PET-film composite for a negative point occurred after a considerable time had elapsed after the film breakdown due to charge deposition. It was concluded from some experiments that the breakdown in the composite was completed by a positive streamer propagation from the breakdown spot of the film which was induced by negative charges emitted from the point cathode immediately after the film breakdown. The minimum delay time between the complete breakdown and the film breakdown was approximately equal to the transit time of negative charges from the point cathode to the film.
Molecular Orientation and Photocurrent of Alkyl-Aromatic Polyimide Films Prepared by Vapor Deposition Polymerization
Authors: Iida Kazuo , Nohara Tsukasa , Totani Kazuyuki , Nakamura Shuhei , Sawa Goro
Published: February 2005

Vapor deposition polymerization by a coevaporation of pyromellitic dianhydride and decamethylenediamine monomers has been employed for the preparation of polyamic acid as a precursor for polyimide films. By curing at temperatures of 200–250°C the polyamic acid became the polyimide with directional arrangement of the molecular chain in the normal to the substrate observed by wide-angle X-ray diffraction. The sample containing a large amount of oriented crystals showed a small photocurrent. It was concluded that the oriented chain containing a decamethylene moiety hinders the carrier transfer between pyromellitimide moieties, resulting in a decrease of current.
An Experimental Study of the Vacuum Magnetic Surfaces of Heliotron E
Authors: Takahashi Ryukichi , Motojima Osamu , Obiki Tokuhiro , Nakasuga Masahiko , Mizuuchi Tooru , Iiyoshi Atuo
Published: February 2005

The structure of the vacuum magnetic surfaces of Heliotron E was studied numerically and experimentally. A pulsed electron beam method was used to map out the magnetic surfaces up to the rotational transforms of 1. An electron emissive probe method was adopted to investigate the position of the boundary. The experiments were performed under a reduced operation field of 500 G, where the geomagnetic field could not be ignored. The last closed magnetic surface agreed relatively well with the numerically calculated one. The rotational transform at the magnetic axis was found to be slightly less than 0.5. Results showed that Heliotron E has rotational transform profiles sensitive to the low-mode-numbered perturbation field.
An E-Beam Direct Write Process for 16M-Bit DRAMs
Authors: Nomura Noboru , Kawakita Kenji , Hirai Yoshihiko , Sakashita Toshihiko , Harafuji Kenji , Hashimoto Kazuhiko , Koizumi Taichi , Hamaguchi Hiromitsu , Misaka Akio , Takemoto Toyoki
Published: February 2005

For obtaining a very fine wafer pattern below half micron, direct write EB lithography has charging and proximity effect problems. A method of compensating for the charging problem is to use a 40 kV proton shower irradiation process which decreases the bottom layer resistance of the trilayer resist. The charge of the electron beam is dissipated through the bottom-layer resist.
As for the proximity effect, we developed a proximity effect correction software system by dosage modification. The theoretical and experimental results showed that in a 2.2-micron-thick trilayer planarizing resist system, a 0.5-micron isolated line, 0.5-micron isolated space, and 0.5-micron contact holes were simultaneously resolved in a half-micron-thick top-layer resist.
The resultant half-micron-rule 16M-bit DRAM patterns were successfully obtained on uneven topography of the processed wafer using EB direct write.
Modal Vibration Control of Large Ultrasonic Tools in High Amplitude Operation
Authors: Adachi Kazunari , Ueha Sadayuki
Published: February 2005

Practical problems concerning modal vibration control of large ultrasonic plastic welding tools using' wave-trapped horns' have been solved. First, to judge the instability of the vibration modes of interest in relation to changes in the horn lengths, the authors propose the instability coefficient' as a practical criterion. Secondly, it has been found that the undesirable influence of the large connecting screws necessary for high amplitude operation can be avoided by means of an appropriate choice of vibrating system configuration giving low values of the coefficient. Lastly, temperature stability of the modes is examined through computer simulations and theoretical consideration. The feasibility of the method is completely vindicated.
Electrical Switching in Evaporated Lead Phthalocyanine Films
Authors: Machida Yasuhiko , Saito Yukihiro , Taomoto Akira , Nichogi Katsuhiro , Waragai Katsunori , Asakawa Shiro
Published: February 2005

The switching characteristics of a sandwich cell having a Au-lead phthalocyanine-Au structure were studied. Switching was observed in a film which was evaporated at a rate of 10 Å/s and consisted of a mixture of grains of monoclinic structure and amorphous fraction. The presence of moisture was necessary for switching.
Soft X-Ray Emission Spectra of B K and Si L2,3 in B–Si–Ge Alloys
Authors: Imura Takeshi , Nakamura Hatsuo , Kohno Kenji , Iwami Motohiro
Published: February 2005

Valence band B K and Si L
2,3 soft X-ray emission spectra are measured for B–Si–Ge alloy films of both amorphous and microcrystalline forms to obtain information on the chemical bonding states of B and Si. The B K band spectra are similar to those of pure crystalline boron, although the linewidths are somewhat narrower. The Si L
2,3 spectrum is more discrete in the amorphous alloy film than in a reference sample of amorphous hydrogenated silicon. The local structure around the Si atom in the microcrystalline alloy turns out to be similar to that in the Si crystal.
Thermoanalytical Studies on Preparation Conditions of Superconducting YBa2Cu3O7-y
Authors: Sugai Tokuko , Oya Gin-ichiro , Imai Syozo
Published: February 2005

We studied the decarbonation process of a ternary mixture of Y2O3, BaCO3 and CuO or Cu2O by TG-DTA analysis to clarify the optimum condition for the preparation of YBa2Cu3O7-y
ceramics, which are superconducting above 90 K. We found that a narrow temperature region, 940∼950°C, is desirable for the decarbonation process. Furthermore, we observed an anomaly at ∼600°C in DTA curves of stoichiometric YBa2Cu3O7-y
ceramics and nonstoichiometric Y–Ba–Cu–O samples. From the strong correlation between the magnitude of this anomaly and the composition of the ceramics, the anomaly was attributed to the orthorhombic-tetragonal phase transition in the YBa2Cu3O7-y
phase. It was also found that the composition dependence of T
c of the ceramics correlates strongly with that of the magnitude of the anomaly.
As-Grown Preparation of Superconducting Epitaxial Ba2YCu3Ox Thin Films Sputtered on Epitaxially Grown ZrO2/Si(100)
Authors: Myoren Hiroaki , Nishiyama Yukio , Fukumoto Hirofumi , Nasu Hiroyuki , Osaka Yukio
Published: February 2005

High-T
c superconducting Ba2YCu3O
x
thin films have been epitaxially grown on Si(100) substrates with the epitaxially grown tetragonal ZrO2 or cubic yttria-stabilized zirconia (YSZ) as a buffer layer. The thin films were prepared by rf magnetron sputtering of the stoichiometric Ba2YCu3O
x
target below 700°C. An adequate positive substrate bias was necessary to ensure surface smoothness and to show the superconducting transition above liquid nitrogen temperature without any post-treatment. The highest T
c(onset) and T
c(end) observed were 88 K and 84 K, respectively.
Deposition of Amorphous CoZrNb Films Using CMF Magnetron Sputtering Technique
Authors: Takahashi Takakazu , Yoneda Masaaki , Naoe Masahiko
Published: February 2005

Amorphous CoZrNb films with high saturation magnetization 4πMs of about 14 kG and low coercivity Hc of about 0.3 Oe have been successfully prepared by the CMF magnetron sputtering technique with a CoZrNb alloy target. Hc and 4πMs along the easy axis were changed by background pressure, film thickness and Ar pressure P
r. The applied voltage of discharge operation is as low as 270 V at P
r of 0.3 Pa. The maximum deposition rate is as large as 0.13 µm/min for a power density of 4.42 W/cm2. The target utilization efficiencies are improved in spite of using a magnetic target because a leakage magnetic field increases more to a greater extent by attaching an outer pole piece. These are about 95% and 60% in surface area and in volume, respectively. The changes in a film thickness of 1 µm deposited on the substrate were 0.05 µm at P
r of 0.2 Pa, and 0.06 µm at a distance of 50 mm between substrate and target, respectively.
Main Electron Traps in In1-xGaxP (0.12≤ x ≤ 0.96)
Authors: Matsumoto Takashi , Kato Takamasa , Takiguchi Minoru , Ishida Tetsuro
Published: February 2005

Deep level transient spectroscopy (DLTS) measurement has been made on solution-grown Te-doped In1-x
Ga
x
P alloys with 0.12 ≤ x ≤0.96. Three main electron traps, SGE1, SGE2 and SGE3, were detected. Their activation energy of carrier emission, E
T, were about 0.17, 0.40 and 0.45∼0.60 eV, respectively. SGE1 was detected in samples with x \lesssim 0.83, SGE2 in samples with x \gtrsim0.56 and SGE3 was detected in all samples examined. The peak of the DLTS spectrum of SGE2 moves to lower temperatures as the filling pulse width, t
p, is increased; and E
T derived from the Arrhenius plot depends on t
p.
Electrical Charging Characteristics of Spherulitic Polypropylene
Authors: Saito Nobuo , Ikezaki Kazuo
Published: February 2005

Surface potential and thermally stimulated currents (TSC) were examined for negatively corona-charged spherulitic polypropylene (PP) which was isothermally crystallized at 140°C for 2 or 4 hours from the 190°C melt of PP. It was found that the surface potential of the 4 hours-crystallized PP containing many large spherulites was limited to below about -900 volts. However, untreated PP and the 2 hours-crystallized spherulitic PP showed no surface potential saturation up to -1800 volts, which is the limit of the charging apparatus used in this study. From the results on the TSC of these samples, their surface potential saturation can be explained in terms of decrease in the number of charge trapping sites which are located in the interspherulitic amorphous regions of these samples. It was also demonstrated that the internal structure of spherulites did not contribute significantly to the charging saturation of spherulitic PP.
Optical Second-Harmonic Generation of Ammonium Fluoroberyllate Crystal in the Incommensurate and Ferroelectric Phases
Authors: Uesu Yoshiaki , Yamane Katsutoshi , Strukov Boris A.
Published: February 2005

Temperature dependence of the optical second-harmonic intensity of ammonium fluoroberyllate crystal (NH4)2BeF4 in the incommensurate and ferroelectric phases, and temperature dependence of coherence lengths in the ferroelectric phase were precisely measured. Strong second-harmonic intensity was not observed in the incommensurate phase, contrary to a previous report on the same type of crystal. Measured coherence lengths were compared with the incommensurate modulation period determined by the X-ray diffraction method. It was found that the coherence lengths were larger than the modulation period by a factor of 103. These facts indicate that the possibility of quasi-phase matching, i.e. the coincidence of the coherence length and the modulation period, is excluded in the crystal.
Temperature Dependence of Electrostriction in Lead Zinc Niobate
Authors: Sada Tohru , Umezawa Chieko , Uchino Kenji
Published: February 2005

Precise measurement of the temperature dependence of electrostriction has been carried out on single crystal samples of Pb(Zn1/3Nb2/3)O3 below and above the Curie temperature using a newly developed sample holder The polarization-related electrostrictive Q coefficients decrease gradually with an increase in temperature, and do not exhibit any significant changes around the average Curie Temperature of 130°C. The Q coefficients determined near 160°C are as follows: Q
11=3.43 ×10-2[m4C-2], Q
12=1.52×10-2 [m4C-2], and Q
44=1.74×10-2[m4C-2].
The Pressure Control System for a Liquid Deuterium Target
Authors: Ishikawa Katsumi , Kishida Takashi , Kuze Masahiro , Sai Fuminori , Tsuboyama Toru , Yamamoto Sukeyasu S. , Maki Takashi , Suzuki Shoji
Published: February 2005

A fine pressure control system utilizing a commercially available simple and inexpensive light intensity control circuit kit for a liquid deuterium target is described. The difference between the liquid deuterium vapor pressure and the atmospheric pressure can be controlled to much better than 0.001 kg/cm2 or equivalently the liquid deuterium density can be kept constant at 0.1626±0.0003 g/cm3.
Transition and Reignition of Arc Discharge at Atmospheric Pressure
Authors: Nobata Kanehiro , Kurokawa Masaaki
Published: February 2005

The dynamic properties of an arc discharge have been experimentally studied. The arc transition occurs even with a small voltage between two electrodes to form a new arc path which is made by the advance of electrons from the cathode to the anode. And a reignition voltage against a residual current is obtained. That reignition occurs in two different forms. One directly develops to an arc discharge and the other develops through the formation of a glow discharge. Furthermore, we have discussed a condition on which the reignition occurs in a very short time.
Properties of Shell-Confined Long Life Plasmas Produced by Lasers
Authors: Daido Hiroyuki , Nishihara Katsunobu , Mima Kunioki , Yamanaka Masanobu , Endo Takuma , Shiraga Hiroyuki , Kato Yoshiaki , Miura Eisuke , Kitagawa Yoneyoshi , Yamanaka Chiyoe , Hasegawa Akira , Nakai Sadao
Published: February 2005

We report the generation of long-life plasmas confined by the heavy shell surrounding a plasma produced by lasers. We also demonstrate the neutron production from shell-confined carbon-deuterium plasmas using a GEKKO XII glass laser system at 1.05 µm and 0.53 µm wavelengths. A maximum neutron yield of more than 108 per shot without an implosion was obtained. Analyzing these results with the hydrodynamic simulation code, we propose the required conditions for demonstrating magnetic thermal insulation observed by the neutron measurement.
Collapse of Localized RF Electrostatic Field in Large Amplitude Cavitons in a Plasma Waveguide
Authors: Kato Keizo , Kunishima Akihiro , Minami Kazuo
Published: February 2005

Large amplitude cavitons caused by incident high-power microwave pulses with a frequency of 2.85 GHz up to 100 kW at the resonance plane are observed in a TM01 cylindrical plasma waveguide. The localized RF electrostatic fields are found to be attenuated by the action of wave breaking, and the dips of the density continue to grow. The dependences of the density profile of cavitons, the wave breaking time and the localized RE electrostatic fields at the breaking time on the incident power are consistent with the theoretical prediction, even for such high powers. The characteristics of Langmuir probe measurements after the initiation of the incidence of microwave pulses are also described.
Effect of Potentiostatic Control on in situ STM Images of Ag and Au Electrodes in a 0.1 M KCl Solution
Authors: Morita Seizo , Okada Takao , Mikoshiba Nobuo
Published: February 2005

We investigated the in situ STM images sequentially at the same places of Ag and Au electrodes in a 0.1 M KCl solution, as a function of a potentiostatic voltage. For the Ag electrode, by decreasing the potential, we found that the surface corrugation of the electrode varies suddenly from a flat to a rough surface around the calculated equilibrium potential of AgCl formation/reduction processes. We also found another phenomenon whereby the surface of the Ag electrode becomes more and more smooth with decreasing potential. We supposed this phenomenon to be a rearrangement of the Ag surface caused by the desorption of Cl- specific adions from the active sites. We also found that the roughness of Au surface depends on the potentiostatic voltage. This result seems to be related with the anodic dissolution/reduction processes and the desorption of Cl- specific adions.
Equilibrium Configuration of a High-Beta Screw Pinch
Authors: Hayase Kiyoshi
Published: February 2005

The magnetohydrodynamic equilibrium of a moderately elongated screw pinch is considered. From comparisons of experimental and calculated data on the elongation factor and radial shift of the plasma column, the configuration is described by a two-region flat-current tokamak model. The inner high-beta plasma is surrounded by a force-free current region.
A Small-Distortion and Low-Cost Stark Modulator for Laser Stark Modulation Spectroscopy
Authors: Okude Shin'ichiro
Published: February 2005

A small-distortion and low-cost Stark modulator is developed by newly adopting class-AB amplification in a trasformer-coupled voltage amplifier. Through analysis of the operation, clear guidelines for the design and tuning of the Stark modulator are found. The circuit paramenters for operations of output voltages 3 kV and 800 V (peak-to-peak) at 100 kHz and 2 MHz, respectively, are shown.
Nature of Localized States in Hydrogenated Si–Based Amorphous Semiconductor Films Elucidated from LESR and CPM
Authors: Shimizu Tatsuo , Kidoh Hideo , Morimoto Akiharu , Kumeda Minoru
Published: February 2005

Measurements of low energy absorption by the constant photocurrent method, ESR and light-induced ESR were carried out for a-Si:H, a-Si1-x
C
x
:H, a-Si1-x
O
x
:H and a-Si1-x
N
x
:H films as a function of the film thickness. As a result, both the surface density of dangling bonds in the disordered surface layer and the density of dangling bonds in the bulk region were obtained by discriminating between neutral and charged dangling bonds. It is found that many charged defects are present even in high-purity a-Si:H films and their density increases with the addition of O and N. We attribute these charged defects to Si3
-+N4
+ in a-Si1-x
N
x
:H, in contrast to the model of Robertson and Powell, and to Si3
-+O3
- in a-Si1-x
O
x
:H.
Study of Optical Pulse Compression with Higher-Order Nonlinearity and Dispersion
Authors: Kubota Hirokazu , Nakazawa Masataka
Published: February 2005

Propagation of ultrashort pulses in single-mode fibers, which involves a third-order dispersion and a self steepening effect (optical shock), have been studied to obtain femtosecond pulses with a grating pair pulse compressor. These effects cause asymmetrically broadened and nonlinearly chirped optical pulses, which degrade the characteristics of the pulse compression. These effects can be partially compensated for and the compressed pulse width can be reduced by using a third-order term of the phase function of the grating pair.
Phase Transition of Lipid Multilamellar Aqueous Suspension under High Pressure V. Ultrasonic Measurements in Temperature Range from 4th Transition to Main One under High Pressure
Authors: Utoh Shigenori , Takemura Tetuo , Oyama Tomo-o
Published: February 2005

The ultrasonic velocity and absorption at single 5 MHz of the DPPC multilamellar containing 25 wt.% water in the temperature range from the 4th transition to the main one have been investigated under several pressures up to about 300 MPa. Four phase transitions were measured as follows: (1) A fluctuation of the DPPC bimembrane density in the vicinity of the main transition point was strongly restricted due to the effect of pressure, and an extremely unsymmetrical form of the absorption peak around the main transition with an increase in pressure beyond 150 MPa was observed, (2) the notable appearance of the absorption peak in the pretransition under 250 MPa was observed although no absorption peak could be detected under pressure of less than 250 MPa, and (3) the changes of the ultrasonic velocity and bulk modulus corresponding to the sub- (or melting-like behavior) and 4th transition were observed distinctly under 295 MPa.
Crystal Structures of BaBiO3-x at High Temperatures
Authors: Kusuhara Hiroyuki , Yamanaka Atsushi , Sakuma Hiroshi , Hashizume Hiroo
Published: February 2005

High-temperature crystal structures of BaBiO3-x
(x=0∼0.2) were studied by in-situ neutron and X-ray powder diffraction techniques using controlled oxygen pressures. Rietveld profile analysis of the neutron data from BaBiO3 at 900 K has revealed that the structure is cubic with large anisotropic thermal vibration amplitudes of the O ions perpendicular to the Bi–O bonds. For oxygen-deficient BaBiO3-x
, both the neutron and X-ray data showed that the system is not a single phase. The X-ray data from BaBiO2.99 at 1010 K indicated a two-phase system comprising a cubic perovskite and a tetragonal structure with a doubled cell. Profile analyses gave refined cell parameters of a=6.293 and c=9.054 Å for the tetragonal phase. In more reduced BaBiO2.8 at 1075 K this tetragonal structure was replaced by another pseudotetragonal structure with a slightly expanded cell.
Lateral Growth of GaAs over SiO2 Films Prepared on (111)B Substrates by Metalorganic Chemical Vapor Deposition
Authors: Yamaguchi Ko-ichi , Okamoto Kotaro
Published: February 2005

Lateral growth of GaAs was carried out over SiO2 films on (111)B substrates by metalorganic chemical vapor deposition (MOCVD). A maximum growth rate of 0.29 µm/min was obtained at a direction having a 6° off-angle from < 110 > to < 112 >A, and the ratio of lateral to vertical growth rate was 48.3. When the direction of lateral growth deviated toward the <112>B side, the growth rate drastically decreased and the crystal-orientation dependence of the lateral growth rate could be explained by the off-angle dependence of the stability of the Ga kink site. The (11̄0) facet appearing on the growth front of lateral layers extending in the [11̄0] direction was extremely flat and perpendicular to substrate surface.
Effective Nuclear Charge and Chemical Shifts in X-Ray Absorption Spectra of Polymeric Copper(II) Salicylhydroxamates
Authors: Khadikar Padmakar V. , Mangelson Nolan F. , Pandharkar Sadhana P.
Published: February 2005

Edge shifts,ΔE, and effective nuclear charges,Zeff, for several polymeric copper(II) complexes of salicylhydroxamic acids have been estimated from copper K-absorption discontinuity using a 40 cm curved crystal spectrograph. The shifts show a parabolic dependence on the effective atomic charge,Zeff, of copper, indicating that an expression of the typeΔE=aZeff+b(Zeff)2, whereZeffis the effective atomic charge on the atom in a binary compound, is equally applicable to the complex systems. Finally, the XANES is analyzed critically in terms of edge shifts as well as of effective nuclear charge. Increase of the edge shift due to metal-metal interaction is not observed in the present case.
Preparation of Polypyrrole Film from Vapor Phase and Its Electrical Properties
Authors: Asano Mitsuharu , Inoue Masumi , Takai Yoshiaki , Mizutani Teruyoshi , Ieda Masayuki
Published: February 2005

Polypyrrole film was prepared using iodine vapor. Spectroscopic measurements revealed that the polypyrrole film mainly consisted of a chain structure of pyrrole units, but that it contained some saturated pyrrolidine units, partially saturated units and hydroxyl groups. The maximum room temperature conductivity of the film was 10-1 S cm-1. The conductivity of the film in the temperature range from -150°C to 30°C obeyed the relation of ln
σ∞T-0.25. The thermopower of the film was positive. These electrical properties are similar to those of electrochemically prepared polypyrrole.
Improved Tellurium Films by Partially Ionized Vapor Deposition as the Semiconductor Layer of a TFT and a Hydrogen Sensor
Authors: Okuyama Katsuro , Kudo Hideko
Published: February 2005

Semiconducting properties of tellurium films prepared on glass substrate by a partially ionized vapor deposition (PIVD) technique were studied and compared with those of Te films formed by a conventional vacuum evaporation technique. It was found that the PIVD technique effectively increased the Hall mobility and decreased the carrier concentration of Te films. These improved films could be utilized as the semiconductor layer of a thin film transistor(TFT) with smaller pinch-off voltage. A Te TFT with 10 nm-thick paladium film as the gate electrode was fabricated and its sensitivity to hydrogen gas was examined.
High-Power AlGaAs/GaAs DH Stripe Laser Diodes on GaAs-on-Si Prepared by Migration-Enhanced Molecular Beam Epitaxy
Authors: Kim Jae-Hoon , Radhakrishnan Gouri , Nouhi Akbar , Liu John K. , Lang Robert J. , Katz Joseph
Published: February 2005

We report on high-power low-threshold AlGaAs/GaAs double heterostructure (DH) stripe laser diodes on Si substrates by a hybrid growth of migration-enhanced molecular beam epitaxy (MEMBE) and metalorganic chemical vapor deposition (MOCVD). MEMBE-grown GaAs-on-Si had excellent surface morphology and showed much lower dislocation density than that of normal two-step MBE-grown or in situ annealed layers. The MEMBE growth and material characterization are described in detail. The 6-µm-wide oxide stripe lasers showed the highest peak power of up to 184 mW per facet reported to date, room-temperature pulsed threshold currents as low as 150 mA, and differential quantum efficiencies as high as 30% without mirror facet coating. The intrinsic threshold current density has been estimated to be about 2 kA/cm2 when taking current spreading and lateral diffusion effects into account. For comparison, the room-temperature pulsed threshold current density of 1.1 kA/cm2 was obtained for the broad-area DH laser diode fabricated on GaAs substrates in the same epitaxial deposition.
Kinetic Analysis of Pressure-Induced Phase Transition by Means of Raman Scattering
Authors: Takano Kaoru J. , Tabata Ken-ichi , Wakatsuki Masao
Published: February 2005

A new method has been devised to observe the kinetic process of pressure-induced phase transitions proceeding rather rapidly. The transition is induced by a pressure jump in a diamond anvil cell. Raman scattering spectra of the sample are measured repeatedly during the transition. The volume fraction of a phase, with its time dependence, is evaluated from the integrated intensities of a Raman peak attributed to the phase, on an assumption of a proportional relation between the peak intensity and the volume of the corresponding phase. From a theoretical viewpoint the proportional relation is expected to hold in some cases that seem to be practical. Experimental examination for the red-to-yellow phase transition in HgI2 shows a strong support of the proportional relation, and reveals the usefulness of the new method.
Sn–Te–Se Films for Reversible Phase-Change Optical Recording
Authors: Terao Motoyasu , Nishida Tetsuya , Miyauchi Yasushi , Kaku Toshimitsu , Horigome Shinkichi , Sugita Yutaka
Published: February 2005

Characteristics of optical recording films that consist of Sn–Te–Se and have an amorphous crystalline phase change recording mechanism are analyzed. High crystallization temperatures and high crystallization activation energies, which certify the long life of the recorded dots, can be obtained for compositions whose ratio of Sn concentration to Se concentration is about 1 to 2. Among these compositions, high speed erasing, long life of the recorded dots, and high recording sensitivity are achieved in compositions whose Te concentration is 10 to 20 at%. When the Te concentration is 50 to 60 at% and the Se concentration is 17 to 25 at%, the crystallization temperature of the recorded dots is much lower than that of the as-deposited amorphous state.
DC Bias Effects on Growth of a-Ge:H in Coaxial-Type ECR Plasma
Authors: Aoki Takeshi , Kato Seiichi , Hirose Masataka , Nishikawa Yasuo
Published: February 2005

Deposition conditions for obtaining high-quality a-Ge:H are investigated by means of a coaxial-type ECR plasma CVD reactor in which a substrate is placed along a magnetic field. The application of a negative bias to the substrate is found to be crucial to elimination of the postoxidation of deposited films, densification of the matrix, and improvement of the photoelectronic properties. This paper particularly focuses on the substrate bias effects on the structural and compositional inhomogeneities, film stress, chemical resistance and photoelectronic properties of a-Ge:H. The results are explained in terms of moderate ion bombardment caused by the substrate bias ranging from -50 V to -100 V.
High-Resolution Reflection Electron Microscopy of Si(111)7×7 Surfaces Using a High-Voltage Electron Microscope
Authors: Koike Hideki , Kobayashi Kunio , Ozawa Soh-ichiro , Yagi Katsumichi
Published: February 2005

High-resolution reflection electron microscope (REM) observations of Si(111)7×7 surfaces have been carried out by means of an ultra-high-vacuum 1 MV microscope. An advantage to the use the high-resolution 1 MV microscope is the reduction of resolution degradation due to chromatic aberration. When the observations are carried out along the [11̄0] direction, 2.3 nm lattice fringes of the 7×7 unit cell size are observed. When several beams are included in the objective aperture, finer fringes, i.e., three fringes and seven fringes in 2.3 nm, are observed. The fact that the former fine fringes are frequently observed instead of half-spacing fringes of the 2.3 nm fringes seems to suggest that the fringes reflect the 7×7 reconstructed structure. The latter fine fringes are the narrowest fringes with spacing of 0.33 nm so far recorded in REM. When Au is deposited to form the 5×2 adsorbate structure, fringes of the half spacing of the 5 period are recorded. This may reflect the adsorbate structure, a conclusive model of which has not been reported.
Transmission Electron Microscopic Study of Electroless Nickel-Molybdenum-Boron Alloy Films
Authors: Osaka Tetsuya , Arai Katsuya , Masubuchi Naganori , Yamazaki Yohtaro , Namikawa Tatsuru
Published: February 2005

The structure of amorphous and crystalline electroless Ni–Mo–B films was studied by transmission electron microscopy (TEM). The amorphous film in as-deposited conditions was of a completely disordered state with few crystalline regions. This film crystallized by means of nucleation after 300°C annealing; the produced nuclei grew large after 500°C annealing. Two crystalline films in the as-deposited state, plated from 0.005 and 0.010 mol dm-3 Na2MoO4 concentration baths, showed different annealing behavior even though they had almost identical Ni and Mo composition. The former contained amorphous-like regions corresponding to an intermediate state between the amorphous and the crystalline. The latter film was so stable against annealing that the structure of small grains was maintained after 500°C annealing.
Radiation Induced Si–SiO2 Interface States and Positive Charge Buildup of MOS Capacitors Annealed in Nitrogen and in Hydrogen After Metalization
Authors: Ohnishi Kazunori , Ushirokawa Akio
Published: February 2005

The density of Si–SiO2 interface states (Δ
D
it) and the density of trapped oxide charges (Δ
N
ot) generated by Co-60 gamma ray irradiation are examined for MOS capacitors with post metalization annealing (PMA) in hydrogen and in nitrogen. A good correlation between |Δ
V
mg-Δ
V
FB| and \int D
it dE is found, and it verifies that the charging at the interface states affects the estimation of Δ
N
ot from the V
FB shift. The radiation hardness of the MOS structure is sensitive to annealing conditions. PMA is effective in decreasing Δ
D
it and Δ
N
ot. The PMA effect is discussed in terms of weak bond and interstitial hydrogen atoms. Moreover annealing after irradiation is found to be effective in recovery of radiation damage on MOS devices.
Electron Energy Loss Spectrum in Adsorbed Residual Gas on Cooled Arachidic Acid Langmuir-Blodgett Film and Its Adsorbed Gas Amount
Authors: Kawakami Hirokane , Nisimura Keigo , Ohshima Takayoshi , Shibata Seiichi , Shoji Yoshihiko , Sugai Isao , Ukai Kumataro , Yasuda Takahiro , Morikawa Naotake , Nogawa Norio , Nagafuchi Teruyasu , Naito Fujio , Suzuki Takeshi , Taketani Hiroshi , Iwahashi Makio , Hisatake Kazuo , Fujioka Manabu , Fukushima Yasutaka , Matsuda Takeshi , Taniguchi Takashi
Published: February 2005

The energy-loss spectra of 18 keV electrons in adsorbed residual gas on Langmuir-Blodgett film, made from arachidic acid (C20H40O2) and cooled at temperatures of -10°C, -35°C and -60°C, were measured through use of an electron source that also acted as an adsorbent. In addition, the amount of adsorbed residual gas was estimated from the energy-loss probability.
Fundamental Characteristics of AC Flashover on Contaminated Insulators Covered with Ice
Authors: Sato Masashi , Saito Hiroshi , Kaga Akio , Akagami Hideo
Published: February 2005

The fundamental characteristics of ac contaminated flashover on iced insulators were studied for the three icing states, i.e., glaze, hard rime and soft rime, which are observed most frequently in service conditions. The results showed that thawed snow with a relatively low salt concentration can produce a salt deposit density (SDD) high enough for flashover on an iced insulator. For the same concentration of contamination liquid, average values of SDD for icing states are 5 to 9 times higher than those for icing-free conditions. The results also showed that the minimum flashover stress of the soft rime condition is 20% lower than that of icing-free conditions. For this reason, we deduced that the number density of Na atoms in the discharge space at flashover tends to become highest under the soft rime conditions.
Thermostat for Dynamic Light Scattering Measurements at High Temperatures
Authors: Gemma Tohru , Ogino Kazuyoshi
Published: February 2005

A simple thermostat of the double-chamber type used to measure dynamic light scattering at temperatures up to 160°C has been developed. A temperature stability of 0.01°C has been accomplished at 160°C. A new refractometer for high-temperature measurements is also described.
Use of Magnetic Semiconductor Ceramic Modules for a Multisensor and Protective Relay
Authors: Seki Kyoshiro , Chiba Shigeki , Higaki Tetsuro , Shida Jun-ichi , Murakami Koichi
Published: February 2005

The versatile module system using magnetic semiconductor ceramic (MSC), which represents one kind of ferrite, has been developed for use in measurements and as a safe guard. The magnetic and electrical properties in the MSC have temperature, humidity and gas concentration dependence and a switching function. The use of MSC provides the same function as adding a ferrimagnetic substance, a thermistor, a capacitor and/or a switching element to the system. Considering these characteristics, the MSC system for temperature/humidity/gas sensors and overvoltage relay can be realized. The system is used in the field of environmental management and as a safety monitor.
Calibration of the Detection Angle in the Magnetic Spectrometer System
Authors: Yasue Masaharu , Fuchi Yoshihide
Published: February 2005

A simple method is described to calibrate the detection angle in the measurement of nuclear reactions using kinematics for the known states in residual nuclei. The angle calibration ensures the use of contaminated peaks in the energy spectrum as energy scale markers.
The Axial Electric Field of a Positive Column in a Capillary Discharge Tube
Authors: Kaneda Teruo , Kubota Tadahiro , Chang Jen-Shih
Published: February 2005

The axial electric field of a positive column in capillary discharge tubes was measured for helium, neon, argon, krypton and xenon. The tubes used had diameters of 0.8 and 0.5 mm, the gas pressure was varied from 0.8 to 40 Torr and the discharge current was varied from 10 to 30 mA.
A Switching Device of a PN Junction Structure with Two Layers of Thin Oxide
Authors: Chang David C. Y. , Lee Chung Len , Lei Tan Fu
Published: February 2005

A switching device has been made using two layers of thin oxide. Two conjugate face-to-face MIS's are used to replace the PN+ (or NP+) junctions. The electric I-V characteristics of this MINPIM device measured in experiments are presented in this paper. The experiments show that over-voltage stress may cause the NP junction to avalanche and lead to switching. One or two switchings will occur depending on the oxide layers. The holding voltage is also related to the base width. Proper base biasing may enhance the energy band shift or the minority carrier injection ratio and reduce the breakover voltage or holding voltage, respectively.
Magnetic Properties of Rapidly Quenched Ternary Oxides Li2O–Bi2O3–Fe2O3System
Authors: Nakamura Shinichi , Ichinose Noboru
Published: February 2005

Ternary oxides in the system Li2O–Bi2O3–Fe2O3were prepared by rapid quenching from the melt by means of a twin-roller apparatus. As-quenched samples turned out to be X-ray amorphous, and ferromagnetic behaviour was observed at room temperature. Particularly, the amorphous (Li2O)25(Bi2O3)25(Fe2O3)50specimen has magnetization value of about 4.5 emu/g (15 kOe) at room temperature. This specimen shows an irreversible thermomagnetization process below about 200 K in a weak magnetic field, indicating the existence of magnetic frustration. The57Fe Mössbauer absorption spectra indicate that this specimen is composed of two different phases, short-range antiferromagnetic and ferromagnetic, and that the latter is less disordered (or crystallinelike). The magnetic frustration seems to be caused by the competition between exchange interactions at the interface of these phases.
Photocurrent of Solution-Grown Thin Polycarbonate Films Containing Soluble Nickel-Phthalocyanine
Authors: Nakamura Shuhei , Ozaki Tamon , Toriyama Kazuyuki , Iida Kazuo , Sawa Goro
Published: February 2005

The photocurrent of solution-grown polycarbonate film containing 25 phr soluble NiPcX4 was measured. The photocurrent showed an antibatic relationship with the wavelength of irradiated light. When the photocurrent was measured only in the irradiated region, it showed a symbatic relationship. The reasons for these findings were discussed via a model which took into account both the kinetics of photogenerated carriers in the irradiated region and the field-dependent carrier mobility. Appearance of the antibatic photocurrent was found to be caused by high resistivity in the non irradiated region of the sample.
Stimulated Emission due to Electromagnetic Breakthrough in InSb at Room Temperature
Authors: Morimoto Takeshi , Chiba Meiro
Published: February 2005

Spectral narrowing of the infrared emission due to band-to-band recombination in bulk InSb has first been observed at room temperature when high currents have been passed across the applied high magnetic field. This is clear evidence supporting stimulated emission due to an inverted population caused by the interband breakthrough of electrons by strong action of the resulting electromagnetic force. Outstanding nonlinear relationships have also been observed in the voltage-current characteristics under high magnetic fields thus suggesting the electromagnetic breakthrough.
Very Low Threshold AlGaAs/GaAs Quantum Well Lasers Fabricated by Self-Aligned Impurity Induced Disordering
Authors: Sugimoto Mitsunori , Hamano Noboru , Takado Norikazu , Asakawa Kiyoshi , Yuasa Tonao
Published: February 2005

Threshold current as low as 1.2 mA has been achieved in GaAs/AlGaAs quantum well (QW) laser diodes. The low threshold current reflects the high quality of the QW crystal and the low level of leakage current attained in the buried heterostructure. This heterostructure was fabricated with a novel self-aligned mesa etching and Si diffusion process on a molecular beam epitaxy grown planer QW structure. Both the low threshold current and the precisely controllable fabrication process make these lasers quite suitable for optoelectronic integration.
Anisotropic Characteristics of Drawn Poly(3-alkylthiophene) Gel
Authors: Yoshino Katsumi , Nakao Kenji , Onoda Mitsuyoshi
Published: February 2005

Highly drawn poly(3-alkylthiophene) gels have been prepared by either drawing poly(3-alkylthiophene) gels or irradiating highly drawn soluble poly(3-alkylthiophene) with γ-rays. Both types of gels demonstrated reversible changes in length in the direction perpendicular to the drawing direction upon change in temperature, solvent composition and also doping. However, the change in length parallel to the drawing was negligible.
X-Ray Diffraction Analysis of One-Dimensional Quasiperiodic Superlattices Grown by Migration-Enhanced Epitaxy
Authors: Yymaguchi Hiroshi , Horikoshi Yoshiji
Published: February 2005

Two different structures of one-dimensional quasiperiodic AlAs/GaAs superlattice are fabricated by migration-enhanced epitaxy, and their structural properties are studied by X-ray diffraction. One structure is a well-known Fibonacci superlattice. The influence of interface roughness on the satellite peaks is analyzed for structures with a unit layer thickness of only three monolayers. The full width at half maximum of these peaks shows that the interface roughness in the structures grown by MEE is about half that of structures grown by MBE. The other structure is a Harper superlattice. In this structure, the mole fraction x of each Al
x
Ga1-x
As unit layer is modulated according to a cosine function. The experimental results show the advantage of MEE for growing such composition-modulated structures.
Preferential Diffusion of Vacancies Perpendicular to the Dimers on Si(001)2×1 Surfaces Studied by UHV REM
Authors: Kahata Hisatoshi , Yagi Katsumichi
Published: February 2005

This paper describes anisotropic diffusion of vacancies on Si(001)2×1 surfaces studied by reflection electron microscopy. Vacancies were introduced uniformly on surface terraces of rectangular 2×1 and 1×2 domains of similar size by exposure to oxygen at 10-8Torr at 700°C. The longer sides of the 2×1 and 1×2 domains were perpendicular and parallel to the dimer direction, respectively. It was observed that hollows were nucleated by coalescence of the vacancies preferably in the 2×1 domains. This was due to anisotropy of vacancy diffusion which caused different vacancy concentrations in the two domains. This fact indicates that easy diffusion of the vacancies is perpendicular to the dimer direction.
Surface Structure Analysis of Polycrystalline Zinc by SEELFS and EAPFS
Authors: Konishi Ryōsuke , Arioka Masato , Sasakura Hiroshi
Published: February 2005

From the view point of comparing SEELFS with EAPFS, we tried to measure the fine structure above the Zn-M2,3 threshold of polycrystalline zinc. From the result of SEELFS, we were able to obtain a nearest-neighbour atomic spacing of 0.242 nm. In EAPFS, we obtained the nearest-neighbour atomic spacings of 0.241 (l=2), 0.251 (l=1) and 0.261 nm (l=0). The result of EAPFS agrees well with that of SEELFS when we assume a final state of l=2, in spite of a lack of dipole selection rules.
S(KLL) Anger Resonancelike Phenomena for Solid Samples
Authors: Matsubayashi Nobuyuki , Shimada Hiromichi , Kojima Isao , Kurahashi Masayasu , Ohta Toshiaki , Itoh Akio , Nishijima Akio
Published: February 2005

S(KLL) Auger spectra of several solid samples were measured using synchrotron radiation as an excitation source. For the samples containing S6+, the intensities and peak position of the spectrum were changed on changing the incident X-ray energy near the S K-edge absorption. This behavior was ascribed to a resonance phenomenon of Auger electrons which was recently reported for gaseous molecules.
The Preparation and Characterization of Diamond Powder by DC Arc Plasma
Authors: Chonan Takeshi , Uenura Mikio , Futaki Shoji , Nishi Shigekazu
Published: February 2005

Diamond powder was synthesized by the plasma CVD method for the first time in the world. Acetylene (C2H2) and hydrogen (H2) gases were used for starting materials. The arc plasma with these gases was led onto the quenching disk and the plasma was rapidly quenched. A gray powder was deposited on the inner wall around the quenching disk. The powder consisted of spherical particles and was confirmed to be a cubic diamond with a little amorphous carbon according to Raman spectra and X-ray diffraction.
The Staebler-Wronski Effect on Defect Luminescence in Hydrogenated Amorphous Silicon
Authors: Tajima Michio , Ohyama Hideaki , Okushi Hideyo , Yamasaki Satoshi , Tanaka Kazunobu
Published: February 2005

Defect luminescence in hydrogenated amorphous silicon has been selectively excited by below band-gap excitation at 4.2 K. The Staebler-Wronski (SW) effect has been investigated by comparing defect luminescence before and after prolonged light soaking of the samples. Two types of luminescence change have been observed: the 0.83 eV band in an undoped sample gains intensity after the light-soaking process, while the 0.85 eV band in a P-doped sample loses intensity. This result is compared with the SW effect reported for dangling-bond states. The present result is evidence for the theory that there are two kinds of defect states associated with dangling bonds.