bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Artificially Layered Bi-Sr-Ca-Cu Oxide Films and Their Thermal Stability
Authors: Nakamura Keikichi , Sato Junichi , Kaise Masatsugu , Ogawa Keiichi
Published: February 2005

Bi-O/Sr-Ca-Cu-O multilayered films have been synthesized using two target reactive magnetron sputtering. It is shown that the modulation wavelength \varLambda (c/2 for the crystals) can be simply controlled by varying the deposition time for a one layer unit of Sr-Ca-Cu-O while keeping that for Bi-O constant. The films thus obtained have smooth surfaces and have \varLambda's ranging from 12 to 26 Å, i.e., almost equal to those of the crystalline or intergrowth phases o bserved in the Bi-Sr-Ca-Cu-O system. The thermal stability of these artificially layered films is also reported.
The Formation of the High-Tc Phase in Pb-Doped Bi-Sr-Ca-Cu-O System
Authors: Kim C. J. , Rhee C. K. , Lee H. G. , Lee C. T. , Kang S. J-L. , Won D. Y.
Published: February 2005

The microstructure on the formation of the high-T
c phase was investigated in the Pb-doped Bi-Sr-Ca-Cu-O system. The high-T
c phase was well stabilized for the composition of 1.4:0.6:2:2:3.6 for Bi:Pb:Sr:Ca:Cu. The fraction of the phase depends on the reaction time. At the early and intermediate stages of reaction, several phases such as Sr3-x
Ca
x
Cu5O
y
, (Pb, Ca)-rich phase, the low-T
c phase and high-T
c phase were observed. At these stages, the low-T
c phase was dominant. The low-T
c phase was transformed into the high-T
c phase through prolonged heat treatment, but a small amount of the low-T
c phase and Sr3-x
Ca
x
Cu5O
y
remained. The cation ratio in the high-T
c phase was approximately 4:8:5:10 for (Bi, Pb):Sr:Ca:Cu.
Monolithic Eight-Channel High-Power Low-Astigmatism AlGaAs Laser Diode Array
Authors: Tsunekane Masaki , Endo Kenji , Ishikawa Shin , Katayama Ryuichi , Yoshihara Kazuhiro , Kubota Keiichi , Yuasa Tonao
Published: February 2005

A monolithic eight-channel individually addressable AlGaAs laser diode array, usable in parallel data transfer optical disk memory systems, has been developed. 40 mW cw output power in the fundamental transverse mode with beam astigmatism less than 2 µm has been obtained for each of eight channels. Operating characteristics are highly uniform across the array and thermal crosstalk is of little significance. We successfully demonstrated the first four-channel parallel read operations of an optical disk using the laser diode array as a light source.
AES Observation on the Photochemically Washed Surface of GaAs
Authors: Oigawa Haruhiro , Fan Jia-Fa , Nannichi Yasuo
Published: February 2005

A GaAs surface prepared by photochemical washing (PCW) has been studied by means of AES. We found that improvement and degradation in the PL intensity on the treated surface were related to the removal and reaccumulation respectively, of excess As in the surface oxide. The effect for passivation of the GaAs surface by PCW is found to be temporary and unreliable.
Electroluminescence from a ZnSe p-n Junction Fabricated by Nitrogen-Ion Implantation
Authors: Akimoto Katsuhiro , Miyajima Takao , Mori Yoshifumi
Published: February 2005

Electroluminescence has been obtained from ZnSe p-n junctions. ZnSe films were grown on n-type GaAs substrates by molecular beam epitaxy. The dopant used for n-type ZnSe was Ga, and p-type ZnSe was formed by nitrogen ion implantation into undoped ZnSe which was grown on the Ga-doped ZnSe layer. Rapid thermal annealing was performed using an infrared lamp in N2 ambient. The formation of a p-n junction was confirmed by measuring electron beam-induced current. The electroluminescence spectra were dominated by two peaks of band-edge emission at 446 and 459 nm at 77 K.
Formation and Degradation of the 120 K Tc Phase in the Tl-Pb-Sr-Ca-Cu-O System
Authors: Itoh Takao , Uchikawa Hiroshi
Published: February 2005

Time-dependent formation and degradation processes of the 120 K T
c phase in the Tl-Pb-Sr-Ca-Cu-O system have been investigated by measuring the temperature-dependent resistivity, and by X-ray diffraction, fluorescent X-ray and EPMA analyses. It is shown that the 80 K T
c phase ((Tl, Pb)(Sr, Ca)3Cu2O
x
) changes partly to the 120 K T
c phase ((Tl, Pb)(Sr, Ca)4Cu3O
x
) upon prolonged heat treatment, and that the resultant 120 K T
c phase changes again to the 80 K T
c phase upon heat treatment in the presence of an excess amount of Tl2O3.
Preparation of High Jc Bi-Sr-Ca-Cu-O Bulk Sample by Floating Zone Method
Authors: Kubo Yukio , Michishita Kazuo , Higashida Yutaka , Mizuno Masatoshi , Yokoyama Hisanori , Shimizu Noriyuki , Inukai Eikichi , Kuroda Noboru , Yoshida Hiroshi
Published: February 2005

Bi-Sr-Ca-Cu-O bulk samples with three different nominal compositions of Bi2Sr2CaCu2O
y
, Bi2Sr2Ca2Cu3O
y
and Bi0.7Pb0.3SrCaCu1.8O
y
were prepared by the floating zone method at growth rates ranging from 2 mm/h to 70 mm/h. The sample grown at 2 mm/h with the nominal composition of Bi2Sr2CaCu2O
y
possessed high density, highly aligned morphology, and a transport critical current density higher than 1490 A/cm2 at 77 K under a zero magnetic field without any postannealing.
Preparation of Superconductive (Bi, Pb)-Sr-Ca-Cu-O Thick Films by Rapid Quenching
Authors: Shimomura Shuichi , Takahashi Koichiro , Seki Hiroyuki , Sakata Koichiro , Takenaka Tadashi
Published: February 2005

High-T
c superconductive thick films in the (Bi, Pb)-Sr-Ca-Cu-O system were prepared by rapid quenching. The asquenched film was amorphouslike and after annealing at 840°C, it showed superconductivity. The high-T
c phase of the film increased with the increase of the annealing time. The thick films annealed at 840°C for 300 h showed superconductivity with T
c(zero)=104 K and J
c=200 A/cm2 at 77 K.
Thin Film Growth of YBa2Cu3O7-x by ECR Oxygen Plasma Assisted Reactive Evaporation
Authors: Aida Toshiyuki , Tsukamoto Akira , Imagawa Kazushige , Fukazawa Tokuumi , Saito Sakae , Shindo Keijiro , Takagi Kazumasa , Miyauchi Katsuki
Published: February 2005

A new apparatus equipped with an ECR oxygen plasma source, a co-evaporation system of Y, Ba and Cu and a differential pumping system was developed. YBa2Cu3O7-x
superconducting films were obtained at a substrate temperature of 450–500°C. The critical temperatures of films deposited on SrTiO3, MgO and Si substrates were 87 K, 80 K and 63 K, respectively. These properties were closely related to the crystallinity of the film.
Effects of Oxygen Partial Pressure and Substrate Temperature on Crystalline Orientation in Y-Ba-Cu-O Films Prepared by Sputtering
Authors: Terashima Yoshiaki , Sagoi Masayuki , Kubo Kohichi , Mizutani Yoshihisa , Miura Tadao , Yoshida Jiro , Mizushima Kohichi
Published: February 2005

The dependence of crystalline orientation in Y-Ba-Cu-O films on oxygen partial pressure and substrate temperature has been investigated for films prepared by magnetron sputtering on (100) SrTiO3 and (100) MgO substrates. The tendencies for preferential orientation were the same on both substrates. At low oxygen pressures, the c-axis was oriented perpendicularly to the film plane. In contrast, a/c-axis oriented films were formed at intermediate oxygen pressures, and the a-axis was oriented at high oxygen pressures. At higher temperatures, c-axis oriented films were formed, even at high oxygen pressures.
High Quantum Efficiency, High Output Power 1.3 µm GaInAsP Buried Graded-Index Separate-Confinement-Heterostructure Multiple Quantum Well (GRIN-SCH-MQW) Laser Diodes
Authors: Kasukawa Akihiko , Murgatroyd Ian John , Imajo Yoshihiro , Matsumoto Narihito , Fukushima Toru , Okamoto Hiroshi , Kashiwa Susumu
Published: February 2005

We have fabricated a high quantum efficiency (40%/facet), low internal loss (5 cm-1), high output power (62 mW/facet) 1.3 µm GaInAsP buried graded-index separate-confinement-heterostructure multiple quantum well (GRIN-SCH-MQW) laser diode entirely grown by metalorganic chemical vapor deposition (MOCVD). This laser diode operated in a single longitudinal mode in a relatively wide temperature range of 35°C without any mode hopping. The minimum spectral linewidth of 2.3 MHz was realized at an output power of 7 mW for a laser diode with cavity length of 900 µm. The beam divergence angle is considerably smaller than that of the conventional DH laser diodes.
A Four-Band Hubbard Model for Doped CuO5 and Related Clusters. Populations of Holes on Apex Oxygens Determined by the Full VB CI Method
Authors: Yamaguchi Kizashi , Namimoto Hideo , Nakano Masayoshi , Fueno Takayuki
Published: February 2005

Four-band Hubbard Hamiltonians for CuO5 and related clusters were exactly diagonalized by the valence-bond (VB) full configuration interaction (CI) technique. It was found that O2p holes are mainly introduced into the p

x
y
=orbitals of the CuO2 plane, while they can be distributed over the 2p
z-orbitals of apex oxygens under the specific condition that the orbital energy gap between apex and plane oxygens exceeds a certain threshold (1.5 eV). Implications of these results are discussed in relation to high-T
c superconductivity for copper oxides.
Effect of Structure on Transport Characteristics of Ballistic One-Dimensional Channel
Authors: Hirayama Yoshiro , Saku Tadashi , Horikoshi Yoshiji
Published: February 2005

Ballistic one-dimensional (1-D) channels are fabricated by focused Ga ion beam scanning on two different modulation-doped wafers. Higher electron density causes a smaller transition region length between the 1-d channel and two-dimensional (2-D) ohmic regions. A ballistic 1-D channel with a smaller transition region shows conductance oscillation in addition to quantized step structures. This oscillation is explained by the interference of electron waves reflected at both ends of the 1-D channel. On the other hand, a ballistic channel with a larger transition region shows quantized step structures without conductance oscillation.
Photoluminescence of a Novel Hetero n-i-p-i Structure Incorporating Triple Quantum Wells
Authors: Tokuda Yasunori , Kanamoto Kyozo , Tsukada Noriaki
Published: February 2005

We have examined fundamental properties of a new type of n-i-p-i structure, where coupled GaAs triple quantum wells are sandwiched between the alternately n- and p-doped AlGaAs regions, by means of photoluminescence measurements. The unique results are explained in terms of an anticrossing of the quantized levels as well as distributions of electrons and holes.
Properties of High Heat-Resistance µc-SiCx:H Emitter Silicon HBT's
Authors: Kuwagaki Mamoru , Imai Kazuo , Amemiya Yoshihito
Published: February 2005

Properties of µc-SiC
x
:H prepared by plasma CVD are studied with emphasis on microcrystallite growth and thermal stability. A small percentage of carbon added to µc-Si:H effectively suppresses crystalline-grain growth which degrades the wide-bandgap effect. As a result, the µc-SiC
x
:H-emitter HBT yields higher current gains than the µc-Si:H-emitter HBT over the entire current range measured. Greater heat-resistance properties are also observed. Accordingly, a current gain as high as 450 is maintained even after 450°C annealing.
Superconductivity in a Tl-Pb-Pr-Sr-Cu-O System
Authors: Adachi Seiji , Inoue Osamu , Hirano Hirohumi , Takahashi Yukihiro , Kawashima Syunichiro
Published: February 2005

Superconductivity in the Tl-Pb-Ln-Sr-Cu-O (Ln=La, Pr, Nd) system has been found. Samples were synthesized by annealing of precursors, Pb-Ln-Sr-Cu-O ceramics, in Tl oxide vapor. In the case of Ln=Pr, electrical resistance vanished below 43 K, and the Meissner effect appeared below 46 K.
Crystal Structure of the High-Tc Phase in the Pb-Bi-Sr-Ca-Cu-O System
Authors: Kijima Naoto , Endo Hozumi , Tsuchiya Jun , Sumiyama Akihiko , Mizuno Masaaki , Oguri Yasuo
Published: February 2005

The crystal structure of the high-T
c phase (T
c∼107 K) in the Pb-Bi-Sr-Ca-Cu-O system has been analysed by the Rietveld method on the basis of the X-ray powder diffraction data. The crystal structure belongs to the space group Bbmb and its lattice parameters are a=5.407(6) Å, b=5.407(6) Å and c=37.051(7) Å. The crystal structure is quite similar to that of the high-T
c phase (T
c∼125 K) of Tl2Ba2Ca2Cu3O10. A flat Cu-O plane and two zigzag Cu-O planes are sandwiched between two Bi-O planes in the crystal structure. It was found that Pb atoms occupy the Bi, Sr and Ca sites by 9%, 7% and 3%, respectively.
REM Observation on Conversion between Single-Domain Surfaces of Si(001) 2×1 and 1×2 Induced by Specimen Heating Current
Authors: Kahata Hisatoshi , Yagi Katsumichi
Published: February 2005

A current-induced conversion between Si(001)2×1 and 1×2 surfaces is observed in situ by ultrahigh-vacuum reflection electron microscopy. When the specimen is annealed with a certain current above 700°C, the surface is composed of two domains divided by single-height steps, but one type of domain is much wider than the other. When the current direction is reversed, narrow terraces widen their areas as a result of movements of higher side steps to the higher side and slight movements of lower side steps to the lower side. The wider terraces reduce their width. The process is quicker at higher temperature. It was found that the type of major domain is determined on the basis of whether the current is in the step-up or the step-down direction.
Work Function Measurements of (W-Sc2W3O12)-Coated Impregnated Cathode by Retarding Potential Method Utilizing Titaniated W(100) Field Emitter
Authors: Yamamoto Shigehiko , Yaguchi Tomio , Sasaki Susumu , Watanabe Isato
Published: February 2005

The work function of a (W-Sc2W3O12)-coated impregnated cathode, known as a high current density cathode operable at low temperature, is measured for the first time by the retarding potential method utilizing a titaniated W(100) field emitter as an electron source of high current stability and high brightness. A gradual change in the work function of the cathode is depicted during the activation procedure. Activation is completed after 2 h heating at 1150°Cb, when the work function becomes 1.15 (-0.02, +0.112) eV.
A New Method to Find Plasma Position in Tokamak
Authors: Rai V. N. , Mattoo S. K.
Published: February 2005

In this paper we propose a novel method for measurement of plasma position in tokamak. This involves measurement of horizontal flux using two radial loops subtending different solid angels on vessel centre and difference of poloidal flux at the top and bottom side of the plasma column. This method does not require the knowledge of equilibrium vertical field.
Preparation of Superconducting YBa2Cu3O7-x Films by ECR Plasma Sputtering
Authors: Goto Takashi , Masumoto Hiroshi , Hirai Toshio
Published: February 2005

Y-Ba-Cu-O films were prepared on (100)MgO single crystal substrates by ECR plasma sputtering. As-deposited films without substrate heating were amorphous and electrically insulating. The amorphous film was crystallized to YBa2Cu3O7-x
by postannealing at 930°C for 1 min in O2 gas, and the T
c of the postannealed film was 70.5 K. The film prepared at the substrate temperature of 650°C was crystalline YBa2Cu3O7-x
and the T
c of the film without any postannealing was 73 K.
Investigation of Cu Valence by Means of EPMA
Authors: Koyama Kuniyuki , Suzuki Yasuji , Matsuo Eiji , Itoh Yoshinori , Noguchi Seiichiro
Published: February 2005

The valence of Cu ions in various Cu-compounds is estimated by means of the energy-dispersive EPMA method. The Intensity ratio of a characteristic line Lα to Kβ, Lα/Kβ, decreases exponentially with increasing Cu valence as examined for standard samples: metallic Cu (Cu0+), Cu2O (Cu1+), CuO (Cu2+) and NaCuO2 (Cu3+). The relation between Lα/Kβ and Cu valence appears as different functions for different accelerating voltages, but is reduced to a universal function after ZAF correction and normalization. In addition to the standard samples, CuF2 (Cu2+) is measured to investigate the same function. This method can be used for estimation of Cu valence in high-T
c oxide superconductors, if a quantitatively good correction is performed.
Sintering of Powdered Matter by Ablation Pressure due to Irradiation of Focused Pulse Intense Ion Beam
Authors: Matsukawa Yoshinobu , Uegami Kenjiro
Published: February 2005

A small amount of powder was sintered by the ablation pressure of 20∼30 kilobars generated by the irradiation of a focused ion beam with a high power density of 1.1×1010 W/cm2. By the observation of a sintered mixture of two metals (aluminium and tin), it was known that powder grains did not melt but that the two metals merge in a thin layer of ∼0.8 µm in thickness on the surface of the grains and that metal in a flowing or melted diffusible state under high pressure infiltrated the gaps between the powder grain boundaries.
The Local-Environment-Dependent DX Centers: Evidence for the Single Energy Level with a Specified Configuration
Authors: Baba Toshio , Mizuta Masashi , Fujisawa Toshimasa , Yoshino Junji , Kukimoto Hiroshi
Published: February 2005

The energy-level structure of the D
X centers corresponding to specific local environments was investigated under hydrostatic pressure. Several discrete D
X levels, each of which was a well-defined single level, were clearly resolved. The energy level of the Si D
X center surrounded only with Ga was determined to be 295 meV above the Γ-conduction band edge of GaAs. When Al is coordinated as the 2nd-nearest neighbor, the energy level is lowered by as much as 120 meV. The energy level is sensitive not only to the number of Al 2nd-nearest neighbors, but also to the atomic configuration itself.
XPS Studies of Bi-Sr-Ca-Cu-O Single Crystal and Ceramics Surfaces
Authors: Kishida Satoru , Tokutaka Heizo , Nakanishi Shuuichi , Watanabe Yoshihide , Fujimoto Hiroshi , Nishimori Katsumi , Ishihara Naganori , Futo Wataru , Torigoe Seiji , Harada Hisamochi
Published: February 2005

The XPS (X-ray photoelectron spectroscopy) spectra from (a) the cleaved surface of a single crystal, (b) the polished surface and (c) the Ar+-sputtered surface of the ceramics in Bi-Sr-Ca-Cu-O are mecnsured and compared. The chemical bond nature of Bi is the same in all three surfaces. Sr and Ca in (c) are more oxidized than those in (a). In (b), there are two kinds of Sr and Ca, one from a clean surface like the cleaved surface region, and the other, more oxidized Sr and Ca which exist in the Ar+-sputtered surface. Cu2+ is dominant in (a) and (b), while Cu+ is dominant in (c). The O 1s XPS spectrum from (c) is sharper and narrower than that from (a). This may be due to the existence of isolated metal oxides of Sr, Ca and Cu by Ar+-sputter etching.
Growth of the 2223 Phase in Bi-Sr-Ca-Cu Oxide Films under a Controlled Pb Potential
Authors: Hayakawa Hirotoshi , Kaise Masatsugu , Nakamura Keikichi , Ogawa Keiichi
Published: February 2005

Growth of the 2223 phase in Bi-Sr-Ca-Cu oxide films has been found to increase significantly by annealing the Pb-free, sputter-deposited amorphous film with a Pb source pellet, i.e., Bi-Pb-Sr-Ca-Cu oxide, in a closed Au capsule kept at temperature around 850°C. It is shown that, under an appropriate Pb potential, the 2223 phase grows from the amorphous phase via the intermediately formed 2212 phase, but does not grow when the 2212 phase is formed prior to the Pb treatment. The effects of heating rate and film thickness on the growth of the 2223 phase are discussed.
Reactive Ion-Beam Etching of InP with Cl2
Authors: Mutoh Katsuhiko , Nakajima Masato , Mihara Minoru
Published: February 2005

Reactive ion-beam etching (RIBE) of InP with Cl2 at room temperature has been studied by varying the ion extraction voltage and the gas pressure. The sputtering yield is found to increase linearly with the ion extraction voltage above a threshold voltage. RIBE with a higher Cl2 gas pressure is dominated by the chemically reactive etching, and offers a higher etch rate and a smoother surface. Smooth surfaces with low concentrations of residual Cl atoms are obtained under the ion extraction voltage of 400 V and Cl2 gas pressure of 2.5×10-3 Torr.
Cross-Sectional X-Ray Topographic Study of Lattice Distortion in Silicon Crystals with Oxide Film
Authors: Nishino Yoichi , Isomae Seiichi , Horiuchi Masatada
Published: February 2005

Cross-sectional X-ray topography, in which a specimen is prepared as a thin section perpendicular to the specimen surface, is proposed to qualitatively evaluate depth profiles of lattice distortion. The topographs obtained in a silcon wafer with an oxide film show a black speck near the film edge. Such a diffraction image is observed to be apparently deflected as a consequence of strain relaxation caused by the surface effect on the cross sections.
Experimental Study on the Spatial Correlation Properties of Speckled Speckles Using Digital Speckle Photography
Authors: Iwai Toshiaki , Shigeta Kazuyuki
Published: February 2005

This paper experimentally investigates the spatial correlation properties of the speckled-speckle pattern produced from a cascade of two diffusers under laser beam illumination. The experiments were conducted by means of digital speckle photography. The experimental results show that the spatial correlation state of the speckled speckles depends not only on the surface roughness of the diffuser used to produce the speckle illumination but also on the distance z between two diffusers. As such, the dependency can be fairly well interpreted by introducing the concepts of the specular beam and the speckle beam to the illuminating speckle field which consists of the specular and diffuse components.
Analyses of Phase-Matching for Noncollinear Three-Wave Mixing in Uniaxial Crystals
Authors: Bhar G. C. , Chatterjee U.
Published: February 2005

Noncollinear phase-matching for three-wave mixing in uniaxial crystals is studied theoretically. A very simple relation correlating the noncollinear angle with the phase-matching angles of the interacting beams emerges for noncollinear difference-frequency mixing similar to second harmonic generation and sum-frequency mixing.
Waveforms of Prebreakdown Primary Streamers in a Short Positive Point-Plane Gap in Air
Authors: Inoshima Masayuki , Černák Mirko , Hosokawa Tatsuzo
Published: February 2005

Current pulses of single and repetitive prebreakdown streamers have been measured in a positive point-plane gap in dry air at pressures of 3.33–26.7 kPa and at various overvoltages. The pulses of the single streamers exhibited a complex double-peaked form and, in contrast to the commonly held belief, differed significantly from those of the repetitive streamers. To explain the complex waveforms observed, a qualitative physical picture of the processes occurring during the streamer-cathode contact is outlined.
A Method for Measuring Electron Energy Distribution in a Plasma Focus
Authors: Hirano Katsumi , Kaneko Isao , Shimoda Katsuji , Yamamoto Toshikazu
Published: February 2005

A magnetic energy analyzer is designed for pulsed energetic electron beams, and successfully used to obtain energy distribution of the electron beam generated by a plasma focus device. In order to provide quick access of the electron energy distribution in a single shot, an electron detection system consisting of an MCP (microchannel plate) and a PCD (plasma-coupled device) linear image sensor is developed. Sensitivity calibration of the system is carried out using the nuclear emulsion sensitive to energetic electrons. Energy resolution and dynamic range of the detector are presented as functions of the electron energy. The major part of the energy-distributed electrons generated by the plasma focus device are in the relativistic region extending to higher than 1 MeV. The acceleration mechanism of those electrons up to such a huge energy is discussed.
Lifetime Measurements for KrF Excimer Using Photoassociative Pumping
Authors: Hakuta Kohzo , Fujino Masashi , Nakayama Kunihiko , Takuma Hiroshi
Published: February 2005

Various kinetic parameters of the KrF excimer generated by the use of photoassociative pumping have been measured under simple and controllable conditions. The population transfer rate coefficient between the B2Σ+ and C2Π states has been directly determined to be (1.2±0.3)×10-10 cm3/s for Kr buffer gas. The radiative lifetime of the C2Π state and the quenching rate coefficients for F2 and Kr gases are also given as 60±10 ns, (2.5±1)×10-10 cm3/s, and (7±3)×10-12 cm3/s, respectively.
Determination of Spatial Electric Field/Charge/Potential Distributions in Polymer Film Using an Acoustic Step-Wave Probing Technique
Authors: Takada Tatsuo , Soda Keiichi , Gotoh Kazuo
Published: February 2005

An acoustic step-wave probing technique was used to investigate the electric field, charge and potential distributions in insulating materials subjected to a high dc electric stress (104∼105 V/cm) for the temperature of the samples (20∼85°C). The acoustic step pressure was generated by applying a step high voltage (rise time<10 ns, 3 kV) to a piezoelectric transducer of LiNbO3. We obtained the profile of the electric field, charge and potential distributions in a sample using the deconvolution technique.
Experimental Study of the Mechanism of Skiing Turns. II. Measurement of Edging Angles
Authors: Sahashi Toshio , Ichino Shoji
Published: February 2005

In the previous paper, we showed that the edging angle of the ski is one of the basic factors contributing to skiing turns. In this paper, we conducted a quantitative evaluation of edging angles and measured the geometrical parameters of a sliding ski. We found that when a line perpendicular to the direction of movement of the ski within the bottom of the ski (on the plane of the trace) was horizontal, the ski made a straight descent, while when the line had a positive or negative angle from the horizontal plane, it showed a right or left turn, respectively.
Spectral Broadening Error Caused by the Specularly Reflected Beams from Channel Wall in Laser Doppler Velocimetry
Authors: Okada Eiji , Nakajyo Yoshitaka , Fukuoka Yutaka , Yauchi Hitoshi , Minamitani Haruyuki
Published: February 2005

Theoretical and experimental investigations were carried out in respect to the influence of spurious spectra caused by specular reflection in laser Doppler velocimetry. In the measurement of the flow in a thin channel, the multiply reflected beams from channel walls work as incident beams to moving scatterers. The resultant scattered light, whose frequency is shifted by the Doppler effect, causes spurious spectra. The frequencies of the spurious spectra caused by specular reflection are closely related to the geometrical arrangement of the reflecting media such as channel walls. On the other hand, the frequencies are absolutely independent on the position of photodetector and the aperture size of receiving optics. These characteristics are entirely different from the spurious spectra caused by the scattered light from channel walls. The spurious spectra by specular reflection cause the spectral broadening and increase the ambiguity of the Doppler frequency, and its influence cannot be ignored when the receiving optical system is arranged in the backscattering region.
Magnetic Properties of Nonequilibrium Fe-Pd Alloys Produced by DC Triode Sputtering
Authors: Sumiyama Kenji , Fujimori Hiroyasu , Kataoka Noriyuki , Kim Jai Young , Zhang Sheng Liang
Published: February 2005

Fe1-x
Pd
x
alloys have been produced by DC triode sputtering. The single bcc phase is obtained for x=0-0.25. With increasing χ, the lattice constant, a, increases, while the magnetization, I
s, monotonically decreases, where the estimated I
s value for Fe is about 1800 G, being larger than that of pure Fe. The a and I
s increase by annealing below 500 K and decrease by annealing above 500 K. The d-spin band polarization of Fe atoms is probably enhanced by both the lattice expansion and the increase in the Pd atom number at the nearest-neighbor sites of Fe atoms. Since the magnetostriction increases and the coercive force, H
c, decreases with increasing χ, H
c is not dominated by the magnetoelastic interaction but is suppressed by the reduction of crystal grain size. By annealing above 600 K, H
c rapidly increases due to the precipitation of the ordered FePd phase.
Precipitation of Mayenite in 60CaO·35Al2O3·5Fe2O3 Glass Annealed at Several Temperatures Below and Above the Glass Transition Temperature
Authors: Nishida Tetsuaki , Ide Hiroshi , Shinmyozu Teruo , Takashima Yoshimasa , Matsumoto Yasukuni
Published: February 2005

The Mössbauer spectrum of 60CaO·35Al2O3·5Fe2O3 glass annealed at 740-880°C consists of an intense doublet (δ: 0.16 mm·s-1, Δ: 1.67 mm·s-1, Γ: 0.41 mm·s-1) and a weak doublet(δ: 0.13 mm·s-1, Δ: 0.66 mm·s-1, Γ: 0.49 mm·s-1). The Γ of intense doublet (0.41 mm·s-1) is much smaller than that of the original glass (0.65 mm·s-1), whereas the Δ (1.67 mm·s-1) and T
g (844°C) are much greater than those of the original glass (Δ: 1.29 mm·s-1, T
g: 770°C). XRD and IR studies of annealed glasses revealed a precipitation of mayenite (12CaO·7Al2O3) in the glassy phase. The intense and the weak doublets observed in the Mössbauer spectra are attributed to the mayenite and the glassy phase, respectively. The T
g of glass-ceramics is expressed by T
g=aΔ+b, in which “a” and “b” are 200°C·mm-1·s and 510°C, respectively.
Magnetic Field Structure near the Plasma Boundary in Helical Systems and Divertor Tokamaks
Authors: Nagasaki Kazunobu , Itoh Kimitaka
Published: February 2005

The magnetic field structure of the scrape-off layer (SOL) region in both helical systems and divertor tokamaks is studied numerically by using model fields. The connection length of the field line to the wall, L, is calculated. In helical systems, L has logarithmic properties in the SOL region. The effect of axisymmetric fields on the field structure is determined. In divertor tokamaks, L also has logarithmic properties near the separatrix. Even when the perturbations which resonate to rational surfaces near the plasma boundary are added, the logarithmic properties are not changed. The connection length of torsatron/helical-heliotron systems is compared with that of divertor tokamaks.
Admittance Spectroscopy of ZnO Crystals
Authors: Kanai Yasuo
Published: February 2005

To study the native center with the deep energy level in ZnO crystals, the experiment of admittance spectroscopy was performed for Au–ZnO Schottky diodes. The results agree fairly well with the theory of admittance spectroscopy, and by analysing the experimental data, the following results are obtained. The deep energy level is located at about 0.3 eV below the bottom of the conduction band. The electron-capture crosssection and the concentration of the center are found to be of the order of 10-15 c2 and 1017 cm-3, respectively.
Interfacial Charge and Its Effects on Mobility and Carrier Concentration for High-Purity GaInAs Grown by Metalorganic Chemical Vapor Deposition
Authors: Eguchi Kazuhiro , Kushibe Mitsuhiro , Funamizu Masahisa , Ohba Yasuo
Published: February 2005

Carrier concentration and mobility for the MOCVD-grown high-purity GaInAs epilayers on InP were investigated. A thin conductive layer with a sheet carrier concentration of 3.8×1011 cm-2 was considered to exist at the GaInAs and InP heterointerface, because of the GaInAs epilayer thickness dependence of sheet carrier concentration measured by the Hall measurements for GaInAs epilayers on InP. The Hall measurements for the bare GaInAs epilayers, which were prepared by removing the InP, were considered preferable for obtaining the carrier concentration of the high-purity GaInAs epilayers. From the data obtained for the bare GaInAs epilayers, triethylgallium was found to be a more preferable gallium source than trimethylgallium to grow high-purity GaInAs.
Pulse Injection-Locked TEA CO2 Laser for Long Pulse Operation with Feedback Stabilization
Authors: Sasaki Koichi , Ohno Hirotaka , Tsukishima Takashige
Published: February 2005

Stable, long pulse operation of a TEA CO2 laser is achieved with a pulse injection locking system using a hybrid CO2 laser as an injection source. With feedback stabilization loops incorporated, both single-longitudinal- mode and two-longitudinal-mode oscillations are realized. The optimum condition for the synchronization between the injection pulse and the initiation of the discharge of the main TEA CO2 laser is investigated. The effect of the detuning angle on the long pulse operation is also studied.
Role of Zn Impurities in CuGaS2 at Relatively Low Concentrations Revealed by Photoluminescence Measurements
Authors: Ooe Akihiro , Iida Seishi
Published: February 2005

Photoluminescence spectra were studied for Zn-doped CuGaS2 crystals prepared by the iodine transport method from sources satisfying the (CuGaS2)1-x
–(2ZnS)
x
(x=0.00025, 0.0005) relation. These crystals showed three donor-acceptor pair emissions. Analyses of the time-resolved spectra during decays of these emissions indicated the existence of several isolated levels, i.e., a common shallower level of ∼70 meV and three deeper levels of ∼120, ∼155 and ∼204 meV. Considering the possible defect formations in the crystals under the present preparation condition, the origin assignments of these levels were made as follows. The level of ∼70 meV and that of ∼120 meV are due to ZnCu donors and ZnGa acceptors, respectively. One of the levels of ∼155 and ∼204 meV is due to ZnCu–VGa acceptors and the other is due to VGa acceptors.
Anisotropy of Absorption and Photoluminescence Spectra of Stretched Poly(3-alkylthiophene)
Authors: Onoda Mitsuyoshi , Manda Yasuhisa , Yoshino Katsumi
Published: February 2005

The remarkable anisotropy of absorption and photoluminescence spectra has been observed in stretched poly(3-alkylthiophene). Upon stretching at room temperature, the absorption spectral peak shifts to a higher energy and the photoluminescence is enhanced. The absorption spectral shape depends on the polarization of light relative to the stretching direction. The luminescence intensity polarized parallel to the stretching direction is enhanced upon stretching but that of perpendicular polarization is suppressed. That is, intrachain excitation and intrachain recombination are mainly responsible for photoluminescence. The excitation spectrum is also found to be dependent on the observed wavelength of luminescence. These results can be explained in terms of the formation of new twisted bonds between neighboring thiophene rings and the confinement of excited species in the narrow excited region on the main polymer chains.
Polarity Effects on the Corona and Breakdown of Mixture (SF6/N2) in a Needle-Plane Gap under Pulse Voltage
Authors: Nakayama Hiroshi , Onoda Mitsuyoshi , Kuroda Shigeji , Amakawa Kiyoshi
Published: February 2005

The polarity effects of the corona and the breakdown characteristics of mixtures (SF6/N2) were investigated in the needle-plane gap, using pulses with various rise times. The polarity effects were remarkable both on the corona initiation and breakdown voltages. Several bright spots were seen on the negative needle surface. Negative breakdown voltage, especially under pulses with short rise time, was higher than the positive breakdown voltage.
Laser Interferometer for Studying Phase Delay of Piezoelectric Response
Authors: Pan W. Y. , Wang H. , Cross L. E.
Published: February 2005

A laser interferometer was used to study the phase delay of converse piezoelectric response. The real and imaginary parts of the piezoelectric coefficients were calculated from the measured strain amplitude and the phase delay of the strain with respect to the applied electric field for PZT-5 ceramics. The same coefficients were also calculated from measured resonance properties by using Smits's iterative method. The results were in good agreement. The phase delay of the strain with respect to the applied electric field was also studied near resonance frequencies; the result was in excellent agreement with the classic vibration theory.
Nonseeded Crystalline Orientation Control for Si-on-Insulator Laser Recrystallization
Authors: Ogura Atsushi
Published: February 2005

The orientation control technique for Si-on-insulator fabrication by laser recrystallization with artificial seeds, called 2-step laser annealing, is demonstrated. In this technique, a crystalline substrate is not used as a seeding material. Where the controllability is defined as the probability of having the orientation within 20° from (100), 94% controllability was successfully achieved for artificial seeds, and at a distance of 50 µm from the sseds, controllability was 73%.
Statistical Origin of the Meyer-Neldel Rule in Amorphous Semiconductor Thin Film Transistors
Authors: Kikuchi Minoru
Published: February 2005

The origin of the Meyer-Neldel (MN) rule [G
0∝ exp
(A
E
σ)] in the dc conductance of amorphous semiconductor thin-film transistors (TFT) is investigated based on the statistical model. We analyzed the temperature derivative of the band bending energy eV
s(T) at the semiconductor interface as a function of V
s. It is shown that the condition for the validity of the rule, i.e., the linearity of the derivative deV
s/dk
T to V
s, certainly holds as a natural consequence of the interplay between the steep tail states and the low gap density of states spectrum. An expression is derived which relates the parameter A in the rule to the gap states spectrum. Model calculations show a magnitude of A in fair agreement with the experimental observations. The effects of the Fermi level position and the magnitude of the midgap density of states are also discussed.
Crystallinity of GaN Film Grown by ECR Plasma-Excited MOVPE
Authors: Sato Hirotsugu , Sasaki Toru , Matsuoka Takashi , Katsui Akinori
Published: February 2005

In the ECR plasma-excited MOVPE of GaN film, a strong correlation was found between carbon incorporation into the film and the crystallinity change from single crystal to polycrystal. Mass spectroscopic analysis showed that undissociated TMGa in the ECR plasma played an important role in the crystallinity change mechanism.
Co-P Electrodeposited Alumite Films with In-Plane Magnetization
Authors: Daimon Hideo , Kitakami Osamu , Inagoya Osamu , Sakemoto Akito , Mizushima Kunio
Published: February 2005

The magnetic properties and corrosion resistance of a magnetic alumite film, in which micropores are filled with Co, are investigated. It is found that in-plane magnetizatlon film is obtained by adding a small amount of P to the Co. For example, the effective anisotropy energy of the film changes from +0.44×105 erg/cm3 to -1.32×105 erg/cm3 by the addition of 8 at.% P. The in-plane coercivity of the film can be controlled between 340 Oe and 1350 Oe by the P content. The corrosion resistance of the film filled with Co94P6 under the atmosphere of 40°C, 90% R. H. with 10 ppm SO2 gas is tested. The corrosion resistance of the film under this condition is superior to that of sputtered Co-Ni thin film media with a carbon protective layer. Magnetic alumite film filled with Co-P alloy is considered to be a candidate for longitudinal magnetic recording media.
Selective Chemical Etching of Latent Compositional Microstructures in Sputtered Co-Cr Films
Authors: Takahashi Masaya , Maeda Yasushi
Published: February 2005

We examine the validity of a chemical etching method to reveal latent compositional microstructures in a sputtered Co-19.7 at% Cr film. Using dilute aqua regia as the etching solution, changes in the microstructure, composition and chemical state of Co and Cr through chemical etching are investigated. It is observed that the chemical etching progresses from the film surface towards the bottom, revealing an in-grain microstructure comprising periodic stripes (about 8-nm periodicity). The etching causes an increase in Cr and O content and the preferential formation of Cr oxide. These results suggest that the latent compositional microstructure is revealed by selective chemical etching due to the passivation of Cr-rich regions resulting in the preferential dissolution of Co-rich regions.
Effect of Magnetic Inhomogeneity on Magnetization Reversal in Sintered Nd-Fe-B Magnet –Numerical Approach–
Authors: Fukunaga Hirotoshi , Fukuda Takafumi
Published: February 2005

The effect of magnetic inhomogeneity on the magnetization reversal process in a sintered Nd-Fe-B magnet was calculated numerically according to the model where the magnetic anisotropy and the exchange interaction decrease on envelopes of Nd2Fe14B grains. The coercivity in the simulated magnet is determined by the nucleation of a domain wall. Although a local decrease in the anisotropy reduces the nucleation field considerably, a decrease in the exchange interaction has no significant effects on it. The simulated coercive force and its angular dependence can be roughly fitted to the experimental results by assuming that the anisotropy constant is reduced in the 30∼50 Å surface region of Nd2Fe14B grains.
Influence of Paired Mn2+ Centers on the Luminescence Spectra of CaS:Mn2+
Authors: Yamashita Nobuhiko , Maekawa Shuji , Nakamura Kaizo
Published: February 2005

The photoluminescence decay of the CaS:Mn2+ phosphor activated with a fairly large amount of Mn2+ (1-2mol%) consists of slow (8.5 ms at 80 K) and fast (550 µs at 80 K) exponential decay components due to the single and paired Mn2+ centers, respectively. From the measurements of time-resolved emission spectra, the emission bands due to the single and paired Mn2+ centers were found to be located at 590 and 599 nm, respectively, at 80 K. Five bands in the time-resolved excitation spectrum of the paired Mn2+ center are observed on the slightly low-energy side relative to those of the single Mn2+ center. The time-resolved excitation spectra were also investigated for SrS:Mn2+ phosphor.
Change of Surface Electronic States Induced by Li and K Adsorption on the Si(111)7×7 Structure
Authors: Tezuka Yoshihiro , Daimon Hiroshi , Ino Shozo
Published: February 2005

The change of the surface electronic states induced by Li and K adsorption on the Si(111)7×7 surface has been studied using angle-resolved ultraviolet photoelectron spectroscopy. It has been found that with increasing Li coverage, the photoemission intensity of the surface states due to dangling bonds of the 7×7 structure decreases monotonously. However, for K adsorption, the photoemission intensity of the metallic surface state increases at the initial stage. This implies that the 4s electron of a K atom is transferred into the half-filled surface state of the 7×7 structure.
Low Temperature (∼420°C) Epitaxial Growth of CaF2/Si(111) by Ionized-Cluster-Beam Technique
Authors: Watanabe Masahiro , Muguruma Hitoshi , Asada Masahiro , Arai Shigehisa
Published: February 2005

A CaF2 single crystal has been grown on Si(111) by ionized cluster beam (ICB) epitaxial technique at a low temperature of around 420°C. A streaky reflection high energy electron diffraction (RHEED) pattern was observed for layers grown with electron ionization current I
e=400 mA, whereas the pattern was ring-shaped when I
e=100 mA. The acceleration voltage dependence of crystallinity was obtained by Rutherford backscattering spectroscopy, and the most suitable acceleration voltage for crystallinity was found to be V
a=1-2 kV at I
e=400 mA.
Studying the Effect of Sunlight on Etching Characteristics and Response of the CR-39 Track Detector
Authors: Kudo Matiullah
Published: February 2005

The effect of sunlight on the etching characteristics and response of the CR-39 detector is studied. Our results indicate that sunlight significantly affects both the etching charcteristics and sensitivity of the deterctor. The detector response to about 6.1 MeV α particles and neutrons from an Am-Be source drops by about 51% and 87%, respectively, after six months of exposure to sunlight.
In Situ IR Spectroscopic Observation of a-Si:H(F) Films Growing under Spontaneous Chemical Deposition Method
Authors: Wadayama Toshimasa , Kayama Hideki , Hatta Aritada , Suëtaka Wataru , Hanna Jun-ichi
Published: February 2005

Polarization modulation infrared spectroscopy has been applied to in situ observation of a-Si:H(F) films deposited by the spontaneous chemical deposition (SCD) method. The film showed multiple IR absorption bands due to the formation of various hydrogenated and fluorinated silicon species. These bands increased in intensity with deposition time, although the rates of intensity increase of the bands were different from each other. The absorption intensity change of these bands with the deposition time suggests that the predominant species in the initial stage of the deposition is fluorinated silicon. The exposure to air of the film deposited at a low substrate temperature resulted in the remarkable intensity decrease of the bands due to fluorinated silicon, accompanying the appearance of the Si–O stretching band.
Effect of Arsenic Pressure on Donor and Acceptor Concentration in Si Doped MBE GaAs Layers
Authors: Chaix Catherine , Radisson Alain , Contour Jean-Pierre , Neu Gérard
Published: February 2005

The influence of As/Ga flux ratio on the transport and optical properties of high purity Si-doped MBE GaAs has been investigated using two arsenic cells alternately or simultaneously. When the As produced from one cell increases by one order of magnitude, the 77 K Hall mobility decreases from 127000 to 75000 cm2V-1s-1 as the carrier concentration increases from 2.9×1014 to 1.1×1015 cm-3. When two arsenic cells instead of a single one are used simultaneously at lower temperature, the Hall mobilities are around 10% lower for equivalent free carrier concentrations.
Critical Current Densities in Superconducting Y–Ba–Cu–O Prepared by Chelating Method
Authors: Fujisawa Tadashi , Takagi Akira , Okuyama Katsuro , Ohshima Shigetoshi
Published: February 2005

The critical current of superconducting Y–Ba–Cu–O (YBCO) compounds prepared by the chelating method was investigated. The chelating agents used for this study were iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) and triethylenetetraminehexaacetic acid (TTHA). The precursor YBCO obtained from metal complexes heving large stability constants, such as HEDTA, EDTA, DTPA, and TTHA, had very fine and homogeneous particles. The critical current density of YBCO in a block of 1×4×15 mm3 which was sintered at 880∼910°C for 24 h, and then anealed at 500°C in O2 flow was estimated to be 500 A/cm2 at 77 K in zero applied magnetic field.
Microstructural Study of Electroless-Plated CoNiReP/NiMoP Double-Layered Media for Perpendicular Magnetic Recording
Authors: Osaka Tetsuya , Matsubara Hiroshi , Homma Takayuki , Mitamura Satoshi , Noda Kazuhiro
Published: February 2005

The microstructure of the electroless CoNiReP/NiMoP double-layered media was examined with various methods, focusing upon that of the in-plane anisotropy initial regions of the CoNiReP recording layers, and the origin of the initial region was discussed. It was confirmed that the initial region consists of randomly oriented fcc crystallites with Nirich composition, showing the granular condition, while the upper region with the perpendicular anisotropy consists of <002> perpendicularly oriented hcp crystallites, forming the columnar structure with 20- to 30-nm diameter. It is considered that the formation of the initial region is due to a preferential deposition of Ni onto the NiMoP underlayers, and that the thickness of the initial region changes due to a change in the condition of the NiMoP underlayers, especially that of surface activity and/or morphology at their surfaces.
Comparison of Experiment and Theory in a Synchronously Mode-Locked NaCl:OH- (F2
+)H Color Center Laser
Authors: Kurobori Toshio , Aoki Kazumasa , Segawa Toshikazu , Takeuchi Nozomu
Published: February 2005

We report a detailed comparison of experiment and theory of a synchronously mode-locked NaCl:OH- (F2
+)H color center laser. In particular, we show the dependence of the steady-state pulse-shaping dynamics on the pump pulse power, loss coefficient and pump pulse width. Additionally, we also present a comparison of the mode-locking characteristics of an NaCl:(F2
+)H laser and a KCl:Tl0(1) laser.