bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of HF-treated Si(111) Surfaces
Authors: Konishi Tomohiro , Uesugi Katsuhiro , Takaoka Katsuya , Kawano Seiji , Masamichi Yoshimura Masamichi Yoshimura , Takafumi Yao Takafumi Yao
Published: February 2005

The properties of Si(111) surfaces treated in various HF solutions are characterized by photoluminescence (PL), scanning tunneling microscopy (STM) and Fourier-transform infrared spectroscopy (FTIR). STM images show that the surfaces dipped in normal HF solution are terminated by Si-H, Si-H2 and Si-H3 bonds with high step density, while those treated by pH-modified buffered HF are atomically flat with wide terraces terminated mostly by Si-H bonds. Multistage oxidation processes via surface defects, atomic steps, kinks or terraces are suggested by a change in the PL intensity of HF-treated Si surfaces with exposure to oxygen. The PL measurement also shows that the surface treated with pH-modified buffered HF or boiled deionized water shows much better stability against oxidation than conventional HF-treated Si surfaces, which is consistent with the surface structure observed by means of STM.
Submicron Particles Observed during Etching Process
Authors: Morita Yoshimitsu , Yamaguchi Masanori , Nitami Shinya Iida
Published: February 2005

Submicron particle counts were taken by monitoring hole etching in the RIE (reactive ion etching) process for approximately 30 days. One particle sensor was installed in the exhaust pipe from a process chamber and the second one in the exhaust pipe from loadlock chambers. More than 1000 wafers were processed using five different etching processes. Differences in the particle count per minute were observed among the etching processes. Reactive gas pressure, 13.56 MHz rf power and gas composition significantly influenced the generation of particles. The particle count rate increased as the etching time for one wafer increased. A large number of holes were observed on the etched photoresist surface with a scanning electron microscope (SEM) after prolonged etching time.
Influence of Sputtering Conditions on the Characteristics of Superconducting Y-Ba-Cu-O Films
Authors: Kobayashi Tadayuki , Eto Satoshi , Kato Yoshihito , Kouichi Usami Kouichi Usami , Toshinari Goto Toshinari Goto
Published: February 2005

Influences of the substrate holder bias voltage V
H, the oxygen partial pressure P
O2, and the distance D between the substrate and the target on the superconducting characteristics of Y-Ba-Cu-O thin films were investigated. The optimum bias voltages were from -10 V to -20 V for total gas pressure P=300-500 mTorr. With increasing distance at P=500 mTorr, the critical temperature T
c increased and the c-lattice parameter c
0 decreased. However, at D longer than 50 mm, the values of T
c and c
0 did not depend on D. These films have the maximum T
c of 90 K and the c-lattice parameter ranging from 1.167 to 1.169 nm. These results imply that the sputtering conditions of P
O2≥300 mTorr, V
H of -10 V to -20 V and D>5 cm at 500 mTorr are necessary for fabricating the films having T
c of 87-90 K by means of on-axis rf magnetron sputtering having a YBa2Cu3O
z
target.
Structure and Lattice Deformation of Ce-Substituted Yttrium Iron Garnet Film Prepared by RF Sputtering
Authors: Mino Shinji , Tate Akiyuki , Uno Takehiko , Toshihiro Shintaku Toshihiro Shintaku , Atsushi Shibukawa Atsushi Shibukawa
Published: February 2005

We investigated the structure and lattice deformation of CeY2Fe5-δO12-Z
(Ce1·YIG) film prepared by RF sputtering. We found that the lattice constant parallel to the film plane a
// is equal to the lattice constant of the substrate a
s. This shows that this Ce1·YIG film belongs to Region I in the Besser model. Some Ce1·YIG films become a double-layer structure as the lattice constant mismatch ||
Δa||
increases. This change in the film structure caused by ||
Δa||
is very different from that of LPE film. In a Faraday rotation θF spectrum of single-layer films deposited on GCGMZG and GGG substrates, the θF dispersion around 800 nm is shifted to the longer wavelength side. We consider this θF shift around 800 nm to be induced by the difference in the film deformation.
Origin of the Long-Wavelength-Side Peak in AlxGa1-xAs:Si Light-Emitting Diodes
Authors: Park Seounghwan , Gho Seokjung , Choe Byungdoo
Published: February 2005

The origin of the long-wavelength-side peak (peak B) in Al
x
Ga1-x
As:Si light-emitting diodes is studied by investigating the relationships between radiative spectra and spatial distribution of the luminescence. Peak B originates from a recombination barrier existing in the P-Po boundary. Invariance of the energy of peak B independent of injection level can be explained by the dominance of the band-impurity (BI) transition in the P-Po boundary.
Stress in Thin Micro-Zone-Molten Crystalline Silicon Films on Solid Substrates
Authors: Paul W. Mertens Paul W. Mertens , Herman E. Maes Herman E. Maes
Published: February 2005

Thin crystalline silicon films supported by a substrate can be obtained by zone melting recrystallization. In this study a model for the stress generated in the substrate during this process and for the final stress in the thin silicon film is presented. For a given structure the stress is determined by the preheating temperature only. In the substrate compressive stress is induced by the localized heating inherent to the ZMR process. The moving heater introduces a tensile stress component in the final SOI film. If a line shaped heat source is used, this tensile stress is non-equi-axed. The presented model can account for a wide variety of reported experimental results.
Ni-Silicide Formation: Dependence on Crystallographic Orientation of Si Substrates
Authors: Yamauchi Shoichi , Hirai Masaaki , Kusaka Masahiko , Iwami Motohiro , Nakamura Hatsuo , Yokota Yasuhiro , Akiyama Akitsugu , Watabe Hirokuni
Published: February 2005

We have analyzed the influence of the crystalline orientation of Si substrates on Ni-silicide formation. Ni-silicide/Si(111) and (100) samples formed through solid-phase reaction (SPR) were examined using soft X-ray emission spectroscopy (SXES), transmission electron microscopy (TEM) and grazing incidence X-ray diffraction. The formation of δ-Ni2Si and NiSi on Si(100) substrate occurs at a lower temperature than that on Si(111). However, the NiSi2 region is found to be formed only on the Si(111) substrate at a lower temperature (T
a=500°C) than previously reported. The NiSi2 regions are located at the interface region of NiSi/Si(111) and have a small island structure. On Si(100) substrates, only the NiSi layer is stably formed in the heat-treatment temperature range of 250-700°C.
Real-Time Observation of (1×1)-(7×7) Phase Transition on Vicinal Si(111) Surfaces by Scanning Tunneling Microscopy
Authors: Suzuki Mineharu , Hibino Hiroki , Homma Yoshikazu , Fukuda Tsuneo , Sato Tomoshige , Iwatsuki Masashi , Miki Kazushi , Tokumoto Hiroshi
Published: February 2005

Scanning tunneling microscopy of a Si(111) surface with a misorientation of 10° reveals that the (7×7) domains form stripes whose widths are quantized in units of a (7×7) unit cell. The (7×7)-to-(1×1) phase transition on this surface occurs at about 1030 K when the temperature is increased, which is about 80 K lower than that for a nominally flat Si(111) surface, and the (1×1)-to-(7×7) phase transition occurs at 1003 K when the temperature is reduced. Nucleation and growth of (7×7) domains are explained in terms of the domains' energy gain and the energy loss of the domain edges and slant surfaces.
Effects of Beam Size on Beam Position Measurements Made with Electrostatic Monitors
Authors: Takafumi Nakagawa Takafumi Nakagawa , Shuhei Nakata Shuhei Nakata
Published: February 2005

A beam position monitor was used to measure beam position in an accelerator. The monitor was calibrated using an antenna with a 2 mm diameter to simulate an electron beam. However, the beam was large due to horizontal multiturn injection. Therefore, the measurements of beam position were affected by beam size, and measurement errors arose. When there were large errors, it was difficult to correct closed orbit distortion from the ideal orbit and to improve the performance of the accelerator. The effect of beam size on the measurements was simulated by means of the boundary element method. The results showed that beam position measured with monitors was increased vertically and decreased horizontally in relation to the actual beam position. These results were verified by experiments in a synchrotron.
Lower Hybrid Plasma Heating with Anisotropic Temperature
Authors: Rapozo Cândido da Cunha , Antonio Serbêto Antonio Serbêto , Lindolff Thadeu Carneiro Lindolff Thadeu Carneiro
Published: February 2005

Experimental results on RF power absorption due to lower hybrid resonance with anisotropic plasma temperature are presented. It has been shown that when the wave vector is transverse to the applied magnetic field, the plasma heating occurs along the perpendicular direction where the anisotropy in the temperatures was expected. Drift wave was observed and it led to a stochastic heating near the resonance layer causing an isotropy on the temperature.
Cryogenic Neutron Calorimeter II. Deposited Energy and Temperature Increase due to DD Neutrons
Authors: Ido Ryusuke Tsuji
Published: February 2005

This complement to an earlier paper [Jpn. J. Appl. Phys. 23 (1984) 1133] on the cryogenic neutron calorimeter presents the deposited energy and the temperature increase of working materials due to 2.45 MeV deuteron-deuteron (DD) reaction neutrons. In materials (graphite, Be, B, U and Si) cooled to 2 K and placed 10 cm from a fusion pellet (1012 DD neutrons per shot), the temperature increases are found to be 0.167 K, 0.216 K, 2.899 K, 0.424 K, and 0.331 K, respectively.
Holographic Lithography with Endpoint Detection of Resist Development
Authors: Kawata Hiroaki , Nobuo Kasamatsu Nobuo Kasamatsu , Kenji Murata Kenji Murata
Published: February 2005

Grating patterns with a period of about 0.4 µm are fabricated by means of holographic lithography with a He-Cd laser (λ=441.6 nm). In the fabrication process to develop a resist film sample a He-Ne laser beam irradiates the sample and its reflection intensity is observed. The reflection intensity of the He-Ne laser does not change periodically during the development. We calculate the He-Ne laser reflection intensity from the resist grating during the development assuming either the rectangular or the triangular resist grating profiles. The calculated reflection intensity with the triangular profile shows good agreement with the experimental one. The reflection intensity can be applied to the endpoint detection of the development. We have fabricated resist gratings with vertical profiles whose lines and spaces are approximately 0.1 µm and 0.3 µm in width, respectively. Very fine lines of 0.06 µm in width with vertical walls have also been fabricated by controlling the development time. Au gratings with 10 nm thickness can be made directly using the lift-off technique.
X-Ray Photoelectron Spectroscopy and Electrical Characteristics of Na2S-Passivated GaAs Surface: Comparison with (NH4)2Sx-Passivation
Authors: Sato Kenji , Minoru Sakata Minoru Sakata , Hideaki Ikoma Hideaki Ikoma
Published: February 2005

X-ray photoelectron spectroscopic (XPS) analysis was performed for the Na2S-passivated GaAs surface. The XPS data indicated that oxidation of GaAs was not suppressed by Na2S passivation, and fair amounts of As2O3 and Ga2O3 were observed after exposure to air for 3 days in contrast with the case of (NH4)2S
x
passivation. However, segregation of elemental arsenic was found to be substantially suppressed by this passivation. Both As
x
S
y
(probably AsS) and As2S3 were observed at the Na2S-passivated surface. This is due to diffusion of elemental As through the thick Na2S film and its reaction with S to produce As
x
S
y
and As2S3, and this is probably the mechanism of suppression of As segregation. After an exposure to air, the XPS signal from As
x
S
y
substantially decreased. This is probably due to the reaction of As
x
S
y
→As2O3+SO2↑. The XPS measurement for the (NH4)2S
x
-passivated GaAs samples indicated that oxidation was strongly suppressed, but segregation of elemental As was not effectively suppressed by this passivation, consistent with the previous data. As-S bonds were found to disappear upon annealing after (NH4)2S
x
passivation. Elemental sulfur was observed after the exposure to air for 3 days for the (NH4)2S
x
-passivated samples. This may be due to breakdown of both As-S and Ga-S bonds accompanying oxidation of As and Ga. Schottky diodes were fabricated on the substrates treated in various ways, and I-V characteristics were measured. From the point of view of degradation due to air exposure, the best result was obtained for the (NH4)2S
x
-passivated sample with annealing.
Excitonic Electroabsorption in Solid Solution of CdxZn1-xS Single Crystals
Authors: Muhamad Rasat Muhamad Muhamad Rasat Muhamad
Published: February 2005

Excitonic electroabsorption (EA) of Cd
x
Zn1-x
S (x=1.0, 0.8, 0.7 and 0.0) solid solution single crystals was investigated at 150 and 77 K. The EA spectra have been analysed within the context of the Stark theory that enables the lowest bound exciton states in the solid solution at each composition to be located precisely. This allows the determination of the reduced effective mass of the exciton which is found to vary linearly with the optical band gap as predicted theoretically.
Optical Absorption and Electron Spin Resonance in CuAlS2:Ni
Authors: Aksenov Igor , Kai Tetsuya , Nobuyuki Nishikawa Nobuyuki Nishikawa , Katsuaki Sato Katsuaki Sato
Published: February 2005

Electron spin resonance (ESR) and optical absorption spectra have been studied in Ni-doped CuAlS2crystals, grown by the chemical vapour transport technique. Absorption spectra show optical transitions between 3d-shell originated orbitals of the Ni2+ion, as well as charge-transfer transitions Ni3+→Ni2+and Ni2+→Ni+, their intensities being dependent on the position of the Fermi level in the bandgap of the host compound. The ESR results confirm the changes in the relative concentrations of Ni in different charged states caused by the Fermi level shift in the band gap, this shift, in its turn, being caused by thermal treatments of the crystals in various atmospheres.
Polysilicon-Contacted Thin Emitter Thyristors
Authors: Jingping Xu , Yuehui Yu , Peng Shaolian Peng Shaolian , Chen Tao Chen Tao
Published: February 2005

In this paper, we report detailed theoretical analysis of turn-off time and on-state voltage drop in the new type of polysilicon-contacted thin emitter thyristor, studied using the asymmetrical pin diode model and through comparisons with conventional thyristors. The numerical calculations and experimental results showed that for a suitable thickness and total impurity amount of the thin emitter, not only can the turn-off time be shortened by a factor of around 1.5 compared with that of conventional thyristors, but also the on-state voltage drop of the devices is lower than that of conventional thyristors. When the lifetime of the minority carriers in the n
B base was decreased to a suitable value, the turn-off time of the devices could be further shortened, up to 1/2.5-1/3 that of conventional thyristors, without deterioration of the on-state properties. In addition, turn-on properties of the new devices are discussed.
Improvement of Magnetic Properties of Amorphous Ferromagnetic Alloy by Flash Annealing
Authors: Kalyan Mandal Kalyan Mandal
Published: February 2005

The effect of field flash annealing (which combines the application of an electrical current pulse to the sample and the simultaneous application of a longitudinal magnetic field) on the dc magnetic properties of amorphous ferromagnetic Fe40Ni40B20 ribbon is studied. It is found that such a technique can be used to improve the softness in magnetic properties of the alloy when the magnitude of current pulse is less than a certain value, beyond which the sample becomes harder.
Femtosecond Erbium-Doped Fiber Lasers and a Soliton Compression Technique
Authors: Yoshida Eiji , Yasuo Kimura Yasuo Kimura , Masataka Nakazawa Masataka Nakazawa
Published: February 2005

The lasing characteristics of an erbium-doped fiber laser with a nonlinear amplifying loop mirror (NALM) were investigated in detail. The NALM was pumped by 1.48 µm InGaAsP laser diodes and an output pulse as short as 124 fs was obtained at 1.56 µm. The 124-fs pulse was shortened to 50 fs by using adiabatic soliton narrowing and high order soliton compression. Soliton narrowing was achieved by amplifying the soliton pulse adiabatically with an erbium-doped fiber amplifier, and a short length of dispersion-flattened fiber was used for soliton compression. Soliton narrowing enabled us to succeed in generating a 98-fs pulse directly from a modified erbium-doped fiber laser.
Effect of Moisture on Performance of SrS:Ce Thin Film Electroluminescent Devices
Authors: Poelman Dirk , Vercaemst Rita , Meirhaeghe Roland Leon Van , Willy Henri Laflère Willy Henri Laflère , Felix Cardon Felix Cardon
Published: February 2005

Although the continuing research on blue thin film electroluminescence has led to fairly stable and efficient SrS:Ce devices, there is still a lack of fundamental knowledge about the origin of the remaining instability. The purity and stability of both the SrS host semiconductor and the Ce activator have been examined, in the starting materials as well as in the evaporated thin films. It is found that the SrS host is relatively inert, but that it is imperative to choose a moisture-insensitive Ce-based activator.
Optical Constants of Zn1-xCdxTe Ternary Alloys: Experiment and Modeling
Authors: Sadao Adachi Sadao Adachi , Toshifumi Kimura Toshifumi Kimura
Published: February 2005

The optical spectra of Zn1-x
Cd
x
Te ternary alloys in the 1.1-5.6-eV photon-energy range at room temperature have been measured by spectroscopic ellipsometry (SE). The optical constants reported here are the complex dielectric constant (ε=ε1+iε2), complex refractive index (n
*=n+ik), absorption coefficient (α) and normal-incidence reflectivity (R). The measured data are analyzed on the basis of a simplified model of the interband transitions. The experimental data reveal distinct structures in the optical spectra at energies of the E
0, E
0+Δ0, E
1, E
1+Δ1 and E
2 transitions, and are in reasonable agreement with the theoretical model. The model proposed here enables us to obtain the optical response in Zn1-x
Cd
x
Te alloys of arbitrary composition (x) and photon energy (E=\hbarω).
Photoconductivity of Trigonal Selenium under High Pressure
Authors: Nagata Kiyofumi , Akihiro Yoshida Akihiro Yoshida , Yasuhiko Miyamoto Yasuhiko Miyamoto
Published: February 2005

The photoconductivity spectrum of trigonal selenium has been measured at pressures up to about 1 GPa. With increasing pressure, the photocurrent sharp peak near 1.8 eV shifts to the lower energy region at a rate of (1.6±0.1)×10-1 eV/GPa, suggesting that the band gap decreases at this rate with increasing pressure.
The Dependence of the Electrooptical Characteristics of Polymer Dispersed Liquid Crystal Films on Temperature
Authors: Fuh Andy Ying-Guey , Ko Tsung-Chih , Chyr Yeong-Ning , Huang Chi-Yen , Bao-Wen Tzen Bao-Wen Tzen , Chi-Ren Sheu Chi-Ren Sheu
Published: February 2005

The temperature dependence of the static and the transient electrooptical characteristics of polymer dispersed liquid crystal (PDLC) films is reported. The experimental results agree qualitatively with the theory. These suggest that a PDLC film can be used as a temperature sensing material.
Oxygen Doping Mechanism of Semicrystalline Poly-p-Phenylene Sulfide for Novel Photoconductive Polymer Films
Authors: Takimoto Akio , Akiyama Koji , Onomichi Kyoko , Tanaka Eiichiro , Masanori Watanabe Masanori Watanabe , Hisahito Ogawa Hisahito Ogawa
Published: February 2005

The role of oxygen molecules in the marked increase of photoconductivity of poly-p-phenylene sulfide (PPS) films has been studied. Optical, photoconductive and structural studies of PPS films prepared with oxygen doping and/or dedoping processes have clarified the carrier transport mechanism. We have proposed a sensitive model wherein oxygen molecules reversibly doped in the amorphous region of PPS films act as hopping sites for carrier transport. By use of the oxygen-doped PPS film as a carrier transport layer of photoreceptors, the hole transport ability was improved as a result of doping.
Preparation of Polycrystalline Silicon Thin Films by Cathode-Type RF Glow Discharge Method
Authors: Jayatissa Ahalapitiya Hewage , Yoichiro Nakanishi Yoichiro Nakanishi , Yoshinori Hatanaka Yoshinori Hatanaka
Published: February 2005

Polycrystalline silicon films were deposited by the cathode-type rf glow discharge method where a protective mesh against ions was attached to the cathode using 0.5% SiH4 diluted with hydrogen at a pressure of 0.09 Torr. The deposited films were found to be polycrystalline for a wide range of applied rf power (0.05-1 W cm-2) and substrate temperature above 200°C. The crystallization mechanism was suggested to be the surface reaction in the chemical equilibrium state between growth and etching of weak Si-SiH
x
bonds on the growing surface caused by hydrogen radicals in the plasma. Electrical and optical properties of the film suggested that substrate temperatures above 350°C and deposition power densities above 0.5 W cm-2 are suitable for formation of polycrystalline silicon.
Junction Properties of Polycrystalline Diamond/Hydrogenated Amorphous Silicon p-n Heterojunctions
Authors: Kiyota Hideo , Okushi Hideyo , Okano Ken , Akiba Yukio , Kurosu Tateki , Iida Masamori
Published: February 2005

Junction properties of polycrystalline diamond have been studied using heterojunctions between p-type polycrystalline diamond and n-type hydrogenated amorphous silicon (a-Si:H). For the range of resistivity of polycrystalline diamond from 1 Ω cm to 120 Ω cm, current-voltage (I-V) characteristics of the p-n heterojunctions show a distinct rectification and capacitance-voltage (C-V) characteristics show an approximately linear C
-2-V relationship in the reverse bias condition, indicating that the depletion layer occurs in the vicinity of the junction in the same manner as for the conventional crystalline p-n heterojunction. The temperature dependences of I-V and C-V characteristics are described by the conventional heterojunction models proposed for the crystalline semiconductors. These results suggest that junction properties of polycrystalline diamond are not greatly influenced by features of the polycrystalline film, such as grain boundaries and roughness of the surface, although these seem to affect the carrier transport in the polycrystalline network.
Charge Loss Due to AC Program Disturbance Stresses in EPROMs
Authors: Lin Jyh-Kuang , Chang Chun-Yen , Wang Tai-Ho , Huang Heng-Sheng , Chen Kun-Luh , Ho Tai-Shung , Ko Joe
Published: February 2005

Charge loss in interpolyoxide erasable programmable read-only memories (EPROMs) due to program disturbance by alternating current pulses applied to the drain was studied for the first time. It was found that the charge loss due to ac stress is more severe than that due to dc stress. Experimental results reveal that the more positive the floating gate potential, the more severe is the drain ac disturbance observed. The main reason for the charge loss is the displacement current which agitates the charges in the floating gate, creating a leakage path from the floating gate to the drain, in which the drain-to-floating-gate overlapping capacitance C
fd plays an important role. The drain dc stresses of interpolyoxide/nitride/oxide (ONO) EPROMs were also measured under different bias conditions and temperatures. The data show that higher dc electric field of the floating gate to the drain results in larger V
th shift, which can be accelerated by elevated temperature. In addition, the control gate ac stress-enhanced drain dc disturbance was also measured. We proposed that the dc drain stress is applied during the ac gate stress, which results in a heating effect. The results support the concept of dielectric ac heating.
Influence of Oxygen Deficiency on Electrical Properties in the Superconductor (Bi, Pb)2Sr2Ca2Cu3Oy Phase
Authors: Um Woo Sik , Kim Duk Hee , Kim Ho Gi
Published: February 2005

The samples annealed in lower and higher oxygen partial pressure than P
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c shift to the lower temperatures compared with the sample annealed in P
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Polarization Properties in Phase Conjugation with Bacteriorhodopsin
Authors: Okada Yoshiko , Yamaguchi Ichirou , Otomo Jun , Sasabe Hiroyuki
Published: February 2005

Polarization properties of the phase conjugate beam in biological photochrome bacteriorhodopsin with photoinduced anisotropic nonlinearity are studied. We derived the polarization state and reflectivity of the phase conjugate beam in degenerate four-wave mixing (DFWM) where two pump beams have the same or orthogonal polarization and a probe beam has arbitrary polarization. Theoretical results are proved by experiments.
Investigation of Electron Transport Properties of Polyimide Langmuir-Blodgett Films Containing Porphyrin by d2V/dI2-V Measurement
Authors: Wada Masami , Tohru Kubota Tohru Kubota , Mitsumasa Iwamoto Mitsumasa Iwamoto
Published: February 2005

We fabricated junctions with a polyimide (PI) Langmuir-Blodgett (LB) film, and then examined electron tunneling through PI LB films. It was concluded that PI LB films function as good electrical tunneling barriers for inelastic electron tunneling spectroscopy (IETS). We also fabricated junctions with a PI LB film containing porphyrin (PORPI), and then examined the electron transport properties of the junctions by means of IETS measurement. An inelastic tunneling process accompanying by the energy loss due to either the excitation of vibrational modes of porphyrin or the excitation of electronic transitions in porphyrin was observed.
An Anomalous Enhanced Tail Diffusion of Boron in Directly Bonded Samples of Heavily and Lightly Doped Silicon
Authors: Witawat Wijaranakula Witawat Wijaranakula
Published: February 2005

An anomalous enhanced tail diffusion of boron in directly bonded samples of heavily and lightly doped silicon was observed after annealing at temperatures ranging between 1000 and 1200°C. Similar to enhanced diffusion commonly observed in boron ion implanted silicon during implantation damage annealing, enhanced diffusion in directly bonded samples is suggested to be attributed to mobile interstitial boron species. In heavily doped Czochralski grown silicon, interstitial boron species could be produced as a result of an elastic interaction between excess silicon interstitials and substitutional boron atoms during crystal solidification. The enhanced diffusivity correlated from the present results with those observed in boron ion implanted silicon is described by the Arrhenius's equation, 3×10-4 exp (-2.1 eV/kT) cm2/s.
Simple Criterion on Colloid Formation in SiO2 Glasses by Ion Implantation
Authors: Hideo Hosono Hideo Hosono
Published: February 2005

A simple criterion as a first approximation to predict the formation of elementary colloids of implants in SiO2 glasses by ion implantation has been proposed. The criterion predicts that colloid formation occurs when free energy of formation of oxides of implants is greater than that of SiO2 at ∼3000 K, which corresponds to the fictive temperature of implanted layers. The prediction is compared with observations reported so far.
X-Ray Energy Analysis for Radio Frequency Current Drive Experiments in the DIII-D Tokamak
Authors: Kawashima Hisato , Trukhin Vladimir. M. , Lohr John , Harvey Robert W. , James Reed , Luce Timothy C. , Petty Craig C. , Robert I. Pinsker Robert I. Pinsker , Ronald Prater Ronald Prater
Published: February 2005

The X-ray energy spectra were measured during electron cyclotron current drive (ECCD) and fast wave current drive (FWCD) experiments in the DIII-D tokamak. High energy electrons, over 100 keV, were observed during ECCD near the plasma center and enhanced radially by the effect of downshifted frequency. Tail formation with the maximum energy of 50 keV was observed clearly during 2 T, 0.8 MA FWCD experiments. For combined FWCD and ECCD, the bulk heating efficiency was increased over the case with FW only, with ηe∼2.3×1019 m-3 keV/MW, and it was stronger for the counter (CTR) case than the co (Co) case. (Here Co corresponds to the direction of launched wave which will enhance the plasma current. CTR refers to the opposite direction.) However, the coupling of FWs to high energy electrons produced by ECH was stronger for the Co case.
Variations of Mechanical Properties in Egg White during Gel-to-Glasslike Transition
Authors: Koshoubu Nobutatsu , Kanaya Haruichi , Hara Kazuhiro , Taki Seiji , Takushi Eisei , Matsushige Kazumi
Published: February 2005

Simultaneous measurements of weight, volume and mechanical properties have been performed during the gel-to-glasslike transition of heat-treated egg-white gel. Change in the elastic stiffness occurred in three steps: in the initial stage, it remained almost constant, then increased exponentially, and lastly, saturation was attained. The saturation point almost coincided with the characteristic time at which the rates of decrease of the weight and volume changed. In addition, from the time dependence of the differentiated values, the close correlation between the elastic stiffness and weight was revealed. It was also found that the loss of free water induces an increase of about a thousardfold in elastic stiffness of gels during transition.
Thin Film Growth of Pb(Zr, Ti)O3 by Photoenhanced Metalorganic Chemical Vapor Deposition Using NO2
Authors: Shimizu Masaru , Katayama Takuma , Masataka Sugiyama Masataka Sugiyama , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

Ferroelectric Pb(Zr, Ti)O3 thin films were successfully grown by photoenhanced metalorganic chemical vapor deposition (photo-MOCVD), using Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4 and NO2. Both tetragonal and rhombohedral Pb(Zr, Ti)O3 thin films were obtained at substrate temperatures higher than 535°C. Significant effects of photoirradiation on the growth behavior were observed. The observed effects included an increase in the growth rate and film compositional ratio of Zr/(Zr+Ti), and a change in the electrical properties. A decrease in the growth temperature of the Pb(Zr, Ti)O3 films caused by photoirradiation was observed only when the films were grown at low gas supply ratios of [Zr]/([Zr]+[Ti]). The photodeposited Pb(Zr, Ti)O3 films obtained showed good ferroelectric properties, good leakage characteristic and good step coverage.
Preparation and Optical Waveguide Properties of LiNbO3 Thin Films by RF Magnetron Sputtering
Authors: Shimizu Masaru , Furushima Yuji , Takashi Nishida Takashi Nishida , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

C-axis-oriented LiNbO3 films were successfully obtained on ZnO/SiO2/Si, ZnO/glass and Pt/SiO2/Si substrates at substrate temperatures higher than 450°C by RF magnetron sputtering. LiNbO3 films were also grown epitaxially on α-Al2O3(001), (012) and (110) and LiTaO3(110) substrates at substrate temperatures higher than 650°C. The minimum optical propagation loss of the films was 6.47 dB/cm (TE0 mode) for the LiNbO3 film on LiTaO3. An improvement in the optical propagation loss after annealing treatment was observed.
Preparation and Properties of (Ba, Sr)TiO3 Thin Films by RF Magnetron Sputtering
Authors: Noboru Ichinose Noboru Ichinose , Takashi Ogiwara Takashi Ogiwara
Published: February 2005

This paper describes the properties of (Ba0.5Sr0.5)TiO3 thin films prepared on Pd(100)/MgO(100) substrate using the rf magnetron sputtering technique. Perovskite-type thin films were prepared at a gas pressure of 7 mTorr, and the crystal orientations of thin films changed depending on the substrate temperature. The dielectric constant increased with increasing substrate temperature, and the maximum value ∼300 was obtained at 550°C.
Preparation of Dense and Pure Perovskite Ceramics in Pb(Ni1/3Nb2/3)O3-PbTiO3 System
Authors: Takahashi Seiji , Miyao Shuji , Satoshi Yoneda Satoshi Yoneda , Makoto Kuwabara Makoto Kuwabara
Published: February 2005

(1-x)Pb(Ni1/3Nb2/3)O3-xPbTiO3 perovskite ceramics were synthesized by using PbO, NiNb2O6 and PbTiO3 as raw materials. The prepared specimens were dense (RD>95%) and composed of only the perovskite phase. The morphotropic phase boundary between tetragonal and pseudocubic forms in this system existed in the composition range of 0.3<x<0.4. The specimen with x<0.4 exhibited the typical relaxor characteristics.
Core-Shell Domain Structure in Lead Complex Perovskite Material
Authors: Fumio Uchikoba Fumio Uchikoba , Kentaro Sawamura Kentaro Sawamura
Published: February 2005

Core-shell structures in Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Mg1/2W1/2)O3 (PMN-PT-PMW) with 2 wt% excess WO3 were discussed. With microstructural measurements, core-shell structures were observed in almost all grains. The cores, which show ferroelectric fringe patterns, were Nb-and-Ti-rich, while the shells were W-rich, accompanied by clear superlattice diffraction spots. In electrical measurements, the material showed ferroelectric D-E hysteresis loops and frequency dependence of the dielectric constant. These results can be explained by the structure wherein the cores consist of PMN-PT-rich solid solution which has a higher phase transition temperature, and the shells consist of PMW-rich solid solution which has a lower phase transition temperature.
Simulation Study of Phase-Shift Dependence of the Phase Conjugate Wave Intensity in a Photorefractive Medium
Authors: Uesu Shin-ichi Itoh
Published: February 2005

Based on the exact solutions of the coupled-wave equations in the degenerated four-wave mixing process, the behavior of the phase-conjugate wave (PCW) intensity in a photorefractive medium was calculated with varying phase shift φ between the light interference pattern and the refractive index grating, and coupling strength of the wave interaction. The behavior of the PCW intensity was examined in a wider range of φ than the previous reports by other authors. It was found that a multiple-solution region exists at specific values of φ. The fidelity of image reconstruction was discussed based on the results of the dependence of the PCW intensity on the probe beam intensity.
Emission Characteristics of Internally Self-Pumped Phase-Conjugate Wave in Photorefractive KNbO3:Fe and BaTiO3 Crystals
Authors: Aoyama Tsuyoshi , Mizuta Satoru , Kurimura Sunao , Uesu Yoshiaki , Seo Iwao
Published: February 2005

The reflectivity and the response time of the self-pumped phase conjugation in unreduced KNbO3:Fe and BaTiO3 were measured and compared as functions of incident beam intensity, incidence angle and incidence position of the crystal. The self-pumped phase conjugation of KNbO3:Fe was generated in narrow regions of the incidence angle and position, in comparison with that of BaTiO3. It was also observed that the response time of KNbO3:Fe was longer than that of BaTiO3 under the same experimental conditions.
Dielectric Properties in Ferroelectric and Antiferroelectric Liquid Crystals with Isotropic-Chiral Smectic C Phase Sequence
Authors: Uchiyama Yasushi , Moritake Hiroshi , Ozaki Masanori , Yoshino Katsumi , Taniguchi Hiroki , Satoh Kazuo , Tani Takeshi , Fujisawa Koichi
Published: February 2005

Dielectric properties in ferroelectric and antiferroelectric liquid crystals which show isotropic (Iso.)→chiral smectic C (SmC*) and Iso.→chiral smectic CA (SmCA
*) phase transitions have been studied. In the ferroelectric liquid crystal with the Iso.-SmC* phase sequence, two dielectric relaxations are observed under dc bias voltage. One appears around 700 kHz in frequency and is attributed to the soft mode. The other is related to the contribution of the Goldstone mode whose relaxation frequency is increased by the application of bias voltage. The antiferroelectric liquid crystal with the Iso.-SmCA
* phase sequence also has two relaxations in the SmCA
* phase. One originates from the molecular rotation around the short molecular axis and the other may correspond to the soft mode.
Electro-Optic Responses of Antiferroelectric Liquid Crystals with Very Short Reverse Pulse Voltage
Authors: Okada Hiroyuki , Sakurai Tetsufumi , Katoh Toyoaki , Watanabe Manabu , Onnagawa Hiroyoshi , Noriyuki Nakatani Noriyuki Nakatani , Kazuo Miyashita Kazuo Miyashita
Published: February 2005

Electro-optic responses accompanied by field induced phase transitions from the ferroelectric state to the antiferroelectric state have been studied. The response time obtained with very short pulse of reverse polar voltage is seven hundred times as short as that without reverse pulse voltage. From the viewpoint of application, a two-field matrix-addressing waveform is also proposed.
Atmospheric Effect on Wetting of (Pb, La)(Zr, Ti)O3 with Electrode Metals
Authors: Sunao Sugihara Sunao Sugihara , Yoshinori Moriya Yoshinori Moriya
Published: February 2005

Wetting studies of (Pb0.905, La0.095)(Zr0.65, Ti0.35)O3 with electrode metals were carried out under different atmospheres such as Ar, N2 and O2 (Ar-mixed O2, except for 100% O2). Wettability was evaluated by measuring the contact angle after wetting experiments. As a result, Cu was found to spread onto (Pb, La)(Zr, Ti)O3 in oxygen atmosphere, to more than 1.2%, and the contact angles of Ag and Sn on (Pb, La)(Zr, Ti)O3 decreased by about 10° in 100% oxygen atmosphere. The mechanism of wettability can be theoretically explained in terms of the potential change, taking into consideration the time of interaction at the interfaces between the metal and the oxide substrate.
Influence of Fringe Fields on Electrostatic Aharonov-Bohm Effects in Mesoscopic Ring
Authors: Kuniichi Ohta Kuniichi Ohta , Daisuke Takai Daisuke Takai
Published: February 2005

A new method is invented to treat electron transport in the Aharonov-Bohm (AB)-type ring geometry where transport in each branch of the ring can be treated separately in terms of transfer matrix theory. The influence of fringe field due to the potential edge on the AB effect in a mesoscopic ring is thereby formulated. In the case of potential with an abrupt step, it is found by numerical calculations that the standard treatment of AB effects is approximately permissible at a low enough electrostatic potential of practical interest. The phase of quantum oscillation, however, shifts towards low electrostatic potential, and the amplitudes slowly decay as a function of electrostatic potential as it becomes high. In the case of realistic potential with gradual steps, the transfer matrix can be written in an ordered product of infinitesimal matrices causing AB phase shift and electric-field-dependent amplitude modulation. It is shown that the validity of the usual AB treatment can be assessed in terms of the concept of adiabatic condition.
Microstructural Analysis of Interface Between YBa2Cu3O7-X and Ag/Pd Alloys
Authors: Ming-Hung Lo Ming-Hung Lo , Wen-Cheng Wei Wen-Cheng Wei
Published: February 2005

Pure silver and palladium/silver alloy in a 10/90 weight ratio were either sandwich-coupled or powder-mixed with YBa2Cu3O7-X
(Y123) to prepare Ag-Y123 and (Pd/Ag)-Y123 composites. The reaction and diffusion of elements near the interface of Ag-Y123 or (Pd/Ag)-Y123 were determined by means of differential thermogravimetry (DTA), optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and precision X-ray diffraction (XRD) analyses. The results reveal that the Pd, Ag, and Cu react to some extent: Cu will diffuse into pure Ag or Pd/Ag alloy. Conversely, Pd and Ag in pure Ag or Pd/Ag will diffuse toward Y123 at temperatures greater than 945°C. Diffusion of Cu into pure Ag or Pd/Ag alloy will decrease the melting point of the Ag or Pd/Ag alloy due to formation of a solid solution and/or an eutectic constitution. Since molten Cu/Ag or Cu/Pd/Ag alloys can flow across the interface by means of capillary force between Y123 grains, they fill up the voids (or capillaries) between Y123 grains and Ag or Pd diffuse into Y123 grains, occupying Cu sites in Y123. This is consistent with the results of precision XRD, which show the expansion of the Y123 lattice caused by the occupation.
Experimental Study of Nonlinear Dielectric Relaxation Spectra of Ferroelectric Liquid Crystals in the Smectic C* Phase
Authors: Yasuyuki Kimura Yasuyuki Kimura , Reinosuke Hayakawa Reinosuke Hayakawa
Published: February 2005

Nonlinear dielectric relaxation spectra of two kinds of ferroelectric liquid crystals (FLC) are investigated in the chiral smectic C (SmC*) phase. The linear spectrum shows the relaxation of Debye type and the third-order nonlinear spectrum also shows the relaxation of Debye type generalized to the nonlinear case. The third-order nonlinear dielectric increment is found to be negative, which indicates that the dielectric nonlinearity of FLCs in the SmC* phase mainly originates from the saturation of molecular dipole moments induced by the applied electric field. The profiles of linear and nonlinear spectra remain almost unchanged throughout the SmC* phase. In the vicinity of the SmA-SmC* phase transition temperature, the linear spectrum shows the critical behavior of Curie-Weiss type and the third-order spectrum shows a sharp peak.
Tristable Switching in SmO* of 1-Methylheptyl-Terephthalidene-Bis-Aminocinnamate (MHTAC) and Its Miscibility with SmCA
* of Antiferroelectric Chiral Smectic Liquid Crystal
Authors: Takanishi Yoichi , Takezoe Hideo , Johno Masahiro , Yui Tomoyuki , Atsuo Fukuda Atsuo Fukuda
Published: February 2005

We investigated the electrooptic property of the SmO* phase in 1-methylheptyl-terephthalidene-bis-aminocinnamate (MHTAC), and confirmed its antiferroelectric characteristics. We also studied the miscibility of the SmO* phase with the antiferroelectric SmCA
* phase, and found that the two phases are identical.
Quasi-Static and Dynamic Density Fluctuations in the Glassy State II. Temperature Dependences of the Density Fluctuations for Polymethylmethacrylate
Authors: Tomoyoshi Yamashita Tomoyoshi Yamashita , Kensuke Kamada Kensuke Kamada
Published: February 2005

The Vυ scattering profile of glass displays two characteristics in precise light-scattering measurements. One characteristic is of speckle patterns (Vυqst) due to frozen-in (quasi-static) density fluctuation. The other is background scattering (Vυdyn) observed beneath the speckle patterns, which is caused by the dynamic density fluctuation. Temperature dependences of Vυqst and Vυdyn were investigated at several temperatures ranging from room temperature to around T
g and the wavelength of 488 nm for polymethylmethacrylate (PMMA). As a result of this experiment, it has been verified for the first time that the increase of Vυ (≈Vυiso) with increasing temperatures is the result of an increase of Vυdyn, i.e., that the increase of Vυiso results from the increase of the dynamic density fluctuation much remaining in the glassy state. On the other hand, the Vυqst dose not significantly change from room temperature to approximately T
g, and above T
g, the Vυqst drastically decreases due to thawing of the frozen-in density fluctuation.
Mechanical Properties of Diamond Membranes
Authors: Yumi Aikawa Yumi Aikawa , Kazuhiro Baba Kazuhiro Baba
Published: February 2005

Polycrystalline diamond films were deposited using the hot-filament chemical vapor deposition method. The fracture strength for these membranes was estimated in a bulge test and from Young's modulus measurement. These mechanical properties are changed by the substrate pretreatment conditions, the methane concentration, and the dc bias application between filaments and substrate. The maximum fracture strength was achieved at 2200 MPa, when 700 mA dc bias current was applied. The main characteristics for this film are a small grain size (0.3 µm) with relatively low nondiamond carbon content. It is concluded that the mechanical properties for diamond film are greatly affected by both grain size and nondiamond content in the film.
Simultaneous Measurements of Energetic O- Ions and O Atoms in Sputtering of Zinc Oxide Target
Authors: Tominaga Kikuo , Sueyoshi Yasuhiko , Imai Hiroshi , Munfei Chong Munfei Chong , Yoshihiro Shintani Yoshihiro Shintani
Published: February 2005

Energetic negative ions and neutral atoms were observed simultaneously using a time-of-flight apparatus for conventional planar magnetron sputtering of a ZnO:Al target in Ar and O2 gases. Energetic ions such as O- and O2
- and energetic neutral O atoms were detected in time-of-flight spectra. The gas pressure dependence of signal intensities of the spectra were measured, and the behavior of the energetic particles was examined. The ratio of the secondary electron emission coefficients of O- ions and O atoms at the collector was estimated from the results, and the relative intensities of the fluxes of O- and O were estimated. The scattering mechanism of energetic O- ions with Ar gas and O2 gas is discussed.
Generalized Ohm's Law for Partially Ionized Plasmas with Gradient of Electrical Conductivity
Authors: Kayukawa Shun-ichi Oikawa
Published: February 2005

A turbulence model for the generalized Ohm's law in partially ionized
plasmas with the spatial gradient of electrical conductivity is proposed.
The present model suggests that when there is a spatial gradient of
electrical conductivity, ∇σ, on a plane perpendicular to the
magnetic field, fluctuating motions of partially ionized plasmas are
anisotropically suppressed, even on the perpendicular plane, due to the
anisotropic Lorentz force exerted on the plasma.
As a result, we insist that the application of a magnetic field perpendicular to ∇σ induces a steady mass flow directed to ∇σ,
which alters the mean profiles of the temperature and velocity fields.
It has also been shown that with increasing temperature fluctuations,
the effective conductivity in the present model decreases,
although the time-averaged conductivity increases because of the nonlinear
dependence of the conductivity on temperature.