bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the Crystallographic and Photoluminescent Properties of Cd3InGaS6. I. Crystallographic Study
Authors: Irie Taizo , Ando Shizutoshi , Noda Yasutoshi , Saburo Endo Saburo Endo
Published: February 2005

X-ray studies of Cd
x
InGaS3+x
(1.0≦x≦3.5) were carried out to clarify the crystallographic state of Cd3InGaS6 which was found to show very intense green photoluminescence at low temperatures. The X-ray diffraction pattern showed that Cd3InGaS6 is a mixture of CdS and CdInGaS4. Relative intensity of the diffraction line at 2θ=26.5° to two adjacent lines, where θ is the Bragg angle, indicates that CdS and CdInGaS4 are laminated in the direction of the c-axis of the hexagonal structure. A computer simulation of the diffraction pattern based on the laminated model was carried out and could nearly reproduce the experimental diffraction pattern. The X-ray diffraction from the growth face of the crystals and the Weissenberg photograph revealed the laminated structure.
Thermal Expansion Coefficient of Synthetic Diamond Single Crystal at Low Temperatures
Authors: Haruna Katsuji , Maeta Hiroshi , Kazutoshi Ohashi Kazutoshi Ohashi , Takuro Koike Takuro Koike
Published: February 2005

The lattice parameter of synthetic diamond single crystals has been measured in the range 4.2-320 K by the X-ray diffraction method. The lattice parameter is found to be nearly constant between 4.2 and 90 K. The thermal expansion coefficient α calculated from the experimental results is very small (of the order of 10-7 or less) and no definite evidence of the negative thermal expansion is found within our relative experimental accuracy of the order of ±1×10-6.
Fine Adjustment Based on Model for X-Ray Absorption Fine Structure of Ni-Fe Alloy
Authors: Yoshiaki Tanida Yoshiaki Tanida , Satoshi Komiya Satoshi Komiya
Published: February 2005

To increase the reliability of the structural parameters, the FABM has been applied to the best fit data obtained from two kinds of Ni-Fe films. The sputtered sample is closer to the crystalline Ni3Fe than the plated one, which becomes consistent with an interpretation of the X-ray diffraction data. This shows that the FABM is very useful for correcting the BFBT results.
Superstructures Induced by Ni Adsorption on a Clean Si(110) Surface Studied by Reflection High-Energy Electron Diffraction-Total Reflection Angle X-Ray Spectroscopy
Authors: Youiti Yamamoto Youiti Yamamoto
Published: February 2005

Detailed study using RHEED-TRAXS (reflection high-energy electron diffraction-total reflection angle X-ray spectroscopy) has shown that 4×5, 5×4, 1×2, 1×5, 1×7 and 1×9 structures were formed when Ni adhered to a clean Si(110) surface with (11, 5)×(2̄,2) structure. It also showed that reversible phase transitions took place among structures other than the 4×5 structure depending on the amount of Ni adsorption and the surface temperature. The atomic arrangements of Ni atoms of the 4×5 and 5×4 structures were deduced on the basis of the intensity analysis and RHEED-TRAXS results.
Calculation of Incident Angle Dependence of Ion-Induced Kinetic Electron Emission from Aluminum
Authors: Kawata Jun , Ohya Kaoru , Mori Ichiro
Published: February 2005

The Monte Carlo simulation of transport of incident ions and recoiling target atoms is combined with the semiempirical theory of ion-induced kinetic electron emission (KEE) for calculating the incident angle dependence of the KEE yields. The calculation was made for light and heavy ion impact on Al in the energy range from 100 eV to 1 MeV. The present results are consistent with the experimental data and have revealed the origin of the deviation from the inverse cosine law, which corresponds to the contributions from backscattering ions and recoiling target atoms.
A New Method for Measuring the Neutralization Factor in a Compact Electron Storage Ring
Authors: Takada Hiroshi , Tomimasu Yoshihiro Hirata
Published: February 2005

Response of trapped ions when a clearing voltage was turned off was observed with a charge coupled device (CCD), detecting the time variation of the synchrotron radiation (SR) intensity from the central density of electrons in the stored beam. This enabled us to estimate the neutralization factor and compare it to that obtained from measurements of the betatron tune shift. It is expected that this new method will contribute to the study of ion trapping.
Kinetic Simulation of the Transient Sheath in Plasma Ion Implantation
Authors: Sang June Hahn Sang June Hahn , Jae Koo Lee Jae Koo Lee
Published: February 2005

Kinetic particle simulation modeling of a system consisting of plasma, sheath, material, and an external driving circuit is carried out. Plasma ion implantation relies on ion acceleration in the sheath region to a necessary energy level (10-50 keV). The dynamic evolution of the sheath is highly nonlinear and complex, especially when the negative voltage applied to the target material is modulated at a finite frequency to contain the sheath expansion to a manageable size. Our approach uses a kinetic particle-in-cell (PIC) simulation method for a bounded plasma system allowing an external circuit, as in the laboratory experiment. It predicts the kinetic properties which cannot be determined by the fluid approach. When the effect of voltage ramping is considered, the fast dynamic behaviors of the transient sheath such as an initial blow-up of the sheath, can be clearly understood. Except for the very fast ramping, our results are consistent with those of analytic and fluid calculations. The collisional effect is significant, but the temperature effect is negligible.
Field Line Diversion Properties of Finite β-Helias Equilibria
Authors: Hayashi Takaya , Ulrich Schwenn Ulrich Schwenn , Erika Strumberger Erika Strumberger
Published: February 2005

The diversion properties of the magnetic field outside the last closed magnetic surface of a Helias stellarator configuration [Phys. Lett. A 114 (1986) 129; Phys. Lett. A 129 (1988) 113] are investigated for finite pressure equilibria. The results indicate that a divertor concept which has been developed from the diversion properties of the corresponding vacuum field can be maintained for finite pressure equilibria. Cross-field particle transport is simulated by a simplified scrape-off layer (SOL) model.
A Study of Layer Thickness and Interface Qualities of Strained InxGa1-xAs/GaAs Layers
Authors: Hsu Wei-Chou , Shou-Zen Chang Shou-Zen Chang , Wei Lin Wei Lin
Published: February 2005

The relationships between the layer thickness and the corresponding interface qualities of strained InGaAs/GaAs quantum wells grown by low-pressure metalorganic chemical vapor deposition are investigated. The strain-induced phenomena are explained from the transmission electron microscopy (XTEM) images and low-temperature photoluminescence (PL) measurement. When the critical layer thickness of InGaAs was approached, extrinsic luminescence in the PL emission spectra and an interface wavy effect in the XTEM image were observed. A new “3-dimensional confinement model” is proposed to explain these phenomena satisfactorily.
Focusing Properties of a Linear-Phase Bragg-Fresnel Lens
Authors: Aristov Vitali V. , Basov Yuri A. , Goureev Timour E. , Snigirev Anatoly A. , Ishikawa Tetsuya , Izumi Koichi , Kikuta Seishi
Published: February 2005

Hard X-ray focusing by a linear phase Bragg-Fresnel crystal lens was performed with an efficiency close to 30%. The phase shift of an incident beam was controlled by deviating the crystal lens from the exact Bragg condition. Analytical expressions for the intensity and the image contrast at the focal point was presented.
A High-Gain AlGaAs/GaAs Heterojunction Bipolar Transistor Grown on Silicon Substrate
Authors: William Liu William Liu , Sam-Dong Kim Sam-Dong Kim
Published: February 2005

High gain AlGaAs/GaAs heterojunction bipolar transistors (HBTs) grown on silicon substrate have been fabricated. These HBTs-on-Si incorporate depleted AlGaAs passivation ledge to reduce extrinsic base surface recombination current and base quasi-electric field to reduce base bulk recombination current. Measured current gain of 100 is obtained for devices with an emitter area of 4×10 µm2. To our knowledge, this is the highest current gain reported for AlGaAs/GaAs HBTs grown on Si substrates. The dominant base current components is determined. The leakage currents of the base-collector junctions are also examined, and are compared to similar devices grown on GaAs substrate. Implications of these observed junction characteristics of HBTs-on-Si for power applications are discussed.
Site Occupancies of Sr and Ca Ions in Bi2(Sr1-xCax)3Cu2Oy Studied by Photoemission Core-Level Spectroscopy
Authors: Tanaka Kazuhide , Hiromu Takaki Hiromu Takaki , Seiichi Mizuno Seiichi Mizuno
Published: February 2005

The range of Sr/Ca substitution for the formation of a superconducting 2212 phase in sintered Bi2(Sr1-x
Ca
x
)3Cu2O
y
has been examined by X-ray powder diffraction. It has been found that the 2212 monophase is formed in the range 1/3≤x≤0.6. X-ray photoelectron spectra (XPS) of Sr3d and Ca2p core levels of these samples can be decomposed into higher- and lower-binding-energy components. They are attributable to Sr and Ca ions occupying the cation sites of SrO and Ca layers of the 2212 phase. The interrelation between the two spectral components of each ion and the two kinds of occupation sites is examined, and the distribution probabilities of the Sr and Ca ions on these sites are evaluated.
Superconductivity and Electrical Resistivity in the T′-Phase Pr2-yLay-xCexCuO4-δ
Authors: Koike Yoji , Kakimoto Akihiro , Mochida Mitsunori , Sato Hidetaka , Noji Takashi , Masatsune Kato Masatsune Kato , Yoshitami Saito Yoshitami Saito
Published: February 2005

Effects of the La substitution for Pr on the superconductivity and the electrical resistivity have been investigated in Pr2-y
La
y-x
Ce
x
CuO4-δ of the T′-phase. For heavily La-substituted samples of 1.0≦y≦1.2, superconductivity of the bulk appears in the range of smaller x values, 0.10≦x\lesssim0.15. This is discussed in relation to the electrical resistivity and the carrier concentration in the CuO2 sheet.
Rotational Temperature, Inversion Density and Absolute Population Density for the CO2 (0002) Sequence Band Laser
Authors: Shimizu Fumiko O. , Fujisawa Tadahito , Yokoyama Yasuhisa , Takahashi Hiroki , Minoh Mariko Hara
Published: February 2005

Accurate values of the physical parameters such as rotational temperature, inversion density, absolute population density in the regular and (0002) sequence bands of the CO2 laser have been determined. Those parameters characterize the lasing processes and interference between both bands. The dependences of the parameters on the partial pressures of foreign gas and the effects of foreign gas are also examined. It is confirmed that the rotational temperature is always well defined in any vibrational state. However, they are not necessarily equal to each other and to the translational temperature.
Photoluminescence of Sb3+ Centers in SrS and SrSe
Authors: Yamashita Nobuhiko , Yoh-ichi Sasaki Yoh-ichi Sasaki , Kaizo Nakamura Kaizo Nakamura
Published: February 2005

Emission and excitation spectra and luminescence decay times of the SrS:Sb3+ and SrSe:Sb3+ powder phosphors are studied over the temperature range from 2 to 372 K. The emission band at 293 K is located at 600 nm for SrS:Sb2S3 (0.05 mol%) and at 633 nm for SrSe:Sb2S3 (0.2 mol%). The excitation processes are attributed to three transitions; (i) the intraionic transitions within Sb3+, (ii) the charge transfer transition from the host anion to Sb3+ and (iii) the fundamental absorption by host crystal, followed by the transfer of the excitation energy to an unexcited Sb3+ ion. The shape of the excitation spectrum of the intraionic transitions is similar to those of the absorption spectra of Tl+-type ions in alkali halides. The results are compared with those of MgS:Sb3+, CaS:Sb3+, CaSe:Sb3+ and SrS:Bi3+.
Optical Properties of Cd1-xMnxTe Epitaxial Films Deposited on Sapphire Substrates
Authors: Takashi Inukai Takashi Inukai , Ken'ichi Ono Ken'ichi Ono
Published: February 2005

Cd1-x
Mn
x
Te epitaxial thin films with a smooth surface and high crystal quality were prepared on sapphire substrates by vacuum evaporation, and their Faraday effect and optical properties were investigated. The peak-to-peak rotation in the Verdet constant spectrum is 1.5 deg/Oe cm near the 0.57 µm wavelength at the energy gap for films where x=0.5. The refractive index at a 0.63 µm wavelength is 2.8∼3.0 for the x=0∼0.68 composition range, and it decreases as the Mn content increases. The optical attenuation at 1.52 µm decreases as the crystal quality improves, and the minimum attenuation is 2 dB/cm. Films with different structures have different attenuations. The wavelength dependence of the attenuation obeys Rayleigh's law of scattering. It is thought from these results that the attenuation is due to scattering based on the structure of the films.
Main Peak Profiles of Total Reflection X-Ray Fluorescence Analysis of Si(001) Wafers Excited by Monochromatic X-Ray Beam W-Lβ (I)
Authors: Yakushiji Kenji , Ohkawa Shinji , Yoshinaga Atsushi , Harada Jimpei
Published: February 2005

It is shown that the main peak profiles of monochromatic Total reflection X-ray fluorescence analysis (TXRF) depend very much on the misorientation of the crystallographic [001] axis or the vicinal surface of Si(001) wafer from the crystallographic direction, when TXRF is used for trace analysis of Si wafers. This phenomenon is closely related to the diffraction phenomenon of evanescent beam penetration into a Si wafer under the condition of total external reflection.
Diagnostics of Plasma Performance in Magnetohydrodynamics Generators
Authors: Okinaka Noriyuki , Yatsu Shigeo , Yoshiaki Aoki Yoshiaki Aoki , Naoyuki Kayukawa Naoyuki Kayukawa
Published: February 2005

Average measurements of conductivities and Hall parameters in a Faraday-type magnetohydrodynamics (MHD) generator are presented. The measurement scheme is simple and requires no optical observations other than probes that provide two-dimensional voltage field measurements in the generator. No corrections are made for the conductivity profiles at the generator walls. The use of this scheme for the estimation of average flow velocities is described, and may provide a valuable tool to diagnose the generator performance in real time.
Reaction Mechanism of Chemical Vapor Deposition Using Tetraethylorthosilicate and Ozone at Atmospheric Pressure
Authors: Kawahara Takaaki , Akimasa Yuuki Akimasa Yuuki , Yasuji Matsui Yasuji Matsui
Published: February 2005

The decomposition process of tetraethylorthosilicate (TEOS) and ozone at atmospheric pressure was measured in a closed vessel by in-situ Fourier-transform infrared absorption (FT-IR) analysis, and the changes of the deposition rate and the overall sticking probability β of the film precursor were obtained along the flow direction in a flow-type reactor. It has been found that the film precursors are formed by TEOS decomposition with O-atoms and/or ozone in the gas phase, and that CH3CHO may be the first product, followed by the oxidation to CO2 and H2O via HCHO. It is also shown that the film quality changes along the flow direction, that is, O-H bonds in the film decrease and the β-value increases as the reaction proceeds. These results may show that there are several kinds of precursors, and the sticky (unstable) precursors become dominant in the later stages.
Preparation of PbTiO3 Thin Films by an Excimer Laser Ablation Technique with Second Laser Irradiation
Authors: Tabata Hitoshi , Murata Osamu , Kawai Tomoji , Kawai Shichio , Okuyama Masanori
Published: February 2005

Ferroelectric PbTiO3 thin films have been formed on based electrodes of Pt or oxide superconductor ((La, Sr)2CuO4) by an ArF excimer laser ablation technique. A second laser irradiation at the substrate surface is quite effective in the crystallization of the films at low substrate temperature below 400°C. The suitable energy density of the irradiation laser is in the range of 30-100 mJ/cm2. X-ray diffraction patterns of PbTiO3 thin films show c-axis orientation, with FWHM (full width at half maximum) of rocking curve of 0.5°-1.0°. These films exhibit a ferroelectric hysteresis loop. The dielectric constant and remanent polarization of the PbTiO3 films are in the range of 120-150 and 20-25 µC/cm2, respectively.
Preparation of PbTiO3 Thin Films by Reactive Ionized Cluster Beam Deposition
Authors: Hayamizu Shunichi , Akira Yahashi Akira Yahashi , Yoshitaka Shibata Yoshitaka Shibata
Published: February 2005

PbTiO3 thin films were prepared by reactive ionized cluster beam (R-ICB) deposition on highly (100)-oriented Pt films formed on SiO2/Si substrates. PbTiO3 thin films consisting of c-axis- and a-axis-oriented crystallines with perovskite structure were obtained at a comparatively low substrate temperature of 430°C. We think tensile stress exists in PbTiO3 thin films, and it may be the cause of a-axis orientation. It is considered that fabricating high-density PbTiO3 thin films by applying an acceleration voltage decreases the tensile stress in the film and is advantageous for preparation of c-axis-oriented PbTiO3 thin films.
Surface Acoustic Waves in High-TcSuperconducting Thin Films on Piezoelectric PbTiO3Films
Authors: Akinaga Masahiro , Fukuda Hideaki , Ohkubo Hiroshi , Fukami Takeshi , Aomine Takafumi
Published: February 2005

To generate surface acoustic waves (SAW) and to fabricate substrates for superconducting Bi-compound film, piezoelectric PbTiO3films with preferredc-axis orientation were prepared on MgO (100) substrates by the rf-sputtering method. By using an interdigital electrode fabricated on PbTiO3film for generation and detection of SAW, it has been confirmed that SAW with the frequency of 192 MHz are propagated on PbTiO3film/MgO substrate, as-deposited Bi-compound film/PbTiO3/MgO substrate and heat-treated superconducting Bi-compound film/PbTiO3/MgO substrate. The temperature dependence of the SAW attenuation coefficient has been investigated below room temperature in detail, especially in the neighborhood of the superconducting transition temperature, and found to exhibit almost monotonic decreasing behavior with decreasing temperature.
Effects of the Reaction Pressure on the Growth of PbTiO3 Thin Films by the Photo-Chemical Vapor Deposition Method
Authors: Ando Akira , Katayama Takuma , Shimizu Masaru , Shiosaki Tadashi
Published: February 2005

Growth of PbTiO3 thin films was carried out by the photo-chemical vapor deposition (photo-CVD) method and by varying the growth parameters of substrate temperature, reaction pressure and UV light irradiation. In order to clarify the effects of these parameters on the thin film growth, a three-way-lay-out factorial experiment was done. In the higher temperature and pressure region the vapor phase reaction is dominant. At lower temperatures and pressures, the reaction on the substrate becomes significant. These tendencies were observed under conditions with and without UV light irradiation. The synthesis of PbTiO3 on Pt/sapphire was assisted by UV light irradiation.
Growth of Pb(Zr, Ti)O3 Thin Films by Photoenhanced Chemical Vapor Deposition and Their Properties
Authors: Katayama Takuma , Sugiyama Masataka , Masaru Shimizu Masaru Shimizu , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

Pb(Zr, Ti)O3 thin films were grown by photoenhanced chemical vapor deposition (CVD) using Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4 and O2. Two types of perovskite Pb(Zr, Ti)O3 films (tetragonal films and rhombohedral films) were successfully obtained at 600-635°C by controlling the carrier flow ratio of the Zr source to Ti source. The Zr/Ti flow ratio also affected the growth rate, composition and electrical properties of films. In this study, it was proven that significant increases in both growth rate and Zr/Ti compositional ratio were caused by photoirradiation. Dielectric and ferroelectric properties, switching characteristics and I-V characteristics of the obtained Pb(Zr, Ti)O3 films were also described in detail.
Piezoelectric Characteristics of ZnO Films Deposited Using an Electron Cyclotron Resonance Sputtering System
Authors: Kadota Michio , Minakata Toru Kasanami
Published: February 2005

Piezoelectric properties of ZnO films were investigated for the first time by means of an electron cyclotron resonance (ECR) sputtering system. It is confirmed that this system is capable of depositing a ZnO film with a large specific resistance, a good piezoelectric property and good c-axis orientation on an interdigital transducer (IDT)/glass substrate at a low temperature (less than 200°C) and under low gas pressure (∼10-4 Torr). These ZnO films exhibited excellent surface acoustic wave (SAW) characteristics (insertion losses) and effective electromechanical coupling factors (k
eff) compared with ZnO films deposited by a conventional RF magnetron sputtering system. Furthermore this ECR sputtering system was capable of depositing a ZnO film capable of driving a Rayleigh SAW of 700 MHz, without heating the substrate (room temperature), while it was impossible to drive such a wave conventionally, using other sputtering systems.
Electric Properties of SrTiO3 Thin Films Prepared by RF Sputtering
Authors: Kuroiwa Takeharu , Honda Toshihisa , Hisao Watarai Hisao Watarai , Ken Sato Ken Sato
Published: February 2005

Dielectric SrTiO3 thin films have been prepared on Pt/SiO2/Si-wafer by means of a conventional rf-magnetron sputtering technique. Electric and dielectric properties of the films have been studied. It is demonstrated that the leakage current of the films is strongly dependent on the atmosphere during deposition. The SrTiO3 film 75 nm in thickness fabricated in pure O2 of 26.6 Pa at 600°C obtained the lowest leakage current density of 4.0×10-9 A/cm2 at 2 V. Analysis of the leakage current vs applied voltage characteristic indicated that the conduction in the higher electric field was due to the Pool-Frenkel emission.
Microstructure and Piezoelectric Properties of Modified PbTiO3 Ceramics
Authors: Noboru Ichinose Noboru Ichinose , Masahiko Kimura Masahiko Kimura
Published: February 2005

This paper describes the effect of microstructure on dielectric and piezoelectric properties in the (Pb1-x
Ca
x
)[(Co1/2W1/2)0.04Ti0.96]O3 system. It is demonstrated that they are influenced by the microstructure, especially the grain size of the sintered bodies. The data of piezoelectric constants are compared with those of the values calculated using the theoretical model.
Sintering of Piezoelectric Ceramics with CO2 Laser
Authors: Sunao Sugihara Sunao Sugihara
Published: February 2005

Sintering of Pb(Zr0.53Ti0.47)O3 with a CO2 laser is discussed to indicate the possibility of a new method of synthesizing piezoelectric ceramics. The starting materials are (1) PbO, ZrO2 and TiO2, and (2) Pb3O4, ZrO2 and TiO2. The green oxide pellets are irradiated with a CO2 laser at various powers of 143, 286 and 1857 W/cm2 in a flow rate of 350 cm3/min of O2/Ar(105 Pa). In both cases, the formations of Pb(Zr, Ti)O3 were recognized by XRD (X-ray diffraction) analysis although some starting materials remained at the lower power. The microstructures are also discussed.
Ultrasonic Motors Using Longitudinal and Bending Multimode Vibrators with Mode Coupling by Externally Additional Asymmetry or Internal Nonlinearity
Authors: Aoyagi Manabu , Takano Yoshiro Tomikawa
Published: February 2005

The present paper deals with some ultrasonic motors using longitudinal and bending multimode vibrators with their mode couplings caused by externally additional asymmetry or internal nonlinearity. A rectangular plate vibrator with two corners on one diagonal line cut to make its resonance modes couple with each other was used, along with a rectangular plate vibrator under the condition that two resonance frequencies are obtained, for example, as f
L/f
B=2.0, because internal nonlinear coupling of parametric vibration between two resonance modes is generated under this condition. Using these vibrators with mode couplings, it was found that some ultrasonic motors of simple form can be constructed. The ultrasonic motor using the phenomenon of mode-coupling vibrations dealt with here is not completely new, and a few trial constructions have already been reported [Jpn. J. Appl. Phys. 24 (1985) Suppl. 24-2, p. 739]. However, their motions were not reversible in ordinary driving with an electrical signal of a constant frequency. In contrast, the motors that the authors proposed in this paper can be expected to have a reversible motion.
Contribution of Dielectric Constant to Change in Temperature Coefficient of Resonant Frequency in (Ba1-xSrx)(Mg1/3Ta2/3)O3 Compounds
Authors: Nagai Toru , Takayuki Inuzuka Takayuki Inuzuka , Masaaki Sugiyama Masaaki Sugiyama
Published: February 2005

Dielectric resonator materials with the formula (Ba1-x
Sr
x
)(Mg1/3Ta2/3)O3 have been studied in order to clarify the factors controlling the resonant frequency as a function of temperature. Dielectric constant and thermal expansion are calculated from the resonant frequency measured by the dielectric resonator method and the capacitance obtained at 10 kHz. The results show that the temperature dependence of the resonant frequency originates mainly from the change in the dielectric constant with temperature. The dielectric constant exhibits a maximum at some critical temperature, which varies with increasing strontium content in the oxides.
Second Harmonic Generation in Nb2O5 Thin-Film Optical Waveguide Deposited on LiTaO3 Substrate by RF Magnetron Sputtering
Authors: Shiosaki Yasuyoshi Saito
Published: February 2005

The first experimental observation of Cerenkov-type second harmonic generation (SHG) in an amorphous Nb2O5 thin-film optical waveguide on (0001) LiTaO3 substrate is reported. The Nb2O5 thin films were deposited by rf magnetron sputtering on LiTaO3 substrate. A Nd:YAG laser at 1064 nm wavelength was used as the pumping source for the SHG experiments. The conversions occurred between the fundamental (1064 nm) TE0 guided mode and the harmonic (532 nm) TM radiation mode, and between the TM0 guided mode and the TM radiation mode. The efficiency of both conversions was about 10-8 for a sample with a film thickness of 788 nm. These SHG results were in good agreement with the coupled-mode theory, and the theoretical calculation revealed that the low conversion efficiencies were due to the unsuitable film thickness. It was predicted that the efficiencies could be raised to a much higher level.
Field-Induced Phase Transition in an Antiferroelectric Liquid Crystal
Authors: Hayashi Hitoshi , Takemura Makoto , Kikuchi Katsuhide , Hijikata Yoshimasa , Orihara Hiroshi , Ishibashi Yoshihiro
Published: February 2005

Field-induced antiferroelectric-ferroelectric phase transition in an antiferroelectric liquid crystal 4-(1-trifluoromethylheptyloxycarbonyl)phenyl-4'-octyloxybiphenyl-4-carboxylate (TFMHPOBC) was studied by means of microscopic observation during the switching process and the measurement of the T-E hysteresis loops. It was clarified that the threshold voltage of the switching from the antiferroelectric state to the ferroelectric state and the transmittance at the threshold voltage depend on temperature, frequency and optical purity. The optical purity is an important factor for improving the contrast of display devices.
Lead-Lanthanum Zirconate-Titanate (PLZT) Electrooptic Variable Focal-Length Lens with Stripe Electrodes
Authors: Takashi Shibaguchi Takashi Shibaguchi , Hiroyoshi Funato Hiroyoshi Funato
Published: February 2005

This paper proposes new types of one and two-dimensional electrooptic (E-O) lenses of simple structure. The two-dimensional lens is composed of two one-dimensional E-O lenses which are arranged to converge light beams perpendicular to each other. The refractive index distribution of the lens is calculated using the finite-element method, and ray tracing is performed by solving the ray equation for each one-dimensional lens. Parameters of the E-O lens, such as electrode width and gap, and crystal thickness, are optimized. One and two-dimensional lenses are demonstrated, and the focusing and temporal characteristics are studied experimentally.
Properties of Electrooptic (Pb, La)(Zr, Ti)O3 Ceramics Fabricated by Partial Coprecipitation Method
Authors: Furuno Kunihiro Nagata
Published: February 2005

Electrooptic ceramics of (Pb, La)(Zr, Ti)O3 were fabricated by a combination of the partial-coprecipitation and doctor-blade methods. The PLZT powder, with particles of submicron size that were excellently dispersed, was prepared by (Zr, Ti)O2 solid-solution powder and PbO and La2O3 oxide powders. The large-scale PLZT ceramics with the dimension of 10×10∼20 cm and thickness of 1.5 mm were molded by the doctor-blade method and then conventionally sintered at 1200∼1250°C for 20∼60 h under the controlled condition of PbO and oxygen atmosphere. The fabricated PLZT ceramics with 0.5 mm thickness showed the transmittance of 65∼67% in the range of wavelength greater than 600 nm, and the quadratic electrooptical coefficient of 4.5×10-16 O2/V2.
Simulations of Polarization Reversals by a Two-Dimensional Lattice Model
Authors: Omura Masayoshi , Ishibashi Hideo Adachi
Published: February 2005

Simulations of step-type and pulse responses have been performed using a two-dimensional lattice model in ferroelectrics in which latent nuclei are randomly distributed. Polarization and current responses under the step-type applied field and the narrow applied pulse field shorter than switching time t
sw are described. The critical pulse width t
*, for which the system returns to the initial polarization state after the narrow applied pulse field is removed, is obtained, and it is found that the value of t
* depends on the applied field and the interaction between neighboring dipole moments.
Continuity in Phase Transition Behavior between Normal and Diffuse Phase Transitions in Complex Perovskite Compounds
Authors: Kuwabara Makoto , Takahashi Seiji , Goda Koji , Kenji Oshima Kenji Oshima , Koichiro Watanabe Koichiro Watanabe
Published: February 2005

The phase transition behavior in the systems of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) and 0.99Pb1-y
La2y/3TiO3-0.01MnO2 (PLT) relaxor ferroelectrics has been investigated to explore the nature of diffused phase transitions (DPT) in these materials. All the dielectric constant (ε)-temperature (T) characteristics for these materials above the Curie point have been found to be described by the equation (1/ε-1/εm)1/n
=(T-T
m)/C
′, where εm is the maximum dielectric constant of a material, T
m is the temperature giving εm, and n and C
′ are constants changing with composition. In the system PMN-PT, the value of n was found to change continuously from 1.0 for PT to 2.0 for PMN without any irregularity. The value of n for the materials of the system PLT also shows a similar variation with La content, and moreover, two C
′ versus T
m plots obtained for the two systems PMN-PT and PLT show substantially the same behavior. The nature of DPT is considered to be closely connected with compositional and structural variations, which determine the spatial size and morphology of ferroelectric domains below the Curie point.
Preparation of Ferroelectric Relaxor Pb(Zn1/2Nb2/3)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 by Two-Step Calcination Method
Authors: Orita Masahiro , Satoh Hironobu , Kazuhiro Aizawa Kazuhiro Aizawa , Kohei Ametani Kohei Ametani
Published: February 2005

Powder materials having the composition Pb0.88Ba0.12(Zn1/3Nb2/3)0.30(Mg1/3Nb2/3)0.50Ti0.20O3 were prepared by a two-step calcination method. All the constituent oxides, except for PbO, were precalcined, and then the resulting mixtures were postcalcined with PbO to obtain powders having the desired composition. A series of experimental studies of the powder and the ceramic showed that samples fabricated by the present method had better properties in terms of perovskite phase purity, sinterability, breakdown voltage and dielectric constant, compared to those prepared by the conventional method using one-step calcination.
Measurement Accuracy of Complex Permittivity in the Dielectric Rod Resonator Method
Authors: Takagi Hitoshi , Fujinami Naokatsu , Hiroshi Tamura Hiroshi Tamura , Kikuo Wakino Kikuo Wakino
Published: February 2005

The measurement accuracy of complex permittivity in the dielectric rod resonator method has been investigated. The measurement error of relative permittivity is 0.05% (standard deviation), which is permissible for the applications of resonators. The dielectric loss was measured by setting conducting plates at both ends of the dielectric resonator. The frequency dependence of the conductivity due to the surface roughness of the plates was investigated using three kinds of standard rod resonators. It is concluded that the measurement error of tan δ can be reduced to 1.5×10-6 (standard deviation) for a dielectric specimen with εr=30.2 at 10 GHz by using the high-Q standard dielectric rod resonators which are placed between conducting plates with surface roughness less than the skin depth at the measurement frequency.
Optical Measurement of Piezoelectric Vibration in Circular Rod and Disk Ceramics
Authors: Ohki Michio , Naomi Shima Naomi Shima , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

The fiber-optic measurement and evaluation of piezoelectric vibration of circular rod and disk ceramics are described. The values corresponding to the piezoelectric d- and g-constants can be obtained locally by measuring amplitude and Q-value at the first-resonance frequency under appropriate electric conditions. The results are analyzed numerically by using the theory of coupled resonance.
Characterization of GaAs/Si/GaAs Heterostructures
Authors: Rao T. Sudersena , Horikoshi Yoshiji , Jagadish C. , Elliman R. G. , Williams J. S.
Published: February 2005

GaAs/Si(n)/GaAs, n=1 to 3 mono-layers (ML) were grown on GaAs (100) substrates using molecular beam epitaxy. Double crystal X-ray diffraction rocking curve and Rutherford backscattering/chanelling studies indicated that 1 ML of Si grows coherently and psuedomorphicatly on GaAs and 2 and 3 ML Si exhibit increasing defect nature and are probably relaxed. Raman scattering measurements of the cap GaAs layer showed an increase in intensity of forbidden transverse optical (TO) phonon peak with increasing underlying Si layer thickness. Cross-sectional transmission electron microscopy studies revealed that for 1 ML Si, the Si-GaAs interface and the Si layer are defect free. However, for increasing thickness of Si to n=2 and 3 ML, defect density increased at the Si-GaAs cap layer interface.
Interface Recombination Reduction by (NH4)2Sx-Passivation in Metalorganic Chemical Vapor Deposition Regrown GaAlAs/GaAs Buried Heterostructure Lasers and Estimation of Threshold Currents in Microcavity Surface Emitting Lasers
Authors: Tamanuki Takemasa , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga
Published: February 2005

Ammonium sulfide [(NH4)2S
x
] treatment has been applied to a metalorganic chemical vapor deposition (MOCVD) regrowth process for GaAlAs/GaAs buried heterostructure (BH) lasers to reduce the nonradiative interface recombination. A mirrorlike Ga0.9Al0.1As layer was successfully grown on Ga0.7Al0.3As by introducing sulfur treatment before regrowth. The interface recombination velocity along the side wall of the active region was significantly reduced. This fabrication technology is expected to be effective in the realization of ultralow-threshold microcavity lasers.
Hysteresis Loops of Modulated Microwave Absorption and Flux Distribution in Granular Y1Ba2Cu3Ox
Authors: Tamio Endo Tamio Endo , Takashi Wada Takashi Wada
Published: February 2005

The hysteresis measurements of the modulated microwave absorption (MA) and the magnetization were made on granular Y1Ba2Cu3Oxas a function of the magnetic field (Ha) at 77 K. The intergrain critical state (CS) is established at ∼5 G, and it is virtually maintained to over 4 kG, and the inverse intergrain CS is maintained to below ∼200 G. The transition widths of the hysteresis loop of the modulated MA increase with increasingHawith smaller rate forHa<1700 G and larger rate forHa>1700 G. This indicates that the depth and the height of the intergrain critical states for the upward and the downward field sweeps increase. The height increases atHa>1700 G is maintained to the very low field of 50 G. The origin of these behaviors is discussed in terms of the corrective pinning of intergrain and intragrain vortex glass.
Microstructure and Critical Current Density of YBa2Cu3O7-x-Ag Composites Compressed at High Temperature
Authors: Kang Whang-Jin , Hanada Shuji , Yoshii Isamu , Nagata Akihiko
Published: February 2005

Microstructures of YBa2Cu3O7-x
-Ag composites compressed at high temperatures have been investigated, and relationship between the microstructures and superconducting properties is discussed. YBa2Cu3O7-x
specimens doped with 20 and 30 w/o Ag2O were well compressed to 55% plastic strain under a low stress level compared to the Ag2O-undoped sample. No microcracks were observed in the central zone of the composites reoxidized at 773 K for 18 h after compression at 1203 K and at 1.3×10-5/s. From this result, it is suggested that uniformly distributed Ag particles play an important role not only in ductile deformation at high temperatures but also in relieving the anisotropic stresses induced by phase transition and reoxidizing heat treatment. The maximum J
c(trans) value of 1400 A/cm2 at 77 K and 0 T was obtained in 20 w/o Ag2O-doped composites. The agglomerations of Ag particles, which were formed during compression of the 30 w/o Ag2O-doped sample, reduced the path of the current flows and eventually decreased J
c(trans).
Microstructures of Pt/Co Films Deposited on Sputter-Etched Underlayers
Authors: Sumi Satoshi , Tanase Kenji , Teragaki Yasuko , Torazawa Kenji , Tsunashima Shigeru , Uchiyama Susumu
Published: February 2005

Pt/Co multilayered films deposited on a sputter-etched SiN underlayer show larger magnetic anisotropy (1×106 erg/cm3) and better squareness(=1) than those on nonetched underlayers. The results of small-angle X-ray diffraction indicate the improvement of the multilayer structural order due to the etching. According to the transmission electron microscopy observation and the electrical resistivity measurement, the etching of underlayers transforms the Pt/Co films from island structure to continuous structure in an early stage of film growth. The scanning tunneling microscopy observation suggests that the sputter etching flattens the surface of the underlayer.
Calcium Fluoride Films Assisting Diffusion Bonding of MgF2 Ceramics
Authors: Tsung-Fu Yen Tsung-Fu Yen , Yen-Hwei Chang Yen-Hwei Chang
Published: February 2005

The bonding of magnesium fluorides by hot pressing was studied. A layer of CaF2 with 2∼3 µm thickness was used as an agent to decrease the bonding temperature and avoid breaching. The main factors that influence the light scattering loss were the cellular growth of MgF2 films, voids caused by the lattice mismatch due to the interfaces of each layer, voids due to the films, grain growth, and recrystallization zone formation. By contrast, the grain growth of the MgF2 matrix and CaF2 films was not the main influence on the scattering loss. Another important factor that influences the scattering loss was the refractive index variations, which are dependent on the composition fluctuations. Measurements of the discontinuities in the concentration-distance profile describing interdiffusion of the components in the binary systems CaF2-MgF2 gave the crystalline solubility limits just below the eutectic temperature and under the 430 kg/cm2 pressure. These are 17 at.% Ca in MgF2 at 650°C, 5 h, and discontinuous values over the recrystallization zone at 700°C, 5 h.
Photoluminescence on Li-Codoped ZnS:Tm Phosphor
Authors: Hatayama Tomoaki , Shigeru Fukumoto Shigeru Fukumoto , Sumiaki Ibuki Sumiaki Ibuki
Published: February 2005

Very strong sharp lines in luminescence of Tm3+ have been observed in Li-codoped ZnS:Tm phosphor. In particular, blue emission intensity was stronger as compared with that of infrared emission when the codoped Li concentration in ZnS:Tm was 0.1 at.%. As ZnS:Tm emits a broad band and very weak Tm3+ lines, the role of Li is proposed as follows: Li ions fill defects in the ZnS host, and hence excitation energy transfers from the ZnS host to Tm3+ very easily.
Characterizations and Barrier Properties of WNx Film in the Al12W/WNx/Si Contact System
Authors: Takeyama Mayumi , Katsutaka Sasaki Katsutaka Sasaki , Atsushi Noya Atsushi Noya
Published: February 2005

Characterizations and barrier properties of WN
x
film with varying nitrogen content have been examined in order to use the Al12W/WN
x
bilayer as a diffusion barrier in the contact system of Al/Si. The barrier properties of WN
x
film are evaluated from the viewpoint of the mass transport across the interfaces in the system of Al12W/WN
x
/Si, by comparing the depth profiles obtained from Auger electron spectroscopy (AES) analysis before and after the heat treatments at various temperatures. It is revealed from the comparison of depth profiles that thermal stabilities of the system are excellent up to 600°C, when the stoichiometric W2N compound film is used as the underlayer of the Al12W/WN
x
bilayer film.
Surface Electromigration and Diffusion of Ag on Ge(111)
Authors: Hitoshi Yasunaga Hitoshi Yasunaga , Tatsuhiro Aida Tatsuhiro Aida
Published: February 2005

Spread of a deposited Ag patch with coverage of several monolayers over Ge(111)-c(2×8) was observed with scanning Auger electron spectroscopy when the Ge substrate was heated by DC current. The spread-out Ag layer was uniform in coverage (1.0 monolayer) and structure (√3×√3-R30°) with a sharp leading edge. The longitudinal spread parallel to the current, dominated by the electromigration, was preferential towards the cathode with linear proportionality to the time of the DC power supply, while the transverse spread was well balanced and proportional to the square root of the time, consistently with the surface diffusion. The transverse spread exhibited a temperature dependence with the thermal activation energy of 0.50±0.1 eV. Theoretical expressions for the spreads were derived and compared with the data. The effective charge of the Ag adatom was as large as +(13±2)q.
Preparation of c-Axis Oriented AlN Thin Films by Low-Temperature Reactive Sputtering
Authors: Okano Hiroshi , Takahashi Yusuke , Tanaka Toshiharu , Kenichi Shibata Kenichi Shibata , Shoichi Nakano Shoichi Nakano
Published: February 2005

C-axis oriented aluminum nitride (AlN) thin films on (110) silicon were prepared by reactive RF magnetron sputtering in argon and nitrogen atmosphere without substrate heating. We investigated the dependence of some properties for the AlN thin film on sputtering conditions, especially N2 concentration. It was found that c-axis orientation tended to improve gradually with decreasing N2 concentration. The full width of half the maximum intensity (FWHM) of the rocking curve for a (002) plane of hexagonal AlN was 1∼2 degrees at a 10% N2 concentration. This was a suitable value for surface acoustic wave (SAW) device. IDT/AlN/(110)Si structure SAW resonators were fabricated. It was confirmed that the insertion loss was 14 dB and phase velocity was 4800 m/s, respectively.
Perceptron Circuit Using Lead Phthalocyanine Films
Authors: Nichogi Katsuhiro , Akira Taomoto Akira Taomoto , Kunio Yoshida Kunio Yoshida
Published: February 2005

Evaporated films of lead phthalocyanine exhibit a unique conductivity change via applied DC voltage. The change depends on the polarity and the strength of the input voltage and has a memory effect. The change is also observed when pulsed voltage is applied. In such a case, the change is multiplied by the input pulse itself because of the memory effect. Therefore, the change can be regarded as synaptic plasticity. Using the lead phthalocyanine films as synaptic connections, we constructed a perceptron circuit, which is one of the artificial neural networks, and demonstrated that the circuit can classify input patterns.
High-Resolution Hadamard Transform Spectrometer Using a High-Precision Encoding Mask
Authors: Horiba Ryuichiro , Fujisawa Shunzo , Yukiko Okazaki Yukiko Okazaki , Keigo Nagasaka Keigo Nagasaka
Published: February 2005

We have carried out an experiment to obtain limited resolving power using a high-precision Hadamard mask and a commercially available half-meter diffraction grating spectrometer, which has a diffraction grating with the blaze wavelength of 2 µm and total groove number of 15600. A 2×255-slot encoding Hadamard mask (total number of slots: 510) was prepared. The size of the 255-slot encoding mask was 5.18×5.00 mm2 and the width of one slot was 20.32 µm. With this system, mercury emission lines were observed in the wavelength range of 1.685 to 1.715 µm. The resolving power was determined by the experiment to be larger than 6560, while the theoretical value was about 13000.
Hybrid-Excitation Chemical Vapor Deposition of Silicon Nitride on (100)Si –The Film and Interface Properties-
Authors: Shigeichi Yamamoto Shigeichi Yamamoto , Masatoshi Migitaka Masatoshi Migitaka
Published: February 2005

Silicon nitride (SiN
x
) films are deposited on (100)Si substrates using silane (SiH4) and ammonia (NH3) gases by a hybrid-excitation chemical vapor deposition (hybrid-CVD) method at 280°C. In the deposition, the NH3 gas is decomposed by a radio frequency (13.56 MHz) discharge plasma, and is irradiated by 184.9-nm and 253.7-nm ultraviolet rays with SiH4 gas. The depositions are performed with emphasis on the gas flow ratio, NH3/SiH4, ranging from 3.3 to 29. The effective trapped carrier density at the interface between the SiN
x
film and the (100)Si substrate is reduced to 2.5×1010 cm-2 by the hybrid-CVD. The films show, moreover, high electrical resistance (e.g. 7×1015 Ω cm). These properties are better than those of the conventional plasma-enhanced CVD and photo-enhanced CVD films. The improvement mechanism in the bulk and interface properties is discussed.
Influence of Substrate Orientation on Be Transport during Molecular Beam Epitaxy of AlGaAs/GaAs Heterojunction Bipolar Transistors
Authors: Mochizuki Kazuhiro , Goto Shigeo , Tomoyoshi Mishima Tomoyoshi Mishima , Chuushiro Kusano Chuushiro Kusano
Published: February 2005

The influence of substrate orientation on Be transport during GaAs molecular beam epitaxy is evaluated by secondary ion mass spectrometry and from the current-voltage characteristics of AlGaAs/GaAs heterojunction bipolar transistors (HBTs). The Be doping level employed is from 2×1019 cm-3 to 9×1019 cm-3. The Be transport for the conventional (100) orientation increases rapidly with the increase of growth temperature (T
s) from 530°C to 630°C. With substrate misorientation from (100) toward (111)A, however, Be transport is decreased at T
s=630°C, and reaches a minimum with (311)A orientation. The maximum current gain of AlGaAs/GaAs HBTs grown at T
s=560°C is 264 for (411)A orientation and 3 for (100) orientation, which confirms the applicability of substrate orientations other than the conventional (100) one for obtaining a sharp Be profile.
Analysis of Effective Channel Length in Amorphous Silicon Thin-Film Transistors
Authors: Kaneko Yoshiyuki , Tooru Toyabe Tooru Toyabe , Toshihisa Tsukada Toshihisa Tsukada
Published: February 2005

This paper analyzes the effective channel length in amorphous silicon thin-film transistors (a-Si TFTs) by examining the parasitic channel length, ΔL, which causes the apparent dependence of the field-effect mobility of TFTs on the nominal channel length. The parasitic channel length is found to depend on the a-Si thickness, L
a, at the source path and the drain path of TFTs if there is no etching stopper insulator on the a-Si layer. An analytical formula for the parasitic channel length is derived by assuming that the space-charge-limited current is the dominant conduction mechanism through these paths. The validity of the analysis is confirmed by applying the formula to the experimental results on the ΔL-L
a relationship for a range of L
a between 0.18 and 0.98 µm.