bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR Study of Y2Co14Bx Compounds
Authors: Maruyama Fumio , Nagai Hiroyuki , Amako Yasushi , Yoshie Hiroshi , Adachi Kengo
Published: October 2002

In order to study the contribution of B atoms to the magnetic properties of Y2Co14B

x

with 0.75≤x≤1, the 59Co NMR and magnetic measurements were carried out at 4.2 K and 77 K, respectively. The saturation magnetization, M
s, increased with B content and the value of ΔM
s was 1.1 µ B/ f.u. for 0.75≤x≤1. The 59Co hyperfine fields, H
hf( Co), at 16k
1 and 4e sites increased and those at 16k
2 and 8j
1 sites decreased with B content. The increase and the decrease in H
hf( Co) were caused by the decrease and the increase in the Co orbital moment, respectively.
Increased Optical Damage Resistance and Transparency in MgO-Doped LiTaO3 Single Crystals
Authors: Nitanda Fumio , Furukawa Yasunori , Makio Satoshi , Sato Masayoshi , Kohei Ito Kohei Ito
Published: October 2002

Clear and transparent 2-inch diameter undoped and MgO-doped LiTaO3 single crystals with few Fe impurities have been grown by the conventional Czochralski method from a congruent melt. The optical damage resistance of undoped LiTaO3 has been characterized by the measurement of photoinduced birefringence change and is lower than that of commercially available LiNbO3, which is not consistent with the previously reported data in the literature. In addition, doping of a few mol% MgO further improved the optical damage resistance, transmission in the visible light region, and crystal decolorization, and produced a favorable shift of absorption edge toward shorter wavelengths for lithium tantalate. These are important advantages when considering shorter- wavelength accessibility and high conversion efficiency in second-harmonic- generation devices.
Accelerated Response of Photochromic Liquid Crystalline Cell by Laser Pulse Excitation
Authors: Kamezaki Hisamitsu , Kawanishi Yuji , Ichimura Kunihiro
Published: October 2002

Alignment relaxation of a photoresponsive liquid crystalline (LC) cell, in which a nematic phase is sandwiched between a pair of azobenzene (Az)-modified quartz plates, was measured by means of laser pulse excitation. The relaxation constant τ of the alignment change from the perpendicular state to the parallel state along the photoisomerization of Az showed wide variation between 1000 ms and 10 ms depending on the number of injected pulses and their intensity. The dependence of τ below 20 mJ/cm2 excitation was consistent with the change in the photoisomerization yield of Az. Above this power, τ still showed moderate reduction although the photoisomerization yield approached a saturated value, indicating the presence of a secondary factor.
Imaging in an Optical Projection System with a Laser Light Source. I: Gaussian Laser Light Illumination
Authors: Takamoto Kiichi , Yoshio Kawai Yoshio Kawai
Published: October 2002

Intensity distributions for a line-and-space pattern with 5 lines are calculated using a one-dimensional model. Their dependence on Gaussian laser light illumination is analyzed. The laser light travels distance z and illuminates a second light source plane for an illumination system. The complex coherence factor µ12 at the object plane has an absolute value of 1, but a change in the phase of µ12 becomes greater with increasing distance z or coherence factor σ c. Compared with imaging in incoherent light source systems, intensity distributions at the image plane are more easily varied depending on z and σ c, and focal tolerance is narrower.
Imaging in an Optical Projection System with a Light Source Composed of Point Sources
Authors: Takamoto Kiichi
Published: October 2002

The effects of a points source on imaging characteristics are examined using a one-dimensional model. Intensity distributions for a line-and-space pattern with 5 lines are calculated and the imaging characteristics are evaluated, compared with those obtained using a plane-source system. In a system with a light source composed of 2 point-sources, the focal tolerance determined from linewidth and contrast becomes maximum. Using a light source composed of 3 point-sources, the line-and-space pattern is imaged with precise linewidths while maintaining a focal tolerance slightly larger than that for the plane-source system.
Investigation of the Characteristics of a Piezoelectric Chopper for a Modulation-Type Pyroelectric Infrared Detector
Authors: Takeuchi Kousuke , Yokoo Toshiaki , Tanaka Toshiharu , Shibata Kenichi , Shoichi Nakano Shoichi Nakano
Published: October 2002

The characteristics of a piezoelectric chopper utilizing a slit plate for a modulation-type pyroelectric infrared detector (M-type IR detector) were investigated. First, we discuss how the accuracy of the signal of the M-type IR detector is affected by the emissivity of the slit plate, for applications to noncontact temperature measurement. Then, the accuracy of the measurement can be improved by an optimum emissivity of the slit plate against changes in operating gate-source voltage of the field-effect transistor, when the ambient temperature of the detector is changed rapidly. Next, we study the change in the detecting area caused by the diffraction effect from the use of the slit plate by means of numerical simulation and experiments. The expansion of the detecting area due to the diffraction can be improved by an optimum design of the can structure.
Effect of Ferrite Magnetic Wedge on Characteristics of Capacitor Motor under Asymmetrical Voltage Application
Authors: Kaga Akio , Tajima Katsubumi , Itoh Tadahito , Norihiko Yohkawa Norihiko Yohkawa
Published: October 2002

The characteristics of the capacitor motor under voltage control are highly applicable to home electric appliances. In this study, the supply voltage controlled by a triac has been applied to a split-phase capacitor motor. The capacitor motor usually produces an oscillative torque with a double supply frequency. When asymmetrical voltages controlled by the triacs are applied to the motor, the voltage and current behaviors are distorted. The authors have proposed a countermeasure of the insertion of ferrite magnetic wedges into the motor slot openings to smooth the flux density pulsation across the air gap. As a result, some significant relationships have been obtained.
Electrooptic Characteristics of Amino-Gel-Glass-Dispersed Liquid Crystal and Its Matrix Formation
Authors: Chang Win-Pin , Wha-Tzong Whang Wha-Tzong Whang , Jaw-Ching Wong Jaw-Ching Wong
Published: October 2002

The gel-glass-dispersed liquid crystals (GDLCs) from amino-silicon alkoxides have successfully been prepared in a short time by sol-gel process. Those GDLCs had the same operation mechanism and performances as polymer-dispersed liquid crystal (PDLC). The electrooptic characteristic of the GDLC strongly depended on the composition of raw materials and the concentrations of liquid crystal. Titanium ethoxide was used successfully to adjust the refractive index of the gel-glass matrix, but it caused the gel-glass to be less flexible and the GDLC operated at a higher voltage. GDLC-13 had a reasonable operation voltage of 13 V, a good on-state transmittance of 100%, and a good contrast of 16.2. The introducing of a two-functional amino silane, (3-[diethoxymethylsilyl] propylamine), in the composition of matrix raw materials offered the gel-glass matrix better flexibility, higher conductivity, and greater capacity for trapping liquid crystal. It resulted in a significant improvement of the electrooptic characteristic of the GDLC
Determination of the Optical Constant Profiles of Thin Weakly Absorbing Inhomogeneous Films
Authors: Liou Yeuh-Yeong , Lee Cheng-Chung , Jaing Cheng-Chung , Chu Cheng-Wei , Jin-Cherng Hsu Jin-Cherng Hsu
Published: October 2002

The expression for the transmission of a thin weakly absorbing inhomogeneous film on a thick finite transparent substrate is manipulated to yield formulas for the refractive index and extinction coefficient. A procedure based on the envelope method is presented to determine the optical constant profile, the inhomogeneity, the mean refractive index, the degree of inhomogeneity, and the thickness of a film. Only the information contained in the transmission monitoring curve is used and the process is simple, fast and can be easily carried out using a personal computer. The procedure presented in this paper can be used as a means of investigating the degree of inhomogeneity and the absorption of the films deposited by different coating methods and deposition conditions. It is shown that TiO2 film deposited on a heated substrate has a more desirable optical constant profile than one deposited on an unheated substrate. For ZrO2film deposited on a heated substrate, the degree of inhomogeneity is greater whereas the absorption is lower than those of TiO2films.
Mechanism of Secondary Ion Emission from Silicon Dioxide Bombarded with Argon Ions
Authors: Tamaki Shozo , Yamauchi Naohiko , Kuroda Tsukasa , Yagi Hideichi
Published: October 2002

SiO2 powder which includes oxygen of both mass numbers 16 and 18 was Ar+-bombarded in a high vacuum and in 16 O2 gas at various pressures. Dependence of the secondary-ion currents on the oxygen pressure was used to consider the secondary ion formation mechanism, and the total current for SiO+ was separated into three parts corresponding to the following mechanisms: (I) atomic-bond breaking in SiO2 molecules, (II) ionization of SiO* (SiO in an excited, neutral state) formed by bond breaking through an interaction with oxygen, and (III) combination of Si* formed by bond breaking with gas-phase oxygen. The first mechanism was proven to be independent of the amount of adsorbed oxygen on the sample surface. SiO+ formed by the third mechanism increased proportionally with the oxygen pressure. Interaction of SiO* with oxygen in the second mechanism did not show a simple relationship with the pressure.
Diagnostic Experiment and Kinetic Model Analysis of Microwave CH4/H2Plasmas for Deposition of Diamondlike Carbon Films
Authors: Tahara Hirokazu , Minami Ken-ichiro , Murai Akira , Yasui Toshiaki , Takao Yoshikawa Takao Yoshikawa
Published: October 2002

Medium-pressure CH4/H2plasmas were generated in a discharge tube on the axis of a cylindrical 2.45-GHz-microwave TM011-mode-resonance cavity for chemical vapor deposition of diamondlike carbon films. Diamondlike carbon synthesis, plasma diagnostic measurements and kinetic model analyses were conducted to examine the correlation between plasma properties and film features. The characteristics of the calculated H-atom density of the excitation quantum level 4 agreed with those of the measured spectral intensity of the Hβ line. Consequently, high density ratios of C atoms to H atoms were required for deposition of diamondlike carbon. On the other hand, the density ratio of CH3radicals to H atoms was considered to be closely related to the hardness of deposited diamondlike carbons.
Anisotropic Heating of a Copper and Graphite Powder Mixture during an Electrical Column Explosion
Authors: Miyakawa Shin , Burkhard Günther , Tamura Hideki , Tanabe Yasuhiro , Akira B. Sawaoka Akira B. Sawaoka
Published: October 2002

An electrical column explosion of a copper and graphite powder mixture was investigated and one possible model was established, in which such a powder mixture is anisotropically heated by an electric current due to the difference in resistivities of the constituents. One of the constituents of the powder mixture reaches its boiling point at a shorter time, thus leading to the column explosion.
Role of Point Defects in Dielectric Breakdown of SiO2 Formed by Plasma-Enhanced Chemical Vapor Deposition of Tetraethoxysilane
Authors: Ishii Keisuke , Isshiki Daisuke , Ohki Yoshimichi , Nishikawa Hiroyuki , Takiyama Makoto
Published: October 2002

The intrinsic breakdown strength of thin SiO2 films formed by plasma-enhanced chemical vapor deposition of tetraethoxysilane was measured using a self-healing technique by applying short-duration voltage pulses. Point defects in the films and other film qualities were examined by instrumental analyses and by optical absorption and luminescence using synchrotron radiation. The intrinsic breakdown strength decreases when the deposition temperature becomes higher than 400° C, in spite of the fact that the optical gap and the density increase and the impurity content decreases. Based on the fact that the film deposited at high temperatures shows absorption at 7.6-eV and luminescence at 4.4-eV, the existence of oxygen vacancies ( ≡Si-Si≡) is suggested. The intrinsic breakdown strength is increased by decreasing oxygen vacancies through oxygen treatment. From these results, it is considered that oxygen vacancies play a crucial role in lowering the breakdown strength. Three possible mechanisms are discussed.
Electromechanical Properties of Hot-Pressed Pb(Fe1/2Ta1/2)O3 Ferroelectric Ceramics
Authors: Masaru Yokosuka Masaru Yokosuka
Published: October 2002

Investigations were conducted on the ferroelectric properties of P
b(F
e
1/2
T
a
1/2)O
3 ceramics, in particular, on the electromechanical properties. Dense ceramic specimens prepared by the hot-pressing technique were used in this study. At the temperature of 158 K, the following values were obtained: ε
T
33/ε
0=1450, P
r=10.8 µ C/cm2, k
33=0.390 and d
33=131×10-12 C/N. These values were briefly compared with those of Pb(Fe1/2Nb1/2)O3 ceramics.
Hot Spots and Electron Heating Processes in a Helicon-Wave Excited Plasma
Authors: Nakamura Keiji , Suzuki Keiji , Hideo Sugai Hideo Sugai
Published: October 2002

Two-dimensional cross-field measurements of ArII optical emission induced by hot electrons ( >19.2 eV) are made to investigate the mechanism of rf power deposition in a helicon-wave excited plasma. Hot spots of the optical emission are observed near the walls underneath the antenna conductor carrying the axial rf current. This suggests the significant electron heating by the axial electric field of antenna near-fields. Time-resolved emission measurements reveal the heating time of ∼1 µ s for the hot spots and ∼10 µ s for the bulk plasma where the wave fields dominate the near-fields.
Control of Ion Energy for Low-Damage Plasma Processing in RF Discharge
Authors: Naoyuki Sato Naoyuki Sato , Hideki Kobayashi Hideki Kobayashi , Toshio Tanabe Toshio Tanabe , Takashi Ikehata Takashi Ikehata , Hiroshi Mase Hiroshi Mase
Published: October 2002

A new control technique for ion energy is based on the external electron injection into the capacitively coupled rf plasma using an auxiliary plasma source. The externally injected electrons replace the plasma electrons carrying the rf current and then reconstruct the rf sheath in which ions are accelerated. The experiment is carried out by using a parallel-plate rf plasma device with a magnetron discharge plasma source mounted behind the mesh grounded electrode. The experimental results show that the energies of ions are continuously controlled by varying the amount of injected electrons in a wide range from ≃(1/2)e
V
rf to ≃T
e, and this result agrees with that derived from our simple model.
Real-Time Monitoring of Silicon Nitride Composition During Plasma Enhanced Chemical Vapor Deposition
Authors: III Andrew D. Bailey , Richard A. Gottscho Richard A. Gottscho
Published: October 2002

The study of bulk and interfacial material properties during thin film deposition or growth is important for learning how to optimize and control processing conditions. Unfortunately, there have been no techniques available that offer simultaneously non-intrusive in situ monitoring, sufficient sensitivity to permit real-time data acquisition, and chemical specificity to determine how process parameters affect composition. In this work, we demonstrate that attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy can be used to provide all these capabilities for the study of plasma enhanced chemical vapor deposition of amorphous, hydrogenated silicon nitride (a-SiN:H). We use this technique to develop a low temperature deposition process where bulk H concentrations are low enough that the material could be useful as a thin film transistor gate dielectric. At the interface between the single crystallne Si substrate and the a-SiN:H layer, we observe a thin layer where the concentration of -Si-H is enriched. The appearance of two distinct absorption bands at 2190 cm-1 and 2050 cm-1 suggests that this interfacial layer is formed by amorphisation and hydrogenation of the single crystalline Si substrate. At the interface between the deposited nitride and the reactive plasma, there is an enriched layer of -N-Si-H that appears to act as an intermediate to a-SiN:H growth.
Effects of Polysilicon Electron Cyclotron Resonance Etching on Electrical Characteristics of Gate Oxides
Authors: Kang Tzong-Kuei , Ueng Shih-Yuan , Dai Bau-Tong , Chen Liang-Po , Huang-Chung Cheng Huang-Chung Cheng
Published: October 2002

In spite of the small amount of damage induced by Electron Cyclotron Resonance (ECR) etching, the radiation damage due to vacuum ultraviolet (VUV) photons from the high-density plasma still causes several problems. The leakage currents of the metal-oxide-semiconductor (MOS) capacitors with ECR-etched polysilicon gates are found to be higher than those of the control with wet etching. The leakage mechanism is therefore investigated in detail. The ions and radicals of the ECR plasma can directly attack the peripheral gate oxide and form the surface-damaged layer. In addition, the VUV photons will deeply impact the oxide interior and induce positive charges and interface trap states. A dilute HF solution can effectively remove the surface damage layer. Annealing at 400° C for 30 min can eliminate completely the positive charges. Furthermore, the SiO2/Si interface trap states are completely removed as the annealing time is raised to 60 min.
Growth and Optical Characterization of Cr3+:YAB and Cr3+:YGAB Crystal for New Tunable and Self-Frequency Doubling Laser
Authors: Makoto Iwai Makoto Iwai , Yusuke Mori Yusuke Mori , Takatomo Sasaki Takatomo Sasaki , Sadao Nakai Sadao Nakai , Nobuhiko Sarukura Nobuhiko Sarukura , Zhenlin Liu Zhenlin Liu , Yusaburo Segawa Yusaburo Segawa
Published: October 2002

We have grown Cr3+-doped huntite-borate crystals Cr3+:YAB and Cr3+:YGAB by the top-seeded solution growth (TSSG) method. These crystals have a broad fluorescence ranging from the red to near-IR spectral region, and their lifetimes were measured as 170 µs and 87 µs, respectively. The emission cross sections are estimated to be 0.8 ×10-20and 1.6 ×10-20cm2, respectively. The vibronic levels of their ground state were estimated to be ≈1400 cm-1, so they can provide a four-level system. The optical gain of Cr3+:YAB crystal was measured in the range from 744 nm to 852.5 nm. The maximum single-pass gain was 1.9 at 830 nm. Second harmonic generation in the UV region (375 nm) was obtained by a Cr3+:YAB crystal with 1.5 times higher conversion efficiency compared with LBO crystal. Consequently Cr3+:YAB crystal and Cr3+:YGAB crystal have potential as new self-frequency doubling laser materials with tunability.
X7R Lead-Complex Perovskite Dielectrics with Inhomogeneous Compositional Distribution
Authors: Uchikoba Fumio , Ito Takashi , Shigeyuki Nakajima Shigeyuki Nakajima
Published: October 2002

Excess- WO3 Pb(Mg1/2W1/2)O3-PbTiO3-Pb(Ni2/3Nb2/3)O3 polycrystalline dielectric material was investigated. This material met EIA X7R specifications (the change of the capacitance is less than 15% over the temperature range from -55° C to +125° C). The material showed inhomogeneous compositional distributions within grains that consisted of three main parts, each possessing a different temperature dependence of the dielectric constant. It was found that the flat-temperature dependence of the dielectric constant in this system could be attributed to this inhomogeneous compositional distribution. Using this material, multilayer ceramic capacitors were fabricated.
In Situ Monitoring of Selective Copper Deposition Processes in a Metal-Organic Chemical Vapor Deposition Using Fourier-Transform Infrared Reflection-Absorption Spectroscopy
Authors: Hanaoka Ken-ichi , Ohnishi Hiroshi , Kunihide Tachibana Kunihide Tachibana
Published: October 2002

Selective copper deposition processes on titanium nitride (TiN) substrates were investigated by in situ Fourier-transform infrared reflection-absorption spectroscopy and ex situ X-ray photoelectron spectroscopy. Bis-hexafluoroacetylacetonato-copper ( Cu(HFA)2) was used as a source material in a mixture with hydrogen gas. Continuous copper deposition did not occur when the native oxide on the TiN substrates was removed, because the substrate surface was fluorinated by CF2H groups and F atoms which came out from the decomposed CF3 groups in the HFA ligands. On the other hand, thin copper films deposited continuously when the native oxide was present on the TiN substrates. In addition, the copper deposition did not occur on the thermally oxidized silicon ( SiO2) substrates. From these results, it became clear that the selective copper deposition was governed by the conductivity of the substrate, and the presence of the unstable oxygen atoms on the surface, which were produced by the reduction of the unsteady oxide with hydrogen, promoted the film growth.
Reduction in Microloading by High-Gas-Flow-Rate Electron Cyclotron Resonance Plasma Etching
Authors: Kofuji Naoyuki , Tsujimoto Kazunori , Kumihashi Takao , Shin'ichi Tachi Shin'ichi Tachi
Published: October 2002

High-gas-flow-rate electron cyclotron resonance plasma etching was employed to reduce microloading in Si etching with Cl2at low pressure. Microloading estimated with a conventional etching system increases with decrease in pressure from 5 to 0.5 mTorr. The increase in microloading is attributed to the increase in the ratio of ion flux to reacting neutrals. The ion/neutral ratio was found to be as large as 6.4 at 0.5 mTorr. This large ratio was caused by both the decrease in reacting neutral density and the increase in reaction products. The high gas flow rate with a high effective pumping speed of 2000 l/s reduces the reaction products, increases the reacting neutrals and reduces the ion/neutral ratio to 0.65. As the result, the microloading is reduced. The relative etch rate at an aspect ratio of 7 increases from 0.65 at 136 l/s to 1.00 at 2000 l/s. Thus high-gas-flow-rate-etching solved the problem of large microloading which is not suppressed even with high density plasma and low gas pressure.
Elastic Vibrations of Fractal Networks
Authors: Tsuneyoshi Nakayama Tsuneyoshi Nakayama
Published: October 2002

Fractals are familiar as objects that look the same under different magnifications (self-similar structures) and the concept of fractal has spurred intense efforts to study such structures. The concept is useful for the definition of static structural properties. It can also be useful in describing the dynamical properties of fractal networks. This review describes recent research on elastic vibrations of fractal structures including the results of both scaling arguments and large-scale computer simulations.
Orientation and Crystal Structure of SrTiO3 Thin Films Prepared by Pulsed Laser Deposition
Authors: Hiratani Masahiko , Imagawa Kazushige , Kazumasa Takagi Kazumasa Takagi
Published: October 2002

SrTiO3 thin films are grown on MgO(001) substrates at growth temperatures between 600-800° C and at oxygen pressures between 10-1-10-6 Torr. The initial stage of growth is controlled by graphoepitaxy with a cube-on-cube orientation. In the growth temperature range from 600° C to 740° C, graphoepitaxy occurs only at 10-6 Torr or 740° C. At 10-6 Torr the internal and kinetic energies of the evaporated particles contribute to the surface mobility necessary for graphoepitaxy, while at 740° C heat energy assures surface migration. However, at 800° C, the orientation changes to (111) with increasing thickness. This is because the dominant factor of film growth changes to the formation of a close-packed surface as the growth front gets farther from the substrate surface.
Compact Vibratory Gyroscope
Authors: Shuta Kouichi , Hiroshi Abe Hiroshi Abe
Published: October 2002

This paper presents a piezoelectric-ceramic vibratory gyroscope with a vibrator that has fewer electrodes than a conventional gyroscope, and a method using driving and detecting circuits. This circuit can compensate the decrease of the scale factor due to miniaturization of the gyroscope. The vibrator of this vibratory gyroscope consists of a piezoelectric-ceramic cylinder with four electrodes. The two electrodes facing each other are used for picking up, and connected to two current-detecting circuits, and the other two electrodes facing each other are used for applying opposite-phase voltages to drive the vibrator. This design is promising for miniaturization of the vibratory gyroscope with the same scale factor as a conventional gyroscope.
Theoretical Study on Discretely Weighted Conical Transducers
Authors: Takashi Koike Takashi Koike , Ken Yamada Ken Yamada , Kiyoshi Nakamura Kiyoshi Nakamura
Published: October 2002

Conical transducers with weighted velocity distribution have been proposed by us for generating Bessel-type quasi-nondiffracting beams. In this paper discretely weighted structures are presented that will facilitate the fabrication of weighted conical transducers, and their sound fields are examined theoretically. It is shown that divided-conical transducers composed of a segmented cone with discrete weighting can create sound fields almost the same as those for the continuously weighted complete conical transducers.
Supporting Method of Resonators Using the Dynamic Damper
Authors: Kaida Hiroaki , Jiro Inoue Jiro Inoue
Published: October 2002

The paper describes a supporting method of resonators using the dynamic damper, and its effectiveness is analyzed by means of the finite-element method analysis and experiments. The supporting structure of a resonator wherein the cross bar is provided at the vibration-transmitting part is proposed. It is ascertained that when the ratio of resonant frequency of the resonator to that of the cross bar is set to be approximately 1, the cross bar functions as the dynamic damper to suppress the transmitted vibration. In the experimental device the resonator having the dynamic damper shows good frequency characteristics when it is secured to the outer substrate.
Characteristics of Leaky Surface Acoustic Waves Propagating on LiNbO 3 and LiTaO 3 Substrates
Authors: Shigetaka Tonami Shigetaka Tonami , Atsuhiro Nishikata Atsuhiro Nishikata , Yasutaka Shimizu Yasutaka Shimizu
Published: October 2002

Two types of leaky waves are obtained in this paper. They are the first leaky wave, whose phase velocity is between those of slow and fast shear waves, and the second leaky waves, whose phase velocity is greater than that of the fast shear wave. The characteristics of leaky waves propagating on LiNbO3 and LiTaO3 substrates are theoretically investigated by changing cut angles and propagating directions. Propagation loss of the first leaky wave for an electrically open surface becomes almost zero at φ=20, 40, 80, 100, 140 and 160° on ( φ, 90°, 0°)-cut LiNbO3 substrate, and K
2 is 16.2% at these cuts. Phase velocities of the second leaky waves propagating on (90°, 90°, ψ )-cut LiTaO3 and LiNbO3 substrates are twice as fast as those of Rayleigh waves, and electromechanical coupling coefficient (K
2) of 2.14% is obtained at ψ=31° on the LiTaO3 substrate. Propagation losses of both electrically open and short surfaces are almost zero at ψ=164° on the LiTaO3 substrate. K
2 of as high as 12.9% is obtained at ψ=36° on the LiNbO3 substrate. Propagation losses of both electrically open and short surfaces are almost zero at ψ=163° on the LiNbO3 substrate.
Epitaxially Grown Aluminum Film on Rotated Y-Cut Lithium Niobate for High-Power Surface Acoustic Wave Devices
Authors: Sakurai Atsushi , Nakanishi Hidefumi , Yukio Yoshino Yukio Yoshino
Published: October 2002

Epitaxially grown aluminum (Al) films for high-power surface acoustic wave (SAW) devices were formed in various orientations on rotated Y-cut lithium niobate ( LiNbO3) substrates by using the dual-ion-beam sputtering (DIBS) method. The (111) plane of every Al film on LiNbO3 is parallel to its surface in our experiments.
Quasi-Microwave Band Longitudinally Coupled Surface Acoustic Wave Resonator Filters Using ZnO/Sapphire Substrate
Authors: Koike Jun , Tanaka Hiroshi , Hideharu Ieki Hideharu Ieki
Published: October 2002

The 1.5 and 2.4 GHz range 5IDT-type longitudinally coupled surface acoustic wave (SAW) resonator filters have been developed using ZnO/sapphire substrate. The 1.5 GHz range SAW filter has the minimum insertion loss of 1.0 dB and the relative bandwidth of 2.4% at the insertion loss of 3 dB.
The 2.4 GHz range SAW filter has the minimum insertion loss of 1.7 dB and the relative bandwidth of 1.7% at the insertion loss of 3 dB.
These filters are suitable for use as RF-stage filters in a personal digital cellular (PDC) system terminal and a wireless local area network (LAN) adapter, respectively.
Study on Power Durability of Ti-Containing Al Surface Acoustic Wave Electrodes, Using Interdigitated Interdigital Transducer Filters
Authors: Ota Yasuhiro , Akitsuna Yuhara Akitsuna Yuhara
Published: October 2002

The power durability of Al-0.6 wt%Ti electrodes in 900 MHz interdigitated interdigital transducer surface acoustic wave (IIDT SAW) filters was investigated through accelerated time-to-failure (TF) tests in relation to grain sizes and annealing, and was further compared with that of pure Al, Al-0.5 wt%Pd and conventional Al-1.1 wt%Cu electrodes. TF of the Al-0.6 wt%Ti electrodes in the IIDT filter is increased by reducing the average grain size and the standard deviation of the grain size. Annealing of Al-0.6 wt%Ti film, however, results in increase of the average grain size and decrease of TF.
TF of Al-0.6 wt%Ti electrodes was the largest: much larger than that of Al-0.5 wt%Pd electrodes, having almost the same grain size and standard deviation as Al-0.6 wt%Ti electrodes, and nine times as large as that of Al-1.1 wt%Cu electrodes.
Surface Acoustic Wave Characteristics on ZnO/\mbYZ·LiNbO 3 Structure and Their Application to Elastic Convolver
Authors: Michio Kadota Michio Kadota , Kunio Minami Kunio Minami
Published: October 2002

In an effort to improve the efficiency of an elastic convolver, we discussed ways to increase the electromechanical coupling factor of the LiNbO3 (LN) substrate. We examined, both theoretically and experimentally, the surface acoustic wave (SAW) characteristics of ZnO films formed on the +Y· and -Y·planes of the Y
Z·LN substrates. As a result, it was clear that a larger electromechanical coupling factor, k
s, can be obtained with a ZnO film on the +Y·plane than on the -Y·plane of Y
Z·LN substrates. The maximum value of the coupling factor obtained was 0.32, which was 2.04 times the square (k
s
2) of the value obtained without the ZnO film. By applying the LN substrate with the ZnO film on its +Y·plane to the elastic convolver, we obtained a processing time of 7.6 µs, a 3 dB bandwidth of 44 MHz and an efficiency of -58 dBm.
Analyses of an Ultrasonic Motor Driving Fluid Directly
Authors: Hu Junhui , Yamazaki Tohgo , Nakamura Kentaro , Ueha Sadauki
Published: October 2002

This paper presents an analysis of acoustic field and flow in an ultrasonic motor using fluid. The inside of a stator cylinder is filled with fluid. The fluid is caused to flow in the circumferential direction by the ultrasonic vibration traveling along the cylinder. It is revealed that shearing Reynolds' stress in the fluid is the driving force of the flow in this motor. According to the analytical method stated in this paper, we simulate and discuss some characteristics of this motor. In conclusion, the guideline for the optimum design of the motor is proposed, which is to tune the resonance frequency of the fluid field to that of the vibrating cylinder containing the fluid.
Ultrasonic Linear Motor Using Multilayer Piezoelectric Actuators
Authors: Funakubo Tomoki , Tsubata Toshiharu , Taniguchi Yoshihisa , Kumei Kazuhiro , Fujimura Takanao , Abe Chikara
Published: October 2002

In order to lower operating voltage and improve the lifetime of an ultrasonic linear motor, we have developed an ultrasonic oscillator with multilayer piezoelectric actuators. Multilayer piezoelectric actuators are operable at low voltage. However, the tensile strength of the multilayer piezoelectric actuator is small. Therefore, the multilayer piezoelectric actuators are build within an elastic body to lower the tensile stress with a compressive preload. Elliptical oscillations are generated by synthesizing two degenerated modes, a first longitudinal mode and a second flexural mode, with π/2 phase difference. As a result of estimating the characteristics of the ultrasonic linear motor with the ultrasonic oscillator, the operating voltage of 10 V
p-p
, maximum thrust force of 8 N and lifetime of over 5000 hours have been obtained.
Wear Properties and Life Prediction of Frictional Materials for Ultrasonic Motors
Authors: Ishii Takaaki , Ueha Sadayuki , Nakamura Kentaro , Ohnishi Kazumasa
Published: October 2002

The characteristics and life of an ultrasonic motor are strongly related to the frictional material used on the sliding surface, because the motor is driven by frictional force and its life is limited to that of the frictional material. Hence wear evaluation of the frictional material is necessary for life prediction of the ultrasonic motor. In this experiment, the wear of carbon-fiber-reinforced plastics (CFRP) used as frictional material in ultrasonic motors is evaluated. The specific wear rate is derived from a simple wear test and is applied to estimate the wear of the CFRP used in the ultrasonic motor. The life of the ultrasonic motor, as well as that of frictional material, can be estimated using the equation derived from the experiment.
Lateral Force Modulation Atomic Force Microscope for Selective Imaging of Friction Forces
Authors: Yamanaka Kazushi , Tomita Eisuke
Published: October 2002

An approach to imaging friction force distribution on the nanometer scale is presented, where a sample is laterally vibrated and both the amplitude and the phase of resultant torsion vibration of the cantilever are employed for imaging. It has an advantage over the conventional friction force microscope (FFM) in that the contrast due to local gradient can be significantly reduced. The topographic contrast was almost completely suppressed on a gold evaporated film sample. A method for characterizing friction, the friction force curve (FFC), is proposed where the friction force amplitude and phase are recorded simultaneously with the normal force, as a function of the tip-sample distance. The usefulness of the FFC was verified in characterizing slip and deformation in the tip-sample interaction.
Module Stellarator System Made of L =±2 Helices with Different Pitch Angles
Authors: Sato Suguru , Kogoshi Sumio , Katsurai Makoto
Published: October 2002

A new design method for the modularization of helical coils of a stellarator type has been proposed. This is an extension of the interchangeable module stellarator (IMS) method, andL=±2 helices with different pitch angles are utilized. This modular coil system exerts less error field effects on magnetic properties, so it may have large magnetic surfaces. The magnetic axis exists nearly at the coil center without any additional fields. It may have larger transform than that designed from the original IMS method.
Optical Mode Conversion by Magnetostatic Surface Waves in Optical Waveguide-Type Devices Using Cerium- and Bismuth-Doped Garnet Crystalline Films
Authors: Shin'ichiro Kikuchi Shin'ichiro Kikuchi , Yasumitsu Miyazaki Yasumitsu Miyazaki
Published: October 2002

Optical devices using magnetostatic surface waves (MSSWs) have important applications in optical signal processing and optical computing. In this paper we propose the analysis and design of an optical mode conversion device that features improved switching efficiency achieved by the use of a new material with increased magneto-optic effect. The device consists of cerium- and bismuth-doped thin and thick garnet films. The design features 100% mode conversion over an interaction length of about 5 mm for an applied microwave power density in the range 1–10 mW/mm. Cerium- and bismuth-doped Yttrium Iron Garnet (YIG) films are fabricated by rf sputtering and their crystal properties are studied using X-ray microanalyzer and X-ray diffractometer.
Radication Power Output for Two-Dimensional Array of Transducers in Water Using Farfield and Nearfield Techniques
Authors: Tomikawa Kiyotaka , Hasegawa Akio , Kikuchi Toshiaki , Tsuchiya Toshio
Published: October 2002

The radiation efficiency for a two-dimensional array of transducers is determined from the acoustic power radiated to the farfield, i.e., the farfield technique. The radiation efficiency curves can be classified into three types: (a) quadrupole type (even-even mode), (b) dipole type (even-odd mode) and (c) monopole type (odd-odd mode) as suggested by Maidanik1) for a vibrating panel. To attain a global reduction in the farfield intensity, the power output of individual transducers must be considered when designing or evaluating an active sound power control. The power output radiated from individual transducers is then determined using the nearfield technique based on the self- and mutual radiation impedances. The agreement between theoretical and experimental results is satisfactory.
Lower Lamb Wave Resonance Mode of Thin Cylindrical Shells
Authors: Shibata Hiroshi , Tsuchiya Toshio , Kikuchi Toshiaki , Akio Hasegawa Akio Hasegawa
Published: October 2002

Recently, the need for a low-frequency acoustic source for oceanic observation and long-distance propagation in the sea has been increasing. A cylindrical resonator-type sound source is proposed as one of the low-frequency acoustic source. However, sound sources of this type have a disadvantageous point in that the cylinder size becomes greater in the lower-frequency range. Accordingly, we study the lower Lamb wave resonance mode of thin cylindrical shells and investigate the possibility of miniaturizing this type of sound source. We analyze the resonance characteristics of the axial vibration mode, circumferential vibration mode and coupling vibration mode using thin cylindrical shells.
Electron Phase Microscopy and Its Applications to the Observation of Vortex Dynamics
Authors: Akira Tonomura Akira Tonomura
Published: October 2002

The development of a coherent electron beam has opened a way to measure, byelectron holography, the phase distribution of an electron beam transmitted through a phase object to a precision within 1/100 of the wavelength and to observe vortex dynamics byLorentz microscopy(defocused electron microscopy under collimated illumination). Objects and fields on the microscopic level, which have been previously inaccessible, are thus becoming observable. Examples are the measurement of a magnetic field distribution inside a vortex and the dynamic observation of vortices.
Lattice Location of 15N Atoms in SiC Analyzed by Nuclear Resonant Reaction
Authors: Ito Tadashi , Konomi Ichiro , Azuma Hirozumi , Shoji Noda Shoji Noda
Published: October 2002

The nuclear resonant reaction 15 N(p, αγ)12 C and channeling effect of proton beams have been applied to the study of the lattice location of ion-implanted 15N atoms to a dose of 1×1016
15N2
+/cm2 at an energy of 100 keV in 6H-SiC.
The structural recovery of the damaged layer has also been studied by the conventional Rutherford backscattering technique combined with channeling effect measurements. Elevated-temperature implantation, in particular, at above 1000° C, facilitates substitution of the 15N atoms into the SiC lattice sites as well as implantation-induced-damage reduction of the SiC host crystal. Postimplantation annealing (at 1300° C) promotes the recovery of the damaged layer. However, it does not promote the substitution of 15N atoms.
Contact Resistivity and Adhesion of Ni/AuGe/Ag/Au Ohmic Contact Directly to n-Type AlGaAs
Authors: Ehara Takashi , Shibata Naoki , Ohta Hirokazu , Nukui Tohru , Tadao Kazuno Tadao Kazuno
Published: October 2002

The direct ohmic contact to AlGaAs, Ni/AuGe/Ag/Au=5/120/100/580 nm has been studied. Contact resistivity of 3.8×10-5 Ω cm2 is obtained after thermal treatment for 10 min at 450° C. This is one order lower than that of the conventional Ni-Ge-Au system. The new metallization also indicates strong adhesion on SiN
x
film, does not peel off even after thermal treatment during all device processes and withstands the wire bonding process. We conclude that the metallization is useful and applicable for AlGaAs-related devices.
Electrical Properties of Paraelectric (Pb 0.72La 0.28)TiO3 Thin Films with High Linear Dielectric Permittivity: Schottky and Ohmic Contacts
Authors: Dey Sandwip K. , Lee Jong-Jan , Prasad Alluri Prasad Alluri
Published: October 2002

Linear, paraelectric (Pb0.72La0.28)TiO3 or PLT(28) thin films with a bandgap>3 eV were deposited on Pt/Ti/SiO2/Si substrates by the sol-gel technique. Specific top-contact metals from two distinct groups (i.e., non-noble or M
T and noble or M
N; the former being oxidizable transition metals) were selected to understand the electrical nature of the interfaces in terms of electrode dependent energy band diagrams and equivalent circuit models. Using a high sensitivity high-pass filter circuit to evaluate the charging and discharging behavior coupled with results of the thickness and voltage dependence of capacitance, it was determined that M
T ( Ni,Cr,Ti) and M
N ( Pt,Au,Ag) metals form Ohmic and Schottky contacts, respectively. Supported by thermochemical data and calculations, the ohmic M
T- PLT interfaces are envisioned to be of the form: M
T-M
T O
x
-n
+ PLT-n PLT. In contrast, the M
N- PLT interfaces may be characterized by a metal work function independent Schottky diode; the surface Fermi level being pinned at the mid-gap. For example, a Schottky barrier height of 1.83 eV and a built-in voltage of 1.3 eV at the Pt-PLT interface were estimated. From low field capacitance measurements, the ratio of interfacial to bulk resistance, R
i/R
b, was estimated to be 23.
Surface Defects and Local Strain in Polished Silicon by Transmission Electron Microscopy
Authors: Saito Tomohiro , Doke Yasuo , Sakaida Yoshihisa , Yuichi Ikuhara Yuichi Ikuhara
Published: October 2002

Surface defects and local strain in polished silicon were characterized by cross-sectional transmission electron microscopy (XTEM) and convergent beam electron diffraction (CBED). Dislocations are introduced from the surface by polishing with diamond slurry, and their main slip system was found to be 1/2<101>{111}. The depth of the dislocation-introduced zone deepens with increasing diamond particle size, however, the density of dislocations is fairly high for materials polished with particles of small size. This is because the stress between particle and surface increases with increasing particle size, and the particle density increases with decreasing particle size. Local strain remains up to a depth of 1-1.5 µ m beneath the surface for samples polished with 0.5 to 6 µ m diamond slurry. This residual stress is distributed approximately 1 µ m below the dislocation-introduced zone.
A Novel Shearing Interferometer with Direct Display of Lens Lateral Aberrations
Authors: Matsuda Kiyofumi , Eiju Tomoaki , Barnes Thomas H. , Shigeru Kokaji Shigeru Kokaji
Published: October 2002

We describe a new shearing interferometer for lens testing which has high precision and direct display of lens aberrations. Shear is obtained by reflecting a wavefront collimated by the lens under test from the front and rear surfaces of a wedged glass plate. The surfaces of the plate are coated to increase their reflection coefficient and give sharp multiple beam interference fringes which are easy to measure and interpret. We show mathematically that the interference fringes map out the lateral aberration curve of the lens under test directly, and present experimental results which display the advantages of this system over conventional two-beam shearing interferometers.
Origin of the Blue Shift Observed in Highly Strained (Ga, In)As Quantum Wells Grown on GaAs(001) Vicinal Surfaces
Authors: Leroux M. , Grandjean N. , Deparis C. , Massies J. , Lopez C. , Mayoral R. , Meseguer F.
Published: October 2002

The photoluminescence energy of strained (Ga, In)As quantum wells grown on (001) GaAs slightly misoriented (2°-6°) towards (111)A exhibits a blue shift when compared to quantum wells grown on perfectly oriented substrates. It is shown that this observation is linked to a blue shift of intrinsic ground state excitonic transition energies. This effect is studied as a function of substrate misorientation angle, well width and indium surface segregation level. In order to understand its origin, various hypotheses were examined: regular shrinkage of well width due to terrace edges, additionnal stress of the well material at the step edges, and orientation dependent In segregation. It appears that the first two combined effects provide the best description of the experimental tendency.
First-Principles Calculation of Effective Mass Parameters of Gallium Nitride
Authors: Masakatsu Suzuki Masakatsu Suzuki , Takeshi Uenoyama Takeshi Uenoyama
Published: October 2002

The electronic band structure calculation is carried out for wurtzite-type GaN by using a full-potential linearized augmented plane wave (FLAPW) method. In order to give useful information on the material and device designs for short-wavelength optical devices, the first-principles calculation is connected with the effective mass approximation for the wurtzite structure. The effective mass parameters, such as electron effective mass, Luttinger-like parameters, crystal field splitting and spin-orbit splitting, are derived for the first time from reproducing the calculated band structure near the Γ point. The obtained value of the electron effective mass is in good agreement with the observed values. It is also found that the cubic approximation is available to analyze the valence band structure of the wurtzite-type nitrides.
Electrical and Optical Properties of CuInSe 2 Single Crystals Prepared by Three-Temperature-Horizontal Bridgman Method
Authors: Hiroaki Matsushita Hiroaki Matsushita , Tatsuhiko Suzuki Tatsuhiko Suzuki , Saburo Endo Saburo Endo , Taizo Irie Taizo Irie
Published: October 2002

Single crystals of CuInSe2 have been prepared by the three-temperature-horizontal Bridgman method. The crystals prepared under pressure higher than 10 Torr show p-type conduction and have a single phase, while those prepared under lower pressure show n-type conduction and contain a CuIn alloy phase. The crystals prepared under Se vapor pressure of 10 Torr have the largest Hall mobility and the smallest carrier concentration of all p-type crystals. The band tail spreads towards the low-energy side with increasing Se vapor pressure. It is considered that the p-type crystals have the acceptor level of ∼40 meV due to V Cu, and the donor level due to In Cu for Se vapor pressures higher than 25 Torr or due to V Se for Se vapor pressure of 10 Torr.
Effects of Silicon Nitride Chemical Composition on Magneto-Optical Properties of Non-Stoichiometric Silicon Nitride/TbFeCo Layers
Authors: Nakada Masafumi , Mitsuya Okada Mitsuya Okada
Published: October 2002

The effects of various silidon nitride chemical compositions on the magneto-optical properties of non-stoichiometric silicon nitride/TbFeCo layers have been investigated. With increasing pressure of the sputtering gas, stoichiometric Si3N4 changes to silicon oxynitride SiON, and with decreasing in the N2/Ar ratio of the sputtering gas, it changes to nitrogen-defective silicon nitride ( SiN

x

). The refractive index of films decreases with increasing oxygen concentration, and it increases with decreasing nitrogen concentration. Measured values for Kerr rotation angle and reflectivity of the SiN

x

/TbFeCo/SiN

x

layers were found to correspond quite well to those derived theoretically. Increase of the oxygen concentration of the SiON layer results in oxidation at the interface, which in turn results in an observable decrease in the Kerr rotation angle of SiON/TbFeCo bilayers. A SiN

x

/TbFeCo layer has been found to be just as effective as a Si3N4/TbFeCo layer for use in magneto-optical disks.