bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sputtering-Target Composition on the Texturization of LaNiO3 Thin Films on Si Substrate
Authors: Lee Hsin-Yi , Wu Tai-Bor , Lee Jyh-Fu
Published: October 2002

Highly (100)-textured LaNiO3 thin films were deposited on Si substrate via rf magnetron sputtering. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were employed to characterize the texturization of LaNiO3 thin films deposited with targets of various compositions and at different substrate temperatures. It was found that a slight increase of the Ni/La ratio in the composition of the target could compensate the Ni loss on high temperature deposition, leading to an improved (100)-textured film structure. However, for deposition with targets having Ni/La ratio larger than 1.4 or substrate temperature higher than 450°C, the Ni loss was repressed and the (100)-textured structure was also degraded. The XAS results reveals that the target composition and the substrate temperature influenced the local structure as well as the electronic configuration of Ni atom in the deposited films, but the environment around La atom was little affected. The extended X-ray absorption fine structure results indicate that the change of structural and electronic environment around Ni atom is owing to a significant amount of NiO phase formed in the films deposited with the targets of high Ni/La ratio or at high substrate temperatures.
Driving Electric Field Effects on Piezoelectric Transducers
Authors: Sadayuki Takahashi Sadayuki Takahashi , Yasuhiro Sasaki Yasuhiro Sasaki , Seiji Hirose Seiji Hirose
Published: October 2002

Electromechanical properties for lead zirconate-titanate Pb(ZrxTi1-x
)O3 (PZT) based ceramic and lithium niobate LiNbO3 (LN) crystal piezoelectric transducers were studied from a driving electric field viewpoint. The vibration velocity linearly increases with the driving field for a 128°-rotated Y-cut LN transducer and its maximum vibration velocity which can be used is 2.7 m/s when driven with the driving field of 7 ×102 V/m. The transducer is mechanically broken when driven with a higher field. The vibration velocity for the PZT based ceramic transducer initially increases with an increasing field and then gradually converges onto a certain value accompanied by heat generation. These phenomena are caused by the decrease in the mechanical quality factor with an increasing field. The 0.45PbZrO3–0.45PbTiO3–0.10Pb(Mn1/3Sb2/3)O3 ceramic transducer is capable of generating 0.68 m/s with 5.5 ×103 V/m.
Basic Investigation on Achieving High Resonance Quality Factor of Piezoelectric Vibrator
Authors: Hideki Tamura Hideki Tamura , Yoshiro Tomikawa Yoshiro Tomikawa , Chiharu Kusakabe Chiharu Kusakabe , Katsutoshi Sakurai Katsutoshi Sakurai , Kazumasa Ohnishi Kazumasa Ohnishi
Published: October 2002

This paper deals with basic experiments on achieving the high resonance quality factor of a piezoelectric vibrator by applying negative elements of the negative impedance converter (NIC) circuit. Based upon the method described here, the experiments have proven that the resonance quality factor of a piezoelectric ceramic vibrator could be increased by about 50 times, and moreover, in proportion to becomes the increase of the resonance quality factor, the measured displacement of the vibrator large.
Q-Value Control of Piezoelectric Vibrator Using Operational Amplifier Circuit
Authors: Kengo Yanai Kengo Yanai , Yoshiro Tomikawa Yoshiro Tomikawa , Katsutoshi Sakurai Katsutoshi Sakurai , Chiharu Kusakabe Chiharu Kusakabe
Published: October 2002

In application of a piezoelectric vibrator to some electronic devices such as gyro-sensors and piezoelectric ceramic transducers, it is very useful if the value of the resonance quality factor (Q-value) can be controlled electrically. For achievement of such an ideal, application of a negative impedance converter circuit (NIC circuit) to a piezoelectric vibrator is considered in this work. We applied several negative circuit elements to a piezoelectric vibrator in order to control the Q-value and achieve high performance of it. That is, this work deals with Q-value control of a piezoelectric vibrator by series connection of the NIC circuit, consisting of an operational amplifier, to the vibrator.
Finite Element Method Analysis of Single Crystal Tuning Fork Gyroscope for Suppression of its Inner Leakage Coupling
Authors: Noboru Wakatsuki Noboru Wakatsuki , Hiroshi Tanaka Hiroshi Tanaka
Published: October 2002

To suppress the null signals in a LiTaO3 crystal fork gyroscope, we analyzed the fork's vibration modes using the finite element method (FEM) and proposed adding a slit to the base of the fork. In the base with a slit, the movement of the f

x
mode is very low level but the symmetrical motion is the same as of the arm for the f

z
mode. Therefore, we can place a detecting electrode where the driving mode is negligible. Since the slit also improves the mechanical balance for the f

z
mode and suppresses a precessional motion, the mechanical coupling decreases to less than 1/10.
Properties of Alternately Poled Piezoelectric Transformers
Authors: Kanayama Kouichi , Maruko Nobuhiro
Published: October 2002

A piezoelectric transformer has been developed for use as a step-up transformer that is built into the CCFL (cold cathode fluorescent lamp) inverter. The CCFL is used for LCD (liquid crystal display) backlight functions. We developed a new type of piezoelectric transformer which has an alternately poled structure. It is able to illuminate a CCFL by applying half of the input voltage of the Rosen type piezoelectric transformer.
Highly Piezoelectric Shear-Horizontal-Type Boundary Waves
Authors: Takashi Yamashita Takashi Yamashita , Ken-ya Hashimoto Ken-ya Hashimoto , Masatsune Yamaguchi Masatsune Yamaguchi
Published: October 2002

This paper describes theoretical studies on piezoelectric shear-horizontal (SH) type boundary waves propagating along the surface of a separation between piezoelectric and non-piezoelectric materials. According to the guiding mechanism for this type of waves, it is expected that the application of highly piezoelectric materials results in a wide range of existence of combinations for various materials. Numerical analysis shows that SH-type leaky boundary waves exist for combinations of Si/LiNbO3, Si/LiTaO3 and YAG/LiNbO3. The electromechanical coupling factor K
2 of 10.0% is obtainable for SH-type leaky boundary waves in [001]-Si<110 >/175°YX-LiNbO3, in which the velocity is about 4,465 m/s and the attenuation due to leaky nature is substantially zero.
Characteristics of Surface Acoustic Waves Propagating on a La3Ga5SiO14 Substrate
Authors: Sato Takashi , Atsuhiro Nishikata Atsuhiro Nishikata , Yasutaka Shimizu Yasutaka Shimizu
Published: October 2002

La3Ga5SiO14 is structurally similar to quartz, and its good propagation characteristics are expected. A numerical analysis of the propagation characteristics of a Rayleigh wave on La3Ga5SiO14 is presented in comparison with those on quartz. The phase velocity on La3Ga5SiO14 is generally about 70% slower than that on quartz. The K
2 of La3Ga5SiO14 is about 2–3 times larger than that of quartz. A comparison of the propagation characteristics is made based on several material constants which have been reported so far. The temperature coefficient of delay (TCD) shows a relatively high difference.
Mass and Energy Analyses of Substrate-incident Ions in TiO 2 Deposition by RF Magnetron Sputtering
Authors: Kunio Okimura Kunio Okimura , Akira Shibata Akira Shibata
Published: October 2002

Mass-resolved measurements of substrate-incident ion (SII) current and ion kinetic energy distributions (IEDs) were carried out for TiO2 deposition by rf (13.56 MHz) magnetron sputtering. Substrate-incident ion current was mainly composed of Ar+, O2
+ and O+. Several minor ions, such as Ti+,TiO+, ArO+ and Ar2
+ were also detected. The dominant species of substrate-incident ion was O2
+ at a total pressure higher than 20 mTorr, while Ar+ was dominant one at a total pressure of 2 mTorr with which rutile TiO2 grew on a non-heated substrate. Variations in IEDs for Ar+ and O2
+ against total gas pressure, oxygen flow rate and applied rf power were presented. The energy with peak intensity in IED and the mean ion energy increased with both decreasing pressure and increasing rf power. Strong correlation between IEDs and the growth of crystallized TiO2 were observed. Finally we discussed the growth condition of rutile TiO2 films based on the results including the dc self-bias voltage.
A Study on Speed-Up of Ingredient Separation with Ultrasound in Semi-Permeable Tube Membrane
Authors: Masuzawa Nobuyoshi , Yoshimura Takehiro , Etsuzo Ohdaira Etsuzo Ohdaira , Masao Ide Masao Ide
Published: October 2002

Separation technology involving use of semi-permeable membranes is playing an important role in various fields of medicine and industry. Studies on reduction of separation time by use of ultrasound have been attempted. These studies have been mainly on plain flat membranes, though use of tube membranes has spread rapidly. In this paper circular irradiation of ultrasound using a cylindrical radiator which is appropriate for tube membranes is described. It was found that separation speed was 21% higher in the case of circular irradiation than in that of conventional flat irradiation.
Ultrasonic Probe for Detecting a Three-Dimensional Vibration
Authors: Koichi Mizutani Koichi Mizutani , Naoto Wakatsuki Naoto Wakatsuki , Keinosuke Nagai Keinosuke Nagai
Published: October 2002

We propose a contact ultrasonic probe which can detect a three-dimensional vibration and separate it into its X, Y and Z components. The performance is realized using two Lamb waves and a shear horizontal (SH) wave simultaneously. The vibration in the Y direction is detected using the zeroth-order symmetrical (S0) mode SH wave, which has a displacement in only the Y direction. Those in the X and Z directions are detected using the zeroth-order asymmetrical (A0) and S0 mode Lamb waves, respectively. In a region in which the substrate is thinner than the wavelength, the A0 mode Lamb wave has a displacement in only the X direction, and the S0 mode, only in the Z direction.
Sonic Field Measurement Using Light Computerized Tomography
Authors: Masahiro Yoshioka Masahiro Yoshioka , Koichi Mizutani Koichi Mizutani , Keinosuke Nagai Keinosuke Nagai
Published: October 2002

In this work, we propose a new method of sonic field measurement using light waves. The advantage of using light is to be able to measure sonic fields without contact. The main conventional method involving use of light is sound pressure intensity measurement using optical diffraction of sonic fields. On the other hand, the new method can be used to measure amplitude and phase distributions of sound pressure as a kind of wave field by means of tomography. We perform a simulation assuming a circular ultrasonic transducer. Variations of light wave phase induced by generation of sonic fields are calculated in the simulation. Using the numerical results, we reconstruct the sonic field images. It is confirmed that images of an ultrasonic field can be obtained.
Transient Fields of a Sound Source Driven by Various Wave Shape Pulses
Authors: Jitsumori Akio , Wadaka Shusou , Satoru Inoue Satoru Inoue
Published: October 2002

In recent years, linear FM wave pulses and phase modulated wave pulses have been used to improve resolution and signal to noise ratios. In this paper, we report on transient sound fields generated by a sound source which is driven by linear FM wave pulses and phase modulated wave pulses. Time varying sound pressure at a distance R from the center of a sound source is calculated, varying the angle θ from the center axis of the sound source. A new display method to represent the calculated transient sound fields is proposed. In the method, the angle θ is taken as the abscissa, the time t is taken as the ordinate, and amplitude of sound pressure is represented in color. The effectiveness of this display method is demonstrated by examining calculated results of sound fields produced by sine wave pulses and the representation of these results using the proposed method. The method allows us to observe simultaneously a time varying waveform of sound pressure at each observation point and directivity at each instant of time. Transient sound fields produced by linear FM wave pulses and phase modulated wave pulses are calculated and represented by the display method. Characteristics of these fields are discussed using the calculated and represented results.
Three Dimensional Echocardiography with a Reconstructed B-Mode Image
Authors: Osamu Oshiro Osamu Oshiro , Ayumu Matani Ayumu Matani , Kunihiro Chihara Kunihiro Chihara , Taisei Mikami Taisei Mikami , Akira Kitabatake Akira Kitabatake
Published: October 2002

This paper describes a three-dimensional (3D) dynamic heart imaging system. In this system, ultrasound B-mode images are measured with a transesophageal probe, a 3D heart image at a given phase of the cardiac cycle is reconstructed with a volume rendering technique and image processing and a 3D dynamic heart image is presented by displaying the 3D static images sequentially in the cardiac cycle. Furthermore, a 3D heart image is divided into two regions with a section, and a B-mode image is reconstructed and superimposed on that section. Experimental results indicate that the system enables us not only to observe the motion of the myocardium, the mitral valve and so on from any point of view but also to observe the inside structure of the heart in detail using the 3D image and the reconstructed B-mode image.
Influences of Trabecular Structure on Ultrasonic Wave Propagation in Bovine Cancellous Bone
Authors: Hosokawa Atsushi , Otani Takahiko , Suzaki Takuji , Kubo Yoshiomi , Takai Shinro
Published: October 2002

Ultrasonic wave propagation in water-saturated bovine cancellous (spongy) bone has been experimentally studied in vitro by a pulse transmission technique. The propagation of fast and slow longitudinal waves in bovine cancellous bone [rf:1] is examined in relation to porosity using Biot's and Wyllie's equations to estimate the measured speeds versus porosity. In the high porosity range, the trabecular structure influences the propagation of the fast and slow waves in cancellous bone.
In Situ Observation of Sintered Iron and Carbon Steel Compacts Using a Low-Temperature Acoustic Microscope
Authors: Hirose Norimitsu , Asami Junich , Sato Harumichi , Yamanaka Kazushi
Published: October 2002

Sintered iron compacts and carbon steel compacts (0.3 mass% carbon) were observed in situ using a low-temperature acoustic microscope (LTSAM). The effects of structure, pore distribution, tensile load and testing temperature were evaluated by using the acoustic images. Before the tensile test was conducted, initial inner defects, such as pores and cracks, existed in the specimens and the conditions of the defect distribution were different for each specimen. As the tensile load increased, the newly generated defect area was extended where expansion, deformation and connection of pores occurred. As the testing temperature was lowered, the area became more localized. In different structures, for example, in ferrite and in ferrite-pearlite, the trend of the acoustic images also differed, and the defect area of the latter was sharper than that of the former. These results are consistent with elongation data obtained by tensile tests and observations using an optical microscope. Therefore, the LTSAM is useful for understanding the low-temperature brittleness of sintered iron and carbon steel compacts.
Evaluation of Standard Defects Using Surface Acoustic Waves Generated by Phase Velocity Scanning of Laser Interference Fringes
Authors: Harumichi Sato Harumichi Sato , Shizuka Nakano Shizuka Nakano , Hisato Ogiso Hisato Ogiso , Kazushi Yamanaka Kazushi Yamanaka
Published: October 2002

In order to maintain the reliability of structural materials such as ceramics and micromachines, it is important to nondestructively evaluate micrometer-order surface defects that reduce the strength of these materials. Standard defects whose size and shape are precisely defined are needed but until now, only Vickers and Knoop indentation cracks were available. However, since indentation cracks are created stochastically, it is difficult to define their precise size and shape. Alternatively, we tried to make standard defects on a Si (001) wafer using the focused ion beam machining process. Four grooves of 200 µm length and 6.8, 7.8, 12.4 and 28.7 µm depth were formed by a 90-nm-diameter Ga ion beam on Si surface. We used iodine gas for making fine edges. We then tried to evaluate these defects by using the phase velocity scanning (PVS) method which generates surface acoustic waves (SAW) with excellent directivity. We used 60–110 MHz SAW generated by the PVS method and the distance from defects to probe of SAW was about 2 mm. We succeeded in detecting the scattered wave from the 6.8-µm-deep slit (d/λ∼0.08) and confirmed the usefulness of these standard defects. Next, we compared the theoretical reflection coefficient of an infinite-length crack with our experimental result and confirmed that they agree qualitatively.
Improvement in a-Si:H Properties by Inert Gas Plasma Treatment
Authors: Maruyama Eiji , Hishikawa Yoshihiro , Tanaka Makoto , Seiichi Kiyama Seiichi Kiyama , Shinya Tsuda Shinya Tsuda
Published: October 2002

Inert gas plasma treatment, using RF plasma chemical vapor deposition (CVD), has been investigated for the first time in order to improve a-Si:H properties through the modification of reactions at the growing surface. The deposition of a thin a-Si:H layer (6–150 Å) and exposure to inert gas plasma of He, Ar or Xe were repeated using RF plasma CVD at a substrate temperature of 200°C. It was found that the plasma treatment can be used to control the hydrogen content (C
H) from about 18 at.% to about 35 at.%, although it is a hydrogen-free process. Experimental results indicate that the change in the C
H of a-Si:H films is mainly determined by the decrease in the C
H of the treated a-Si:H surface and the increase in the C
H of the a-Si:H deposited on the treated surface. Furthermore, the inert gas plasma treatment probably promotes the surface reaction, which leads to a reduction of SiH2/SiH and C
H. Consequently, high-quality a-Si:H films with a wide gap (1.64 eV determined from (αhν)1/3 versus hν plots, 1.75–1.85 eV determined from Tauc's plot), low SiH2/SiH (C
H∼30 at.%, SiH2/SiH ∼0.1) and high stabilized σ ph (>10-5 Ω-1cm-1 under AM-1, 100 mW/cm2 irradiation) have been obtained by the inert gas plasma treatment method.
Photoacoustic Spectroscopy of Cu Impurities in Ceramic ZnS
Authors: Taro Toyoda Taro Toyoda , Kazuki Shinoyama Kazuki Shinoyama
Published: October 2002

Photoacoustic spectroscopy is used to study the heat generated by nonradiative processes due to Cu impurities in ceramic ZnS. It can provide information on optical absorption for ceramics because of the detection of a signal directly proportional to thermal energy induced by the absorbed photons. Photoacoustic spectra of ceramic ZnS containing Cu impurities depend on the concentration of Cu impurities. Photoacoustic signal intensities plotted semilogarithmically vary linearly with photon energy below the fundamental absorption edge. The steepness factor for ZnS which characterizes the slope in a semilogarithmic plot decreases with rising concentration of Cu impurities, indicating the structural disorder caused by the Cu impurities. The photoacoustic signal intensity for a state with a photon energy of 1.65 eV, which is considered the charge transfer transition from S2- to Cu2+, increases with rising concentration of Cu impurities concentration indicating an increase in charge transfer transitions.
Observation of Complicated Surface Defects by Photoacoustic Microscopy and Nondestructive Evaluation
Authors: Endoh Haruo , Hoshimiya Yoichiro Hiwatashi
Published: October 2002

Simulated complicated surface defects fabricated on a metal specimen are detected by photoacoustic (PA) microscopy, and their signals are reconstructed as PA images. Two types of complicated defects with slit-type cross sections were fabricated on a metal specimen by electrical discharge processing and mechanical processing. The surface defect geometry of one type is a pair of mutually parallel defects, and that of the other type is a pair of defects which cross each other orthogonally. The PA image obtained, clearly shows the locations of the edges of the two defects. Furthermore, the results show that complicated defects composed of two sections can be detected separately as individual defects, and that the photoacoustic method is useful for detection of crossing surface defects which are difficult to detect using present NDE techniques.
Brillouin Scattering from Surface Acoustic Waves in Ni/Al Multilayer Films
Authors: Hiromitsu Sato Hiromitsu Sato , Akira Yoshihara Akira Yoshihara , Akira Yamaguchi Akira Yamaguchi , Mitsuharu Shinosaka Mitsuharu Shinosaka , Kazuhiro Kameyama Kazuhiro Kameyama , Hideo Nakajima Hideo Nakajima , Hiroyasu Fujimori Hiroyasu Fujimori
Published: October 2002

The surface acoustic wave velocities in Ni/Al multilayer films were determined using Brillouin scattering for several modulation periods Λ ranging from 10.7 Å to 84.9 Å. The Rayleigh wave velocity shows a minimum around Λ∼40 Å. In order to obtain more detailed information on the elastic properties of the multilayer system, the effective elastic constants, C
11, C
33, C
44 and C
13, were determined for each multilayer. The C
13 constant increases by about 50% below Λ∼40 Å and the C
33 constant decreases slightly below Λ∼30 Å as Λ decreases. On the other hand, the C
11 constant is independent of Λ. These elastic constants effect the Rayleigh wave velocity only slightly, while the minimum of the C
44 elastic constant is a major cause of the minimum Rayleigh wave velocity.
Acoustooptic Modulator with Interdigital Transducers for Driving and Controlling on a Piezoelectric Substrate
Authors: Toda Michio Ohki
Published: October 2002

A new type of acoustooptic (AO) modulator with two interdigital transducers (IDTs) on a piezoelectric substrate and with an AO medium in contact with the substrate is fabricated and investigated. One of the IDTs is used for driving an acoustic wave in the substrate. This wave is radiated into the AO medium. The other IDT controls the reflection of the acoustic wave propagating in the substrate. The reflected wave is radiated into the AO medium, and it operates as the second wave. By changing the electrical terminal condition at the second IDT as short- or open-circuited, the diffraction pattern of the optical wave crossing the interaction region of the two radiated acoustic waves is changed to be in either `on' or `off' mode. By applying an electrical digital phase-modulated signal to the second IDT, a similar modulation of light can be achieved.
Effect of Microparticles on Acousto-Optic Diffraction in Water
Authors: Izumida Shin-ya , Kiyohiko Hayashi Kiyohiko Hayashi , Mitsunori Saito Mitsunori Saito
Published: October 2002

In Raman-Nath diffraction by microparticles in water, even-order diffraction is enhanced selectively by the suspension of microparticles. Intensities of diffracted beams increase markedly for particles larger than 10 µ m in diameter. By microscopic observation, particles 10–20 µ m in diameter align periodically at the nodes of an ultrasonic standing wave. On the other hand, particles 1–7 µ m in diameter distribute widely around the nodes. Since larger particles tend to remain at the nodes even after the ultrasonic wave is removed, even-order beams remain diffracted for several seconds.
Sound Power Reduction of Underwater Array Projector Caused by Mutual Radiation Impedance
Authors: Mikami Daiji , Yokoyama Tomoki , Akio Hasegawa Akio Hasegawa , Toshiaki Kikuchi Toshiaki Kikuchi
Published: October 2002

A sound power reduction phenomenon caused by mutual radiation impedance between underwater transducers is the basic theory applied to the underwater active acoustic control technique. The phenomenon also involves an unexpected power reduction problem of a SONAR projector, which lowers its frequency and has higher power specifications. In this paper, radiation power outputs of individual transducers are calculated from self/mutual radiation impedances, which are numerically obtained from Rayleigh's multiple integral form. The total radiation power output as a function of the phase difference angle between transducers is presented and verified by model experiments using an array projector made of piezoelectric rubber. Sound absorption and power reduction of the experimental array are visually displayed on the 3-D mapping of the measured complex acoustic intensity. Theoretical and experimental results show good agreement.
Pressure Effect of Sound Speed in the Deep Ocean
Authors: Umezawa Masaaki , Tsuchiya Toshio , Kikuchi Toshiaki , Hashimoto Akio Hasegawa
Published: October 2002

Recently, ocean acoustic tomography (OAT) has been used to investigate the phenomenon of global warming and for wide area oceanic observation. This research requires one to correctly determine the sound speed from the sea surface to the bathyal zone. The calculation of sound speed is primarily based on the equation for the speed of sound determined by Del Grosso and Chen and Millero. There are many discussions with respect to the differences between the equation for sound speed by Chen and Millero and that by Del Grosso. We measured data of temperature, salinity, pressure and sound speed from the sea surface to the bathyal zone in detail using the deep submergence vehicle, “SHINKAI 6500,” from the Japan Marine Science and Technology Center (JAMSTEC). From our measurements, the constant term of the gradient of sound speed from the measured data agrees with that of the equation derived by Chen and Millero, while the first and the second terms of the gradient of sound speed from the measured data agree with that of the equation by Del Grosso.
Experiments on Discrimination between the Same Materials of Different Grain Size
Authors: Kitami Mitsumasa , Ogawa Kiyoma , Nobuyuki Takano Nobuyuki Takano , Seiichi Motooka Seiichi Motooka
Published: October 2002

The authors devised a method to discriminate water bottom materials using the pulse echo method and multilayered neural network data processing. Using this method, experiments to investigate the discrimination ratio were carried out using crushed stones and sea sand in a water bath. In the case of crushed stones, the change in discrimination ratio due to the change in size of crushed stones was studied. For sea sand with small grain size relative to the wavelength, the change in the discrimination ratio relative to specific acoustic impedance was studied. As the result of the experiments, a discrimination ratio of 70–80% was achieved when the size of crushed stones was different by approximately one wavelength, and there was a difference of 12000 ( g/cm2·s) in impedance for sea sand.
Coupling Characteristics between Geophone and Ground Model
Authors: Kimura Masao , Hidekazu Watanabe Hidekazu Watanabe , Sayuri Kawashima Sayuri Kawashima
Published: October 2002

In this study, the coupling characteristics between a geophone and three kinds of ground models are measured, and the results of resonant frequency and damping factor measurements are investigated. In particular, the shear wave velocities calculated from the equation, which relates the resonant frequency of the coupling to the shear wave velcoity in ground models, is compared with the measured shear wave velocities.
Surface Treatment of Indium-Tin-Oxide Substrates and Its Effects on Initial Nucleation Processes of Diamine Films
Authors: Shizuo Fujita Shizuo Fujita , Takeshi Sakamoto Takeshi Sakamoto , Kentaro Ueda Kentaro Ueda , Kazuki Ohta Kazuki Ohta , Shigeo Fujita Shigeo Fujita
Published: October 2002

The effects of several surface treatment techniques for indium-tin-oxide (ITO) substrates on the surface properties and the initial nucleation processes of trisphenyldiamine (TPD) have been investigated. Mechanical rubbing, HCl treatment, and O2-plasma irradiation smoothen the ITO surface and enhance the cohesion of TPD molecules. As-received ITO surfaces promote amorphous structure of the TPD molecules; this results in effective carrier transport, but the substrate surface is too rough on a molecular scale for the fabrication of very thin ( e.g., ≤200 Å) layered structures. Layer-by-layer amorphous nucleation on flat surfaces is a key technology for the fabrication of future organic electroluminescence (EL) device structures with very thin constituent layers. O2-plasma treatment reduces the potential barrier for hole injection from ITO to TPD with moderate cohesion of TPD molecules, and results in brighter EL devices than those on as-received ITO substrates.
Iodine-stabilized 633-nm He–Ne Laser for Long-baseline Interferometers
Authors: Akito Araya Akito Araya
Published: October 2002

An internal-mirror He–Ne laser (λ=633 nm) was frequency stabilized to a hyperfine component of iodine transitions. The absorption signal and its derivative were obtained by the modulation transfer technique with both amplitude- and frequency-modulated pump beams. These modulations were realized using an acousto-optic modulator (AOM), without modulating the laser resonator. Owing to this external frequency modulation, the stabilized output, which is free from frequency modulation, can be used in long-baseline interferometers, such as geophysical laser strainmeters.
Dependence on Ce Concentration of Blue Emission and Crystallographic Properties in SrGa2S4:Ce Electroluminescent Thin Films Grown by Molecular Beam Epitaxy
Authors: Tanaka Katsu , Inoue Yoji , Okamoto Shinji , Kikuo Kobayashi Kikuo Kobayashi , Kuniharu Takizawa Kuniharu Takizawa
Published: October 2002

The Ce-doping dependence of blue emission properties has been investigated for SrGa2S4:Ce electroluminescent (EL) thin films grown by molecular beam epitaxy (MBE). EL spectra, EL luminance, photoluminescence (PL) spectra, X-ray diffraction (XRD) intensity, XRD rocking curves, spacing of lattice planes, EL and PL decay times were measured in samples with Ce-doping concentrations ranging from 0.87 mol% to 8.37 mol%. EL luminance reached a maximum at 2.40 mol%. In particular, EL chromaticity remained within the pure blue region even with higher Ce-doping concentrations.
Characteristics of Pyroelectric Infrared Array Detector Made of PbTiO3 Ceramics
Authors: Hashimoto Kazuhiko , Tsuruta Tomohiro , Nishimura Koji , Morinaka Katsuya , Mariko Kawaguri Mariko Kawaguri , Nobuyuki Yoshiike Nobuyuki Yoshiike
Published: October 2002

A one-dimensional pyroelectric array detector as a multi-element infrared sensor has been developed by using a new sheet forming method made of PbTiO3 bulk ceramics. This simple fabrication process is cost effective and enables us to control the film thickness accurately, thus decreasing the sensitivity variations that exist in one detector and among different detectors to within 10%. A pyroelectric detector responsivity of 2×104 V/W can be obtained at 10 Hz chopping frequency. A specific detectivity D
* of 0.8×108 cm· Hz1/2/W has been achieved. Furthermore, this detector has a sufficient sensitivity for performances at high chopping speeds up to 100 Hz. The time constant of this pyroelectric detector is about 8.6 ms, so the detector has a shorter response time compared with the commercially available conventional pyroelectric detector. The cross talk, which influences the output for the adjacent elements, is less than 10%. By using this high performance pyroelectric array detector, the thermal sources at lower temperatures than environmental conditions can be detected with high sensitivity, as much as the thermal sources at higher temperatures. The output voltage for the detector was gradually decreased as the atmospheric temperature increased.
Ba0.3Sr0.7TiO3 Thin Film Production on Atomically Flat SrTiO3 (100) Substrates by a Pulsed Laser Deposition and Dielectric Properties
Authors: Nakano Mitsuru , Tabata Hitoshi , Katayama Yûzô , Kawai Tomoji
Published: October 2002

Atomically flat SrTiO3 (100) substrates have been obtained using annealing treatments at 1000° C in O2 flow. Ba0.3Sr0.7TiO3 (BSTO) films have been produced on these substrates using a pulsed laser deposition. Film thickness dependence on the dielectric constants of the BSTO films are examined in this study. The BSTO films produced on these atomically flat SrTiO3 substrates showed higher dielectric constants than those formed on the commercially supplied SrTiO3 substrates. It is considered that this phenomenon is caused by the stresses of the mismatch between the films and substrates. The interface flatness between the films and substrates is measured by transmission electron microscopy (TEM) which is desirable for the production of dielectric films.
Control and Modification of Nematic Liquid Crystal Pretilt Angles on Polyimides
Authors: Lee Kang-Wook , Lien Alan , Paek James H. Stathis
Published: October 2002

The pretilt angle (Θ p) of nematic liquid crystals (LCs) could be controlled with alignment layer (AL) polyimides (PIs) and/or LCD processes in the case that a cell gap and a rubbing condition are fixed. Θ p was increased by introducing long, linear alkyl side chains and/or other nonpolar groups to the AL polyimide. On the other hand, Θ p was decreased by modifying the polyimide surfaces (with UV exposure or O2 plasma) and LCD processes such as heating or cleaning the rubbed polyimide and annealing the LC-filled cell. Thus, the AL polyimide and the LCD process can be designed so as to obtain a desired pretilt angle, which is important in applications. In the UV-type two-domain twisted nematic approach for wide-viewing angle LCDs, two different Θ ps were obtained in one pixel and a mechanism for modifying the Θ p was discovered. Upon UV-exposing the PI films, aromatic or conjugated radicals with long lifetimes (greater than 2 weeks) were generated and some side chains were removed, and these PI surfaces subsequently became more polar since polar functional groups such as OH were introduced. The Θ p of ZLI-5080 on the UV-exposed/rubbed PI film decreased by 4.5°–8.8° in comparison with that on the rubbed film probably because the lower steric repulsion and greater electronic attraction would decrease the Θ p.
Observation of Ferroelectric Polarization in the Noncontact Mode of a Scanning Nonlinear Dielectric Microscope
Authors: Yasuo Cho Yasuo Cho , Akio Kirihara Akio Kirihara , Takahiro Saeki Takahiro Saeki
Published: October 2002

This paper describes the performance of a scanning nonlinear dielectric microscope when a gap exists between the specimen and the probe of the microscope. First, a theory for the sensitivity of the scanning nonlinear dielectric microscope as a function of the gap height is described. Second, using the microscope in a noncontact mode, an area scan of the polarization of an alternately poled ferroelectric thin film of a copolymer consisting of vinylidene fluoride and trifluoroethylene is carried out.
Ion Assisted Deposition of Crystalline TiNi Thin Films by Electron Cyclotron Resonance Plasma Enhanced Sputtering
Authors: Martin Mišina Martin Mišina , Yuichi Setsuhara Yuichi Setsuhara , Shoji Miyake Shoji Miyake
Published: October 2002

Electron-cyclotron-resonance plasma enhanced sputtering with magnetic-mirror plasma confinement is characterized by low working pressures and large ion flux densities. TiNi thin films were deposited by this technique onto preheated Si (111) substrates. The crystal structure and composition of the films were analyzed by X-ray diffraction and Rutherford backscattering spectrometry, respectively. The substrate temperature T
cr necessary for deposition of crystalline TiNi films was determined as a function of the ion-to-metal flux ratio j
ion/j
Ti+Ni and ion energy E
i. T
cr as low as 555 K was found for j
ion/j
Ti+Ni=3.9 and E
i=150 eV. Substrate temperatures higher than T
cr resulted in a textured crystal structure. Factors affecting the composition of the deposited thin films are also discussed.
An X-Ray Diffraction Study on the Transition of Micro Structural Defect States with the Interchange of Solvent and Solute in Ti–Zr and Zr–Ti Alloys
Authors: Sen R. , Chattopadhyay S. K. , Chatterjee S. K.
Published: October 2002

Detailed Fourier line shape analyses have been performed considering some fault affected and fault unaffected reflections in two hexagonal systems of alloys namely Ti base Zr alloys and Zr base Ti alloys having different compositions. It has been observed that while Ti base Zr alloys show marked increase in deformation fault parameters with zirconium concentration, zirconium on the other hand is not prone to faulting as solvent with the addition of titanium as solute.
Effects of O 2/Ar Ratio and Annealing on the Properties of (Ba,Sr)TiO 3 Films Prepared by RF Magnetron Sputtering
Authors: Lee Joon , Choi Young-Chul , Lee Byung-Soo
Published: October 2002

Perovskite-structure (Ba,Sr)TiO3 (BST) thin films were prepared on Pt/SiO2/Si substrates by RF magnetron sputtering with various O2/Ar ratios and subsequent annealing. The crystallinity and electrical properties of the films were investigated. It was demonstrated that the electrical properties, such as leakage current and capacitance, of the films depend strongly on the oxygen content of the sputtering gas. With increasing oxygen content of the sputtering gas, the leakage current decreases and the capacitance increases. Both the dielectric constant and the leakage current density increase upon annealing. It is believed that the electrical properties of BST films depend strongly on the grain size and surface roughness of the films.
Fabrication of SiO2/Si/SiO2 Double Barrier Diodes using Two-Dimensional Si Structures
Authors: Namatsu Hideo , Horiguchi Seiji , Takahashi Yasuo , Masao Nagase Masao Nagase , Kenji Kurihara Kenji Kurihara
Published: October 2002

In this article, we demonstrate a technique for fabricating SiO2/two-dimensional (2D)-Si/SiO2 double barrier diodes and discuss their characteristics. Vertical 2D-Si with {111} side planes is formed by orientation-dependent etching of {110} Si using aqueous alkaline solution. The linewidth of the 2D-Si is reduced to nanometer order with NH4F/H2O2 solution. This solution also removes the residue generated on Si planes etched by aqueous alkaline solution. Using a skillful arrangement of dummy patterns and an etchback technique, poly-Si electrodes are successfully formed without any lithographic alignments. A SiO2/2D-Si/SiO2 diode fabricated by this process shows resonant characteristics that are in agreement with the calculated values.
Effect of Molecular Structure of Substituents on Green Electroluminescence in Disubstituted Acetylene Polymers
Authors: Rahmat Hidayat Rahmat Hidayat , Masaharu Hirohata Masaharu Hirohata , Kazuya Tada Kazuya Tada , Masahiro Teraguchi Masahiro Teraguchi , Toshio Masuda Toshio Masuda , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Intense green photoluminescence (PL) in the wavelength range of 520 to 540 nm was observed in many poly(diphenylacetylene) (PDPA) derivatives. The band gap energy and the highest occupied molecular orbital (HOMO) energy of these polymers were estimated to range from 2.6 to 2.7 eV and -5.6 to -5.9 eV depending on the substituent. Green electroluminescence (EL) was observed from EL devices fabricated utilizing these polymers. Among these PDPA derivatives, poly(1-phenyl-2-m-(trimethylsilyl)phenylacetylene) (PDPA-mSiMe3) with the smallest band gap energy exhibited the weakest PL and EL of longest wavelength. Polymers with bulkier and/or longer substituents exhibited stronger PL and EL. The results are interpreted in terms of a steric hindrance effect and the interchain interaction depending on the molecular structure of the substituents. In addition, upon electrochemical doping, these light emissive polyacetylene derivatives exhibited evolution of new single midgap absorption suggesting formation of solitons.
A Model for Resolution Dependent Roughness Values Measured by an Optical Profiler for Specific Surfaces
Authors: Furukawa Masakazu , Shingubara Shoso , Horiike Yasuhiro
Published: October 2002

The rms roughness value obtained using an optical profiler depends on the horizontal resolution which is determined mainly by the objective magnification, especially when the surface grain or peak diameters are less than the resolution. A model is proposed to determine the dependency of the rms roughness value on the resolution. The optical height in an area of horizontal resolution is defined the an average of the surface profiles. A large area inspected by a small magnification (SX) objective is adjusted to R
2-times the size of small areas inspected by a large magnification (LX) objective, where R
2 is the ratio of a large cell area defined by the horizontal resolution of the SX objective to a small cell area defined by a horizontal resolution of the LX objective. It is shown that the ratio of the rms roughness value in the small area to that in the large area is equal to R, since the optical height of a grain in the small cell area is R
2-times as large as that in the large cell area. The calculated value from the present model agrees with the average of experimental results.
Fine Imaging Scanning Electron Microscope due to Secondary Electron Multiplication and Optical Configuration
Authors: Tanno Usaburo Eguchi
Published: October 2002

We demonstrated that immediate multiplication of two-dimensional secondary electrons from a specimen and use of optical configuration provided a fine imaging scanning electron microscope yielding both low acceleration voltage and fine observation. The multiplied secondary electrons give rise to a very bright fluorescence intensity distribution due to the collision with the fluorescence-painted glass plate. Just it's center part was optically extracted using an aperture and detected by a photomultiplier. As a result, the pixel signal of the observed image achieved the highest signal-to-noise ratio. The observed image, therefore, had higher resolution and broader dynamic range. This novel method can be used to perform a fine microstructure observations of materials, using real low 1000 V primary electron acceleration.
Impurity-Doped GaSe Radiation Detector Evaluated at 100°C
Authors: Yamazaki Toshinari , Terayama Kiyoshi , Shimazaki Toshiharu , Hideo Nakatani Hideo Nakatani
Published: October 2002

The pulse height distribution for 5.5 MeV α particles from 241Am was measured using a GaSe detector doped with 0.1 at.% Sn at 100°C and compared with that measured at room temperature. It was found that the energy resolution at 100°C was 8.3% which was as good as that at room temperature. The temperature dependence of the leakage current of the detector was also measured for the applied voltage of 50 V and found to have a small value of 60 nA at 100°C.
Theory of Transport Through a Single Atomic Junction
Authors: Fumiko Yamaguchi Fumiko Yamaguchi , Dehuan Huang Dehuan Huang , Yoshihisa Yamamoto Yoshihisa Yamamoto
Published: October 2002

A theory of transport properties through a single atomic junction consisting of a single atom and two electrodes is presented. Such an atomic junction is realized with a system of a scanning tunneling microscope (STM) tip, a single atom located at the tip apex and a sample surface. Electron tunneling between an atom and an electrode through a vacuum potential barrier is governed simultaneously by the Coulomb potential (Coulomb blockade effect) and Pauli exclusion principle due to an atomic discrete energy spectrum. Measurement of conductance oscillation due to the Coulomb blockade effect and Pauli principle in such a system allows one to determine the highest occupied energy level and its degeneracy of the atom as well as the local work function of the tip apex and the band gap of the sample surface.
Scanning Tunneling Microscopy/Spectroscopy Study of Self-Organized Quantum Dot Structures Formed in GaP/InP Short-Period Superlattices
Authors: Noh Joo-Hyong , Asahi Hajime , Seong-Jin Kim Seong-Jin Kim , Shun-ichi Gonda Shun-ichi Gonda
Published: October 2002

Self-organized quantum dot (QD) structures formed in (GaP)

n

(InP)

m

short-period superlattices (SLs) grown on GaAs (N11) substrates by gas source MBE (molecular beam epitaxy) are studied by scanning tunneling microscopy (STM)/scanning tunneling spectroscopy (STS). STM images show high density QD structures as bright areas. The dot size of these structures ranges from 15 nm to 25 nm with a dispersion of ±10% depending on the n and m of the SLs. In the STS measurement, the voltage width for dI/ dV=0 varies along the lateral direction on the sample surface. This voltage width variation corresponds to the lateral variation of the band-gap energy and of the tunneling probability by the lateral composition modulation.
Nanoscale Patterning and Selective Growth of GaAs Surfaces by Ultra-High Vacuum Scanning Tunneling Microscopy
Authors: Makoto Kasu Makoto Kasu , Toshiki Makimoto Toshiki Makimoto , Naoki Kobayashi Naoki Kobayashi
Published: October 2002

After amorphous-like N-passivated GaAs surfaces with a low defect density are obtained as a mask layer for selective growth, nanometer scale patterning of the surfaces is achieved using ultra-high vacuum scanning tunneling microscopy to selectively depassivate surface N atoms. After patterning, GaAs dots with well-controlled size (typically 6 nm high and 50×50 nm2) can be successfully grown using trimethylgallium and tertiarybutylarsine in the specific area where the underlying GaAs layer appeared.
Nanorheology of Polymer Blends Investigated by Atomic Force Microscopy
Authors: Ken Nakajima Ken Nakajima , Hideki Yamaguchi Hideki Yamaguchi , Jeong-Chang Lee Jeong-Chang Lee , Masami Kageshima Masami Kageshima , Takayuki Ikehara Takayuki Ikehara , Toshio Nishi Toshio Nishi
Published: October 2002

We measured force–distance curves of polystyrene (PS)/poly (vinyl methyl ether) (PVME) blend thin films using atomic force microscopy (AFM) in order to pursue the possible usage of AFM as a tool for detecting viscoelastic properties of polymeric materials from a nanoscopic point of view. In quasi-static measurements of force–distance curves for a sample whose PS content equals 100%, both adhesive force and capillary force were measured separately. A phenomenon possibly assigned to pulling off of polymer chains by an AFM tip could also be observed for a sample whose PS content equals 60%. By changing the velocity of the AFM tip acting on a blend sample whose PS content equals 40%, we confirmed that the law of time–temperature reducibility holds even on such a nanoscopic scale. This blend sample behaved as a viscous fluid at room temperature, while its behavior became glassy when faster movements of the AFM tip were applied. A discussion on the future development of a new field of research which should be called “nanorheology" was also presented.
Protein Stretching II*1: Results for Carbonic Anhydrase
Authors: Ping Wong Atsushi Ikai
Published: October 2002

The force curve measurement mode of an atomic force microscope was used to record the force required to stretch a protein molecule that was covalently sandwiched through gold-thiol bonds between a mica substrate and a silicon nitride tip, both coated with gold. In one experiment, 8 ±1 out of 20 lysyl residues of bovine carbonic anhydrase B were randomly derivatized to give free thiols, and grafted on an atomically flat gold (111) surface on mica. Force curves taken on the surface covered with protein molecules using a gold coated tip occasionally showed a large downward deflection indicating trapping and subsequent stretching of protein molecules between the tip and the substrate. In another experiment, the same protein was genetically engineered so that cysteine residues were introduced at both the amino and the carboxyl terminus. Force curves taken in a similar manner as in the first experiment indicated almost complete extension of a linear polypeptide chain. The result was explained in terms of extension of a pseudo-three-dimensional gel in both cases, with additional stretching of a linear chain in the second case.