bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Cyclotron Resonance Ion Source for Ion Thruster
Authors: Satori Shin , Nishiyama Kazutaka , Hitoshi Kuninaka Hitoshi Kuninaka , Kyoichi Kuriki Kyoichi Kuriki
Published: October 2002

An electron cyclotron resonance (ECR) ion source was designed and its performance was studied in comparison with a DC ion source. Ion production cost of 340 V/ion for ECR ion source and 189 V/ion for DC ion source were obtained at the pressure of 0.5 mTorr and the discharge power of 50 W. A luminosity distribution of the Ar-II line was imaged through an interferometer filter and a luminous arch hill was observed near the ECR region, where the plasma was resonantly generated. Ion wall loss measurement showed that the ion production cost became worse due to the excessive ion wall loss near the cusped magnets, where the plasma confinement was inferior to that of the DC ion source.
Perpendicular Magnetic Anisotropy of Metallic Multilayers Composed of Magnetic Layers Only: Ni/Co and Ni/Fe Multilayers
Authors: Kyuno Kentaro , Ha Jae-Geun , Asano Ryoichi Yamamoto
Published: October 2002

The magnetic anisotropy energies of multilayers which include only magnetic elements, Ni/Co and Ni/Fe, are calculated from first principles. Both systems show perpendicular anisotropy but the anisotropy energy is somewhat smaller than that of well-studied systems such as Pd/Co. The LDOS (local density of states) of Ni is as large as that of Co(Fe) at the Fermi level and contributes directly to perpendicular anisotropy, which means that the magnetic moments of Ni are also normal to the film plane. The anisotropy cannot be explained only in terms of the electronic structure of Co(Fe) near the Fermi level but that of Ni must also be considered. The origin of the perpendicular anisotropy is attributed to a large LDOS of |m| =2 character of Co(Fe) and Ni minority spin near the Fermi energy.
Electron Cyclotron Wave Plasma Production Using a Concave Lens
Authors: Masaya Sugimoto Masaya Sugimoto , Masayoshi Tanaka Masayoshi Tanaka , Yoshinobu Kawai Yoshinobu Kawai
Published: October 2002

A plasma production experiment was performed using a microwave concave lens. A large-wave-number electron cyclotron wave is excited efficiently with the lens, and exhibits fast damping. For 5 kW input power, in low-pressure operation, the electron temperature is 70% higher than that without the lens, while in high-pressure operation, the electron density is 40% higher than that without the lens.
Molecular Orientation of all-trans-β-Carotene in Spin-Coated Film and in Langmuir-Blodgett Film as Detected by Polarized Optical Absorption and Reflection Spectroscopies
Authors: Hashimoto Hideki , Kiyohara Dai , Kamo Yoshitaka , Hiroshi Komuta Hiroshi Komuta , Yuzo Mori Yuzo Mori
Published: October 2002

The molecular orientation and spatial arrangement of all- trans-β-carotene in a spin-coated (SC) film and in a mixed Langmuir-Blodgett (LB) film with barium stearate (1:10) were studied by the use of polarized optical absorption and reflection spectroscopies at non-normal incidences. The newly applied analyses of these spectra show that the SC film is an amorphous film with density ρ=0.835 g/cm3, refractive index n=1.38 and extinction coefficient κ=1.09 at 445 nm. Based on the axis model proposed by Schmidt and Reich [Ber. Bunsenges. Phys. Chem. 76 (1972) 1202], the angle of the molecular axis in the LB film relative to the plane of the substrate was determined to be 27°. The relative strengths of the molecular interaction of β-carotene were compared for the n-hexane solution, LB film, SC film, and single crystal. It was shown that the molecules in the LB film are weakly aggregated, although the size of the aggregate is so small that it can be identified as a `monomer'. The Davydov splitting E
D of the single crystal is obtained as 170±60 cm-1.
Study of Microwave Transient Photo Conductivity on Single and Polysilicon Using Cavity Perturbation Technique
Authors: V. Subramanian V. Subramanian , J. Sobhanadri J. Sobhanadri
Published: October 2002

Microwave cavity perturbation technique has been employed for the study of photo conductive transients in semiconductors. A new approach of measuring the quality factor of the microwave cavity using cavity perturbation technique (reported in Rev. Sci. Instrum. 65 (1994) 453] is incorporated for this purpose. Measurements with this contactless technique on carrier lifetimes in various single and polysilicon and the analysis of the observed microwave transient photo conductivity decay with temperature is reported.
Quick Measurement of Brillouin Spectra of Glass-Forming Material Trimethylene Glycol by Angular Dispersion-Type Fabry-Perot Interferometer System
Authors: Itoh Shin-ichi , Kojima Takashi Yamana
Published: October 2002

Brillouin scattering of Trimethylene Glycol which often crystallizes on slow cooling was measured from 197 K to 426 K using the angular dispersion-type Fabry-Perot interferometer with a CCD detector. Especially the Brillouin spectra on the cooling from 300 K to 197 K could be observed only in 1.5 h without crystallization. The observed sound velocity and anomalous attenuation are analyzed by a single relaxation model. The relaxation frequency obeys the Arrhenius law with an activation energy of 3.71 kcal/mol. This suggests that the observed sound anomaly is due to the fast β-relaxation process.
Study of New Technique for Three Dimensional Images in Photoacoustic Microscope
Authors: Yoshiaki Tokunaga Yoshiaki Tokunaga , Keimei Tamura Keimei Tamura
Published: October 2002

We developed a technique for simultaneous measurement of multiple frequencies that allows rapid image build-up. The elapsed time required for measurement of the ω-1 dependence of the photoacoustic signal in the frequency range of 10 to 100 Hz in a graphite was 1/5 that required for a conventional technique employing a lock-in amplifier.
Impurity Effect on Recombination Processes in InP
Authors: Yoshinaga Hiroshi , Uehara Tokue Matsumori
Published: October 2002

The effects of impurities (S, Sn, Fe and Zn) doped in InP on recombination processes were investigated using photoluminescence (PL) and photoacoustic (PA) spectroscopies. The recombination processes were affected by the impurity levels in the bandgap and by the large strain which was induced by the impurities in InP. The processes were radiative for InP with shallow impurity levels such as S-doped and Sn-doped samples and nonradiative for InP with deep impurity levels such as Fe-doped and Zn-doped samples. The results of PL and PA measurements were in a reciprocal correlation. However, both spectra were observed for undoped InP with large strain induced by impurities such as Si. These relationships were explained using three types of configuration coordinate diagram.
Sound Propagation Characteristics in Sound Fixing and Ranging Channel across Geostrophic Current
Authors: Endoh Nobuyuki , Morita Koji , Enami Homare , Shojiro Sato Shojiro Sato , Takenobu Tsuchiya Takenobu Tsuchiya
Published: October 2002

In order to develop ocean acoustic tomography techniques, it is very important to determine optimal receiving points and the propagation characteristics of sound in the SOFAR (SOund Fixing and Ranging) channel. We describe a preliminary computer simulation to estimate the sound arriving through a SOFAR channel across a geostrophic current. It is assumed that an ocean current is a geostrophic current and crosses the 1200 km propagation path at its center. Propagation times and detected pulsed sound waveforms are obtained in both directions of north-south propagation when the maximum flow speed changes from 0 to 153 cm/s. It is shown that a geostrophic current affects the propagation characteristics of sound. The difference in the propagation times for both directions can be used to estimate the flow speed along the propagation path.
Acoustic Wave Devices Using Artificial Twin Quartz Plates
Authors: Takehiko Uno Takehiko Uno
Published: October 2002

We present a technique to form an artificial twin quartz plate with an arbitrary pattern. After depositing a thin metal film of chromium, nickel or Nichrome on a quartz plate, the substrate is thermally treated. Thermal treatment at 550–560° C causes x-axis inversion for the quartz under the film while the x-axis inversion does not occur in other areas. The x-axis inversion phenomenon depends on the cut angle of the substrate, film material and film thickness. Applications of the x-axis inversion phenomenon to bulk acoustic wave devices are proposed. One is the configuration of an AT-cut resonator with a temperature sensor on chip. The other is the temperature compensation technique for AT-cut resonators. Experimental results suggest the possibility for these applications.
Improvement of the Pumping Efficiency in an Optically Pumped Cesium Beam Tube with a (σ + π)-Polarized Laser
Authors: Ho Seong Lee Ho Seong Lee , Sung Hoon Yang Sung Hoon Yang , Young Bum Kim Young Bum Kim , Jin Ok Kim Jin Ok Kim , Cha Hwan Oh Cha Hwan Oh
Published: October 2002

We observed that atomic population was trapped in the ground state of cesium atoms when a σ-polarized laser was illuminated to the atoms under a weak static magnetic field in an optically pumped cesium beam tube. The population trapping could be removed by applying a (σ+π)-polarized laser which was made by superposition of both σ- and π-polarizations. The pumping laser with the (σ+π)-polarization increased the pumping efficiency even in the low magnetic field and accordingly, the background noise of the Ramsey spectrum was reduced by about four times and moreover, the Ramsey signal became more stable against the power fluctuation of the pumping laser.
Characteristics of Bleustein-Gulyaev-Shimizu Wave Resonators on Ceramics at High Frequencies
Authors: Kazuhiko Morozumi Kazuhiko Morozumi , Michio Kadota Michio Kadota , Seigo Hayashi Seigo Hayashi
Published: October 2002

At frequencies above 60 MHz , tuning-free surface acoustic wave (SAW) resonators with many reflectors using Rayleigh SAW are generally used. However, Rayleigh SAW resonators for use in the 60–150 MHz range have some disadvantages such as cost. We have already developed a BGS wave resonator, which is being used commercially in the 30–60 MHz range. When we improved the characteristics of BGS wave resonators by using small-particle , poreless ceramic substrates developed for high-frequency BGS waves, we obtained good resonance characteristics up to 160 MHz. We also obtained good characteristics when we tested the resonator in a DECT demodulator circuit.
10 GHz Surface Acoustic Wave Filters with Narrow-Gap Interdigital Transducer Structure
Authors: Kazuhiko Yamanouchi Kazuhiko Yamanouchi , Kazuo Aoki Kazuo Aoki , Takatoshi Tsuji Takatoshi Tsuji , Yasuo Wagatsuma Yasuo Wagatsuma
Published: October 2002

Controllable well-insulated gaps between electrodes can be obtained by anodic oxidation of the edges of the regions of an Al film covered by photo resist. This technique is used to fabricate surface acoustic wave narrow gap interdigital transducers (NG-IDTs) and narrow gap floating electrode type unidirectional transducers (NG-FEUDTs). Experimental results indicate that the SAW NG-IDTs and NG-FEUDTs operate in the 10GHz range and have an electrode width of less than 0.2 µm.
Analysis of Leaky Surface Acoustic Waves Propagating on Piezoelectric Substrates of Finite Thickness
Authors: Shigetaka Tonami Shigetaka Tonami , Atsuhiro Nishikata Atsuhiro Nishikata , Yasutaka Shimizu Yasutaka Shimizu
Published: October 2002

A numerical analysis of the propagation characteristics of leaky surface acoustic waves is presented, taking into account the finite thickness of piezoelectric substrates. In the analysis, all the 8 plane waves in the substrate are superposed to fulfill the boundary conditions on both surfaces of the substrate. The computational result for LST-cut quartz substrate shows that a first leaky wave splits into even and odd modes when the thickness is reduced. In contrast, the computational result for (90°, 90°, 31°)-cut LiTaO3 substrate shows that many propagation modes exist depending on the substrate thickness, where each velocity approaches that of the longitudinal wave for smaller thickness.
Residuals Caused by the CF4 Gas Plasma Etching Process
Authors: Komine Kenji , Araki Nobusige , Noge Satoru , Ueno Hiroki , Hohkawa Kohji
Published: October 2002

We investigate residual polymers caused by the CF4 plasma etching trimming process on narrow-bandwidth surface acoustic wave devices. In order to stabilize frequencies of the trimmed devices against water vapor, residuals were analyzed both physically and chemically. The residuals were composed of carbon and fluorine, and the frequency shift was caused by the reaction of residuals with water vapor. A post-trimming process such as exposure to O2 plasma or heat treatment in vacuum was used in order to remove or to stabilize the residuals. The experimental results showed no frequency shift after the post-trimming process, and heat treatment in vacuum was found to be an effective method for inactivating residuals.
Surface Acoustic Wave Semiconductor Coupled Devices Employing Epitaxial Lift-Off Films
Authors: Hohkawa Kohji , Suzuki Hiroji , Komine Kenji , Qixin Huang Qixin Huang
Published: October 2002

We present high-performance surface acoustic wave semiconductor coupled devices in which highly functional compound semiconductor devices and highly efficient surface acoustic wave devices are monolithically integrated on the same substrate using epitaxial lift-off films. We investigated the optimal conditions for lift-off and bonding processes and succeeded in fabricating a quasi-monolithic structure without any damage in semiconductor films. We also investigated basic integrated circuit fabrication processes such as patterning and etching of the quasi-monolithic substrate. The bonded film is stable and rugged enough against these processes and the substrate can be handled as a monolithic substrate. Based on our experimental results, we confirmed that fabricating high performance functional devices is feasible.
A Bleustein-Gulyaev-Shimizu Wave Resonator with 2 or 3 Resonances for Double Traps in TV and VCR (VTR)
Authors: Michio Kadota Michio Kadota , Junya Ago Junya Ago , Hideya Horiuchi Hideya Horiuchi
Published: October 2002

A Bleustein-Gulyaev-Shimizu (BGS) wave with only a shear-horizontal (SH) displacement has the property of complete reflection at the free edge of a piezoelectric ceramic substrate. A BGS wave resonator utilizing this property is super-miniature and wide band, has a small capacitance ratio, and does not require frequency tuning. At present, two kinds of BGS resonators have been used as the additional traps at f
ap and f
as in TV·VCR VIF circuits. In this work, utilizing the responses generated due to the frequency characteristic of weighted IDT and even mode reflections at free edges of the substrate, we propose a new type of BGS resonator device which has two or three resonant frequencies for both f
ap and f
as. By applying this resonator in a VIF circuit, we have confirmed that it produces sufficient attenuations for practical use at both f
ap and f
as.
Low Insertion Loss Surface Acoustic Wave Matched Filter with Low Sidelobe Sequence and Its Application for Spread Spectrum Communication
Authors: Shiba Takashi , Yuhara Akitsuna , Moteki Minoru , Ota Yasuhiro , Tamizu Kazuhide , Okajima Daini , Oda Kouji , Tsubouchi Kazuo
Published: October 2002

For direct sequence (DS) spread spectrum communication systems with differential phase-shift keying (DPSK) modulation, we have calculated low autocorrelation sidelobe pseudo noise (PN) sequences. We constructed a matched filter comprising localized layered structure on a quartz crystal to obtain low matching loss. As a result of the sequences and the construction, 14 dB (6 dB improvement on that of the conventional sequences) peak vs sidelobe of correlated output signal and 9 dB lower loss than that of a conventional filter was achieved. We have applied these matched filters to SS rf-modem units for weak-power digital communications. In these modem units high data rate (1 Mbps), long communication distance (about 20 m) and low current (210 mA when received) performances are obtained.
Simple Multipurpose Cryostat for Experiments Using High Magnetic Field
Authors: Kazu Nishigaki Kazu Nishigaki , Minoru Takeda Minoru Takeda
Published: October 2002

In order to study the effect of the strong magnetic field of liquid oxygen, we constructed a simple cryostat in which a split-type superconducting magnet is incorporated. The structure and operation of the cryostat are simple, and direct observation of specimens under strong magnetic field is easy. The maximum magnetic field strength of the system is 7 T, and the space available for experiments is approximately 50 mmφ×100 mm. Furthermore, since the range of temperatures for experiments is broad, between 2 K and 300 K, the system is suitable for the study of the effects of strong magnetic field on the characteristics of the interface, and on pattern formation in systems not only in cryofluids but also in other materials.
Ultrasonic Transducer Array for Structural Intensity Measurements
Authors: Ryusuke Morikawa Ryusuke Morikawa , Hidetoshi Yuzaki Hidetoshi Yuzaki , Kentaro Nakamura Kentaro Nakamura , Sadayuki Ueha Sadayuki Ueha
Published: October 2002

Measurement of structural intensity, which is a vector quantity defined as an energy flow of vibration per unit area and is calculated from vibration velocity distribution, is a key technique for radiation noise reduction and vibration control. An ultrasonic Doppler vibrometer array is proposed for structural intensity measurement. A useful large array probe can be constructed. Since the ultrasonic system is much cheaper than an optical one, and has no loading effect on specimens during measurement, in constant with conventional methods that use an accelerometer and a strain gauge, a system for 1-dimensional measurements is made which is composed of ultrasonic transducers and an FM demodulator. The validity of the proposed system is demonstrated experimentally by the 1-dimensional structural intensity measurement of a beam.
Determination of Thermal Degradation of Heated Polyvinyl Chloride using Diffracted SH Ultrasonic Waves
Authors: Fukuhara Mikio , Oguri Yoshiyuki Kuwano
Published: October 2002

Thermal degradation of polyvinyl chloride (PVC) compounds heated in air was determined by analyses of diffracted SH ultrasonic waves. Evaporation of plasticizers from PVC compounds due to thermal decomposition was evaluated by examining the the receiving wave amplitude. Thermal chain scission of PVC compounds seems to affect the increase of the integrated absolute value of wave amplitudes and the advance of phase shift with specific frequencies.
Underground Imaging Using Shear Waves: Stacking Method of the Reflected Scattered Waves
Authors: Tsuneyoshi Sugimoto Tsuneyoshi Sugimoto , Motoyoshi Okujima Motoyoshi Okujima
Published: October 2002

Electrical and electromagnetic methods are widely used to detect buried relics. However, in marshes or swamps where the moisture constant is high, these methods are difficult to use, because the electromagnetic wave is strongly attenuated by the presence of water. Although seismic prospecting utilizing elastic waves and the common depth point stacking method (CDP method), which assumes reflection at the stratum plane, are suitable for the investigation of stratigraphic structure ( e.g., at depths of 100 to 1000 m ), commercial equipment and the CDP method are not suitable for detecting relics which exist at shallow depths ( e.g., 0–10 m ). Therefore, we proposed an underground imaging method using shear waves and a method based on stacking of reflected scattered waves in which point reflection is assumed. The experimental results confirm the feasibility of our proposed method. However, the resolution of the underground image is insufficient to detect relics. Therefore, an improvement in the resolution is necessary.
Monitoring of Out-of-Plane Displacement of Hot Medium and Mechanism of Fused Silver Solder Cracking Estimated by Quantitative Acoustic Emission Source Wave Analysis
Authors: Kentaro Hayashi Kentaro Hayashi , Hiroaki Suzuki Hiroaki Suzuki , Mikio Takemoto Mikio Takemoto
Published: October 2002

This study aims to elucidate the fracture kinetics of microcracks formed during fused metal degradation of austenitic stainless steel by the acoustic emission (AE) source inversion processing. To accomplish this purpose, we developed a new heat-resistant capacitive AE sensor to measure the out-plane displacement excited by elastic waves. Wave attenuation and velocity dispersion in hot stainless steel were measured by a laser ultrasonic technique. A new source inversion processing algorithm, accounting for both the velocity dispersion and wave attenuation, was proposed. We observed a number of AE signals from Mode-I cracks during fused silver solder degradation of stressed AISI304 steel at 1000 K. The size of microcracks estimated by the source inversion processing was found to be equivalent to the size of one or two crystal grains. Crack propagation velocity reached 40 m/s and was almost 109 times that estimated by an optical microscope. It is revealed for the first time that cleavage cracks are formed rapidly during fused metal degradation.
A System for Superimposing a 3-Dimensional Stereoscopic Motion Echo Image of the Heart onto the Chest
Authors: Ayumu Matani Ayumu Matani , Yoshihiro Ban Yoshihiro Ban , Osamu Oshiro Osamu Oshiro , Kunihiro Chihara Kunihiro Chihara
Published: October 2002

In medical ultrasonic measurements, 3-dimensional reconstruction of successive B-mode images is widely used for the macroscopic observation of organs or fetuses. To understand the 3-dimensional images, a stereo display viewed with special glasses (having liquid crystal shutters) and special observation techniques (cross viewing, parallel viewing) have been previously proposed. In this paper, we proposed a system for superimposing a 3-dimensional stereoscopic motion echo image of the heart onto the chest of the subject. A see-through head-mounted display was used for merging the virtual image (3-dimensional heart image) and the real scene (the subject). By the comparing this system with previous ones, the superiority of this system was confirmed in both the resolution of the 3-dimensional heart image and the ease of observation of the image. This system allows observation of the 3-dimensional heart image within the chest of the subject as if looking into the body. In the near future, this system is expected to be beneficial to clinics for purposes such as surgical planning.
Ultrasonic Dynamical Imaging of 2-Dimensional Strain in Inhomogeneous Soft Tissue
Authors: Shin-ichi Yagi Shin-ichi Yagi
Published: October 2002

The displacement or strain at low frequency in an inhomogeneous soft tissue could be directly applied to clinical diagnosis as a dynamic visualized palpation for internal living tissues. However, for this dynamical imaging the lateral displacement on tissue cross section should be evaluated with excellent accuracy by using a conventional B-mode array transducer. By using 2-dimensional complex echo signals which are compressed to 1-bit this small displacement estimation was realized. Furthermore, by successively processing the rf echo frames that are taken at real time, dynamic imaging of 2-dimensional strain was realized.
Ultrasonic Scattering Study of Cancellous Bone for Osteoporosis Diagnosis
Authors: Kiyotaka Kitamura Kiyotaka Kitamura , Haitao Pan Haitao Pan , Sadayuki Ueha Sadayuki Ueha , Shigeo Kimura Shigeo Kimura , Naoki Ohtomo Naoki Ohtomo
Published: October 2002

Accurate diagnosis of osteoporosis requires the measurement of the thickness and interval of trabecular bones. The ultrasound signals scattered by trabecular bones are analyzed using a multilayered grating model of cancellous bone. The scattering function is derived using the model, and is proved in experiment to be effective by measuring planar stainless steel nets. The thickness and interval of trabecular bone are evaluated in the frequency domain and the spatial domain of the scattering angle. The experimentally estimated values of the thickness and intervals of trabecular bone in a cow's thigh and formalinized human heel, are approximately equal to the values measured with a mechanical scale.
Strobo-Photoelastic Visualization of Lamb Waves with Negative Group Velocity Propagating on a Glass Plate
Authors: Katsuo Negishi Katsuo Negishi , Hyo Ung Li Hyo Ung Li
Published: October 2002

An elastic wave with negative group velocity transports wave energy in the direction opposite to the phase velocity. This phenomenon has been predicted in certain modes of Lamb waves. This is still difficult to believe, despite the fact that some experimental evidence has been reported so far. In this paper, direct evidence of the negative group velocity is presented which was obtained by means of visualization of pulsed Lamb waves propagating on a glass plate in A2 mode.
Consideration of Small Variation of Surface Acoustic Wave (SAW) Velocity in Lithium Tetraborate
Authors: Ryuichi Komatsu Ryuichi Komatsu , Tamotsu Sugawara Tamotsu Sugawara , Shin Tsuchiya Shin Tsuchiya , Satoshi Uda Satoshi Uda , Kouichi Sassa Kouichi Sassa , Kazuhiko Yamanouchi Kazuhiko Yamanouchi
Published: October 2002

It has been experimentally revealed that the variation of surface acoustic wave (SAW) velocity in lithium tetraborate crystals is smaller than that in other SAW crystals. This may relate to the small deviation of lattice constant due to the little change in chemical composition of the wafer. Such homogeneity can be explained by the specific compositional properties of Li2B4O7 crystal and its melt.
Measurement of Vibration Displacement Using a Layered-Structure Leaky Wave Interdigital Transducer
Authors: Toda Kohji , Motegi Kenji , Yasuhiko Akutsu Yasuhiko Akutsu , Akihiro Sawaguchi Akihiro Sawaguchi
Published: October 2002

A technique for measuring vibration displacement using a liquid delay line is described. The delay line is composed of two pairs of layered-structure interdigital transducers (IDTs), in combination with a piezoelectric ceramic thin plate and an acryl plate, and a sound-beam-reflecting diaphragm as one wall of a liquid cavity. The IDT functions as a bulk wave radiator or a detector of a signal reflected from the diaphragm. The acoustic delay length changes linearly with the mechanical displacement of the diaphragm. Basic performances of the liquid delay line and measurement results for vibration displacement are presented.
Detection of Ultrasonic Longitudinal and Shear Waves Using Optical Heterodyne Interferometer
Authors: Hisashi Yamawaki Hisashi Yamawaki , Tetsuya Saito Tetsuya Saito
Published: October 2002

An optical heterodyne interferometer was developed to enable noncontact detection of ultrasonic motions parallel and perpendicular to the specimen surface. Two optical setups, one for the parallel direction and another for the perpendicular direction, were included in the interferometer. The interferometer enabled simultaneous ultrasonic detection in both directions at the same point on the specimen surface without changing the optical layout of the interferometer. For verification of the technique, longitudinal and shear ultrasonic waves generated by piezoelectric transducers were detected by the interferometer.
Molecular Dynamics Approach to the Mode Analysis of Optical Waveguides
Authors: Haruhito Noro Haruhito Noro , Kouji Fukushi Kouji Fukushi , Tsuneyoshi Nakayama Tsuneyoshi Nakayama
Published: October 2002

A novel numerical method, based on a molecular dynamics algorithm for coupled harmonic oscillators, is applied to the mode analysis of arbitrary-shaped optical waveguides. We describe in detail the relationships between the vibrational equation of motion for lattice dynamics and the discretized form of the wave equation for light. This mapping is useful for the analysis of the characteristics of optical waveguides. The efficiency of the method is demonstrated by application of the method to the mode analysis of a semiconductor rib-waveguide.
Transmission Line Model Equivalent Circuit for Piezoelectric Transducers Including the Effect of Electrical Terminal Impedance
Authors: Kim Noriyoshi Chubachi
Published: October 2002

A new transmission line model equivalent circuit for a thickness-mode piezoelectric vibrator is derived. The equivalent circuit includes an electrical impedance connected to the terminals of a piezoelectric vibrator. A bolt-clamped frequency-controllable piezoelectric transducer is analyzed by using the equivalent circuit. The changes in particle velocity distribution by varying the electrical impedance in the frequency-controllable ultrasonic transducer are measured by a noncontact method based on laser Doppler velocimetry. The changes in particle velocity distribution agree well with results calculated using the new equivalent circuit.
Ultrasonic Micromanipulator Using Visual Feedback
Authors: Masao Takeuchi Masao Takeuchi , Hidetaka Abe Hidetaka Abe , Kazuhiko Yamanouchi Kazuhiko Yamanouchi
Published: October 2002

We have proposed ultrasonic micromanipulation (UMM) techniques for micron-sized particles in liquid based on the radiation forces of very-high-frequency (VHF) ultrasound. In this paper, we report new UMM techniques using visual feedback techniques. To generate VHF ultrasound, a beam-width-compression leaky wave transducer with a frequency of 50 MHz is used. The 50-µm-diameter SiO2 glass sphere and the polystyrene sphere are used as test particles. As an example of two-dimensional manipulation, the transportation of particles along circle and character patterns are demonstrated. The selective trapping of a glass sphere is also shown.
Effects of Ultrasonic Irradiation on the Capacity of Lead Storage Batteries
Authors: Bai Xiao-liang , Ohdaira Etsuzo , Nobuyoshi Masuzawa Nobuyoshi Masuzawa , Masao Ide Masao Ide
Published: October 2002

Studies of ultrasonic application for increasing the capacity of lead storage batteries were attempted. However, conditions for ultrasonic wave irradiation were not clarified in these studies. This paper reports the relationship between the capacity increase and sound pressure as well as the ultrasonic irradiation cycle times. Experiments were conducted using a water tank in which lead storage batteries were placed. The sound pressures necessary for defining ultrasonic irradiation were measured precisely. It was found that the capacity of battery increased in proportion to ultrasonic irradiation time of up to 250 hours. The largest capacity increase was observed at sound pressures between 18–28 kPa. Above this sound pressure level, capacity increase saturated. At high pressures with cavitation, capacity increase was suppressed. This paper also describes the results of observation of the electrode surface with a field-emission scanning electron microscope (FE-SEM).
Half Adder Operation using Optoelectronic Integrated Functional Devices
Authors: Osawa Yasuhiro , Kondoh Hiroshi , Kiyoshi Yamaguchi Kiyoshi Yamaguchi , Shiro Satoh Shiro Satoh
Published: October 2002

We demonstrate half adder operation using only two optoelectronic integrated functional devices (OEFDs), each of which consists of a light-emitting diode and a heterojunction phototransistor. Half adder operation is realized by utilizing the mode transition dependence on the driving condition of the OEFDs. The sum of two optical inputs is incident on the two OEFDs simultaneously. SUM and CARRY optical outputs are emitted from the two devices. Experimental results of half adder operation using discrete OEFDs are given for static and dynamic cases. Static results using a half adder device with monolithically integrated resistors are also given.
Improvement of Magnetostatic Coupling in Reversal Magnetically Induced Superresolution
Authors: Kawano Toshifumi , Hidetaka Ito Hidetaka Ito , Hidemi Yoshida Hidemi Yoshida
Published: October 2002

Reversal magnetically induced super resolution (R-MSR) makes use of magnetostatic coupling, which is a very weak force, in contrast to exchange coupling. To avoid the disturbance by the unexpected external field during readout (H

r
), methods for improving the magneto static coupling were studied. The direction of magnetization in the grooves markedly affected the H

r
dependence. When the grooves were erased in the direction antiparallel to that of lands, the H

r
stability showed symmetrical dependence on the direction of applied field. Moreover, adding a flux sink layer on the memory layer was effective for improving H

r
stability on long recording marks. This layer induced leakage flux from the center of the long recording mark. Consequently, the readout field stability of 170 Oe could be obtained with a 1.6 µm mark length.
Computational Paradigms in Nanoelectronics: Quantum Coupled Single Electron Logic and Neuromorphic Networks
Authors: Supriyo Bandyopadhyay Supriyo Bandyopadhyay , Vwani Roychowdhury Vwani Roychowdhury
Published: October 2002

We describe a new class of nanoelectronic circuits where circuit functions are derived from cooperative, quantum mechanical interactions between single electrons confined in arrays of quantum dots. Two specific architectures are examined: (i) quantum coupled logic in which Boolean logic functions are implemented by quantum mechanical spin-spin interactions between single electrons in arrays of quantum dots, and (ii) quantum neuromorphic networks that exploit the complex spatial and temporal evolution of discrete charge in an ensemble of non-linearly interacting quantum dots to elicit collective computational behavior. The first class of circuits includes combinational and sequential digital systems. Both logically irreversible elements such as half-adders, S-R flip-flops, shift registers, ring counters, etc., and reversible Feynman gates for quantum computation have been designed in this paradigm. These circuits can be endowed with the required “unidirectional” (non-reciprocal) character that previous (flawed) designs of similar circuits lacked. The second class of circuits comprises discrete Hopfield networks which utilize single electron tunneling events in arrays of metallic islands to perform neuromorphic computation. They can solve NP-complete optimization problems (such as the traveling salesman problem), produce associative memory effects and also exhibit rudimentary image-processing capability.
Critical Current Densities and Irreversibility Fields of High Tc Superconductors, GaSr2Ca2Cu3O9 and BSr2Can-1CunO2n+3 (n= 3, 4)
Authors: Yu Shan , Okuda Yuichi , Kawashima Tetsuya , Takayama-Muromachi Eiji
Published: October 2002

From the hystereses in DC magnetization loops, we measured critical current densities J
c and irreversibility fields B
irr of high T
c superconductors, GaSr2Ca2Cu3O9 (Ga-1223) and BSr2Ca

n
-1Cu

n

O2
n
+3 ( B-12(n-1)n, n=3, 4) prepared at a high pressure of 6 GPa. These three phases with blocking layers consisting of single metal planes were expected to have high J
c and high B
irr. However, the present experiment revealed that their values for both J
c and B
irr were much smaller than those of the (Cu, C)-based oxides. This result suggests that the electronic structures of the present three phases are more anisotropic than those in the (Cu, C) phases in spite of their thinner blocking layers and that the thickness of the blocking layer, i.e., the spacing between the CuO2 multilayers, is not always a key parameter determining J
c and B
irr.
Prediction of Electromagnetic Properties of MnZn Ferrite-Silicone Rubber Composites in Wide Frequency Range
Authors: Byoung Taek Lee Byoung Taek Lee , Ho Chul Kim Ho Chul Kim
Published: October 2002

A method for calculating effective complex permittivity and permeability was proposed, and the reflection loss in a resonant absorber of two-phase ferrite composites was calculated using the effective medium theory incorporating the invariant the Debye-Hertz potential in the scattering of the Bruggeman effective medium structure. The validity of this approach was investigated for MnZn ferrite-silicone rubber composites with ferrite volume fractions varying from 0.1 to 0.4 in the frequency range between 45 MHz and 10 GHz. The agreement between the results calculated using the effective medium theory and the experimental results is excellent, which indicates that the frequency dependence of the electromagnetic properties and the reflection loss of ferrite composites can be predicted.
Optimization of Modulation Index for the Detection of Phase-Modulated Accumulated Photon Echo
Authors: Koreeda Akitoshi , Matsuda Kouhei , Makoto Mikami Makoto Mikami , Seishiro Saikan Seishiro Saikan
Published: October 2002

The optimum value of the modulation index which maximizes the signal intensity of the phase-modulated accumulated photon echo has been confirmed experimentally.
Environmental Effect on Ultrasmall Josephson Junctions
Authors: Shimazu Yoshihiro , Seiichiro Ikehata Seiichiro Ikehata , Shun-ichi Kobayashi Shun-ichi Kobayashi
Published: October 2002

In order to study the effect of environment on ultrasmall Josephson junctions, we measured the temperature dependence of the zero-bias resistance of single ultrasmall Josephson junctions with different lead resistances. The normal-state resistance of the junctions was chosen to be around the resistance quantum R
Q = h/4e
2 = 6.45 kΩ. We found that the temperature dependence was strongly dependent on the lead resistance. This result indicates that there exists a clear environmental effect on ultrasmall Josephson junctions. The observed environmental effect can be explained in terms of the difference of bias conditions or the noise effect on superconductivity, both of which can be effectively controlled by the lead resistance. The marked noise effect was also manifested by the magnetic field dependence of the V–I characteristics of linear junction arrays with tunnel resistances much lower than R
Q.
Zero-Loss Reflection High-Energy Electron Diffraction Patterns and Rocking Curves of the Si(111)7×7 Surface Obtained by Energy Filtering
Authors: Yoshimi Horio Yoshimi Horio
Published: October 2002

The improvement of a new type of reflection high-energy electron diffraction (RHEED) apparatus equipped with a retarding field analyzer is reported. Three kinds of meshes are examined for the retarding grids of the analyzer and their energy resolutions are checked. Electron beam trajectories passing through the analyzer are also simulated and the calculated spot sizes and shapes are compared with experimental ones. Very fine 250 mesh, used for the retarding grid, gives very good energy resolution of ΔE=4 eV with an incident beam energy of E=10 keV, and therefore ΔE/E = 4×10-4. Energy-filtered RHEED patterns and energy-filtered rocking curves are taken for the Si(111)7×7 surface and are compared with conventional ones. The advantages and characteristics of energy filtering are described in detail. Improved energy loss spectra for the 0 0 and 1 1 reflected beams are also presented. These clearly show surface plasmon loss peaks.
Appearance of Resistance Minimum in Nanocrystalline Films Prepared by Gas Deposition Method
Authors: Iwamoto Yoji , Kashuu Seiichirou , Sasaki Yuji , Kita Eiji , Tasaki Akira
Published: October 2002

Iron nanocrystalline films were prepared by a gas deposition method. The nanocrystal has a diameter of about 300 Å and its surface was covered with a 40-Å-thick oxide layer. The electric resistance versus temperature curve showed a minimum in the low-temperature region. The resistance minimum was analyzed from the viewpoint of electron hopping through the oxide layer on the nanocrystal surface.
Highly Selective SiO2/Si Etching and Related Kinetics in Time-Modulated Helicon Wave Plasma
Authors: Chinzei Yasuhiko , Shindo Haruo , Yasuhiro Horiike Yasuhiro Horiike
Published: October 2002

Highly selective SiO2/Si etching has been achieved by using time-modulated helicon wave plasma (HWP) employing C4F8/H2 mixture. Time modulation of less than 5 µ s. effectively controlled the electron energy, suppressing redissociation of HF. The selectivity window for H2 concentration was widened by synchronizing the phase of 100 kHz self-bias to the phase of 100 kHz time-modulated HWP. This is performed by extension of the polymer point to higher H2 concentration due to bombardment of more ions. Measurements of AMS of radicals and XPS of polymer formed on the Si surface suggest that CF1 radicals contribute to the polymer formation and produce carbon-rich film in the presence of hydrogen in the case of the pulse discharge in which electron energy is controlled and dissociation is suppressed. Measurement of CF1/F ratio also supported this conclusion.
Thermal Equilibrium Defects in Anthracene Probed by Positron Annihilation
Authors: Uedono Akira , Tachibana Masaru , Shimizu Mikio , Satoh Masaaki , Kojima Kenichi , Ishibashi Shoji , Kawano Takao , Shoichiro Tanigawa Shoichiro Tanigawa
Published: October 2002

Defects in anthracene were investigated by the positron annihilation technique. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured in the temperature range between 305 K and 516 K. The lifetime of positrons annihilated from the delocalized state was determined to be 0.306 ns around room temperature. Below the melting point, the observed temperature dependence of the line shape parameter S was explained assuming the formation energy of thermal equilibrium defects was 1 eV. Above the melting point, the pick-off annihilation of ortho-positronium in open spaces was observed, where the size of these spaces was estimated to be 0.2 nm3. The annihilation of positrons from the self-trapped state was also discussed.
Evaluation of CF2 Radical as a Precursor for Fluorocarbon Film Formation in Highly Selective SiO2 Etching Process Using Radical Injection Technique
Authors: Takahashi Kunimasa , Hori Masaru , Muneto Inayoshi Muneto Inayoshi , Toshio Goto Toshio Goto
Published: October 2002

A radical injection technique (RIT) was developed to evaluate CF2 radical as a precursor for fluorocarbon film formation in a highly selective SiO2 etching process. Using RIT, the CF2 radical was successfully injected into electron cyclotron resonance (ECR) downstream plasmas employing Ar and H2/Ar mixtures. The fluorocarbon films formed on the Si surfaces exposed to ECR downstream plasmas were investigated using X-ray photoelectron spectroscopy. The deposition rate of fluorocarbon films was measured by varying microwave power in the Ar and H2/Ar ECR plasmas while keeping CF2 radical density constant using RIT. From the experimental results, it was found that the CF2 radical was the important precursor for fluorocarbon film formation only with the assistance of the surface activation due to the plasma exposure and that H atoms and CF2 radicals in the plasma played an important role in the formation of carbon-rich fluorocarbon film resulting in highly selective SiO2 etching. Furthermore, the highly selective SiO2 etching was demonstrated using the H2/Ar ECR downstream plasma with CF2 radical injection.
Negative Conductance in Coulomb Blockade
Authors: Makoshi Takashi Mii
Published: October 2002

Based on the Anderson model with nonequilibrium distribution, we discuss the current between two electrodes through an atom with a finite bias voltage. The Anderson model is used to study the Coulomb blockade phenomenon from the small system size limit. We employ the Mahanthappa-Baksi-Keldysh Green function formalism to deal with the nonequilibrium system. The second-order perturbation study with respect to the Coulomb interaction between electrons in the atomic orbital is performed by starting with the restricted Hartree-Fock solution. We show results of various cases of the relative position of energy level on the atom with respect to the Fermi energies in two electrodes. Several behaviors of the conductance, such as the Kondo-assisted tunneling and blocking of the current by the Coulomb repulsion, are found. It is also shown that the conductance can be negative under special conditions. We discuss the physical nature of these effects in terms of the local density of states on the atom.
Observation of Gold Thin Film on Cesium Graphite Intercalation Compound by Scanning Tunneling Microscopy
Authors: Kinno Teruyuki , Miyoko O. Watanabe Miyoko O. Watanabe , Koichi Mizushima Koichi Mizushima
Published: October 2002

Thin film on stage-1 cesium graphite intercalation compound (Cs-GIC) which is known to be of very low work function has been studied using scanning tunneling microscopy (STM). After a small amount of Au was evaporated onto a Cs-GIC cleaved under ultrahigh-vacuum conditions, its surface was observed. At first, many islands with a diameter of several nanometers were found. These islands, however, gradually disappeared from the scanned region during observation. Our results suggest that the interaction of Au islands with Cs-GIC is weak, in spite of the large difference in work function between them.
Investigation of Ferroelastic Domain Boundary Structures of MP 5O 14 (M: La-Tb) and LaNbO 4 by Means of Scanning Tunneling Microscope, Atomic Force Microscope, X-Ray and Neutron Diffraction Analyses
Authors: Tadashi Kobayashi Tadashi Kobayashi , Iwao Takei Iwao Takei , Mitsuo Machida Mitsuo Machida , Yasutaka Suemune Yasutaka Suemune
Published: October 2002

The ferroelasticity of MP5O14 (M: La-Tb) which has the commensurate W domain boundary and LaNbO4 which is believed to have the incommensurate W' domain boundary has been studied by scanning tunneling microscope (STM), tapping-mode atomic force microscope (AFM) with a heat-supplying apparatus, time of flight (TOF) neutron diffraction and X-ray diffraction analyses. The tapping-mode AFM image of a GdP5O14 ferroelastic boundary wall shows a zigzag surface structure in which hollows, with a width of 500–600 nm and a depth of 1 or 2 nm, are aligned along the domain boundary. Our neutron and X-ray structural analyses of LaNbO4 confirm that there is no incommensurate W' domain wall within experimental error.
Effect of Penetration Depth on Electrical Properties in Pd/Ge/Ti/Au Ohmic Contact to High-Low-Doped n-GaAs
Authors: Kwak Joon Seop , Lee Jong-Lam , Baik Hong Koo , Shin Dong Won , Park Chan Gyung , Kim Haecheon
Published: October 2002

Penetration depth of Pd/Ge/Ti/Au ohmic contact to high-low-doped n-GaAs has been investigated using cross-sectional transmission electron microscopy, and the results are used to interpret the electrical properties. The ohmic metals do not penetrate into the GaAs substrate at 300° C, but penetrate deeper than 1000 Å into GaAs at 380° C. This is due to fast indiffusion of Au toward the GaAs substrate through the grain boundary of the PdGe compound, followed by formation of AuGa through reaction with GaAs. The deep penetration into GaAs at 380° C results in the lowest contact resistance of 0.43 Ω mm due to direct contact of ohmic metals with the buried high-doped GaAs layer.
Influences of Interface Roughness Scattering on Asymmetric and/or Steplike Current–Voltage Characteristics of Resonant Tunneling Diodes
Authors: Wang Shui-Jinn , Lin Jia-Chuan , Liou Wan-Rone , Yeh Mei-Ling , Ying-Che Luo Ying-Che Luo , Ching-Yuan Cheng Ching-Yuan Cheng
Published: October 2002

The influences of interface roughness (IR) scattering on transmission coefficient and current-voltage ( I–V ) characteristics of double-barrier resonant tunneling diodes are investigated. Simulation results reveal that asymmetric interface roughness scattering on different interfaces of the heterostructure may result in asymmetric I–V characteristics. In addition, it is suggested that the splitting of subband energy levels inside the quantum well caused by IR with large terraces (≥15 nm) may be one of the causes leading to a steplike I–V curve in the negative differential resistance region.