bluuebunny/crossref_metadata_2025 huggingface dataset:
Anomalous Photoconductivity in SrTiO3
Authors: Katsu Hayato , Tanaka Hidekazu , Kawai Tomoji
Published: October 2002

We have measured the photoconductivity of insulative SrTiO3 single crystal
whose band-gap is 3.2 eV. We have found that the dependence of resistivity on
temperature shows metallic conduction under white light irradiation and the
resistivity drops rapidly below 105 K. This temperature at which a giant
photoconductivity phenomenon occurs coincides with that of the cubic-to-tetragonal
structural phase transition, suggesting that the anomalous photoconductivity is related
to the structural phase transition.
Growth and Defect Characterisation in Single Crystals of Ferroelectric Ammonium Sulphate
Authors: Sen Gupta Suparna , Karan Susmita , Sen Gupta Siba Prasad
Published: October 2002

Some observations of growth hillocks, growth spirals and layers
on the chemically etched as-grown (100) faces of ammonium sulphate,
(NH4)2SO4 crystals obtained at 26°C from aqueous solutions of different pH are reported and discussed for the first time with
greater details. Optical and scanning electron microscopy show a
good correspondence between etch pits and dislocation behaviour.
Disappearance of Ohmic Loss Corresponding to Disappearance of Resistance in Very Thin Al Film
Authors: Hino Taro
Published: October 2002

A very thin Al film of 700 Å or 430 Å thickness was
evaporated on an arachidic acid Langumuir-Blodgett film which was
deposited on a SiO2 film present on a silicon wafer substrate.
No temperature rise of the very thin Al film was observed
in the current range for which the resistance of the
very thin Al film disappeared.
Accumulation Effect of Bombarding N2
+ Ions in Al for Crystal Growth of AlN Film
Authors: Mitsuhashi Riichirou , Beag Young Whoan , Shimizu Ryuichi
Published: October 2002

Dynamic observations of crystallographic structure by reflection high energy
electron diffraction (RHEED) and measurement of sputtering yield with a quartz
oscillator were performed simultaneously for an Al surface under 12 keV N2
+
ion bombardment, in order to elucidate the optimum conditions for crystal growth of
AlN. A simple theoretical model of sputtering was used to evaluate the accumulation
of N-atoms, and a surface concentration of implanted N-atoms of ∼44 at.%
was estimated, close to the stoichiometric concentration of AlN. Thus, AlN crystal
growth under 12 keV N2
+ ion bombardment was achieved with considerable
success.
Modeling of Electron Temperature in H-Ion Source
Authors: Morishita Takatoshi , Ogasawara Masatada , Hatayama Akiyoshi
Published: October 2002

The equation of electron temperature is included in a two point numerical code for a high power hydrogen negative ion source. The calculated results of the electron temperature are in good agreement with Japan Atomic Energy Research Institute (JAERI)'s experimental results. The scaling law of electron temperature is estimated as a function of input power and gas pressure. Energy input by arc discharge, energy loss by ionization, dissociation and loss on the wall are considered in the electron energy equation. The leak width on the wall at the cusp magnet is also calculated numerically. Energy loss on the wall is dominant, and is larger than the ionization loss. In a similarly enlarged JAERI's Kamaboko source, electron density increases and electron temperature decreases under a constant energy input per unit volume. In this situation, H-extraction current increases despite the decrease in H-density because of the enlargement of the H-extraction area.
Light Bounces in Two-Beam Scanning Laser Interferometers
Authors: Hiroyuki Fujimoto Hiroyuki Fujimoto , Giovanni Mana Giovanni Mana , Kan Nakayama Kan Nakayama
Published: October 2002

The article deals with the effects of light bounces in high-accuracy two-beam interferometers. Particular attention is given to systematic errors. Detailed calculations throw light on so far unexplained periodic variations we observed in the traveling-fringe period and explain them as the fingerprint of a three-beam interference pattern.
Silicon Micromachined Ultrasonic Transducers
Authors: Khuri-Yakub Butrus T. , Cheng Ching-Hsiang , Degertekin Fahrettin-Levent , Ergun Sanli , Hansen Sean , Jin Xue-Cheng , Oralkan Omer
Published: October 2002

This paper reviews capacitor micromachined ultrasonic
transducers (cMUTs). Transducers for air-borne and immersion
applications are made from parallel-plate capacitors whose
dimensions are controlled through traditional integrated circuit
manufacturing methods. Transducers for airborne ultrasound
applications have been operated in the frequency range of
0.1–11 MHz, while immersion transducers have been operated in the
frequency range of 1–20 MHz. The Mason model is used to represent
the cMUT and highlight the important parameters in the design of
both airborne and immersion transducers. Theory is used to compare
the dynamic range and the bandwidth of the cMUTs to piezoelectric
transducers. It is seen that cMUTs perform at least as well if not
better than piezoelectric transducers. Examples of single-element
transducers, linear-array transducers, and two-dimensional arrays of
transducers will be presented.
Ultrasonic Behavior of Ti0.49–Ni0.51 Shape Memory Alloy between 0°C and 90°C
Authors: Kashiwagura Nobuo , Ohsawa Yoshiyuki , Iwata Shinichi , Jin Ji-Ye , Kamioka Hiroaki
Published: October 2002

Shear and compressional wave velocities and attenuation in
Ti0.49–Ni0.51 shape memory alloy were accurately measured
for rhombohedral phase transformation by the pulse transmission
method using a dual acoustic path over the temperature range between
0°C and 90°C. The temperature dependence of the
compressional and shear wave velocities showed a minimum over the
temperature range between 0°C and 40°C. Various
attenuation peaks of compressional and shear waves appeared. These
peaks correspond to the temperatures near the characteristic
temperatures of the transformation. From measured ultrasonic data,
the elastic and inelastic properties of Ti0.49–Ni0.51
shape memory alloy are discussed.
Photoplastic Effect of NaCl Single Crystal
Authors: Tateno Hiroto , Okawa Takafumi , Iwashita Yoichiro
Published: October 2002

To clarify photoplastic effects, the Young's modulus and
internal friction of NaCl single crystals were measured by the
automated Marx's composite oscillator method. The experimental
results suggest that pinning of the metallic impurity and cation
vacancy couples were released by light illumination, and the
F-center and M-center produced by γ-ray irradiation emit
internal free electrons.
Difference in Threshold between Sono- and Sonochemical Luminescence
Authors: Shin-ichi Hatanaka Shin-ichi Hatanaka , Kyuichi Yasui Kyuichi Yasui , Toru Tuziuti Toru Tuziuti , Hideto Mitome Hideto Mitome
Published: October 2002

The difference in threshold between sonoluminescence (SL) and sonochemical
luminescence (SCL) has been investigated. The intensity of both SL from distilled water and
SCL from a luminol solution in a rectangular glass cell was measured while changing the
driving frequency and voltage applied to the transducer. The second hamonic component of the
sound-pressure waveform was also measured simultaneously. The results show that the thresholds
in sound pressure become higher for cavitation, SCL and SL in this order. As the dissolved gas in a
liquid decreases, the SCL intensity decreases but the SL intensity increases. For a constant quantity
of dissolved gas, as the liquid temperature becomes higher, the SCL intensity increases but the SL
intensity decreases. In the case of air-saturated liquids, the difference in threshold between SCL
and SL becomes larger as the liquid temperature increases. The dependence of the ratio of SCL to
SL on temperature is similar to that of vapor pressure.
Parameters of Coupling-of-Modes Equations for a Natural Single-Phase-Unidirectional Transducer on a La3Ga5.5Nb0.5O14 Substrate
Authors: Inagawa Kiyoshi , Hasegawa Koji , Koshiba Masanori
Published: October 2002

Parameters included in coupling-of-modes equations such as
coupling coefficients, transduction coefficients and electrostatic
capacitances are theoretically determined for a natural single-phase
unidirectional transducer (NSPUDT) on a
La3Ga5.5Nb0.5O14 substrate with Euler angles of
(110°, 145°, 145°) and an
electromechanical coupling coefficient larger than quartz. In the
hybrid finite-element method (HFEM), used for determining these
parameters, all the effects of anisotropy of the substrate,
piezoelectric perturbation, mechanical perturbation and energy
storage are taken into account. The electrode thickness and width
dependence of the parameters and the excitation characteristics of
NSPUDT are investigated in detail. The parameters obtained by the
present method are compared with those obtained by the perturbation
method. Furthermore, numerical results for the frequency
characteristics of NSPUDT are compared to the experimental data, and
the validity and usefulness of the present method are demonstrated.
Theoretical Analysis of Surface Acoustic Wave Propagation Characteristics under Strained Media and Applications for High Temperature Stable High Coupling Surface Acoustic Wave Substrates
Authors: Yamanouchi Kazuhiko , Kotani Kenji , Odagawa Hiroyuki , Cho Yasuo
Published: October 2002

Among the important properties required for surface acoustic waves (SAW)
substrates are a large electromechanical coupling coefficient (k
2), small
temperature coefficient of frequency (TCF) and low propagation loss. The LiNbO3
and LiTaO3 have good properties as the SAW substrates with a large size.
Unfortunately, these possess the defect of having large values of TCF. In this paper,
SAW-bonded composite substrates with a large k
2, small TCF, low propagation loss
and no dispersion using conventional bonders are investigated theoretically and
experimentally. The propagation characteristics of SAWs under strained piezoelectric
crystals using the higher-order elasticity theory have been analyzed. The theoretical
results show zero TCF on LiNbO3/SiO2 substrates. The experimental results
for LiNbO3/glass substrates revealed a TCF of [-19 ppm/°C]. The
propagation properties were almost the same as those of the single crystal.
Effect of Stepped Bi-Mesa Structures on Spurious Vibrations of AT-Cut Quartz Plates
Authors: Goka Shigeyoshi , Ishizaki Akio , Sekimoto Hitoshi , Watanabe Yasuaki
Published: October 2002

In this paper, the effect of stepped bi-mesa structures on the
coupling of vibrations in AT-cut quartz plates is analyzed
theoretically. Since strong coupling of thickness-flexure modes are
of interest, straight-crested waves propagating along the X axis
are treated. Calculated results for the stepped bi-mesa structure
show that the coupling strength as estimated from its mode chart
decreases to about one-third that of a bi-mesa resonator. The
characteristics of bi-mesa structures appear to be amenable to
further improvement by the use of a stepped bi-mesa structure.
Multimode Quartz Crystal Microbalance
Authors: Goka Shigeyoshi , Okabe Kiwamu , Watanabe Yasuaki , Sekimoto Hitoshi
Published: October 2002

In this paper, a quartz crystal microbalance (QCM) gas sensor using multiple
resonant modes is studied.
In this QCM gas sensor, the absorbent is not
fully deposited onto the plate surface as in the case of conventional
QCM gas sensors.
The absorbent is coated on the plate surface,
where the external-stress-sensitivity
difference between the two modes used is greatest.
To confirm the validity of multimode QCMs,
we fabricated multimode QCM devices;
a polyimide thin film
is used as the adsorbent of carbon dioxide, and an 11 MHz AT-cut quartz
resonator is used.
Efficient Optical Mode Conversion Induced by Magnetostatic Surface Waves in Three-Dimensional Optical Waveguide
Authors: Rakesh Bhandari Rakesh Bhandari , Yasumitsu Miyazaki Yasumitsu Miyazaki
Published: October 2002

A multilayered garnet device is proposed and analysed to obtain efficient optical mode conversion induced by magnetostatic surface waves (MSSW) in a three-dimensional optical waveguide, suitable for integrated optics. The device parameters, including the layer thicknesses, waveguide width, and the saturation magnetization of the garnet layers, are optimized to shorten the coupling length. A numerical example demonstrates the feasibility of 100% optical mode conversion with practical device dimensions.
Determination of the Polarities of ZnO Thin Films on Polar and Nonpolar Substrates Using Scanning Nonlinear Dielectric Microscopy
Authors: Satoshi Kazuta Satoshi Kazuta , Yasuo Cho Yasuo Cho , Hiroyuki Odagawa Hiroyuki Odagawa , Michio Kadota Michio Kadota
Published: October 2002

Using scanning nonlinear dielectric microscopy (SNDM) which we developed, we determined the polarities of ZnO thin films on various substrates including polar materials.
SNDM is a useful tool for investigating the anisotropy of polar materials by measuring the nonlinear dielectric constant, whose sign changes in accordance with the polarity of the specimen.
In conventional methods based on detecting the piezoelectric and pyroelectric responses, it is very difficult to determine the polarities of thin films, particularly in the case of laying these films on the polar substrates, because the detected signals from thin films are very small and those from the substrates are large.
Our SNDM method, however, enables us to determine the polarities of thin films on polar substrates easily.
Using SNDM, the polarities of ZnO thin films on several kinds of polar and nonpolar substrates were determined.
We also determined experimentally that ZnO thin films grew with a sign opposite to the substrate polarity and it was suggested that pyroelectric effects mainly governed the polarity of ZnO films.
Periodic Property of Domain in Nematic Liquid Crystal Induced by Elastic Wave
Authors: Masaru Inoue Masaru Inoue , Hiroshi Moritake Hiroshi Moritake , Kohji Toda Kohji Toda
Published: October 2002

Periodic domain patterns have been observed in a nematic liquid crystal
cell induced by an elastic wave which propagates on a glass plate over a wide
frequency range.
The frequency dependence of the periodic length of the domain pattern is
measured and a numerical analysis of elastic wave propagation is
carried out in a sandwiched glass-nematic-glass medium.
One of the three modes existing in the liquid crystal cell region is
related to the longitudinal wave velocity in the liquid crystal.
The longitudinal wave velocity in the nematic liquid crystal
N-(p-methoxybenzylidene)-p'butylaniline)] (MBBA) is evaluated in the
relation to the periodicity of the domain pattern.
A Study on the Conditions for Generation of Monopole Ultrasonic Pulse by Piezoelectric Polymer Film Transducers
Authors: Hiroyuki Monma Hiroyuki Monma , Yasuo Yoshida Yasuo Yoshida , Kazuhiko Imano Kazuhiko Imano , Hiroshi Inoue Hiroshi Inoue , Kenji Murata Kenji Murata
Published: October 2002

Short monopole ultrasonic pulses can be radiated from piezoelectric polymer film transducers driven by a step-function voltage with a fast rising time and low output impedance. In this study, we investigated the conditions for transmitting a monopole ultrasonic pulse by simulation and experiment. We clarify that the length of the pulse width is limited by transmission time (Th
) in the direction of the thickness of the film transducer. By the simulations and experiments with the received pulse by changing the acoustic impedance of the backing material, it was also found that the backing material should be matched when the rising time of the driving step-function voltage is shorter than Th
. It is also shown that the source impedance of the driving circuit is an important factor in generating short ultrasonic pulses.
Highly Accurate Composition Analysis of (Pb,Zr)TiO3 Using a Scanning Electron Microscope/Energy Dispersive X-Ray Spectrometer
Authors: Suga Mitsuo , Torii Kazuyoshi , Kumihashi Takashi , Kakibayashi Hiroshi
Published: October 2002

A highly accurate composition analysis method for (Pb,Zr)TiO3
(PZT) thin films was developed that uses a scanning electron
microscope/energy dispersive X-ray spectrometer (SEM/EDX). This
method, highly accurate (HA)-SEM/EDX, consists of two measurements
with different electron beam acceleration voltages to control the
signal generation depth. The measurement time is sufficiently
elongated to reduce the statistical noise. Measurement accuracy of the
PZT composition is ±1%, which is sufficient to predict the electrical
characteristics of PZT capacitors. We applied
HA-SEM/EDX to the failure analysis of PZT
capacitors, and found that composition variation
was the cause of failure in both failed samples
we examined. The composition variations of PZT
within a Si wafer were also measured. The
composition variation of a PZT film fabricated
by the sol-gel method was over ±2%, which was
much larger than that of PZT deposited by ozone
jet evaporation method (±1%).
Inverse Scattering Image Reconstruction from Reflection and Transmission Data Obtained Using the Mirror Image Theory
Authors: Jung-Soon Kim Jung-Soon Kim , Akira Yamada Akira Yamada
Published: October 2002

The inverse scattering technique is expected to be useful to obtain quantitative acoustic parameter images of tissues in the human body. However, the difficulty of making observations around the 360° circumference of an object hinders the realization of the technique. In this paper, to mitigate the restrictions on observations, a reflection plate is placed behind an object and the problem of reconstructing an image from the reflection and transmission data at the half-circumference points around the object is considered. To this end, a technique is proposed based on the treatment of the conventional transmission inverse scattering problem using the mirror image theory. The validity of the method is tested using simulated data from an elliptical object. As a result, the precision of the reconstructed sound velocity image is verified to be almost satisfactory for the purposes of medical diagnostic applications.
A New Modeling for the Changes in the Distribution of Scatterers in Cirrhotic Liver
Authors: Takashi Hara Takashi Hara , Hiroyuki Hachiya Hiroyuki Hachiya
Published: October 2002

The human liver is composed of small hexagonal structures called liver lobules. Cirrhosis destroys these liver lobules and replaces them with permanent connective tissue referred to as regenerative nodules.
In this paper, we propose a new modeling technique for changes in the scatterer distribution in liver tissue considering the structure of liver lobules to obtain images of the cirrhotic liver over continuous stages. Using these images, we analyze the relationship between changes in characteristics of biological tissue and changes in B-mode images during progressive liver cirrhosis.
Extraction of Quantitative Three-Dimensional Information from Ultrasonic Volumetric Images of Cirrhotic Liver
Authors: Tadashi Yamaguchi Tadashi Yamaguchi , Hiroyuki Hachiya Hiroyuki Hachiya , Kazuki Kato Kazuki Kato , Hiroyuki Fukuda Hiroyuki Fukuda , Masaaki Ebara Masaaki Ebara
Published: October 2002

The cirrhotic liver has many fibrotic tissue structures known as nodule structures.
Understanding this characteristic in diseased tissue is important for quantitative diagnosis.
In this paper, we present a technique to extract quantitative three-dimensional information from a cirrhotic liver.
Consecutive two-dimensional images acquired by fan like scanning were processed using constant false alarm rate (CFAR).
The 2D processed images are accumulated to obtain 3D information.
The nodular structure is clear in the constructed images.
In Situ Observation of the Interfacial Phase Formation at Si Melt/Silica Glass Interface
Authors: Huang Xinming , Wang Tiefeng , Yamahara Keiji , Taishi Toshinori , Hoshikawa Keigo
Published: October 2002

In situ observation has been carried out to investigate the
interfacial phase of “brownish rings” forming at the Si
melt/silica glass interface during Czochralski (CZ) silicon crystal
growth. It is found that some small brownish dots appeared at the
interface immediately after Si melting, and gradually grew
laterally. The growth rate of the interfacial phase increases with
increasing temperature, and it only nominally depends on the silica
dissolution rate when the dissolution rate is lower than a critical
value. The formation mechanism of the brownish rings has been
investigated and two formation mechanisms are proposed. (1)
Cristobalite forms in the central region of the interfacial
phase. (2) The periphery of the interfacial phase is thicker than
the central region, and only part of the periphery remains after
passing through the triple junction where the dissolution rate is
very high.
Magneto-Photoluminescence Study of InGaAs/GaAs Quantum Wells and Quantum Dots Grown on (111)B GaAs Substrate
Authors: Tyan Shing-Long , Shields Philip A. , Nicholas Robin J. , Tsai Fu-Yi , Lee Chien-Ping
Published: October 2002

InGaAs/GaAs quantum well (QW) and quantum dot (QD) structures grown on GaAs
(111)B substrates under different growing temperatures are investigated by
magneto-photoluminescence (PL) up to 15 T in both Faraday and Voigt configurations.
The spatial extents of the carrier wave functions (ECWFs) are deduced from the
diamagnetic shift of the PL peak energy. The binding energies of the InGaAs/GaAs QWs
are evaluated to be about 5 meV. The QW ECWFs in the growth direction obtained by
the diamagnetic shift are consistent with those calculated by the k ·p theory.
The heights and radii of the InGaAs/GaAs QDs are also estimated from the ECWFs.
In addition, we found that the in-plane ECWFs decreased slightly as the growth
temperature was varied from 525 to 450°C. The ECWFs in the growth direction
decreased when the growth temperature was varied from 525 to 480°C and then
increased as the temperature was decreased to 450°C.
Fabrication of Polycrystalline Silicon Films from SiF4/H2/SiH4 Gas Mixture Using Very High Frequency Plasma Enhanced Chemical Vapor Deposition with In Situ Plasma Diagnostics and Their Structural Properties
Authors: Nakahata Kouichi , Ro Kazuyoshi , Suemasu Atsushi , Kamiya Toshio , Fortmann Charles Michael , Shimizu Isamu
Published: October 2002

Polycrystalline silicon (poly-Si) films were fabricated by very high frequency (VHF)
plasma enhanced (PE) chemical vapor deposition (CVD) from SiF4 and H2 gas mixture with
small amounts of SiH4. Reactions and growth of poly-Si in the SiF4/H2/SiH4 system were
discussed together with the results obtained from in situ plasma diagnostics, and compared
with those obtained by microwave PECVD (MW CVD). As a result, similar relationships
among growth temperature, SiF4/H2 gas flow ratio and film structure to those obtained with
MW CVD were obtained with VHF CVD. For example, growth temperature could be reduced
to 100°C while keeping a high crystal fraction (>80%) when small SiF4/H2 gas flow ratios
were used. In contrast, under large SiF4/H2 gas flow ratios, crystal fraction rapidly decreased
with decreasing temperature. The role of fluorine-related species in the growth of poly-Si was
examined in relation to film microstructure and the results obtained from plasma
diagnostics. Finally, guiding principles to achieve high rate and/or low-temperature growth of
poly-Si by VHF CVD using SiF4/H2 gas mixtures were discussed.
The Influence of the Addition of CaO on the Magnetic and Electrical Properties of Ni–Zn Ferrites
Authors: Ali Nazia Jabeen , Rahman Jalalur , Chowdhury M. Amanullah
Published: October 2002

The addition of CaO on magnetic and electrical properties of
Ni–Zn ferrite has been studied for the first time in this research
work. CaO is new in this field. The ionic radius of
Ca2+(0.94 Å) is large as compared to that of
Ni2+(0.68 Å) and Zn2+(0.69 Å). So, the
main interest of this study was to investigate the properties of
Ni–Zn ferrite with CaO additive. Various percentages of CaO were
added to the Ni–Zn ferrite of composition
Ni0.3Zn0.7Fe2O4. It was shown that CaO additive
act beneficially on the densification and on
improvement of electrical and magnetic properties of ferrite
samples.
Polarization-Independent Optical Properties of Liquid Crystal Polarization-Converting Devices
Authors: Michinori Honma Michinori Honma , Susumu Sato Susumu Sato
Published: October 2002

The transmitted light intensity of liquid crystal (LC) polarization-converting devices is measured in detail and found to be independent of the polarization state of the incident light and the rotation angle of the analyzer θA. The focusing properties of the light transmitted through two types of LC polarization-converting devices (±90° and ±180° twist modes) and the fiber coupling properties are measured and discussed. Unlike the ±90° twist mode, in the ±180° twist mode, the distribution profile of the focusing spot does not change even if the analyzer is rotated. Furthermore, the coupling efficiency in the ±180° twist mode is independent of θA and the polarization state of the incident light. An optical system for light beam separation that is independent of the polarization state of the incident light beam is proposed as an application of the LC polarization-converting device.
AlAs Oxidation System with H2O Vaporizer for Oxide-Confined Surface Emitting Lasers
Authors: Arai Masakazu , Nishiyama Nobuhiko , Shinada Satoshi , Koyama Fumio , Iga Kenichi
Published: October 2002

We have developed an oxidation apparatus with high
reproducibility for fabricating oxide-confined vertical cavity
surface emitting lasers (VCSELs). Precise control of AlAs oxidation
can be realized for a high-performance VCSEL array in mass
production. In this system, we introduce a vaporizer with a water
mass flow controller for stable and precise control of H2O
vapor. We have achieved good reproducibility and
controllability. The run-to-run deviation of the oxidized window is ±0.1 µm for nominal ∼10.4 µm oxidation.
Crystal Orientation Effects on Electronic Properties of Wurtzite GaN/AlGaN Quantum Wells with Spontaneous and Piezoelectric Polarization
Authors: Park Seoung-Hwan
Published: October 2002

Crystal orientation effects on electronic properties of a WZ GaN/AlGaN quantum well (QW) with spontaneous (SP) and piezoelectric (PZ) polarization are invetigated using the multiband effective-mass theory. The interband transition energy for the flat-band (FB) model without SP and PZ polarization shows a slow decrease with increasing crystal angle. On the other hand, the self-consistent (SC) model shows a significant redshift for cystal angles near θ=0 and a rapid increase of the interband transition energy due to the reduced SP and PZ ploarization effects. The SC model also shows that the matrix elements are significantly reduced near the (0001) orientation due to the large spatial separation between electron and hole wave functions. However, it is observed that the matrix elements rapidly increase with crystal orientation. In the case of the average hole effective mass, both SC and FB models show that their effective mass is significantly reduced near the (1010) crystal orientation. These results mean that the non-(0001) QWs, particularly the (1010) QWs, have a much smaller effective mass and larger matrix elements compared to those of the conventional (0001)-oriented QW.
The Microwave Dielectric Properties and the Microstructures of La2O3-Modified BiNbO4 Ceramics
Authors: Huang Cheng-Liang , Weng Min-Hang , Wu Cheng-Cher
Published: October 2002

The microwave dielectric properties and the microstructures of
La2O3-modified BiNbO4 ceramics were investigated.
(Bi1-x
La
x
)NbO4 ceramics combined with orthorhombic and triclinic
phases are identified at sintering temperatures of 920–980°C. The
density and grain size of (Bi1-x
La
x
)NbO4 ceramics both increase with
increasing sintering temperature while both decrease slightly with the increase of
La2O3 content. The dielectric constant ε
r, the quality
factor Q and the temperature coefficient of resonant frequency τf of
the ceramics are affected by the La2O3 content and correlated with its
microstructure. At a sintering temperature of 920°C and x value of 0.01,
(Bi1-x
La
x
)NbO4 ceramics exhibit the microwave dielectric properties of
ε
r∼43.36, Q×f∼10600 (at 7 GHz), and
τf∼-2 ppm/°C.
Determination of Electrostrictive and Third-Order Dielectric Constants of Piezoelectric Ceramic
Authors: Cho Yasuo
Published: October 2002

In this study, all six electrostrictive constants and all two third-order dielectric constants of lead zirconate titanate (PZT) ceramic are measured. To measure electrostrictive constants, new dynamic measuring methods to obtain capacitance variation with alternating stress and alternating electric field were used. These new methods enable us to obtain the electrostrictive constants and the third-order dielectric constants in the state of fixed polarization without an aging effect. These measured constants, defined in the d-form basic piezoelectric equation in which the electric field and stress are chosen to be independent field variables, are transformed into the constants defined in the g-form where electric displacement and stress are independent field variables for the reader's convenience.
Fabrication of Langmuir–Blodgett Films of β-carotene by Flow-orientation
Authors: Toshihiko Matsuura Toshihiko Matsuura , Akira Nishimura Akira Nishimura , Yuhei Shimoyama Yuhei Shimoyama
Published: October 2002

Using the Langmuir–Blodgett (LB) method together with the flow-orientation technique which controls the flow of a film material on the subphase, we successfully fabricated a well-ordered film of β-carotene. The surface pressure–area isotherm suggested that β-carotene in a Langmuir monolayer oriented perpendicular to the water surface. The flow-orientation method enhanced the molecular orientation in the monolayer. X-ray diffraction patterns indicated that the orientation of β-carotene in the LB films correlates with the number of layers. The films with five and nine layers yielded tilt angles of 55° and 40°, respectively. Fourier-transform infrared spectroscopy revealed that ionone rings of β-carotene in the LB film orient perpendicular to the gold substrate.
Hydrogen Gas Sensing Using a Pd-Coated Cantilever
Authors: Sumio Okuyama Sumio Okuyama , Yuichi Mitobe Yuichi Mitobe , Katsuro Okuyama Katsuro Okuyama , Koichi Matsushita Koichi Matsushita
Published: October 2002

A cantilever consisting of a thin glass plate coated with an evaporated Pd thin film can be utilized as a hydrogen gas sensor because the Pd film expands upon absorption of hydrogen, resulting in the bending of the free end of the cantilever. A comparison has been made between the response obtained experimentally from 100–1000-nm-thick Pd-coated glass plate cantilevers in the presence of 0.1–600 Torr hydrogen and the response calculated from the data of the Pd lattice expansion due to hydrogen absorption and the elasticity theory. It is shown that the Pd-coated cantilever can detect hydrogen at least from 0.1 to 10 Torr with good reproducibility. The use of a Pd–Ag alloy film instead of a pure Pd film was found to be effective both in enhancing the hydrogen sensitivity at low hydrogen pressures and in extending the hydrogen responsivity up to 600 Torr.
Development of New Apparatus for Field Emission Measurement
Authors: Lee Kuei-Yi , Ryu Jeong-Tak , Arimatsu Daiki , Kohara Hidekazu , Katayama Mitsuhiro , Wang Xiao Guang , Hirao Takashi , Oura Kenjiro
Published: October 2002

A field emission measurement profiler, which not only can measure the field emission of the entire film as well as its local points but also can present a two-dimensional map of the current density distribution, is developed. This apparatus is operated under an ultrahigh vacuum condition to measure the field emission distribution of amorphous carbon (a-C) films deposited by a RF magnetron sputtering system. The results show that the film surface consists of strong and weak emission sites. We also obtain the field emission maps of micrometer order from strong and weak emission sites; these can help us understand the mechanism of field emission for improving the procedure for growing films.
Improvement of Uneven Color of TiN Films Deposited by Arc Discharge Ion Plating
Authors: Akira Suzuki Akira Suzuki
Published: October 2002

The arc discharge ion plating technique has been widely applied for manufacturing decorative films such as TiN. This technique utilizes an electron beam gun for evaporation, an ionization electrode for arc discharge and a filament for the promotion of ionization. However, according to the position of the ionization electrode and filament, the films exhibit uneven coloring. New positions of the ionization electrode and the filament are devised. The color uniformity is improved using a filament which is placed under the electron beam passageway.
Absolute Calibration of Space- and Time-Resolving Flat-Field Vacuum Ultraviolet Spectrograph for Plasma Diagnostics
Authors: Okamoto Yuuji , Yoshikawa Masayuki , Yamaguchi Naohiro , Watabe Chikara , Tamano Teruo , Kawamori Eiichirou , Ito Takahiro , Watanabe Yoshihiko , Yatsu Kiyoshi
Published: October 2002

Measurement of spectra in the wavelength range from vacuum
ultraviolet (VUV) to soft X-ray is an important means to diagnose
impurities in magnetically confined plasmas used in fusion plasmas
such as a GAMMA10 plasma. Recently, a space- and time-resolving
flat-field grazing-incidence VUV spectrograph was constructed for
the simultaneous observation of spatial, temporal and spectral
distributions of plasma radiation in the wavelength range of
150–1050 Å. Absolute calibration experiments were performed at
beamline 11C in the Photon Factory at the High Energy Accelerator
Research Organization. The absolute efficiency of the VUV
spectrograph was measured for P polarization geometry in the
spectrograph.
Measurement of Evolved Hydrogen Volume during Anodization and Its Relationship to the Anodization Process
Authors: Akira Motohashi Akira Motohashi
Published: October 2002

It has been demonstrated that two hydrogen molecules evolve per dissolved silicon atom by anodization of silicon in HF solution, although a quantitative analysis has not been performed. The relationships of the volume of evolved hydrogen atoms n
H during anodization of silicon in HF solution to several anodization conditions, dissolved silicon atoms n
Si and charges n
hole were demonstrated. In the case of a degenerated silicon substrate, four hydrogen atoms were released as two gas molecules when a silicon atom was dissolved. In the case of a nondegenerated silicon substrate, with an increased HF concentration, the number of hydrogen atoms evolved per dissolved silicon atom was less than four, maintaining the relationship n
H+2.25n
hole=8.42n
Si. In this study, the relationship between the number of hydrogen atoms evolved and the silicon substrate resistivity was shown experimentally.
Spatial Resolution Improvement for Ultrasonic Imaging of an Object Consisting of Multiple Planes with Level Differences Using Contour Extraction
Authors: Michitoshi Noguchi Michitoshi Noguchi , Koichi Mizutani Koichi Mizutani , Keinosuke Nagai Keinosuke Nagai
Published: October 2002

The time of flight of sound is often used to measure the shape of an object. Ultrasonic imaging has an advantage of being non-destructive sensing. There is a close geometrical relationship between an ultrasonic beam and the spatial resolution of an acoustic image. Therefore, the realization of a high spatial resolution is difficult without adequate beam forming. In this paper, the spatial resolution improvement for the ultrasonic imaging of an object consisting of multiple planes with level differences in water is described. This imaging technique uses contour extraction and does not require focusing and beam forming. The ultrasonic transducer, used for the experiments, consists of a piezoelectric ceramic disk with a diameter of 4λ at the frequency of 3.5 MHz. The ultrasonic beam has a diameter of about 30λ at a distance of 200λ from the transducer. The resolution was improved by some countermeasures to compensate for the beam expansion. A contour extraction algorithm has been used in this experiment for image processing, in order to improve the spatial resolution around the edges of an object. A distinct advantage in using this algorithm is that the computational complexity is less than that required by other methods such as beam forming, neural networks and tomography algorithms. A distance error of 0.15 mm and a spatial error of ±0.5 mm were achieved using this system.
A Touch-Type Corrosion Sensor Including a Coil for High-Sensitive Detection of Initial Rust State
Authors: Yonemoto Naruto , Shida Katsunori
Published: October 2002

Some nondestructive diagnostic methods including the use of various types of corrosion sensors have recently been investigated. In this context, initial corrosion detection is a particular focus in our study. In order to detect the rust layer formed by some semiconductor materials, we have investigated several conventional touch-type corrosion sensors using the difference between the electrical characteristics of iron and rust. However, the sensitivity of these sensors was not sufficient to detect the impedance change of the rust layer due to the breakdown across the layer caused by the large transient supply current at the beginning of the measurement. This was because the impedance change at the breakdown happened to be much smaller than that without breakdown for thick rust layers. Here, we propose a new structure for a touch-type corrosion sensor, which includes a coil connected to a measurement electrode in series, to improve the characteristics of the sensor in the case of a thin rust layer. The transient supply current at the beginning of the measurement of the thickness of a rust layer is reduced by the effect of the connected coil. As a result, consistently accurate measurement by the sensor in the case of a thin rust layer is achieved.
Measurement of Porosity of Porous Silicon Using X-Ray Refraction Effect
Authors: Takehiro Maehama Takehiro Maehama , Atsushi Yonamine Atsushi Yonamine , Tomihiro Sonegawa Tomihiro Sonegawa , Nobuo Itoh Nobuo Itoh
Published: October 2002

A new method for the measurement of porosity in porous silicon , which enables us to determine the porosity of inner layers as well as that of each layer in multilayers using X-ray diffraction, is proposed. This method essentially applies the refraction of X-rays incident on the surface at a very small glancing angle for the separation of diffraction angles. To demonstrate the applicability of this method, the porosities of three samples of monolayers with different porosities and of a sample including multilayers were measured. The obtained values of porosities in monolayers are in good agreement with those obtained by the conventional gravimetric technique, and the value for each layer in the multilayers is consistent with the designed values for the multilayers. Thus, this method yields the porosities of various porous layers nondestructively; this has never been measured by conventional methods.
Touschek Lifetime of an Elliptical Electron Beam with Horizontal and Vertical Betatron Oscillations
Authors: Miyahara Yoshikazu
Published: October 2002

The Touschek lifetime of an elliptical electron beam is discussed considering the
horizontal and vertical betatron oscillations using the cross section for nonrelativistic
Möller scattering. Complex integration of the lifetime is numerically calculated and
formulated in an analytical expression for the convenience of practical application. The
present lifetime is reduced to the conventional ribbon beam formula in the extreme
case of a flat beam. The results agree with the lifetime experimentally determined in a
small storage ring, SOR-RING, in the whole range of small and large coupling of
horizontal and vertical oscillations.
Fabrication of Surface Acoustic Wave-Semiconductor Coupled Devices Using Epitaxial Lift-Off Technology
Authors: Hong Chulun , Koh Keishin , Kaneshiro Chinami , Aoki Yusuke , Hohkawa Kohji
Published: October 2002

In this paper, we report the results of a study on the fabrication process of
surface acoustic wave-semiconductor coupled devices, using epitaxial lift-off (ELO)
and thin-film bonding technology. In order to realize a rugged bonding interface between
the semiconductor film and piezoelectric substrate, we studied the 1) optimum
conditions controlling stress in GaAs films, 2) reduction of releasing time for GaAs
films, 3) and enhancement of bonding force between the film and LiNbO3 substrate.
The experimental results clarified that these process improvements were effective for
fabricating functional devices with the AlGaAs/LiNbO3 structure.
Simulation Algorithm for Superconducting Magnetic Levitation System
Authors: Fujii Yusaku , Frantsuz Edmund , Miki Yukinobu , Shiota Fuyuhiko , Khavinson Vladislav
Published: October 2002

A simple calculation algorithm for simulating an axisymmetric Meissner surface has been developed based on Biot and Savart's law, which was originally developed to assist in the design procedure of the next-generation National Research Laboratory of Metrology (NRLM) superconducting magnetic levitation system. Infinitely thin annular filaments represent the floating body covered with lead and the niobium coil. Parameters of the trajectory, such as the magnetic flux link to the coil, \varPhi, the coil current, i, and the vertical displacement of the floating body, Z
0, obtained experimentally and through calculation coincide well with each other. This simulation algorithm can be widely applied for any axisymmetric system of magnetic levitation with coils and Meissner surfaces.
Development of a Versatile Atomic Force Microscope within a Scanning Electron Microscope
Authors: Fukushima Kimitake , Saya Daisuke , Kawakatsu Hideki
Published: October 2002

We have developed a new versatile scanning electron microscope
(SEM)-atomic force microscope (AFM) system capable of simultaneous
SEM and AFM operation. The system consists of a SEM and a detachable
AFM module that can be taken outside of the SEM chamber. By keeping
the height of AFM module to less than 36 mm, and the AFM tip 5 mm
below the highest point of the AFM module, clear SEM image and
variable viewing angle are achieved. The AFM utilizes the
conventional optical lever method. The sample stage of the AFM
module is equipped with remote controlled piezoelectric actuators
enabling three degree-of-freedom positioning with sub-nanometer
resolution and millimeter range. The optical lever path can also be
modified by remote control after the module is placed within the
SEM. The SEM-AFM system can also be used as a tool for micro scale
processing and manipulation by replacing the cantilever with a
designated probe.
Scanning Tunneling Microscopy Study of Surface Reconstructions of Rutile TiO2(111)
Authors: Uetsuka Hiroshi , Sasahara Akira , Onishi Hiroshi
Published: October 2002

Structure of the rutile TiO2(111) surface prepared in
ultra-high vacuum (UHV) was investigated by scanning tunneling
microscopy (STM) and low-energy electron diffraction (LEED) for the
first time. It is expected from the crystal structure that the
stoichiometric TiO2(111) surface has more separated Ti metal
sites compared to the well-studied rutile TiO2(110)
surface. When the surface was annealed at 1024 K in UHV without
Ar+ ion sputtering, a phase indexed as
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Velocity Dependence and Limitations of Friction Force Microscopy of Mica and Graphite
Authors: Yasuo Hoshi Yasuo Hoshi , Takayoshi Kawagishi Takayoshi Kawagishi , Hideki Kawakatsu Hideki Kawakatsu
Published: October 2002

We investigate the behavior of a friction force microscope tip
on a crystal at tip velocities above 1 µm/s.
Cleaved mica and highly oriented pyrolytic
graphite (HOPG) are observed by a friction force microscope
in ambient operation.
A regular saw-toothed signal corresponding to atomic-level stick-slip
is observed in each case at tip velocities lower than 1.5 µm/s.
However,
in the case of observing mica at tip velocities above 1.5 µm/s,
regularity of the signal becomes unstable.
Sometimes no saw-toothed signal is observed
and even if there were a saw-toothed signal,
the pitch of the saw-toothed signal would be larger
than that corresponding to the crystal structure.
In the case of observing HOPG,
clear regularity is detected at tip velocities above 20 µm/s.
The difference is considered to be caused
by the hydrophilic/hydrophobic property of each crystal.
For HOPG,
the mechanical property of the cantilever is the limitation.
For a 200-µm-long and 20-µm-wide rectangular cantilever,
95 kHz and 417 kHz spectrums,
corresponding to the natural frequency of the cantilever
for deflection and torsion with the tip in contact,
start to mask the stick-slip signal as the scanning velocity is increased.
Simultaneous Observation of Ferroelectric Domain Patterns by Scanning Nonlinear Dielectric Microscope and Surface Morphology by Atomic Force Microscope
Authors: Hiroyuki Odagawa Hiroyuki Odagawa , Yasuo Cho Yasuo Cho , Hiroshi Funakubo Hiroshi Funakubo , Kuniharu Nagashima Kuniharu Nagashima
Published: October 2002

A new type of scanning nonlinear dielectric microscope (SNDM), with an additional function of simultaneous observations of surface morphology, has been developed. This was achieved by employing an electrically conducting atomic force microscopy cantilever as a probe needle. Using this new SNDM, simultaneous measurements of several ferroelectric materials, such as lead zirconate titanate (PZT) thin films on both SrTiO3and MgO substrates, were performed. Topographic and domain images were simultaneously obtained from the same location on the materials. Finally, the resolution of the SNDM was theoretically calculated and it was revealed that atomic scale resolution is possible using the SNDM technique.
Origin, Cause, and Electronic Structure of the Symmetric Dimers of Si(100) at 80 K
Authors: Hata Kenji , Kimura Tomohiko , Takeuchi Osamu , Shigekawa Hidemi
Published: October 2002

The characteristics of the apparent symmetric dimers observed in
the scanning tunneling microscope (STM) images at low temperatures
(20K–200K), far below the
symmetric⇔buckled phase transition
temperature, were investigated by utilizing the technique applied to
fabricate an almost defect free Si(100) surface, the art of atomic
manipulation, and current imaging tunneling spectroscopy. We show
that the symmetric dimers are observed at metastable regions caused
by the surrounding defects, and they appear symmetric as a result of
flip-flop motions of buckled dimers.
Surface-State Bands on Silicon –Si(111)-√3×√3-Ag Surface Superstructure–
Authors: Hasegawa Shuji , Sato Norio , Shiraki Ichiro , Petersen Cristian L. , Bøggild Peter , Hansen Torben M. , Nagao Tadaaki , Grey François
Published: October 2002

After reviewing the atomic and electronic structures of the Si(111)-√3×√3-Ag surface, which have recently been clarified after much research, we describe the experimental confirmations of electrical conduction through its surface-state band. A newborn method, micro-four-point probe, is introduced for conductivity measurements with high surface sensitivity.