bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon-Nanotubes for Full-Color Field-Emission Displays
Authors: Choi Won Bong , Lee Young Hee , Lee Nae Sung , Kang Jung Ho , Park Sang Hyeun , Kim Hoon Young , Chung Deuk Seok , Lee Seung Mi , Chung So Youn , Kim Jong Min
Published: October 2002

A 4.5-inch fully sealed carbon-nanotube field-emission display with a
200-µm narrow gap was fabricated on glass using paste squeezing and surface
rubbing techniques. The fabricated displays were fully scalable at low temperatures
below 415°C and showed very high luminance of 1800 cd/m2 at
4 V/µm. The degradation of emission currents for single-wall carbon nanotubes
was less than 10% in electrical aging tests. Large field-enhancement factors and low
turn-on voltages (1.5–3 V/µm) were attributed to well-aligned carbon nanotubes
on substrates and a large number density of carbon nanotubes of 5–10/µm2,
which was confirmed by high-resolution electron microscopy. Although localized states
exist for various tip morphologies, which was calculated by density-functional
tight-binding calculations, the contribution from such states was found to be
negligible.
Characterization of Highly Efficient CdTe Thin Film Solar Cells by the Capacitance–Voltage Profiling Technique
Authors: Yamada Tamotsu Okamoto , Konagai Makoto
Published: October 2002

The electrical properties of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance–voltage (C–V) measurement. According to the dependence of the cell performance on the substrate temperature in the CSS process, the open-circuit voltage (V
oc) increased with increasing the substrate temperature below 630°C. The carrier concentration profiles revealed that the net acceptor concentration exponentially increased from the CdS/CdTe interface to the rear and that the acceptor concentration increased with increasing substrate temperature. This result suggests that V
oc is improved as a result of the increase in the acceptor concentration.
Efficient Noncollinear Second-Harmonic Generation with Proper Frequency Chirp and Tilted Pulse Fronts of Femtosecond Laser Pulses
Authors: Aoyama Makoto , Zhang Tiejun , Tsukakoshi Motowo , Yamakawa Koichi
Published: October 2002

We report on a noncollinear type I second-harmonic generation with tilted pulse
fronts of femtosecond pulses which have a proper frequency chirp in order to
accomplish high energy conversion efficiency. This scheme also enables the generation
of compressed second-harmonic femtosecond pulses simultaneously. We experimentally
demonstrated the increase in energy conversion efficiency from less than 0.4% to
30% with this technique.
A General Multiband Transfer-Matrix Energy-Band Calculation Approach for Two-Dimensional Semiconductor Structures
Authors: Lu Shi-Hsiang , Horng Sheng-fu
Published: October 2002

A general and efficient multiband transfer-matrix method based
on the envelope-function approximation (k·p method) was developed for the calculation of electronic structures of two-dimensional
semiconductor systems. A new searching strategy for the allowed
energy in finite structures was adopted to avoid the generally
encountered divergence problem of the transfer-matrix method across
the classical turning points. A specific continuity condition was
selected to ensure the hermicity of the Hamiltonian
operator. Electric and magnetic fields as well as strain along any
direction can all be included within a unified treatment and at no
further expense in calculation. Examples including the in-plane
dispersion in quantum wells, the influence of strain effects and
electric field on the band structures of quantum wells, and the
minibands in superlattices were calculated to illustrate the use of
this multiband transfer-matrix scheme.
Ab Initio Study of Carbon Nanotubes in Electric Fields
Authors: Kazuhiro Tada Kazuhiro Tada , Kazuyuki Watanabe Kazuyuki Watanabe
Published: October 2002

Electronic structures of four types of carbon nanotubes in an electric field have been investigated by the ab initio pseudopotential plane wave method. The local field enhancement at the tips of nanotubes and the screening of the electric field inside the nanotubes are considerable for nanotubes with a small gap between the highest occupied band (HOB) and the lowest unoccupied band (LUB) in the electronic states. The dangling bond (DB) states near the HOB localized at the edge of nanotubes are significantly influenced by the electric field. Thus, the present results strongly suggest an important role of the localized states of conducting nanotubes with small electronic gaps in field emissions.
Computer Simulation of Direct-Current Field Dependence of the Dielectric Constant of Al2O3-Doped Barium Stronium Titanate in the Paraelectric State
Authors: Chen Yih-Chien , Wu Long , Huang Cheng-Liang , Chou Yi-Ping , Tsai Yuan-Tu
Published: October 2002

Effects of a DC field on the real part of the relative
dielectric constant of Al2O3-doped barium strontium
titanate for application in phased array antennas have been
studied. The real part of the relative dielectric constant of the
specimens decreases when the applied DC field is increased. The
tunability is about 24% for barium strontium titanate doped with 1 wt% Al2O3. Curve fitting only works well for pure barium
strontium titanate. The real part of the relative dielectric
constant of Al2O3-doped barium strontium titanate
decreases rapidly before 1.0 kV/cm and slowly after 1.0 kV/cm when
compared to the data obtained by curve fitting. This can be
explained by the space charge polarization theory.
Difference between Traps Determined from Transient Capacitance and Transient Reverse Current
Authors: Hideharu Matsuura Hideharu Matsuura , Kazushige Segawa Kazushige Segawa , Tatsuya Ebisui Tatsuya Ebisui
Published: October 2002

The densities and energy levels of traps in silicon pin diodes are determined using the transient capacitance method (ICTS: isothermal capacitance transient spectroscopy) as well as the transient reverse current method (DCTS: discharge current transient spectroscopy). The traps determined by ICTS are located in the i layer (i.e., the n- region) and affect the steady-state reverse current (i.e., a generation current). Conversely, the traps determined by DCTS are probably located at the surface of the substrate.
Nanotribology of Clean and Oxide-Covered Silicon Surfaces Using Atomic Force Microscopy
Authors: Contera Won-chul Moon , Tatsuo Yoshinobu Tatsuo Yoshinobu , Hiroshi Iwasaki Hiroshi Iwasaki
Published: October 2002

Atomic force microscopy (AFM) has been used for tribological studies of silicon surfaces both with and without an oxide layer on the surface. Three different types of surfaces were prepared: a silicon surface with a chemical oxide made by the SC1 process, a silicon surface with a thermal oxide, and a H-terminated silicon surface without an oxide layer. Only in the case of the chemical oxide, scratching of the oxide and ploughing of the silicon by the Si3N4 AFM tip were observed. On the other hand, no wear of the sample was noted on the other surfaces. On these surfaces, the AFM often produced elevated patterns in the shape of the scanned area, which were no longer visible after HF etching. The difference between the tribological behavior of the chemical-oxide-covered surface and that of the other surfaces is discussed in relation to the presence of hydroxyl groups in the oxide layer.
Growth and Properties of Transparent Pb(Zn1/3, Nb2/3)O3–PbTiO3 Single Crystals with a Cubic Habitus
Authors: Gentil Sandrine , Robert Gilles , Setter Nava , Tissot Paul , Rivera Jean-Pierre
Published: October 2002

Transparent single crystals of Pb(Zn1/3, Nb2/3)O3–PbTiO3 (PZN–PT) perovskite have been grown by the slow cooling method in a
temperature gradient furnace. The optimization of growth techniques
to crystallize PZN–PT with a cubic habitus is described in
details. The growth temperature range and cooling rates was carried
out in different lead fluxes. Crystal recovery from the residual
flux was obtained by different techniques based on liquid flux
elimination at the end of the growth process. The best transparent
single crystals of PZN–PT, obtained by a cooling at 0.8°C/h from
1150°C to 930°C, had a cubic habitus and a size of
approx.: 4×4×2.5 mm3. The chemical composition and the homogeneity of the crystals were tested by electron probe micro-analysis. Crystals characterization was performed using polarized light microscopy and
dielectric and piezoelectric measurements. Phase transitions were
determined by differential scanning calorimetry, optical and
dielectric measurements.
Observation of Dispersion Behavior of Acoustic Wedge Waves Propagating along the Tip of a Circular Wedge with Laser Ultrasonics
Authors: Yang Che-Hua , Liaw Jiann-Shuoh
Published: October 2002

This research is focused on measuring the dispersion behavior of
acoustic wedge waves propagating along the tip of circular wedges
with a laser-generation/laser-detection laser ultrasound
technique. The unexpected measurement results indicate that the
dispersion relation of the fundamental antisymmetric flexural (ASF)
mode has a negative slope in the phase velocity-frequency dispersion
space for a nearly truncation-free circular wedge. It is also
observed that, at the low-frequency, or long-wavelength limit, the
fundamental ASF mode of the circular wedge has a phase velocity
higher than that of a straight wedge due to the curvature
effect. However, at the high-frequency, or short-wavelength limit,
the fundamental ASF mode of the circular wedge becomes insensitive
to the curvature effect and is dominated by the truncation effect.
Tight-Binding Molecular Dynamics Study of Hydrogen Molecule Inside Silicon Crystal
Authors: Takaba Hiromitsu , Endou Akira , Yamada Aruba , Kubo Momoji , Teraishi Kazuo , Nakamura Kazutaka G. , Ishioka Kunie , Kitajima Masahiro , Miyamoto Akira
Published: October 2002

Tight-binding molecular dynamics simulations were carried out to investigate
the dynamics of a H2 molecule within a silicon crystal using a cluster model. The
global minimum of the H2 molecule's configuration was found to be at the
tetrahedral interstitial site along the <100> direction. This is in good
agreement with the results of first-principles quantum calculations. The H2
molecule was trapped at this site up to a temperature of 600 K. At 900 K, the
H2 molecule diffused into the silicon crystal through the hexagonal site of the
silicon lattice while retaining the H–H bond. These results justify the stability of the
H2 molecule inside the silicon crystal and the possibility of diffusion of the
H2 molecule in the silicon crystal without dissociation.
Formation Mechanism of Multilayer Polyamic Acid Alkylamine Salt Langmuir–Blodgett Films
Authors: Jiro Hamaya Jiro Hamaya , Nobuyuki Wakayama Nobuyuki Wakayama , Mitsutoshi Jikei Mitsutoshi Jikei , Masa-aki Kakimoto Masa-aki Kakimoto
Published: October 2002

In this paper we present atomic force microscopy (AFM) and friction force microscopy (FFM) analyses on the surface structure of mono- and multilayer films prepared from two types of polyamic acid with long alkylamine chains, which were utilized as the precursors of polyimide Langmuir–Blodgett (LB) films. The characteristic domain structures on the monolayer films, namely, the plateau type and the hollow type, were examined while changing the film preparation conditions and the chemical structures of the precursors. The surface structures of the multilayer LB films were also analyzed by AFM, FFM and FT-IR techniques. It was found that the domain structures that appeared on the monolayer film were transformed to a smooth domain-free structure by multilayer deposition of the LB film. The formation and smoothing mechanism of the domain structures was discussed taking into account the fluidity of the polymer groups controlled by the frictional force at the film interface.
Structure of Bi-Dimer Linear Chains on a Si(100) Surface: A Scanning Tunneling Microscopy Study
Authors: Masamichi Naitoh Masamichi Naitoh , Motoki Takei Motoki Takei , Satoshi Nishigaki Satoshi Nishigaki , Nobuhiro Oishi Nobuhiro Oishi , Fumiya Shoji Fumiya Shoji
Published: October 2002

The structure of bismuth-induced Si(100) surfaces has been investigated by scanning tunneling microscopy (STM). Bismuth atoms that adsorb on the surface at 480°C form long linear belts in the Si(100) topmost layer. Each belt consists of two chains of bismuth dimers, and stretches parallel to the ×2 direction of the terrace of the clean Si(100)(2 ×1) surface. From the STM images taken after hydrogen adsorption on the surface, we found that the linear chains of bismuth dimers substitute for four Si-dimer rows on the terrace. We proposed a structural model for the bismuth-dimer chains.
Self-Consistent Particle Simulation of Radio Frequency CF4 Discharge: Effect of Gas Pressure
Authors: Kazuki Denpoh Kazuki Denpoh , Kenichi Nanbu Kenichi Nanbu
Published: October 2002

The dependence of structure of rf CF4 discharge on gas pressure is investigated using the Particle-in-Cell/Monte Carlo method. When the pressure is decreased, the discharge suddenly changes from electronegative to electropositive. For instance, the electron density increases in excess of negative ion density, and double layer and oscillation of bulk electric field disappear. Therefore, joule heating in the bulk disappears, resulting in an abnormally low electron temperature. The high ionization rate in the bulk under low electron temperature can be explained based on the electron energy probability function.
Optimum Discharge Condition of DC Bias Electron Cyclotron Resonance Plasma Sputtering for High Quality Si Epitaxial Growth
Authors: Gao Junsi , Nakashima Hiroshi , Wang Junli , Iwanaga Kanako , Nakashima Hideharu , Ikeda Ken-ichi , Furukawa Katsuhiko , Muraoka Katsunori
Published: October 2002

An electron cyclotron resonance (ECR) plasma sputtering method, combined with
DC substrate bias, has been developed to deposit single crystal thin films at the low
substrate temperature of 400°C and a conventional base pressure of
5×10-7 Torr. At the optimum discharge condition of deposition pressure of
2.2 mTorr and substrate bias of +10 V, with both the ECR power and the rf power
for sputtering of 500 W, crystallographically perfect single crystal deposition was
found to be possible. These results have been interpreted as supplying a sufficient ion
flux to adatoms while maintaining a sufficiently low ion energy to avoid substrate and
film damage during deposition.
Substrate Temperature Dependence of the Surface Reaction Mechanism of Methane Plasma Chemical Vapor Depositon: Experimental and Ab Initio Molecular Orbital Study
Authors: Sato Kota , Cheng Shih-Hung , Haruta Hitoshi , Yokoyama Takashi , Kumashiro Yukinobu
Published: October 2002

A hydrogen detachment reaction which creates sp2 carbons in the surface
processes of methane plasma chemical vapor deposition (CVD) is calculated using an
ab initio molecular orbital method. This reaction is calculated to be kinetically
more favorable than the hydrogen detachment reaction which creates sp3 carbons.
The sp3 formation reaction is thermodynamically more favorable than the sp2
formation reaction. The substrate temperature dependence of the sp2/sp3
ratio and the hydrogen contents of a-C:H films produced by methane plasma CVD are
experimentally studied using Raman and IR spectroscopy, respectively. The substrate
temperature dependence of the reaction mechanism is elucidated on the basis of
calculated and experimental results.
Monte Carlo Simulation of Generations of Continuous and Characteristic X-Rays by Electron Impact
Authors: Fujii Kentaro , Nagatomi Takaharu , Kimura Yoshihide , Takai Yoshizo , Shimizu Ryuichi , Obori Ken-ichi , Yurugi Toshikazu
Published: October 2002

A new Monte Carlo (MC) simulation code has been developed to describe the
spectra of not only continuous X-rays but also characteristic X-rays. The simulation
code is developed using the Kirkpatrick-Wiedmann-Statham equation and the formulae
derived by Casnati and Gryzinski to describe generations of continuous X-rays and
characteristic X-rays, respectively. The results indicate that a series of experimental
X-ray spectra from W films of different thickness on Cu substrates have been
reproduced by the present MC simulation with considerable success. A practical
application for designing the optimum construction of a rotor-type X-ray source is also
presented.
Dry Etching Characteristics of Si-based Materials Using CF4/O2 Atmospheric-Pressure Glow Discharge Plasma
Authors: Kataoka Yoshinori , Kanoh Masaaki , Makino Nobuaki , Suzuki Keiji , Saitoh Shuishi , Miyajima Hiroo , Mori Yoshiaki
Published: October 2002

We etched materials used for semiconductor manufacturing processes,
such as poly-Si films, SiN films, SiO2 films and photoresists, using
atmospheric-pressure glow discharge plasmas, where CF4 gas was
added to the O2 gas in the discharge and downflow regions. High etching rates of
2.3 µm/min for the poly-Si and SiN films, 1.0 µm/min for the SiO2 films and
7.0 µm/min for photoresist were obtained in the discharge region. Furthermore, a reasonably high etching rate of 0.82 µm/min for poly-Si films was also confirmed in the downflow region. The etching characteristics
obtained under atmospheric-pressure glow discharge plasmas and
low-pressure glow discharge plasmas in the discharge region were very
similar. However, in the downflow region, the etching rates of SiN and
SiO2 films were substantially reduced compared to those in the
discharge region. These etching mechanisms were also modeled based on
analytical data and the results of the etching evaluation.
Computer Experiments on Propagation of Nonlinear Waves in Model Crystals with Next-Nearest-Neighbor Atomic Interactions
Authors: Joarder Md. Mahbubul Alam , Minato Atsushi , Ozawa Satoru , Hiki Yosio
Published: October 2002

Molecular dynamics computer simulations were performed for
one-dimensional (1D) and two-dimensional (2D) anharmonic mass-spring
model crystals. Anharmonic potentials up to the fourth order were
taken into account. Central forces were considered between the
nearest-neighbor (nn) and the next-nearest-neighbor (nnn) atoms. The
ratio of the potential between the nnn atoms to the potential
between the nn atoms was varied. An input pulse displacement was
given to definite atoms in the crystal and induced displacements and
velocities of all atoms were computed. Propagating solitons were
produced as atomic excitations and the energy of the excitation was
sharply concentrated in the solitons. Simulations were mainly
carried out to study the influence of interatomic interactions in
the crystal, short-range or long-range in character, upon the soliton
production.
Cepstrum Analysis for Surface Waves on Gels
Authors: Hirotaka Okabe Hirotaka Okabe , Keiichi Kuboyama Keiichi Kuboyama , Kazuhiro Hara Kazuhiro Hara , Shoichi Kai Shoichi Kai
Published: October 2002

Recently, some researchers have revealed the coexistence of capillary and Rayleigh waves on gel.
The coexistence of some waves having the same frequency but different velocities can be confirmed by cepstrum analysis.
Therefore, we examined the applicability of this method to the investigation of surface waves during the gelation process of tungstic acid.
As a result, the coexistence of two waves was confirmed.
The identification of the modes of the two waves will be the subject of a future study.
A Vibration Plate Type Aerial Ultrasonic Sound Source Utilizing Directional Change and Division of Longitudinal Vibrations
Authors: Ito Youichi
Published: October 2002

The author has developed a method for arbitrarily changing the
position and angle of a vibration plate relative to a vibrator in a
flexural vibration plate type sound source (frequency:
approx. 20 kHz) which generates aerial ultrasonic waves in large
capacity. For this method, a vibration transmission rod connected to
a horn was divided into two pieces, and then a device to change the
direction of longitudinal vibrations was installed between the two
pieces. This device was designed so that it can be manufactured and
installed easily. An attempt was made to divide the longitudinal
directions into ones directions using the device. As a result, the
acoustic energy radiated from the sound source was successfully
increased by about two times that of a conventional vibration plate
type sound source.
Two Step Laser Induced Fluorescence: An Enhanced Detection Method of Rydberg-State Species for Electric Field Measurement in Glow Discharge Plasmas
Authors: Kim Jung-Bae , Ikutake Takuya , Bowden Mark D. , Muraoka Katsunori , Czarnetzki Uwe
Published: October 2002

We propose a new laser induced fluorescence scheme aimed at measurement of
electric fields in low pressure discharges. The method uses two
tunable lasers to
excite and de-excite among transitions of atoms. Rate-equation model calculations
and the first experimental results show the proof-of-principle.
Beam Propagation Method for Three-Dimensional Surface Acoustic Waveguides
Authors: Kunimasa Saitoh Kunimasa Saitoh , Masanori Koshiba Masanori Koshiba
Published: October 2002

A beam propagation method (BPM) based on the finite element method (FEM)
is newly formulated for the analysis of longitudinally varying
three-dimensional (3-D) surface acoustic waveguides.
In order to avoid nonphysical reflections from computational window edges,
a transparent boundary condition (TBC) for acoustic waves is proposed.
To show the validity and usefulness of this approach, numerical results
for a Rayleigh-wave beam compressor using Δv/v-type guidance
are presented.
Surface Acoustic Wave Properties of La3Ta0.5Ga5.5O14 Single Crystals
Authors: Onozato Norio , Adachi Masatoshi , Karaki Tomoaki
Published: October 2002

The propagation characteristics of Rayleigh waves on a
La3Ta0.5Ga5.5O14 (LTG) substrate were theoretically investigated
for all cuts and propagation directions. The material constants, such as the elastic
stiffness, piezoelectric constants and their thermal coefficients, were measured by the
resonant and antiresonant frequency method. The existence of orientations with
zero-temperature coefficient of delay (TCD) was calculated by computer
analysis. The electromechanical coupling coefficient (k
2) is about three times
larger than that of ST-cut quartz. The phase velocity is approximately 2690 m/s.
These results indicate a large possibility for application to wide-band
intermediate-frequency surface acoustic wave (SAW) filter devices.
Surface Acoustic Wave Filter Using Floating Electrode Slanted Finger Unidirectional Transducers
Authors: Hiromi Yatsuda Hiromi Yatsuda , Kennichi Noguchi Kennichi Noguchi , Kazuhiko Yamanouchi Kazuhiko Yamanouchi
Published: October 2002

This paper describes a wide-band surface acoustic wave (SAW) filter designed to achieve large stop-band attenuation. The SAW filters using slanted finger interdigital transducers are suitable for mid- or wide-band filters.
To achieve a stop-band attenuation of more than 80 dB, two SAW filters using slanted finger unidirectional transducers (SFUDTs) were cascaded. Since these SFUDT filters have center-to-center distances that differ by one-fourth of the acoustic wavelength at the center frequency, the triple transit echo was effectively compensated. A cascaded-pair SFUDT SAW filter with a fractional bandwidth of 15 percent was designed and fabricated on a 128°Y-X LiNbO3 substrate. An insertion loss of 14 dB, amplitude ripples of 0.5 dB and stop-band attenuation of 80 dB or more were achieved.
Analysis of Piezoelectric Thin Film Resonators with Acoustic Quarter-Wave Multilayers
Authors: Hirofumi Kanbara Hirofumi Kanbara , Hideaki Kobayashi Hideaki Kobayashi , Kiyoshi Nakamura Kiyoshi Nakamura
Published: October 2002

Two configurations of piezoelectric film resonators with acoustic quarter-wave multilayers, which are promising for use in a very high frequency range from 500 MHz to over 10 GHz, are theoretically analyzed using equivalent circuits and the characteristics of the two configurations are discussed with emphasis on their differences. It has been shown that the number of multilayers required for saturation of Q decreases with an increase in the impedance ratio of multilayers and that the effective electromechanical coupling factor has a certain value independent of the layer number. In the λ/4 mode configuration, however, the bottom electrode is located at the strain maximum and therefore the resonator charateristics are influenced by the electrode material. The λ/2 mode configuration appears to be slightly more favorable than the λ/4 mode configuration.
Preparation and Characteristics of Ultrasonic Transducers for High Temperature Using PbNb2O6
Authors: Soejima Junichiro , Sato Kokichi , Nagata Kunihiro
Published: October 2002

The substance PZT(Pb(Zr, Ti)O3) is chiefly used for piezoceramic
transducers in many ultrasonic flow meters. It is difficult to use PZT transducers for
flow meters for automobile exhaust gas at high temperatures over 350°C. Lead
niobate (PbNb2O6) has a high Curie temperature of 540°C and a low
mechanical quality factor, and is the most suitable as the sensor element in flow
meters for automobile exhaust gas. However, it is difficult to fabricate dense
PbNb2O6 ceramics that have good piezoelectric properties. In this study,
ceramics with high density and a high piezoelectric effect were fabricated by adding
various elements such as Mn and Ca to PbNb2O6 and by examining the
sintering process. A Langevin transducer with a resonance frequency of 80 kHz was
made for measuring automobile exhaust gas flow using PbNb2O6 ceramics.
Strain Imaging of a Magnetic Material
Authors: Takata Keiji , Tomiyama Futoshi
Published: October 2002

In this paper we describe a novel method for observing the
domain structure of a magnetic material by strain imaging. When a
magnetic field is applied to a magnetic material, strain is
generated by magnetic forces, electromagnetic interactions, and
magnetostriction. Because the strain has the factors that depend on
the magnetization of each of the domains, we can observe the domain
structure by detecting and imaging the strains using a scanning
probe microscope. We have been successful in imaging the magnetic
domains of a hard disk by lock-in detecting strains induced by an
alternating magnetic field, using an atomic force microscope.
Crystal Growth of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 Using a Crucible by the Supported Bridgman Method
Authors: Harada Kouichi , Hosono Yasuharu , Saitoh Shiroh , Yamashita Yohachi
Published: October 2002

Piezoelectric
Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZNT 91/9)
single crystals with diameters of 40 mm were successfully grown
from solution by the Bridgman method with a PbO flux supported on
the bottom of the crucible. This type of Bridgman method is more
suitable for growing large and heavy crystals than the hanging-type
Bridgman method. Using a modified supporting method, a PZNT 91/9
single crystal was grown. The crystals were grown in a platinum
crucible heated to 1,130°C, and the growth rate was
0.20–0.50 mm/h. The obtained crystals were about 40 mm in diameter×20 mm in length (200 g) and were light
brown in color. The Curie temperature, T
c, ranged from
170 to 175°C. These results confirm that the Bridgman method
using a supported crucible is useful for the mass production of
large crystals of PZNT 91/9.
Model Experiments on Underground Imaging from a Bored Hole by Ultrasound
Authors: Hiroshi Inoue Hiroshi Inoue , Yasuo Yoshida Yasuo Yoshida , Katsuhiko Hayashi Katsuhiko Hayashi
Published: October 2002

The experimental results for seting up of a system to visualize stones in
sand saturated with underground water, using the ultrasonic pulse echo
technique, are described. 1) The speed of sound, 2) transmission efficiency,
3) directivity and 4) sound attenuation, are measured. It is shown that the
profile of the surface of a small stone, about 30 mm in size placed in the sand several centimeters away from the wall of a bored hole can be detected by a
1 MHz ultrasound.
Ultrasonic Power Measurements by Radiation Force Balance Method –Characteristics of a Conical Absorbing Target–
Authors: Kikuchi Tsuneo , Sato Sojun
Published: October 2002

In this study, the authors proposed a conical absorbing target
for ultrasonic power measurements using the radiation force balance
method. We have compared three types of targets, i.e., a conical
reflecting target, a plane absorbing target and a conical absorbing
target. As the result of these experiments, the conical absorbing
target showed some good characteristics for a precise ultrasonic
power measurement system.
Photoacoustic Characterization of Thermal and Electronic Transport Properties of CdInGaS4 in a Transmission Detection Configuration
Authors: Shen Qing , Toyoda Taro
Published: October 2002

Photoacoustic (PA) measurement under a transmission detection
configuration (TDC) was applied to study the thermal and electronic
transport properties of CdInGaS4. It was shown that the PA
signal in the TDC originated from both electronic transport process
and heat transport process in the semiconductor sample, and these
could be separated by changing the modulation frequency of the
excited light. By fitting the theoretically calculated PA signal
amplitudes as a function of the modulation frequence to the
experimental ones for a variety of thicknesses, the values of the
excess-carrier lifetime, carrier diffusivity, surface recombination
velocity, and thermal diffusivity of the CdInGaS4 were
determined. The contributions of three heat sources to the PA
signals were investigated. We found that the PA signals of
CdInGaS4 mainly resulted from nonradiative surface
recombination under our experimental conditions.
The Separation of Multipath Reflection Waves in Water
Authors: Teshima Tetsuro , Kado Akihito , Miyoshi Syuji , Yokoyama Tomoki , Hasegawa Akio
Published: October 2002

In the past, the standing wave method was used to we measure the acoustic
characteristic of underwater objects which includes complex sound pressure
reflectance, a normal-incident absorption coefficient and normal impedance. The
standing wave method is not suitable for performing measurements in a low-frequency
range, because the length of the sound tube should be at least more than one
wavelength. The 2-hydrophone method was proposed to rectify this drawback. But in the
2-hydrophone method, it is necessary to measure the sound velocity precisely.
In this study, we inspect the 3-hydrophone method, where it is not necessary to
measure the velocity of sound in water. We also applied the acoustic intensity method
to separate multipath waves in water. We proved successful separation of multipath
reflection waves using the 3-hydrophone method and the envelope intensity method.
The effectiveness of those methods was verified.
Sea Trial Results of a Cross Fan Beam Type Sub-Bottom Profiler
Authors: Naoi Jun , Ochi Hiroshi , Saito Hideaki , Amitani Yasutaka , Tsuchiya Toshio , Ohyagi Toshio
Published: October 2002

Based on a joint development with SEABEAM Instruments of the U.S., we were the first in the world to develop a cross fan beam type high-resolution narrow beam sub-bottom profiler(SBP) that consisted of a transducer array fitted to a ship bottom. After completion, the resolving power was investigated by targeting a sunken ship, and as a result, the horizontal resolution was estimated to be approximately 3.5 degrees, while the vertical resolution was estimated to be about 2 m. Furthermore, comparison with the parametric high-resolution SBP revealed that the performance of the cross fan beam type SBP was by no means inferior.
Numerical Analysis of Acoustical Propagation Characteristics in Central Equatorial Pacific Ocean with Ridges of Seabed Used by Three-Dimensional Parabolic Equation Method
Authors: Tsuchiya Takenobu , Okuyama Takashi , Endoh Nobuyuki , Nakamura Toshiaki , Nakano Iwao
Published: October 2002

Ocean acoustic tomography (OAT) using sound propagation times in
the ocean is a useful observation system to determine the actual
temperature of water. OAT needs an adequate numerical method of
sound propagation to obtain the prior information about the
ocean. We reported about the wide-angle parabolic equation (PE)
calculation method for long-range propagation. However, if the
ridges on a seabed exist near the SOund Fixing And Ranging (SOFAR)
axis, it blocks sound pulses passing near the SOFAR axis. Sound
pulses are reflected not only in the vertical direction such as sea
surface, but also in the horizontal direction because of ridges of
seabed. Two-dimensional (2-D) analysis of the sound pressure
distribution many have a slight error behind ridges or
islands. Therefore, it is necessary to consider the sound
propagation characteristics using the three-dimensional parabolic
equation (3-DPE) calculation method but the 2-DPE calculation
method. We obtained accurate results for sound pressure distribution
on the SOFAR axis using 3-DPE calculation method, when the sound
pulse was blocked by the seabed. The calculation results of
underwater characteristics by 3-DPE calculation were compared with
those of the 2-DPE calculation method.
Three Dimensional Endoscopic Image of a Blood Vessel Using High Frequency Ultrasound
Authors: Osamu Oshiro Osamu Oshiro , Kumi Kamada Kumi Kamada , Kunihiro Chihara Kunihiro Chihara , Wojciech Secomski Wojciech Secomski , Andrzej Nowicki Andrzej Nowicki
Published: October 2002

This paper describes a high frequency ultrasound (US) imaging system
for observation of small tissues
and a virtual endoscopic image of a blood vessel.
This system consists of a US probe with a central frequency of 32 MHz,
a microscope table
designed to collect some slices of US brightness mode (B-mode) images,
a transmitter containing control logic and a receiver circuit
and a personal computer (PC) with an analog to digital (AD) converter.
First, US B-mode images with high spatial resolution
were obtained by shifting a measurement plane
at a constant step of 0.075 mm.
Second, three-dimensional (3-D) image reconstruction was performed
with linear interpolation and a volume rendering technique.
Finally, the point of view of the 3-D image was set in the human body
and a virtual endoscopic image was presented.
The experimental results present a blood vessel
as if an ultrasound probe were inserted in it
and reveal the anatomical structure under skin.
Development of Magnetic Microbubbles for Drug Delivery System (DDS)
Authors: Soetanto Kawan , Watarai Hiroshi
Published: October 2002

The purpose of this study is to develop a new ultrasonic contrast agent for the
drug delivery system (DDS). Ferromagnetic materials or magnetic carbons were placed
on the surfaces of the surfactant microbubbles developed in our laboratory for the
above purpose. Multivalent ions such as calcium ions were used to place the
ferromagnetic materials or magnetic carbons on the surfaces of the microbubbles.
It was confirmed that the developed magnetic microbubbles could be lead by a
permanent magnet. Furthermore, the performance of the magnetic microbubbles was
evaluated by measuring the time dependence of the attenuation constant as one of their
acoustic properties.
A New Projection Exposure Method Using a Liquid Crystal Display as a Switching Matrix in Place of a Reticle
Authors: Horiuchi Toshiyuki , Miyakawa Tomoki , Hosoda Shinnosuke
Published: October 2002

A new concept of a projection exposure system is proposed. In
the new system, a liquid crystal display (LCD) is used in place of a
conventional reticle, and arbitrary patterns are introduced on the LCD
by a computer keyboard. After investigating what types of LCDs are
suitable, and what exposure contrast is obtained, a prototype test
exposure bench is manufactured using a LCD panel that is detached from
a notebook computer. The bench has a camera lens with F-numbers of
2.8–16 as a projection lens. The LCD dots are of size 263×263 µm2, and each dot includes red, green and blue filter
cells. Patterns on the LCD are replicated onto the wafer on a scale of
1/14.3. It is clarified that a maximum contrast of 4.9 is obtained
when blue and black designations are used as transparent and opaque
cells respectively. Since color LCDs are composed by such red, green
and blue cells, the transparent part cannot be stitched in the lateral
direction. However, in the longitudinal direction, patterns are
stitched quite smoothly, and quasi-arbitrary patterns are replicated
successfully.
Effects of GaP Cap Layer Growth on Self-Assembled InAs Islands Grown on GaP (001) by Organometallic Vapor Phase Epitaxy
Authors: Fuchi Shingo , Nonogaki Youichi , Moriya Hiromitsu , Fujiwara Yasufumi , Takeda Yoshikazu
Published: October 2002

We have fabricated GaP/InAs islands/GaP structures using various
growth sequences for the GaP cap layer, by low-pressure
organometallic vapor phase epitaxy (LP-OMVPE). The effects of the
growth sequences on the buried InAs islands and the GaP cap layers
have been investigated by cross-sectional transmission electron
microscopy (TEM). The two-step growth sequence is effective for the
growth of GaP cap layers, whereby the first GaP layer is grown at
the same temperature as InAs islands and the second GaP layer is
successively grown at the optimized growth temperature of GaP. The
growth sequence yields good-quality GaP/InAs islands/GaP structures
with small InAs islands (15 nm in width and 5 nm in height) and a
high-quality GaP cap layer. Droplet heteroepitaxy of GaP cap layers
is feasible for the control of the size of buried InAs islands.
Peak Width Analysis of Current–Voltage Characteristics of Triple-Barrier Resonant Tunneling Diodes
Authors: Nagase Masanori , Suhara Michihiko , Miyamoto Yasuyuki , Furuya Kazuhito
Published: October 2002

We studied the peak width of current vs voltage (I–V)
characteristics of triple-barrier resonant tunneling diodes (TBRTDs)
experimentally and theoretically. A GaInAs/InP TBRTD was fabricated
by organo metallic vapor phase epitaxy (OMVPE). A theory of I–V
characteristics of TBRTDs was developed by taking the structural
inhomogeneity into account to explain the experimental peak
width. The fluctuation of the well width in a TBRTD grown by OMVPE
was estimated as two atomic layers.
Transmission Electron Microscopy Study by Chemical Delineation in Si Devices
Authors: Back Tae-Sun , Yang Jun-Mo , Park Tae-Soo , Kim Ho-Joung , Lee Soun-Young , Lee Seung-Chul , Choi Jae-Hoon
Published: October 2002

Transmission electron microscopy for a specimen prepared by the chemical
delineation technique in Si devices was carried out in order to investigate the dopant
profiles of ultra-shallow junctions in various regions. The results demonstrate that the
two-dimensional dopant concentration of the junctions can be delineated down to a
level of ∼2.0×1017 cm-3 with a differentiation of As and P dopant
profiles, and can be quantitatively evaluated by comparing the observed and simulated
junction profiles. Furthermore, the morphology of metastable polysilicon formed by
granulating the polysilicon surface and the thickness of the
SiO2–Si3N4–SiO2 dielectric film were clearly observed by
stripping the filled polysilicon by the delineation technique.
Structural and Magnetic Properties of (R1-xYx)1.85Ce0.15CuO4 (R=Pr, Nd, Sm and Eu)
Authors: Meen Teen-Hang
Published: October 2002

(R1-x
Y
x
)1.85Ce0.15CuO4 (R=Pr, Nd, Sm and Eu) have
been investigated by means of X-ray-diffraction and magnetic-susceptibility
measurements. Basically, the lattice parameters a, c, and V decrease linearly
with decreasing ionic radius of R in R1.85Ce0.15CuO4 (R=Pr, Nd, Sm
and Eu), and a pronounced change of the slope at R=Eu is observed. This suggests that
a structural distortion occurs in the R1.85Ce0.15CuO4 series, and the
boundary may lie between Eu1.85Ce0.15CuO4 and
Gd1.85Ce0.15CuO4. Lattice parameters a, c, and the unit-cell
volume V for (R1-x
Y
x
)1.85Ce0.15CuO4 (R=Pr, Nd, Sm and
Eu) decrease with increasing Y concentration x. It is found that the critical
concentration x
c, at which the superconductivity disappears is 0.25, 0.2,
0.15, and 0.0125 for R=Pr, Nd, Sm and Eu in
(R1-x
Y
x
)1.85Ce0.15CuO4, respectively.
In (Eu1-x
Y
x
)1.85Ce0.15CuO4, the magnetic anomaly is
observed at x=0.025, and the magnitude of the anomaly increases with increasing Y
concentration x. Thus the substitution of Y with small ionic radius for Eu plays an
important role on the suppression of superconductivity in
(Eu1-x
Y
x
)1.85Ce0.15CuO4. This provides clear evidence that
the absence of superconductivity in Gd1.85Ce0.15CuO4 is due to weak
ferromagnetism in the Cu–O planes resulting from the too small ionic radius of Gd,
which induces a lattice distortion in the T′ structure.
Narrow-band Stokes Wave Generation and Amplification in a Pulsed Fiber Raman Laser Using a Double-pass Scheme
Authors: Hwang In Duk , Lee Choo Hie
Published: October 2002

We experimentally investigate the narrow-band Stokes generation and its
forward Raman amplification using double-pass fiber Raman scheme which is pumped
by Q-switched Nd:YAG laser. We obtain a variety of narrow-band Stokes lines with the
spectral width less than 0.75 nm within the tuning range of 9.5 nm. The intensity of
amplified Stokes signal can easily be increased by Raman amplification with the
feedback of residual pump pulse.
Low Threshold GaInAsP Lasers with Semiconductor/Air Distributed Bragg Reflector Fabricated by Inductively Coupled Plasma Etching
Authors: Maiko Ariga Maiko Ariga , Yushi Sekido Yushi Sekido , Atsushi Sakai Atsushi Sakai , Toshihiko Baba Toshihiko Baba , Akihiro Matsutani Akihiro Matsutani , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga
Published: October 2002

We fabricated GaInAsP/InP short cavity lasers with semiconductor/air distributed Bragg reflectors (DBRs) by inductively coupled plasma etching with pure Cl2 gas. Nearly vertical sidewalls with low roughness of ∼10 nm were achieved, separated by air spaces of three quarter wavelengths. The lowest threshold current normalized by the stripe width was 3.2 mA/µm. From this value, the DBR reflectivity was evaluated to be 85%, which agreed with the theoretical value obtained from a finite-difference time domain (FDTD) simulation. We compared two types of devices with different DBR shapes, and observed that DBR reflectivity was affected more by the tilt of the DBR sidewalls than the sidewall roughness. This result also agreed well with the FDTD theory.
GaInAsP/InP Multiple-Layered Quantum-Wire Lasers Fabricated by CH4/H2 Reactive-Ion Etching
Authors: Nobuhiro Nunoya Nobuhiro Nunoya , Madoka Nakamura Madoka Nakamura , Hideo Yasumoto Hideo Yasumoto , Shigeo Tamura Shigeo Tamura , Shigehisa Arai Shigehisa Arai
Published: October 2002

GaInAsP/InP multiple-layered quantum-wire lasers with the wire width of 21 nm in the period of 100 nm were realized by CH4/H2 reactive-ion etching followed by slight wet chemical etching and embedding growth by organometallic vapor phase epitaxy. A threshold current density as low as 1.45 kA/cm2 was obtained with the cavity length of 980 µm. To our knowledge, this is the lowest value reported for 1.55 µm GaInAsP/InP quantum-wire lasers fabricated by the etching and regrowth method. Because of the temperature dependence of the lasing wavelength, a relatively large blue shift of 47 meV in the quantum-wire laser was observed, which can be attributed to not only a lateral quantum confinement effect but also a three-dimensional compressive strain effect. Finally, we improved the initial wafer structure in order to suppress over-etching of the active region, and obtained lasers consisting of a five-layered wirelike active region with good size uniformity (wire width of 42 nm, period of 120 nm). A threshold current density as low as 540 A/cm2 was obtained with the cavity length of 1.38 mm.
Laser Oscillation of Energy Transfer Solid-State Dye Laser with a Thin-Film Ring Resonator
Authors: Fukuda Makoto , Mito Keiichi
Published: October 2002

We fabricated an energy transfer solid-state dye laser with a
thin-film ring resonator. We combined several organic dyes, such as
stilbene 3, coumarin 153, rhodamine B, and cresyl violet. The mixed
dyes were embedded into the xerogel thin film by the sol-gel
method. We pumped the dye molecules with a pulsed Nd:YAG laser
third-harmonic generation (THG). Using the mixed-dye doped thin-film
ring resonator, we obtained laser oscillation at four different
wavelengths with one pumping source.
Origin of Infrared Photoluminescence of Nanocrystalline Si in SiO2Films
Authors: Takahashi Hiroshi , Nishimura Toshio , Hashimoto Yusuke , Takahashi Shinichi , Kuwano Hiroshi
Published: October 2002

Si+implanted SiO2films subjected to high-temperature annealing exhibit a broad-band infrared luminescence. In order to reveal the origin of the infrared luminescence, we investigate the structure and the luminescence property of Si+implanted SiO2films by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) and cathodoluminescence (CL) measurements. The experimental results of FTIR and XPS measurements show that nanosized Si particles, which are responsible for the infrared luminescence, are formed in SiO2films by thermal annealing at 1100°C. It is found that there is no significant difference between PL and CL spectra with excitation energy, and that the infrared CL spectra do not change with temperature. These results support the idea that the infrared luminescence is related to the defect states at the interface between nanocrystalline Si and SiO2films.
Study of Internal Electric Field of Liquid-Crystal Cell Effected by Space-Charge Polarization
Authors: Sawada Atsushi , Sato Hiromoto , Manabe Atsutaka , Naemura Shohei
Published: October 2002

The distribution of the local electric field in a liquid-crystal cell containing
mobile ions was simulated in accordance with the Poisson equation in the steady state
under a DC voltage application. The distribution of the local field was determined to be
markedly unbiased due to the contribution of the bound charges on the electrodes
induced by ions. This result suggests that the intensity of the local field acting on ions
can be approximated by that of the external field, for analyzing the space-charge
polarization under a small AC voltage application even in a very low frequency region,
where the diffusion distance of ions during the period of the external AC field becomes
greater than the thickness of the cell.
Improvement of Properties of SrTiO3 Thin Films Deposited at Low Temperature and High Rate by Sputtering Gas
Authors: Kohara Naoki , Yoshida Akihisa , Sawada Taisuke , Kitagawa Masatoshi
Published: October 2002

SrTiO3 thin films have been prepared by RF magnetron
sputtering at a low substrate temperature of 200°C and a high
deposition rate of 35 nm/min on Al/glass substrates. X-ray
diffraction data indicated that deposited SrTiO3 thin films
were partially polycrystalline and/or amorphous. The properties of
SrTiO3 thin films were improved by sputtering gas. As the mass
of the sputtering gas was light, the signal intensity ratios of
Ti/Sr in the optical emission spectra increased, and surface
protrusions were suppressed. In particular, in the presence of
N2 gas, the properties of SrTiO3 films were improved, and
the leakage current density and tan
δ markedly
decreased. SrTiO3 film of 300 nm thickness exhibited the
dielectric properties with a relative dielectric constant of 62 and
a leakage current of 4×10-10 A/cm2 at a voltage of +5 V, and tan
δ of 0.6% at 1 kHz.
A Study on Thyratron Ranging and Diagnosis
Authors: Han Y. J. , Nam S. H. , Park S. S. , Kim S. H. , Lee K. T. , Park S. W. , Cho M. H. , Lee Eui-Wan
Published: October 2002

Thyratrons have been used as switching tubes in power conditioning systems, primarily for radar and accelerator applications. Their function are to control power pulses to high-frequency oscillators in high-power radar sets, lasers, and other communications equipment. However, it is difficult to diagnose the switching characteristics of the thyratron. From a convection heat transfer, we have discovered the diagnostic factor of the thyratron, where the variation of the heater current occurs according to the variation of the internal gas pressure. By this diagnostic factor, thyratron ranging and diagnosis are possible. We have verified the theoretical propriety of the diagnostic factor and confirmed that the assumption used in the theory is applicable to the thyratron.