bluuebunny/crossref_metadata_2025 huggingface dataset:
Emission Profile Dependence of Microcavity Light Emitting Diodes
Authors: Pratt Andrew Richard , Takamori Takeshi , Kamijoh Takeshi
Published: October 2002

Data are presented to show the variation in the emitted radiation pattern of
semiconductor microcavity light emitting diodes (MC-LEDs) with different cavity mode
de-tunings. Compared to a conventional non-cavity LED structure, a narrow single-lobed
emission profile is only observed when the cavity mode is de-tuned greater then 15 nm
below the bare quantum well peak. For positively de-tuned MC-LEDs, the beam
divergence broadens, and the far-field emission profiles exhibit a double-lobed
emission pattern, which is sensitive to the pump level.
Control of Surface Oxidation Layer Thickness in Metal Evaporated Tapes
Authors: Yoshida Osamu , Nagai Satoshi , Kitaori Noriyuki , Ishikawa Akira
Published: October 2002

The formation mechanisms of the surface oxidation layer and the
oxidation inside metal evaporated tapes have been clarified. The
Auger depth profiles of the samples deposited with various geometric
arrangements of the oxygen gas flow nozzle were investigated. The
surface oxidation layer is influenced by the oxygen partial pressure
distribution around the can roll near the nozzle. The internal
oxidation of the film is caused by the diluted oxygen gas after
diffusion around the can roll. The results suggest that oxygen gas
heating will cause a reduction in the thickness of the surface
oxidation layer. The introduction of high-temperature metal vapor
and radiant heat into the nozzle is effective in decreasing the
thickness of the surface oxidation layer and significantly improves
the playback output levels, particularly at short recording wavelengths.
Subtarget Effect on Laser Plasma Generated by Transversely Excited Atmospheric CO2 Laser at Atmospheric Gas Pressure
Authors: Kagawa Kiichiro , Lie Tjung Jie , Hedwig Rinda , Abdulmajid Syahrun Nur , Suliyanti Maria Margaretha , Kurniawan Hendrik
Published: October 2002

An experimental study has been carried out on the dynamical process taking place
in the laser plasma generated by Transversely Excited Atmospheric CO2 laser
(100 mJ, 50 ns) irradiation of a soft sample at surrounding helium pressure of
1 atm. It is shown that the presence of a copper subtarget behind the soft sample is
crucial in raising the gushing speed of the atoms to the level adequate for the
generation of shock wave laser plasma even at atmospheric pressure. It is also found
that the time profiles of spatially integrated emission intensity of the target's atoms
and gas atoms exhibit a characteristic dynamical process that consists of successive
excitation and cooling stages even at such a high pressure, which is typical of shock
wave laser plasma. It is therefore suggested that the generation of the laser plasma at
atmospheric pressure is more likely due to the shock wave mechanism than to the
widely known breakdown mechanism. Initial spectrochemical analysis of water from
the blow off of a boiler system was also carried out, showing a detection limit of as
low as 5 ppm for calcium.
Structure and Refractive Indices of Proton-Implanted LiNbO3
Authors: Atuchin Victor V. , Nagata Hirotoshi , Kawamura Ken-ichi , Higuma Kaoru , Ichikawa Junichiro , Pokrovsky Lev D. , Takai Hiroshi , Hosono Hideo
Published: October 2002

Structural damage is found in -c-cut LiNbO3 single-crystal surfaces
in which 1×1017 cm-2 protons are implanted. The observed damage is
accompanied by a large decrease in the ordinary-ray refractive index, n
o,
which falls to the same level as the extraordinary-ray refractive index, n
e.
The mechanism of the phenomenon can be explained by disordering in the implanted
layer.
New Ferroelectric Ba5Ti2O7Cl4
Authors: Ingle S. G. , Patil N. M.
Published: October 2002

A new crystalline material grown by the flux method and
identified chemically and through density and structure
determination as Ba5Ti2O7Cl4 has been
synthesized, and is shown to possess ferroelectric properties. The
structure is found to be orthorhombic at room temperature using
powder method of X-ray diffraction. The lattice constants at room
temperature are a=8.526 Å, b=7.608 Å and
c=11.696 Å with an uncertainty of ±0.0025 Å. The
crystal has a space group Pmc21, and the atomic positions are
shown to confirm with the observed X-ray reflection intensities. It
is found that two lattices related to each other by the interchange
of a and b axes describe the crystal structure, and the X-ray
intensities can be explained by considering the ions present on both
the lattices for a given (h
k
l) plane. The use of the atomic
scattering factors available in literature give the correct X-ray
intensities, if the microstructure present in the crystal in the
form of pronounced twinnings on planes (100), (200),
(010), (020), (001), (020), (110),
(220) is taken into account. The calculations are done using
trial and error method anticipating the atomic positions.
Dielectric Properties of (Ba1-xCex)TiO3
Authors: Hwang Jin Hyun , Han Young Ho
Published: October 2002

Ce substitution for the Ba site shifted the Curie point to a lower temperature than typical substitution with elements such as Zr and Sr. The substitution of Ce for the Ba sites up to 2.0 mol% exhibited a typical donor-doped behavior, the material being fine grained and of depressed dielectric constant at the Curie point. The specimens doped with more than 2.0 mol% CeO2 had relatively high dielectric constant at the Curie point. The increase in dielectric constant at the Curie point seems to be correlated with the grain size. Dielectric properties and microstructure development of highly Ce-doped BaTiO3 are discussed in terms of defects in the cation sublattice.
Application of a Circularly Homogeneously Aligned Liquid-Crystal Cell to Real-Time Measurements of Twist Angles in Twisted-Nematic Liquid-Crystal Cells
Authors: Michinori Honma Michinori Honma , Rumiko Yamaguchi Rumiko Yamaguchi , Susumu Sato Susumu Sato
Published: October 2002

A novel system which employs a pair of circularly homogeneously aligned liquid crystal cells (CH-LC cells) for measuring the time-dependent twist angles of twisted- nematic liquid crystal (TN-LC) cells is proposed. A unique polarization-converting property of a CH-LC cell is discussed. A scheme of calculating the twist angle is derived by the Jones matrix. The applicability of the proposed system is confirmed by measuring the time-dependent twist angle of a TN-LC cell with partially saponified polyvinyl alcohol (PVA) films in real time. Two factors, on which the measurement accuracy depends, are discussed: deviations of the polarizer and the analyzer from both x and y-axes and the resolution of the measured transmission image. The measurement accuracy in this paper is estimated to be within about 1°.
Surface Roughness of Hydrogen Ion Cut Low Temperature Bonded Thin Film Layers
Authors: Li Y. Albert , Bower Robert W.
Published: October 2002

We have observed that wafer splitting from hydrogen ion implantation into silicon after
low temperature direct bonding creates an expunged film with a surface roughness that is
∼1 nm (RMS). This result is an order of magnitude smoother than the previous work
(∼10 nm RMS). The key improvement is the use of low temperature bond in our work
resulting in a strong bond far below the cut temperature. The smooth as-split surfaces
produced using a low temperature bond are very important for creation of very thin
(<50 nm) silicon-on-insulator (SOI), three-dimensional bonded structures and nanostructures that are split after
processing.
Ion Transport Analysis by Extended Wannier Theory: II. Effect of Ion Density Gradient in the Transverse Direction
Authors: Kondo Yoshitaka , Yamada Tadahiko
Published: October 2002

In this paper, Wannier's integral-differential equations derived from the Boltzmann equation in the cases of cold gas were extended to cases having density gradients in the transverse direction. Velocity distributions of an ion swarm were obtained by solving these equations numerically. The mobilities and diffusion coefficients obtained from these velocity distributions coincided with those obtained previously by Monte-Carlo simulation.
Pressure Effect on the Formation of Ferroelectric SrBi2Ta2O9 Thin Films
Authors: Song Kang Yong , Lee Yong Kyun , Lee Kyu Sang , Yoon Yung Sup , Chae Hee Kwon , Lee Wan In
Published: October 2002

It has been found that the formation of a ferroelectric phase
for the SrBi2Ta2O9 (SBT) thin films derived from
sol–gel solution is dependent on the oxygen pressure during the
heat-treatment process. Under an elevated oxygen pressure as high as
30 atm, the heat-treatment temperature inducing the ferroelectric
SBT phase can be lowered to 650°C. Those films processed at
650°C present satisfactory ferroelectric properties, that is,
the remanent polarization (P
r) is 5.0 µC/cm2,
and the coercive field (E
c) is 43 kV/cm with 5 V
application.
Growth Sector Dependence of Low Frequency Raman Peaks Observed in Boron-Doped Homoepitaxial Diamond Particles
Authors: Wang Yuguang , Li Hongdong , Lin Zhangda , Feng Kean
Published: October 2002

The Raman spectra of boron doped homoepitaxial diamond particles
are investigated. The low frequency parts of the Raman scattering
spectra of (100) and (111) growth sectors are very different in peak
numbers and in peak positions. (100) facet has three broad bands
centered at 580, 920 and 1020 cm-1, (111) facet has only two
centered at 500 and 1180 cm-1. These low frequency peaks
originate from Raman scattering by phonons far from the center of
the Brillouin zone. Electronic Raman scattering may also contribute
to part of the Raman spectra.
Oxygen Induced Enhancement Effects in Optical Emissions from a FeNi Target by Kr+ Ion Bombardment
Authors: Agarwal P. , Bhattacharyya S. R. , Ghose D.
Published: October 2002

The light emission from a polycrystalline FeNi alloy by 6 keV Kr+ ion beam sputtering in presence of oxygen has been studied. Measurements of decay features in spectral lines of Fe I and Ni I indicate that there is a preferential oxidation of Fe in oxygen ambient substantiating the results obtained by other surface analytical techniques. The present experiment illustrates the possibility of using bombardment-induced light emission spectroscopy as a complementary technique for analysis of relative oxidation states of the elements on the surface of the compound targets.
Effects of Illumination on Thermionic Energy Converter Characteristics
Authors: Zheng Wei , Ogino Akihisa , Kando Masashi
Published: October 2002

The thermionic electron current density J
e from hot tungsten in a
cesium atmosphere has a maximum at emitter temperatures T
E lower than
1400 K and a cesium gas temperature T
Cs of around 500 K. Solar light
can excite or ionize cesium atoms because of the atom's low excitation and ionization
potentials. These phenomena can be applied to the development of a novel thermionic
energy converter (TEC) using exclusively solar light or operated at a low T
E
together with other heat sources. In the present work, the effect of illumination of a
xenon lamp with a broad spectrum similar to solar light is examined from the viewpoint
of the improvement of low T
E TEC. It is found that illumination can
improve TEC characteristics under the conditions that 1) space charge neutrality
α<10-2, 2) thermionic electron current density
J
e>10-3 A/cm2 and 3) the emitter work function
φE>2.2 eV. These conditions ensure negative space potential
formation in TEC. Electrons produced in the potential well by illumination can be
accelerated at the electron sheath near the collector and ionize cesium atoms. As a
result, illumination can accelerate the transition to the ignited mode and/or increase
the TEC output current.
High-Current Pulsed Power Generator ASO-X Using Inductive Voltage Adder and Inductive Energy Storage System
Authors: Kohno Susumu , Teramoto Yusuke , Lisitsyn Igor V. , Katsuki Sunao , Akiyama Hidenori
Published: October 2002

A novel pulsed power generator using inductive voltage adder technology has been
put into operation in Kumamoto University. This machine, named “ASO-X”, is an
inductive voltage adder-inductive energy storage pulsed power system. The maximum
output voltage and current of ASO-X are 180 kV and 400 kA, respectively, into a short
circuit load with a current quarter period of 1.3 µs. In order to increase the
voltage and power and to decrease the rise time of the load current, a plasma opening
switch is used at the output of ASO-X. Eight plasma guns serve as the plasma source
for the opening switch in a circuit with a single triggered spark-gap switch. This
system provides a very fast current rise rate (3.6×1012 A/s) and over
1 µs of conduction time of the plasma opening switch.
Bending Machine Using Anisotropic Polypyrrole Films
Authors: Tetsuya Okamoto Tetsuya Okamoto , Kazuya Tada Kazuya Tada , Mitsuyoshi Onoda Mitsuyoshi Onoda
Published: October 2002

We have found that a polypyrrole (PPy) film with anisotropy of conductivity and morphology bends in a regular direction and reverts during redox cycles. That is, the anisotropic PPy film acts as an actuator or a “bending machine”. The PPy film can be prepared electrochemically as a fiber in a slender Teflon pipe. The response speed of the PPy fiber actuator depends on the speed and amount of dopant insertion and extraction; namely, it becomes faster when the reduction potential is more negative or the electrolyte concentration is higher. The bending behavior strongly depends on the type of supporting salt in the electrolyte solutions, suggesting that cation transport into and out of PPy plays a key role in the bending behavior and that the size of the cation is also a critical factor. A bending behavior mechanism based on cation insertion and extraction, as well as on the anisotropic volume change upon doping/undoping, is proposed.
Effects of Gas Temperature Gradient, Pulse Discharge Modulation, and Hydrogen Dilution on Particle Growth in Silane RF Discharges
Authors: Masaharu Shiratani Masaharu Shiratani , Shinichi Maeda Shinichi Maeda , Kazunori Koga Kazunori Koga , Yukio Watanabe Yukio Watanabe
Published: October 2002

The effects of gas temperature gradient, pulse discharge modulation, and hydrogen dilution on the growth of particles below about 10 nm in size in silane parallel-plate RF discharges are studied using a high-sensitivity photon-counting laser-light-scattering (PCLLS) method. Thermophoretic force due to the gas temperature gradient between the electrodes drives neutral particles above a few nm in size toward the cool RF electrode which is at room temperature. Pulse discharge modulation is much more effective in reducing the particle density when it is combined with the gas temperature gradient, and particles above a few nm in size cannot be detected by the PCLLS method even after 2 h. Hydrogen dilution of a high H2/SiH4 concentration ratio above about 5 is also useful in suppressing particle growth in the radical production region around the plasma/sheath boundary near the RF electrode.
Proposal of a New Model on Behavior of GHz Phonon Fluxes Amplified from Thermal Phonons in Piezoelectric Semiconducting n-CdS
Authors: Tokunaga Yoshiaki , Kugo Yukio
Published: October 2002

The purpose of this study is to propose a new model wherein the piezoelectric
semiconducting n-CdS is recognized as a kind of complex system based on the
interaction among an electron, an amplified flux and a thermal background noise in a
piezoelectric field. In this model, the system metamorphoses drastically from the
thermal equilibrium state in an isolated system into a “far-from-equilibrium state of
turbulent chaos” in an open system when an external high voltage is applied to the
CdS. The dynamics of the amplified flux is simulated by a time-evolutional
differential equation (similar to a logistic equation) composed of the White theory, the
Akhieser damping theory, and the Ozaki-Mikoshiba theory. The simulation result agrees
qualitatively with experimental evidence on the flux distribution in the case of a
slow-rise-time pulse application.
Influence of the Insertion of a Solid Plate on the Second Harmonic Component of a Focused Beam
Authors: Saito Shigemi
Published: October 2002

The nonlinearly generated second harmonic component in a focused
sound beam detected by a concave receiver placed beyond a solid
plate, has been analyzed theoretically and experimentally. The
amplitude and phase of the fundamental and second harmonic
components in the focused sound are significantly affected by the
plate thickness and driving frequency as well as the acoustic
property of the plate. Primarily due to the second harmonic
generation after the transmission through the plate, the influence
of the insertion of the plate on the magnitude of the nonlinear
second harmonic signal differs significantly from that on the
magnitude of the linear fundamental or double-frequency sound. This
causes the difference of contrast in the nonlinear image from that
in the linear image obtained with a transmission-type acoustic
microscope.
Ultrasonic Properties of a Binary System of a Soluble Protein, α-Lactalbumin and Dimyristoyl Phosphatidylcholine Membrane
Authors: Sakai Hiroko , Imai Kenichiro , Tanaka Michiko , Sonoyama Masashi , Mitaku Shigeki
Published: October 2002

The interaction between a soluble protein α-lactalbumin
(α-LA) and dimyristoyl phosphatidylcholine (DMPC) liposomes
was studied using an ultrasonic technique. The ultrasonic properties
of DMPC liposomes changed significantly after the addition of
α-LA at pH 3. The lipid bilayer transition temperature became
higher and transition anomalies of DMPC liposomes were enhanced in
the presence of α-LA under these conditions. At the same
time, the size of the liposomes apparently decreased as revealed by
the clearing of suspensions.
A Simple Nondestructive Evaluation of an Adhesive Layer Using Elastic Wave Velocities
Authors: Matsukawa Mami , Nakayama Shuhei , Ohtori Norikazu
Published: October 2002

A curing process of epoxy adhesive layers has been investigated
by an ultrasonic pulse spectroscopy and a Brillouin scattering
technique. Observed longitudinal elastic wave velocities in the
curing layer depended on the velocity in the prepolymer used. From
this result, we suggest a simple nondestructive method for the
estimation of sample T
g (glass transition temperature) during
cure. The estimated T
g values were in good accordance with the T
g values measured by differential scanning calorimetry.
Utilization of Ultrasonic Energy in a Photocatalytic Oxidation Process for Treating Waste Water Containing Surfactants
Authors: Suzuki Yasuyuki , Maezawa Akinori , Uchida Shigeo
Published: October 2002

A system for treating waste water containing surfactants using a
photo-oxidation catalyst combined with ultrasonic irradiation was investigated. The
system consisted of two reaction chambers installed with ultrasonic transmitters of
different frequencies to enhance the photo-catalytic reaction as well as to recover the
photocatalyst particles used. An ultrasonic transmitter with a frequency of 200 kHz
was used the reaction to enhance in the first chamber. An ultrasonic transmitter with a
frequency of 28 kHz was installed for particles recovery in the second chamber. Glass
beads (hereinafter GB) were used as the collectors as well as the accelerators of the
agglomerated photocatalyst particles under ultrasonic irradiation. Waste water
containing a surfactant, i.e., polyoxy-ethylene-alkyl-ether
(C14H29O(CH2CH2)7H, hereinafter SS-70) with an initial
concentration of 100 ppm and a volume of 1000 ml was used as a sample. It was
confirmed that after three times of recycling tests there was no significant loss in
catalyst activity.
Sonophotocatalytic Reaction of Sodium Chloride Solution: Comparison of Reaction Products from Sodium Chloride Solution with Those from Pure Water and Influence of Insoluble Photocatalyst on Sonochemical Reaction
Authors: Harada Hisashi
Published: October 2002

A sonophotocatalytic reaction of NaCl solution was
performed. Hydrogen and oxygen were obtained continuously. A
sonophotocatalytic reaction is a photocatalytic reaction with
ultrasonic irradiation or the simultaneous irradiation of light and
ultrasound with a photocatalyst. The higher the concentration of
NaCl in a solution, the lower the amount of products
obtained. However, there was negligible influence on the products at
lower concentrations. Therefore, it was concluded that the
impurities such as chloride ions, from the photocatalyst had
negligible effect on the sonophotocatalysis of water. It was also
demonstrated that a suitable photocatalyst particle size must be
selected for the sonophotocatalytic reaction to proceed. The
possibility of decomposition of seawater to H2 and O2 was
also examined.
Welding Characteristics of Ultrasonic Seam Welding System Using a Complex Vibration Circular Disk Welding Tip
Authors: Tsujino Jiromaru , Ueoka Tetsugi
Published: October 2002

The continuous welding characteristics of a 27 kHz ultrasonic seam welding
system using a complex vibration circular disk welding tip are studied. The vibration
characteristics of a complex vibration converter were improved compared with the
prototype model. The circular disk welding tip vibrates in both transverse and torsional
vibration modes and an elliptical vibration locus is obtained at the circumference of
the circular disk welding tip. An ultrasonic seam welding equipment consists of a
complex vibration circular disk welding tip that is driven by a longitudinal vibration
system through a longitudinal-torsional vibration converter, and an automatic specimen
shifting stage. A large number of aluminum plate specimens of 0.3 mm to 0.5 mm
thickness and 50 mm to 300 mm length were continuously joined to a thick aluminum
plate at multiple welding parts.
Photoresponse on Surface Acoustic Wave Devices with Compound Semiconductor and LiNbO3 Structures
Authors: Kaneshiro Chinami , Suda Takaya , Aoki Yusuke , Hong Chulun , Koh Keishin , Hohkawa Kohji
Published: October 2002

We studied the photoresponse on a surface acoustic wave (SAW) device coupled
with AlGaAs film. The experimental results indicate that the transferred carriers by
SAW are optically generated electrons rather than optically generated holes. The
electric field due to SAW propagation reduces the recombination of the optically
generated electrons and holes. We were able to observed a modulated SAW signal due to
the nonlinear interaction between SAW and optically induced carriers. The
photoresponse due to the interaction between SAW and optically induced carriers shows
a high sensitivity for the light intensity. The main results are (1) the control of SAW by
optically induced carriers, and (2) the control of the optically induced carriers by
SAW. We expect that the characteristics of the photoresponse will be applicable to
the fabrication of functional optical-SAW coupled devices.
Quasi–Lamé–Mode Quartz–Crystal Resonators
Authors: Yasutaka Shimizu Yasutaka Shimizu , Masao Murota Masao Murota , Hirofumi Kawashima Hirofumi Kawashima , Yukio Yokoyama Yukio Yokoyama , Tadayoshi Kubota Tadayoshi Kubota
Published: October 2002

In this paper, quasi-Lamé-mode quartz-crystal resonators formed by
etching processes are examined theoretically and experimentally.
First, the frequency equation for a Y-plate quartz-crystal resonator is
derived by the energy method.
Then, the relationship between the cut angles φy and θy to
vibrate the quasi-Lamé mode is investigated.
There are many combinations of φy and θy for which the
first-order temperature coefficient α becomes zero.
Finally, it is theoretically and experimentally demonstrated that the
temperature characteristics of a Y-plate quasi-Lamé-mode quartz-crystal
resonator is superior to that of a pure-Lamé-mode resonator.
Twinning of a Quartz Plate at Low Temperature Using a Laser Beam
Authors: Satoru Noge Satoru Noge , Takehiko Uno Takehiko Uno
Published: October 2002

We have previously reported an artificial twinning (x-axis
inversion) technique that involves the thermal treatment method and
the laser beam scanning method for a rotated Y-cut (RY-cut) quartz
plate. The heating temperature for twinning was
about 520–540°C using the thermal treatment method.
Furthermore, in the laser beam scanning method, a high preheating
temperature of about 480°C was necessary to obtain a
well-controlled twinning pattern. We present here twinning at low
temperature (350°C ∼ room temperature) using the laser beam
scanning method. This method can be used the potential to form an arbitrary
fine twinning pattern at room temperature. High reproducibility of a fine
twinning pattern was obtained at a preheating temperature of
350°C. A relatively good twinning pattern was also obtained by the
laser beam scanning method without preheating. It was estimated that the
shear strain caused by laser irradiation was of the order of 10-4, for
the case there the twinning occurred. The large temperature gradient
produced in the plate by laser beam irradiation drastically reduced the
treatment temperature.
Temperature Distribution in Circular Space Reconstructed from Sampling Data at Unequal Intervals in Small Numbers Using Acoustic Computerized Tomography (A-CT)
Authors: Akira Funakoshi Akira Funakoshi , Koichi Mizutani Koichi Mizutani , Keinosuke Nagai Keinosuke Nagai , Ken'ichi Harakawa Ken'ichi Harakawa , Tomoki Yokoyama Tomoki Yokoyama
Published: October 2002

The propagation velocity of sound is often used to measure temperature. The sound probe has the advantage of non-contact sensing and quick response. By combining a sound probe with computerized tomography (CT) and data interpolation, an image of temperature distribution through space can be reconstructed. We have proposed a method for measuring the temperature distribution in two-dimensional space using an acoustic CT (A-CT) method with a very small number of acoustic transducers. The measured object is a circular space with a radius of 1,480 mm. Sixteen transducers are installed on the circular stage. Without a mechanical motion, projection data for the reconstruction is acquired by electronic scanning.
We reconstruct the temperature distribution by interpolation from a small number of data set. Electrical heaters create a temperature gradient in space. The temperature profile is measured by 19 thermocouples and used for a computer simulation. Experimentally reconstructed images are in agreement with the simulated images. The measurement system proposed in this paper has advantages for use in atmospheric monitoring, air conditioning and heat management.
Study on the Optimal Distance between the Sand Surface and the Sensors Array for the Measurement of Sand Moisture
Authors: Takano Nobuyuki , Fujimoto Masao , Tao Liang , Motooka Seiichi
Published: October 2002

A method of discriminating the moisture content of sand by
neural-network data processing using the ultrasonic pulse-echo
signals received by receivers in a parabolic transmitter-receiver
array was proposed in our previous work. The stability of the signal
received was not satisfactory, however, and the final discrimination
ratio of sand moisture was low at some points. To achieve a
reflected signal with higher signal to noise ratio, this study
examined the optimal distance between a newly arranged
transmitter-receiver array and the surface of the moist sand. The
theoretical estimation and the experimental results of pressure of
received sound versus distance show a similar tendency. The optimal
distance is determined by analyzing the theoretical and experimental
results. The comparison of the distribution of received data and the
discrimination ratio verify that the stability of the discrimination
in the new optimal arrangement is improved.
Feasibility Study of Grain Size Estimation of S45C by Attenuation Measurement of 40 MHz Surface Acoustic Wave Generated by Phase Velocity Scanning of Laser Interference Fringes
Authors: Nishino Hideo , Furukawa Tsutomu , Takashina Sunao , Takemoto Mikio
Published: October 2002

Structural change in 0.45 mass % carbon steel during tempering
was measured nondestructively as a change in the attenuation
coefficient of 40 MHz surface acoustic waves (SAW) generated by
scanning interference fringes (SIF). The SIF selectively generate
the SAW at an adequate center frequency, which is useful to
distinguish the attenuation coefficients between slightly different
structures. The attenuation coefficient at 40 MHz increased
linearly with heating time (30, 60 and 90 min) at 750°C,
representing a minute change in the structure of ferrite and
pearlite grains. The method revealed a minute structural change in
the ferrite-pearlite ratio and in grain size growth due to the heat
treatment.
Characterization of Electronic States of TiO2 Powders by Photoacoustic Spectroscopy
Authors: Toyoda Taro , Kawano Hiroshi , Shen Qing , Kotera Akihiko , Ohmori Masahiro
Published: October 2002

We have measured the optical absorption of TiO2 powders by
photoacoustic (PA) spectroscopy, which is powerful for detecting
small amounts of strongly scattering materials. The band-gap
energies E
g of rutile and anatase types of TiO2
powders with particle radii of 40 nm are 3.06 eV and 3.20 eV,
respectively, from PA intensity and PA phase spectra, indicating the
usefulness of PA spectroscopy. The PA intensity and phase spectra
show that the E
g of anatase-type TiO2 powders with
a particle radius of 11 nm is 3.25 eV (blue shift) within the
experimental accuracy, indicating the possible onset of a quantum
size effect with decreasing particle size. The PA intensities
plotted semilogarithmically vary linearly with photon energy
immediately below the band-gap, in accordance with Urbach's rule
(exponential tail). The slope of the exponential absorption of
rutile-type TiO2 powders is larger than that of the anatase,
indicating that the anatase-type has increasing energy from the
displacement of atoms specifically due to oxygen vacancies and/or
chlorine impurities in the production processes of the powders.
A New Calculation Method of Radiation Impedance for Vibrating Surfaces with an Arbitrary Shape
Authors: Kim Moo-Joon , Kim Chun-Duck , Ha Kang-Lyeol
Published: October 2002

We have investigated a calculation method of obtaining self- and
mutual-radiation impedance for a square vibrating surface by computing the mutual
radiation effects between each of the elements, in which the square vibrating surface
was considered to be an aggregation of infinitesimal square vibrating elements. In this
study, by extending this method, we derived a useful equation to calculate the
self-radiation impedance for a vibrating surface with an arbitrary shape that can be
represented by a set of subsquares. An algorithm to determine the number of identical
results is derived and used to reduce the computation time. The validity of the equation
for the arbitrary shape is verified by applying it to a square surface consisting of four
subsquares, and the result agrees with that of the single large square surface. As
examples of arbitrary shapes, the self-radiation impedance for vibrating surfaces with
the shape of letter “L” and of a spiral are obtained.
Experiments for Acoustic Digital Data Communication Using Frequency Shift Keying Modulation
Authors: Ochi Hiroshi , Shimura Takuya , Sawa Takao , Amitani Yasutaka , Nakamura Toshiaki
Published: October 2002

In recent years, there has been a growing demand for acoustic communication
equipment for collecting data from observation devices installed underwater and
controlling remotely operated vehicles. With the objective of collecting data from
these devices, we developed a packet transmission system based on frequency shift
keying (FSK) modulation. This equipment is a half-duplex acoustic communication
device with a frequency of 20 kHz±1.25 kHz, transmission rate of
1,250 bps and a maximum acoustic power of 20 W. Using this equipment, a trial
was carried out in the sea at the depth of 3,500 m in October 1998. At a transmission
distance of approximately 4,000 m, it successfully transmitted error-free 15-kbytes
data.
Analysis of Sea Surface Reflection Waves Using the Wigner Distribution Function
Authors: Ochi Hiroshi , Futa Kohji , Kikuchi Toshiaki
Published: October 2002

Recently, the importance of high-speed acoustic data transmission has grown.
We are conducting research with the aim of revealing various phenomena that affects
underwater sound propagation and of realizing high-speed underwater acoustic data
transmission. In this paper, we applied time-frequency analysis using the Wigner
distribution function (WDF) to the analysis of received signals, and investigated
techniques that analyze the effect of the sea surface. Using data from a sea trial of an
8 kHz burst signal, we applied time-frequency analysis to surface reflected waves and
found that there is a time-varying frequency shift that is thought to be due to sea
surface reflection of a 5 ms burst signal. Moreover, as the pulse width increased to
10 ms, this fluctuation disappeared. This time-varying fluctuation is thought to
observe the movement of sea surface wedges. We also indicate that the reflected wave
is thought to be a diffracted wave by surface wedges.
Simulation of Ultrasonic Displacement in Random Medium Using Ultrasonic Speckle Tracking
Authors: Tjundewo Lawu Tjundewo Lawu , Mitsuhiro Ueda Mitsuhiro Ueda
Published: October 2002

The quantitative evaluation of ultrasonic displacement in tissue under
externally applied forces is a necessary step in the field of ultrasonic
diagnostics. In this study, the speckle tracking method is used to
investigate motion artifact produced by a rotating tissue.
An analytic prediction of this motion artifact in relation to system
characteristics (i.e., beam width, pulse duration, frequency and phase
of the signal) is presented.
The tissue is modeled as a random array of numerous point scatterers,
and RF signals are computed based on the convolutions between the
transmission pulse and the impulse response of each scanning line.
The preliminary results show that the artifact resulting from the
speckle tracking method depends on the beam width.
The method is quite general and can be extended to study the effects
of other tissue motion, in particular, the deformation of tissue.
A Method to Separate the Transmitting Signal and the Receiving Signal in FM-Chirp Pulse Compression Systems
Authors: Hu Zhiqiang , Tagawa Norio , Moriya Tadashi
Published: October 2002

We have developed a method of separating the transmitting and
the receiving signals for FM-chirp pulse compression systems for use
in intraductal ultrasonography. The method enables us to remove the
unnecessary signals and to obtain a sufficient delay time. In this
paper the following results are described: 1) A method to separate
the transmitting signal and the receiving signal with a
long-time-duration was proposed using a flexible guided line. 2) A
guided line suited for intravascular ultrasonography was constructed
using the L(0, 3) mode of the Pocchammer-Chree wave propagating in a
tapered fused quartz rod. 3) A tentative result was obtained that a
transmitting signal of a long-time-duration could be compressed to
give a short pulse. 4) To use this guided line in intraductal
ultrasonography, a method to design an optimum signal is necessary.
Decrease in Deposition Rate and Improvement of Step Coverage by CF4 Addition to Plasma-Enhanced Chemical Vapor Deposition of Silicon Oxide Films
Authors: Lim Sang Woo , Shimogaki Yukihiro , Nakano Yoshiaki , Tada Kunio , Komiyama Hiroshi
Published: October 2002

The low dielectric constant of F-doped silicon dioxide film
makes it suitable for use as an intermetal film to improve the
performance of ultra-large scale integrated circuits (ULSIs). One of
the properties required by an intermetal film is good gap filling. It
is known that fluorine addition to silicon oxide decreases the film
deposition rate and improves the step coverage. In order to
investigate these phenomena, we study the reaction mechanism of
plasma-enhanced chemical vapor deposition (PECVD) silicon oxide film
and its change by fluorine addition. Using a two film-forming species
model, we explain the dependence of the deposition rate and the step
coverage on the residence time for a SiH4/N2O-based PECVD
system. The precursor produced by the dissociation of SiH4 has a
relatively high sticking probability (≈0.5), while an
intermediate species has a low (<10-4) sticking probability.
The concentration of each species for deposition is changed by the
residence time of the gas, thus the deposition rate and the step
coverage show dependence on the residence time. The deposition rate
of silicon oxide films is decreased and the step coverage is improved
by CF4 addition during SiH4/N2O-based PECVD. From the
estimation of the sticking probability, we suggest that the reason for
the improvement of the step coverage by fluorine addition is not the
etching effect by CF4 addition, but the decrease in sticking
probability of the precursor produced by the dissociation of
SiH4.
Effects of Film Quality of Hydrogenated Amorphous Silicon Grown by Thermal Chemical-Vapor-Depositon on Subsequent in-situ Hydrogenation Processes
Authors: Yamanaka Mitsuyuki , Sakata Isao , Sekigawa Toshihiro
Published: October 2002

In-situ hydrogenation which is performed in a thermal
chemical-vapor-deposition (CVD) chamber by interrupting film growth
and by introducing atomic hydrogen is known to be effective for
decreasing the defect density in thermal CVD hydrogenated amorphous silicon
(a-Si:H). In this study we have experimentally examined the validity
of a previous implicit assumption that the film properties after
in-situ hydrogenation process could be insensitive to the quality of starting CVD films. This assumption has been proved to be invalid
and it has been clarified that one must start with high quality CVD
samples in order to obtain high quality samples after in-situ
hydrogenation. We explain the present results by assuming that the
film structure of the thermal CVD a-Si:H, which affects the hydrogen
penetration into the lattice during hydrogen plasma treatment and
consequently the defect passivation, can vary with CVD growth
conditions.
Reactive Ion Etching of ZnSe, ZnSSe, ZnCdSe and ZnMgSSe by H2/Ar and CH4/H2/Ar
Authors: Chen W. R. , Chang S. J. , Su Y. K. , Lan W. H. , Lin A. C. H. , Chang H.
Published: October 2002

The etching characteristics of ZnSe, ZnS0.07Se0.93, Zn0.88Cd0.12Se and Zn0.95Mg0.05S0.09Se0.91have been studied using 2CH4/9H2/2Ar and 9H2/2Ar as the reactive ion etching (RIE) etching gas. It was demonstrated that a smooth surface and a good anisotropic feature can be achieved when these samples are etched in 9H2/2Ar at 60 mTorr with a 150 W plasma power. Under this etching condition, the etching rates of ZnSe, ZnS0.07Se0.93, Zn0.88Cd0.12Se and Zn0.95Mg0.05S0.09Se0.91were 7.8 nm/min, 9.5 nm/min, 10.4 nm/min and 8.3 nm/min, respectively. Carbon-related needlelike features were observed when methane was added to the etching gas, and these needlelike features can be removed by a high plasma power. Photoluminescence (PL) measurement shows that 9H2/2Ar can induce a greater amount of surface damage than 2CH4/9H2/2Ar. However, these damages can be partially removed by post etching annealing. The optimal annealing temperature is 450°C for samples etched in 9H2/2Ar and 250°C for samples etched in 2CH4/9H2/2Ar.
Robust Operation of a Novel Frequency Divider Using Resonant Tunneling Chaos Circuit
Authors: Yoichi Kawano Yoichi Kawano , Shigeru Kishimoto Shigeru Kishimoto , Koichi Maezawa Koichi Maezawa , Takashi Mizutani Takashi Mizutani
Published: October 2002

We studied operating margins of the novel frequency divider using the resonant tunneling chaos circuit with respect to input signal distortions and the variations in the current-voltage characteristics of the resonant tunneling diodes (RTDs). It was shown by numerical simulation that the input signal distortions caused by harmonics which make the input signal approach the square wave and triangular wave have only a small effect on the frequency divider operation. This was confirmed using a test circuit consisting of discrete devices. Finally, it was also demonstrated by circuit simulation that this frequency divider can operate properly against the fluctuations in epitaxial growth and fabrication process conditions causing the changes of the peak to valley (p/v) current ratio and the peak current density of the RTD.
Miniaturized Blue Laser using Second Harmonic Generation
Authors: Kitaoka Yasuo , Yokoyama Toshifumi , Mizuuchi Kiminori , Yamamoto Kazuhisa
Published: October 2002

We demonstrate a miniaturized blue laser (5×12×1.5 mm3) using second harmonic generation (SHG), which
consists of a quasi-phase-matched (QPM)-SHG waveguide device on an
x-cut Mg-doped LiNbO3 substrate and a tunable
distributed-Bragg-reflector (DBR) laser diode. By using the QPM-SHG
waveguide device on an x-cut substrate, efficient optical coupling
was realized without a half-wave plate, and the maximum coupling
efficiency of 75% was achieved. The blue light power of 2 mW was
generated for the fundamental coupling power of 20 mW, which agreed with a
conversion efficiency of 10%. The mechanical stability of the
planar-type butt-coupled SHG blue laser was examined, where the
coupling efficiency was maintained constantly under the change of
module temperature and the temperature cycle test from 10 to
60°C. We succeeded in downsizing the SHG blue laser to
0.1 cm3, which is sufficiently small for its application to
optical disk systems.
Effect of Pore Size Distribution on Humidity Sensing Properties of MgO doped ZrO2–TiO2 Ceramic
Authors: Jain M. K. , Bhatnagar M. C. , Sharma G. L.
Published: October 2002

The MgO doped ZrO2–TiO2 composite is studied for its
humidity sensing characteristics. Though dc electrical properties show
very high sensitivity to humidity, it is not useful for practical
applications because of the charging effect. The ac conductivity vs
relative humidity characteristics of the pellet becomes linear with an
increase in sintering temperature. The post treatment at high
temperature and high humidity is found to accelerate initial ageing of
the pellet and therefore, stabilizes the characteristics more
quickly. A physical model has been proposed to correlate initial
ageing, effect of sintering temperature and response time with pore
size distribution. Pores below 300 Å radii are present in
abundance near the ZrTiO4 phase formation temperature. These
pores are responsible for higher sensitivity in low humidity region
and linear characteristics.
Analysis of Read-out Signals in Land/Groove Recording of a Phase-Change Optical Disc
Authors: Chung Moonkyo , Chung Kyung Min , Lee Taek Sung , Cheong Byung-ki , Kim Won Mok , Song Ki-Bong , Kim Young Dong , Kim Soon Gwang
Published: October 2002

We have analyzed the read-out signal obtained from a phase-change optical disc. The marks were recorded both on land tracks and in groove tracks with the focused laser beam of a wavelength of 685nm and a numerical aperture (NA) of 0.6. Characteristics of the read-out signal of marks recorded both on land tracks and in groove tracks were understood by considering the land/groove configuration of the substrate, the reflectance difference and the phase difference between amorphous and crystalline states of a recording layer. By comparing the measured carrier levels obtained from the land and groove tracks with the simulation results based on the diffraction theory, we found that the measured carrier level difference between land and groove recordings resulted mainly from the effects of groove geometry and the phase difference which was estimated to be 20° for our sample disc. For this work, the groove geometry of the substrate and mark sizes were precisely estimated from transmission electron microscopy (TEM) micrographs.
Computer-Aided Design and Analysis of Rewritable Phase-Change Optical Disk
Authors: Liu Rong Zhao , BaoXi Xu BaoXi Xu , Luping Shi Luping Shi
Published: October 2002

The dependence of the optical and thermal characteristics of phase-change optical disks on the multilayer disk structure was analyzed and simulated. Using the integrated software developed, a phase-change optical disk structure for a blue laser is designed with both optical and thermal considerations, and a suitable disk structure is proposed. Based on the designed disk structure, writing and rewriting processes are simulated, and the results are satisfactory.
Fourth-Order Piezoresistance Coefficients in Cubic Semiconductors
Authors: Ohmura Yamichi , Morinaga Wataru
Published: October 2002

It has been shown, by tensor property and crystallographic
symmetry considerations, that there are 70 independent nonzero
components in the fourth-order piezoresistance coefficients in cubic
conductors. For cubic semiconductors such as Si and Ge or GaAs,
which crystallize in diamond (Oh) or zincblende
(Td) structures, respectively, these 70 nonzero
components reduce to 42 components. The fourth-order piezoresistance
coefficients for several current and stress directions have been
shown in terms of these 42 components. Relevant quantities such as
the pressure coefficients of resistivity are discussed.
Kinetics of the Ferroelectric-Paraelectric Transition of Copolymers of Vinylidene Fluoride with Trifluoroethylene Studied by Time Evolution of Dielectric Permittivity
Authors: Yoshiyuki Takahashi Yoshiyuki Takahashi , Takeo Furukawa Takeo Furukawa
Published: October 2002

The time evolution of the dielectric permittivity was measured for copolymers of vinylidene fluoride (VDF) with trifluoroethylene (TrFE) during the ferroelectric-paraelectric transition induced by a temperature jump. The results were analyzed on the basis of a nucleation-growth model. The characteristic time constant associated with transition kinetics was shown to depend on the degree of supercooling or superheating. The evaluated equilibrium transition temperature was located between the apparent transition temperatures during heating and cooling at a constant rate. The surface free energy between the two phases considerably decreased with increasing TrFE content in accordance with a change in transition type from the first order to second-order-like.
Numerical Simulations of Films Formed by Cluster/Particle Co-Deposition in Atmospheric-Pressure Chemical Vapor Deposition Process Using Organic Silicon Vapors and Ozone Gas
Authors: Adachi Motoaki , Fujimoto Toshiyuki , Itoh Yoshifumi , Okuyama Kikuo
Published: October 2002

In order to confirm the previously developed numerical simulation for film formation by cluster/particle co-deposition in the atmospheric-pressure chemical vapor deposition [Fujimoto et al..: J. Appl. Phys. 85 (1999) 4196], simulation results were compared with experimentally obtained growth rates and surface morphologies of films prepared from four organic silicon vapors [tetraethylorthosilicate (TEOS), triethoxysilane (TRIES), tetramethylorthosilicate (TMOS), and octamethylcyclotetrasiloxane (OMCTS)] and ozone gas using a flow-type vertical tube reactor. For TEOS, TRIES and TMOS, the simulation results could explain reasonably experimentally determined film growth rate, particle deposition rate and surface morphology of film when natural convection did not occur in the reactor. However, the numerical simulation could not estimate film formation from OMCTS.
Observation of Surface Blistering by Grazing Incidence Electron Microscopy
Authors: Muto Shunsuke , Matsui Tsuyoshi , Tanabe Tetsuo
Published: October 2002

We demonstrate grazing incidence electron microscopy (GIEM) for
observation of surface blistering introduced by energetic particle
bombardment. This method enebles us direct and nondestructive
observation and characterization of surface protrusions without any
modification of the microscope, when it is used in combination with
associated analytical instruments. As an example, the surface
blistering of D+-irradiated single crystalline silicon was
examined with the aid of the simultaneous application of electron
energy-loss spectroscopy (EELS).