bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Microstructure on the Ultrasonic Backscattered Energy from a Liquid/Solid Interface at the Rayleigh Angle
Authors: Kim Ho Chul , Lee Jeong Ki , Kim Sang Young , Kwon Sung Duk
Published: October 2002

The scattered ultrasonic energy from a liquid/solid interface at the Rayleigh
angle, E
s, was theoretically derived by considering the interaction
between the energy of the penetrated Rayleigh wave, E
0, and the
microstructure in the subsurface within the Schoch displacement,
Δs, as E
s = 0.25 αs Δs
E
0, where αs is
the attenuation coefficient due to scattering.
The backscattered ultrasonic energy, E
Bs, at the Rayleigh angle was also
derived as E
Bs ∝D
3
f
3 in the Rayleigh scattering region and
E
Bs ∝D
f in the stochastic scattering region, where D is the
average grain size and f is the frequency.
The grain size and the frequency dependence of the backscattered ultrasonic
energy at the Rayleigh angle were obtained by both integration and power
spectrum analysis of the backscattered signals from the interface between the
water/stainless steel plates with the average grain size varying between 5.6
and 40.5 µm.
The exponents of the grain size and the frequency dependence obtained by both
methods were about 3.5 and 2 in the region of λR ≥6 πD and
λR ≤6 πD, respectively.
The deviation of the exponents is attributed to the direct scattering from the
surface irregularities in the region of λR ≥6 πD and the
stochastic scattering due to grain size distribution in the region of
λR ≤6 πD.
This implies that the exponents depend on the ratio of the average size of the
scatterer to the wavelength of the Rayleigh wave.
The results suggested that the backscattered ultrasonic wave at the Rayleigh
angle was built up predominantly by the scattering from the grain boundaries in
the subsurface within the Schoch displacement and the direct scattering from
the irregularities on the surface.
Growth Condition Dependence of the Photoluminescence Properties of InxGa1-xN/InyGa1-yN Multiple Quantum Wells Grown by MOCVD
Authors: Harris Janet C. , Brisset Helene , Someya Takao , Arakawa Yasuhiko
Published: October 2002

In
x
Ga1-x
N/In
y
Ga1-y
N multiple quantum wells have been grown by atmospheric pressure
metalorganic chemical vapour deposition and characterised by photoluminescence (PL)
measurements. The influence of many different growth parameters has been systematically
investigated. Use of a high ammonia flow rate and a moderate hydrogen flow rate are observed to be
very important for obtaining samples of high indium content and high PL intensity. A low total gas
flow rate is also found to be best, and the benefits of using low growth rate and high trimethylindium
flow rate are confirmed. Room temperature PL linewidths as low as 64 meV have been achieved.
Electrical Properties of Al/(BaXCa1-X)F2/i-Diamond Metal-Insulator-Semiconductor Structures
Authors: Yun Young , Tanaka Hiroyuki , Itoh Akihiro , Maki Tetsuro , Kobayashi Takeshi
Published: October 2002

Various Al/(Ba
X
Ca1-X
)F2/i-diamond
metal-insulator-semiconductor (MIS) structures were prepared, and
their electrical properties were closely investigated for the first
time. The C-V characteristics and surface state density
distributions revealed that the surface state density of the MIS
interface decreases as the ratio of the Ba constituent in an
insulator increases, which reconfirms our previous view about the
role of Ba atoms in an insulator: adsorbed oxygen on the diamond
surface was eliminated via strong chemical reaction of constituent
Ba atoms with oxygen during film deposition, and electrical
stabilization of the diamond surface was obtained by reduction of
the adsorbed oxygen. In the case of
Al/(Ba0.7Ca0.3)F2/i-diamond MIS structure, a low
surface state density (from ∼1010 to
∼1011/(cm2·eV)) was observed in the vicinity of
the valence band edge, and an efficient electrical modulation of the
surface band was obtained. This result indicates that
(Ba
X
Ca1-X
)F2/i-diamond structure is a promising
candidate for application to diamond MIS devices.
0.10 µm Dense Hole Pattern Formation by Double Exposure Utilizing Alternating Phase Shift Mask Using KrF Excimer Laser as Exposure Light
Authors: Nakao Shuji , Nakae Akihiro , Tsujita AtsumiYamaguchi , Wakamiya Wataru
Published: October 2002

Dense 0.10 µm hole pattern formation is achieved by
optical lithography with a KrF excimer laser. A Double
exposure utilizing two alternating phase shift masks (PSMs)
of the line-and-space (L/S) pattern laid out in different
directions produces a dense and small hole image in bright
field with large focus and exposure latitude. Applying this
method with a KrF excimer laser stepper and a chemically
amplified negative-tone resist, a two-dimensional (2-D) 0.10 µm
hole array with 0.40 µm pitch is resolved with a 0.6 µm
depth of focus (DOF). The hole diameter and pitch in the
resolution limit seem to be less than 0.10 µm and 0.28 µm,
respectively. Also, 2-D hole arrays with different pitches
in the x and y directions are easily formed using masks with
different pitches in each direction. The hole pattern of an
actual DRAM cell is successfully formed by this method.
Because of the excellent patterning performance, this method
will enable the fabrication of multi giga bit DRAMs by KrF
excimer laser lithography.
Coherent Dynamics of Excitons in an Island-Inserted GaAs/AlAs Quantum Well Structure: Suppression of Phase Relaxation and a Deep Quantum Beat
Authors: Toshio Matsusue Toshio Matsusue , Hidefumi Akiyama Hidefumi Akiyama , Toshiharu Saiki Toshiharu Saiki , Chari Ramkumar Chari Ramkumar , Masayuki Shirane Masayuki Shirane , Ryo Shimano Ryo Shimano , Makoto Kuwata-Gonokami Makoto Kuwata-Gonokami , Hiroyuki Sakaki Hiroyuki Sakaki
Published: October 2002

The degenerate four-wave mixing technique in the self-diffraction geometry is employed to investigate a novel GaAs/AlAs quantum well microstructure. Time-integrated transient measurements are carried out to study the coherent dynamics of excitons in a GaAs quantum well with AlAs islands inserted at the center of the well (IIQW) in excitation densities from 6×109 to 1.5×1011 cm-2.
The decay of the time-integrated self-diffracted signal shows slower dephasing for the IIQW compared to that of a normal quantum well (NQW) without island insertion. The dephasing rate is found to increase slightly in the IIQW, while it is found to increase sharply in the NQW with the excitation density. A deep beat with a period of 1.45 ps, which disappears for co-circular polarization configuration, is observed in the decay of the self-diffracted signal in the IIQW. The detection-energy-resolved measurement reveals that the modulation of the beat increases up to full depth at low detection energy with respect to the peak energy of the self-diffracted signal. The dependence on detection energy and on polarization configuration shows that the beat is a quantum beat due to biexcitonic effect, which is enhanced by localization due to island insertion.
Luminescence of Mixed-Mode Exciton-Polariton in CuGaS2
Authors: Masami Susaki Masami Susaki , Kazuki Wakita Kazuki Wakita , Nobuyuki Yamamoto Nobuyuki Yamamoto
Published: October 2002

The luminescence spectra of the mixed-mode exciton-polariton
in CuGaS2 are studied at 8.6 K in conjunction with the
absorption spectra.
By measuring emitted photons as a function of propagation direction with
respect to the z axis of the crystal, it is possible to vary the magnitude
of a longitudinal-exciton and extraordinary-photon coupling.
The effects of this coupling on the resonance energy and oscillator strength
of the extraordinary exciton-polariton are established for the emission line
of the Γ4 free exciton which exhibits a doublet structure.
In contrast, the emission spectra due to the ordinary photons show one
weak, sharp line in the same intrinsic exciton region as
the Γ4 line.
The polarization dependence of the emission intensity is greatly reduced
for this sharp line. The behavior is interpreted as arising due to
the optically forbidden exciton having Γ3 symmetry.
The resonant exciton transitions to the lower exciton-polariton branch
and the forbidden state are observed in the extraordinary and
ordinary absorption spectra, respectively.
Control of Single-Electron Device Using Environmental Impedance Modulation
Authors: Fujio Wakaya Fujio Wakaya , Fumiyoshi Yoshioka Fumiyoshi Yoshioka , Hitoshi Higurashi Hitoshi Higurashi , Shuichi Iwabuchi Shuichi Iwabuchi , Yosuke Nagaoka Yosuke Nagaoka , Kenji Gamo Kenji Gamo
Published: October 2002

A single-electron-tunneling (SET) device with variable environmental
impedance is investigated.
A self-consistent numerical calculation shows
that the resistive environmental impedance
can control the SET device.
It is experimentally observed that the Coulomb gap becomes wider
as the resistive environmental impedance becomes larger as predicted by
the calculation.
From discussion of the shape of the Coulomb diamond,
it is concluded that
the observed enlargement of the Coulomb gap is due to the
electromagnetic environment effect of the Coulomb blockade.
Microstructure of Cu(In,Ga)Se2 Films Deposited in Low Se Vapor Pressure
Authors: Shiro Nishiwaki Shiro Nishiwaki , Naoki Kohara Naoki Kohara , Takayuki Negami Takayuki Negami , Hideo Miyake Hideo Miyake , Takahiro Wada Takahiro Wada
Published: October 2002

The microstructure of Cu(In,Ga)Se2 (CIGS) films deposited under low Se flux was studied using scanning electron microscopy, scanning Auger electron spectroscopy and high resolution and analytical electron microscopy.
CIGS films were deposited on Mo coated soda-lime glass substrate using the “3-stage” process in which the Se flux used during the third stage was restricted to a forth of standard value.
In the as-grown CIGS films, voids were observed along the grain boundaries and a Cu2Se phase was identified at the surface and the grain boundaries.
The voids and Cu2Se layer were produced by vaporization of an In–Se compound from the films during the third stage of deposition.
A reaction model on the CIGS grain surface is proposed based on the microstructure observations.
Dynamic Photocurrent Images of a Gas Sensing Surface
Authors: Vasconcelos Elder Alpes de , Uchida Hidekazu , Zhang Wenyi , Katsube Teruaki
Published: October 2002

A high-speed surface photovoltage technique which uses a
numerically processed parallel lock-in amplifier was applied to obtain
olfactory images. This high-speed system has measurement time short
enough to allow the observation of the time evolution of gas response
patterns. Representative images are presented and some of their
characteristic features, such as the influence of gas type and the
direction of gas flow, are discussed. Possible directions for further
improvement of the system are also discussed. The capability to obtain
dynamic photocurrent images is an important step towards real-time
visualization and further development of olfactory camera technology.
Static Contact Angle of Sessile Air Bubbles on Polymer Gel Surfaces in Water
Authors: Suzuki Atsushi , Kobiki Yasuhiro
Published: October 2002

We have measured the static contact angle of sessile air bubbles in water on poly (N-isopropylacrylamide) (NIPA) gel surfaces. The temperature dependence of the contact angle was measured on two different kinds of samples, consisting of homogeneous networks (transparent) and of phase-separated networks (opaque). It was found that the transparent gel exhibits a sharp but continuous decrement in the contact angle upon heating in the vicinity of the transition point, while the opaque gel does not show any appreciable change. The absolute value of the contact angle of the transparent gel in the collapsed state is evidently smaller than that of the opaque gel.
These results were qualitatively discussed in terms of not only the chemical but also the physical
surface properties in response to the temperature change; the former is the balance of the
hydrophobic-hydrophilic interactions in this system, and the latter includes the surface polymer
density, the surface roughness, and the network inhomogeneity.
Tin Oxide Films Deposited by Ozone-Assisted Thermal Chemical Vapor Deposition
Authors: Jeong-Woon Bae Jeong-Woon Bae , Sang-Woon Lee Sang-Woon Lee , Kook-Hyun Song Kook-Hyun Song , Jung-Il Park Jung-Il Park , Kwang-Ja Park Kwang-Ja Park , Young-Wook Ko Young-Wook Ko , Geun-Young Yeom Geun-Young Yeom
Published: October 2002

Transparent conductive tin oxide (TO, SnO2) films have been prepared by low pressure metal organic chemical
vapor deposition (LP-MOCVD) from various mixtures of tetramethyltin (TMT) with oxygen and oxygen containing
2.96 to 5.1 mol% O3. The properties of TO films have been changed with the gas flow rate (oxygen, oxygen
containing ozone) and the substrate temperature. The use of oxygen containing ozone instead of pure oxygen reduced
substrate temperature significantly and the resistivity while maintaining the same growth rate. The films prepared
using ozone showed resistivity ranging from 10-2 to 10-3 Ωcm, and ranging mobility from 10.5 to 13.7 cm2/Vs.
Calibration of the Lidar Measurement of Tropospheric Aerosol Extinction Coefficients
Authors: Kinjo Hideki , Kuze Hiroaki , Sakurada Yasushi , Takeuchi Nobuo
Published: October 2002

In the derivation of the vertical profile of tropospheric aerosols from lidar
data, one has to assume an appropriate value for the aerosol extinction
coefficient at a reference point, a few kilometers or more above the ground. If
the aerosol contribution at this point is not negligible compared to the
molecular contribution, the resulting aerosol extinction through the
atmosphere is affected by this boundary value. Here we propose the use of a
ground-level extinction coefficient measured by an integrating nephelometer
for the calibration of lidar data. In order to connect the ground value to the
overlap point of a vertical lidar, additional data are provided from slant path
observation using a portable lidar.
Radiation Losses of Cylindrical SF6 Gas Arc
Authors: Palov Alexandre , Horinouchi Katsuhiko
Published: October 2002

The net emission coefficient is calculated for the SF6 plasma arc in local thermodynamic
equilibrium. Both continuum and line radiation are taken into account. A thermal Doppler, natural and
collision broadening are considered in order to describe bound-bound transitions.
The net emission coefficients calculated are given for the isothermal cylindrical arc of 0.2–3 cm
radius, 1017–1019 cm-3 ionic concentration and 10,000–40,000 K temperature. The results obtained show
significant differences from the numerical calculations of other authors, especially for temperatures greater
than 25,000 K.
High-Speed Detection of Ballistic Photons Propagating through Suspensions Using Spectral Interferometry
Authors: Takahisa Mitsui Takahisa Mitsui
Published: October 2002

I describe spectral interferometry (SI) with incoherent radiation to detect ballistic photons propagating through suspensions. SI detects mutual interference between a sampling beam and a reference beam, even in cases where the former is not equal to the latter in regard to propagation delay time. I have succeeded in eliminating virtual images by performing three spectral measurements with three different reference beam phases. By removing virtual images, the observed dynamic range is increased by 20 db. SI has potential for improving the image-obtaining time of optical computed tomography. In my experiment, a one-line scan time of 200 µs has been achieved.
Comparative Experiments of Protein Denaturation for Studying Structural Difference of Homologous Membrane Proteins: P-450scc and P-45011β
Authors: Suzuki-Tomii Keiko , Ohta Yoshihiro , Kawato Suguru , Mitaku Shigeki
Published: October 2002

The topological difference between two homologous membrane proteins,
cytochromes P-450scc and P-45011 β in the inner membrane of bovine adrenocortical
mitochondria, was studied by denaturation experiments, using urea and 1-pentanol as
denaturants. Both P-450s denatured at the urea concentration of about 2.5 M that is
in the concentration range of the denaturation of soluble proteins. In contrast, P-45011 β was denatured by 1-pentanol, which is an efficient denaturant of membrane
proteins, at a much lower concentration than P-450scc. These results suggested that
the membrane domain is more strongly coupled with the soluble functional domain in
P-45011 β than P-450scc. It was also indicated that the comparative experiments of
protein denaturation by urea and alcohol provide a simple method to identify the
structural difference of homologous membrane proteins.
N2
+ Implantation Approaches for Improving Thermal Stability of Cu/Mo/Si Contact Structure
Authors: Tae Kim Yong , Joon Kim Dong , Jong-Wan Park Jong-Wan Park
Published: October 2002

We have suggested N2
+ ion modification method to improve the thermal stability of Mo thin film by implanting 3 ×1017 N2
+ ions/cm2 with very low acceleration energy of 20 keV. The Mo film modified by N2
+ ions (Mo–N2
+) keeps microcrystalline after annealing at 600°C and performs excellent diffusion barrier against Cu atoms at 700°C for 30 min. The stress evolution of the Mo–N2
+ thin film during the annealing process indicates that highly compressive stress changes to low tensile stress at 600 °C for 30 min.
Ultrasonic Sensors for High Temperature Applications
Authors: Tittmann Bernhard R. , Aslan Mustafa
Published: October 2002

Many processes take place under conditions other than ambient, and chief among these is high temperature. Examples of high temperature industrial processes are resin transfer molding, molten metal infiltration and rheocasting of composite metals alloys. The interaction of waves with viscous fluids is an additional complication adding to an already complicated problem of operating a sensor at high temperature for extended periods of time. This report attempts to provide an insight into the current state of the art of sensor techniques for in-situ high temperature monitoring.
Application of Ultrasound Energy as a New Drug Delivery System
Authors: Tachibana Katsuro , Tachibana Shunro
Published: October 2002

Ultrasound has been in use for the last three decades as a
modality for diagnostic imaging in medicine. Recently, there have been
numerous reports on the application of nonthermal ultrasound energy
for targeting or controlling drug release. This new concept of
therapeutic ultrasound combined with drugs has led to much excitement
in various medical fields. Ultrasound energy can enhance the effects
of thrombolytic agents such as urokinase. Therapeutic ultrasound
catheters are currently being developed for treatment of
cardiovascular diseases. Devices with ultrasound transducers implanted
in transdermal drug patches are also being evaluated for possible
delivery of insulin through the skin. Chemical activation of drugs by
ultrasound energy for treatment of cancers is another new field
recently termed “Sonodynamic Therapy”. Various examples of ultrasound
application are under investigation which could lead to revolutionary
drug delivery systems in the future.
Computer Experiments on Surface Excitations in Three-Dimensional Model Crystals
Authors: Hiki Yosio , Komuro Ryouichi , Minato Atsushi , Ozawa Satoru
Published: October 2002

Molecular dynamics computer simulations were carried out for three-dimensional anharmonic mass-spring model crystals. Between the nearest
and next nearest neighbor atoms central forces were considered, and
anharmonic potential up to the fourth order was taken into account. An
input pulse displacement was given to atomic rows on a free surface of
the crystal, and the induced displacements on the surface and in the
bulk of the crystal were computed. Solitons were produced as atomic
excitations when only the nearest neighbor atomic interactions were
considered. Simulations were carried out under various computational
conditions to determine the characteristics of soliton production.
Velocity Curve Change of Leaky Lamb Waves in a Layered Substrate Induced by Liquid-Loading
Authors: Motegi Kenji , Toda Kohji
Published: October 2002

A liquid-loading effect on the propagation characteristics of leaky Lamb waves (LLWs) is studied, based on numerical calculations and experiments. A layered substrate consisting of a thin piezoelectric ceramic plate and a
thin acrylic plate is used as a propagation guide of the LLW. Interdigital
transducers are mounted on the free surface of the ceramic plate and a liquid
is in contact with one of the two surfaces of the acrylic plate. Under the
condition that the density ratio of water and the acrylic plate is high (0.85), anomalous behaviors of the velocity dispersion curves appear, which do not occur for water-loading on substrates with much higher densities such as ceramic and glass plates. Two typical features of the LLW propagating in the
layered substrate are jump of the propagation mode under the influence of the liquid-loading and the modal change of the interaction between two propagation
modes. The state change of mode coupling induced by liquid loading is promising for constructing sensing devices.
Analysis of Scattering Energy Flow by Near-Field Acoustic Holography
Authors: Kenji Saijyou Kenji Saijyou , Mamoru Egawa Mamoru Egawa , Shigeru Yoshikawa Shigeru Yoshikawa
Published: October 2002

Acoustic scattering from a submerged cylindrical shell is experimentally investigated from the viewpoint of energy flow.
Acoustic and structural intensities, which respectively indicate acoustic and vibrational energy flows, are obtained by processing data from near-field acoustical holography.
Both acoustic and structural intensities of the scattering wave are treated by using a radiation propagator.
An incident wave propagator is also introduced to measure both acoustic and structural intensities of the incident wave from an external source.
The interrelationship between structural and acoustic energy flows of the present scattering problem is examined by comparing experimental and simulated results.
Brillouin Scattering in Densified GeO2 Glasses
Authors: Ishihara Tohru , Shirakawa Yoshiyuki , Iida Takamichi , Kitamura Naoyuki , Matsukawa Mami , Ohtori Norikazu , Umesaki Norimasa
Published: October 2002

Brillouin and Raman scattering measurements have been applied
for the investigation of GeO2 glasses densified under high pressures up to 9 GPa at 673 K. The density of obtained glasses increases with an
increase of applied pressure. It increases significantly around 3 GPa,
however, shows a peak at 6 GPa. A significant increase is also observed in
hypersonic wave velocity, and longitudinal and shear moduli around 3 GPa. These results are well explained by amorphous-amorphous
transition. In Raman scattering measurement, vibrational modes illustrate
continuous changes of local structures with increasing applied pressures
up to 9 GPa. Boson peaks show a maximum around 3 GPa, which
indicates the minimum correlation length. These data suggest a change
in the intermediate-range structure.
Acoustooptic Effects of Nematic Liquid Crystals Induced by Elastic Wave Propagating in Glass Substrate
Authors: Hiroshi Moritake Hiroshi Moritake , Tadaaki Seike Tadaaki Seike , Kohji Toda Kohji Toda
Published: October 2002

An elastic wave delay line with a glass plate as a propagation
medium is investigated in relations to acoustooptic effects of nematic
liquid crystals. A nematic liquid crystal cell is mounted on the central
region of a glass plate for elastic wave propagation. The elastic wave
propagating in the glass plate interacts with the liquid crystal in a wide
frequency range. Two types of periodical domain structures are observed
in the nematic liquid crystal cell under the existence of the elastic
wave. One exists in both homeotropically and homogeneously aligned
cells, and depends not on the kind of liquid crystal but on the carrier
frequency of the elastic wave. The other is recognized only in
homogeneously aligned cells and depends on the layer thickness and the
kind of liquid crystal, but not on the carrier frequency of the elastic
wave. Both periodical domain structures are induced by the elastic wave
propagating in the glass plate.
Detection of a Transition Layer near the External Surface of Thermally-Grown Silicon Oxides
Authors: Watanabe Yoshio
Published: October 2002

This study was undertaken to detect the oxide transition layer near the
external surface of a silicon oxide layer thermally grown at 800–1000°C in dry
O2. A difference between the O content of the oxide near the external surface
and of the bulk oxide is found using an improved depth profiling method,
namely, Auger electron spectroscopy in conjunction with ion sputtering. We
also found a difference in chemical etching rate between the oxide near the
surface and that of the bulk oxide. From our result, we confirm that a 1–2-nm-thick transition layer that is high in O content and has a high chemical etching
rate, exists at the surface of the oxide layer. The surface transition layer is
inferred to be composed of an incomplete SiO2 network containing an appreciable number of end groups or peroxides.
Lateral Ambiguity Analysis of Complex One-Bit Correlational Method for Two-Dimensional Speckle-Echo Tracking
Authors: Tomoyuki Yagi Tomoyuki Yagi , Sin-ichi Yagi Sin-ichi Yagi
Published: October 2002

We have previously reported that highly accurate displacement estimation in the lateral direction is
possible using the complex one-bit correlational method, and that the first practical
application of dynamic distortion diagnosis has been realized. In this paper,
in order to clarify displacement estimation performance of the complex one-bit
correlational method, we report that the stepwise displacement response characteristics in
the lateral direction were estimated using measured displacement data. Furthermore,
the relationship between the point spread function (PSF) of the measurement system
and the estimation capacity was obtained by computer simulation.
Ultrasonic Underground Imaging Using Amplitude Correlation Synthesizing Method
Authors: Tao Liang , Tanaka Takashi , Motooka TsutomuWatanabe , Murayama Shigeki , Ihara Yoshihisa
Published: October 2002

An amplitude correlation synthesis processing (ACSP) method is proposed for ultrasonic
underground imaging, in order to reduce the error image reconstructed with the low-frequency
signal received by linear array receivers. In contrast to the previous method of special polarity
correlation processing (SPCP), the amplitudes of received signals corresponding to a
processing point, in every subarray group, is multiplied according to polarity condition, and all
the conditional multiplication outputs are synthesized, in the ACSP method. For the
experiment, an electromagnetic induction type sound source is employed as a powerful impulse
incident ultrasound. A comparison of the imaging results of bodies buried 1 m underground,
derived both by the ACSP and SPCP methods shows that the new method eliminates most of
the error images, and hence its efficiency for imaging with a low signal-to-noise ratio (SNR)
signal is verified.
Photoacoustic and Photocurrent Studies of Highly Porous TiO2 Electrodes Sensitized by Quantum-Sized CdS
Authors: Toyoda Taro , Saikusa Koji , Shen Qing
Published: October 2002

Photoacoustic (PA) and photocurrent (PC) spectra of highly porous TiO2 have
been measured. The PA spectrum shifts to the lower energy region and the PA intensity
below the fundamental absorption edge of TiO2 increases rapidly with an increase in
the number of CdS coating layers to seven and becomes almost constant at more than
seven layers. The increase in PC intensity and a clear shift of spectra to the lower
energy region are observed with increasing number of CdS layers coated, indicating
the possibility of the transfer of photoexcited electrons of CdS nanocrystals to the
conduction band of TiO2.
Improved Method for Three-Dimensional Imaging in Photoacoustic Microscope
Authors: Minamide Akiyuki , Shida Sumiaki , Tokunaga Yoshiaki
Published: October 2002

The proposed new method partially solves the problem of low signal-to-noise-ratio (SNR)
when modulation frequency increases. In this paper, we suggest to keep constant the amplitude
of the detected photoacoustic (PA) signal by linearly increasing the modulation voltage versus
frequency. The PA signal of the sample can be easily estimated by fast Fourier transform. It is
also demonstrated that the presented method is able to detect a subsurface flaw in a graphite in
the 10–100 Hz frequency range.
Probing the Discrete Level Spectrum of Open Quantum Dots
Authors: Bird Jonathan P. , Ferry RichardAkis , Aoyagi JohnCooper , TakuoSugano TakuoSugano
Published: October 2002

Low temperature measurements of open quantum dots exhibit a series of periodic oscillations in their conductance as a function of gate voltage at zero magnetic field. Realistic numerical simulations of the devices confirm the basic observations of experiment and reveal the existence of periodically recurring wavefunction scars. The simple periodicity of the conductance oscillations and the strong scarring of the wavefunction in the dot suggest that theintrinsictransport properties of these devices are dominated by the selective excitation of a small number of dot states, even in the absence of an applied magnetic field.
Reaction on Electromechanical Characteristics due to Acoustic Radiation from Substrate with Energy Confinement and Interference in Interdigital Transducer
Authors: Michio Ohki Michio Ohki , Kohji Toda Kohji Toda
Published: October 2002

In a piezoelectric substrate
on which two interdigital transducers (IDTs) are located,
the electromechanical characteristics of the IDT(s),
the admittance of the 1st IDT
and the transmission from the 1st IDT to the 2nd IDT,
are measured in the following two cases:
when the substrate is in contact with a load medium
and the radiation of the energy
from the substrate into the load medium occurs,
and when the substrate is in contact only with air
and the radiation does not occur.
Measurements show
that the electromechanical characteristics
have a certain periodicity in the frequency domain
only when the radiation occurs,
which is explained by the reaction of the radiation.
Since the radiation intensity from the substrate
has a periodicity in the frequency domain
due to the energy confinement
and the interference inside the IDT,
the electric current in the IDT is reduced
and also becomes periodic.
Parameters in the Coupling-of-Modes Equations for a Natural Single-Phase Unidirectional Transducer and a Transduction Center Shift Reversal of Directivity Transducer on a La3Ga5SiO14 Substrate
Authors: Inagawa Kiyoshi , Hasegawa Koji , Koshiba andMasanori
Published: October 2002

Parameters included in coupling-of-modes equations such as coupling coefficient,
transduction coefficient and electrode capacitance are theoretically determined using
the finite-element method (FEM) for a natural single-phase unidirectional transducer
(NSPUDT) and a transduction center shift reversal of directivity transducer (TCS-RDT) on La3Ga5SiO14 piezoelectric single crystal which has a higher
electromechanical coupling coefficient compared to quartz. The electrode thickness
dependence of the parameters and the excitation characteristics of NSPUDT and TCS-RDT are investigated in detail. For NSPUDT, the parameters obtained by the present
method are compared with those obtained by the perturbation method. Furthermore,
numerical results for the frequency characteristics of NSPUDT are compared to the
experimental data, and the validity and usefulness of the present method are
demonstrated.
Surface Acoustic Wave Properties of La3Ga5SiO14 (LANGASITE) Single Crystals
Authors: Masatoshi Adachi Masatoshi Adachi , Tomoaki Karaki Tomoaki Karaki , Wataru Miyamoto Wataru Miyamoto
Published: October 2002

Theoretical and experimental results have shown the potential usefulness of
La3Ga5SiO14 (LGS) for surface acoustic wave (SAW) applications.
The existence of orientations with zero-temperature coefficient of delay
(T
C
D) have been calculated by the computer analysis.
A simulation of the temperature-compensated Rayleigh SAWs
located around both (0°, 140°, 25°) and
(15°, 151°, 40.5°)
with the Rayleigh SAW velocity v of 2762 and 2860 m/s, coupling coefficient
k
2 of 0.38 and 0.41%, and power flow angle PFA of 2 and 0°,
has been carried out. The Rayleigh SAW velocity v is lower than those of
other SAW materials, which enables miniaturization of
SAW design.
Measurement of Residual Particles by High-Intensity Aerial Ultrasonic Waves
Authors: Ito Youichi , Nakayama Satoshi , Miwa andRyohei
Published: October 2002

When high-intensity aerial ultrasonic waves (with a frequency of approximately
20–50 kHz) are applied to drops of liquid adhering to the surface of an object,
the drops instantaneously atomize and peel off from the object and scatter in the
air. If extremely strong sound waves (approximately 170 dB(sound pressure level; SPL)) are applied, it is also possible to cause the solid particles remaining on the
surface of an object to peel off and scatter in the air. In this report, we describe
a study in which we investigated a new method that uses the above-mentioned effects
produced by aerial ultrasonic waves to quantitatively evaluate the cleanness, with
regard to the particles remaining on their surface, of semiconductor manufacturing
jigs that have been precision-cleaned. This method has various features, including
(1) it can be conducted without touching the target object, (2) it can be used on
a specific area of the object, (3) it does not depend on the shape of the object,
and (4) its measurements can be easily carried out.
An Improved Phased Array Ultrasonic Probe Using 0.91Pb(Zn1/3Nb2/3)O3–0.09PbTiO3 Single Crystal
Authors: Saitoh Shiroh , Takeuchi Takashi , Kobayashi Tsuyoshi , Harada Kouichi , Shimanuki Senji , Yamashita Yohachi
Published: October 2002

A 96-channel phased array probe for echocardiography using a single-plate,
0.91Pb(Zn1/3Nb2/3)O3–0.09PbTiO3 (PZNT 91/9) single-crystal transducer with dimensions of
14×20 mm has been fabricated to realize greater sensitivity and broader bandwidth properties.
The center frequency of the probe, 3.5 MHz, was selected to cover the bandwidths of two
conventional lead zirconate titanate (PZT) ceramic probes with center frequencies of 2.5 and
3.75 MHz. A solder paste was used to connect a flexible printed circuit to the PZNT 91/9
transducer. The echo amplitude of the PZNT 91/9 probe is about 6 dB higher than that of the
two PZT probes, and the fractional bandwidths are 30 and 25 percentage points wider,
respectively. The B-mode image quality of the PZNT 91/9 probe is comparable to that of the
two PZT probes, and the Doppler sensitivity of the PZNT 91/9 probe is almost equal to that of
the 2.5 MHz PZT probe, which means that the PZNT 91/9 probe matches both the penetration
of the 2.5 MHz PZT probe and the resolution of 3.75 MHz PZT probe.
Fundamental Study to Develop Bone-Mimicking Phantom
Authors: Asaba Hirotaka , Ohdaira Etsuzo , Masuzawa Nobuyoshi , Ide Masao
Published: October 2002

Since the recent development of ultrasonic diagnosis of osteoporosis, ultrasonic
examination of bones has received considerable attention. Because of the large
attenuation in bone and large difference in the acoustic impedance between bone and
adjacent tissues, ultrasonic diagnosis of bone is generally difficult to perform. The
purpose of this study was to develop a bone-mimicking phantom for fundamental studies of
ultrasonic diagnosis of bone. The phantom developed here was made of plaster. The
acoustic characteristics on ultrasound of the developed phantom showed fairly good
agreement with bovine cancellous bone, which is analogous to human bone.
Influences of Sputtering Power and Substrate Temperature on the Properties of RF Magnetron Sputtered Indium Tin Oxide Thin Films
Authors: Terzini E. , Nobile G. , Loreti S. , Minarini C. , Polichetti T. , Thilakan P.
Published: October 2002

Indium tin oxide thin films have been deposited on glass substrates using
rf magnetron sputtering at different power densities (0.27–0.80 W/cm2)
and at different substrate temperatures (RT-250) °C. Film structure,
crystallite size and orientation, optical absorption and bandgap have been
studied to characterize the films. Carrier concentration and Hall mobility
have been determined by Hall effect. X-ray diffraction (XRD) analysis
of room temperature (RT) deposited samples
reveals a structural change from amorphous to mixed
amorphous/polycrystalline structure with <100> preferred orientation with
increasing rf power density. The increase in substrate temperature results
in a similar structural evolution from amorphous to a mixed phase followed,
at temperatures higher than 200°C, by a polycrystalline phase
with <111> orientation. The study clearly indicates that ITO films dominated by
oxygen vacancies prefer to grow with <100> oriented crystallites whereas
the <111> oriented films are characterized by a more
effective doping by tin.
Gated Tunneling Structures with Buried Tungsten Grating Adjacent to Semiconductor Heterostructures
Authors: Michihiko Suhara Michihiko Suhara , Lars-Erik Wernersson Lars-Erik Wernersson , Boel Gustafson Boel Gustafson , Niclas Carlsson Niclas Carlsson , Werner Seifert Werner Seifert , Anders Gustafsson Anders Gustafsson , Jan-Olle Malm Jan-Olle Malm , Andrej Litwin Andrej Litwin , Lars Samuelson Lars Samuelson , Kazuhito Furuya Kazuhito Furuya
Published: October 2002

A tungsten (W) grating was fabricated and embedded in GaAs by MOVPE (metal organic vapor phase epitaxy) with the aim of realizing novel applications of ultrafine metal electrodes within semiconductor nanodevices. A combination of W grating and a semiconductor single heterobarrier was used to control the vertical current through the structure based on an effective barrier height modulation controlled by the Schottky depletion around the metal. Transistor operation was observed at room temperature and the mode of operation discussed. Moreover, a gated resonant tunneling transistor was demonstrated at 20 K by integrating GaInP/GaAs double barriers and W grating, including a 1.4 ×1.4 µm2 opening window, to form a vertical channel. The peak-to-valley current ratios were modulated by the gate bias, and fine features due to the lateral potential constriction were observed directly in the current-voltage characteristics.
Duality between Single-Electron Phenomena and Flux Quantization in Mesoscopic Superconductors
Authors: Shingo Katsumoto Shingo Katsumoto , Hideki Sato Hideki Sato , Yasuhiro Iye Yasuhiro Iye
Published: October 2002

In this paper we present experimental results of the order parameter amplitudes in mesoscopic superconductors.
We adopted single-electron transistors to detect the amplitude sensitively and with negligible interference to the mesoscopic superconductivity.
The emphasis is on the high duality between the single-electron phenomena and the flux quantization in mesoscopic superconductors.
Suppression of Self-Frequency-Scanning and Brightness Improvement of a Broad-Stripe Laser Diode using Phase Conjugate Feedback
Authors: Hatano Satoshi , Omatsu Takashige , Tateda AkiraHasegawa , Ogura Iwao
Published: October 2002

We present a new technique for suppressing the self-frequency-scanning in a
single-stripe high power laser diode, known as a broad-stripe laser diode (BS-LD) with
phase conjugate feedback. The lasing frequency was locked at the central wavelength
of 808.7 nm within 0.1 nm for 20 min. The BS-LD was then operated in a narrow-band with a 0.4 nm line width and generated a single-lobed near-field radiation with a
narrow divergence.
Evaluation of the First-Order Hyperpolarizability Tensor of Bent Molecules by Means of Hyper-Rayleigh Scattering Method
Authors: Fumito Araoka Fumito Araoka , Byoungchoo Park Byoungchoo Park , Yoshitaka Kinoshita Yoshitaka Kinoshita , Ken Ishikawa Ken Ishikawa , Hideo Takezoe Hideo Takezoe , Jirakorn Thisayukta Jirakorn Thisayukta , Junji Watanabe Junji Watanabe
Published: October 2002

The first-order hyperpolarizabilities βs were
determined by hyper-Rayleigh scattering in two homologous
series of two-dimensional bent molecules with alkyl and alkoxy end chains.
It was found that the β values of alkyl and alkoxy compounds are
nearly the same and increase slightly with increasing chain length
from ca. 10 ×10-30 esu to ca. 40 ×10-30 esu.
Using the β value determined in the present study
and the dihedral angle of the bent molecule,
the tensor elements of β were also determined.
The second-order nonlinear susceptibilities d
33 and d
31
were estimated and compared with an experimental result obtained by a
bulk second-harmonic
generation (SHG) measurement by Macdonald et al.
[Phys. Rev. Lett. 81 (1998) 4408]. This comparison
leads to a conclusion that the high SHG activity in bent molecular
liquid crystal systems is attributed to highly ordered molecules
possessing high hyperpolarizability
in smectic layers.
Preparation of Piezoelectric Ceramic Transformer Operating in Bending Vibration Mode
Authors: Futakuchi Tomoaki , Sugimori Hiroshi , Horii Kazuhiro , Yanagawa Arata , Adachi andMasatoshi
Published: October 2002

A new type of piezoelectric transformer operating in the bending vibration mode was prepared using ceramics with the composition of
Pb[Zr0.48Ti0.42(Mn1/3Nb2/3)0.1]O3, which
showed an electromechanical coupling factor of k
p=0.48 and a mechanical quality
factor of Q
m=2060. The transformer performed at a frequency as high
as approximately 530 kHz and a high power density of 7.9 W/cm3 was
realized.
Molecular Orientation of Liquid Crystal Monolayers on Polyimide Films Exposed to Linearly Polarized UV Light
Authors: Koichi Kumagai Koichi Kumagai , Kenji Sakamoto Kenji Sakamoto , Kiyoaki Usami Kiyoaki Usami , Ryuichi Arafune Ryuichi Arafune , Yoichi Nakabayashi Yoichi Nakabayashi , Sukekatsu Ushioda Sukekatsu Ushioda
Published: October 2002

By using optical second harmonic generation (SHG), we have investigated the molecular orientation of liquid crystal (LC) monolayers in contact with polyimide films exposed to linearly polarized ultraviolet light (LPUVL) at the wavelength of 266 nm.
For different exposures at 3, 8, 20, and 80 J/cm2, the second harmonic (SH) signal from the LC monolayer was measured as a function of the rotation angle of the sample around the surface normal.
The SH signal has no rotation angle dependence, independent of the energy density of exposure.
On the other hand, uniform parallel (homogeneous) alignment of bulk LC was observed for a LC cell made with two polyimide-coated substrates exposed to LPUVL at 8 J/cm2.
From these results we found that the in-plane anisotropy of the LC monolayer in contact with the polyimide film is very small, if any, even though the polyimide film can induce the homogeneous alignment of bulk LC.
The average tilt angle of LC molecules in the monolayers in contact with the polyimide films was also determined.
We found that the average tilt angle of LC molecules measured from the surface normal decreases with the increase of UV exposure.
Sol–Gel Derived Epitaxial MgTiO3 Thin Films
Authors: Lee Jaichan , Choi Chang Won
Published: October 2002

MgTiO3 thin flms have been successfully grown on a sapphire
crystal by the sol–gel process. Epitaxial growth of MgTiO3 thin
films was obtained using magnesium acetylacetonate and titanium
isopropoxide in the sol–gel process. In nonhydrolytic conditions,
the c-axis oriented ilmenite structure of MgTiO3 thin films
developed at the crystallization temperatures 650–800°C with
a 3-fold axis symmetry in the c-plane. These epitaxial MgTiO3
thin films had extremely fine features in
morphology, i.e., a fine grain size of 10–20 nm and a very
smooth surface of 0.9 nm rms roughness. The epitaxial MgTiO3
thin films exhibited a UV absorption edge at 280 nm and were
transparent in the wavelength range of 400–1100 nm. The ordinary
refractive index of the epitaxially grown MgTiO3 thin films was
2.305, very close to the value of single-crystal MgTiO3. This
suggests that the epitaxially grown MgTiO3 thin films are well
crystallized and sufficiently strain-relaxed due to the small lattice
mismatch with Al2O3 substrate.
Lower Temperature Deposition of Polycrystalline Silicon Films from a Modified Inductively Coupled Silane Plasma
Authors: Kazutomo Goshima Kazutomo Goshima , Hirotaka Toyoda Hirotaka Toyoda , Tetsuya Kojima Tetsuya Kojima , Mikihiko Nishitani Mikihiko Nishitani , Masatoshi Kitagawa Masatoshi Kitagawa , Hiroshi Yamazoe Hiroshi Yamazoe , Hideo Sugai Hideo Sugai
Published: October 2002

An inductively coupled plasma (ICP) is successfully modified to deposit polycrystalline silicon (poly-Si) films on a glass substrate (<300°C) with SiH4 diluted by hydrogen.
The modification includes a gas residence time control and a dielectric cover on an internal metal antenna.
A metal antenna discharge in 2% SiH4 at a total pressure of 2.0 Pa results in a monotonically increasing deposition rate up to 0.4 nm/s with a decrease in the residence time to 18 ms.
The dielectric-covered antenna makes the deposition rate two times higher than the metal antenna.
The higher crystallinity of the deposited film is achieved with a lower residence time and/or a smaller percentage of SiH4, both of which decrease the deposition rate.
For example, a 600W 0.3% SiH4 discharge by the dielectric cover antenna gives a poly-Si grain size of 140 nm from the X-ray diffraction (XRD) spectra and a crystallization factor of 0.98 from the Raman spectra.
Solid-State Amorphization in Al/Pd Multilayer during Near-Room-Temperature Molecular-Beam Deposition
Authors: Toshiki Kingetsu Toshiki Kingetsu , Yasuhiro Kamada Yasuhiro Kamada , Masahiko Yamamoto Masahiko Yamamoto
Published: October 2002

We studied the growth behavior and structures of two [Al (t nm)/Pd (0.6 nm)] multilayers (t = 0.4, 0.8) and a single-layered Al film, which were grown on 50-nm-thick (100) Pd buffer layers using molecular-beam deposition. In situ reflection high-energy electron diffraction and ex situ X-ray diffraction analyses revealed the following features. The multilayer of t = 0.4 starting from an Al layer grew epitaxially for the first Al/Pd bilayer but showed an amorphous-like surface structure during growth of the second to fiftieth bilayers. The multilayer had an amorphous structure without compositional modulation despite the growth near room temperature. The multilayer of t = 0.8 showed an amorphous-like surface structure from the first Al layer to about the fiftieth bilayer. This multilayer having 100 bilayers finally consisted of an amorphous matrix with compositional modulation and fine crystallites of B2-type AlPd compound. The Al film changed its surface structure depending on its thickness t: (100) epitaxy for t ≤0.5, nearly amorphous for 0.5 < t < 2.5, and a <111>-oriented fibrous structure for t ≥2.5. The relationships between interdiffusion and solid-state amorphization are discussed.
Gas-Source Migration-Enhanced Epitaxial Growth of GaP, AlP and AlAs
Authors: Nagano Masahiro
Published: October 2002

Gas-source migration-enhanced epitaxial growth of GaP, AlP and AlAs was studied.
The growth rates of layers depend on the flux of the group III source. Reflection high
energy electron diffraction (RHEED) exhibited phosphorus-stabilized reconstruction on
the GaP surface as a (2×4) pattern, while it showed a (1×1) streaky pattern on the
AlP and AlAs surfaces, although RHEED oscillations were observed. The results of X-ray
diffraction rocking curves showed that the flatness of the layers was good. The refractive
indices agreed with the previous data for bulk crystals.
Numerical Analysis of the Nucleation Process for Metallic Clusters in the Ionized Cluster Beam Technique
Authors: Masaaki Sanada Masaaki Sanada , Nobuyuki Donkai Nobuyuki Donkai , Kazumi Nishioka Kazumi Nishioka
Published: October 2002

The nucleation process in the ionized cluster beam technique is
numerically analyzed to clarify the condition for producing metallic clusters.
The mean free path of monomers in the crucible and the Knudsen number
are calculated under experimental conditions
to judge the magnitude of the collision rate of monomers.
The steady-state nucleation rate is calculated
as a function of the crucible temperature and the Mach number
to evaluate the effects of crucible conditions and nozzle geometry
on the nucleation rate.
The numerical results for various metals are consistent with
the existing experiments.