bluuebunny/crossref_metadata_2025 huggingface dataset:
Graded-Index Polymer Optical Fiber with High Thermal Stability of Bandwidth
Authors: Ishigure Takaaki , Sato Masataka , Nihei Eisuke , Koike Yasuhiro
Published: October 2002

The development of the perfluorinated (PF) polymer based graded-index polymer
optical fiber (GI POF) for high-speed data communication is described. It was
experimentally confirmed that gigabit data transmission for 500–1000 m at 1.3 µm
wavelength was achieved by the low-loss PF polymer based GI POF. The thermal
stability of poly (methyl methacrylate) PMMA based GI POF is discussed. We selected
several kinds of dopants that can maintain a high glass transition temperature (T
g) of the
GI POF core. By using the newly selected dopants, we succeeded in maintaining the
parabolic refractive index profile of GI POF with no degradation even at 85 to 90°C for
more than 5000 h.
Effects of Bottom Electrode on the Structural and Electrical Characteristics of Barium Titanate Thin Films
Authors: Shy Hsiou-Jeng , Wu Tai-Bor
Published: October 2002

Barium titanate thin films of 50 nm thickness and having a composition of
Ba(Zr0.12Ti0.88)O3 (BZT) were deposited on different electrodes of LaNiO3 (LNO), Pt
and RuO2 by rf magnetron sputtering at 400°C. Highly crystallized and (100)-oriented
BZT films were formed by deposition on the (100)-textured LNO electrode, but
poorly crystallized films were obtained by deposition on the other two electrodes. The
films deposited on LNO were smooth and had a flat interface that epitaxially bonded
with the LNO electrode. However, the films deposited on Pt or RuO2 were rough and
had a rugged film/electrode interface. High interdiffusion was found at the BZT/RuO2
interface, but not at the other two interfaces. The dielectric constant of the film on
LNO was ∼250, but that of the films on Pt or RuO2 was ∼120. For the former, a high
and stable insulating characteristic against biasing voltage was also found, i.e., a low
leakage current of 10-9 A/cm2 was maintained before reaching a high onset voltage of
5 V. In contrast, the leakage current rapidly increased to >10-7 A/cm2 with increasing
bias to 5 V or 2 V for the films deposited on Pt or RuO2, respectively. The relationship
of current versus time (J–t) measured at 380 K also revealed the superior insulating
property of the film deposited on LNO compared to the other two films.
Leakage Current Characteristics of Lead-Zirconate-Titanate Thin Film Capacitors for Memory Device Applications
Authors: Chen Hong-ming , Tsaur Sheng-wei , Lee Joseph Ya-min
Published: October 2002

The leakage current of ferroelectric thin film capacitors is comprised of electronic conduction
current and polarization current. In this work, the origin of these leakage current components in lead-zirconate-titanate (PZT) thin film capacitors is studied by means of two different methods. The first
method distinguishes the current components by measuring the leakage current with different delay
times. The second method determines the current components by measuring the charging and
discharging currents when a specified voltage is turned on and off. Both measurements show that the
polarization current is dominant in an electric field lower than 100 kV/cm. The polarization current is
modeled using Debye-type electric polarization. The relaxation times and equivalent capacitances of
the polarization current are extracted from the discharging current. The electronic conduction current
obtained by measuring the leakage current with long delay time can be explained to be due to ohmic
conduction in a low field (lower than 40 kV/cm) and Poole-Frenkel emission in a high field (higher
than 40 kV/cm). The total leakage current calculated by the sum of the polarization current and the
electronic conduction current agrees well with the measured result.
Reaction Characteristics between Cu Thin Film and RF Inductively Coupled Cl2 Plasma without/with UV Irradiation
Authors: Seok Kwon Myoung , Yong Lee Jeong , Kang-Sik Choi Kang-Sik Choi , Chul-Hi Han Chul-Hi Han
Published: October 2002

Reaction characteristics between copper (Cu) thin film and inductively coupled Cl2 plasma at room temperature have been studied over a pressure range of 2 – 20 mTorr, an RF inductive power range of 300 – 700 W, a Cl2 flow range of 5 – 30 sccm and a substrate bias range from 0 V to -60 V. The main reaction product was a substoichiometric CuClx(s) layer, and it was found that the chlorine concentration “x” and the formation rate of the CuClx(s) layer were greatly influenced by RF power, dilution gases (N2 or Ar), pressure and Cl2 flow rate. The effect of negative substrate bias was found to enhance the formation rate of CuClx(s) linearly such that the total copper etch rate was increased, while the chlorine concentration “x” was unaffected. It was found that the copper consumption rate for the entire Cu etch reaction was enhanced by UV irradiation by approximately five times. The chloride layer formed upon UV irradiation was found to have a much higher Cl concentration (x>1.0) in CuClx compared to the much lower Cl concentration without UV irradiation, and to be composed of the CuCl2(s) phase and CuCl1(s) phase.
Theoretical Investigation of Total Secondary Electron Yield for Teflon
Authors: Hiro Sanju , Fujii Haruhisa , Palov Alexandre
Published: October 2002

The simplest physical model of the ≈1 eV–2.5 keV electron scattering in insulating polymers is
proposed. The simulation of electron trajectories was performed using Monte Carlo technique. The integral
characteristics of electron scattering such as total secondary electron yield and backscattering coefficients
for Teflon were investigated for 50 eV–2.5 keV electron beams. The difference between theoretical and
experimental data was within 50%.
Axial and Lateral Displacement Measurements of a Microsphere Based on the Critical-Angle Method
Authors: Higurashi Eiji , Sawada Renshi , Ito Takahiro
Published: October 2002

A method has been developed for optically measuring nanometer-scale
displacements of transparent and metal-coated microspheres in both the axial (vertical) and
lateral (horizontal) directions. This method works by detecting changes in the internal
reflection of a laser beam reflected from the microsphere after it passes through critical-angle prisms. For weakly reflective 10-µm-diameter polystyrene microspheres in water
(relative refractive index n=1.2), the detection resolutions as estimated from the full-width at half maximum (FWHM) noise level in the frequency region above 500 Hz in the
axial and lateral directions were experimentally found to be as good as 1.7 and 1.1 nm,
respectively. Furthermore, the lateral displacement resolution (0.2 nm) of a 10-µm-diameter metal-coated microsphere was better than the axial displacement resolution (0.9 nm) of a conventional flat mirror by more than a factor of four.
Comparative Evaluation of Ultrathin Mask Layers of SiO2, SiOxNy and SiNxfor Selective Area Growth of Si
Authors: Hwang Doo-Sup , Yasuda Tetsuji , Ikuta Kazuyuki , Yamasaki Satoshi , Tanaka Kazunobu
Published: October 2002

Ultrathin SiO2 and SiN
x
layers on Si are potential mask materials for
nanoscale selective-area chemical vapor deposition (CVD) in reduced dimension.
This study investigates the mask-material dependence of Si nucleation processes
on these ultrathin layers. Thin layers of SiO2, SiN
x
and SiO
x
N
y
were formed by
plasma oxidation and nitridation. They were subjected to CVD processing
without exposure to air, which prevented the results from being affected by
surface contamination. Incubation time for nucleation was checked by both in-line
Auger electron spectroscopy (AES) and atomic force microscopy (AFM). In
the case of ultrahigh vacuum CVD (UHV-CVD) at 853 K, the incubation time for
nucleation decreased in the order of SiO2, SiO
x
N
y
and SiN
x
. In the case of flow-modulated
plasma-enhanced CVD (FM-PECVD) at 473 K, Si growth did not
depend on the kind of the mask material. Direct electron-beam patterning of this
mask layer is briefly reported. Based on the results presented, a novel bilayer
mask structure is proposed.
C60 Resist Mask of Electron Beam Lithography for Chlorine-Based Reactive Ion Beam Etching
Authors: Matsutani Akihiro , Koyama Fumio , Iga Kenichi
Published: October 2002

We have examined a potential of a C60 film as an electron-beam resist for a chlorine-based reactive ion beam etching mask. The sensitivity of C60 as a negative-type electron beam resist was
∼25 mC/cm2 for monochlorobenzene. The maximum etching rate ratios of GaAs and InP to C60 were 20 and 5, respectively. In addition, we have succeeded in
fabricating micropillars of <0.5 µm in diameter in GaAs with this C60 mask for the first time.
Crystal Structures and Phase Transformation in In2Se3 Compound Semiconductor
Authors: Jiping Ye Jiping Ye , Sigeo Soeda Sigeo Soeda , Yoshio Nakamura Yoshio Nakamura , Osamu Nittono Osamu Nittono
Published: October 2002

Crystal structures and phase transformation in In2Se3 compound
semiconductor have been studied by electron
diffraction, high resolution electron microscopy and X-ray diffraction (XRD) together
with optical absorption measurements.
The time-temperature-transformation (TTT) diagram reveals that there
exist only two phases in In2Se3 and the transformation
temperature is 853 K. The transformation from the high temperature phase to the low
requires a long incubation time for crystal nucleation and
a relatively high temperature for crystal growth.
The low and high temperature phases are the vacancy ordered in screw form (VOSF)
phase and the layer structure phase, respectively. Both phases possess semiconducting
optical properties and are constructed on the basis of
a tetrahedral bonding structure.
The VOSF phase is of a defect wurtzite structure, in which vacancies
on 1/3 of the cation sites are ordered in screw form along the c-axis.
The space group is P61 or P65 with
a=7.14 Å, c=19.38 Å, Z=6.
The layer structure is constructed of five-layer Se–In–Se–In–Se sets and the sets
are linked by weak van der Waals' force with stacking sequence of ABC.
The space group is R3m with a = 4.00 Å,
c = 28.80 Å, Z=3 (indexed in hexagonal system).
In the layer structure, structure vacancies on 1/3 of the cation sites aggregate
to form a vacancy plane for every three In-planes.
The structural difference between the two phases is most clearly characterized
by the difference in coordination numbers of the Se atoms.
Microscopic Analysis of the Degradation Mechanism of Gallium Arsenide Metal-Semiconductor Field-Effect Transistor
Authors: Sasaki Hajime , Hayashi Kazuo , Fujioka Takashi , Mizuguchi Kiyoshi , Yea Byeongdeok , Osaki Tomoyuki , Sugahara Kazunori , Konishi Ryosuke
Published: October 2002

The microscopic degradation mechanism of the recess surface of GaAs metal-
semiconductor field-effect transistor (MESFET) after a long duration aging is analyzed using a
transmission electron microscope (TEM), Raman scattering and several other analytical
methods. Crystallographic arsenic (As) and amorphous gallium (Ga) precipitated after the aging
test. Raman scattering during device operation indicates that the temperature of the drain side is
higher than that of the source side. Light emission by hot carriers is observed at the drain side
of the device during operation. The degradation of the device is accelerated by the hot carriers
generated by a thermionic field emission at the high-temperature drain side.
Dynamics of Charge Storage and Interaction of Microwaves with Silicon-Integrated Surface Oriented Structures
Authors: Koshevaya Svetlana , Tecpoyotl Margarita , Hayakawa Masashi , Grimalsky Vladimir , Kishenko Yaroslav
Published: October 2002

This article focuses on the problem of injection of charges into the i-region of a surface-oriented p-i-n
structure. This structure is very promising for detection and modulation of millimeter and
submillimeter wave range. Both numerical and experimental investigations of the dynamics of charge
storage and interaction of microwaves with integrated surface oriented p-i-n structure with “deep”
injecting junctions are presented.
Single-Layer High-TcSuperconducting Quantum Interference Device Magnetometer with Double-Pickup-Coil Configuration
Authors: Yokosawa Koichi , Maruyama Emi , Ahmad Rashdi Shah , Oyama Hiroshi , Kuriki Shinya , Suzuki Daisuke , Koyanagi Masao
Published: October 2002

We propose a new configuration for direct-coupling-type high-Tcsuperconducting quantum interference device (SQUID) magnetometers consisting of two pickup coils per SQUID on a bicrystal substrate. The SQUID and pickup coils can be arranged symmetrically without covering the bicrystal line on the substrate. This configuration should produce a large coupling coefficient from the pickup coil to the SQUID, and thus a large effective pickup area. First, we optimized the structure and dimensions of the pickup coils using an analogous model made of normal metal. Second, we fabricated SQUIDs for this configuration, in which the slitlike holes were located parallel to the bicrystal line. We also fabricated magnetometers consisting of pickup coils and SQUIDs of this configuration from YBCO film on bicrystal 10 mm × 10 mm SrTiO3substrates. An effective area of 0.42 mm2has been achieved, which was measured by applying an external magnetic field.
Optical Bistability in a Semiconductor Etalon with Nonlinear Integrated Mirrors
Authors: Yoon Tae-Hoon , Shin Dong-Seob , Kim Dug-Bong , Kim Jae Chang , Kim Sun Ho
Published: October 2002

We have shown theoretically that a semiconductor etalon exhibits
optically bistable behavior at a lower input light intensity when the two
mirrors as well as the spacer layer are nonlinear.
Electrooptical and Response/Relaxation Properties of Liquid Crystal Cells in In-plane Switching Mode with Polyvinylcinnamate Photoinduced Alignment Layer
Authors: Ying Zhou Ying Zhou , Susumu Sato Susumu Sato
Published: October 2002

Using polyvinylcinnamate (PVCi) photoinduced alignment layers and rubbed polyvinylalcohol (PVA) alignment layers, we produced PVCi-PVA and PVA-PVA in-plane switching (IPS) cells. Transmission properties of the two kinds of IPS-mode cells show that it is possible to decrease the driving voltage for the IPS-mode cell with a weak anchoring alignment surface. The response times of the PVCi-PVA cells are almost the same as those of the PVA-PVA cells, however, the measurement results of the relaxation times for the PVCi-PVA cells indicate that they depend on the time of the voltage applied, and the relaxation times increase with the increase of the applying time. Furthermore, we investigate the decline effect of the twist angle of a PVCi-PVA cell with time after a voltage has been applied for a very long time and then removed.
Preparation of Oxygen-Containing Pt and Pt Oxide Thin Films by Reactive Sputtering and Their Characterization
Authors: Yoshio Abe Yoshio Abe , Hideto Yanagisawa Hideto Yanagisawa , Katsutaka Sasaki Katsutaka Sasaki
Published: October 2002

Oxygen-containing Pt and Pt
oxide thin films were
prepared by reactive sputtering in Ar and O2 gas atmosphere and effects
of oxygen flow ratio on crystallinity, chemical bonding state and
resistivity were studied.
Polycrystalline oxygen-containing Pt and amorphous Pt oxide thin films were obtained
at O2
flow ratios below 20% and above 30%, respectively. It is confirmed that
these films are composed of the mixture of Pt, PtO and PtO2 and the oxygen
content in these films
increases with an increase in the O2 flow ratio.
Though PtOx films with x ≤0.6 show low resistivity with metallic
conduction, those with higher oxygen content show semiconducting
characteristics and their
resistivity increases with increasing oxygen content.
Composition Control of Barium Strontium Titanate Thin Films Prepared by Chemical Vapor Deposition
Authors: Kiyotoshi Masahiro , Eguchi Kazuhiro , Imai Keitaro , Arikado Tsunetoshi
Published: October 2002

Composition control of barium strontium titanate thin films
prepared by chemical vapor deposition using Ba(THD)2, Sr(THD)2, and
Ti(THD)2(i-OC3H7)2 (THD: 2,2,6,6-tetramethyl-3,5-heptanedionate) has
been studied by investigating the effects of deposition temperature and
the supply rates of metal sources. Although there were complicated
correlations among the deposition rates of Ba, Sr, and Ti under
kinetically limited conditions, the deposition rate ratio of Ba/Sr was
linearly related to the partial pressure ratio of Ba(THD)2/Sr(THD)2, and
the ratio of Ti/(Ba+Sr) spontaneously approaches unity. In order to
explain these characteristics, we proposed a model wherein the THD
complex of Ba or Sr reacts with the THD complex of Ti and generates a
dimer such as (THD)2Ba–O–Ti(THD)2, and this dimer becomes the
dominant precursor for chemical vapor deposition (CVD) under kinetically limited conditions.
Mixing/Resonance of Electronic States and Optical Nonlinearity in a GaAs/AlGaAs Asymmetric Triple Quantum Well Structure
Authors: Hyung Soo Ahn Hyung Soo Ahn , Masahito Yamaguchi Masahito Yamaguchi , Nobuhiko Sawaki Nobuhiko Sawaki
Published: October 2002

The input power dependence on the transmission of a light through a GaAs/AlGaAs asymmetric triple quantum well (ATQW) shows strong nonlinearity at 77 K, the behavior of which depends on the wavelength of the input light. By studying the relation of nonlinearity to the photoluminescence spectra, the resulting phenomenon is attributed to the Stark shift and change of the optical oscillator strength which is due to the triple resonance of the electronic states. The triple resonance is induced by the temporal separation of photo-excited electrons and holes.
Anisotropic Strain Estimated from Lattice Parameters Measured by Bond Method Using X-Ray Diffraction, in Molecular Beam Epitaxy-grown GaAs/Si(001)
Authors: Yodo Tokuo
Published: October 2002

x-, y- and z-components of lattice parameters on GaAs in GaAs films grown on Si(001) substrates by molecular-beam epitaxy have been experimentally measured from (004), (115) and (404) diffractions of GaAs by the Bond method using X-ray diffraction (XRD). The anisotropic strain on GaAs is estimated from the difference in each component of lattice parameters between the film and the GaAs bulk crystal. In-plane components of mechanical stress on GaAs are estimated from the measurement of substrate curvature using double-crystal XRD. The elastic strain is also estimated from the stress, assuming an elastic distortion of the lattice. However, it does not coincide with the strain derived from lattice parameters. The difference in the strain estimated by the two methods is largely especially near the interface, indicating strong, anisotropic and plastic deformation of the lattice, so that it can no longer be regarded as an elastic body. It is probably caused by lattice and stress relaxation related to the anisotropy of dislocations in the film.
Lattice Strain in AgGaS2 Epitaxial Layers Grown on GaAs (100) by Multisource Evaporation
Authors: Nozomu Tsuboi Nozomu Tsuboi , Masaki Kurasawa Masaki Kurasawa , Satoshi Kobayashi Satoshi Kobayashi , Koichiro Oishi Koichiro Oishi , Futao Kaneko Futao Kaneko
Published: October 2002

Lattice strain in AgGaS2 epitaxial layers of different thicknesses,
which are grown on GaAs (100) by the multisource evaporation method,
is described.
Biaxial compressive mismatch strain in thin layers relaxes with increasing
layer thickness, and biaxial tensile thermal strain becomes dominant in
thick layers. The thin AgGaS2 epitaxial layers are completely
oriented toward the c-axis, but the thick layers contain
180°-rotated { 112 } twin crystals.
The generation of twin crystals is considered to cause partial relaxation of
the thermal strain. The observed variation in the A1-mode frequency
with thickness is fully explained by considering the layer thickness dependence
of the lattice strain.
Full width at half-maximum of the A1-mode Raman scattering line is
affected by the spatial inhomogeneity of the strain magnitude in the depth
direction.
Raman scattering measurement of the A1 mode can be used as a
sensitive technique to evaluate the lattice strain in AgGaS2.
Tunneling Current and Surface Potential Simultaneous Measurement Using a Scanning Probe
Authors: Majima Yutaka , Miyamoto Shin-ichiro , Oyama Yutaka , Iwamoto Mitsumasa
Published: October 2002

A new simultaneous measuring system for tunneling current and surface
potential has been developed. The distance (d) between a sample and an
electrochemically etched tungsten tip is changed sinusoidally with high precision. The
tunneling current flows periodically in accordance with the vibration of the tip when d
becomes as small as a few nm. The surface potential is measured using the principle of
the Kelvin method in which the displacement current due to the presence of surface
potential and the change in capacitance difference between the tip and the sample is
detected. Simultaneous measurement of the tunneling current and the displacement
current has been attained by utilizing their phase difference in tip vibration. The method
for determining the tip radius and d is also presented.
Plasma Opening Switch Using Plasmas Produced by a Pulsed CO2 Laser
Authors: Ihara Satoshi , Mori Satoshi , Ishimine Masashi , Satoh Saburoh , Yamabe Chobei , Akiyama Hidenori
Published: October 2002

Plasma opening switches were studied using laser-produced plasmas. In this
paper, a CO2 laser (5 J/pulse, 5.5 MW peak power and 10.6 µm wavelength) was
used as the plasma source of a plasma opening switch (POS). The plasma
parameters were measured using a Faraday cup, a Langmuir probe and a
monochromator. It was found that ions with fast flow velocity are required to
obtain a short opening time, and thermalized plasma with low velocity lengthens
the opening time. However, POS operation was improved by switch modification
despite the existence of thermalized plasmas.
Electrical Evaluation of Sidewall Damage Caused by CH4/H2 Reactive Ion Etching
Authors: Yuda Masahiro , Kondo Susumu , Noguchi Yoshio , Kishi Kenji
Published: October 2002

Electrical properties of p-n junction mesa diodes damaged at the sidewalls
by reactive ion etching (RIE) with a mixture of methane (CH4) and hydrogen
(H2) were investigated. An InAlAs/InP/InAlAs double heterostructure was
used to suppress the n= 1 diffusion current and, consequently, to study the n\cong 2 recombination current at the mesa-etched sidewall. The extent of
damage layer at the sidewall was clarified from the dependence of n\cong 2
recombination current on the wet etching. Damaged-layer thickness of 60
to 90 nm was estimated from a comparison with the n\cong 2 recombination
current of wet-etched mesa diode.
Diffusion and Electrical Properties of Iron-Related Defects in N-Type Silicon Grown by Czochralski- and Floating Zone Method
Authors: Shuji Tanaka Shuji Tanaka , Hajime Kitagawa Hajime Kitagawa
Published: October 2002

Diffusion and electrical properties of iron-related defects
in n-type silicon are studied in Czochralski (CZ) and floating
zone (FZ) silicon by means of deep level transient spectroscopy
and the Hall effect. Introduction and annealing behaviors of
electrically active iron-related defects reveal that these
defects can be related to complexes containing interstitial
iron atoms. The formation of iron-related defects at high
temperatures includes defect reaction processes such that
the observed complexes could be due to the intermediate
states in consecutive reactions of iron-related complex
formation. The electrically active complexes are independent
of phosphorus or oxygen atoms. The iron-related defects
observed in CZ silicon are identical to those observed in FZ silicon.
Band Structure of GaP1-xNx(x= 0.25, 0.5, 0.75) Ordered Alloys: Semiempirical Tight-Binding Calculation
Authors: Miyoshi Seiro , Onabe Kentaro
Published: October 2002

A semiempirical tight-binding calculation of the electronic structure of GaP1-x
N
x

ordered alloys (x=0.25, 0.5, and 0.75) has been performed. The bowing parameter of the
band gap is extremely large (7.6 and 3.2 eV for the \varGamma–X and the \varGamma–\varGamma transitions,
respectively), which explains the experimental band gap reduction with increasing x when
x<0.03 as observed by photoluminescence (PL) measurements [S. Miyoshi, H. Yaguchi,
K. Onabe, R. Ito and Y. Shiraki: Appl. Phys. Lett. 63 (1993) 3506]. We have clarified
that the large bowing originates from the large valence band (VB) offset between GaP
and GaN (3.66 eV by Harrison's rule). The calculated band lineup of the GaP1-x
N
x
alloy
indicates that not only the GaP1-x
N
x
–GaP heterojunction but also the GaP1-x
N
x
–GaN
heterojunction will show a type-II transition. The electronic structures of GaAs1-x
P
x
and
GaAs1-x
Sb
x
ordered alloys have also been calculated, and the values were consistent with
the experimental band gap. The consistency confirms the validity of our calculation.
The calculation is also applied to the electronic structure of a GaAs1-x
N
x
ordered alloy (x=0.25, 0.5, and 0.75) which is also found to have large bowing parameters (4.0, 8.5, and
6.2 eV for the \varGamma–\varGamma, \varGamma–X, and \varGamma–L transitions, respectively) probably due to the large VB offset between GaAs and GaN.
Initial Growth of Polycrystalline Silicon Films on Substrates Subjected to Different Plasma Treatments
Authors: Hasegawa Seiichi , Uchida Noriyuki , Takenaka Satoshi , Inokuma Takao , Kurata Yoshihiro
Published: October 2002

Undoped 0.2-µm-thick polycrystalline Si (poly-Si) films were deposited on fused quartz substrates by
plasma-enhanced chemical vapor deposition from a SiH4–H2 mixture. All films were prepared under the same
deposition conditions, just after the substrates were exposed for 1 min to CF4–He plasma excited with various rf
powers. Poly-Si films with improved crystallinity and large grains were obtained when the films were deposited
on substrates with the proper degree of surface roughness of uniform size and shape. These films were also
found to have lower values of stress and higher values of g, as compared with those of poly-Si films on
substrates with a flat surface or an extremely rough surface. The X-ray diffraction (XRD) spectra exhibited only
the <110> texture, and the intensity was proportional to the third power of the average grain size estimated from the width values of the XRD spectra. These results suggested that the growth of grains is three-dimensionally controlled and depends on the surface morphology of the substrates, while the concentration of
grains per unit area is roughly independent of the morphology of the substrates.
Temperature Dependence of the Ideality Factor of Ba1-xKxBiO3/Nb-doped SrTiO3 All-Oxide-Type Schottky Junctions
Authors: Yamamoto Tetsuya , Suzuki Seiji , Kawaguchi Kenichi , Takahashi Kazuhiko
Published: October 2002

Current-voltage measurements were performed on Ba1-x
K
x
BiO3/Nb-doped SrTiO3 (BKBO/STO:Nb) all-oxide-type Schottky junctions in
the temperature range of 30 to 300 K. The relative permittivity ε
r(E, T) of
undoped SrTiO3(110) was measured as a function of both temperature and
electric field. An anomalous increase in ideality factor n(T) and decrease in
zero-bias barrier height Φb0(T) with decreasing temperature were observed
and were analyzed using the interfacial layer model with a thin insulating
interfacial layer present between metal contact (BKBO) and semiconductor
interface (STO:Nb). The increase in n(T) at low temperature can be
explained by taking into account the temperature dependence of the
permittivity of the depletion layer (STO:Nb). The effect of the electric field
dependence of the permittivity of STO:Nb on n(T) is also discussed using
an approximate electric field dependence, ε
r(T, E)=b/(a+E
2)1/2, where a
and b are constants.
Flux Pinning by substitution in Nd1Ba2Cu3Oy Single Crystals
Authors: Pradhan A. K. , Kuroda Kiyoshi , Chen Bo , Koshizuka Naoki
Published: October 2002

Magnetization and magneto-transport studies have been performed on high quality
Nd1Ba2Cu3O
y
(Nd123) single crystals grown by traveling solvent floating zone method in a
reduced oxygen partial pressure. The angle dependent magnetization scales well. The
magnetization loop splits into two peaks for H∥c. The first peak disappears when the c-axis is
tilted away from the field displaying the influence of twin boundary for H∥c. The
magnetotransport measurement by a six-terminal configuration shows correlation of the
vortices along the c-direction of the Nd123 crystal. The pinning force increases markedly in the
twinned crystal in comparison to the detwinned Nd123 crystal. The above measurements along
with the studies of volume pinning forces in twinned and detwinned crystals and their
microstructure reveal that the interplay between the twin planes and the substitutional Nd–Ba
sites are responsible for high pinning in this material, especially in the high field region.
Evaluation of Low-Temperature Specific Heats and Thermal Conductivities of REGa2 (RE=Pr, Nd, Gd, Tb, Dy, Ho and Er) and Dy1-xHoxGa2 (0<x<1) Intermetallic Compounds as Regenerator Materials
Authors: Yagi Wataru , Iwata Hideki , Mizutani Uichiro
Published: October 2002

The low-temperature specific heats of REGa2 (RE=Pr, Nd, Gd, Tb, Dy, Ho and
Er) and Dy1-x
Ho
x
Ga2 (0<x<1) intermetallic compounds are measured over the
temperature range of 1.5–20 K to evaluate their applicability as regenerator
materials. Among them, DyGa2 exhibits a pair of sharp peaks reaching 1.45
and 1.0 J/K cm3 at 6.5 and 9 K, respectively. The double-peak structure is
also observed in the HoGa2 compound and the volumetric specific heat
reaches 0.6 and 0.5 J/K cm3 at 7 and 8.1 K, respectively. The occurrence of a
large magnetic specific heat is attributed to the lifting of the six fold
degeneracy of the ground state and subsequent magnetic structure
modifications below the Néel temperature in these two compounds. The
thermal conductivity of DyGa2 is twice as high as that of Er3Ni. Spherical
DyGa2 powders of 0.2 mm diameter are successfully synthesized and exhibit
good corrosion resistance against moisture. We conclude that the present
Dy1-x
Ho
x
Ga2 (0≤x≤1) compounds are suitable as regenerator materials at
temperatures below 10 K.
Ion Etching of Fused Silica Glasses for High-Power Lasers
Authors: Kamimura Tomosumi , Mori Yusuke , Sasaki Takatomo , Yoshida Hidetsugu , Okamoto Takayuki , Yoshida Kunio
Published: October 2002

Subsurface damage incurred during optical polishing, which is known to lower the laser damage thresholds of fused silica surfaces, was studied. Ceria in subsurface fissures was completely removed (depths up to one thousand Å) using rf-magnetron sputtering without degrading surface roughness. The laser-induced damage threshold of the optical coating deposited on an ion-etched surface was improved by a factor of two compared to that on an unprocessed surface.
Calculation of Nonlinear Susceptibility Tensor Components in Ferroelectrics
Authors: Osman Junaidah , Ishibashi Yoshihiro , Tilley David R.
Published: October 2002

We present the formalism within which all second and third order nonlinear
susceptibility coefficients can be calculated from the Landau expansion for an isotropic
paraelectric phase by means of the Landau-Khalatnikov dynamical equations. Both
first-order and second-order phase transitions are considered. Detailed results are
given for all the second-order coefficients in the ferroelectric phase and for third
harmonic generation, intensity-dependent refractive index and d.c. Kerr effect in both
paraelectric and ferroelectric phases.
Anomalous Dielectric Dispersion in Tantalum Oxide Films Prepared by RF Sputtering
Authors: Miyairi Keiichi
Published: October 2002

Tantalum oxide thin films prepared by rf sputtering show anomalous dielectric dispersion in the
low frequency range. Very high dielectric constant and dielectric loss (tan
δ) are observed in the
frequency range below 10 kHz. The dielectric loss (tan
δ) peak shifts toward higher frequencies
with temperature. In addition, this peak shows strong thickness dependence which excludes the
possibility of ordinal dipolar polarization. These characteristics are explained in terms of interfacial
polarization based on the Maxwell-Wagner mechanism. The thickness of the aluminum oxide
blocking layer on the electrode surface has been evaluated to be approximately 38 nm from
experimental results.
Growth of PbTiO3 Thin Film on Si(100) with Y2O3 and CeO2 Buffer Layer
Authors: Wu Ye-Min , Lo Jyi-Tsong
Published: October 2002

The PbTiO3 thin film was deposited on Si(100) with Y2O3 and CeO2 buffer layers. Y2O3, CeO2 and PbTiO3 layers were fabricated by the in-situ pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) analysis revealed that the Y2O3 and CeO2 layers were (222) and (200) preferential orientation, respectively. PbTiO3 showed (100)+(001) mixed texture on CeO2/Si and polycrystalline on Y2O3/Si, respectively. Characterization of the grazing angle incident X-ray diffraction showed that the stress depth profile of the PbTiO3 thin film on CeO2/Si(100) was not uniform. The secondary ion mass spectroscopy (SIMS) analysis indicated that the CeO2 and Y2O3 layers reduced significantly the interdiffusion of Si atoms into PbTiO3 and that the distributions of Pb and Ti elements were uniform throughout the PbTiO3 layer. The columnar crystallization of CeO2, Y2O3, and PbTiO3 films were observed by scanned electron microsopy (SEM).
Grain-Orientational Dependence of Cristobalite Formation in Polycrystalline β-SiC Films on Thermal Oxidation
Authors: Toshiki Kingetsu Toshiki Kingetsu , Masaharu Takehara Masaharu Takehara
Published: October 2002

We studied the dependence of cristobalite formation on grain orientation of polycrystalline β-SiC films upon thermal oxidation. Sample films with various surface morphologies and microstructures were synthesized on graphite by chemical vapor deposition (CVD), and were oxidized in methane combustion exhaust gas or in air at a pressure of 100 kPa and a temperature of 1773 or 1873 K. SiO2 overlayers formed on the SiC films consisted of amorphous silica and cristobalite. The amount of cristobalite formed was found to increase with increasing content of <111 >-oriented grains on the film surfaces both in methane combustion exhaust gas and in air. We discuss the possibility of epitaxial cristobalite crystallite formation on the {111} surfaces of β-SiC grains and the reasons why <111 >-oriented SiC grains are more likely to form cristobalite despite the pebbled surface of the SiC films, which is commonly seen in CVD-SiC films.
A New Method for Measuring Secondary Electron Emission Yield from Nd Surface Bombarded by Ions from a Laser-Ion Source
Authors: Tamura Koji , Ogura Koichi , Shibata Takemasa
Published: October 2002

A new method to study secondary electron emission has been devised and
secondary electron emission yield from Nd surface bombarded by Nd ions
was measured in the energy range of 0.1–3 keV. A neodymium ion beam was
extracted from a laser-ion source using resonance photoionization, and
bombarded the surface which was continuously covered by Nd atoms. The
variation in ion flux was calibrated by the reference ion signal. Secondary
electron emission is not observed for energies below 0.97 keV. Above the
threshold, secondary electron emission yield increases linearly with the
incident ion energy and becomes 0.17 at 3 keV. These results indicate that
by this method secondary electron emission yield can be measured from a
laser-ion source even when a large incident ion flux variation is present.
Negative Ion Assisted Silicon Oxidation in Downstream of Microwave Plasma
Authors: Koromogawa Takashi , Fujii Takashi , Yamashita Akihito , Horiike Yasuhiro , Shindo Haruo
Published: October 2002

For one application of negative ions in plasma, silicon oxidation at low
temperatures was studied by employing the oxygen negative ions. In the
downstream region of microwave oxygen plasma, the silicon oxidation was
examined under DC bias. The oxidation depth was much larger under the positive
bias than under the negative. It was found that the oxidation depth became
maximum at a certain distance in downstream, and this was consistent with the
distance at which the probe saturation current ratio showed a local minimum,
suggesting a maximum negative ion density at that point. An in-depth analysis by
X-ray photoelectron spectroscopy (XPS) showed that the oxidation proceeded almost linearly with the substrate bias
voltage, and this voltage dependence was also found for the Si substrate at a
temperature of 200°C. The repetition of the short time application of the substrate
bias was found to be effective for further oxidation.
The Spectrum of Electromagnetic Waves in a Planar Gyrotropic Plasma Waveguide
Authors: Ivanov Stefan T. , Nikolaev Nikolay I.
Published: October 2002

A detailed investigation of the spectrum of the waves propagating in
the parallel-plate waveguide is carried out. It is shown that four families
of waves can propagate in the planar gyrotropic plasma waveguide: plasma,
cyclotron, anisotropic and waveguide modes. It is proved that the singular
waves propagate in the crossing points of the waves with the complex zone
boundary. The influence of the width of the waveguide
and the magnetization of the plasma on the spectrum of the waves is analysed.
As a rule the, cut-off frequencies of the propagating modes decrease with an
increase in the width, and increase with the increase of
magnetization. The fields of different kinds of the waves are plotted
and a comparison is made between them. The evolution of the fields
along the dispersion curves is shown.
New Neutral- and Ion-Scattering Spectroscopy as Applied to Selective Adsorption of Hydrogen on Cu–Pt Alloy Surfaces
Authors: Asahata Tatsuya , Kondo Akio , Shimizu Ryuichi
Published: October 2002

A newly developed time-of-flight system equipped with an accelerating tube was
applied to hydrogen adsorption on Cu–Pt alloy surfaces. The simultaneous
measurements of the scattered neutrals, Ne0, and ions, Ne+, from adsorbates have
shown that selective adsorption of hydrogen on Pt atoms does occur on polycrystalline
Cu–Pt alloy surfaces. Correlation of hydrogen coverage with the neutralization of an
ISS signal is also discussed.
Design Rules for High-Brightness Light-Emitting Diodes Grown on GaAs Substrate
Authors: Lee Song Jae
Published: October 2002

By applying the escape cone concepts, basic design rules for high-brightness AlGaAs or InGaAlP light-emitting diodes (LEDs) have been derived and, in addition, their photon output coupling efficiency have been estimated. Based on the design rules, some of the important structures developed thus far have also been evaluated. The design rules that are expressed in relatively simple forms can also be applied to Ga(As)P LEDs based on either homojunction or single heterojunction, except the InGaN LEDs that are usually grown on sapphire substrate.
Correlation Dimensions of Human-Generated Random Numbers
Authors: Shirouzu Shigenori , Tsuda Yasutami , Shirouzu Eiko , Sugano Hisanobu , Nyuryo Koichi , Nishi Yutaka , Inoue Masayoshi
Published: October 2002

We tried to approach the random number generation test as an
application of chaos analysis. The randomness of numbers was well
represented by their correlation dimensions calculated by Judd's method. We
tried four methods of random number generation, and two of them (writing
and verbal) measured the activity of creating randomness in numbers. The
other two methods, which input the numbers to the computers directly,
measured the activity of creating randomness in space. The comparison of
age dependencies indicated that creating randomness in space is easier than
that in numbers.
Effects of Post-Annealing Temperatures and Ambient Atmospheres on the Electrical Properties of Ultrathin (Ba,Sr)TiO3 Capacitors
Authors: Po-ching Chen Po-ching Chen , Hiroshi Miki Hiroshi Miki , Yasuhiro Shimamoto Yasuhiro Shimamoto , Yuichi Matsui Yuichi Matsui , Masahiko Hiratani Masahiko Hiratani , Yoshihisa Fujisaki Yoshihisa Fujisaki
Published: October 2002

Ultrathin (Ba,Sr)TiO3 (BST) film capacitors
with a Pt/Ba0.5Sr0.5TiO3(30 nm)/Pt/TiN/Si structure
were fabricated.
To investigate the effects of annealing temperatures,
capacitors were annealed in flowing Ar or O2 at temperatures
ranging from 400°C to 600°C for 30 min.
The electrical properties of the annealed samples were
strongly dependent on the annealing temperatures.
In the capacitors annealed at 500°C (in Ar and O2)
and 550°C (in O2),
the leakage current decreased to a level of 10-8 A/cm2
when the bias voltage was ±1.5 V.
In the as-deposited sample,
the maximum capacitance appeared at a bias voltage of -1 V.
However, the maximum capacitance increased and appeared at the
zero bias voltage after annealing.
These phenomena are believed to be defect-related
(due to oxygen vacancies).
The annealing atmospheres were also found to have an effect
on preserving the morphology of the Pt electrodes.
Effect of PbTiO3 Seeding Layer on the Growth of Sol-Gel-Derived Pb(Zr0.53Ti0.47)O3 Thin Film
Authors: Kenji Ishikawa Kenji Ishikawa , Kazunari Sakura Kazunari Sakura , Desheng Fu Desheng Fu , Shiro Yamada Shiro Yamada , Hisao Suzuki Hisao Suzuki , Takashi Hayashi Takashi Hayashi
Published: October 2002

Lead zirconate titanate (PZT) films prepared by a sol-gel method
were deposited on Pt/Ti/SiO2/Si substrates with a seeding
layer. A thin PbTiO3 layer, about 30 nm in thickness, was
deposited on the Pt surface as the seeding layer to provide a
nucleation site for PZT crystallization. Strong (001)-preferred
orientation of PZT was observed when the seeding layer was
deposited by pulsed laser ablation at room temperature and
annealed subsequently. This result was explained by a “two-step
growth" model. The texture and microstructure of PZT films can be
controlled by the introduction of a thin seeding layer which
lowers the crystallization temperature and makes it possible to
obtain films composed of very fine grains. The dielectric
properties of ferroelectric materials could be controlled by
changing the grain size.
Optical Bistability in Periodic Channel Waveguides
Authors: Okamoto Toshihiro , Koshimura Kunihiko , Haraguchi Masanobu , Fukui Masuo
Published: October 2002

We have derived nonlinear coupled mode equations appropriate for periodic channel waveguides. These equations contain the three different nonlinear coefficients which were not taken into account in the previous analysis provided by Stegeman et al.. [IEEE. J. Quantum Electron. 18 (1982) 1610.] It has been shown that such nonlinear coefficients lower the switching power for optical bistability generated in the periodic channel waveguides. Dependence of the switching power on the waveguide size, waveguide structure and the grating parameters has been numerically obtained for ridge polydiacetylene (PDA-C4UC4) waveguides.
Preparation of (BaxSr 1-x)TiO 3 Particles by Vapor-Phase Hydrolysis of Precursors Formed from Alkoxide-Hydroxide
Authors: Hayashi Takashi , Shinozaki Hiroshi , Sasaki Kyoichi
Published: October 2002

Solutions of Ba and Sr hydroxides in methanol were allowed to react
with Ti-isopropoxide under conditions of stirring at room temperature for
15 h, and then dried under reduced pressure at ≦40°C, to prepare the
powder precursors of (Ba
x
Sr1-x
)TiO3. The powder precursors prepared thus
were hydrolyzed by introducing nitrogen gas containing water vapor at
100°C. The hydrolyzed products were crystalline nanosize powders of
(Ba
x
Sr1-x
)TiO3 (x=0.7) solid solution with a specific surface area of about
80 m2/g. (Ba0.7Sr0.3)TiO3 bodies sintered at 1275°C showed a relatively
homogeneous microstructure with grain sizes of 0.3–0.6 µm and a relative
density of 97%. They exhibited a dielectric constant of approximately 4000
and a tan
δ of approximately 1% at room temperature.
Electric-Field-Induced Strain in Lead Lanthanum Zirconate Titanate Ceramics
Authors: Akiyama Yoshikazu , Hayashi Takashi
Published: October 2002

The strains induced by a large electric field were measured for the (Pb La) (Zr Ti)O3
solid solution system. Three types of strains which were involved with an inverse
piezoelectric effect, an electrostriction and a forced phase transition, were measured. A
strain of 0.24%, large enough for high performance actuators, was observed under
40 kV/cm for the 8.4/70/30 composition near the rhombohedral-cubic phase boundary.
Influence of Load Resistance on Higher Harmonic Voltages Generated in a Piezoelectric Transformer
Authors: Ishii Keisuke , Akimoto Norihito , Tashirio Shinjiro , Igarashi Hideji
Published: October 2002

The higher harmonic voltages observed in the input side of a Rosen-type piezoelectric
transformer under high power vibration were studied using constant-current method. The
higher harmonic voltages were mainly formed with large second harmonic and small third
harmonic voltages, and showed strong dependence on load resistance. This is due to the
fact that the current component, which drives the transformer through piezoelectricity, is
dependent on the load resistance. This suggestion was confirmed by the measurements of
sample temperature and displacement, and by calculation of the output resistance converted
to the input side.
Field Induced Domains in Antiferroelectric Liquid Crystals
Authors: Tatemori Syuichi , Hiroyuki Uehara Hiroyuki Uehara , Jun Hatano Jun Hatano , Hideo Saito Hideo Saito , Shin'ichi Saito Shin'ichi Saito , Eiji Okabe Eiji Okabe
Published: October 2002

Domain structures at field induced phase transitions of antiferroelectric liquid crystals were investigated by dielectric, electrooptic and light deflection experiments under electric bias fields. Characteristic light deflection phenomena indicating the co-existence of different refractive index domains were observed in antiferroelectric, ferroelectric and ferrielectric phases. Above all, in the chiral smectic Cβ* phase (SmCβ) being considered ferroelectric, the light deflections appeared at zero field after removing the bias and also in two field ranges at which the dielectric constant and the apparent molecular tilt angle showed the step-wise changes. Possible models for the coexisting domains at these induced phase transitions were discussed.
Nonlinear Dielectric Response in Relaxor Ferroelectrics (1-x)Pb(Mg1/2W1/2)O3–xPbTiO3 (x=0.5)
Authors: Iwata Makoto , Kamei Ryuichi , Orihara Hiroshi , Ishibashi Yoshihiro , Ohwa Hidehiro , Yasuda Naohiko
Published: October 2002

The temperature dependence of the third-order nonlinear dielectric constant and the time
dependence of the linear dielectric constant under a biasing field in relaxor ferroelectrics,
(1-x)Pb(Mg1/2W1/2)O3–xPbTiO3 with x=0.5, were measured near the temperature where the
dielectric constant shows a maximum value. It was found that the nonlinear dielectric constant
shows a broad peak without any indication of divergence. It was also found that the dielectric
constant under the biasing field changes slowly with time. The nonlinear response of relaxor
ferroelectrics was discussed.
Improvement of Field-Induced Electron Emission Using Ir or IrO2 Electrode and Ferroelectric Film Coating
Authors: andMasanori Okuyama Yasuhiro Kuratani
Published: October 2002

Field-induced electron emission from a thin plate of
ferroelectric lead zirconate titanate (PZT) ceramic into vacuum
has been improved by coating
the PZT plate with ferroelectric PZT film and using an Ir or
IrO2 film electrode
instead of a Pt electrode.
The PZT film coating enhances the emitted charge and
improves the fatigue property.
The number of the emissions from PZT with the Ir or IrO2 electrode is
improved by more than 4 orders of magnitude in comparison
with that to a Pt electrode.