bluuebunny/crossref_metadata_2025 huggingface dataset:
RF Wave Propagation in Bounded Plasma under Divergent and Convergent Magnetic Field Configurations
Authors: Seiji Takechi Seiji Takechi , Shunjiro Shinohara Shunjiro Shinohara
Published: October 2002

Radio frequency (RF) wave propagation in a bounded plasma (cylindrical shape with a large diameter of 45 cm) produced by a planar, spiral antenna was investigated under divergent and convergent magnetic field configurations. The measured excited magnetic field amplitude and the phase were examined based on helicon wave characteristics, and were consistent with the computed results using the Transport Analyzing System for tokamaK/Wave analysis by Finite element method (TASK/WF) code. The wave propagation region was broadened (focused) in the radial direction with increasing distance from the antenna under the divergent (convergent) field.
The Method to Optimize Gate Oxide Integrity, Hot Carrier Effect and Electro-Static Discharge without Sacrificing the Performance in Sub-Quarter Micron Dual Gate Oxide Process
Authors: Shih Jiaw-Ren , Lee Jian-Hsing , Chen Shui-Hung , Wu Yi-Hsun , Diaz Carlos-H , Liew Boon-Khim , Hwang Huey-Liang
Published: October 2002

In this paper, a simple method to optimize the reliability concerns in the
input/output (I/O) circuits is proposed and verified. Moreover, less masking steps in
the process can be achieved. In the process, super steep retrograde channel is only
implemented at core transistors to have good gate oxide integrity in the I/O regions. A
modified lightly doped drain (LDD) structure formed by arsenic with phosphorus co-implant before poly re-oxidation is used to have long hot carrier lifetime. With the
novel protection structure, the I/O circuits can achieve high electro-static discharge (ESD) failure threshold.
Bulk Laser Damage in CsLiB6O10 Crystal and Its Dependence on Crystal Structure
Authors: Yoshimura Masashi , Kamimura Tomosumi , Murase Kouki , Mori Yusuke , Yoshida Hidetsugu , Nakatsuka Masahiro , Sasaki Takatomo
Published: October 2002

We investigated bulk laser damage in CsLiB6O10 (CLBO) and its relation to crystal structure.
The damage thresholds of CLBO, with the laser irradiation direction ||
<001> and polarization
||
<100>, were determined to be 29 GW/cm2 at 1.064 µm, and 6.4 GW/cm2 at 0.266 µm, using a
single-shot Q-switched Nd:YAG laser in a transverse and a longitudinal single mode, respectively.
It was also found that the laser damage thresholds strongly depend on the direction of laser
irradiation and polarization. The threshold and morphology with crystallographically oriented
cracks suggest that the <001> direction is structurally weak, which is consistent with the result of
the mechanical strength tests.
Effect of Substrate Bias on Si Epitaxial Growth Using Sputtering-Type Electron Cyclotron Resonance (ECR) Plasma
Authors: Gao Junsi , Nakashima Hiroshi , Wang Junli , Iwanaga Kanako , Gao Dawei , Furukawa Katsuhiko , Muraoka Katsunori
Published: October 2002

Control of the energy of ions hitting the substrate during in situ cleaning
and deposition was found to be very important for deposition of epitaxial Si
thin film. This was studied by applying a substrate bias in the range of -30 to +30 V in a sputtering-type electron cyclotron resonance (ECR) plasma system.
During in situ cleaning, positive bias voltage reduced the ion bombardment
energy, and resulted in epitaxial deposition of Si crystal film even at a low
gas pressure of 0.8 mTorr, at which epitaxial deposition was not possible
previously. During deposition, obvious improvements in the crystallinity of
the epitaxial Si film were achieved when the ion energy was reduced by applying a
positive bias. On the other hand, application of a negative bias for the
deposition process resulted in amorphous film even when deposition was
performed at the high gas pressure of 1.7 mTorr, at which epitaxial deposition was
possible previously.
Dependence of Crystal Quality on Residual Strain in Strain-Controlled Thin AlN Layer Grown by Metalorganic Vapor Phase Epitaxy
Authors: Ishihara Yoshiyuki , Yamamoto Jun , Kurimoto Makoto , Takano Takayoshi , Honda Tohru , Kawanishi Hideo
Published: October 2002

Strain-controlled AlN layers were grown on (0001) 6H–SiC with a (GaN/AlN) buffer
layer by metalorganic vapor phase epitaxy using an alternating-source-feeding technique (ASF).
The successful strain and quality control of the thin AlN layer were experimentally demonstrated
down to 0.05 µm by changing the growth conditions of the (GaN/AlN) buffer layer. The
quality of the AlN layer was evaluated by not only X-ray diffraction (θ-2θ) but an X-ray
rocking curve (ω-scan) from the viewpoint of c-axis tilting. The crystal quality was dependent
on the residual strain in the AlN layer. The (GaN/AlN)-buffer layer is effective in improving the
quality of the AlN layer.
Influences of Pump-Beam Focusing Conditions on a Laser-Diode-Pumped Microchip Nd:YVO 4 Laser
Authors: Siao-Lung Hwong Siao-Lung Hwong , Wang-Lin Tsai Wang-Lin Tsai , Tsong-Shin Lim Tsong-Shin Lim , Jyh-Long Chern Jyh-Long Chern
Published: October 2002

The input-output characteristics of a laser-diode-pumped
microchip-type Nd:YVO4 solid-state laser under different
pump-beam focusing conditions are investigated. The beat
phenomenon due to the mismatch between the spot sizes of the pump
beam and the lasing mode is also explored and analyzed.
First Observation of Small Fractures on a Human Dried Proximal Phalanx by Synchrotron X-Ray Interference Radiography
Authors: Mori Koichi , Hyodo Kazuyuki , Shikano Naoto , Ando Masami
Published: October 2002

By taking photographs using wiggler synchrotron radiation (SR),
clear images of fine fissures on a human dried proximal phalanx were
obtained. This has never been achieved by the conventional X-ray
method. The 40 mm×40 mm exposure field used to cover
the object was prepared by magnifying the original SR beam cross
section (7 mm×7 mm) with two successive asymmetric
reflections of Si crystals. The width of the fissures images was
approximately 20 µm on medical X-ray film. These images can be
explained by X-ray phase contrast. This new method may enable an
accurate diagnostic method in the field of orthopedics, such as that
for small fractures associated with a bruise.
Specular Surface Morphology of 4H–SiC Epilayers Grown on (112̄0) Face
Authors: Chen Zhi Ying , Kimoto Tsunenobu , Matsunami Hiroyuki
Published: October 2002

4H–SiC epitaxial growth on 4H–SiC substrates with (11̄00) and (112̄0) faces, which are
perpendicular to the (0001) face, has been investigated. These epilayers are different in
surface morphological structure from those grown on the conventional (0001) face. An
extremely smooth surface can be obtained on (112̄0) without macrosteps and triangular
defects, which are often observed for epilayers grown on the off-axis (0001) face. The (112̄0)
epilayers exhibit one-order-of-magnitude lower surface defect area (0.010%) than the (0001)
epilayers. In contrast, large elongated surface defects are observed for epilayers grown on
(11̄00), probably due to the formation of stacking faults. The different arrangement of
adatoms on the (11̄00) and (112̄0) faces may be responsible for the stacking fault formation
on the (11̄00) face.
Second-Order Transition of Ferroelectric and Antiferroelectric Liquid Crystals in the Electric Field
Authors: andMamoru Yamashita Satoshi Tanaka
Published: October 2002

The behavior of ANNNI (axial next-nearest neighbor Ising) model with the third nearest neighbor interaction
in the presence of an external field is studied to clarify the mechanism of phase transitions occurring in antiferroelectric smectic liquid crystals. The continuous transitions driven by the external field are
shown to occur from the ferrielectric phases to the ferroelectric one.
By applying the results to the V-shaped response of the transmittance of
light to the electric field observed by Seomun et al. [Mol. Cryst., Liq. Cryst.
303 (1997) 181], this phemonenon isconcluded to be attributed to the competition between ferroelectric and
antiferroelectric interactions assisted by the weakened interlayercoupling of smectics.
Time Response of One-Dimensional Photonic Crystals with a Defect Layer Made of Semiconductor Quantum Dots
Authors: Tsurumachi Noriaki , Abe Makoto , Arakawa Mariko , Yoda Takuya , Hattori Toshiaki , Qi Jifa , Masumoto Yasuaki , Nakatsuka Hiroki
Published: October 2002

The effective optical nonlinearity of semiconductor quantum dots can be
enhanced in one-dimensional photonic crystal structures. We have fabricated a
one-dimensional photonic crystal with a structural defect which is made of CdSe quantum
dots. Besides the enhancement of degenerate four-wave mixing efficiency, a fast
response of transient population grating in an order of a picosecond was obtained in the
one-dimensional photonic crystal. This structure can be used as a future photonic device
with high nonlinearity and fast response.
Optical Transitions of the Mg Acceptor in GaN
Authors: Hofmann Detlev M. , Meyer Bruno K. , Leiter Frank , von Förster Walter , Alves Helder , Romanov Nikolai , Amano Hiroshi , Akasaki Isamu
Published: October 2002

We report on the optical transitions of the neutral, paramagnetic Mg acceptor in GaN. Its
identification is based on the magnetic circular dichroism of the absorption combined with
optically detected magnetic resonance (ODMR). Close to the band-gap energy, the transition from
the Mg0 ground state to the neutral-acceptor-bound exciton state (A0X) is observed. In addition,
the hole-ionisation transition Mg0+hν→Mg-+h is detected in the infrared spectral range.
The g-values and the anisotropy of the Mn acceptors agree with those derived by luminescence-detected ODMR.
Etching Behavior and Damage Recovery of SrBi2Ta2O9 Thin Films
Authors: Lee Won-Jae , Cho Chae-Ryong , Kim Shi-Ho , You In-Kyu , Kim Bo Woo , Yu Byoung-Gon , Shin Chang Ho , Lee Hee Chul
Published: October 2002

The etching and ferroelectric properties of SrBi2Ta2O9 (SBT) thin films prepared by metal
organic decomposition (MOD) were investigated. It was observed that the etching rates of
SBT thin films varied with the etch parameters. The etching rate of SBT in gases with Ar
added is higher, which indicates that the physical bombardment could be more efficient in
SBT etching. We also investigated the influence of etching damage in SBT films during the
reactive ion etching (RIE) process on the electrical properties of ferroelectric materials.
Reversion of Photoalignment Direction of Liquid Crystals Induced by Cinnamate Polymer Films
Authors: Obi Masaki , Morino Shin'ya , Ichimura Kunihiro
Published: October 2002

The difference in the surface-assisted in-plane photoalignment of a nematic liquid
crystal between poly[methyl (p-methacryloyloxy)cinnamate] (pCin0) and poly[methyl (p-methacryloyloxyethoxy)cinnamate] (pCin2) in a film state is described. Irradiation of a
film of pCin2 with linearly polarized 313 nm light generated homogeneous alignment of
the liquid crystal in the direction parallel to the electric vector of the light. On the other
hand, the direction of photoalignment induced by a film of pCin0 was perpendicular to the
electric vector of the light in the early stage of photoirradiation, with subsequent reversion
to parallel alignment. The mechanism of photoalignment reversion was discussed on the
basis of the spectral analysis of product distribution of the cinnamate chromophores in the
film state. The perpendicular orientation of the liquid crystal is due to axis-selective E-to-Z photoisomerization, whereas the consequent alignment reversion stems from the
predominant contribution of axis-selective formation of photodimer(s).
High Quantum Efficiency in Organic Light-Emitting Devices with Iridium-Complex as a Triplet Emissive Center
Authors: Tsutsui Tetsuo , Yang Moon-Jae , Yahiro Masayuki , Nakamura Kenji , Watanabe Teruichi , Tsuji Taishi , Fukuda Yoshinori , Wakimoto Takeo , Miyaguchi Satoshi
Published: October 2002

Multilayer organic light-emitting devices with phosphorescent guest emitter,
tris(2-phenylpyridine) iridium doped in a host 4,4′-N,N′-dicarbazol-biphenyl layer were prepared.
The device with the 6.5 wt% guest emitter exhibited external quantum efficiency and power
luminous efficiency of 13.7% and 38.3 lm/W, respectively at the luminance of 105 cd/m2
driven at the voltage of 4.0 V and current density of 0.215 mA/cm2. The half decay lifetime
under continuous constant-current driving for the initial luminance of 500 cd/m2 was 170 h.
Fabrication and Characterization of Artificial Crystal Originated Particles
Authors: Bearda Twan , Mertens Paul W. , Heyns Marc M. , Schmolke Rüdiger
Published: October 2002

Crystal Originated Particles on silicon substrates were imitated by anisotropic etching of pits in the wafer surface. The effect of these artificial defects on the gate oxide in Metal-Oxide-Semiconductor devices was studied. The results show a combined effect of local oxide thinning and electric field distortion on the electrical characteristics of the gate oxide.
An AlGaAs/GaAs Tunnel Diode Integrated with Nanometer-Scale Atomic Force Microscope Tip-Induced Oxides
Authors: Okada Yoshitaka , Iuchi Yoshimasa , Kawabe Mitsuo , Harris James S. , Jr. Jr.
Published: October 2002

We have fabricated and investigated the fundamental electron transport
properties of a two-terminal tunnel diode, which consisted of a
two-dimensional electron gas channel formed at an AlGaAs/GaAs heterojunction
by molecular beam epitaxy and nanometer-scale oxides locally generated by
using an atomic force microscope (AFM). The AFM-generated oxides were
adopted successfully as integral tunnel barriers for electron transport, and
single electron transport and Coulomb blockade regimes were observed in a
quantum dot tunnel diode structure.
Dynamic Gain Equalized Hybrid Optical Amplifier Composed of Erbium Doped Fiber Amplifier and Semiconductor Optical Amplifier
Authors: Cho Ho Sung , Lee Dong Ho , Kim Hyang Kyun , Lee Sang Soo
Published: October 2002

We propose a new hybrid optical amplifier utilizing two-stage
configuration with a silica-based Erbium doped fiber amplifier (EDFA)
and a semiconductor optical amplifier, in which the gain profile can be
equalized dynamically against the input signal level. Proposed hybrid
optical amplifier has gain excursion of less than 1dB over the 27 nm
(1534 nm–1561 nm) wavelength range, for the input signal power of -18 dBm∼-23 dBm per channel.
Growth of InP Islands on LaF 3/InP(111)B Heterostructures by Molecular Beam Epitaxy
Authors: Sayuri Ritchie Sayuri Ritchie , Mario Beaudoin Mario Beaudoin , Thomas Tiedje Thomas Tiedje , Tom Pinnington Tom Pinnington
Published: October 2002

InP islands have been grown on LaF3/InP(111) heterostructures by molecular
beam epitaxy. The InP islands have been imaged by atomic force microscopy and scanning
electron microscopy and are observed to be faceted with three-fold symmetry as expected for (111)
orientation. High-resolution X-ray diffraction shows that the LaF3 substrate layer is a high
quality epitaxial film. A small broadening of the InP substrate diffraction peak is interpreted as
being due to inhomogeneous strain associated with the InP islands and differential thermal contraction
of the LaF3 film during cooling.
Initial Measurements from an Ultrashort-Pulse Reflectometer on GAMMA 10
Authors: Kubota Shigeyuki , Onuma Tsuyoshi , Katoh Masayuki , Mase Atsushi , Tokuzawa Tokihiko , Oyama Naoyuki , Itakura Akiyosi , Hojo Hitoshi , Bruskin Leonid G. , Tamano Teruo , Yatsu Kiyoshi , Domier Calvin W. , Jr. andNeville C. Luhmann,
Published: October 2002

Initial results from an ultrashort-pulse reflectometer
on the GAMMA 10 tandem mirror are
presented. The diagnostic uses an impulse generator (8 V, 65 ps full-width
at half maximum) as its microwave source, and the four-channel receiver system
measures the time-of-flight for ordinary-mode polarized reflected waves at
8, 9, 10 and 11 GHz. The reflectometer tracks electron density fluctuations
well over portions of the discharge, while overall values of the time-of-flight
are in rough agreement with calculated values using Abel-inverted profiles
from interferometry data. These results demonstrate the potential of the
current system for time-resolved electron density profile measurements on
GAMMA 10.
Large Free-Standing GaN Substrates by Hydride Vapor Phase Epitaxy and Laser-Induced Liftoff
Authors: Michael K. Kelly Michael K. Kelly , Robert P. Vaudo Robert P. Vaudo , Vivek M. Phanse Vivek M. Phanse , Lutz Görgens Lutz Görgens , Oliver Ambacher Oliver Ambacher , Martin Stutzmann Martin Stutzmann
Published: October 2002

Free-standing GaN, nearly equal in area to the original
2 inch wafer, was produced from 250–300 µm thick GaN films
grown on sapphire by hydride vapor phase epitaxy (HVPE). The thick
films were separated from the growth substrate by laser-induced
liftoff, using a pulsed laser to thermally decompose a thin layer
of GaN at the film-substrate interface. Sequentially scanned
pulses were employed and the liftoff was performed at elevated
temperature (>600°C) to relieve postgrowth bowing. After
liftoff, the bow is only slight or absent in the resulting free
GaN.
6H to 3C Polytype Transformation in Silicon Carbide
Authors: Vlaskina Svitlana I. , Shin Dong Hyuk
Published: October 2002

The conditions for the polytype transformation from 6H-SiC to 3C-SiC and
the physical properties of the transformed crystals have been studied. When
6H-SiC crystals are annealed in vacuum for 1 hour at 2180 K or 4 hours at
2080 K, the crystals are completely transformed into 3C-SiC. Shorter annealing
times at these temperatures result in partial transformation. No transformation
occurs below 2080 K or above 2270 K. Physical properties of the transformed
crystals have been studied using X-ray diffraction, photoluminescence, and
optical absorption. The optical bandgap of the transformed 3C-SiC crystal is
2.34±0.02 eV and has much lower carrier concentration ((1–5)×1015 cm-3) than the
initial 6H-SiC crystal (1018–1019 cm-3). The transformation takes place in solid
phase with an activation energy of 140±15 kcal/mol.
Fabrication of Holographic Polymer Dispersed Liquid Crystal (HPDLC) with High Reflection Efficiency
Authors: Tanaka Keiji , Kato Kinya , Date Munekazu
Published: October 2002

We investigated the relationship between the reflection efficiency of a holographic polymer dispersed liquid crystal (HPDLC) and the
liquid-crystal/polymer phase separation structure. A small droplet size and a high droplet density increase the reflection efficiency. This
means that the fabrication of a layerlike phase separation structure is necessary for realizing high reflection efficiency.
Fabrication of Array of Hollow Microcapillaries Used for Injection of Genetic Materials into Animal/Plant Cells
Authors: andHiroyuki Fujita Kyoseok Chun
Published: October 2002

We have proposed a micromachined system with the aim of controlling injection
of DNA into cells. The injection system is composed
of two components: hollow microcapillaries for injection and
microchambers for trapping cells.
The hollow microcapillary array, the most important part of the
system has been fabricated. In this paper, we
present a micromachined DNA injection system and the fabrication of
hollow microcapillary array.
Bosch deep reactive ion etching (RIE) etching was used to etch small, deep holes,
approximately 5 µm in diameter and 100 µm in depth, on a silicon
substrate, and enabled the fabrication of microcapillaries with
microchannels inside. The fabricated hollow microcapillaries
are 1 µm in thickness, 30 µm in length and 5 µm in diameter,
and are made of SiO2. The height of the microcapillaries can be easily controlled. Silicon substrate with microcapillaries is bonded
anodically with a processed glass substrate, and enables the silicon
membrane to endure pressure from outside during DNA injection. By
back-side silicon etching in TMAH solution and making holes on tips of
microcapillaries, the fabrication of hollow microcapillaries is completed.
Hollow microcapillary arrays can also be used in some
applications other than DNA injection, such as microchannels in fluid
delivery systems.
Photoluminescence Properties of Sodium Incorporated in CuInSe2 Thin Films
Authors: Kimura Ryuhei , Mouri Takuhei , Nakada Tokio , Niki Shigeru , Lacroix Yves , Matsuzawa Takeo , Takahashi Kiyoshi , Kunioka Akio
Published: October 2002

CuInSe2 films with Cu/In ratios of m=0.83–0.99 have been deposited on glass
substrates by the co-evaporation method using a bi-layer process. The effects of
sodium in these films have been investigated by comparing the electrical and
optical properties of the films with and without the Na2Se incorporation. Two
donor-acceptor pair emissions, [D, A]α at 0.89–0.94 eV and [D, A]β at 0.84–0.87 eV,
were typically observed in the photoluminescence spectra. The relative intensity of
[D, A]α to [D, A]β was found to depend strongly on both the Cu/In ratio and Na
incorporation. For the films with m=0.94, [D, A]α was predominantly observed
regardless of Na incorporation. For m≤0.90, [D, A]β became dominant for the films
without Na, while [D, A]α remained as the dominant emission for the films with Na.
A correlation between the prominence of [D, A]α and resistivities below 2×103 Ω· cm
was found, suggesting a reduced compensation by suppressed Se vacancy donors
due to the presence of Na.
Growth of Ultrathin Epitaxial 3C-SiC Films on Si(100) by Pulsed Supersonic Free Jets of CH3SiH3
Authors: Ikoma Yoshifumi , Endo Takao , Watanabe Fumiya , Motooka Teruaki
Published: October 2002

We have developed a new method for epitaxial growth of ultrathin (∼nm) 3C-SiC
films on Si(100) by pulsed supersonic free jets of methylsilane (CH3SiH3). It was found that
pit formation at the SiC/Si(100) interface was suppressed by increasing the pulse width and
the surface roughness was decreased by decreasing the number of CH3SiH3 jet pulses. A
linear relationship was observed between the film thickness and the pulse number in the thin
film region of less than ≈40 nm, while the growth rate was decreased and the thickness was
eventually saturated for further pulse irradiation.
Simulation for Thermal Processing of Amorphous Carbon Nitride
Authors: Lu Yong-Feng , He Zi-Feng , Ren Zhong-Min
Published: October 2002

A simulation model is established to study the amorphous structure of carbon nitride
under thermal processing. The method of our simulation involves the consideration of
material cohesive energy, which can determine the configuration of atoms in the matrix. The
thermal treatment of the material is considered as a Markov process with a transition
possibility determined by Gibbs distribution. Upon the simulated structure of amorphous
carbon nitride matrix, the bulk modulus of the material can be calculated. More detailed
study such as sp3/sp2 ratio of carbon and nitrogen vibration density spectra of the material
can be calculated by counting atoms with different type and vibration frequency. The
influence of an annealing process on the properties of amorphous carbon nitride has been
shown. According to our simulation, annealing can increase the number of sp2 hybridised
carbon atoms and lower the bulk modulus. The simulation method can provide a way to
study the novel material properties and the results can help experimentalists design their
synthesis process.
Optically Induced Rotation of Combined Mie Particles within an Evanescent Field of a Gaussian Beam
Authors: Song Young Gon , Chang Soo , Jo Jae Heung
Published: October 2002

We demonstrate a windmill type rotation of combined Mie particles caused by optical
forces of the evanescent field generated at the surface of a Gadolinium Gallium Garnet
prism where a linearly polarized Nd:YAG laser beam (of wavelength 532 nm and power
100 mW) is totally reflected. The combined particles such as doublets (or triplets)
consisting of polystyrene latex (or yeast) spheres with diameters of 3–5 µm are reported
to rotate with angular velocities of 1 rpm in water when the particles are slightly
displaced from the center of the Gaussian evanescent spot. The particle rotation in the
inhomogeneous evanescent fields can be useful for a potential application to micromotors
or microaccelerometers.
Optical Properties of Poly(2,5-dialkoxy-p-phenylenebutadiynylene)
Authors: Akihiko Fujii Akihiko Fujii , Takeshi Fujisawa Takeshi Fujisawa , Katsumi Yoshino Katsumi Yoshino , Masashi Kijima Masashi Kijima , Ikuo Kinoshita Ikuo Kinoshita , Hideki Shirakawa Hideki Shirakawa
Published: October 2002

Optical properties of poly(2,5-dialkoxy-p-phenylenebutadiynylene) (PDAPB), such as optical absorption, photoluminescence (PL) and electroluminescence (EL), have been studied. The electronic energy structures of PDAPB have been determined by optical and electrochemical measurements. Strong PL with high quantum efficiency has been observed in PDAPB, therefore, PDAPB can be considered as a candidate for use in EL materials. Intense EL has been demonstrated in PDAPB for the first time, in conducting polymers with two C-C triple bonds in a unit in the main chain. Anomalous temperature dependence in the absorption spectrum and PL have also been observed.
High-Quality InGaN Films Grown by Hot-Wall Epitaxy with Mixed (Ga+In) Source
Authors: Chu Shucheng , Saisho Tetsuhiro , Fujimura Kazuo , Sakakibara Shingo , Tanoue Fumiyasu , Ishino Kenei , Ishida Akihiro , Harima Hiroshi , Chen Yefan , Yao Takafumi , Fujiyasu Hiroshi
Published: October 2002

A simple mixed source (gallium and indium metals) method was used in a hot-wall epitaxial system to grow InGaN films on
sapphire with thick (∼1.5 µm) and thin (∼3 nm) GaN buffer layers. Indium incorporation was controlled independently by the
substrate temperature, the N2 partial pressure and the mixed source temperature. High-quality InGaN films were obtained,
showing strong near-band-edge emission peaks ranging from 370 to 465 nm and narrow X-ray rocking curve full-width at half
maximum for InGaN (0002) of 7.03 arcmin. Non-resonant Raman shift of InGaN layers was clearly observed for the first
time.
Sulfurization in Gas Mixture of H2S and O2 for Growth of CuInS2 Thin Films
Authors: Watanabe Takayuki , Nakazawa Hidenobu , Matsui Masahiro
Published: October 2002

We propose a new sulfurization process for the preparation of homogeneous CuInS2 films. The process was carried out
in a gas mixture of H2S and O2 with varying O2/H2S ratios, using an InS/Cu/Na2O2/In stacked layer
as the precursor. In this method, the decomposition of H2S is induced at low temperatures by O2 incorporation, thereby
promoting the sulfurization of the precursor. Consequently, the serious problem of In metal segregation, which deteriorates the
uniformity of CuInS2 films, is prevented. This method has realized the highest efficiency of Cu-poor CuInS2-based solar cells known to date.
Homoepitaxial (110) YBa2Cu3O7-δ/YBa2(Cu1-xFex)3O7-δ/YBa2Cu3O7-δ SNS Junctions
Authors: Usagawa Toshiyuki , Wen Jianguo , Koyama Satoshi , Utagawa Tadashi , Tanabe Keiichi
Published: October 2002

We report on the first successful single crystal SNS junction based on (110)
YBa2Cu3O7-δ (YBCO)/YBa2(Cu1-x
Fe
x
)3O7-δ (YBCFeO: 150 nm)/YBa2Cu3O7-δ
films grown on (110) YBCO single crystal substrates. The surface flatness is nearly
the same level as good as (110) YBCO homoepitaxial films, as confirmed by
Scanning Electron Microscopy, Reflection High Energy Electron Diffraction and
Transmission Electron Microscopy observations. The single crystal SNS junction
shows an anisotropic field dependence in large-junction behavior at 77 K. The field
supression of critical supercurrent I
c(T) is greater than 95% at 77 K and 9.0 K. The
temperature dependence of I
c(T) is well described by proximity SNS theory
near the junction transition temperature T
cn, but exibits nearly T-linear behavior
at low temperature.
On the Nonphotoactive Ionic Species for Thermal Fixing of Volume Holograms in Undoped Barium Titanate
Authors: Yasuo Tomita Yasuo Tomita
Published: October 2002

Polarization-dependent infrared absorption spectra in the
wavenumber range of 3200–10000 cm-1 have been measured in undoped barium
titanate to obtain theoretical estimates of the hydrogen ion concentration and
the activation energy of hydrogen ion migration. These values are
compared with the holographically determined ones for nonphotoactive and mobile ionic
species that fix (screen) the electronic hologram. The result
indicates that hydrogen ions are considered to be the most likely species
responsible for fixing volume holograms.
H2-related Defects in Si Quenched in H2 Gas Studied by Optical Absorption Measurements
Authors: Suezawa Masashi
Published: October 2002

Optical absorption spectra of Si annealed in H2 gas followed by quenching were studied.
Specimens were high-purity Si (dopant concentration; 4×1012 cm-3). They were sealed in quartz
capsules together with H2, annealed at high temperatures and quenched in water. Their optical
absorption spectra were measured by an FT-IR spectrometer at about 6 K. Six sharp optical
absorption peaks were observed at 3618.1, 2131.5, 2062.0, 1838.5, 817.6 and 776.2 cm-1. The
3618.1 and 1838.5 & 817.6 cm-1 peaks have been respectively assigned to be due to H2 and H2
*.
The activation (or formation) energies of H2 and H2
* were determined from the quenching
temperature dependence of the peak intensities. Those of H2 (3618 cm-1 peak) and H2
* (1838 cm-1
peak) were about 2.2 and 4.8 eV, respectively.
Low-Intensity Ultraviolet Photodetectors Based on AlGaN
Authors: Pernot Cyril , Hirano Akira , Iwaya Motoaki , Detchprohm Theeradetch , Amano Hiroshi , Akasaki Isamu
Published: October 2002

We report on the fabrication and the characterization of low-intensity ultraviolet (UV)
photodetectors based on Al
x
Ga1-x
N grown by organometallic vapor phase epitaxy, with threading
dislocation density in the range of 5–8×109 to 2×1011 cm-2 and 6–7×107 to 1×109 cm-2. The
detectors present dark current values below 100 fA at 10 V bias allowing a photocurrent to dark
current ratio greater than one even at 40 nW/cm2. The photodetectors fabricated on low-density
dislocation layers present a greatly reduced persistent photoconductivity. Also, they achieved a
rejection ratio of 3 orders of magnitude between UV and visible light with cutoffs at 365 and 270 nm
for x=0 and x=0.43, respectively.
GaAs/Ge/GaAs Sublattice Reversal Epitaxy on GaAs (100) and (111) Substrates for Nonlinear Optical Devices
Authors: Shinji Koh Shinji Koh , Takashi Kondo Takashi Kondo , Minoru Ebihara Minoru Ebihara , Tetsuya Ishiwada Tetsuya Ishiwada , Hidetaka Sawada Hidetaka Sawada , Hideki Ichinose Hideki Ichinose , Ichiro Shoji Ichiro Shoji , Ryoichi Ito Ryoichi Ito
Published: October 2002

Sublattice reversal epitaxy is demonstrated in lattice-matched
GaAs/Ge/GaAs (100) and (111) systems using molecular beam epitaxy, and confirmed
by reflection high energy electron diffraction and preferential etching.
In the GaAs/Ge/GaAs (100) system, the sublattice reversal is
assisted by self-annihilation of the antiphase domains generated at the
GaAs/Ge interface. In the GaAs/Ge/GaAs (111) system, the sublattice reversal
results from the unique structure of the As-terminated Ge (111) surfaces.
The quality of the sublattice-reversed GaAs crystal is investigated
using cross-sectional transmission electron microscopy. A method to
fabricate a periodically domain-inverted structure using sublattice reversal
epitaxy is demonstrated for the GaAs/Ge/GaAs (100) system.
Bulk Periodically Poled MgO-doped LiNbO3 by External Electric Field Application
Authors: Nakamura Masaru , Kotoh Masahiro , Taniguchi Hirokazu , Tadatomo Kazuyuki
Published: October 2002

Bulk periodically poled MgO-doped LiNbO3 (PPMgLN) crystals have
been successfully fabricated by an electric field poling process using a liquid
electrode technique. The fabricated PPMgLN crystals with a 30.0 µm
domain-inverted period were 0.5 mm thick and had uniform domain
structures more than 30 mm long. The ratio of the domain-inverted width
to the domain-inverted period (duty cycle) for fabricated PPMgLN was
approximately 50% on average. Furthermore, using the same method, 0.5-mm-thick
PPMgLN with a 17.6 µm domain-inverted period and more than
30 mm interaction length could be fabricated and the average duty cycle was
confirmed to be approximately 50%.
Laser-Diode-Pumped Microchip LiNdP 4O12 Lasers under Different Pump-Beam Focusing Conditions
Authors: Yusuke Asakawa Yusuke Asakawa , Ryoji Kawai Ryoji Kawai , Kazuyoshi Ohki Kazuyoshi Ohki , Kenju Otsuka Kenju Otsuka
Published: October 2002

Input-output characteristics and multimode oscillation properties have been investigated in laser-diode-pumped microchip LiNdP4O12 lasers under different pump-beam focusing conditions, using microscope objective lenses with varying magnifications. The lasing threshold and slope efficiency, as well as the number of oscillating modes, are shown to depend on the pump-beam radius. The results are explained in terms of the pump-radius-dependent thermal lens effect and the Auger recombination process in high-density pumping regimes.
Analysis of Decomposed Layer Appearing on the Surface of Barium Strontium Titanate
Authors: Fujisaki Yoshihisa , Shimamoto Yasuhiro , Matsui Yuichi
Published: October 2002

Chemical states and structures of thin degenerated layers grown on the surface of
(Ba, Sr)TiO3 (BST) films are investigated by X-ray photoelectron spectroscopy (XPS). It
was found that decomposition occurred as a result of the air exposure and also as a result of
annealing. A careful study of a Ba 3d peak in the XPS spectrum reveals that Ba in BST
crystal easily decomposes out of the perovskite phase and makes BaCO3 or barium oxides,
whereas no significant change occurs in Sr, or Ti oxides. This degenerated layer can be
removed by nitric acid treatment. It was also found that the surface BST becomes rather
stable against exposure to air compared with the original one after the nitric acid treatment.
High Resistant Phase-conjugated Stimulated Brillouin Scattering Mirror Using Fused-silica Glass for Nd:YAG Laser System
Authors: Yoshida Hidetsugu , Fujita Hisanori , Nakatsuka Masahiro , Yoshida Kunio
Published: October 2002

A fused-silica glass showed a high stimulated Brillouin scattering reflectivity excess of over 90% at an incident energy
of 200 mJ for a 18-ns pulse duration. It was found that the strong thermal lens effect in a Nd:YAG amplifier of focal length
less than 1 m was easily compensated by a phase-conjugating mirror based on stimulated Brillouin scattering of a fused-silica
glass. An output power of 7.2 W at 10 Hz could be delivered without changing the transversal beam profile. The lower absorption
and higher thermal shock parameter of the fused-silica will give the maximum operation level at over 3 kW of incident power with 90% reflectivity.
Energy-Dispersive Synchrotron Radiation Topographic Observation of InAs/GaAs Lattice-Mismatched Layer
Authors: Yoshifumi Suzuki Yoshifumi Suzuki , Yoshinori Chikaura Yoshinori Chikaura , Hideki Kii Hideki Kii , Masaaki Yoshida Masaaki Yoshida
Published: October 2002

Using white synchrotron radiation X-ray scattering spectrotopographic observation of InAs lattice-mismatched heteroepitaxial layer on GaAs substrate is described. Due to a considerable discrepancy between the lattice constants of InAs and GaAs, we took four topographs of the (002) and (004) InAs epitaxial layer, and of the (002) and (004) GaAs substrate, simultaneously. In order to discuss the defect contrast in detail, we made computer simulation of this experiment as a white beam topography using the Takagi-Taupin equations. Concerning the contrast from a local displacement from the matrix including a strain field, the behavior of white beam topographs is different from that of monochromatic ones.
Nucleation in the Nanometer Scale Selective Area Growth of II-VI Semiconductors
Authors: Adrian Avramescu Adrian Avramescu , Akio Ueta Akio Ueta , Katsuhiro Uesugi Katsuhiro Uesugi , Ikuo Suemune Ikuo Suemune
Published: October 2002

Nanometer-scale selective area growth of ZnS and ZnSe was investigated.
The growth was performed by metalorganic molecular-beam epitaxy (MOMBE) on a carbon-masked GaAs substrate at temperatures ranging from 350°C to 390°C.
For pattern sizes larger than several hundred of nanometers, a good selectivity and uniformity of the grown structures were observed, but for mask opening sizes less than ∼100 nm, uniformity of the grown structures was not satisfactory.
This situation was identified as originating from the poor nucleation and to be intrinsic to the nanometer-scale selective area growth.
In order to resolve this issue, the conditions for enhancing the nucleation were studied.
The replacement of conventional As–Zn bonding with Ga–S or Ga–Se bonding at the heterointerface proved to be effective for enhancing the nucleation probability, and thus, the uniformity of the grown nanostructures, while preserving good selectivity.
Estimation of the Minority Carrier Diffusion Length by Near-Field Photocurrent Measurement of p-n Junction in Silicon using Multiwavelength Excitation
Authors: Fukuda Hiroaki , Kadota Yasushi , Ohtsu Motoichi
Published: October 2002

Near-field photocurrent measurement is applied for the characterization of
p-n junction of silicon devices. By using a multiwavelength excitation source,
the penetration depth into the silicon substrate can be tuned from 10 nm to 685 nm. We have measured the minority carrier diffusion length from near-field
photocurrent signals. The minority carrier diffusion lengths of an electron L
n and a hole L
p are estimated as 0.47 and 0.37 µm.
Density of Ar Metastable Atoms on the Discharge Tube Wall Measured by Evanescent Laser Spectroscopy
Authors: Takeki Sakurai Takeki Sakurai , Tomoya Kubota Tomoya Kubota , Yuuichirou Takahara Yuuichirou Takahara , Yukio Inoue Yukio Inoue , Hirokazu Hori Hirokazu Hori
Published: October 2002

In order to measure the density of excited atoms in the metastable state on a discharge tube wall, evanescent wave spectroscopy is applied to a pure Ar
discharge. In the experiments, the evanescent laser wave interacts with the Ar metastable atoms. The detection of the evanescent-laser-induced fluorescence and the laser-induced evanescent-mode fluorescence indicates the existence of metastable atoms in
the vicinity of the wall within one wavelength of the laser. The absolute value of
density is obtained in comparison with the signal for
Rb atoms in the same system. The reflectance of metastable atoms at the wall
is also estimated.
Improvement of 1.5 µm Photoluminescence from Reactive Deposition Epitaxy (RDE) Grown β-FeSi 2 Balls in Si by High Temperature Annealing
Authors: Takashi Suemasu Takashi Suemasu , Yusuke Iikura Yusuke Iikura , Tetsuo Fujii Tetsuo Fujii , Ken'ichiro Takakura Ken'ichiro Takakura , Noriyoshi Hiroi Noriyoshi Hiroi , Fumio Hasegawa Fumio Hasegawa
Published: October 2002

We found that 900°C annealing was a very effective way to improve the 1.5 µm photoluminescence (PL) from β-FeSi2 balls with about 100 nm diameter grown by reactive deposition epitaxy (RDE) and embedded in Si crystals by molecular beam epitaxy (MBE).
The full-width at half maximum (FWHM) of the 1.5 µm PL peak was about 1/4 of that of the as-grown sample, after annealing at 900°C for 14 h. This was attributed to improvement of the β-FeSi2 quality. The FWHM of an X-ray diffraction β-FeSi2 (800) peak decreased from 0.24° to 0.14° by the annealing.
35 nm Metal Gate p-type Metal Oxide Semiconductor Field-Effect Transistor with PtSi Schottky Source/Drain on Separation by Implanted Oxygen Substrate
Authors: Wataru Saitoh Wataru Saitoh , Shigeharu Yamagami Shigeharu Yamagami , Atsushi Itoh Atsushi Itoh , Masahiro Asada Masahiro Asada
Published: October 2002

P-type metal oxide semiconductor
field-effect transistors with PtSi Schottky sources/drains
with a 35-nm long metal gate
were fabricated on a separation by implanted oxygen substrate by
electron-beam lithography and a self-aligned silicide process.
The drain current was -176 µA/µm and
the transconductance was 390 mS/mm
at V
DS = V
GS = -1.5 V.
For these devices, comparable drivability
to conventional metal oxide semiconductor
field-effect transistors was achieved.
The on/off ratio was improved using a very thin
silicon-on-insulator structure.
Nucleation Enhancement of Diamond via Electron Cyclotron Resonance Plasma
Authors: Sun Chao , Zhang Wenjun , Yang Jie , Lee Chun S. , Bello Igor , Lee Shui T.
Published: October 2002

A novel nucleation technique based on electron cyclotron resonance
microwave plasma was developed to grow diamond films. A nucleation density
higher than 108 nuclei/cm2 was achieved on an untreated, mirror-polished Si substrate.
Uniform diamond films were obtained by combining this nucleation method with
growth by the common microwave plasma chemical vapor deposition method.
Atomic force microscopy, Raman spectroscopy and scanning electron microscopy
were used to characterize the phase composition and morphology of the samples after
the nucleation and growth stages.
Molecular Weight Dependence of Dielectric Behavior of Polymer Electrolytes under Shear Flow
Authors: Shun-ichi Inoue Shun-ichi Inoue , Yasuyuki Kimura Yasuyuki Kimura , Kohzo Ito Kohzo Ito , Reinosuke Hayakawa Reinosuke Hayakawa
Published: October 2002

We have developed a new apparatus for measuring dielectric relaxation under
shear flow, and applied it to a typical polymer electrolyte system,
polypropylene oxide (PPO)-lithium perchloride,
while changing the molecular weight of PPO.
We observed a drastic increase in dielectric increment Δε
and a drastic decrease in conductivity σ
with increasing shear rate.
The molecular weight dependence of σ and the relaxation
time τ suggests that the conductivity is due to ion transport
assisted by the conformational change of the entire polymer chain
and the permittivity is ascribed to the ion fluctuation within a single
chain assisted by the segmental motion of a polymer.
On applying shear flow, the conformational change of a polymer chain is
strongly suppressed, which would cause the decrease in conductivity.
Anomaly of X-ray Diffraction Profile in Single-Walled Carbon Nanotubes
Authors: Maniwa Yutaka , Kumazawa Yoshinori , Saito Yumi , Tou Hideki , Kataura Hiromichi , Ishii Hiroyoshi , Suzuki Shinzou , Achiba Yohji , Fujiwara Akihiko , Suematsu Hiroyoshi
Published: October 2002

X-ray diffraction (XRD) studies on single-walled carbon nanotube (SWNT)
samples prepared by the arc-discharge method were reported. The XRD profile was
basically explained to be a result of triangular packing of SWNTs with a lattice
constant of 17.1 Å and an average nanotube radius of 7.1 Å. We found an
anomalous change in XRD profiles before and after heat-treatment of the SWNT
samples in air at ∼350°C. Combined with gravimetric measurements and resistivity
measurements, a detailed simulation of the XRD profiles showed that air (oxygen,
and/or nitrogen and/or water) can be condensed inside the SWNTs.
Micro-Textured Milky ZnO:Ga Thin Films Fabricated by Pulsed Laser Deposition Using Second-Harmonic-Generation of Nd:YAG Laser
Authors: Akio Suzuki Akio Suzuki , Tatsuhiko Matsushita Tatsuhiko Matsushita , Takanori Aoki Takanori Aoki , Yoshitaka Yoneyama Yoshitaka Yoneyama , Masahiro Okuda Masahiro Okuda
Published: October 2002

Approximately 800-nm-thick ZnO films doped with 4 wt% Ga2O3 (GZO films) have been deposited on glass and quartz substrates by a pulsed laser deposition method using Second-Harmonic-Genreation (SHG) of Nd:YAG laser (λ=532 nm). In all experiments, a repetition rate of 10 Hz, energy densities of 0.1–2.5 J/cm2, and irradiation times of 2–3 h were used. Scanning Electron Microscopy (SEM) observations of the film surface revealed that there were micro-textured structures (0.5–1 µm in diameter), surrounded by small rugged and irregular structures (250–400 nm in size). It was recognized from XRD spectra that a strong peak of (103) planes reflected from the micro-textured milky surfaces is dominant. A haze ratio of 46.6 % was obtained at a wavelength of 550 nm for approximately 800-nm-thick GZO (4 wt%) films grown at a substrate temperature of 300 °C in oxygen with a flow rate of 3 sccm. The lowest resistivity of 2.33×10-4 Ω·cm and the lowest sheet resistance of 2.72 Ω/sq were obtained for these GZO (4 wt%) films.
Nucleation and Faceting in Selectively Grown ZnS Pyramidal Dot Array for Short-Wavelength Light Emitters
Authors: Akio Ueta Akio Ueta , Adrian Avramescu Adrian Avramescu , Ikuo Suemune Ikuo Suemune , Hideaki Machida Hideaki Machida , Norio Shimoyama Norio Shimoyama
Published: October 2002

A ZnS dot array was selectively grown on (001) GaAs using metalorganic molecular-beam epitaxy.
The ZnS dot array has smooth facets and excellent uniformity.
To control the position of the active layer inside the dot structure which confines electrons and holes for small-sized light sources, the initial growth process for the dot structure was studied in detail.
It was found that delay time of growth initiation exists for small-area selective growth.
This delay was enhanced for smaller patterns.
The faceting of the grown structure, which determines the shape of the grown structure and controls the output power from the small dot light source as an optical cavity, was also discussed.
The faceting was critically dependent on the orientation of the mask opening.
The dot structures selectively grown in the patterns the sides of which are parallel to the [100] and [010] directions showed four smooth isotropic {034} related facets in the VI/II ratio from 0.5 to 3.
When the mask opening was aligned parallel to the [110] and [110] directions, the dot structures showed {113}A facets in the [110] direction and {110} and {113}B facets in the [110] direction.
These facets are anisotropic and change with the VI/II ratio.
Growth Mechanism of Surface Dots Self-Assembled on InP (311)B Substrate
Authors: Okada Takahiro Kawamura , Mitsuo Kawabe Mitsuo Kawabe
Published: October 2002

Self-assembled quantum dots (QDs) were fabricated on InP (311)B substrates
by only cleaning the substrate surface assisted by atomic hydrogen irradiation. The surface dots were studied by atomic force microscopy (AFM), photoluminescence (PL), and Auger analysis. The surface dots fabricated by only this cleaning process showed size uniformity and high-density features as good as those of In0.4Ga0.6As QDs reported on GaAs (311)B substrates. The PL and Auger measurements revealed that the composition of these surface dots was InAs
x
P1-x
(x > 0.5). We have also fabricated surface dots on InP (100) substrates by this cleaning method. The QDs were formed along the step edges and were lower in density than those on InP (311)B.
Improvement of YBa2Cu3Ox Single-Crystal Surface by Chemical Etching
Authors: Tanaka Nobue , Zama Hideaki , Morishita Tadataka , Yamamoto Hiroshi
Published: October 2002

The single-crystal YBa2Cu3O
x
(YBCO) surface presents precipitates that aggregate to form a
very thin damaged layer on the surface after mechanical polishing and thermal annealing. The
damaged layer was removed by dipping it into a chemical etchant, HCl/methanol. After applying
the etching process, YBCO(001) surfaces exhibited a well-defined step-and-terrace feature with
unit-cell step height. No precipitates were observed from the etched substrates after annealing.
Homoepitaxial films on etched substrates grew with unit-cell-high steps and step-edge facets,
while those on as-polished substrates exhibited a grain structure with rough edges.
Formation of Boron Nitride (BN) Fullerene-Like Nanoparticles and (BN)xCy Nanotubes Using Carbon Nanotubes as Templates
Authors: Han Weiqiang , Bando Yoshio , Kurashima Keiji , Sato Tadao
Published: October 2002

A method for the synthesis of boron nitride (BN) fullerene-like nanoparticles (FNPs) and
(BN)
x
C
y
nanotubes in large quantities using carbon nanotubes as templates is presented.
Boron oxide vapor was reacted with nitrogen gas in the presence of carbon nanotubes
(CNTs) at 1573 K in a boron nitride crucible to form BN-FNPs and BN-C nanotubes. FNPs
usually display a clear polyhedral morphology with an inner hollow space. The shell thickness
and inner empty spaces of these FNPs typically range from 2–8 nm and 5–25 nm, respectively.
The (BN)
x
C
y
nanotubes have diameters and lengths similar to the starting CNTs, but have
much more ordered structures. The growth mechanism is discussed.