bluuebunny/crossref_metadata_2025 huggingface dataset:
Microphase Separation in Dehydrated N-isopropylacrylamide/sodium Acrylate Gel
Authors: Masaaki Sugiyama Masaaki Sugiyama , Shuichiro Kuwajima Shuichiro Kuwajima , Yuji Soejima Yuji Soejima , Atsushi Nakamura Atsushi Nakamura , Nobuyasu Hiramatsu Nobuyasu Hiramatsu , Takashi Kikukawa Takashi Kikukawa , Atsushi Suzuki Atsushi Suzuki , Kazuhiro Hara Kazuhiro Hara
Published: October 2002

The first small-angle X-ray scattering (SAXS) measurements were carried out
in order to examine the mesoscopic structure in the
N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel.
By the SAXS measurements, a prominent peak was found in the
dehydrated gel around 0.026 Å-1.
Taking into account of the cross section magnitude against X-ray,
the concentration fluctuation of Na+ ions was a probable candidate for
making contrast for the SAXS profile, which depends on the distribution of
the hydrophilic group.
Therefore, it was concluded that the mesoscopic structure found in the present
study is due to the hydrophilic domains in the dehydrated gel which capture
the Na+ ions and the remnant water inside the gel.
Multivacancy and Its Hydrogen Decoration in Crystalline Si
Authors: Toru Akiyama Toru Akiyama , Yasuharu Okamoto Yasuharu Okamoto , Mineo Saito Mineo Saito , Atsushi Oshiyama Atsushi Oshiyama
Published: October 2002

We present first-principles total-energy calculations that reveal
microscopic structures of multivacancies in Si and their feasibility
of hydrogen incorporation. We find that the hexavacancy V
6 and the
decavacancy V
10 are stable, and that the stable
multivacancies are either free from or fully decorated with hydrogen
depending on its chemical potential. We also find that the H-decorated
multivacancy is capable of containing an additional H2 molecule
and hereby exhibits peculiar vibration spectra related to the
hydrogen.
The Combined Effects of Nitrogen Implantation at S/D Extension and N2O Oxide on 0.18 µm N- and P-Metal Oxide Field Effect Transistors (MOSFETs)
Authors: Chao Tien-Sheng , Chang Sun-Jay , Chien Chao-Hsin , Lin Horng-Chih , Huang Tiao-Yuan , Chang Chun-Yen
Published: October 2002

The combined effects of N2-implantation at S/D extension and N2O oxide on
0.18 µm n- and p-Metal oxide field effect transistors (MOSFETs) were investigated. It is found that for n-channel
transistors, V
th roll-off and drain-induced barrier lowering (DIBL) are enhanced by
nitrogen incorporation through either N2O oxide or N2-implantation. However, for p-channel transistors, opposite trends are observed for N2O oxide and N2-implantation.
Finally, nitrogen incorporation by either method is found to improve the interface
quality for nMOSFETs. While for p-channel transistors, best results are obtained by
the combined effects of N2O oxide and N2-implantation.
Temperature-Dependent Characteristics of the Inverted Delta-Doped V-Shaped InGaP/InxGa1-xAs/GaAs Pseudomorphic Transistors
Authors: Chang Wen-Lung , Pan Hsi-Jen , Wang Wei-Chou , Thei Kong-Beng , Cheng Shiou-Ying , Lour Wen-Shiung , Liu Wen-Chau
Published: October 2002

The temperature-dependent characteristics of InGaP/In
x
Ga1-x
As/GaAs
pseudomorphic transistors with an inverted delta-doped V-shaped channel have
been studied. Due to the presented wide-gap InGaP Schottky layer and the
V-shaped channel structure, the degradation of device performance with
increasing the temperature is not so significant. Experimentally, for a
1×100 µm2 device, the gate-drain voltages at a gate leakage current of
260 µA/mm and the maximum transconductances g
m,max are 30 (22.2) V and
201 (169) mS/mm at the temperature of 300 K (450 K), respectively. Meanwhile, the broad
and flat drain current operation regimes for high g
m, f
T, and f
max
are
obtained.
Electron-Stimulated Desorption of a Br-Chemisorbed Si(111)-7 ×7 Surface by Using a Scanning Tunneling Microscope
Authors: Mochiji Kozo , Ichikawa Masakazu
Published: October 2002

Atomic structural changes of Br-chemisorbed Si(111) surfaces under
electron-stimulated desorption have been investigated by using field-emitted
electrons from the tip of a scanning tunneling microscope. Irradiating these
surfaces with 30-eV electrons induces various desorptions depending on the initial
Br coverage. At low coverage, only Br atoms desorb, and no atomical changes
occur on the Si surface. At saturation coverage, Si adatom desorption becomes
remarkable but Br atoms more predominantly desorb from the adatom layer. After
the irradiation, a novel structure consisting of four Si atoms appears around the
dimer position in a 7×7 unit cell. This structure is evidence that the positions of the
adatoms are shifted by multiple brominations and these Br atoms are preferentially
removed by electron-stimulated desorption.
Proposal of an Alternative Technique for High Density Data Storage
Authors: Yihong Wu Yihong Wu , Towchong Chong Towchong Chong
Published: October 2002

An alternative technique is proposed and discussed for ultra-high
areal density data storage. The proposed data storage system consists of a
ferroelectric medium and the corresponding writer and reader for writing the
data to and reading the data from the disk medium. Comparing to the
existing magnetic data storage systems, the new recording system features
simplicity in writer design and fabrication and a large output signal from
the read sensor. The adoption of a perpendicular recording scheme also makes
it more promising for future high-density recording applications. Its other
advantages and drawbacks are also discussed based on an preliminary analysis
on the writing and reading processes.
Photonic Crystal Using Anodic Porous Alumina
Authors: Masuda Hideki , Ohya Masayuki , Asoh Hidetaka , Nakao Masashi , Nohtomi Masaya , Tamamura Toshiaki
Published: October 2002

Two-dimensional (2D) photonic crystals in the visible wavelength region were
fabricated using anodic porous alumina with a highly ordered hole array configuration.
The transmission properties of an ordered triangular array of an air cylinders with high
aspect ratio in alumina matrix showed a stop band in the spectrum which corresponds
to the band gap in the 2D photonic crystals.
Spatial Phase Information Transmission through Single-Mode Fibers by Coherence Function Shaping of Low Coherent Light
Authors: Yuichi Teramura Yuichi Teramura , Atsushi Shirakawa Atsushi Shirakawa , Fumihiko Kannari Fumihiko Kannari
Published: October 2002

We experimentally demonstrated transmission of spatial phase information recorded in a spatial-light modulator through a single-mode optical fiber using a coherence function shaper and spectral holography with a low coherent light source. A replica of the diffraction pattern of the original kinoform is generated from a spectral hologram when the hologram is read with HeNe lasers. In contrast to a similar coherent imaging technique with ultrashort pulses, the low coherent light suffers less from nonlinear phase modulation because of its low intensity.
Thermal Cracking Effects of CeCl3 Dopant on Blue Electroluminescent Properties in SrGa2S4:Ce Thin Films
Authors: Tanaka Katsu , Okamoto Shinji , Izumi Yoshitaka , Inoue Yoji , Kobayashi Kikuo
Published: October 2002

The thermal cracking effects of CeCl3 dopant on the blue
electroluminescent (EL) properties in SrGa2S4:Ce thin films
grown by molecular beam epitaxy (MBE) system were
investigated. The cracking enhanced the Ce3+ ion density in
SrGa2S4:Ce film without degrading the crystallinity. The
maximum EL luminance was thereby increased to 85 cd/m2 at a
driving frequency of 1 kHz. The chromaticity of the EL was also
maintained in the pure blue region.
Anomaly in Rotational Diffusion of Photophysical Probe Near Volume Phase Transition of Copoly(Acrylamide-Acrylic Acid) Gels: Steady State and Time-Resolved Fluorescence Study
Authors: Masahiko Annaka Masahiko Annaka , Hiroyuki Takagi Hiroyuki Takagi , Takayuki Nakahira Takayuki Nakahira
Published: October 2002

Changes in the microenvironment of pyrene-labeled copoly(acrylamide-acrylic acid) gels are investigated by means of fluorescence spectroscopy. An anomaly in the microscopic motion of a pyrenyl probe was observed in the vicinity of the phase transition: the average lifetime of monomer emission approached zero, and the rotational diffusion constant of pyrenyl probe became infinite. Density fluctuation and the nonequilibrium situation near the phase transition are considered to cause the rapid microscopic fluctuation of the network and solvent molecule.
n-Type Control by Sulfur Ion Implantation in Homoepitaxial Diamond Films Grown by Chemical Vapor Deposition
Authors: Hasegawa Masataka , Takeuchi Daisuke , Yamanaka Sadanori , Ogura Masahiko , Watanabe Hideyuki , Kobayashi Naoto , Okushi Hideyo , Kajimura Koji
Published: October 2002

n-type control was achieved by sulfur-ion-implantation in
homoepitaxial diamond (100) films grown by chemical vapor deposition
(CVD) for the first time. Sulfur-implantation was carried out with
energies of up to 400 keV at 400°C. The activation energy of the
conductivity was 0.19–0.33 eV depending on the conditions of ion
implantation. A junction between this layer and a boron-doped p-type
layer was fabricated by combining sulfur-implantation with gas-phase
boron doping during CVD. The junction exhibited clear pn junction
properties. The capacitance of the junction decreased with reverse
bias voltage, which confirms that the depletion region of the junction
was actually extended with the reverse bias voltage.
Novel High-Q Solenoidal Inductor Using Bondwires for GaAs Monolithic Microwave Integrated Circuits (MMICs)
Authors: Lee Hai-Young , Lee Yong-Goo , Kim Sung-Jin , Yun Sang-Ki
Published: October 2002

A novel high quality(Q)-factor integrated inductor using bondwires is fabricated on a
semi-insulating GaAs substrate for high performance GaAs monolithic microwave integrated circuits (MMIC). The solenoidal
inductor of vertical bondwires shows significant improvements of the Q-factor (38–63)
and the resonant frequency (9.4–17 GHz) by virtues of the very low series resistance and
parasitic capacitance.
Fabrication of YBa 2Cu 3O 7 Step-Edge Junctions on Sapphire Substrates
Authors: Ho Kim In-Seon Kim , Ki Park Yong
Published: October 2002

YBa2Cu3O7 step-edge Josephson junctions have been
fabricated on sapphire substrates with a CeO2 buffer layer. The
steps were formed by the Ar-ion milling technique having step angles
in a wide range (α= 20° to 70°). The
current-voltage curves of the junctions formed on low-angle
(<50°) steps exhibit RSJ-like behaviors at 77 K. The critical
current (I

C
) decreased and normal resistance (R

N
)
increased with increasing step angle (α) in the range
20° < α< 50°. A large I

C

R

N

value of 250 µV with junction resistance R

N
≈5 Ω and critical current
I

C
≈50 µA at 77 K
could be obtained reproducibly with 5 µm microbridges formed on
35° steps. The temperature dependence of the critical current
and the normal resistance suggest the presence of a metallic barrier
as the interface layer in a SNS-type junction.
Morphology of (YxGd1-x)BO3:Eu Phosphor Particles Prepared by Spray Pyrolysis from Aqueous and Colloidal Solutions
Authors: Kang Yun Chan , Park Seung Bin
Published: October 2002

(Y
x
Gd1-x
)BO3:Eu phosphor particles were prepared by the spray pyrolysis. The effect of preparation
conditions such as Y/Gd ratio, preparation temperature, boric acid concentration used as boron source,
post-treatment temperature, and doping concentration of Eu, on the crystallinity, morphology, and
luminescence characteristics of particles were investigated. To control the morphology of particles,
colloidal solution obtained by aqueous solution method was introduced in the spray pyrolysis. The borate
particles prepared by the spray pyrolysis from the aqueous solution had low thermal stability because of
low melting point of boron component and hollowness of as-prepared particles. The as-prepared particles
prepared from the colloidal solutions had higher thermal stability than that of particles prepared from the
aqueous solution. The maximum photoluminescence intensity of particles prepared from the colloidal
solution was 145% of that of particles prepared from the aqueous solution.
Characterization of Sputtered TiNi Shape Memory Alloy Thin Films
Authors: Surbled Patrick , Clerc Catherine , Pioufle Bruno Le , Fujita Hiroyuki
Published: October 2002

The sputtering of TiNi polycrystalline alloys without and with a
titanium mesh has been investigated for the development of shape
memory alloy (SMA) micro-actuators. The thickness and composition
distributions of TiNi thin films have been determined by Rutherford
backscattering spectroscopy (RBS). The composition of sputtered films
was demonstrated to depend on the density of the titanium mesh and the
distance from the target center, thus enabling easy fabrication of
high and low temperature SMA actuators. The transition temperatures
and resistivity have been measured with respect to the composition.
Sharp Red Organic Light-Emitting Devices with Enhanced Efficiency
Authors: Jabbour Ghassan E. , Wang Jia-Fu , Kippelen Bernard , Peyghambarian Nasser
Published: October 2002

The fabrication of efficient and bright red light-emitting organic electroluminescent devices based
on Eu-complex, having narrow spectral width, is achieved by enhancing the electron injection process
through the use of LiF/Mg cathode. Devices with external quantum efficiency exceeding 1% and light
output higher than 320 cd/m2 are presented. While the external quantum efficiency at 100 cd/m2 is
comparable, the luminous efficiency is 2.6 times higher than that of the recent state-of-the-art devices
based on the phosphorescent dye PtOEP.
A Two-Dimensional Photonic Crystal Laser
Authors: W. Haus Kuon Inoue
Published: October 2002

We report on observation of laser action unique to a two-dimensional (2D) photonic lattice.
When dye-solution filled in air-holes of a 2D lattice was optically-pumped, laser action without
external mirrors is found to occur at a specific wavelength corresponding to a flat band-dispersion
in a high-symmetry direction of the 2D lattice plane; a small group-velocity is responsible for the
lasing. On further increasing the pump-fluence, another laser action is also found to occur around
a peak wavelength of the spontaneous emission spectrum. This lasing is interpreted of as arising
from the so-called uncoupled modes possessing a high Q-value.
Effect of RF Plasma Etching on Surface Damage in CsLiB6O10 Crystal
Authors: Kamimura Tomosumi , Yoshimura Masashi , Mori Yusuke , Sasaki Takatomo , Yoshida Kunio
Published: October 2002

The laser-damage resistance of the CsLiB6O10 (CLBO) surface for UV generation was successfully improved after removing the
polishing compound by rf plasma etching. The ZrO2 used as CLBO polish was found to be embedded in the crystal surface to a depth of
60 nm. We could remove the polishing compound without degradation of the surface condition when the applied rf power was less than 100 W. For the ∼7 W fourth-harmonic generation
(266 nm) of a Nd:YAG laser (100 Hz), the surface lifetime of a 4HG crystal could be increased more than 10 times compared with that of an
as-polished surface. No surface damage was observed over 160 h of operation.
Low Temperature Chemical Vapor Deposition of (Ba, Sr)TiO3 Thin Films for High Density Dynamic Random Access Memory Capacitors
Authors: Joo Jae-Hyun , Park Jong-Bum , Kim Younsoo , Lee Kong-Soo , Lee Jun-Sik , Roh Jae-Sung , Kim Jae-Jeong
Published: October 2002

(Ba, Sr)TiO3 (BST) films are deposited on 8-inch wafers by the metal organic chemical vapor deposition
(MOCVD) technique at a temperature as low as 400°C to obtain conformal step coverage and prevent
oxidation of the diffusion barrier of simple stacked capacitors. The problems of low temperature process
(formation of protrusions, titanium deficiency, severe thickness deviation) could be successfully
overcome by proper modification of the CVD system and process conditions. Retrofitting the vaporizer to
obtain flash evaporation of the liquid chemical source and introducing N2O gas as an oxidant were highly
effective for reducing the thickness deviation and titanium deficiency. The Pt/BST/Pt capacitor with BST
films deposited at 400°C and post-annealed at 700°C for 30 min under nitrogen ambient shows excellent
electrical properties (T
o
x∼6.6 Å, J∼1×10-7 A/cm2 @±1 V), which are satisfactory for application to high
density dynamic random access memory (DRAM) capacitors beyond 256 Mbit generation.
Self-Limiting Growth of Specular InP Layer by Alternate Injection of Triethylindium and Tertiarybutylphosphine in Ultrahigh Vacuum
Authors: Otsuka Nobuyuki , Nishizawa Jun-ichi , Kikuchi Hideyuki , Oyama Yutaka
Published: October 2002

Alternate injection of triethylindium (TEI) and tertiarybutylphosphine without precracking
has been studied to realize low-temperature growth of an InP layer on an (001) InP substrate
in ultrahigh vacuum (UHV). Self-limiting growth, in which the growth rate is independent of
the injection time and the injection pressure of the sources, was demonstrated at a temperature
as low as 320°C. The self-limiting growth with a growth rate of around 0.75 monolayer per
cycle and specular surface morphology was achieved. A clean regrown interface is expected
by combining with the digital etching achieved at low temperature in UHV. The
decomposition mechanism of TEI on InP surface is discussed.
Photoluminescence Dynamics of Aluminumquinoline/Oxadiazole Multilayer Structures
Authors: Tadahiro Nakazawa Tadahiro Nakazawa , Mitsuru Asano Mitsuru Asano , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: October 2002

Photoluminescence (PL) dynamics of aluminumquinoline/oxadiazole
(Alq3/PBD) multilayer structures,
which may possess a carrier confinement type-I energy lineup,
has been investigated by time-resolved PL spectroscopy
with a mode-locked Ti-sapphire laser. The decay time of the emission from PBD in the multilayer structure
was as fast as several picoseconds, in contrast to that from a PBD single layer, 1.7 ns,
and tended to increase with an increase in PBD thickness.
For the emission from Alq3, on the other hand,
only a slight increase in the decay time was observed
in the multilayer structure compared to a single layer.
These results indicate the rapid energy transfer from PBD to Alq3,
similar to that in semiconductor quantum well structures
with the type-I energy lineup.
Violet InGaN/GaN/AlGaN-Based Laser Diodes Operable at 50°C with a Fundamental Transverse Mode
Authors: Nakamura Shuji , Senoh Masayuki , Nagahama Shin-ichi , Matsushita Toshio , Kiyoku Hiroyuki , Sugimoto Yasunobu , Kozaki Tokuya , Umemoto Hitoshi , Sano Masahiko , Mukai Takashi
Published: October 2002

A violet InGaN multi-quantum-well (MQW)/GaN/AlGaN separate-confinement-heterostructure
laser diode (LD) was grown on epitaxially laterally overgrown GaN on sapphire.
The threshold current density was 3.9 kA/cm2. The LDs with cleaved mirror facets showed an
output power as high as 30 mW under room-temperature continuous-wave (CW) operation.
The stable fundamental transverse mode in the near-field patterns was observed at an output
power up to 30 mW. The lifetime of the LDs at a constant output power of 5 mW was more
than 1,000 h under CW operation at an ambient temperature of 50°C. The estimated lifetime
was approximately 3,000 h under these high-power and high-temperature operating conditions.
Nuclear Magnetic Resonance of 7Li in LiBO2 Crystal
Authors: Matsuo Toru , Shibasaki Masayuki , Katsumata Tooru
Published: October 2002

The 7Li NMR spectra and spin lattice relaxation rates in
crystalline LiBO2 sample were measured. The spectra exhibit a broad
single line at low temperature and start to show a new narrow peak at
the expense of the original peak as the temperature increases, i.e.,
in addition to a broad line, a narrow line is observed to grow as the
temperature increases.
Time-Resolved X-ray Shadowgraphy Experiment of Laser Ablation of Aluminum using Laser-Induced Picosecond Pulsed X-rays
Authors: Hironaka Yoichiro , Inoue Tomoharu , Fujimoto Yasushi , Nakamura Kazutaka G. , Kondo Ken-ichi , Yoshida Masatake
Published: October 2002

We have developed an experimental setup for picosecond time-resolved X-ray
shadowgraphy and applied it to observe laser ablation. X-rays are generated by
femtosecond laser focusing on a tungsten target. The pulse duration of the generated
X-rays is measured to be 33 ps. Using an optical delay system, a series of time-resolved shadowgraphs of a plasma plume, which is generated by laser ablation using
300 ps laser beam irradiation on an aluminum target, are clearly obtained by a single
laser shot exposure.
Doping Effects on P-type InGaAs/AlGaAs Quantum Well Structures for Infrared Photodetectors Grown by Molecular Beam Epitaxy
Authors: Zhang Dao Hua , Shi Wei , Zhang Peng Hua , Yoon Soon Fatt
Published: October 2002

We report the effects of Be concentration incorporated into the well material on the p-type
InGaAs/AlGaAs multiple quantum well structures. The increased Be doping is found to cause red
shift of the dopant-related and excitonic luminescence in the wells of the structures, increase well
width, deteriorate the interface quality and increase lattice mismatch. Those factors affect the
positioning of the heavy and light holes in the valence band well, and thus the absorption
wavelength resulted from the intersubband transition. These observations are useful for the design
of p-type quantum well infrared photodetectors.
Metal Particulate (MP)/Metal Evaporation (ME) Double-Layered Media for High-Density Recording
Authors: Endo Katsumi , Yoshida Osamu , Sasaki Kenji , Nakayama Kazuhiko , Maki Kazuo
Published: October 2002

We have fabricated a double-layered tape composed of a metal thin film
underlayer and a metal particulate (MP) upper layer. Two kinds of metal
thin films–Cu nonmagnetic and Co magnetic–were deposited under the MP
layer by metal evaporation (ME). We found that the magnetic underlayer
affected the magnetic recording properties of the tape in high-density
recording. Co magnetic underlayer tape output was significantly enhanced
compared to Cu nonmagnetic underlayer tape output, especially at shorter
recording wavelengths. It is possible to enhance output by introducing
another high-density recording layer under the main magnetic layer. We
consider that the internal magnetization of the magnetic underlayer assists
the upper layer recording under this condition, providing a new way to
improve the recording density of MP media.
Optical Image Storage Based on All-Optical Poling in Polymer Films
Authors: Si Jinhai , Kitaoka Kenji , Mitsuyu Tsuneo , Hirao Kazuyuki
Published: October 2002

Optical image storage was investigated by an all-optical poling method in thermal-crosslinked azo-polyurethane films. During the
writing process, samples were irradiated simultaneously by the coherent superposition of the 1064-nm fundamental and the 532-nm
second-harmonic light of a nanosecond-pulsed Nd:YAG laser. This optical image storage provides a micropatterning of the second-order
susceptibility for polymer films, which can transfer an infrared reading beam into a visible signal for optical processing.
Al2O3/InP Structure with Less Oxides of InP Fabricated by Helicon-Wave Exicited O2–Ar Plasma Treatment of Al/InP
Authors: Tomoyuki Motegi Tomoyuki Motegi , Junji Tomita Junji Tomita , Hideaki Ikoma Hideaki Ikoma
Published: October 2002

Al2O3/n-InP (100) structure was fabricated by helicon-wave excited O2–Ar plasma treatment of an Al/InP substrate. The capacitance-voltage (C–V) and conductance-voltage (G–V) characteristics were measured to evaluate the electrical quality of the Al2O3/InP interface. X-ray photoelectron spectroscopic (XPS) measurements were performed to investigate the chemical composition and depth profile. Reasonably good C–V characteristics were obtained when the flow-rate ratios of Ar were 30% and 40%. XPS data indicated that Al2O3 was uniformly formed along the whole film thickness. Oxides of In (In2O3) and InP (InPO3, In(PO3)3 and InPO4) were scarcely observed in the film and at the interface with the InP substrate, probably due to the reductioning effect of Al. The absence of the oxides is one of the reasons for the reasonably good C–V characteristics.
Effect of Ion Irradiation on Coherent Phonon Dynamics in Bismuth
Authors: G. Nakamura Kunie Ishioka , Shun-ichi Hishita Shun-ichi Hishita , Masahiro Kitajima Masahiro Kitajima
Published: October 2002

We investigate the effects of crystalline disorder on the dynamics of coherent optical phonons in bismuth using optical heterodyne detection (OHD). The excitation and relaxation of A1g
coherent phonons are studied with femtosecond time resolution for a bismuth single crystal, as-deposited microcrystalline film, and ion-irradiated microcrystalline film. The relaxation time of the coherent phonon in bismuth decreases with increasing disorder, from 4.75 ps for the single crystal to 2.16 ps for the ion-irradiated microcrystalline film. The decrease in relaxation time is attributed to the dampening of phonons due to grain boundaries and point defects, and correlates with the spatial localization of phonons.
Macroparticle-Free Ti–Al Films by Newly Developed Coaxial Vacuum Arc Deposition
Authors: Chun Sung-Yong , Chayahara Akiyoshi , Kinomura Atsushi , Tsubouchi Nobuteru , Heck Claire , Horino Yuji , Fukui Hirotaka
Published: October 2002

Titanium aluminide thin films are deposited on glassy carbon substrates by the coaxial vacuum arc deposition process.
A rod-shaped Ti–Al alloy is employed as the evaporation source. In our vacuum arc system, because the spatial position of
plasma on the surface of the evaporation source can be controlled by pulsed arc discharge, the thickness of the Ti–Al film
can be controlled at nanometer scale. Amorphous stoichiometric Ti–Al films are synthesized from one Ti–Al alloy target at
room temperature by changing the number of pulses of the arc discharge. Multilayered Ti and Al films could also be fabricated
by changing the target and the number of pulsed arc discharges.
Continuous Wave Operation at Room Temperature of InGaN Laser Diodes Fabricated on 4H-SiC Substrates
Authors: Kuramata Akito , Kubota Shin-ichi , Soejima Reiko , Domen Kay , Horino Kazuhiko , Hacke Peter , Tanahashi Toshiyuki
Published: October 2002

We demonstrated continuous wave operation at room temperature of InGaN laser
diodes fabricated on 4H-SiC substrates. The threshold current and voltage were 60 mA
and 8.3 V, respectively. The threshold current corresponds to a threshold current
density of 4 kA/cm2. No difference in the threshold current or voltage was observed
between 4H-SiC and 6H-SiC substrates. The laser oscillation was observed up to 80°C
for CW operation. The peak lasing wavelength was 404.4 nm. The lifetime was 57 hours
under automatic power controlled conditions with a constant output power of 1 mW at 25°C.
Strain Modification of GaN in AlGaN/GaN Epitaxial Films
Authors: Steude Guido , Meyer Bruno K. , Göldner Axel , Hoffmann Axel , Kaschner Axel , Bechstedt Friedhelm , Amano Hiroshi , Akasaki Isamu
Published: October 2002

We investigated AlGaN/GaN heterostructures grown by metal-organic vapor-phase
epitaxy on sapphire by calorimetric absorption, transmission and reflection spectroscopy
(CAS/CTS/CRS) at 47 mK. The AlGaN film on a 2-µm-thick GaN layer introduces additional
compressive strain into the GaN layer. A blue shift of the A- and B-exciton line positions is
directly proportional to the AlN molar fraction in the films. The amount of strain in the GaN
layers is quantified by micro-Raman experiments. We can explain the results by taking into
account the elastic properties of GaN and AlGaN.
Windowless High-Tc Superconducting Quantum Interference Device Microscope
Authors: Tanaka Saburo , Yamazaki Osamu , Shimizu Ryoji , Saito Yusuke
Published: October 2002

A high-T
c superconducting quantum interference device (SQUID) microscope with a sample chamber isolated by a
shutter gate was designed and constructed for imaging samples at both room temperature and 77 K. According to our scheme, the
separation of the sample from the SQUID can be less than several micrometers, in principle. We have successfully imaged a trapped
flux in a YBa2Cu3O7-y
thin-film ring at 77 K.
2.5 Gb/s Electroabsorption Modulator Integrated with Partially Gain-Coupled Distributed Feedback Laser Fabricated Using a Very Simple Device Structure
Authors: Luo Yi , Wen Guo-Peng , Sun Chang-Zheng , Li Tong-Ning , Yang Xin-Min , Wu You-Sheng , Wang Ren-Fan , Wang Cai-Ling , Huang Tao , Jin Jin-Yan
Published: October 2002

An electroabsorption (EA) modulator integrated with a partially gain-coupled distributed
feedback (DFB) semiconductor laser is fabricated using a very simple device structure. An
identical epitaxtial layer is used for the active layer of the laser and the waveguide of the
modulator to achieve wavelength compatibility between the two components. The fabricated
device shows a low threshold current of 27 mA, a large extinction ratio of over 17 dB at -3 V,
and a fiber coupled power of 2.7 mW. Packaged modules are also fabricated for 2.5 Gb/s
operation. The power penalty at a 10-10 bit-error rate is less than 0.5 dB after transmission
through 240 km of traditional fiber. The influence of lasing wavelength detuning on device
performance is also discussed based on our experimental data.
Growth of Al2O3/Y3Al5O12 Eutectic Fiber by Micro-Pulling-Down Method and Its High-Temperature Strength and Thermal Stability
Authors: Yoshikawa Akira , Epelbaum Boris M. , Fukuda Tsuguo , Suzuki Kenji , Waku Yoshiharu
Published: October 2002

Fiber growth of Y3Al5O12 (YAG) matrix composite reinforced with the sapphire phase was investigated to manufacture sapphire/YAG eutectic composites using the micro-pulling-down (µ-PD) method. Both the sapphire and YAG phases were crystalline. We have controlled the fiber diameter from 200 µm to 2 mm. The maximal length was about 500 mm. The eutectic fibers have superior
high-temperature strength properties, 580 MPa at 1500°C. In the tensile test at this temperature, the fiber showed considerable (about 10%) plastic deformation due to dislocation motion. The microstructure of this eutectic fiber has a very high thermal stability.
No grain growth was observed after even 75 h of heat treatment at 1500°C in air atmosphere.
Dielectric Polarization Noise in Low-Noise Si Junction Field-Effect Transistors at 77 K
Authors: Akiba Makoto
Published: October 2002

The dielectric polarization noise in low-noise silicon junction field effect transistors (Si JFETs) was
measured at 77 K and at low frequencies. The noise generated in the p-n junction was consistent with
that of previous measurements. A noise larger than or comparable to the amount of noise in the p-n
junction was found at the lead connected to the gate and at the gate electrode. All of the power spectra
of the noise current were proportional to the frequency. Reduction of the dielectric polarization noise
is important for ultra low-noise current measurement.
Elimination of Dynamic Instabilities in the +c-face Incident Photorefractive BaTiO3 Mutually Pumped Phase Conjugator
Authors: Chang Chi Ching , Chen Tzu Chiang , Tang Li Chuan , Yau Hon Fai
Published: October 2002

Experimental observations of the dynamic instabilities in the +c-face incident
mutually pumped phase conjugator (MPPC) of a BaTiO3 crystal are reported for
the first time. Experiments show that it is possible to stabilize the phase-conjugate
output by choosing a proper geometry formed from the crystal and two
incident beams. By choosing the proper geometry the essential configuration
of the MPPC attained is a “kite” rather than a “fish head”. Data also indicate
that the phase-conjugate output can reach a very steady state with a high value
(∼32%) and is insensitive to angular and positional variations.
Phase and Microstructure Analysis of Lead Germanate Thin Film Deposited by Metalorganic Chemical Vapor Deposition
Authors: Zhang Fengyan , Li Tingkai , Tweet Douglas J. , Hsu Sheng Teng
Published: October 2002

Lead Germanate thin films have been successfully deposited on different electrodes by a
metalorganic chemical vapor deposition (MOCVD) system for the first time. Three
different phases have been characterized. The single c-axis oriented Pb5Ge3O11 phase has
been deposited on Ir, Ir/Pt (Pt on top) and Pt electrodes respectively and shows a very
uniform surface. A lead rich phase, Pb3GeO5, also was formed with a polycrystalline
structure and large grain size exhibiting a very rough surface. Finally an unknown oxygen
and/or lead deficient phase, which is considered here a non-stoichiometric phase of
Pb5Ge3O11, appeared with a smaller interplanar spacing of about 9.4 Å compared with
10.68 Å for the Pb5Ge3O11 phase. This unknown phase can co-exist with the c-axis
oriented Pb5Ge3O11 phase and deteriorates its ferroelectric properties. Post deposition
annealing in an oxygen or oxygen plus lead ambient can recover the ferroelectric
properties of this film.
Real Space Observation of Double-Helix DNA Structure Using a Low Temperature Scanning Tunneling Microscopy
Authors: Kanno Takashi , Tanaka Hiroyuki , Nakamura Tomohiko , Tabata Hitoshi , Kawai Tomoji
Published: October 2002

Reproducible, reliable and high resolution low temperature scanning tunneling
microscopy (LT-STM) images of plasmid DNA (deoxyribonucleic acid) (2739 bp),
deposited on a well-defined Cu(111) substrate using pulse injection method under
ultra-high vacuum (UHV) condition, have been obtained by using a novel sample preparation
technique. These particular low temperature LT-UHV-STM images have revealed the
double-helix structures of the DNA that have not been resolved earlier.
Optical Compensation of Liquid Crystal Materials Using Negative Birefringence Compensation Films
Authors: Hoke Charles D. , Mori Hiroyuki , Bos Philip J.
Published: October 2002

A unique optical compensation film, based on a negative birefringence material, is shown
to significantly improve the viewing angle characteristics of liquid crystal display (LCD)
devices. A super-twist nematic (STN) LCD was used as basis for our numerical simulations.
The performance of the negative birefringence compensation film for the STN LCD was
modeled using a 4×4 matrix calculation and then compared with the ideal positive birefringence
compensator of the double layer STN (D-STN).
Near Field Magneto-Optical Circular Dichroism Using an Apertureless Probe
Authors: Olivier Bergossi Olivier Bergossi , Hervé Wioland Hervé Wioland , Sylvain Hudlet Sylvain Hudlet , Régis Deturche Régis Deturche , Pascal Royer Pascal Royer
Published: October 2002

We present an original magneto-optical Scanning Near-field-Optical
Microscope (SNOM) configuration, using an apertureless probe, and
devoted to the characterization in transmission of magnetic
samples. Our experimental device provides simultaneously the near
and far field optical images, in Magneto-optical Circular
Dichroism mode (MCD), and the sample surface topography. The
preliminary near field images of an iron garnet test-sample reveal
surface modifications in the magnetic domain distribution,
unresolved in the far field image, and unrelated to the
topographic features. The near field image resolution reaches 240
nm, corresponding to the theoretically estimated size of the
smallest magnetic structures.
Electric-Field-Induced Orientation of Organic Microcrystals with Large Dipole Moment
Authors: Fujita Satoshi , Kasai Hitoshi , Okada Shuji , Oikawa Hidetoshi , Fukuda Takashi , Matsuda Hiro , Tripathy Sukant K. , Nakanishi Hachiro
Published: October 2002

The microcrystals of molecules with large dipole moment in a non-centrosymmetric crystal
structure should possess a huge dipole moment. Therefore, such polar microcrystals dispersed in
nonpolar liquid may easily respond to a weak electric field and orient to it. On the basis of this idea,
dimethylaminostilbazolium tosylate (DAST) microcrystals dispersed in decahydronaphthalene have
been prepared, for which a rather large dipole moment and non-centrosymmetric crystal structures
was confirmed. Absorption change of DAST microcrystals was observed even under a extremly
weak DC electric field of 100 V·cm-1 and the magnitude of absorption change rate at absorption
maximum varied almost linearly up to 300 V·cm-1. This phenomenon may be applied to display
devices.
Highly Conducting Undoped µc-SiO:H Films Prepared by RF Glow Discharge
Authors: Das Debajyoti , Barua Asok K.
Published: October 2002

Highly conducting undoped µc-SiO:H film of σD=3×10-2 S·cm-1,
ΔE=0.14 eV and σPh=8×10-3 S·cm-1 was obtained from high
H2-diluted plasma at a moderately high RF power and substrate
temperature (T
s) by the plasma enhanced chemical vapour
deposition (PECVD) process. At higher T
s and in improved
µc-networks H-content reduced, however, O-incorporation
increased. Crystallinity of the films was identified by Raman
scattering and transmission electron microscope (TEM) studies.
Sharp crystallographic rings in the electron diffraction pattern
identified (111), (220), (311) planes of c-Si and the TEM
micrograph exhibited a uniform and dense distribution of
crystallites with a range of diameters from 50–200 Å.
High-Pressure Phase Transformation of Cobalt Monoxide Due to Electronic Transition
Authors: Noguchi Yuichi , Atou Toshiyuki , Kondo Tadashi , Yagi Takehiko , Syono Yasuhiko
Published: October 2002

High-pressure behavior of rocksalt-type CoO was investigated by shock and static
experiments up to 106 and 131 GPa, respectively. A phase transition was detected at 81±1 GPa
from the measurements of shock compression curve. X-ray diffraction study under static high-pressure revealed two phase transitions at about 80 GPa and 120 GPa. The crystal structure of both
high-pressure phases was closely related to the rocksalt structure. The volume decrease
accompanied by the phase transition was estimated to be about 5%. The high-pressure phase was
reversibly transformed to the ambient phase on unloading. From comparison of recent first
principle calculations, electronic transition with magnetic collapse in Co2+ was inferred.
Terahertz Response with Gradual Change from Square-Law Detection to Photon-Assisted Tunneling in Triple-Barrier Resonant Tunneling Diodes
Authors: Yukio Oguma Yukio Oguma , Nobuo Sashinaka Nobuo Sashinaka , Masahiro Asada Masahiro Asada
Published: October 2002

Current change under irradiation of a terahertz electromagnetic wave was measured for a triple-barrier resonant tunneling diode integrated with a planar patch antenna.
Gradual change from the classical square-law detection to photon-assisted tunneling with increasing photon energy was observed.
Controlled Microwave Irradiation for the Synthesis of YBa 2Cu 3O7-x Superconductors
Authors: Katsuyuki Naitoh Katsuyuki Naitoh , Tokihiro Takizawa Tokihiro Takizawa , Takehiro Matsuse Takehiro Matsuse
Published: October 2002

For synthesizing a high-quality YBa2Cu3O7-x

superconductor using a domestic microwave oven without any post-heat
treatment, the power and time of microwave irradiation are controlled by
monitoring continuously the temperature of the microwave-heated sample.
The temperature is measured by means of a metal-sheathed chromel-alumel
thermocouple which is installed in the oven in the proper way. The
conditions of the sample inside the oven are almost the same as the
sample environment proposed by Kato et al. [Jpn. J. Appl. Phys.
36 (1997) L1291]. The maximum monitoring temperature where
crystal growth occurs rapidly for a high-quality YBa2Cu3O7-x

superconductor is shown to be about 500°C which is much lower
than the maximum heating temperature in the conventional method.
Uniformity of Overdamped NbCN/TiN/NbCN Josephson Junctions
Authors: Shoji Hirotake Yamamori
Published: October 2002

Uniformity of overdamped Josephson junctions consisting of trilayered
NbCN/TiN/NbCN films has been investigated.
To achieve uniform TiN-film thickness and uniform critical-current
density J

c
for junctions, we introduced substrate-holder rotation in the fabrication process of TiN films.
As a result, variation of TiN-film thickness over a distance of 60 mm on a wafer was reduced to ±1.9% and that of J

c
for junctions to ±5%.
With an increase in TiN-film thickness from 40 nm to 65 nm, J

c
decreased from 5.6 ×108 A/m2 to 1.7 ×108 A/m2 and the product of critical current I

c
and normal-state resistance R

n
for junctions decreased from 100 µV to 10 µV.
Local Transport Property on Ferromagnetic Tunnel Junction Measured Using Conducting Atomic Force Microscope
Authors: Ando Yasuo , Kameda Hiroshi , Kubota Hitoshi , Miyazaki Terunobu
Published: October 2002

The local topographical and electrical properties were measured simultaneously for a
Ni80Fe20/Co/Al-oxide junction. Images with a lateral resolution of 1 nm and a current
sensitivity of 3 pA were successfully obtained; no strong correlation between them was
observed. From the results of local current-voltage characteristics also measured, it was
clarified that the contrast of the current image indicated the distribution of barrier heights. The
histogram of current density calculated by taking into consideration a Gaussian distribution
corresponded qualitatively to the experimental result.
Energy Transfer Characteristics in Yb3+- and Tm3+-Doped Fluoride Glass
Authors: Mita Yoh , Kawashima Hideyuki , Sawanobori Naruhito
Published: October 2002

Energy transfer processes from Yb3+ to Tm3+ ions have been examined in fluoride glass to
investigate the effect of the host material and also to explore the applicability limit of the
conventional rate equation model in rare-earth-ion-doped materials. It has been demonstrated
that the energy transfer coefficient increases monotonically with increasing Yb3+ ion
concentration. The results have been compared with the results obtained for several fluoride
crystalline host materials. It has been proved that the dependence of the energy transfer
coefficient upon the donor concentration is distinctly greater in fluoride glass than in fluoride
lattices.
Growth of Carbon Nanotubes on Quartz Plates by Chemical Vapor Deposition Using (Ni, Fe)- Phthalocyanines
Authors: Hisashi Araki Hisashi Araki , Hirotake Kajii Hirotake Kajii , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Carbon multiwall nanotubes were formed on quartz plates by vacuum chemical vapor deposition at 700°C using (Ni, Fe)-phthalocyanines (Pcs) as source materials. From FePc, two types of nanotubes were obtained. The first were the usual tubes whose tips were coiled, as obtained from NiPc, and the second were straight bundles of tubes of equal length shaped like winter mushrooms. Most of the mushroom shaped tubes strongly adhered to the substrate in contrast to the usual tubes. This adhesion was inferred to be induced by the contents (Fe metal) inside the base of the tube.
Preparation of Electrically Conducting Polyanilines by a New Method and Electrical Conducting Properties of the Polymers
Authors: Yamamoto Takakazu , Nurulla Ismayil
Published: October 2002

Palladium-catalyzed polycondensation between
N,N
′-dichloro-p-benzoquinone diimines and diorganometallic aromatic compounds
provides a new route for the synthesis of polyanilines. A polymer
composed of dimethyl-p-benzoquinone diimine and thiophene units has an
electrical conductivity of about 1 S·cm-1 at room temperature, and the
temperature dependence of the electrical conductivity follows a
variable-range-hopping-type equation.
Overdamped NbN Josephson Junctions Based on Nb/AlOx/Nb Trilayer Technology
Authors: Iwai Takao , Aoyama Takashi , Oke Ryutaro , Akaike Hiroyuki , Fujimaki Akira , Hayakawa Hisao
Published: October 2002

We have fabricated overdamped NbN Josephson junctions based on Nb/AlO
x
/Nb
trilayer technology. The junctions have the structure of NbN/Nb/AlO
x
/Nb/NbN,
where Nb/AlO
x
/Nb acts as a junction barrier. The overdamped junctions showed a critical current density J
c and characteristic voltage as high as 0.44 kA/cm2 and 160 µV
at 10 K, respectively. The junction characteristics at 4.2 K were investigated from the
viewpoint of their dependence on the film thickness of the Nb layers. The junction
uniformity was also evaluated. The standard deviation, 1-σ, was 2.1% for a series of
64 5×5 µm2 junctions at 4.2 K.
Self-Shortening of Femtosecond Laser Pulses Propagating in Rare Gas Medium
Authors: Koprinkov Ivan G. , Suda Akira , Wang Pengqian , Midorikawa Katsumi
Published: October 2002

Self-shortening of high-intensity femtosecond pulses in rare gases Ar and Kr has been found at
normal dispersion conditions. The self-shortening results in soliton formation due to
the medium nonlinearity higher than the third-order, which is the first experimental observation of such type of
soliton. A new compression technique, scalable for high-energy femtosecond pulses, has been
achieved based on this phenomenon.
Shallow-Trench Isolation With Raised-Field-Oxide Structure
Authors: Chen Coming , Chang Chun-Yen , Chou Jih-Wen , Lur Water , Sun Shih-Wei
Published: October 2002

This paper describes a novel shallow-trench isolation (STI)
structure to suppress the corner metal-oxide semiconductor
field-effect transistor (MOSFET) inherent to trench isolation. A gate
oxide and a thin polysilicon layer are first processed, and are then
followed by the STI process. With this raised-field-oxide structure,
the anomalous subthreshold conduction of the shallow-trench isolated
MOSFETs due to electric-field crowding at the active edge has been
successfully eliminated. No inverse-narrow-width effect is observed as
the device width has been scaled down to 0.3 µm. The
raised-field-oxide structure provides a larger process margin for
planarization, and good device characteristics were achieved by this
novel STI structure.
Electrical and Structural Characterizations of Cu(InGa)Se2 Thin Films Using Electrochemical Capacitance–Voltage Method and Focused-Ion Beam Process
Authors: Shimizu Akira , Yamada Akira , Konagai Makoto
Published: October 2002

The electrochemical capacitance–voltage (ECV) method and the focused-ion beam (FIB)
process were adopted for the evaluation of device-quality Cu(InGa)Se2 (CIGS) films. The
profiling of the carrier concentrations and the structural properties were successfully carried
out by the ECV and FIB methods, respectively. It was found from the ECV measurements that
the hole concentration of CIGS film grown by the selenization method
was in the order of 1017 cm-3. Furthermore, the FIB process
showed that the CIGS films grown by the selenization method had voids
in the film. These results indicate that both methods are practical
and effective tools for characterizing the CIGS thin films.
Magnetoluminescence Studies of Highly Packed InGaAs Self-organized Quantum Dots on GaAs(311)B
Authors: Akahane Kouichi , Lan Shen , Kawamura Takahiro , Takamasu Tadashi , Kido Giyuu , Okada Yoshitaka , Kawabe Mitsuo
Published: October 2002

We have fabricated a highly packed and ordered In0.4Ga0.6As quantum dots (QDs) array on
GaAs(311)B substrate. In order to investigate the lateral coupling of
QDs, we have carried out photoluminescence and magnetoluminescence
measurement to evaluate the optical properties of these QDs. A large
energy shift dependence on magnetic field was observed from a sample
in which the QDs surface coverage was almost 100%. These results
indicate a possibility that the QDs are coupled laterally, and the
photo-generated carriers and excitons can move within the
two-dimensional plane over distances larger than QDs size.
Conversion of Diamond-Like Carbon Film from Phenylcarbyne Polymer under Pulsed Green Laser Irradiation
Authors: Huang Su Mei , Lu Yong Feng , Sun Zhuo
Published: October 2002

The synthesis of diamond-like carbon (DLC) films at room temperature by
Nd:YAG pulsed laser (532 nm) irradiation of a polymer precursor is presented. The
structures of films with the laser fluence were investigated by Raman spectroscopy.
The morphologies of the resulting samples were examined by scanning electron
microscopy (SEM), and the mechanism of DLC phases converted from the polymer is
discussed. Raman spectrum analysis and SEM results indicate that the polymer is
converted into amorphous carbon (a-C:H) phases with fluence from 60 to 650 mJ/cm2
and crystalline diamond in amorphous carbon matrix phases with fluence above 650 mJ/cm2
by pulsed laser irradiation in an argon gas atmosphere. It is proposed that the
conversion of DLC phases is related to the special diamond-like structure of the
polymer, and the laser provides an efficient thermal source.