bluuebunny/crossref_metadata_2025 huggingface dataset:
Redox Behavior of Poly(diphenylamine-4,4′-diyl) in Acidic Aqueous Media and Electronic Properties of the Doped Polymer
Authors: Yamamoto Takakazu , Kim Sang-Bum , Horie Masaki
Published: October 2002

Poly(diphenylamine-4,4′-diyl) receives electrochemical oxidation with E
pa
of about 0.6 V vs Ag/AgCl with a high doping level (number of positive
charges stored per the repeating unit of the polymer) of about 2 in aqueous
H2SO4 solutions. The oxidized polymer exhibits an electrical conductivity of
0.2 Scm-1 at room temperature and Arrhenius-type plots of the electrical
conductivity give an activation energy of about 0.1 eV. The oxidized polymer
film gives a positive Seebeck coefficient of about 50 µV·K-1.
New Superconducting PbSr2CuO5+δ Prepared by a Novel Low-Temperature Synthetic Route Using Molecular Beam Epitaxy
Authors: Karimoto Shin-ichi , Naito Michio
Published: October 2002

We report the synthesis of a new superconducting cuprate PbSr2CuO5+δ (T
c∼40 K) by a novel low-temperature
synthetic route using molecular beam epitaxy. The new superconductor is the first member of the (Pb-12(n-1)n)
homologous series, which contains a single PbO layer as the charge reservoir block. Low temperature synthesis by molecular beam epitaxy (MBE)
and an appropriate choice of lattice-matched substrates are essential to our discovery of PbSr2CuO5+δ superconductor.
This work demonstrates that MBE opens up a novel synthetic route for new cuprates.
Thermal Annealing of GaInNAs/GaAs Quantum Wells Grown by Chemical Beam Epitaxy and Its Effect on Photoluminescence
Authors: Kageyama Takeo , Miyamoto Tomoyuki , Makino Shigeki , Koyama Fumio , Iga Kenichi
Published: October 2002

The thermal annealing effect on the photoluminescence (PL) characteristics of
GaInNAs/GaAs quantum wells (QWs) grown by chemical beam epitaxy (CBE) using radical
nitrogen is presented. The room-temperature PL peak intensity of GaInNAs/GaAs QWs increased
about 70 times and the linewidth of PL spectra decreased after annealing at 675°C for 30 seconds.
The blue shift of the PL peak wavelength of GaInNAs/GaAs QWs and GaNAs/GaAs QWs, due to
the structural change of QWs was observed. It was found that the blue shift was caused by In–Ga
interdiffusion rather than nitrogen atom diffusion. The interdiffusion caused by defects is thought
to reduce the number of non radiative centers, resulting in the improvement of PL characteristics.
The optimum annealing temperature depends on the composition.
Titanium Silicide Formation and Anneal Using a Susceptor-Based Low Pressure Rapid Thermal Processing System
Authors: Yoo Woo Sik , Atanos Ashur J. , Whitworth David M.
Published: October 2002

Titanium silicide formation and annealing processes were investigated as afunction of
process temperature (600°C–850°C), Ti film thickness (27.5 nm–100 nm) and process
time (45 s–87 s) using a susceptor-based low pressure rapid thermal processing (RTP)
system. Highly reliable, low resistance, production worthy titanium silicide contact
formation and annealing processes have been demonstrated. Excellent sheet resistance
uniformity and repeatability have been demonstrated. The difference in wafer heating
mechanism between the susceptor-based RTP and the lamp-based RTP systems and its
implication to the process results were discussed. Power consumption and productivity were
also described from the production point of view.
Direct Current Heating Induced Giant Step Bunching and Wandering on Si(111) and (001) Vicinal Surfaces
Authors: Masashi Degawa Masashi Degawa , Hozumi Nishimura Hozumi Nishimura , Yasumasa Tanishiro Yasumasa Tanishiro , Hiroki Minoda Hiroki Minoda , Katsumichi Yagi Katsumichi Yagi
Published: October 2002

Direct current (DC) heating induced giant step bunching and wandering on
Si(111) and (001) vicinal surfaces were newly found. The step bunching and wandering
are so large that they can easily be studied by optical microscopy. Temperature
dependence of the DC heating effects and the dependence of such effects on the
crystallographic direction of the current were studied.
1.3 µm InGaAs/InAlGaAs Strained Quantum Well Lasers on InGaAs Ternary Substrates
Authors: Otsubo Koji , Nishijima Yoshito , Uchida Toru , Shoji Hajime , Nakajima Kazuo , Ishikawa Hiroshi
Published: October 2002

InGaAs/InAlGaAs strained quantum well lasers with 1.3 µm
wavelength have been realized on In0.31Ga0.69As ternary substrates for the first
time, owing to the increased indium composition of the substrates. A
temperature-insensitive slope efficiency of -0.007 dB/K has been observed. The
threshold current density (J
th) at 20°C and characteristic temperature (T
0) are
677 A/cm2 and 76 K, respectively. The dependence of T
0 on J
th per well suggests that
higher T
0 would be achieved by fabricating the lasers on InGaAs substrates of
improved quality, thereby decreasing J
th.
Efficient CW Operation of TEM00 Mode from a Diffusive Reflector-Type Diode-Side Pumped Nd:YAG Laser
Authors: Jongmin Lee Jongmin Lee , Hee-Jong Moon Hee-Jong Moon , Jonghoon Yi Jonghoon Yi , Byungheon Cha Byungheon Cha
Published: October 2002

We fabricated a diode side-pumped Nd:YAG laser by using a diffusive
reflector.
In the reflector, 3-fold narrow rectangular slits were made in order to
transfer diode pump power directly
into the diffusive cavity. In a linear short cavity, 190 W multimode
output power
was obtained with the optical efficiency of 43%.
We investigated the characteristics of low mode operation with a linear
dynamically stable resonator.
60 W CW TEM00 output power was obtained when the pump power was
300 W, which corresponds to
the optical efficiency of 20%.
Vibrational Overtone Absorption of Side Chain in Silicone at 1.55 µm Wavelength Band
Authors: Watanabe Toshio , Hayashida Shoichi , Imamura Saburo
Published: October 2002

In order to estimate the propagation loss of a silicone resin optical waveguide at
1.3 µm and 1.55 µm wavelength bands, the absorption spectra of silicone monomers with nondeuterated side chains are examined.
A methyl group imposes an absorption loss around 1.55 µm due to an absorption peak at 1.52 µm, which is assigned to the
combination overtone of C–H symmetric stretching at 2920 cm-1 and methyl C–H rocking deformation at 800 cm-1. We demonstrate
that a cyclohexyl group, which has no fundamental vibration in the 600–850 cm-1 range, exhibits a wider optical window at the
1.55 µm band than the methyl group.
Site-Dependent Fluorescence Decay of Malachite Green Doped in Onion Cell
Authors: Hiroki Nakatsuka Hiroki Nakatsuka , Masaya Hirai Masaya Hirai , Shunji Sekine Shunji Sekine , Yuji Suzuki Yuji Suzuki , Toshiaki Hattori Toshiaki Hattori
Published: October 2002

Time-resolved fluorescence measurements of malachite green dye molecules
doped in onion cells were carried out.
The fluorescence decay time was dependent on the individual cell and on the
position of the dye in a cell, which reflect the microscopic dynamics of each bound
site.
Upon cooling, the decay time increased and this increase was accelerated at
around the freezing point of the onion cell.
Effect of Chemical Structures of Polyimides on Unidirectional Liquid Crystal Alignment Produced by a Polarized Ultraviolet-Light Exposure
Authors: Nishikawa Michinori , Kosa Tamas , West John L.
Published: October 2002

Unidirectional liquid crystal (LC) alignment produced by a polarized ultraviolet-light
(UV) exposure was examined using various polyimides (PIs) which consist of
different tetracarboxylic dianhydrides and diamines. The photosensitivity and anchoring
energy of the LC alignment as a function of UV dosage are summarized with respect to
the chemical structures of the PIs. The results suggest that the UV absorption efficiencies,
molecular conformations, mechanisms of decomposition, and anisotropic van der Waals
forces of the PIs largely affect the photoalignment properties of the LC.
Theoretical and Experimental Considerations on Line-Focus-Beam Acoustic Microscopy for Thin Specimens
Authors: Jun-ichi Kushibiki Jun-ichi Kushibiki , Yuji Ohashi Yuji Ohashi
Published: October 2002

The measurement principle for line-focus-beam acoustic microscopy is
extended to apply to thin specimens taking into consideration
back-reflection effects. The theoretical expressions and interpretation are
given for the apparent and periodic changes in leaky surface acoustic wave
(LSAW) velocity and attenuation with a constant frequency interval Δ
F
1 in the frequency dependence at a chosen measurement position.
The validity of taking moving average with a moving period ±Δ
F
1/2 to obtain true measurement values is proven, and followed by
experiments for a Y-cut, X-propagating MgO:LiNbO3 wafer
specimen with 505.6-µm thickness.
Scaling Parameter Dependent Drain Induced Barrier Lowering Effect in Double-Gate Silicon-on-Insulator Metal-Oxide-Semiconductor Field Effect Transistor
Authors: Samudra Ganesh , Rajendran Krishnasamy
Published: October 2002

A simple model equation to study the effect of drain induced barrier lowering
(DIBL) parameters on device performance for a double-gate (DG) silicon-on-insulator
(SOI) metal-oxide-semiconductor field effect transistor (MOSFET) is proposed. This
model equation is used to study the influence of various device parameters on the DIBL
effect. The main conclusions drawn from the present study are that: (1) two different
approaches for determining the DIBL parameter lead to the same model equation and
(2) it is easier to calculate the DIBL parameter rather than extract it from the I-V plots.
This model is also easy to implement in a circuit simulator. It is found that the DIBL
parameter is almost inversely proportional to the channel length and directly
proportional to the gate oxide and silicon thickness. It is shown that a DIBL parameter
of less than 0.1 down to a gate length of 0.1 µm is possible at lower Si thicknesses.
Diffusion Bonded KTiOPO4 Crystal for the Second Harmonic Generation of High Average Power Zigzag Slab Nd:YAG Laser
Authors: Tei Kazuyoku , Kato Masaaki , Matsuoka Fumiaki , Niwa Yosito , Maruyama Yoichiro , Matoba Tohru , Arisawa Takasi
Published: October 2002

For the second harmonic generation (SHG) of a high-repetition rate and high pulse energy zigzag slab Nd:YAG laser, the direct
bonding of two KTiPO4 (KTP) crystals is carried out and their characteristics are studied using the zigzag slab laser that
produces 2.1 J energy pulses with a beam having a rectangular cross section at a pulse repetition rate of 100 Hz. Although an angle
mismatch of four minutes between two tuning curves is observed for the bonded crystals, the energy conversion efficiency is the
same as that of a single KTP crystal. The second harmonic produced is 1 J.
Expansion Behavior of Bubbles in Silica Glass Concerning Czochralski (CZ) Si Growth
Authors: Huang Xinming , Kishi Hiroshi , Oishi Shuji , Watanabe Hiroyuki , Sanpei Keiko , Sakai Susumu , Hoshikawa Keigo
Published: October 2002

The expansion behavior of bubbles in silica glass concerning Czochralski silicon
crystal growth has been investigated. It is found that most of the bubbles expand considerably under an Ar atmosphere of 20 Torr and 1500°C. The bubble
expansion can be classified into three groups. The first group shows huge
expansion which is related to the existence of carbon in the silica glass. In the
second group the expansion seems to obey some rule, and most of the bubbles in
the silica glass undergo this kind of expansion. The expansion shown by the
second group is called normal expansion in this work. The normal expansion
depends on the silica material. In the third group some bubbles expand only
slightly, and this kind of expansion occurs only near the surface of the glass.
Effect of Polarization Field on Intersubband Transition in AlGaN/GaN Quantum Wells
Authors: Suzuki Nobuo , Iizuka Norio
Published: October 2002

The effect of the built-in field caused by the piezoelectric effect and the spontaneous polarization inherent in nitride quantum wells on the intersubband transition (ISBT) is studied. Measured intersubband absorption wavelengths of Al0.65Ga0.35N/GaN multiquantum wells suggest the existence of a strong field of about 2 MV/cm. For thick wells, the built-in field in the well reduces the effective well width, which drastically shortens the ISBT wavelength and increases the intersubband relaxation time. For thin wells, the strong field in barriers reduces the effective barrier height, which affects the formation of the second subband. Reduction in the field strength in the barriers is important in achieving a short wavelength ISBT.
Intracavity Difference Frequency Generation Using Dual-wavelength Oscillation by an Electronically Tuned Ti:Sapphire Laser
Authors: Saito Norihito , Monma Susumu , Urata Yoshiharu , Wada Satoshi , Tashiro Hideo
Published: October 2002

Tunable mid-infrared radiation was generated by difference frequency mixing
in a MgO:LiNbO3 crystal placed in a dual wavelength Ti:sapphire laser controlled
with an acousto-optical device. A wavelength range from 2.77 to 5.04 µm was
demonstrated by tuning the pump pulse of a longer wavelength in coupling with the
rotation of the mixing crystal, while the shorter wavelength pulse was fixed at three
selected wavelengths of 703, 711 or 719 nm. The maximum average power was
250 µW and the fluctuation was ±10% at 3.05 µm.
High-Power 0.8 µm InGaAsP/InGaP/AlGaAs Single Quantum Well Lasers with Tensile-Strained InGaP Barriers
Authors: Fukunaga Toshiaki , Wada Mitsugu , Hayakawa Toshiro
Published: October 2002

We report the high-power operation InGaAsP/InGaP/AlGaAs separate confinement
heterostructure single quantum well laser diodes of 0.8 µm wavelength with InGaAsP
unstrained quantum well sandwiched by tensile-strained InGaP barriers grown on a GaAs
substrate. High band-gap 0.6% tensile-strained barriers are used to form a
low-absorption region of lasing light near a facet and to suppress the carrier leakage from a
quantum well. The lasers with tensile-strained barriers show performance superior to
those without tensile-strained barriers. The former have a record-high characteristic
temperature of 226 K in the case of 0.78–0.87 µm laser diodes with Al-free active regions
and a high maximum continuous-wave (CW) output power of 1.63 W, while the latter
have a characteristic temperature of 186 K and a maximum CW output power of 1.28 W.
Structural Analysis of a Carbon Nitride Film Prepared by Ion-Beam-Assisted Deposition
Authors: Hayashi Toshiyuki , Matsumuro Akihito , Muramatsu Mutsuo , Kohzaki Masao , Takahashi Yutaka , Yamaguchi Katsumi
Published: October 2002

The microstructure of a carbon nitride (CN
x
) film formed
by ion-beam-assisted deposition (IBAD) was investigated by
transmission electron microscopy (TEM). This film was formed on
the Si (100) substrate by IBAD with an N/C transport ratio of 1.
Three different spacings (0.34 nm, 0.21 nm, 0.12 nm) were observed
by transmission electron diffraction (TED) and the periodic
structure corresponding to the spacing of 0.34 nm was aligned
perpendicular to the substrate. The bending of this plane resembled
a carbon nanotube; therefore, it seemed reasonable to suppose that
the CN
x
film obtained consisted of numerous carbon-nanotube-like
structural elements grown vertically, relative to the substrate,
and it also seemed appropriate that these structural elements
should be termed nanotube-like carbon nitride.
Ge Selective Growth on (001) GaAs Substrates by Molecular Beam Epitaxy
Authors: Inada Mitsuru , Hori Hidenobu , Yamada Syoji
Published: October 2002

Ge selective growth on SiO2 patterned (001) GaAs substrates by molecular beam epitaxy (MBE)
is demonstrated for the first time. Ge films were grown at substrate temperatures of T
s=500–600°C.
In these growth conditions, Ge was grown epitaxially on the GaAs window regions,
while numerous Ge grains were observed on the SiO2 mask. For the sample of T
s=600°C, these
grains could be removed easily, resulting selective Ge growth only on the window region. All Ge
films have p-type conduction. This is caused by interdiffused Ge and Ga atoms, which is
confirmed by secondary ion mass spectroscopy (SIMS) analysis.
Crossover Energy Where Cathodoluminescence Becomes Comparable to Electroluminescence in p-Type GaAs Observed by Injecting Tunneling Electrons
Authors: Sasaki Susumu , Murashita Tooru
Published: October 2002

Using a conductive and transparent tip, which can bear higher bias
voltages than a conventional scanning tunneling microscopy (STM) metal tip, for injecting tunneling
electrons, we successfully obtained the dependence of luminescence
intensity on excitation energy up to 7 eV for p-type GaAs. We found a
threshold energy at 4.9 eV above which the luminescence intensity
substantially increases. The increase is attributable to
cathodoluminescence due to the recombination of electrons and holes
created by impact ionization (I.I.). The present result experimentally
supports the simulation result predicting that there is no clear-cut
transition, but a soft crossover, in the energy dependence of I.I. rate.
Synthesis of Silicon Oxide Nanofibers by Sublimation of SiC in Medium Vacuum with Oxygen Flow
Authors: Hirofumi Takikawa Hirofumi Takikawa , Miki Yatsuki Miki Yatsuki , Tateki Sakakibara Tateki Sakakibara
Published: October 2002

Silicon carbide (SiC) particles with/without cobalt (Co) powder as catalyst were heated on a carbon (C) boat at temperatures ranging from 1,300 to 1,550°C for 10 min in medium vacuum with low oxygen (O2)
flow rate. A large quantity of fiberlike products was found on the SiC particles. The products were observed using a high-resolution scanning electron microscope (HR-SEM) and a high-resolution transmission electron microscope (HR-TEM). Their compositions were also analyzed by electron diffraction analysis, energy dispersive X-ray spectroscopy (EDX) equipped with HR-TEM, and X-ray diffraction (XRD) analysis, to be amorphous SiO2.
Phosphorescent Emission from Polymeric Light-Emitting Diodes Doped with Chrysene-d12
Authors: Blumstengel Sylke , Dorsinville Roger
Published: October 2002

We present electroluminescence studies of chrysene-d12 which has both high phosphorescence (ϕPh=25%) and high fluorescence quantum yields (ϕFl=40%) (at 77 K). Light-emitting
diodes were fabricated utilizing a simple single layer device structure consisting of a hole-transporting polymer matrix poly(methylphenylsilane) doped with chrysene-d12. We show that the
spectrum, temperature dependence and temporal characteristics of the electroluminescence
emission indicate that it originates from the triplet excited state of chrysene-d12.
Spin Relaxation of Electrons in Graded Doping Strained GaAs-Layer Photocathode of Polarized Electron Source
Authors: Zhen Wendong , Matsuyama Tetsuya , Horinaka Hiromichi , Wada Kenji , Nakanishi Tsutomu , Okumi Shoji , Kato Toshihiro , Saka Takashi
Published: October 2002

A graded doping structure is introduced in the strained GaAs layer of a photocathode in
order to realize a highly polarized electron source. The graded doping produces an internal
electric field which moves photoexcited electrons toward the surface. Spin relaxation time
and life time of photoexcited electrons in the graded doping GaAs layer are measured by the
time-resolved photoluminescence method. The spin relaxation due to electron-hole scattering
is suppressed by the transfer of photoexcited electrons toward the surface in a short time.
Improvements of the Optical and Electrical Properties of GaN Films by Using In-doping Method During Growth
Authors: Shen Xu-Qiang , Ramvall Peter , Riblet Philippe , Aoyagi Yoshinobu
Published: October 2002

The optical and electrical properties of GaN films grown by using In-doping method
during growth have been investigated. The GaN films were grown on α-Al2O3(0001)
substrates by gas-source molecular beam epitaxy. X-ray diffraction measurements
illustrate that the quality of GaN films were improved by In-doping.
Photoluminescence measurements at 10 K show that the band-edge related emission
of GaN was enhanced by more than one order of magnitude by this In-doping method,
while the luminescence originating from D-A pair recombination and structural
defects, or possibly oxygen, was reduced. Furthermore, Hall effect measurements at
room temperature (300 K) gave a higher Hall mobility of In-doped samples than
non-doped one. The technique of In-doping during GaN growth looks promising for
improving the optical and electrical properties of optic and electronic devices.
Characteristics of a Metal/Ferroelectric/Insulator/Semiconductor Structure Using an Ultrathin Nitrided Oxide Film as the Buffer Layer
Authors: Sakamaki Kazuo , Hirai Tadahiko , Uesugi Takumi , Kishi Hiroshi , Tarui Yasuo
Published: October 2002

A SrBi2Ta2O9 (SBT) thin film was prepared on a SiON/p-Si(100) substrate at a
process temperature of 700°C. Interdiffusion between the SBT material and Si
substrate was not observed in X-ray photoelectron spectroscopy (XPS) analysis and
in the transmission electron microscope (TEM) image. From the capacitance-voltage
(C-V) measurement, we observed the width of the threshold hysteresis (“memory
window”) of 1.21 V. In the curve fitting of the C-V characteristics, the C-V curve
fitted the curve calculated by the Miller method fairly well. It is considered that
these characteristics are due to the prevention of interdiffusion by the SiON thin
film.
Control of Interdot Space and Dot Size in a Two-Dimensional Gold Nanodot Array
Authors: Shujuan Huang Shujuan Huang , Gen Tsutsui Gen Tsutsui , Hiroyuki Sakaue Hiroyuki Sakaue , Shoso Shingubara Shoso Shingubara , Takayuki Takahagi Takayuki Takahagi
Published: October 2002

Experimental studies on the control of the interdot space and the dot
size in a self-organized two-dimensional array of gold colloidal nanoparticles
encapsulated by alkanethiol are presented. We succeeded in fabricating an
ordered close-packed monolayer of gold nanodots of 5 nm as well as 10 nm
in diameter. In addition, by changing the length of the alkanethiol molecules,
close-packed gold nanodot monolayers with different interdot spaces
were formed. The results of this study indicate a linear relationship between the
interdot space and the length of the alkanethiol molecule, which demonstrates that
the interdot space can be easily controlled by altering alkanethiol molecules.
Production of Single-Wall Nanotubes by High-Temperature Pulsed Arc Discharge: Mechanisms of their Production
Authors: Toshiki Sugai Toshiki Sugai , Hideki Omote Hideki Omote , Shunji Bandow Shunji Bandow , Nobuo Tanaka Nobuo Tanaka , Hisanori Shinohara Hisanori Shinohara
Published: October 2002

Single-wall carbon nanotubes (SWNTs) have been produced for the first
time using the high-temperature pulsed arc-discharge technique,
which has been developed recently in this laboratory,
as reported in the conventional steady arc discharge method.
Scanning electron microscopic (SEM) and transmission electron microscopic (TEM)
observations reveal significant production of bundles of SWNTs in soot.
The pulsed arc production of SWNTs favors a high-temperature
(≥1000°C), long pulses (≥1 ms) and a heavy rare gas such as
Ar or Kr as a buffer gas.
Effects of Ir Electrodes on the Dielectric Constants of Ba0.5Sr0.5TiO3 Films
Authors: Yong Cha Seon , Chul Lee Byung-Tak Jang
Published: October 2002

The effects of an iridium (Ir) electrode on the properties of
Ba0.5Sr0.5TiO3 (BST) films were studied,
in comparison with a conventional platinum (Pt) electrode.
It was found that the dielectric constant of BST films is strongly dependent on
the electrode material.
The BST films deposited on an Ir bottom electrode were preferentially oriented
and showed higher dielectric constants than those on Pt.
Higher dielectric constants of the BST films could also be obtained
by using Ir instead of Pt as a top electrode material,
which was explained as being due to the compressive stress in the BST film
induced by the Ir top electrode.
Low-Temperature Growth of InN Films on (111)GaAs Substrates
Authors: Qixin Guo Qixin Guo , Mitsuhiro Nishio Mitsuhiro Nishio , Hiroshi Ogawa Hiroshi Ogawa , Akira Yoshida Akira Yoshida
Published: October 2002

InN films have been grown on (111)GaAs substrates by radio frequency
magnetron sputtering. It is revealed that epitaxial InN films with
wurtzite structure can be
obtained at a growth temperature as low as 100°C.
InN grown directly on (111)GaAs is highly oriented in the c-plane, but
lacks in-plane uniformity.
A buffer layer formed by presputtering the substrate in nitrogen
plasma can significantly improve the
in-plane orientation, producing single-crystal InN.
GaN on Si Substrate with AlGaN/AlN Intermediate Layer
Authors: Ishikawa Hiroyasu , Zhao Guang-Yuan , Nakada Naoyuki , Egawa Takashi , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

A single crystal GaN thin film was successfully grown on a Si (111) substrate by means of
atmospheric pressure metalorganic chemical vapor deposition. Though there is a large difference in
thermal expansion coefficients between GaN and Si, an intermediate layer consisting of AlN and
AlGaN improved the quality of GaN on Si and reduced meltback etching during growth. Pits and
cracks were not observed on the substrate and a mirror-like surface was obtained. The full-width at half
maximum (FWHM) of the double-crystal X-ray rocking curve for GaN(0004) was 600 arcsec.
Photoluminescence measurement at room temperature for a Si-doped film revealed a sharp band-edge
emission with a FWHM of 62.5 meV, which is the narrowest value reported to date.
Current Fluctuation Characteristic of Sub-0.1 Micron Device Structures: A Monte Carlo Study
Authors: Sano Nobuyuki , Natori Kenji , Matsuzawa Kazuya , Mukai Mikio
Published: October 2002

Monte Carlo simulations of current fluctuation in Si n-i-n diode structures are carried out with various lengths of theintrinsic(channel) region so that electron transport under diffusive and quasi-ballistic regimes is covered. It is shown that a new current fluctuation mode associated with the fluctuation in the number of electrons in the channel region appears in sub-0.1 µm device structures. This is caused by the diffusion of high-energy electrons in the anode n-doped region, and is characteristic of sub-0.1 µm device structures since high-energy electrons in the anode originate from quasi-ballistic transport in the channel.
Studies of the Oxygen Deficiency Effect in La1-xCaxMnOz Using X-ray Photoelectron Spectroscopy
Authors: Hayashi Ken-ichi , Wada Hideo
Published: October 2002

Oxygen 1s photoelectron spectra have been measured for
La1-x
Ca
x
MnO
z
(LCMO) thin films. The results on the second
peak shift and the separation of the peaks are discussed. The second
peak shift indicates the oxygen increase causing magnetic transition.
The separation of the peaks shows that the oxygen stoichiometry in
the crystal is improved. This tendency confirms that the amount of
activated oxygen increases with annealing temperature. It is
considered that the oxygen 1s photoelectron spectra and the oxygen
deficiency effect in resistivity measurements are significantly related.
Tensile Strain Introduced in AlN Layer Grown by Metal-Organic Vapor-Phase Epitaxy on (0001) 6H-SiC with (GaN/AlN) Buffer
Authors: Kurimoto Makoto , Nakada Toshiyuki , Ishihara Yoshiyuki , Shibata Masao , Honda Tohru , Kawanishi Hideo
Published: October 2002

An AlN layer with tensile strain along the a-axis was grown on a (0001) 6H-SiC substrate
with a (GaN/AlN) buffer layer by metal-organic vapor-phase epitaxy using an alternating source
feeding technique. It was experimentally demonstrated that the strain in the AlN layer was
affected by the buffer layer structure. On the other hand, the AlN layer grown directly on a
substrate without the buffer layer exhibits compressive strain along the a-axis. Strain control in
the AlN layer by adjusting the buffer layer structure is proposed.
Effect of Oxygen Plasma Treatment on Hydrogen-Damaged Pt/Pb(ZrxTi1-x)O3/Pt Ferroelectric Thin-Film Capacitor
Authors: Park Youngsoo , Lee June Key , Chung Ilsub , Lee Jai-Young
Published: October 2002

Electron cyclotron resonance (ECR) oxygen plasma treatment of the
Pt/Pb(Zr
x
Ti1-x
)O3/Pt capacitor was attempted to reduce the property degradation due to
hydrogen. It was found that oxygen plasma treatment using ECR modifies the surface
of Pt electrodes. Surface modification deteriorates catalytic activity of Pt electrodes,
thereby significantly improving ferroelectric properties such as remnant polarization
and leakage current. It seems that highly reactive oxygen radicals in ECR plasma play
an important role in deteriorating the catalytic activity of Pt electrodes.
Relationship between Flexoelectricity and Helical Pitch in Ferroelectric Liquid Crystal Mixtures Containing Host Achiral Compounds and Chiral Dopants
Authors: Takanishi Yoichi , Yokoyama Jun , Ishikawa Ken , Takezoe Hideo , Fukuda Atsuo , Orihara Hiroshi , Osipov Mikhail A.
Published: October 2002

The helical pitch as a function of the molar ratio of chiral dopants
was discussed based on the host-host, host-dopant and dopant-dopant flexoelectric interactions in a ferroelectric liquid crystal
mixture system. It was found that the wavenumber of the pitch
approximately changes from quadratic to cubic dependence on the
chiral dopant ratio and that the host-dopant flexoelectric
interactions are negligible compared with the host-host and
dopant-dopant interactions.
Epitaxial Growth of Zinc Oxide Whiskers by Chemical-Vapor Deposition under Atmospheric Pressure
Authors: Minoru Satoh Minoru Satoh , Norio Tanaka Norio Tanaka , Yoshikazu Ueda Yoshikazu Ueda , Shigeo Ohshio Shigeo Ohshio , Hidetoshi Saitoh Hidetoshi Saitoh
Published: October 2002

ZnO whiskers were epitaxially grown by a chemical-vapor deposition technique
employed at atmospheric pressure.
Highly oriented ZnO whiskers grew at a substrate temperature of
550°C on (0001)α-Al2O3 substrates
with a growth rate of 3.7 nm/s.
X-ray diffractometry revealed that the epitaxial relationship
between the whiskers and the substrate was determined
as ZnO[1010](0001)//Al2O3[1210](0001)
or ZnO[1210](0001)//Al2O3[1010](0001).
In addition, the full-width at half maximum value of the (0002) reflection was
as low as 0.43°. Images obtained using a scanning electron microscope were analyzed
and it was found that the whisker tip likely has
a radius of curvature of approximately 20 nm.
The typical number density of the whiskers has reached 1.3×105mm-2.
A Digital-to-Analog Converter of Displacement by an Integrated Micromechanism
Authors: Hiroshi Toshiyoshi Hiroshi Toshiyoshi , Dai Kobayashi Dai Kobayashi , Makoto Mita Makoto Mita , Gen Hashiguchi Gen Hashiguchi , Hiroyuki Fujita Hiroyuki Fujita , Junji Endo Junji Endo , Yasuo Wada Yasuo Wada
Published: October 2002

We have newly invented a micromechanism for precise position
control, which is equivalent to that of an electrical
digital-to-analog converter(DAC) of the R-2R resistor network.
The micromechanical C-2C compliance suspension network has been
fabricated on a silicon-on-insulator wafer by a micromachining
technique. When N-bit digital driving voltages are applied to
the micromechanism, cascaded electrostatic microactuators produce
a set of displacements of ±1 µm. These displacements
accumulate in the suspension network with binary weights to
synthesize DAC-like displacement output. A traveling displacement
of 6 µm is obtained while the positioning resolution is
0.38 µm in the case of 4 bit input. Resolution can be
improved further by increasing the addressing size of the input.
A Measure of Complexity for 1/f Fluctuation
Authors: Takeshi Saito Takeshi Saito , Masahiro Agu Masahiro Agu , Mitsuhiro Yamada Mitsuhiro Yamada
Published: October 2002

A measure of complexity for 1/f
β fluctuation is proposed
using the block entropy of a sequence of correlated symbols
generated by 1/f
β fluctuation.
This measure of complexity represents the diversity of
sequences of correlated symbols.
It is shown that the measure of complexity has the maximum
value for 1/f fluctuation among 1/f
β fluctuations
when the length of sequence of correlated symbols is chosen
appropriately.
Phase Noise Enhancement of the GaAs High Electron Mobility Transistors Using Micromachined Cavity Resonators at Ka-band
Authors: Song Insang , Kim Chungwoo , Kwon Youngwoo , Cheon Changyul , Song Cimoo
Published: October 2002

We introduce a new structure of the micromachined cavity resonator coupled GaAs-based
oscillator to enhance the phase noise and the frequency stability. The oscillator and the
cavity are designed for Ka-band applications. Compared to the free running oscillator, the
cavity resonator coupled oscillator showed the phase noise enhancement of about 20 dB. The
phase noises of about -110 and -85 dBc/Hz are obtained at 1 MHz and 100 kHz offset frequency,
respectively. The frequency pushing for the gate bias of the cavity coupled oscillator is about
two order of magnitude less than that of the free running oscillator.
X-Ray Rocking Curve Determination of Twist and Tilt Angles in GaN Films Grown by an Epitaxial-Lateral-Overgrowth Technique
Authors: Kobayashi Kenji , Yamaguchi A. Atsushi , Kimura Shigeru , Sunakawa Haruo , Kimura Akitaka , Usui Akira
Published: October 2002

X-ray rocking curve measurements have been carried out in order to investigate the
twisting and tilting in hydride vapor phase epitaxy (HVPE) and metalorganic vapor
phase epitaxy (MOVPE) GaN films fabricated by an epitaxial lateral overgrowth (ELO)
technique. The twist angle is directly determined by means of grazing incidence angle
X-ray diffraction. It is found that these angles in both MOVPE and HVPE films are
significantly reduced by the ELO technique especially for the twist angles. In the
MOVPE-ELO GaN film, the tilt and twist angles depend on the stripe direction of the
mask pattern, which is closely related to the difference of the growth process.
Real-Time Observation of Ellipsometry Oscillation during GaAs Layer by Layer Growth by Metalorganic Vapor-Phase Epitaxy
Authors: Lee Jeong-Sik , Sugou Shigeo , Masumoto Yasuaki
Published: October 2002

Ellipsometry oscillations during GaAs metalorganic vapor-phase epitaxy on GaAs (001)
substrates were observed. The ellipsometric signal was found to oscillate at a period
corresponding to 1 monolayer of GaAs growth. Excellent agreement was seen between growth
rate data from oscillation period and those from thickness measurements after growth (deviation:
<1%). Oscillation clearly depends on growth temperature and source gas material. The
results suggest that ellipsometry oscillation originates from the absorption of probe light by
Ga-alkyl bonds at the edges of 2-dimensional islands.
Photostimulated Luminescence of CuCl Quantum Dots in NaCl Crystals
Authors: Yasuaki Masumoto Yasuaki Masumoto , Seitaro Ogasawara Seitaro Ogasawara
Published: October 2002

Photostimulated luminescence (PSL) was observed in CuCl quantum dots embedded in NaCl crystals at low temperatures of up to 120 K. This observation demonstrates that the quantum dot system is a new class of PSL materials. The thermal quenching, spontaneous decay and excitation-fluence dependence of the PSL are almost the same as those of persistent spectral hole burning (PSHB), indicating that the photoionization of quantum dots and the subsequent carrier capture at the traps near the quantum dots bring forth both PSL and PSHB. The traps form a Gaussian band and are considered to arise from Cu+ in NaCl. The requirement for the new class of PSL materials is the presence of quantum dots and nearby carrier traps in the host materials.
Electrically Induced Optical Absorption in Al-CuAlS 2-Au Diode
Authors: Naohiro Ishibashi Naohiro Ishibashi , Takao Nishi Takao Nishi , Naoyuki Hayashi Naoyuki Hayashi , Chihomi Furuhashi Chihomi Furuhashi , Katsuaki Sato Katsuaki Sato
Published: October 2002

Electrically induced change in absorption spectra was observed for the first time in the CuAlS2-Al junction with a Schottky-type contact at 20 K in the wavelength region 600–900 nm. The observed change of absorption is considered to be due to the motion of the Fermi level on applying voltage across the level formed by some charged state at the metal-semiconductor interface.
Interpretation of Difference in Wearless Friction Observed between Ordered Organic Monolayers with CH3 and CF3 Terminal Groups
Authors: Ohzono Takuya , Glosli James N. , Fujihira Masamichi
Published: October 2002

Molecular dynamics and corresponding simple phenomenological simulations are used to
interpret the difference in wearless friction observed between two ordered monolayers with CH3
and CF3 terminal groups of the same alkyl chains bound at their ends to rigid substrates. The
simulated interfaces correspond well to mesoscopic sliding interfaces. The simplified model
previously proposed by us, where the frictional properties at such sliding interfaces are governed
by two potentials which are closely related to the chemical and the structure of the film, suggests
that the above frictional difference can be qualitatively interpreted by the difference in slopes of the
corrugated interfacial potentials between two films at the repulsive regions.
Characteristics of Ultrahigh-Frequency Surface-Wave Plasmas Excited at 915 MHz
Authors: Nagatsu Masaaki , Ito Akira , Toyoda Naoki , Sugai Hideo
Published: October 2002

Characteristics of 40-cm-sized planar plasmas excited at 915 MHz using various types
of slot antennas in Ar and O2 gases are investigated. Axial profiles of the wave
electric field and the electron density clearly reveal that high-density surface-wave
plasmas are easily produced even at relatively low powers: the electron density increases
linearly from 5×1010 cm-3 (the critical density for pure surface-wave mode excitation)
to 6×1011 cm-3 with the net incident power from 100 W to 1 kW at 80 mTorr in Ar.
Thus, the 915 MHz discharge enables one to control the plasma, even at low densities where
a conventional 2.45 GHz surface-wave discharge suffers from unstable density jumps. In
addition, the present results indicate that almost linear plasma production characteristics
are obtained in three types of slot antennas, that is, one inclined slot, a pair of
transverse slots and a combination of two transverse slots and two longitudinal slots.
These advantages of the 915 MHz excitation are due to the critical density being lower
than that of the 2.45 GHz excitation by a factor of seven. A large-area uniform plasma
with a homogeneity of ±5% is obtained for both Ar and O2 discharges over a horizontal
length of about 20 cm at an axial position of z=23 cm away from the top quartz plate just below the slot antennas.
Effect of Slight Misorientation of Sapphire Substrate on Metalorganic Chemical Vapor Deposition Growth of GaN
Authors: Yuasa Takayuki , Ueta Yoshihiro , Tsuda Yuhzoh , Ogawa Atushi , Taneya Mototaka , Takao Katsutoshi
Published: October 2002

The effects of slight misorientation from c-plane (0001) sapphire (α-Al2O3) substrates on GaN surface
morphologies and electroluminescence (EL) properties were studied. The GaN layers were grown using a two-step growth method under
atmospheric pressure by metalorganic chemical vapor deposition (MOCVD). When using around 0.17° misoriented sapphire substrate
tilted toward both <1120> and <1100> directions, a small step-type morphology appeared. On the other hand, using c-plain
substrate or substrates with the misorientation angle larger than approximately 0.25° from the c-plane, a scale-shaped
morphology appears. We also found that the misorientation of the substrate significantly affects the uniformity of the EL image.
On the other hand, the light output powers of the light-emitting diodes (LEDs) fabricated on the substrates with different
misorientations were almost the same in spite of the different surface morphologies.
Preparation of Epitaxial YbBa2Cu3O7-δ on SrTiO3 Single Crystal Substrates Using a Solution Process
Authors: Matsubara Ichiro , Paranthaman Mariappan , Chirayil Thomas G. , Sun Ellen Y. , Martin Patrick M. , Kroeger Donald M. , Verebelyi Darren T. , Christen David K.
Published: October 2002

We have prepared YbBa2Cu3O7-δ (Yb-123) epitaxial films on SrTiO3 (100) single crystal
substrates by a metal organic decomposition (MOD) method. Precursor solution was prepared
by dissolving ytterbium acetylacetonate, barium neodecanoate, and copper (II)
2-ethylhexanoate in a mixture of solvents containing toluene/pyridine/propionic acid. The
precursor solutions were spin coated on the substrates and fired at 730–770°C in 100-ppm
oxygen atmospheres followed by 1 atm O2 annealing. X-ray diffraction results from the theta-2theta,
phi, and omega scans for the films revealed a (100) cubic texture. The full-width-at-half-maximum
values for Yb-123 (103) and Yb-123 (005) were 1.5° (in-plane epitaxy, Δφ)
and 0.73° (out-of-plane epitaxy, Δω), respectively. The highest T
c obtained for Yb-123 films
was 87.2 K. The measured transport J
c was 6.4×105 A/cm2 at 77 K and self-field.
Rotation of Optically Trapped Particles in Air
Authors: Omori Ryota , Shima Kotaro , Suzuki Atsuyuki
Published: October 2002

We have demonstrated optically induced rotation of microscopic dielectric
particles in air. The particles were anisotropically shaped, and were simultaneously
trapped three-dimensionally and rotated about the beam axis, which depended
solely on the radiation pressure of an extremely focused laser light. It was observed
that the rotational speed was linearly dependent on the irradiated beam power and
the slope of the fitting lines revealed up to 860 rpm/mW for 3.0 µm-diameter-particles
and 540 rpm/mW for 4.0 µm-diameter-particles, which was much higher than the
previously reported values measured in water. This technique will be useful for
micromotors and microfans assembled in microelectromechanical systems.
Microfabrication of a Fluoropolymer Film Using Conventional XeCl Excimer Laser by Laser-Induced Backside Wet Etching
Authors: Jun Wang Jun Wang , Hiroyuki Niino Hiroyuki Niino , Akira Yabe Akira Yabe
Published: October 2002

The surface of a fluoropolymer film was fabricated with micron-sized features by laser-induced backside wet etching (LIBWE), using a nanosecond XeCl excimer laser at 308 nm.
The etch rate ranged from 5 to 20 nm/pulse by laser irradiation at fluences varying from 160 to 500 mJ/cm2. The threshold fluence for etching was about 100 mJ/cm2 in the case of a tetrahydrofuran (THF) solution containing pyrene. The mechanism of LIBWE is explained by the formation of superheated liquid in a cyclic multiphotonic absorption process.
Capacitance-Voltage Study of Silicon-on-Insulator Structure with an Ultrathin Buried SiO2 Layer Fabricated by Wafer Bonding
Authors: Ishikawa Yasuhiko , Makita Shigenori , Zhang Jianhua , Tsuchiya Toshiaki , Tabe Michiharu
Published: October 2002

A silicon-on-insulator (SOI) structure with a thin (typically 20 nm) Si layer and an
ultrathin (2 nm) thermally grown buried SiO2 layer, which is a key structure in novel Si devices,
was fabricated in our laboratory by a wafer bonding technique. Transmission electron microscope
observation revealed that the ultrathin buried oxide layer is continuous and uniform in thickness.
For the SOI samples, the effect of direct carrier tunneling through the buried oxide was studied
by capacitance-voltage (C-V ) measurements. The resultant C-V characteristics were found to be
determined by the tunneling probability of carriers through the buried oxide, and band bending in
the SOI layer.
Electrical Properties of Multiple High-Dose Si Implantation in p-GaN
Authors: Lai Wei-Chih , Yokoyama Mesio , Tsai Chiung-Chi , Chang Chen-Shiung , Guo Jan-Dar , Tsang Jian-Shihn , Chan Shih-Hsiung , Chang Chun-Yen
Published: October 2002

This work performs Si ion implantation the electrical conductive type of the p-GaN film from p-type to n-type. Multiple implantation method is also used to form a
uniform Si implanted region in the p-type GaN epitaxial layer. Implant energies for
the multiple implantation are 40, 100, and 200 KeV. The implant dose is 5×1015 cm-2
for each implant energy. After implantation, the samples are annealed in a N2 ambient
for different annealing temperatures and annealing times. The activation efficiency
reaches as high as 20% when annealing the sample at 1000°C. The carrier activation
energy is about 720 meV. The low activation energy indicates that the hopping
process mechanism is the dominant mechanism for the activation of the Si
implantation in p-GaN. Moreover, the rectifying I-V characteristic of the p-n GaN
diode is also examined.
Decay Characteristics of Photoluminescence Lines in CuGaS 2 Crystals
Authors: Terasako Tomoaki , Hiroshi Umiji Hiroshi Umiji , Kunihiko Tanaka Kunihiko Tanaka , Sho Shirakata Sho Shirakata , Hisao Uchiki Hisao Uchiki , Shigehiro Isomura Shigehiro Isomura
Published: October 2002

Time-resolved photoluminescence (PL) measurements have been carried out for CuGaS2 single crystals with a slightly Cu-rich composition grown by an iodine transport method. PL lines at 2.460 eV, 2.457 eV, 2.417 eV, 2.404 eV, 2.397 eV and 2.295 eV exhibited biexponential decay. The relationship between the decay time of the fast component (τ
f
) and the localization energy (E
loc) can be given by
τ
f
∝E
loc
1.25. On the other hand, the decay times of the slow components (τ
s
) have been classified into two groups having different trends τ
s
∝E
loc
2.7 and E
loc
0.5. The difference between the two groups is discussed in terms of native defects and the iodine impurity included in the luminescence centers.
Intraband Relaxation Time in Wurtzite GaN/InAlN Quantum-Well
Authors: Seoung-Hwan Park Seoung-Hwan Park , Doyeol Ahn Doyeol Ahn
Published: October 2002

The intraband relaxation time in a wurtzite GaN/InAlN quantum well (QW) is investigated theoretically as a function of the compressive strain and well thickness. The results are compared with those obtained for an InGaAs/InGaAsP(1.13 eV) QW. It is found that the total linewidth broadening of GaN/InAlN QW is nearly independent of the compressive strain because the in-plane effective masses are not affected by the strain. On the other hand, the total linewidth of an InGaAs/InGaAsP QW significantly decreases with increasing strain. The linewidths for carrier-phonon scattering of a GaN/InAlN QW are much greater than those of an InGaAs/InGaAsP QW. The relaxation times for the electron-phonon and hole-phonon scatterings are estimated to be about 10 and 3 fs, respectively. Also, it is shown that the total linewidth of a GaN/InAlN QW is nearly constant irrespective of the well thickness.
Direct Conversion of Titanium Alkoxide into Crystallized TiO2 (rutile) Using Coating Photolysis Process with ArF Excimer Laser
Authors: Tsuchiya Tetsuo , Watanabe Akio , Imai Yoji , Niino Hiroyuki , Yamaguchi Iwao , Manabe Takaaki , Kumagai Toshiya , Mizuta Susumu
Published: October 2002

TiO2 (rutile) films have been successfully prepared by the coating photolysis process using
ArF excimer laser irradiation at room temperature. The choice of the Ti-alkoxide type as
the starting material and the effects of atmosphere on the product films have been studied
by Fourier transformation infrared (FT-IR) and X-ray diffraction (XRD). When using Ti(O-i-C3H7)4 as the starting material, rutile films were
obtained by the irradiation in a dry N2 atmosphere, whereas amorphous films were
obtained by irradiation in air. When using Ti(OCH2CH(C2H5)-n-C4H9)4 as a starting
material, rutile films were obtained by the irradiation even in the air atmosphere.
Crystallization mechanism is also discussed.
Vacuum Shear Force Microscopy Application to High Resolution Work
Authors: Polonski Vitali V. , Yamamoto Yoh , White Jonathon D. , Kourogi Motonobu , Ohtsu Motoichi
Published: October 2002

A new technique–Vacuum Shear Force Microscopy (VSFM)–is introduced
as a reliable method for maintaining a constant separation between a probe and
sample. Elimination of many of the instabilities observed when applying the shear
force mechanism to imaging under ambient conditions, allows for routine nanometer
lateral and sub-nanometer normal resolution. In this paper this technique is applied,
firstly, to the imaging of microtubules (biology) and, secondly, to the patterning and
subsequent imaging of nanoscale metal lines (nanofabrication).