bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Mold Fabrication for Nano-Imprint Lithography to Fabricate Single-Electron Tunneling Devices
Authors: Hirai Yoshihiko , Kanemaki Yasuhito , Murata Kazuo , Tanaka Yoshio
Published: October 2002

A novel method of fabricating a nano-imprinting mold for a single-electron device is
newly proposed, which makes use of the peculiarity of anisotropic wet chemical etching.
A row of resist patterns for quantum dots is placed to keep an offset angle θ against a
<110> crystalline axis on a (100) Si surface. By an anisotropic wet chemical etching, the
Si substrate is diagonally etched along the <110> and <110> directions, and an
inverted pyramidal hole with a (111) plane surface is formed. The gap between them
becomes narrower than that of the original pattern. Using this method, the nano-imprinting
mold for a quantum dot array with narrow gaps beyond the resolution limit of
conventional lithography is obtained.
Study of Photocurrent Properties of GaN Ultraviolet Photoconductor Grown on 6H-SiC Substrate
Authors: Shen Bo , Yang Kai , Zang Lan , Chen Zhi-zhong , Chen Yu-gangZhou , Zhang Rong , Huang Zheng-chun , Zhou Hao-shen , Zheng You-dou
Published: October 2002

The properties of a photoconductive ultraviolet detector based on a GaN epilayer grown on a 6H-SiC substrate using metal-organic chemical vapor deposition were investigated. We obtained the detectable energy span of the device up to the ultraviolet region by photocurrent measurement. The spectral responsivity remained nearly constant for wavelengths ranging from 250 to 365 nm and dropped by three orders of magnitude within 15 nm of the band edge from 365 nm to 380 nm.The detector was measured to have a responsivity of 133 A/W at a wavelength of 360 nm under a 5 V bias, and the voltage-dependent responsivity was evatuated. Furthermore, a convenient method to determine the response time was developed. The relationship between response time and bias was obtained.
Effects of Peaking Capacitor in a Copper Bromide Vapor Laser
Authors: Tou Teckyong , Siew Weeong , Tham Kwongkeong
Published: October 2002

The performance of a copper bromide vapor laser, continuously excited by a charge transfer circuit at 7 kHz, was studied by varying its peaking capacitor. It was observed that, in contrast to many pulsed
gas lasers, a slower risetime in the breakdown voltage for discharge initiation produced an extended
quasi-steady discharge regime which increased the input power for laser excitation.
Structural Study on Ca0.6Sr0.4ZrO3
Authors: Joseph John , Sivasubramaniam V. , Vimala T. M. , Murthy V. R. K.
Published: October 2002

Structural study on the compound Ca0.6Sr0.4ZrO3 has been carried out. The study
reveals that it is not isomorphous with its parent compounds CaZrO3 and SrZrO3. It
belongs to the space group Pmcn and the size of the unit cell is 2a
p×√ 2b
p×2√ 2c
p. The
tilt system of the BO6 octahedra is found to be compound and the octahedra are highly
distorted. The A-ions are displaced along the [001] direction by about 0.134 Å and
the displacements in adjacent layers are in the opposite directions.
Evaluation of Interface States in ZnO Varistors by Spectral Analysis of Deep Level Transient Spectroscopy
Authors: Ohbuchi Yasuhiro , Yoshino Junya , Okamoto Yoichi , Morimoto Jun
Published: October 2002

Interface states in ZnO varistors were studied using spectral analysis of deep level transient
spectroscopy (SADLTS) to obtain the emission rate spectrum. We found one interface state in ZnO
with the activation energy and the capture cross section distributed around their central values,
E
0=0.98 eV and σ0=1.8×10-16 cm2, over widths ΔE=0.19 eV and Δσ=2.9×10-17 cm2, respectively.
Investigation of Moving Striations in a Low-Pressure Hg–Ar Discharge: I. Evaluation of Electron Temperature near the Reignition Region
Authors: Kajiwara Toshiro , Sano Masatoshi
Published: October 2002

When discharge tubes filled with low-pressure Hg–Ar gas are operated on a
commercial ballast (at 50 or 60 Hz),they generate moving striations with
decreasing ambient temperature. It was considered, in previous studies, that this
phenomenon is caused by the high electron temperature in the reignition region of
ac discharges below the ambient temperature. Saturated Hg vapor pressure
decreases with decreasing ambient temperature. As a result, it is considered that
the kinetic energy of electrons consumed for the excitation and ionization of Hg
atoms decreases rapidly and the electron temperature of the high-energy part Tt,
based on the assumption of a non-Maxwellian distribution function for energetic
electrons, is raised above the excited or ionized levels of Ar gas. It is thought that
this steep rise of the electron temperature in the reignition region induces the
unstable discharges. It is confirmed by ac discharge simulation that the
maximum of Tt values increases with decreasing in ambient temperature and Ar
filling pressure.
X-Ray Radiation of the Plasma Focus with Inverse Pinch Switch
Authors: Choi Woon Sang , Park Duck Kyu
Published: October 2002

X-ray radiation characteristics of the plasma focus with inverse pinch switch was investigated. The plasma focus device power with capability of 20 kJ contains a 40 kV condenser power supply and adopts a new type of switch system, The mechanism of X-ray radiation was analyzed using a pair of detectors. The variation of X-ray radiation as a function of the position of emitted X-ray and the shape of electrode was examined closely using the time-integrated method. By analyzing the mechanism, we found that the X-ray radiation has three peaks in the optimal plasma focus condition with the middle one being m=0 instability.
Visualization of Mode Shapes in Piezoelectric Resonators Using an Electrostatic Microphone
Authors: Watanabe Yasuaki , Niikura Kentaro , Yuan Geng , Goka Shigeyoshi , Sekimoto Hitoshi
Published: October 2002

A method for measuring the mode shapes of quartz crystal resonators using an electrostatic microphone is described. In this method the resonator driving current is strongly modulated, and a needle connected to the microphone picks up the modulation signal on the resonator surface. The vibrational patterns are obtained by mapping the detected modulation signals on the resonator surfaces. The experiments were carried out using AT-cut rectangular quartz plates and the results were compared with those from the calculations.
Automatic Focusing and Astigmatism Correction Method based on Fourier Transform of Scanning Electron Microscope Images
Authors: Ogasawara Munehiro , Fukudome Yuji , Hattori Kiyoshi , Tamamushi Shuichi , Koikari Soshi , Onoguchi Kazunori
Published: October 2002

A new method for automatic focusing and astigmatism correction of electron optics
has been proposed. The method consists of the following 6 steps: (1) Obtain scanning electron
microscope (SEM) images i
1(x,y), i
2(x,y) under two focusing conditions. (2) Obtain Fourier
transformed images of i
1(x,y) and i
2(x,y), I
1(k

x
,k

y
) and I
2(k

x
,k

y
). (3) Obtain a characteristic
function R(k

x
,k

y
)=ln(I
1(k

x
,k

y
)/I
2(k

x
,k

y
)). (4) Repeat the above steps under different focusing
conditions. (5) From the change in R(k

x
,k

y
), calculate the change in beam sharpnesses in
different directions. (6) Correct the astigmatism and adjust the focus. R(k

x
,k

y
) is independent of
the sample shape, and is independent of the beam shape in the case of a character beam.
Therefore, this method can be applied both to a SEM and to an electron beam writer with a
character beam.
Partial Pressure of Phosphorus and Arsenic Vapor Measured by Raman Scattering
Authors: R. Pederson Katrin Roth
Published: October 2002

In-situ Raman scattering results on vapor of phosphorus and arsenic at temperatures up to 1400 K are presented. The ratio of the Raman intensities of different species in the gas is proportional to the ratio of the corresponding partial pressures. The results of this new method for measuring partial pressures will be compared with thermodynamical calculations. The presented method allows the on line monitoring of the vapor atmosphere during crystal growth or annealing processes, which may be important for optimizing growth conditions, doping by the gas phase or quality optimizing of wafers.
Time-Resolved Photoluminescence Study of Strain-Induced Quantum Dots Self-Formed in GaP/InP Short-Period Superlattice
Authors: Fudeta Mayuko , Asahi Hajime , Asami Kumiko , Narukawa Yukio , Kawakami Yoichi , Noh Joo-Hyong , Mori Jun , Watanabe Daisuke , Fujita Sigeo , Gonda Shun-ichi
Published: October 2002

The nature of emission in quantum dot (QD) structures self-formed in GaP/InP short-period
superlattice is investigated in detail by means of time-resolved photoluminescence (TRPL)
spectroscopy. PL decay time strongly depends on emission energy and temperature, and
ranges from 0.1 ns to 2.5 ns, which can be explained by considering the tunneling effect of
carriers and the nonideal dimensionality of dots. The multilayer QD structures with thicker QD
layers show a longer PL decay time of up to 1 µs at low excitation densities, which is
considered to be caused by an internal piezoelectric field.
New Self-Organized Growth Method for InGaAs Quantum Dots on GaAs(001) Using Droplet Epitaxy
Authors: Mano Takaaki , Watanabe Katsuyuki , Tsukamoto Shiro , Fujioka Hiroshi , Oshima Masaharu , Koguchi Nobuyuki
Published: October 2002

Quantum dot (QD) systems for InGaAs/GaAs without a wetting layer
have been fabricated on GaAs (001) surfaces by a new self-organized growth
method using droplet epitaxy with highly dense Ga droplets. Droplets of
InGa alloy with highly dense Ga droplets have been formed by supplying 1)
Ga, 2) In and 3) Ga molecular beams, sequentially. These highly dense Ga
droplets have successfully prevented the two-dimensional growth of InGaAs
during crystallization under As flux supply. In the plan-view transmission
electron microscope image, the InGaAs QDs with the density of 7×109 cm-2 are
observed. These QDs show a very sharp photoluminescence peak (full width
half maximum (FWHM): 21.6 meV) at 946 nm.
Optical Poling of Phenyl-Silica Hybrid Thin Films Doped with Azo-Dye Chromophore
Authors: Kitaoka Kenji , Matsuoka Nobuaki , Si Jinhai , Mitsuyu Tsuneo , Hirao Kazuyuki
Published: October 2002

Azo-dye doped phenly group substituted silica films were prepared by a sol-gel method from
a solution of triethoxyphenlysilane (TEPh), tetraethoxysilane (TEOS) and
4-[N-ethyl-N-(2-hydroxyethyl)]amino-4′-nitro-azobenzene (DR1). The films were optically poled by the
coherent superposition of 1064 nm and 532 nm beams from a Q-switched Nd:YAG laser. Second-order susceptibility χeff of a DR1 doped phenyl group substituted film induced by the
optical poling was approximately four times as large as that of the phenyl-free film. The phenyl group in the silica
matrix was found to be effective for increasing the second-order nonlinearity and increasing
the thermal stability.
Fully Self-Aligned Organic Electroluminescent Devices with Dual Sidewall Structures
Authors: Terashita Toshiaki , Yamamoto Ichiro , Naka Shigeki , Okada Hiroyuki , Onnagawa Hiroyoshi
Published: October 2002

Fully self-aligned organic electroluminescent devices with dual sidewall structures were studied. The
principal point of the fabrication process was the formation of a sidewall structure using reactive ion etching. A
cathode metal was used as a mask for self-alignment and an insulating sidewall structure was formed around the
device periphery. The device characteristics were measured after sidewall fabrication. Emission was observed
above 3.5 V and luminance was measured to be 1000 cd/m2 at a current density of 100 mA/cm2. After the
sidewall fabrication process, wet and photolithographic processes were applied. A luminance of over 3000 cd/m2 was also observed after the final fabrication process.
Polycrystalline Silicon Thin Films Produced by Interference Laser Crystallization of Amorphous Silicon
Authors: Rezek Bohuslav , Nebel Christoph E. , Stutzmann Martin
Published: October 2002

Pulsed interference laser crystallization of amorphous silicon
has been applied to produce polycrystalline silicon thin films
with grain sizes exceeding 5 µm. It has been achieved by shifting
the samples through the interference pattern, with steps of
typical 100 nm width. Grain sizes have been investigated by atomic
force microscopy (AFM). The grains show quadratic shapes with a
typical length of the applied interference period (5 µm) and width
around 1.5–2.5 µm.
Control of Crystallization at Low Thickness in µc-Si:H Films Using Layer-by-Layer Growth Scheme
Authors: Jana Madhusudan , Das Debajyoti , Kshirsagar S. T. , Barua Asok K.
Published: October 2002

Hydrogen plasma treatment of stacking layers in a layer-by-layer (LBL)
growth scheme effectively modulates the network structure from the surface
into the bulk through the growth zone by abstraction of hydrogen from the
Si:H matrix. It is an efficient way of reducing the microcrystalline
transition layer so that virtual saturation of the crystallization may be
obtained at a significantly low thickness of the sample compared to that
obtained by a continuous mode of deposition. The growth of a highly
conducting undoped µc-Si:H film at a stacked layer thickness of ∼650 Å is
described. The film has a dark conductivity, σD, of ∼4×10-3 S·cm-1 and
exhibits a very high crystallinity, as determined by Raman scattering and
transmission electron microscope studies.
Direct Conversion of Metal Acetylacetonates and Metal Organic Acid Salts into Metal Oxides Thin Films Using Coating Photolysis Process with An ArF Excimer Laser
Authors: Tsuchiya Tetsuo , Watanabe Akio , Imai Yoji , Niino Hiroyuki , Yamaguchi Iwao , Manabe Takaaki , Kumagai Toshiya , Mizuta Susumu
Published: October 2002

Metal oxide films of TiO2, In2O3, ZrO2, ZnO, SnO2 and Fe2O3 have been successfully
prepared by the coating photolysis process using ArF excimer laser irradiation at room
temperature. When using metal acetylacetonates (acac) as the starting material, TiO2, In2O3
and ZrO2 were obtained with ArF laser irradiation at 50 mJ/cm2 at a repetition rate of
5 Hz for 5 min. When using Zn-acac, Fe, Sn, or In 2-ethylhexanoate as the starting
material, a two-step process consisting of preliminary weak and sufficiently strong
irradiation was found to be effective for obtaining ZnO, Fe2O3, SnO2 and In2O3 films.
Flattening Phenomenon Observed during Epitaxial Growth of BaTiO3 by Alternating Deposition Method
Authors: Shimoyama Kazuo , Kanda Takahiro , Iida Manabu , Maeda Tatsuro , Yamabe Kikuo
Published: October 2002

We observed a flattening phenomenon during epitaxial growth of BaTiO3 films by
alternate depositions of BaO and TiO2. When more than one monolayer (ML) of TiO2
was deposited excessively, surface smoothness degraded due to three-dimensional (3D)
growth observed by reflection high-energy electron diffraction (RHEED) and atomic
force microscope (AFM). However, subsequent BaO deposition onto the rough TiO2
surface significantly recovered the surface smoothness. It was found that a single-phase
BaTiO3 film grew by repeating the alternate deposition cycle of roughening by excessive
deposition of TiO2 and subsequent flattening by deposition of BaO.
Sensitization of the Photocurrent in C60/Merocyanine J-Aggregate Heterojunction Photovoltaic Cells
Authors: Saito Kazuhiro
Published: October 2002

C60/merocyanine J-aggregate heterojunction photovoltaic cells were
fabricated using the Langmuir-Blodgett technique to examine the
effectiveness of heterojunction formation on photoelectric conversion in the
cells. Although the J aggregate was not responsible for the
photocurrent spectrum when the C60 layer was absent, a remarkable increase and
contribution of the J aggregate in the photocurrent was observed for the
heterojunction cells. The sensitization appears to be related to energy
transfer from the excited J aggregates in the cells.
Thin Film Transistors Fabricated in Printed Silicon
Authors: Thompson Daniel Toet , Smith Patrick M. , Carey Paul G. , Sigmon Thomas W.
Published: October 2002

We report the fabrication of thin film transistors (TFTs) from printed
silicon. The printing is performed by irradiating a hydrogenated
amorphous silicon-coated quartz wafer facing a glass substrate with
a high-energy laser pulse. The ensuing explosive effusion of hydrogen
from the layer results in transfer of the silicon onto the glass substrate.
Adhesion and smoothing of the transferred film is ensured by high-energy
laser annealing. Top-gate TFTs were fabricated in this material using
standard photolithographic processing and ion implantation. These
transistors, which have reasonable electrical characteristics, are the
first step towards the fabrication of directly printed electronic devices.
Photocarrier Mobility in Regioregular Poly(3-hexylthiophene) Studied by the Time of Flight Method
Authors: S. Pandey Keiichi Kaneto , Ken Endo Ken Endo , Masahiro Rikukawa Masahiro Rikukawa
Published: October 2002

The carrier mobility in the regioregular poly(3-hexylthiophene)(PHT) film has been studied by means of the time of flight (TOF) method using a sandwich-type cell of indium tin oxide(ITO)/PHT (cast film)/Al. The response of the photocurrent exhibits a dispersive character; however, the clear kink associated with the transit time of the carrier is observed. The drift mobility of holes is determined to be 4 ×10-4 cm2/V·s and almost independent of the field > 105 V/cm at room temperature. This is the largest TOF mobility in poly(3-alkylthiophene) reported to date. It is also found that the activation energy of the mobility is 88 meV and almost independent of the field. The results are discussed taking various transport models into consideration.
Influence of Ostwald Ripening of End-of-Range Defects on Transient Enhanced Diffusion in Silicon
Authors: Uematsu Masashi
Published: October 2002

We have simulated transient enhanced diffusion (TED) in the presence of end-of-range (EOR)
defects produced by amorphizing implantation. We have taken into account Ostwald ripening of
EOR defects, which reduces the efficiency of the defects as a source of self-interstitials.
We derived a formula to describe this reduction of efficiency with time and used this formula
for the simulation. The simulation satisfactorily predicts the TED at annealing conditions,
where the influence of Ostwald ripening is significant.
Diamagnetic Property Observed in Langmuir-Blodgett Heterofilm
Authors: Hino Taro
Published: October 2002

The Al/Langmuir-Blodgett (LB) heterofilm/Au structure was deposited on a silicon wafer substrate with SiO2 film. The LB heterofilm was composed of the arachidic acid LB film (nonpolar)
and the tetracyanoquinodimethane (TCNQ) compound LB film (polar).
A repulsive force indicating the diamagnetic property of the LB
heterofilm was observed under a magnetic field at room temperature. The repulsive force was measured using an apparatus which
can measure a displacement such as small as 10-2 µm by a laser
displacement meter.
Time-of-Flight Measurement of Hole Mobility in Aluminum (III) Complexes
Authors: Shigeki Naka Shigeki Naka , Hiroyuki Okada Hiroyuki Okada , Hiroyoshi Onnagawa Hiroyoshi Onnagawa , Junji Kido Junji Kido , Tetsuo Tsutsui Tetsuo Tsutsui
Published: October 2002

We measured hole drift mobility in vacuum-deposited films of aluminum (III) complexes,
tris (8-quinolinolato) aluminum (III) (Alq3),
tris (8-phenanthridinolato) aluminum (III) (Alph3) and
tris (4-methyl-8-quinolinolato) aluminum (III) (Almq3),
using a time-of-flight technique.
Hole transport was nondispersive for Alq3 and
dispersive for Alph3 and Almq3.
The hole mobilities of these aluminum complexes
were of the order of 10-10–10-8 cm2/V·s and
were largely dependent on the electric field.
Functionalized Mesogenic Composite for Photorefractive Applications
Authors: Kawamura Hiroshi Ono Tomomi , Kawatsuki Nobuhiro , Norisada Hideki , Yamamoto Tohei
Published: October 2002

A mesogenic composite, which consists of a functionalized copolymer, low-molar-mass liquid crystals (L-LCs) and a sensitizing dye, was developed for photorefractive applications. The polymer dissolved L-LC composite (PDLCC) exhibited a mesophase although the copolymer itself did not exhibit a LC phase. A high gain coefficient of over 200 cm-1 was achieved with low applied dc fields (0.34 V/µm).
Hydrogen Reduction Properties of RuO 2 Electrodes
Authors: Hiratani Masahiko , Matsui Yuichi , Imagawa Kazushige , Kimura Shinichiro
Published: October 2002

The thermodynamic stability of RuO2 under a reducing atmosphere
containing hydrogen gas was investigated. The RuO2 electrode is reduced to Ru
metal at 200°C in 0.3% H2 and at 300°C in 0.03% H2, even when the electrode is
stacked with a (Ba, Sr)TiO3 dielectric layer. The reduction decreases the
electrode volume. Our findings indicate that application of the RuO2 electrode in
device integration will be difficult because of the thermodynamic instability as
long as the thermal equilibrium state of reduction is attained during hydrogen
sintering.
Resonant Tunneling Chaos Generator for High-Speed/Low-Power Frequency Divider
Authors: Yoichi Kawano Yoichi Kawano , Shigeru Kishimoto Shigeru Kishimoto , Koichi Maezawa Koichi Maezawa , Takashi Mizutani Takashi Mizutani
Published: October 2002

We propose a chaos generator using a resonant tunneling diode.
It is a simple circuit consisting of a resonant tunneling diode, an inductor, and a capacitor.
This circuit is found to output various kinds of signal patterns including chaos.
The behavior of the circuit is studied by means of a bifurcation diagram.
Though the chaos has several applications, we describe here the possibility
of implementing a high-speed and low-power frequency divider in the bifurcation region.
The operating principle is also confirmed using discrete devices.
Strong Carrier Localization in GaInN/GaN Quantum Dots Grown by Molecular Beam Epitaxy
Authors: Damilano Benjamin , Vezian Stéphane , Grandjean Nicolas , Massies Jean
Published: October 2002

GaInN/GaN quantum dots (QDs) are grown by molecular beam epitaxy making use of the Stranski-Krastanov growth regime.In situscanning tunneling microscopy (STM) evidences the formation of three-dimensional GaInN islands. An island density as high as 1012cm-2is deduced from STM images. It is shown that the room-temperature photoluminescence (PL) of GaInN/GaN QDs can be tuned from 3 eV to 2.5 eV by increasing the GaInN thickness from 10 to 30 Å. Photothermal deflection spectroscopy is carried out to measure the absorption of GaInN/GaN QDs. For dots emitting at 2.63 eV, a Stokes shift of 250 meV is found between the maximum PL energy and the absorption edge indicating very strong carrier localization.
Time-Resolved Emission from Self-Assembled Single Quantum Dots Using Scanning Near-Field Optical Microscope
Authors: Madoka Ono Madoka Ono , Kazunari Matsuda Kazunari Matsuda , Toshiharu Saiki Toshiharu Saiki , Kenichi Nishi Kenichi Nishi , Takashi Mukaiyama Takashi Mukaiyama , Makoto Kuwata-Gonokami Makoto Kuwata-Gonokami
Published: October 2002

We study time-resolved emission from self-assembled single InGaAs/GaAs
quantum dots by the time-correlated single photon counting method using
near-field optical microscopy.
The decay time of the emission from discrete levels of a single quantum
dot increases with the decrease in the emission energy and with the
increase in the excitation intensity.
We develop a rate equation model which accounts for the initial
filling of the states, cascade relaxation, state filling and carrier
feeding from a wetting layer.
High collection efficiency of a double-tapered-type fiber probe enables
us to study the emission even at very weak excitation intensities. The direct
excitation into a single dot is dominant at this excitation
level. State filling, cascade relaxation and extra carrier feeding
from the wetting layer become pronounced when the excitation intensity
increases.
Spatial Distribution Measurement of Absolute Densities of CF and CF 2 Radicals in a High Density Plasma Reactor Using a Combination of Single-Path Infrared Diode Laser Absorption Spectroscopy and Laser-Induced Fluorescence Technique
Authors: Masayuki Nakamura Masayuki Nakamura , Hirotaka Nakayama Hirotaka Nakayama , Masafumi Ito Masafumi Ito , Masaru Hori Masaru Hori , Toshio Goto Toshio Goto , Akihiro Kono Akihiro Kono , Nobuo Ishii Nobuo Ishii
Published: October 2002

We have developed a measurement method for obtaining spatial
distributions of absolute densities of CF and CF2 radicals in a plasma
reactor by combining single-path infrared laser absorption spectroscopy
(IRLAS) and laser-induced fluorescence (LIF) techniques. This novel method
has been successfully applied to the spatial distribution measurement
of absolute densities of CF and CF2 radicals in an electron cyclotron
resonance (ECR) plasma reactor employing a tetrafluorocarbon gas
(C4F8). It was found that CF radical densities were higher
than CF2 ones in the plasma region but lower outside the plasma region.
Tunable Optical Stop Band Utilizing Thermochromism of Synthetic Opal Infiltrated with Conducting Polymer
Authors: Shigenori Satoh Shigenori Satoh , Hirotake Kajii Hirotake Kajii , Yoshiaki Kawagishi Yoshiaki Kawagishi , Akihiko Fujii Akihiko Fujii , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Conducting polymers can be infiltrated into a nanoscale interconnected regular array of voids in synthetic opal in the liquid state upon heating. Optical properties such as transmission and reflection spectra of the synthetic opal infiltrated with conducting polymer poly(3-alkylthiophene) have been found to change drastically with temperature. The control of the stop band by utilizing the change of the refractive index associated with the thermochromism of synthetic opal infiltrated with conducting polymer is proposed as an example of a tunable photonic crystal.
Role of Electron Thermal Motion in Evanescent Electromagnetic Wave Structure of Inductively Coupled Plasma
Authors: Seiji Takechi Seiji Takechi , Shunjiro Shinohara Shunjiro Shinohara
Published: October 2002

The role of electron thermal motion in radio-frequency (RF) plasma produced by a planar, spiral antenna was examined. The measured evanescent wave amplitude and the phase were compared to the calculated results obtained from a one-dimensional collisionless (nonlocal) model, changing the boundary condition, Ar filling pressure and RF frequency. It was demonstrated that electron thermal motion plays a more important role under the condition of low collisionality.
Measurements of Piezoelectric Coefficient of Pb(Zr, Ti)O3 Thin Film Using a Piezoelectric Microcantilever
Authors: Chu Jiaru , Wang Zhanjie , Maeda Ryutaro
Published: October 2002

A piezoelectric cantilever is used to measure the magnitude of
the effective longitudinal piezoelectric coefficient (d
33) of
piezoelectric thin film. The cantilever is excited to its resonance
frequency by the application of an ac voltage to its piezoelectric
layer, and its tip is in cyclic contact with the top electrode of
the sample. The surface motion of the sample due to the applied bias
voltage is measured through monitoring the variations of the
cantilever vibration amplitude, which are proportional to the
piezoelectric current travelling though the cantilever. The d
33 of a
sol-gel-derived on lead zircornate titanate (PZT) film is measured
as 0.9 Å/V.
Growth and Characterization of the Isotopically Enriched 28Si Bulk Single Crystal
Authors: M. Itoh Ken-ichiro Takyu , I. Ozhogin Kunihiko Oka
Published: October 2002

We report on the successful growth of an isotopically enriched
28Si bulk single crystal of the size ∼4 mm in diameter and
∼50 mm in length. The isotopic enrichement of
28Si (99.924 at%), 29Si (0.073 at%), and
30Si (0.003 at%)
has been determined by secondary-ion-mass spectroscopy (SIMS).
The crystal is entirely p-type with the room temperature
free-hole concentration ∼ 5×1017 cm-3.
The majority impurity is found to be aluminum which
can be removed easily in the future
zone purification process.
Diels-Alder Reaction on the Clean Diamond (100) 2×1 Surface
Authors: Hossain Md. Zakir , Aruga Tetsuya , Takagi Noriaki , Tsuno Takashi , Fujimori Naoji , Ando Toshihiro , Nishijima Mitsuaki
Published: October 2002

The interaction of 1,3-butadiene with the C(100)2×1 surface at 300 K has been studied
by electron energy loss spectroscopy (EELS) and low-energy electron diffraction (LEED).
EELS studies show that 1,3-butadiene readily chemisorbs on the C(100)2×1 surface by the
Diels-Alder reaction ([4+2] cycloaddition) where the surface dimer act as a dienophile.
The surface product is found to be stable up to ∼1000 K. Orbital symmetry of the
reacting species is an important factor in the reaction of unsaturated hydrocarbons with
the C(100)2×1 surface.
Improved Electrical Characteristics of Al 2O 3/InP Structure by Combination of Sulfur Passivation and Forming Gas Annealing
Authors: Shinya Morikita Shinya Morikita , Tomoyuki Motegi Tomoyuki Motegi , Hideaki Ikoma Hideaki Ikoma
Published: October 2002

The capacitance-voltage (C–V) characteristics of a Al2O3/InP capacitor fabricated by helicon-wave excited
O2–Ar plasma oxidation of vacuum–evaporated Al were significantly improved by a combination of sulfur passivation of the InP substrate in (NH4)2Sx (for 60 min) and post-thermal annealing in forming gas (FG) containing 5% H2 (at 350°C) of the grown films after plasma oxidation. X-ray photoelectron spectroscopic (XPS) data indicated the formation of In–S bonds and suppression of InP oxidation after the sulfur passivation. The reason for the improved C–V characteristics is briefly discussed as being due to the termination of the incomplete or dangling bonds by sulfur and hydrogen.
Strategy for Off-Current Suppression in Thin-Film Transistors
Authors: Müller Heinz-Olaf , Alphenaar Bruce W.
Published: October 2002

Field induced trap assisted band-to-band tunneling in poly-silicon thin-film transistors
is studied using a two-dimensional model. Both the space dependence and the effect of
graded doping are investigated. A graded doping profile results in a moderate reduction
in the current, while a much larger reduction is achieved by increasing the thickness of the
gate oxide near the drain region. In this way, the on/off ratio of the thin-film transistor
should be greatly improved.
Dynamic Force Microscopy Investigations of C60 Deposited on Si(111) Surface
Authors: Kei Kobayashi Kei Kobayashi , Hirofumi Yamada Hirofumi Yamada , Toshihisa Horiuchi Toshihisa Horiuchi , Kazumi Matsushige Kazumi Matsushige
Published: October 2002

Dynamic force microscopy (DFM) was applied for investigating on the structures of C60 multilayer thin films deposited on the Si(111)-7 ×7 reconstructed surface. C60 molecules on the crystalline island have been successfully imaged with a molecular resolution for the first time in an ultrahigh vacuum environment. In addition, a difference in the contrast of phase image between the islands and the monolayer-covered Si surface was observed.
Room-Temperature Bonding of Si Wafers to Pt Films on SiO2 or LiNbO3 Substrates Using Ar-Beam Surface Activation
Authors: Takagi Hideki , Maeda Ryutaro , Hosoda Naoe , Suga Tadatomo
Published: October 2002

We have developed a method to bond Si wafers to Pt films on SiO2
or LiNbO3 substrates at room temperature. Ar beam etching is used to
remove contaminants from the surfaces of the Si wafers and the Pt
films, and the surfaces become activated. Strong bonding between Si
and Pt is achieved without any heat treatment. Low-temperature
chemical reaction between Si and Pt is assumed to play a role in the
bonding process. This method enables the integration of diverse
materials. Many applications of Pt film buried between two wafers are
also expected.
High-Performance Fiber-Optic Fabry-Perot Pressure Sensor with Si3N4/SiO2/Si3N4 Diaphragm
Authors: Park Jaehee , Kim Myung-Gyoo
Published: October 2002

The high-performance fiber optic Fabry-Perot pressure sensor with a
Si3N4/SiO2/Si3N4
(N/O/N) diaphragm fabricated using micromachining technology in
anisotropic etchant KOH solution was developed. The configuration of this sensor was a
2-cm-long fiber optic Fabry-Perot interferometer bonded to a 0.6-µm-thick diaphragm.
When the area of the N/O/N diaphragm used in the experiments was 2×2 mm2, the
pressure sensitivity was 0.11 radian/kPa, and when the area was 8×8 mm2, the pressure
sensitivity was 1.57 radian/kPa. The relationship between the applied pressure and the
phase change was linear.
A Simple Method to Analyze the Electrical Properties of High Power Lateral Double-Diffused Metal-Oxide-Semiconductor Transistors
Authors: Tsung-Yi Huang Tsung-Yi Huang , Jeng Gong Jeng Gong
Published: October 2002

In this paper a new approach of obtaining the electrical properties of the
power lateral double-diffused metal-oxide-semiconductor field-effect
transistors (LDMOSFET) is proposed. The device is regarded as a junction
field-effect transistor (JFET), the N-well region, in series with an active
metal-oxide-semiconductor field-effect transistors (MOSFET). The I-V
relation of these two parasitic FETs were first separately obtained from
actual device structure and then combined together to generate the I-V
relation for the power MOSFET. This model also explains why the
transconductance has a maximum value at mediate gate voltage and decreases
drastically with higher gate voltages. The simulation program, MEDICI,
verifies the accuracy of this analytical method. Since the model contains
only two parasitic devices, it affords a fast and easy method to analyze the
I-V characteristic of power MOSFET.
Ion Energy Distribution in Alternating-Current Plasma Display Panel Cell
Authors: Young Kyo Shin Young Kyo Shin , Jae Koo Lee Jae Koo Lee , Chae Hwa Shon Chae Hwa Shon , Woong Kim Woong Kim
Published: October 2002

In an alternating-current plasma display panel cell,
elastic collisions between the neutral gas and ions
keep most ion energies much lower than the applied voltage.
Two-dimensional kinetic simulation reveals that
the majority (90%) of the plasma ions impinging on the dielectric layer
have energy at or below 10% of the applied voltage of 250 V calling for
the need for measurement of the secondary electron emission-coefficient
below 50 eV.
The kinetic potential and density profiles compare well with
those of a two-dimensional fluid simulation.
Room-Temperature Continuous-Wave Operation of InGaN Multi-Quantum-Well Laser Diodes Grown on an n-GaN Substrate with a Backside n-Contact
Authors: Kuramoto Masaru , Sasaoka Chiaki , Hisanaga Yukihiro , Kimura Akitaka , Yamaguchi A. Atsushi , Sunakawa Haruo , Kuroda Naotaka , Nido Masaaki , Usui Akira , Mizuta Masashi
Published: October 2002

Continuous-wave operation at room-temperature has been demonstrated for
InGaN multi-quantum-well (MQW) laser diodes (LDs) grown on
low-dislocation-density n-GaN substrates with a backside n-contact. The
current, current density and voltage at the lasing threshold were 144 mA,
10.9 kA/cm2 and 10.5 V, respectively, for a 3 µm wide ridge-geometry diode
with high-reflection dielectric coated mirrors. Single-transverse-mode
emission was observed in the far-field pattern of the LDs and the beam full
width at half power in the parallel and perpendicular directions was 6° and
25°, respectively.
Preparation of SrBi2Ta2O9 Thin Films by Metalorganic Chemical Vapor Deposition from Two New Liquid Organometallic Sources
Authors: Funakubo Hiroshi , Nukaga Norimasa , Ishikawa Katsuyuki , Watanabe Takayuki
Published: October 2002

SrBi2Ta2O9 thin films were prepared with high compositional reproducibility by
metalorganic chemical vapor deposition (MOCVD) using Bi(CH3)3, Sr[Ta(O·C2H5)6]2 and O2
as source materials. When the deposition temperature was increased, the Bi/Ta and Sr/Ta
ratios in the film increased and decreased, respectively. This behavior can be estimated from
the deposition temperature dependence of Bi2O3 and Sr–Ta–O films deposited from Bi(CH3)3–O2
and Sr[Ta(O·C2H5)6]2–O2 systems, respectively. Bi/Ta ratio can be controlled by the
input gas concentration ratio of Bi(CH3)3 to Sr[Ta(O·C2H5)6]2 at 600°C. On the other hand,
Sr/Ta ratio was independent of the input gas concentration. An almost single phase of
SrBi2Ta2O9 was deposited at 670°C. The remanent polarization and the coercive field of the
film deposited at 670°C following heat treatment at 750°C for 30 min in O2 atmosphere were
5.0 µC/cm2 and 80 kV/cm, respectively.
Growth of Epitaxial Silicon Film at Low Temperature by Using Sputtering-Type Electron Cyclotron Resonance Plasma
Authors: Gao Junsi , Nakashima Hiroshi , Sakai Naofumi , Gao Dawei , Wang Junli , Furukawa Katsuhiko , Muraoka Katsunori
Published: October 2002

A novel method for growth of epitaxial silicon films on Si substrates at a low temperature of
400°C has been developed using a sputtering-type electron cyclotron resonance plasma. The
chamber has a base pressure of 5×10-7 Torr, and the growth method includes in situ cleaning of
Si substrates using suitable plasma bombardment and subsequent deposition at a high sputter
rate to prevent impurity monolayer formation at the beginning of the deposition. The epitaxial
growth conditions were investigated using spectroscopic ellipsometry and electron backscattering
diffraction, and the effect of the Ar gas flow rate, for both the in situ cleaning and the
deposition conditions, was studied. At the optimum growth conditions, Si thin films having
characteristics close to crystal Si substrates were obtained. The deposition rate was as high as
6 nm/min.
Advantage of Shallow Trench Isolation over Local Oxidation of Silicon on Alignment Tolerance
Authors: Shiozawa Katsuomi , Oishi Toshiyuki , Sugihara Kohei , Furukawa Akihiko , Abe Yuji , Tokuda Yasunori
Published: October 2002

We investigate the differences between the breakdown characteristics against contact hole
etching for shallow trench isolation (STI) and the local oxidation of silicon (LOCOS). Although the
breakdown voltage of STI varied negligibly despite the large contact overlap, the isolation
characteristics of the LOCOS were drastically degraded due to the slight overlapping with the
contact hole. The cross-sectional scanning electron microscope observations revealed that the
considerable difference between STI and the LOCOS is closely related to the field oxide shapes
modified by contact hole etching. We concluded that STI, in which the original field oxide abruptly
projects above the substrate surface, has an advantage over the LOCOS not only against isolation
space reduction but also alignment tolerance reduction.
Characterization of GaAs Surfaces Treated with Remote PH3 Plasma
Authors: Nozu Satoshi , Matsuda Koichiro , Sugino Takashi
Published: October 2002

Surface passivation of GaAs by remote PH3 plasma treatment has been attempted. PH3
plasma treatment leads to the removal of As oxides and phosphidization of GaAs surfaces.
The generation of As oxide is suppressed at the surface of phosphidized GaAs. Schottky
junctions are formed on the GaAs surface after phosphidization. A metal work function
dependence of the barrier height is found for Schottky junctions on phosphidized GaAs
under optimum conditions, suggesting that phosphidization is effective in reducing the
surface state density of GaAs.
Study of the Crystallization of GeSbTe Films by Raman Spectroscopy
Authors: Tominaga Junji , Atoda Nobufumi
Published: October 2002

We have investigated the Raman spectra of thermally and laser annealed Ge2Sb2Te5 films.
The thermally crystallized film included few amorphous Te–Te bonds, however a large number
of the Te–Te bonds remained in the laser annealed film. It was suggested that the Te–Te
amorphous bonds were one of the main reasons leading to the erasability during the first few
cycles of overwriting.
High-Power Microwave-Induced Helium Plasma at Atmospheric Pressure for Determination of Halogens in Aqueous Solution
Authors: Okamoto Yukio
Published: October 2002

A high-power (∼1000 W CW, 2.45 GHz) annular-shaped microwave-induced helium
plasma was developed for determination of halogens in the aqueous solutions, and the
preliminary characteristics are presented. The plasma was generated at atmospheric
pressure by an Okamoto cavity which was modified to focus the energy. No external
cooling was used to stabilize the plasma. An aqueous solution was injected into the plasma
by an ultrasonic system with desolvation and condensation. The electron density and iron-excitation
temperature were on the order of 1014/cm3 and 5000 K, respectively. Introduction of
aqueous chloride in the form of NaCl and bromide in the form of KBr produced intense ion
emission and detection limits of 0.1 ppm (µg/ml) for Cl II (479.5 nm) and 0.2 ppm (µg/ml)
for Br II (470.5 nm) were obtained.
Anisotropic Waves Propagating on Two-Dimensional Arrays of Belousov-Zhabotinsky Oscillators
Authors: Kenji Suzuki Kenji Suzuki , Tatsuo Yoshinobu Tatsuo Yoshinobu , Hiroshi Iwasaki Hiroshi Iwasaki
Published: October 2002

A new photolithographic method was developed to enable precise patterning of a catalyst on a cation-exchange membrane. A large number of catalyst (ferroin) dots were arranged on triangular and square lattices to study pattern formation on a two-dimensional array of Belousov-Zhabotinsky (BZ) oscillators. When the distances among the dots were adjusted properly, the propagation of anisotropic chemical waves was experimentally observed in the discrete BZ reaction systems.
Strained YBa2Fe3O8-δ Films Lattice-Matched to YBa2Cu3O7-δ
Authors: Usagawa Toshiyuki , Unoki Hiromi , Terasaki Ichiro , Wen Jianguo , Koshizuka Naoki , Enomoto Youichi
Published: October 2002

We report on the first successful growth of c-axis oriented isomorphic insulator films to YBa2Cu3O7-δ (YBCO), YBa2Fe3O8-δ (YBFO) films on (001) MgO substrates by the same growth conditions with YBCO films. The YBFO film shows a sufficiently high insulating resistivity of 1.2×109 Ωcm at 80 K for various applications of 123 oxide superconductors to electronics. The obtained c-axis lattice constants by θ-2θ X-ray diffraction measurements are typically 11.911 Å. The YBFO film grown on homoepitaxial (110) YBCO films shows the 123 structure at the initial stage of growth. However, the thicker part of the YBFO film is found to have the 123 cubic structure of (Y1/3Ba2/3)3Fe3O8-δ by Transmission Electron Microscopy (TEM) observation.
Determination of the Electrooptic and Piezoelectric Coefficients of the Molecular Nonlinear Optical Crystal 2-furyl methacrylic anhydride
Authors: Kerkoc Primoz , Maruo Seiji , Horinouchi Suguru , Sasaki Keisuke
Published: October 2002

Accurate measurements of the electrooptic and piezoelectric coefficients of 2-furyl methacrylic anhydride (FMA) single crystals were performed. The low modulation
frequency electrooptic coefficients at the wavelength of 632.8 nm are: r
33=7.1±0.4 pm/V and r
13=4.5±0.2 pm/V, whereas the inverse piezoelectric coefficients are: d
33=8.2±0.4 pm/V and d
13=2.2±0.1 pm/V.
Evaluation of (Pb, La)(Zr, Ti)O3 (PLZT) Capacitors of Different Film Thicknesses with Pt/SrRuO3 Top Electrodes
Authors: Cross Jeffrey S. , Fujiki Mitsushi , Tsukada Mineharu , Matsuura Katsuyoshi , Otani Seigen
Published: October 2002

(Pb, La)(Zr, Ti)O3 [PLZT] films with thicknesses of 150, 225 and 300 nm were prepared by
chemical solution deposition (CSD) on Pt/IrO2 coated SiO2/Si wafers. Top electrodes of
Pt/SRO were sputter deposited and annealed at 600°C to form a capacitor. All three PLZT
films were highly (111) oriented and showed high switchable polarization of >40 µC·cm-2
at 200 kV·cm-1. A coercive field of 40 kV·cm-1 was observed for all three films regardless
of thickness. Little fatigue degradation was observed up to 1010 cycles. These results
indicate that it is possible to combine both oxide and metallic contacts in a high endurance
ferroelectric capacitor for low voltage applications.
Emission of Short Microwave Pulse Radiated by Interaction between Periodic Static Electric Field and Relativistic Ionization Front
Authors: Takeshi Higashiguchi Takeshi Higashiguchi , Noboru Yugami Noboru Yugami , Hiroshi Okabe Hiroshi Okabe , Toshihiko Niiyama Toshihiko Niiyama , Eiji Takahashi Eiji Takahashi , Hiroaki Ito Hiroaki Ito , Yasushi Nishida Yasushi Nishida
Published: October 2002

Experimental results on “DARC (DC to AC radiation converter)”
using 4 ω0 light of a Nd:YAG laser with a pulse duration of ∼6 ns
are reported. Electromagnetic wave generation has been observed in the
interaction experiments between a static electric field and a
relativistic ionization front.
The frequency of the emitted microwave pulse (∼
6 ns) ranges from 9.5 GHz to 14.1 GHz.
The output signal intensity is proportional to the DC bias voltage
with a power of 2.3.
The emitted radiation field is polarized along the static electric
field direction.
The pulse duration of the emitted radiation is as long
as that of the ionizing laser. This indicates that the pulse duration
strongly depends on the ionization process by the laser light.
Preparation of (Ba, Sr)TiO3 Thin Films with High Pyroelectric Coefficients at Ambient Temperatures
Authors: Lee Jae Shin , Park Jae-Seok , Kim Jin-Sup , Lee Jung-Hee , Lee Yong Hyun , Hahn Suk-Ryong
Published: October 2002

Ferroelectric barium strontium titanate (BST) thin films were grown on Pt/Ta2O5/SiO2/Si
by sputtering Ba0.66Sr0.34TiO3 targets containing different amounts of excess SrO. It was found
that the excess SrO in the target strongly influenced the microstructures and pyroelectric
properties of the BST films. Compared with the BST film grown using a target without excess
SrO, BST films grown using targets containing excess SrO of 0.02–0.04 by molar fraction
showed larger grains and higher tendency to grow along (200) orientation, resulting in better
pyroelectric characteristics at ambient temperatures. We obtained BST films with a
considerably high pyroelectric coefficient of 240 nC·cm-2·K-1.
Combinatorial Laser Molecular Beam Epitaxy (MBE) Growth of Mg–Zn–O Alloy for Band Gap Engineering
Authors: Matsumoto Yuji , Murakami Makoto , Jin Zhengwu , Ohtomo Akira , Lippmaa Mikk , Kawasaki M. , Koinuma Hideomi
Published: October 2002

We have developed a new combinatorial synthesis system integrating a combinatorial shadow mask into a laser MBE (molecular beam epitaxy) chamber. This combinatorial Laser MBE system can be used for fabricating a number of crystalline films with different compositions on a substrate under programmed temperature and pressure conditions. The method was applied to alloying and band gap engineering of ZnO by positional substitution of Mg into ZnO thin films. The superiority of the combinatorial methodology to conventional one-by-one synthesis is evident from the high linearity of thec-axis length and band gap dependence on Mg content.
Synthesis of Epitaxial TiO2 Thin Films on MgO(100) Using a Combination of an Oxygen-Radical Beam and a Tetra-isopropoxy Titanium Molecular Beam
Authors: Watanabe Shigeyuki , Katsura Kazumasa , Nozoye Hisakazu
Published: October 2002

We synthesized epitaxial titanium oxide thin films on MgO (100)
using a combination of a metalorganic pulsed molecular beam and
an oxygen-radical beam. At temperatures below 350°C, titanium oxide (TiO2)
thin films were exclusively deposited only when an oxygen-radical
beam was irradiated along with Ti(i-OC3H7)4. Above this temperature, TiO2
thin films were deposited both in the presence and absence of the
oxygen-radical beam; however, the oxygen-radical beam enhanced the
deposition rate as well as the crystallinity of the titanium oxide thin films.
Sputter Deposition of Cerium Yttrium Iron Garnet Films on Substrates with Ion-Beam Bombarded Patterns
Authors: Yasuyuki Okamura Yasuyuki Okamura , Sadahiko Yamamoto Sadahiko Yamamoto
Published: October 2002

We report the experimental results of magnetooptic rare-earth iron-garnet sputtered film deposition on substrates with a modified surface. The magnetooptic garnet considered here is cerium-substituted yttrium iron garnet which is one of the promising materials for nonreciprocal optical devices and magnetooptic recording media. The surface of the substrate, gadolinium gallium garnet, is etched by ion-beam bombardment, whose energy was controllable from 0.2 keV to 1 keV. By varying the ion-beam energy, the deposited films can be in either the crystalline or the amorphous state and the quality of grown crystalline films can be improved. The results obtained are explained in terms of the surface morphology of substrates.