bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix-Dependent Percolation and Resistivity versus Temperature Behaviors of Conducting Composite Thin Films
Authors: Hirano Shingo , Kishimoto Akira
Published: October 2002

The surface resistivity of crosslinked polymer matrix conductive ceramic filler composite thin
films was studied as a function of composition and temperature. Epoxy resin and
unsaturated polyester resin were selected as the insulating matrices. The resistivities of both
thin films showed a percolative conduction, and the critical percolation threshold values of the
filler weight fraction depended on the type of insulating polymer. The epoxy composite
film exhibited a pronounced positive-temperature-coefficient-of-resistivity (PTCR) effect
above the glass transition temperature of the matrix. In contrast, the unsaturated polyester
composite did not show such an effect. To examine the nature of the percolation and the
resistivity versus temperature behavior, the adhesive strength measurements and
thermomechanical analysis were conducted on the matrix polymers. The results suggest that
the percolation behavior and the occurrence of the PTCR effect in conductor-filled
crosslinked polymer composites can be more precisely calculated by taking into account the
thermomechanical interaction factor of the components.
Stereoscopic Display Based on a Volume Holographic Storage
Authors: Lee Seung-Hyun , Kim Eun-Soo
Published: October 2002

We present a stereoscopic display system using a volume hologram. The stereoscopic image
pairs are recorded into a volume holographic memory with a reference beam. Multiple
stereoscopic image pair holograms within common volume is possible using angular multiplexing.
The reference beam with Bragg matching condition is scattered by the index grating and the
diffracted beams are propagating along the directions of the stereoscopic image pairs. The images
are to be suitably projected on the left and right display plane for stereoscopic viewing.
Highly Reliable, Backside Emissivity Independent Cobalt Silicide Process Using a Susceptor-Based Low Pressure Rapid Thermal Processing System
Authors: Yoo Woo Sik , Atanos Ashur J. , Whitworth David M.
Published: October 2002

Very thin cobalt silicide formation and annealing processes were investigated as a function
of process temperature (350–700°C) and Co film thickness using a susceptor-based low
pressure rapid thermal processing (RTP) system. TiN capped thin Co films were
investigated. Highly reliable, backside emissivity independent, low resistance, production
worthy shallow silicide contact formation process has been demonstrated. Both a wide
process window and an excellent sheet resistance uniformity have been demonstrated in
cobalt silicide process integration steps. The net added non-uniformity of typical TiN
capped 10 nm thick cobalt films was less than 0.5%.
Electrical Properties of Al/CaF2/i-Diamond Metal-Insulator-Semiconductor Field-Effect-Transistor Fabricated by Ultrahigh Vacuum Process
Authors: Yun Young , Maki Tetsuro , Tanaka Hiroyuki , Shirakawa Yusuke , Kobayashi Takeshi
Published: October 2002

In order to avoid oxygen contamination on the diamond surface as far as possible
during the device process, the diamond metal-insulator-semiconductor field-effect
transistor (MISFET) was prepared by a reduced-oxygen process including an ultrahigh
vacuum (UHV) process for the first time, and its electrical properties were investigated
in detail. According to the results, it was found that the electrical properties of the
MISFET were improved to a great extent in comparison with those of conventional
diamond MISFETs. The observed effective mobility (µeff) was 400 cm2/V·s at room
temperature, which is the highest value obtained until now in the diamond FET at
room temperature. Besides, the measured transconductance (g
m) and surface state
density (N
SS) of the device operation region was 5 mS/mm and ∼1010/cm2·eV,
respectively, which is also comparable with conventional Si metal-oxide-semiconductor
field-effect-transistors (MOSFETs) with the same gate length (L
g = 30 µm).
Visualization of Optically Controlled Magnetic Flux in YBa 2Cu 3O 7-δ Thin Film Loop by Terahertz Radiation Imaging
Authors: Masayoshi Tonouchi Masayoshi Tonouchi , Shin-ichi Shikii Shin-ichi Shikii , Masatsugu Yamashita Masatsugu Yamashita , Kazuo Shikita Kazuo Shikita , Takashi Kondo Takashi Kondo , Osamu Morikawa Osamu Morikawa , Masanori Hangyo Masanori Hangyo
Published: October 2002

Magnetic flux generated optically in YBa2Cu3O7-δ thin film loops was visualized by means of terahertz (THz) radiation imaging.
By scanning the laser spot on the sample surface, we obtained a two-dimensional radiation pattern that represents supercurrent distribution.
The observed images revealed that the fs laser pulse can create magnetic flux in the superconductive loops and also control the polarity of the flux.
We discuss the relationship between the supercurrent distribution and the optically generated magnetic flux in the loop.
Photo-Dimerized Monolayer (PDML) versus Rubbed Polyimide (RPI): A Comparison of Electro-Optic Properties
Authors: Shenoy Devanand , Grüeneberg Kirsten , Naciri Jawad , Shashidhar Ranganathan
Published: October 2002

Electro-Optic response characteristics as well as polar anchoring energies of liquid crystal
cells prepared using a new photo-alignment technique i.e., photo-dimerized monolayer,
have been measured. These data are compared with those for cells that use a rubbed
polyimide alignment layer. The two alignment methods yield comparable electro-optic
properties showing thereby that the new photo-alignment technique is a viable alternative
to the rubbed alignment technique for display applications.
Morphology Control of Cu Clusters Formed on H-Si(111) Surface in Solution by Si Potential
Authors: Ken-ichi Hara Ken-ichi Hara , Iwao Ohdomari Iwao Ohdomari
Published: October 2002

We have controlled the morphology of Cu clusters formed on H-terminated Si(111) surface in solution by controlling Si potential. At a Si potential of -0.70 eV vs SHE, Cu wires of 50 nm width were formed along a ridge composed of dihydride Si atoms at the intersections of steps equivalent to
[11\overline2]. In contrast, no Cu morphology was observed along a
ravine composed of monohydride Si atoms.
Current and Temperature Dependences of Electroluminescence of InGaN-Based UV/Blue/Green Light-Emitting Diodes
Authors: Mukai Takashi , Yamada Motokazu , Nakamura Shuji
Published: October 2002

Current and temperature dependences of the electroluminescence of InGaN
UV/blue/green single-quantum-well (SQW)-structure light-emitting diodes (LEDs)
were studied. The emission mechanism of InGaN SQW-structure LEDs with emission
peak wavelengths longer than 375 nm is dominated by carrier recombination at large
localized energy states caused by In composition fluctuation in the InGaN well layer.
When the emission peak wavelength becomes shorter than 375 nm, the conventional
band-to-band emission mechanism becomes dominant due to poor carrier localization
resulting from small In composition fluctuations. In addition, the quantum-confined
Stark effect due to the piezoelectric field becomes dominant, which causes a low output
power of the UV LEDs.
Room-Temperature Continuous Wave Operation of InGaN Laser Diodes with Vertical Conducting Structure on SiC Substrate
Authors: Kuramata Akito , Kubota Shin-ichi , Soejima Reiko , Domen Kay , Horino Kazuhiko , Tanahashi Toshiyuki
Published: October 2002

We demonstrated for the first time room-temperature continuous wave operation of
InGaN laser diodes with a vertical conducting structure fabricated on a SiC substrate.
The threshold current and voltage were 84 mA and 12 V, respectiely, under pulsed
operation. The threshold current corresponds to a threshold current density of 5.6 kA/cm2,
which is the lowest ever reported with InGaN laser diodes on a SiC substrate.
Under continuous wave operation, the threshold current and voltage were 115 mA and
10.5 V, respectiely. The peak lasing wavelength was 408.2 nm. Longitudinal modes
of the optical cavity were clearly obsered. The laser oscillation was obsered up to
40°C under CW operation.
Ultrashallow p+/n Junction Formation by 0.5–1 keV Ion Implantation
Authors: Jihwan Park Jihwan Park , Jeong-Youb Lee Jeong-Youb Lee , Kilho Lee Kilho Lee , Hyunsang Hwang Hyunsang Hwang
Published: October 2002

We have evaluated the electrical characteristics and the secondary ion mass
spectroscopy(SIMS) depth profile of an
ultrashallow junction formed by the 0.5-1 keV boron implantation method. The
modeling of the boron profile was performed using the Monte Carlo method for
an as-implanted profile and the computationally efficient method for transient
enhanced diffusion. A junction depth of less than 300Å
can be obtained by
rapid thermal annealing at 900°C for B implantation at 0.5 keV.
In the case of annealing at 1000°C, the junction depths were
approximately 500–550Å
for both 0.5 keV and 1 keV. For the same equivalent
energy, the junction depth of BF2 is shallower than that of boron
after annealing. For an ultrashallow junction, HF dipping prior to rapid thermal
annealing causes a significant loss of dopant and high sheet resistance.
Frustrated Structure Induced on Ferroelectric Smectic Phases in Banana-Shaped Molecular System
Authors: Watanabe Junji , Niori Teruki , Sekine Tomoko , Tekezoe Hideo
Published: October 2002

We found that the frustration, i.e., unusual density modulation, is induced on ferroelectric SmAb and HexBb phases composed of achiral banana-shaped molecules. The frustration takes place along the bent direction of molecules, with four or five molecules included in each inversion unit. Such an unusual frustrated structure may be explained as a result of a two-dimensional escape from spontaneous polarization in the ferroelectric phases.
Improvement of Current-Voltage Characteristics in Organic Light Emitting Diodes by Application of Reversed-Bias Voltage
Authors: Zou Dechun , Yahiro Masayuki , Tsutsui Tetsuo
Published: October 2002

The effects of reversed-bias application on current-voltage and luminance-voltage
characteristics of standard-type double-layer organic light emitting
diodes [OLEDs], ITO/TPD(50 nm)/Alq3(50 nm)/Mg:Ag, were investigated.
Both the magnitude of reversed-bias and the duration of reversed-bias
application were systematically changed. Evident voltage shifts towards the
lower voltage side in current-voltage and luminance-voltage characteristics
were observed in the diodes which were treated under various reversed-bias
condition. The longer the duration of reversed-bias application, the larger the
voltage shift was. A maximum voltage shift of 0.7 V was observed in the diode
treated under a -10 V bias for 3 h. Little change in luminance-current density
relationships was observed for diodes which were treated under various
reversed-bias conditions. The results were interpreted in terms of the
movement of ionic impurities and orientational rearrangements of permanent
dipoles in organic layers.
Short-Time Information Entropy as a Complexity Measure
Authors: Masahiro Agu Masahiro Agu , Mitsuhiro Yamada Mitsuhiro Yamada
Published: October 2002

1/f fluctuation observed in many physical, chemical, or biological stochastic processes is expected to be the most efficient for producing “information”, or to have the best capability of “computation”. In order to measure the complexity of the information included implicitly in the fluctuation, we introduce a unit length of the time series of fluctuation based on a relaxation time of the correlation intensity and define the short-time information entropy of the unit time series. Simulation results show that the short-time information entropy of the 1/f fluctuation is the maximum among f
-ν (0<ν<2) fluctuations.
Lasing Emission from an In0.1Ga0.9N Vertical Cavity Surface Emitting Laser
Authors: Takao Someya Takao Someya , Koichi Tachibana Koichi Tachibana , Jungkeun Lee Jungkeun Lee , Takeshi Kamiya Takeshi Kamiya , Yasuhiko Arakawa Yasuhiko Arakawa
Published: October 2002

Lasing action in an In0.1Ga0.9N vertical cavity surface
emitting laser was successfully achieved, for the first time, at a wavelength of 381 nm.
The 3λ vertical cavity comprising an In0.1Ga0.9N active
region was grown on a GaN/Al0.34Ga0.66N quarter-wave reflector by
metal organic chemical vapor deposition (MOCVD), and covered with a
TiO2/SiO2 reflector by electron-beam evaporation. The laser was
operated at 77 K under optical excitation. We have observed a significant narrowing
of the emission spectrum from 2.5 nm below the threshold to 0.1 nm (resolution limit)
above the threshold, which is a clear signature of lasing action.
Difference in Low Frequency Raman Spectra between Dehydrated Egg White and the Dehydrated Heat-Treated Gel
Authors: Atsushi Nakamura Atsushi Nakamura , Kazuhiro Hara Kazuhiro Hara , Nobuyasu Hiramatsu Nobuyasu Hiramatsu
Published: October 2002

Low frequency Raman spectra of dehydrated egg white (DEW) and dehydrated heat-treated egg white gel (DHTEWG) were investigated in order to distinguish characteristics spectroscopically. A notable difference has been revealed in the low-lying band frequency; in DEW, it was approximately the same as that of the boson peak reported on many amorphous materials or glasses, on the other hand, in DHTEWG, the frequency was 2∼3 times that in the conventional ones. This feature was considered the result of the crosslink of the polymer network in DHTEWG formed before dehydration.
Improvement of Al/GaAs Schottky Junction Characteristics Using a Thin Praseodymium Interlayer
Authors: Lin Jengping , Hwu Ming-Jyh , Chang Liann Be
Published: October 2002

A thin praseodymium interlayer with a thickness of less than 3.5 nm at the Al/GaAs
Schottky junction is shown to reduce the reverse bias leakage current by more than two orders
of magnitude and enhance the Schottky barrier height by 0.12 eV. The significant reduction
of reverse bias leakage current cannot be explained by the barrier height enhancement alone.
Formation of interfacial praseodymium oxide and gettering of n-type dopant in GaAs
substrates by the praseodymium interlayer needs to be taken in to account to explain the
results. Furthermore, it was found that the cut-in voltage of forward current increases
significantly with the Pr oxidation time, which is very useful in the fabrication of
enhancement-type transistors for high-speed integrated circuits.
Laser Diode Array Pumped Q-Switched Nd:YVO4 Mini-Disc Laser with V-Folded Cavity
Authors: Zhuo Zhuang , Chong Tow C. , Kwek Chin Wee
Published: October 2002

A new simple efficient Q-switched Nd:YVO4 mini disc laser pumped with a laser diode array is presented
with a V-folded cavity. Its output properties are characterized and the thermal effect is analyzed. The
optical-optical conversion efficiencies up to 68% for free-running operation and 8.7% for Q-switching
operation are demonstrated with a nearly diffracted-limited beam.
Helicity-Modulation Technique Using Diffractive Phase Retarder for Measurements of X-ray Magnetic Circular Dichroism
Authors: Motohiro Suzuki Motohiro Suzuki , Naomi Kawamura Naomi Kawamura , Masaichiro Mizumaki Masaichiro Mizumaki , Akiri Urata Akiri Urata , Hiroshi Maruyama Hiroshi Maruyama , Shunji Goto Shunji Goto , Tetsuya Ishikawa Tetsuya Ishikawa
Published: October 2002

A diamond X-ray phase retarder has been combined with
a phase-sensitive detection method to improve the accuracy
of X-ray magnetic circular dichroism (XMCD) measurements.
Fluctuation of the absorption coefficient of a magnetized sample
was induced by photon-helicity switching at 40 Hz by flipping the
phase retarder, and directly detected through a lock-in amplifier
referring to the helicity-modulation frequency.
This new technique for XMCD measurements was applied to
the Fe K-edge in pure Fe foil.
XMCD spectra of higher signal-to-noise ratio were obtained in
shorter measuring time.
Analysis of Tunnel Current through Ultrathin Gate Oxides
Authors: Fukuda Masatoshi , Mizubayashi Wataru , Kohno Atsushi , Miyazaki Seiichi , Hirose Masataka
Published: October 2002

Tunnel current through 1.27-8.12-nm-thick gate oxides has been calculated on the basis of
multiple-scattering theory, in which the SiO2 layer is segmented into multiple rectangular
potential barriers. By using the conduction band barrier height of 3.34 eV determined for the
SiO2/Si(100) interfaces, a tunneling effective mass of 0.35m
0 is obtained so as to reproduce
the SiO2 thickness dependence on the direct tunnel current. The Fowler-Nordheim tunnel
current oscillation due to interference between the propagating electron wave at the SiO2
conduction band and the wave reflected at the SiO2/Si interface has also been explained by
employing an oxide conduction band effective mass of 0.60m
0. It is found that the oxide
thicknesses determined by ellipsometry are in good agreement with those extracted by fitting the
measured tunnel current to theoretical one.
Analysis of an Oxygen Dissolution Process Concerning Czochralski (CZ) Si Crystal Growth using the Sessile Drop Method
Authors: Huang Xinming , Saitou Keijirou , Sakai Susumu , Terashima Kazutaka , Hoshikawa Keigo
Published: October 2002

A new sessile drop method has been developed for measuring the oxygen dissolution rate from silica glass to silicon melt. Compared to the oxygen dissolution rate obtained using a conventional measurement method, a much larger value has been obtained with the sessile drop method. The experimental accuracy of the sessile drop method was analyzed, and it was found that the main error resulted from the weight change of a blank silica plate following heat treatment. A rectification method was suggested.
Textured ZnO Thin Films for Solar Cells Grown by a Two-step Process with the Atomic Layer Deposition Technique
Authors: Sang Baosheng , Yamada Akira , Konagai Makoto
Published: October 2002

B-doped ZnO films are prepared on Corning 7059 glass by atomic layer deposition (ALD) using diethylzinc (DEZn), H2O as reactant gases, and diborane (B2H6) as a dopant gas. A two-step deposition process is introduced to grow textured and low-resistivity ZnO films by combining the ALD and conventional photo-induced metalorgainc chemical vapor deposition (photo-MOCVD) techniques. The electrical and optical properties of ZnO films are effectively improved by depositing lower-resistivity ALD-ZnO films on the textured photo-MOCVD-ZnO films while the textured surface morphologies are well maintained. Furthermore, the resistivity of the ALD-ZnO film was further improved by the two-step process and a low resistivity of 2.0×10-4 Ω·cm was achieved for the film which was only about 400 nm thick.
Observation of CuPt-Type Ordered Structure in CdZnTe during Organometallic Vapor Phase Epitaxial Growth
Authors: Kwon Myoung Seok , Lee Jeong Yong , Suh Sang Hee
Published: October 2002

A CuPt-type ordered structure in CdZnTe has been observed in HgCdTe/Cd
x
Zn1-x
Te/GaAs grown by interdiffused multilayer processing. Selected area electron diffraction and cross-sectional, high-resolution transmission electron microscopy have been employed to identify the ordered structure in CdZnTe. Selected area electron diffraction patterns showed two sets of {1/2 1/2 1/2} extra spots with symmetrical intensity through [110] projection, but no extra spots through [110] projection. In the [110] projection, high-resolution images of ordered CdZnTe showed the doubling periodicity along [111] or [111] through [110] projection. It was determined that the two variants of CuPt-type ordered CdZnTe were formed on (111) or (111) through [110] projection. The two variants were observed with almost equal probability and had similar domain structures.
Hole-Injection-Induced Structural Transformation of Oxygen Vacancy in α-Quartz
Authors: Atsushi Oshiyama Atsushi Oshiyama
Published: October 2002

Charge-state-dependent structural stability of oxygen vacancy in α-quartz is determined by using first-principles total-energy calculations. It is found that neutral and positively charged oxygen vacancies show bistability, and that a spontaneous structural transformation occurs for doubly positively and doubly negatively charged states. The structural transformation induces a new electron trap, possibly causing the degradation of SiO2 thin films.
Formation of Submicron Copper Sulfide Particles Using Spray Pyrolysis Method
Authors: Lenggoro I. Wuled , Kang Yun Chan , Komiya Takafumi , Okuyama Kikuo , Tohge Noboru
Published: October 2002

The morphology and crystalline phase of submicron copper sulfide particles prepared by spray pyrolysis method have been studied. In a nitrogen gas atmosphere, the covellite phase (CuS) spherical particles could be prepared using the solution with molar ratio of copper nitrate to thiourea and furnace temperatures of 1:2 at 200–300°C, as well as of 1:5 at 200–600°C. The crystalline phase of particles was highly depended on the composition of the precursors and the pyrolysis temperature. The sphericity of particles could be enhanced by increasing the temperature and prolonging the residence time of the droplets or particles in the furnace.
Conditions for the Formation of Ring-Like Distributed Stacking Faults in CZ-Si Wafers
Authors: Kissinger Gudrun , Vanhellemont Jan , Lambert Ulrich , Gräf Dieter , Grabolla Thomas , Richter Hans
Published: October 2002

The influence of ramp rate and starting temperature of the ramp on the generation of ring-like distributed stacking faults during wet oxidation of CZ-Si wafers was investigated. These parameters determine the average emission rate of interstitials required to maintain strain-free growth of oxide precipitates. This emission rate correlates well with the density of oxidation induced stacking faults. It indicates that the higher the required emission rate, the more strain is built into the growing oxide precipitates because of insufficient interstitial generation. This results in an increased nucleation of stacking faults.
Arsenic Precipitate Accumulation in Alternately Si/Be Delta-Doped GaAs Grown by Low-Temperature Molecular Beam Epitaxy
Authors: Hsieh Li Zen , Huang Jin Hua , Su Zi Ang , Wu Meng Chyi
Published: October 2002

The precipitation of arsenic in alternately [Si]=1.0×1013 cm-2 and [Be]=1.0×1014 cm-2 delta-doped GaAs grown at low temperature by molecular beam epitaxy has been studied using transmission electron microscopy. Following annealing at 600, 700 and 800°C, As precipitates were found to form preferentially not only on planes of Si but also on planes of Be. The as-grown and annealed samples were also characterized using secondary ion mass spectroscopy, and the results revealed that the interdiffusion of Si and Be dopants due to annealing was discernible. This is the first observation of As precipitate accumulation on Be delta-doped planes in low-temperature-grown GaAs.
Effects of Light on a P-Channel InGaP/GaAs/InGaAs Double Heterojunction Pseudomorphic Modulation-Doped Field Effect Transistor
Authors: Kim Hwe-Jong , Kim Dong-Myong , Kim Sun-Ho , Lee Jung-Il , Kang Kwang-Nham , Cho Kyuman
Published: October 2002

We report on the effects of light on a p-channel In0.49Ga0.51P/GaAs/In0.13 Ga0.87As pseudomorphic modulation-doped field effect transistor (MODFET) with a 1 µm gate length. The threshold voltage (V

t
h
), obtained in the saturation region, shows nonlinear behavior with an increase in the incident optical power (P
opt). We obtained threshold voltages ranging from V
tho=1.35 V at P
opt=0 mW to V
th=1.55 V at P
opt=2.15 mW. The photocurrent was -0.37 mA at V
gs=0 V and V
ds=-3.5 V with incident optical power of 2.15 mW. The photocurrent is defined as the difference between the drain current with optical illumination and that without optical input. The absolute value of the photocurrent increases nonlinearly with optical power. We observed that the saturated drain currents had a critical point at the gate-source voltage of 1.4 V. This property is expected to be related to nonlinearly increased channel opening under optical illumination, particularly at high gate-source voltages. The current gain cut-off frequency and the maximum frequency of oscillation were also observed to be improved under optical illumination.
Pantomime Effect in the Perception of Volumetrical Transparent Illusory Object with Binocular Viewing
Authors: Qi Zhang Qi Zhang , Masanori Idesawa Masanori Idesawa , Yutaka Sakaguchi Yutaka Sakaguchi
Published: October 2002

Transparency and volume perception are important issues in 3-D object perception. We report here a new visual effect in 3-D illusory object perception with binocular viewing, named `pantomime effect', and introduce a new framework of the effect based on three types of `sustaining cues'. We also compare sustaining cues with occlusion cues. In addition, the perception of transparent and volumetrical objects was verified by the experiments using another illusory probe stimulus. It was also found that side sustaining cues played an essential role in volume perception, and the transparency in pantomime effect was different from that in multilayer transparent planes depicted by a random dot stereogram.
Magnetotransport Properties of a Single-Crystalline β-FeSi 2 Layer Grown on Si(001) Substrate by Reactive Deposition Epitaxy
Authors: Takashi Suemasu Takashi Suemasu , Ken'ichiro Takakura Ken'ichiro Takakura , Masaya Tanaka Masaya Tanaka , Tetsuo Fujii Tetsuo Fujii , Fumio Hasegawa Fumio Hasegawa
Published: October 2002

We report on the magnetotransport properties of a single-crystalline semiconducting β-FeSi2 layer for the first time. A single-crystalline 5000-Å-thick β-FeSi2 layer was prepared on Si(001) by a two-step reactive deposition epitaxy (RDE). Magnetotransport measurements showed the occurrence of anomalous Hall effect and negative magnetoresistance in the β-FeSi2 layer below 77 K. The Arrott plot indicated the possibility that the single-crystalline β-FeSi2 exhibits ferromagnetic behavior below 15 K.
The Effect of Biaxial Stress on the Solid Phase Epitaxial Crystallization of GexSi(1-x) Films
Authors: Corni Federico , Frabboni Stefano , Tonini Rita , Leone Daniela , de Boer Wiebe , Gasparotto Andrea
Published: October 2002

Two fully-strained, Si rich, Ge
x
Si(1-x) alloys deposited on (100) Si by CVD were amorphized including part of the substrate and recrystallized at different temperatures in the range 500–620°C. The amorphous-crystal interfaces remain flat during crystallization, and the films grow coherently with the substrate producing crystalline, defect-free, strained heteroepitaxial layers. The kinetics of the process, compared with literature data of the corresponding relaxed alloys, are affected by the presence of the in-plane stress at the interface, resulting in a decrease of the velocity, in quantitative agreement with the predictions of the activation strain model in the case of biaxial stress.
Self Assembly of Organic Microcrystals 1: Electrostatic Attachment of Polydiacetylene Microcrystals on a Polyelectrolyte Surface
Authors: Tripathy Sukant K. , Katagi Hideyuki , Kasai Hitoshi , Balasubramanian Srinivasan , Oshikiri Hiroyuki , Kumar Jayant , Oikawa Hidetoshi , Okada Shuji , Nakanishi Hachiro
Published: October 2002

A new approach to processing organic microcrystals through electrostatic self assembly is presented. Organic microcrystals produced by a recently reported method in an aqueous medium are charge stabilized and electrostatically adsorbed on oppositely charged polyelectrolyte coated substrates. Dense “microcrystal-monolayer” coverage can be achieved by producing a coherent film of the thickness defined by the microcrystal dimension. Layer-by-layer deposition for thick film growth and adsorption on patterned substrates will be the approaches for further processing of the microcrystal systems.
Application of Chemical Imaging Sensor to Electro Generated pH Distribution
Authors: Yoshinobu Tatsuo , Iwasaki Hiroshi , Nakao Motoi , Nomura Satoshi , Nakanishi Tsuyoshi , Takamatsu Shuji , Tomita Katsuhiko
Published: October 2002

The scanning-laser-beam chemical imaging sensor was applied for the observation of electrogenerated pH distribution on a mesoscopic scale. Electrolysis was carried out in potassium chloride solution and the resulting pH distribution was imaged with a 0.2 mm spatial resolution. As a result, the generation of the pH distribution and its expansion to the bulk region were clearly imaged. By examining the pH image, it was also possible to obtain the pH values in the pH-distributed regions separately from those in the bulk region.
Growth of a NdBaCuO Superconducting Thin Film on a MgO Substrate by Mist Microwave-Plasma Chemical Vapor Deposition Using a CeO2 Buffer Layer
Authors: Takahashi Naoyuki , Takeda Naoyuki , Koukitu Akinori , Seki Hisashi
Published: October 2002

A NdBaCuO superconducting thin film was grown by mist microwave-plasma chemical vapor deposition (MPCVD) using a CeO2 buffer layer on a MgO(001) substrate. After the CeO2 buffer layer was deposited on the MgO(001) substrate at 1173 K by MPCVD, a NdBaCuO film was grown at 1223 K. The T
c-zero (zero resistance) value of the NdBaCuO film with the CeO2 buffer layer was 90.1 K, and it was about 10 K higher than that without the CeO2 buffer layer. The surface roughness of the NdBaCuO film was less than 5 nm.
Possibility of Reduction in Hysteresis Loss Due to Reversible Fluxoid Motion in a Superconducting Bi-2223 Multifilamentary Wire
Authors: Otabe Edmund Soji , Matsuoka Hiroshi , Matsushita Teruo , Fujikami Jun , Ohmatsu Kazuya
Published: October 2002

The energy loss density was measured and the AC penetration depth, λ0', was estimated from the slope of a minor magnetization curve for a superconducting Bi-2223 multifilamentary tape at various temperatures under the application of a parallel AC magnetic field to the tape. It was found that at high temperatures λ0' was comparable to the filament thickness and the energy loss density was lower than that predicted using a modified Kim's model taking into account the effect of the diamagnetism. This reduction is ascribed to the reversible fluxoid motion inside pinning potential wells. The reduction of the filament thickness to less than 2 µm is recommended for the achievement of the low energy loss density at 77 K.
Antiferroelectric Smectic Liquid Crystal Formed by Achiral Twin Dimer with Two Mesogenic Groups Linked by Alkylene Spacer
Authors: Watanabe Junji , Niori Teruki , Choi Suk-Won , Takanishi Yoichi , Takezoe Hideo
Published: October 2002

We have studied antiferroelectricity in twin dimers, in which two mesogens with alkyl tails are linked by an alkylene spacer. Since the conformation of dimers is confined by the spacer, the use of the spacer with an odd carbon number forces the dimer to assume a bent conformation. If a segregation between the spacer and tail takes place in such odd-numbered dimers, the smectic structure formed is biaxial with bent molecules packed into a layer with the same bent directionality. Due to this characteristic packing, the spontaneous polarization appears parallel to the layer even in an achiral system. According to this understanding, we have obtained the antiferroelectric smectic liquid crystal which shows the distinct tristable switching phenomenon with the application of a triangular voltage wave.
New Computed Tomography Algorithm of Electrostatic Force Microscopy Based on the Singular Value Decomposition Combined with the Discrete Fourier Transform
Authors: Ryuji Nishi Ryuji Nishi , Yoshizumi Nakao Yoshizumi Nakao , Takayuki Ohta Takayuki Ohta , Yasuhiro Sugawara Yasuhiro Sugawara , Seizo Morita Seizo Morita , Takao Okada Takao Okada
Published: October 2002

A new algorithm for three dimensional electrostatic force microscopy, which deduces the charge distribution in a sample from a horizontal distribution of a gradient of electrostatic force measured above the sample surface, was proposed. One dimensional horizontal distribution of the electrostatic force gradient was transformed into frequency space and the singular value decomposition was performed. Very small singular values were removed and then the inverse matrix was calculated. This method was more tolerant of noise than the conjugate gradient method. Even with 0.1% noise in the distribution of force gradient, the charge even in the fourth layer can be reconstructed.
Preparation of Organic Silica Films with Low Dielectric Constant from the Liquid Phase
Authors: Koh-ichi Usami Koh-ichi Usami , Kazuhito Sumimura Kazuhito Sumimura , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Silica films with dense methyl-groups were grown from the liquid phase using methyl-triethoxy-silane, aiming at inter-metal-dielectrics applications. The film showed insulating characteristics even under as-deposited conditions. The dielectric constant, low-field resistivity and breakdown field-strength were 4.5, 3×1013 Ω cm and 1 MV/cm, respectively. They were improved to 2.9, more than 5×1014 Ω cm and more than 2 MV/cm, respectively, after 400°C vacuum annealing.
Room Temperature Operation of Amorphous Carbon-Based Single-Electron Transistors Fabricated by Beam-Induced Deposition Techniques
Authors: Miura Naruhisa , Numaguchi Tetsuyuki , Yamada Akira , Konagai Makoto , Shirakashi Jun-ichi
Published: October 2002

Single-electron transistors (SETs) were directly fabricated using scanning electron microscopy (SEM) and a focused ion beam (FIB) system. Amorphous carbon microstructures were modified to the source, drain electrodes and the capacitive island using SEM. The gate electrode consisting of tungsten carbide deposited by FIB was also supplemented. Namely, microscopic tunnel junctions were prepared by beam-induced reaction processes, which are simple and unique techniques for microfabrication. At room temperature, a Coulomb staircase and Coulomb blockade oscillation were successfully recorded, and this beam-induced method was confirmed to be one of the practical processes for realizing SETs.
Oxidation of GaAs Using Helicon-Wave Excited Nitrogen-Oxygen-Argon Plasma
Authors: Satoshi Wada Satoshi Wada , Fumio Kasahara Fumio Kasahara , Akio Hara Akio Hara , Hideaki Ikoma Hideaki Ikoma
Published: October 2002

GaAs (100) substrates were exposed to the helicon-wave excited N2–O2–Ar plasma without and with substrate heating at 200°C. The oxide dominantly composed of Ga2O3 and As2O3, was grown on the GaAs substrate using this technique. The chemical composition of this oxide was highly uniform along the thickness of the oxide film. Relatively good capacitance-voltage (C–V) characteristics were obtained. X-ray photoelectron spectroscopic data indicated that gallium nitride (GaN) bonds were formed at the oxide/GaAs interface only with both substrate heating and post-thermal annealing at 200°C for 30 min in a nitrogen ambient. The formation of the GaN/GaAs interface improved the C–V characteristics to some extent.
Enhancement of Second-Harmonic Power Due to Self-Construction of an Anti-Guide Structure in a Thin-Film Waveguide of a Nonlinear-Optical Photoconducting Polymer
Authors: Sassa Takafumi , Umegaki Shinsuke
Published: October 2002

A theoretical analysis, to explain the increase of the Cerenkov-radiation-type second-harmonic power with time in a thin-film waveguide of a nonlinear-optical photoconducting polymer, is given. An anti-guide structure, which confines both a fundamental wave and its second-harmonic wave, is gradually constructed by reorientation of the nonlinear-optical chromophores within the fundamental beam width in the thin-film polymer. The space-charge field formed by the initially weak second-harmonic wave itself causes the reorientation.
Similarities in Spatial Distributions of Absolute GeH2 Density, Radical Production Rate and Particle Amount in GeH4 RF Discharges
Authors: Kawasaki Hiroharu , Kida Junichirou , Sakamoto Kazutaka , Fukuzawa Tsuyoshi , Shiratani Masaharu , Watanabe Yukio
Published: October 2002

In order to study the particle growth processes in GeH4 RF discharges, the spatial distribution of the absolute GeH2 density is measured for the first time together with those of particle amount and radical production rate (Ge emission intensity) in a moderately high power range of 0.5–1.0 W/cm2. The particles are generated and grow around the plasma/sheath boundary near the powered electrode, and the spatial distribution of their amount is similar to those of radical production rate and GeH2 density. Furthermore, GeH2 density is about 1010 cm-3, being close to SiH2 density in SiH4 discharges for the similar conditions of RF power and pressure. These results indicate that GeH2 is a highly reactive radical having a high production rate and hence is a candidate for the main contributor to the particle growth.
Characterization of Switching Properties of Lead-Zirconate-Titanate Thin Films in Ti-Rich Phase
Authors: Aoki Katsuhiro , Sakoda Tomoyuki , Fukuda Yukio
Published: October 2002

Switching behaviors of lead-zirconate-titanate thin-film capacitors with Ti/Zr ratios of
60/40 and 75/25 were successfully characterized by observing their switching transient currents.
The capacitor with 60/40 showed the remanent polarization density of 24.0 µ/cm2 independent
of the frequency of the external switching biases. On the other hand, the remanent polarization
density of the capacitor with 75/25 was reduced markedly with increasing the frequency. The
remanent polarization density was lowered from 23.6 µC/cm2 at
100 Hz to 13.0 µC/cm2 at 12.5 kHz. While the switching transient currents were observed as a
function of time, the lead-zirconate-titanate thin-film capacitor with 60/40 showed the typical
sharp switching transient current. In sharp contrast, the capacitor with 75/25 ratio showed a
monotonous transient current which suggests the presence of ferroelectric domains having
long time constants. Consequently, the lead-zirconate-titanate thin film with the Ti/Zr ratio of
60/40 showed better switching behavior as compared to that with the Ti/Zr ratio of 75/25.
Improvement of Effective Charges in Oxynitride Prepared by Liquid Phase Deposition on Silicon
Authors: Lee Ming-Kwei , Lin Chung-Hsing , Lei Bo-Hsiung , Yang Chi-Da
Published: October 2002

Using an aqueous solution of ammonia hydroxide aqua, hydrosilicofluoric acid and boric acid, an oxynitride film can be grown. Nitrogen atoms are accumulated at the interface of the oxynitride film and silicon substrate. With subsequent thermal annealing in nitrogen, the effective oxide charges of the oxynitride can be improved.
Enhancement of Optical Gain in Two-Dimensional Photonic Crystals with Active Lattice Points
Authors: Nojima Shunji
Published: October 2002

Photonic crystals with active lattice points (two-dimensional gain
photonic crystals) are proposed, in which all lattice points are made of the
same gain material embedded in other dissipative medium. The optical
gain spectrum is found to exhibit a pronounced gain enhancement in the
vicinity of the band edge of the photonic band. This gain value also shows
a spatial anisotropy reflecting the symmetry of the photonic band. These
gain values have a strong correlation with the variation of the group
velocity of light, indicating that the marked reduction in the group
velocity near the photonic band edge causes the optical gain enhancement.
Ion Energy Effects on Surface Chemistry and Damage in a High Density Plasma Etch Process for Gallium Arsenide
Authors: Leonhardt Darrin , Eddy Charles R. , Shamamian Jr. , Holm Ronald T. , Glembocki Orest J. , Thoms Brian D. , Katzer Daniel S. , Butler James E.
Published: October 2002

Etch product chlorides from a gallium arsenide substrate subjected to a
high density Cl2/Ar plasma etching process have been sampled in situ to
determine regions of process space commensurate with ion-driven surface
chemistry. Experimental results show three distinct surface chemistry
regimes as the ion energy is increased: thermal chemistry for energies
<50 eV, ion-assisted chemistry for energies of 50–200 eV, and
sputtering for energies above 200 eV. Further, ion energies above 200 eV
result in unrecoverable pinning of the surface Fermi level whereas at
lower ion energies the surface Fermi level returns to the pre-etch
condition with in situ Cl2/Ar plasma passivations.
Analysis of Liquid Crystal Orientation at Interface between Liquid Crystal and Alignment Film by Total Reflection Ellipsometry
Authors: Satoshi Okutani Satoshi Okutani , Munehiro Kimura Munehiro Kimura , Tadashi Akahane Tadashi Akahane
Published: October 2002

The total reflection ellipsometry (TRE) method is proposed to investigate the behavior of the liquid crystal (LC) molecules at the interface between LC and an alignment film.
Theoretical analysis indicated that the TRE method is useful for studying the behavior of interfacial LC molecules.
From the numerical results of the TRE method, it was found that the phase difference versus applied voltage depends on the polar anchoring strength.
The TRE method is sensitive enough to estimate the polar anchoring strength of LC cells.
The Strain in an Elastic Plate
Authors: Bottomley David J.
Published: October 2002

The strain distribution in an elastic plate bent in one dimension, originally
proposed by Euler and Bernoulli in 1744, is examined. On the basis of
fundamental considerations in thermodynamics, it is shown that the plane of
zero strain is shifted slightly from the central plane. This appears to invalidate
the currently-accepted interpretation of experimental data on heteroepitaxial
stress measured using the cantilever bending method. From comparison with
experimental data, doubt is cast on the strain distribution of Euler and
Bernoulli in its application to the cantilever bending method.
Aligned Carbon Nanotube Film Self-Organized on a SiC Wafer
Authors: Kusunoki Michiko , Shibata Junko , Rokkaku Masumi , Hirayama Tsukasa
Published: October 2002

An aligned carbon nanotube film was fabricated on the surface of an α-SiC
wafer by heating at 1700°C for 30 min. in a vacuum electric furnace
due to the decomposition of SiC by selected desorption. It was found to be
easy to produce a large-area carbon nanotube film on the SiC substrate.
The (0002) lattice distance of graphite constructing the CNTs was
obtained to be 0.344 nm from the electron diffraction pattern.
Formation of Thin Single-Wall Carbon Nanotubes by Laser Vaporization of Rh/Pd-Graphite Composite Rod
Authors: Maniwa Hiromichi Kataura , Hanyu Takaaki , Achiba Yohji
Published: October 2002

Single-wall carbon nanotubes (SWNTs) were synthesized in high yield by laser vaporization of a Rh/Pd-graphite composite rod at 1200 °C. Lattice constants of the bundle were estimated from transmission-electron-microscope images and were found to be distributed between 1.0 and 1.5 nm. Nine Raman peaks originating from the breathing modes were observed at 204, 215, 229, 247, 262, 272, 287, 303 and 328 cm-1. These frequencies and lattice constants sharply indicate the presence of the SWNTs indexed from (5,5) to (8,8) which are thinner than the SWNTs obtained using Ni/Co catalyst.
Toward New Cylindrical Electrostatic Micromotors Using Tubular Combination of Arrayed Direct-Drive Actuators
Authors: Minotti Patrice , Bourbon Gilles , Langlet Philippe , Masuzawa Takahisa
Published: October 2002

A new generation of electrostatic micromotors is investigated using cooperation of arrayed
direct-drive actuators. Electrostatic scratch-drive actuators (SDAs), which combine active
frictional contact mechanisms with electrostatic actuation are particularly analyzed. A
prototype of a cylindrical micromotor, whose external diameter and length are, respectively,
1 mm and 2 mm, has been realized through the insertion of a flexible active polysilicon sheet at
the rotor/motor-frame interface. The sheet, which acts as a stator, is fabricated by the surface
micromachining process and then released automatically from the silicon wafer. One thousand
four hundred thirty actuators are integrated on a 6 mm2 polysilicon sheet surface, leading to
high-driving-torque characteristics.
Influencs of Surface V/III Ratio on the Film Quality during the GaN Growth in Gas-Source Molecular Beam Epitaxy
Authors: Shen Xu-Qiang , Tanaka Satoru , Iwai Sohachi , Aoyagi Yoshinobu
Published: October 2002

GaN growth was performed on 6H–SiC (0001) substrates by gas-source molecular beam epitaxy (GSMBE), using ammonia (NH3) and solid Ga as V and III sources. Two kinds of reflection high-energy electron diffraction (RHEED) patterns, namely
(1×1) and (2×2), were observed during the GaN growth depending on the growth conditions, which correspond to nitrogen-rich and Ga-rich surfaces, respectively.
Phase diagram of the two surface states via growth conditions was also obtained, indicating the surface V/III ratio change during the growth. It was found that the GaN film quality was greatly improved under nitrogen-rich growth conditions by
X-ray diffraction (XRD) and photoluminescence (PL) characterizations.
Changes in Stress Relaxation due to Yielding in Zr 65Al 10Ni 10Cu 15 Metallic Glass
Authors: Kawamura Yoshihito , Shibata Tsutomu , Inoue Akihisa
Published: October 2002

We investigated the stress relaxation behavior of Zr65Al10Ni10Cu15 (at%)
metallic glass having a wide supercooled liquid region. The stress relaxation
was more pronounced after yielding and its relaxation rate increased with
temperature. The activation energy of the stress relaxation decreased from
165±10 kJ/mol to 108±8 kJ/mol due to the yielding. The glassy structure
appears to change into a state with higher atomic mobility due to the
yielding.
Crystallization of Nanometer–Sized Amorphous Sb Particles Formed by Flowing Gas Evaporation Technique
Authors: Tanaka Kei , Saburo Iwama Saburo Iwama , Kazuhiro Mihama Kazuhiro Mihama
Published: October 2002

Isolated amorphous Sb particles are used to obtain information on the crystallization of nanometer-sized particles. The postannealing was carried out between
110 and 150°C for 10 to 90 min and the crystallization ratio was measured by the dark field electron microscopic observation. The activation energy for crystallization
shows a particle-size dependence, that is, it increases from 1.85 to 2.01 eV with the decrease in diameter from 30 to 10 nm. The size dependence is discussed in relation
to the hydrostatic pressure effect induced by the small surface curvature of the particles.
Influence of Modulation Wavelength on the Structure of TiC/W Multilayers
Authors: He Jian-Li , Li Wen-Zhi , Li Heng-De
Published: October 2002

TiC/W multilayers with modulation wavelength ranging from 9 nm to 45 nm were
prepared by ion beam sputtering deposition at nearly ambient temperature. It was found that
epitaxial growth can be obtained. The orientation relationship was always (100)W//(100)TiC
and [011]W//[001]TiC. Modulation wavelength was found to have a determinant influence on
whether epitaxial superlattices would be produced or randomly-orientated polycrystalline
multilayers would be produced. With decreasing modulation wavelength, TiC/W multilayers
experienced a transition from typical polycrystalline multilayers to highly-orientated epitaxial
superlattices. The possible explanation is discussed.
Pico-Newton Friction Force Measurements Using a Laser-trapped Microsphere
Authors: Inouye Yasushi , Shoji Satoru , Furukawa Hiromitsu , Nakamura Osamu , Kawata Satoshi
Published: October 2002

We have developed a system for measuring the force of friction by using
the technique of laser-trapping. A polystyrene microsphere of a 3 µm
diameter is trapped in a water layer using a focused near infrared
laser. While the sample is scanned, all of the viscous, friction, and
radiation forces are induced in the microsphere. The friction force
acting on the microsphere is estimated by the viscous force obtained
from the scanning speed of the stage using Stokes law, and
the radiation force is obtained by the displacement of the microsphere.
We demonstrate experimentally the existence of a linear relationship
between the force of radiation and the displacement. We found that the
value of the spring constant of the radiation force is 7.2 µN/m.
Furthermore, we measured both the friction force acting on the probe on
a flat quartz substrate surface and that at the edge of small steps.
The magnitude of these forces are 0.88 pN and 1.23 pN, respectively.