bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser-Induced Removal of Fingerprints from Glass and Quartz Surfaces
Authors: Yong-Feng Lu Yong-Feng Lu , Shuji Komuro Shuji Komuro , Yoshinobu Aoyagi Yoshinobu Aoyagi
Published: October 2002

Laser removal of fingerprints from glass and quartz surfaces was studied using laser irradiation in air. The KrF excimer laser, continuous wave (CW) CO2 laser and pulsed CO2 laser were used in the investigation. Electron probe microanalysis (EPMA) was performed to characterize the substrate surfaces before and after laser cleaning. It is found that short wavelength and pulse width are necessary for fingerprint removal. EPMA measurements show that KrF excimer laser irradiation can effectively remove fingerprints from glass and quartz surfaces with a few pulses if the pulse energy density is sufficiently high. In the laser removal of fingerprints from quartz surfaces, it is found that the irradiation direction of the incident laser pulse can cause significant differences in the cleaning effect for laser irradiations from the front or back. CO2 laser irradiation, either in CW or pulse form, cannot effectively remove fingerprints.
Intensity Variation of Transition Radiation Induced by Adsorption of Nitrogen on W(100) Surface
Authors: Tanaka Masatoshi , Ota Koyu , Hirokatsu Miyatake Hirokatsu Miyatake , Seiji Usami Seiji Usami
Published: October 2002

The intensity of p-polarized ultraviolet radiation emitted from a nitrogen-covered W(100) surface irradiated with 1.5 keV of electrons has been measured at high observation angles, where the observed radiation is dominated by transition radiation. The intensity varies about 1% upon nitrogen adsorption. Its dependence on exposure agrees with the well-established fact that there are two kinds of adsorption sites. The variation of the complex dielectric function (Δε) is then obtained from the intensity variations at two observation angles. Difference in Δε between λ=300 nm and 380 nm is briefly discussed concerning surface electronic states.
Influence of Surface Roughness on Secondary Electron Emission and Electron Backscattering from Metal Surface
Authors: Nishimura Kenji , Itotani Takayuki , Ohya Kaoru
Published: October 2002

Because of its acute importance in the understanding of low-energy ( ≤1 keV) electron-material interactions in thermonuclear fusion devices, the effect of surface roughness on the secondary electron yield and backscattering coefficient, as well as on the energy and angular distributions of emitted electrons, is investigated using a Monte Carlo simulation combined with a model of ripple structure for the roughness. Two different effects of surface roughness are demonstrated. One is that low-energy and obliquely oriented electrons, which cannot escape from a flat surface, can escape from an inclined plane of the rough surface. The other is that electrons emitted near the bottom of the rough area re-enter into the surface. The former effect, which is dominant for small roughness, causes an increase in the secondary electron yield and an increase of the low-energy component in the energy distribution. The latter effect, which is dominant for large roughness, causes a decrease in the secondary electron yield and backscattering coefficient, as well as angular distributions of the over-cosine type.
Simple Method to Determine Collisional Event in Monte Carlo Simulation of Electron-Molecule Collision
Authors: Kenichi Nanbu Kenichi Nanbu
Published: October 2002

A simple method to determine collisional event is proposed for the use in the Monte Carlo simulation of electron-molecule collision.
Phase-Shifting Ellipsometer
Authors: Chu Cheng-Wei , Lee Cheng-Chung , Fu I-Yung , Jin-Cherng Hsu Jin-Cherng Hsu , Yeuh-Yeong Liou Yeuh-Yeong Liou
Published: October 2002

A new type of automatic ellipsometer based on a phase-shifting technique is described, where an electrooptic modulator made of ADP (ammonium dihydrogen phosphate) crystals is used for phase shifting; thus we call it the phase-shifting ellipsometer. The light source is a 5 mW He-Ne laser. The intensities changed as the phase retardation Γ was shifted by 0, π/2 and π. The design, alignment, and calibration of the system are discussed in detail. Once the optical system is aligned, all components are free from mechanical movement, hence the precision is high. The accuracy of the results has been evaluated, and the errors introduced on Ψ and Δ are <0.032° and 0.19°, respectively. The inaccuracy of the phase shift can only introduce an error on Δ, and the degree of error on Δ is the same as that on Γ, so it is very easily to modify.
Band Offset Transitivity in the AlGaAs/GaP/InP System
Authors: Meléndez Juan , Armelles Gaspar , Mazuelas Angel , Ruiz Ana , Bacquet Gerard , Hassen Fredg
Published: October 2002

Two samples consisting of five periods of a GaP/InP short-period superlattice clad by AlGaAs layers have been grown by atomic layer molecular beam epitaxy, and have been structurally characterized by X-ray diffraction. Low-temperature photoluminescence and excitation photoluminescence measurements using circular polarization excitation and detection techniques have been performed. Results can be explained if the offset between AlGaAs/GaP is the one governed by the transitivity rule, provided a very small segregation is assumed in the GaP/InP system.
X-Band Mixing Performance of Y1Ba2Cu3O7-x Step-Edge Junction
Authors: Yoshikawa Shuichi , Yamaguchi Keiichi , Takenaka Tsuyoshi , Fujino Shuichi , Mitsuzuka Tsutomu , Hayashi Kunihiko , Katsumi Suzuki Katsumi Suzuki , Youichi Enomoto Youichi Enomoto
Published: October 2002

The X-band mixing performance of some step-edge junctions using Y1Ba2Cu3O7-
x

films has been evaluated. The mixing conversion efficiency (η) depends predominantly on normal resistance (R
n) of a junction, which determines impedance matching for the microstrip signal line. Under constant impedance conditions obtained from temperature dependence of R
n, conversion efficiency (η) increases with increase of the I
c
R
n product. In the range of 12 GHz, however, the efficiency is saturated above the I
c
R
n product of 1 mV. This tendency agrees with our simulation based on the resistively shunted junction (RSJ) model.
Al–Pd–Re Icosahedral Quasicrystals and Their Low Electrical Conductivities
Authors: Yuko Honda Yuko Honda , Keiichi Edagawa Keiichi Edagawa , Akinori Yoshioka Akinori Yoshioka , Tatsuo Hashimoto Tatsuo Hashimoto , Shin Takeuchi Shin Takeuchi
Published: October 2002

In the Al–Pd–Re system, two kinds of icosahedral phases (I-phases) with different quasilattice constants have been found to form at 1173 K. The I-phase with larger quasilattice constant is formed in a wide composition range at 1173 K: 13–25 at.%Pd and 10–15 at.%Re. The conductivity of single-I-phase samples varies greatly with the alloy composition and also from sample to sample for the same nominal composition, and is generally quite low; in some samples of Al70Pd20Re10 it is 0.5 Ω-1cm-1 at 4.2 K, the lowest value ever reported for quasicrystals. The magnetoconductivity at helium temperatures changes systematically with the conductivity value of the sample; it is negative at low temperature with its magnitude decreasing with decreasing conductivity and becomes positive for the lowest conductivity sample. The conductivity behavior cannot be interpreted either in the framework of the weak localization or in that of conventional variable range hopping.
Anomolous Dielectric Relaxation in Nickel-Doped Barium-Strontium Titanate Ceramics
Authors: Jun'ichi Karasawa Jun'ichi Karasawa , Tatsuo Fukami Tatsuo Fukami
Published: October 2002

Dielectric properties of Ni-doped (Ba,Sr)TiO3 ceramics were investigated as a function of temperature up to 700°C. Peaks of a dielectric constant were found around 250°C depending on applied frequency. This phenomenon has been interpreted by the authors in terms of a newly proposed localized dipole model which assumes that defect dipoles are localized on each grain surface.
Further Study on Temperature, Density, and Perturber Dependences of Absorption of 3.39 µm He-Ne Laser by Methane
Authors: Takao Tsuboi Takao Tsuboi , Ping Du Ping Du , Naoko Arimitsu Naoko Arimitsu , Jean-Michael Hartmann Jean-Michael Hartmann
Published: October 2002

In order to supplement the information on the perturber dependence of absorption at 3.39 µm of the He–Ne laser by methane, the decadic molar extinction coefficients of methane diluted with helium, hydrogen and carbon dioxide have been measured. The broadening data S γ
l
( CH4–X)/ S γ
l
( CH4–Air) and β
l
( CH4–X) for He, H2 and CO2, which are available in a wide range of temperature (300–1000 K), are proposed.
Reaction Path of Internal Gettering of Iron in Semiconductor Silicon
Authors: Fabry Laszlo , Hackl Bernhard , Range Klaus-Jürgen
Published: October 2002

Iron is an effectiye minority carrier lifetime killer. Above 800° C the decomposition of thermally unstable FeSi0.7<
x
<2 species yields iron in monocrystalline silicon. The solid state reactions of migrating iron can compete with the nucleation process of interstitial oxygen. One reaction path leads to the formation thermally unstable [FeB] complex. Generally, an equilibrium manifold rules the intrinsic gettering mechanism. The rate of iron gettering is a basic function of the temperature and the number and concentration of the components involved in the equilibra. At a threshold level of about 7×1010 atoms·cm-3 iron can hinder nucleation at 780° C.
Preparation and Characterization of Sol-Gel Derived Epitaxial and Oriented Pb(Zr0.52Ti0.48)O3 Thin Films
Authors: Keiichi Nashimoto Keiichi Nashimoto , Shigetoshi Nakamura Shigetoshi Nakamura
Published: October 2002

Epitaxial and oriented Pb(Zr0.52Ti0.48)O3 (PZT) thin films were prepared from nonhydrolyzed polymeric precursors. PZT thin films with a single (001) orientation were prepared on SrTiO3 (100) and MgO (100) substrates by solid-phase epitaxial growth. Crystallization of sol-gel PZT with a (111) preferred orientation was also observed on sapphire (0001) substrates. The guided wave modes were excited by a prism coupling method for PZT thin films crystallized on MgO (100) at 700° C, and the verified refractive index was as high as 2.561. Dielectric constant and remnant polarization of epitaxial PZT thin films, crystallized on conductive Nb-SrTiO3 (100) substrates at 650° C, were 448 at 10 kHz and 15 µ C/cm2, respectively.
Formation of Metal/Ferroelectric/Insulator/Semiconductor Structure with a CeO2 Buffer Layer
Authors: Hirai Tadahiko , Teramoto Kazuhiro , Nishi Takeharu , Goto Takaaki , Tarui Yasuo
Published: October 2002

Experimental results derived from the capacitance vs voltage (C-V) characteristics of metal/ferroelectric/insulator/semiconductor (MFIS) structures are described. PbTiO3 ferroelectric films of 600 Å thickness were grown on CeO2/Si(100) substrate by digital chemical vapor deposition (digital CVD). As the buffer layer between ferroelectric and Si substrate, 150-Å-thick CeO2 intermediate epitaxial layers were grown on a (100) silicon substrate by vacuum evaporation. The density of surface states at the CeO2/Si(100) interface was estimated from the C-V characteristics of Al/ CeO2/Si(100) samples to be ∼1011/cm2 eV. Epitaxial CeO2 films on Si(100) would therefore be expected to function as the gate oxide for MFS-FET's. Furthermore, the MFIS structure has ferroelectric switching properties, as demonstrated by the roughly 1-V threshold hysleresis in C-V characteristics. This structure is thus a first step toward high-performance MFIS-FET's.
Preparation of Aluminum Nitride Epitaxial Films by Electron Cyclotron Resonance Dual-Ion-Beam Sputtering
Authors: Tanaka Naoki , Okano Hiroshi , Tatsuro Usuki Tatsuro Usuki , Kenichi Shibata Kenichi Shibata
Published: October 2002

Aluminum nitride (AlN) thin films have been deposited on (11̄·2) sapphire by an electron cyclotron resonance (ECR) dual-ion-beam sputtering method. We have thoroughly investigated the dependence of the crystallinity and surface smoothness of the AlN thin film on the assisted conditions and sputtering conditions. The AlN thin film deposited under assisted conditions with the nitrogen ion beam energy and current density of 100 eV and 0.32 mA/cm2, respectively, and sputtering conditions with the arrival aluminum flux rate to the substrate surface (Al flux rate) and argon (Ar) ion beam energy of 42 Å/min and 800 eV, respectively, is a single-crystal film with a very smooth surface. In order to prepare the epitaxial film, the Ar ion beam energy must be increased according to increases in the Al flux rate, and decreased according to decreases in the Al flux rate.
Current-Voltage Characteristics of Electron-Cyclotron-Resonance Sputter-Deposited SrTiO3 Thin Films
Authors: Fukuda Yukio , Aoki Katsuhiro , Ken Numata Ken Numata , Akitoshi Nishimura Akitoshi Nishimura
Published: October 2002

Current-voltage characteristics of SrTiO3 thin films prepared on Pt electrodes by electron-cyclotron-resonance sputtering have been studied. The leakage current characteristics of the films show an ohmiclike conduction for electric field strengths lower than about 1 MV/cm, while the leakage current for higher electric field strengths is limited by Schottky emission. These ohmiclike leakage characteristics in the low-electric-field region show strong dependences on the measurement conditions, namely, the values of voltagestep and measurement delaytime in the conventional stepwise current-voltage ramps. This result is attributed to the absorption current due to the dielectric relaxation phenomena of the SrTiO3 capacitor. The overall current-voltage characteristics can be explained by Schottky emission from the Pt electrode.
Film Thickness Dependence of Dielectric Properties of BaTiO3 Thin Films Prepared by Sol-Gel Method
Authors: Hayashi Takashi , Naoto Oji Naoto Oji , Hiroshi Maiwa Hiroshi Maiwa
Published: October 2002

Ferroelectric BaTiO3 thin films were prepared on Pt(111)/ SiO2/Si(100) substrates at 650° C by the sol-gel method. Film thickness could be varied by repeating a dip coating/heating cycle. The texture of the BaTiO3 thin films became more dense and homogeneous when the film thickness increased. The crystalline thin films showed microstructure with grains as small as 20–30 nm. The dielectric properties could be measured for films thicker than 0.25 µ m. With increasing film thickness, the dielectric constant and remanent polarization increased and the coercive field decreased. Loss tangent of the thin films was independent of the film thickness. BaTiO3 thin film with a thickness of 0.58 µ m exhibited a dielectric constant of 1000, remanent polarization of 8 µ C/cm2 and coercive field of 30 kV/cm.
Epitaxial Growth and Dielectric Properties of (Ba0.24Sr0.76)TiO3 Thin Film
Authors: Kazuhide Abe Kazuhide Abe , Shuichi Komatsu Shuichi Komatsu
Published: October 2002

A (Ba0.24Sr0.76)TiO3 thin film was epitaxially grown on a Pt/MgO(100) substrate by rf magnetron sputtering, and its dielectric properties were evaluated. The thin film had a dielectric constant of 1400 at zero bias field. A drastic decrease of dielectric constant was observed when bias field was applied. Based on the experimental results on the epitaxial film, size effects reported in the dielectric constant of (Ba

x

Sr1-
x

)TiO3 polycrystalline thin films were discussed. Both the sensitive bias field dependence of the dielectric constant and the existence of strong local fields are probably the origin of the size effects observed in (Ba

x

Sr1-
x

)TiO3 thin films.
Transient Response Characteristics of a Same-Phase Drive-Type Ultrasonic Motor
Authors: Takano Takehiro , Tomikawa Yoshiro , Aoyagi Manabu , Kusakabe Chiharu
Published: October 2002

This paper deals with a same-phase drive-type ultrasonic motor, using two degenerate bending vibration modes of a disk. Characteristics of the motor are influenced considerably by the mechanisms for supporting a stator and pressing a rotor. By investigating these points experimentally, a motor with high efficiency characteristics was realized. Moreover, the driving method for improving the transient response of the motor is described.
Stepping Drive of Self-Oscillation-Type Ultrasonic Motor
Authors: Kusakabe Chiharu , Tomikawa Yoshiro , Takano Takehiro , Aoyagi Manabu , Shoichi Inamura Shoichi Inamura
Published: October 2002

A stepping drive method that does not use an extra clock signal source for a self-oscillation-type ultrasonic motor is described. The motor used here is an in-phase drive-type ultrasonic motor using two degenerate bending vibration modes of a disk. The output electrical signals caused on a self-oscillation are used as a clock signal for the stepping drive. An angular displacement at every step is realized using an open-loop control system without a rotary encoder as an angular displacement sensor. In order to eliminate the deviation of angular displacement at every step, a multitooth rotor was used. As a result, stable stepping drive of an ultrasonic motor was realized.
Bipolar Transistor with a Buried Layer Formed by High-Energy Ion Implantation for Subhalf-Micron Bipolar-Complementary Metal Oxide Semiconductor LSIs
Authors: Kuroi Takashi , Kawasaki Youji , Ishigaki Yoshiyuki , Kinoshita Yasushi , Inuishi Masahide , Katsuhiro Tsukamoto Katsuhiro Tsukamoto , Natsuro Tsubouchi Natsuro Tsubouchi
Published: October 2002

We investigated a bipolar transistor with a buried layer formed by high-energy ion implantation without the epitaxitial silicon layer growth. We focused mainly on the reduction of junction leakage current related to implantation damages, which could be achieved by rapid thermal annealing. Consequently, the maximum current gain of 155 and the cutoff frequency of 17.3 GHz were achieved with B
V
CE0=5.0 V. Moreover, this fabrication process is applicable to the conventional complementary metal oxide semiconductor (CMOS) process with the retrograde twin wells without additional process steps. Therefore, this technique can be very promising for the fabrication of subhalf-micron BiCMOS LSIs.
Optical Switch Utilizing Total Reflection of (Pb, La)(Zr, Ti)O3 Ceramics
Authors: Toshio Utsunomiya Toshio Utsunomiya
Published: October 2002

We have previously proposed an optical deflector which consists of a (Pb, La)(Zr, Ti)O3 (PLZT) rectangular solid and triangular electrodes on its top and bottom surfaces. Applying DC voltage to both electrodes, the refractive index of the material covered by the electrodes increases and becomes different from that of the remaining part of the plate. Therefore, the part covered by the electrodes works as a prism. By increasing the applied voltage, total reflection takes place at the boundary between the part covered by electrodes and the remainder of the plate. We propose here an optical switch utilizing this total reflection, the electrodes of which are divided into three parts. By applying voltage to two of the three electrodes, the shape of the equivalent prism can be changed. Thus, the output optical beam can be deflected and switched either to the left or right. Since the beam travels straight without voltage application, it is found that this device works as a 1×3 optical switch.
Electronic Transport Properties of ZrTiO4 at High Temperature
Authors: Yamaguchi Shu , Kobayashi Kiyoshi , Iguchi Yoshiaki , Yamada Noriaki , Kato Terumasa
Published: October 2002

Electrical conductivities, using the four-probe dc method, have been measured for Zr1.012Ti0.988O4 and Zr1.009Ti0.986Y0.005O4 between 1073 and 1523 K from oxygen fugacity ( 1.013×105 Pa as a standard state) of 10-20 to 1. Thermoelectric power has also been measured for Zr1.012Ti0.988O4. Both n- and p-type conductivities are found with the dependence of -1/4 and 1/4 powers of p
O2
, respectively, and no indication of an ionic conductivity is observed. A defect model has been proposed wherein an extrinsic oxygen vacancy formation is predominant, in which the concentration of oxygen vacancy is determined by the amount of lower-valent impurities or dopants, and excellent agreement is found between experimental and calculated results. The partial conductivity of electrons showed a strong correlation with the anomalous expansion of the c-axis.
Holding Characteristic of Dark State in Antiferroelectric Liquid Crystal
Authors: Hayashi Hitoshi , Takemura Makoto , Yamada Yuichiro , Kikuchi Katsuhide , Takigawa Kenji , Inata Masashi , Hijikata Yoshimasa , Ezaka Kazuaki , Sindo Hitoshi , Orihara Hiroshi , Ishibashi Yoshihiro
Published: October 2002

The holding characteristic of the dark state of antiferroelectric liquid crystal (AFLC) displays have a crucial effect on the contrast ratio. We have studied the dependence of the transmittance in the dark state on the waveform of the applied voltage in multiplex driving for several materials. The samples used were 4-(1-methylheptyloxycarbonyl)phenyl-4′-octyloxybiphenyl-4-carboxylate (MHPOBC) and its homologues. It was found that the holding characteristics of the dark state are affected by the applied waveforms and the chemical structures such as the type of chiral radical and the length of the alkyl chain.
Pulse Response for High-Speed Nondestructive Readout in Ferroelectrics
Authors: Omura Masayoshi , Ishibashi Hiroyuki Yoshimori
Published: October 2002

Pulse responses for high-speed nondestructive readout in ferroelectrics have been studied using a ferroelectric lead zirconate titanate thin film as a memory capacitor. A critical pulse width t
*, defined as the maximum of the pulse width for which the system returns to the initial polarization state after the removal of the applied pulse field, is found to exist, suggesting the possibility of a nondestructive readout in ferroelectric memory. The observed pulse responses are compared with those of circuit simulation.
Formation Mechanism of Self-Pumped Phase-Conjugate Mirror Using a Cu-Doped (K0.5Na0.5)0.2(Sr0.61Ba0.39)0.9Nb2O6 Crystal
Authors: Gao Xin , Akira Sasaki Akira Sasaki , Yujin Zheng Yujin Zheng
Published: October 2002

In this work, we study the formation mechanism of the self-pumped phase-conjugate mirror (SPPCM) in a Cu-doped (K0.5Na0.5)0.2(Sr0.61Ba0.39)0.9Nb2O6 (KNSBN:Cu) crystal using an Ar+ laser ( λ=514 nm). The gain of self-pumped four-wave mixing is greater than that of self-generated fanning, which leads the self-formation of the SPPCM. The beam-fanning profiles vary with the laser beam incident angle. We observed that multiple fanning loops are formed and change with the change in incident angle in the SPPCM. Experimental results and discussion show that the transmission grating is responsible for the generation of the SPPCM. The phase-conjugate reflectivity increases with the increase in coupling constant.
Role of Hydrogen Plasma during Growth of Hydrogenated Microcrystalline Silicon: In Situ UV-Visible and Infrared Ellipsometry Study
Authors: Shirai Hajime , Drévillon Bernard , Isamu Shimizu Isamu Shimizu
Published: October 2002

We have applied in situ UV-visible and infrared phase-modulated ellipsometry
to investigate the role of hydrogen plasma during the growth of hydrogenated microcrystalline
silicon ( µc-Si:H) by plasma-enhanced chemical vapor deposition (PECVD).
The results of the deposition of µc-Si:H from the SiH4 highly
diluted in H2, layer-by-layer (LbL) technique and post-hydrogenation experiments
showed that the 3-dimensional cross-linking and relaxation of a Si network near the
growing surface were essential for the formation of microcrystalline silicon. The major
role of hydrogen plasma is the creation of the free volumes on the growing surface due
to the inhomogeneous etching of the Si network and the promotion of the cross-linking reactions.
Metal(CoSi2)/Insulator(CaF2) Resonant Tunneling Diode
Authors: Takashi Suemasu Takashi Suemasu , Masahiro Watanabe Masahiro Watanabe , Jun Suzuki Jun Suzuki , Yoshifumi Kohno Yoshifumi Kohno , Masahiro Asada Masahiro Asada , Nobuhiro Suzuki Nobuhiro Suzuki
Published: October 2002

Negative differential resistance (NDR) of nanometer-thick triple-barrier metal( CoSi2)/insulator( CaF2) resonant tunneling diode (RTD) and the structure dependence of its characteristics are demonstrated. The device consists of metal-insulator (M-I) heterostructures with two metallic ( CoSi2) quantum wells and three insulator ( CaF2) barriers grown on an n-Si(111) substrate. A typical peak-to-valley current ratio (P/V ratio) obtained at 77 K was 2–3 and the largest P/V ratio was 25. A P/V ratio as high as 2 was obtained at 300 K. M-I RTDs with two quantum wells of various thicknesses were fabricated in order to investigate the dependence of resonance voltage on the thickness of the two quantum wells. Reasonable agreement was obtained between theory and experiment for this dependence.
Focal Conics in Chiral Smectic C Liquid Crystals
Authors: Nobuhiko Nawa Nobuhiko Nawa
Published: October 2002

By means of a polarizing microscope, the geometrical properties of focal conics
in the chiral smectic C phase were investigated. In homogeneously aligned cells, it is
confirmed that focal conics coincide with ellipses drawn precisely by an instrument,
but small deviations are found in the eccentricity of the observed ellipses.
Extended X-Ray Absorption Fine Structure Investigations at the Silver K-Edge of Ion Exchanged Sodium Silicate Glasses
Authors: Mosel Manfred Dubiel
Published: October 2002

The present experiments were performed to study the incorporation of silver
in sodium silicate glasses by a silver-sodium ion exchange. The extended X-ray absorption
fine structure results at the silver K-edge show that the silver ions are surrounded
by oxygen in the first coordination sphere. It could be observed structural rearrangements
in dependence on both the silver-sodium exchange ratio and the thermal treatment.
Fundamental Properties and Characteristics of a Gas-Sensitive Device, Made of a Surface Acoustic Wave Device and Langmuir-Blodgett Film, Used in a Recognition System for Odoriferous Gases
Authors: Ohnishi Michihiro , Coe Ishimoto Coe Ishimoto , Masahiro Aoki Masahiro Aoki
Published: October 2002

The fundamental properties of a gas-sensitive device for the recognition of
odoriferous gases made of a surface acoustic wave (SAW) device and Langmuir-Blodgett
(LB) film were studied. An SAW device can be operated at a higher oscillation frequency
than a quartz oscillator, and an organic ultrathin film, such as the LB film, was
used as the gas-sensitive film on the SAW device. The relationship between gassensitivity
and the molecular orientation, as well as the thickness and the counterion of LB film,
was investigated. The molecular orientation and the thickness of the LB films affected
the gassensitivity. The gassensitivity of LB films incorporating counterions was
largely dependent on the electronegativity of the counterion. The characteristics
of the gas-sensitive device were elucidated and were utilized to realize the recognition system for odoriferous gases.
Mass Spectrum of Barium Oxide Vapor
Authors: Masayasu Koitabashi Masayasu Koitabashi
Published: October 2002

The evaporation products of BaO heated on a coiled platinum filament have been
studied using a quadrupole mass spectrometer while suppressing the reducing reactions
in the BaO source. The ion current ratio of Ba+ to BaO+ was 0.60±0.04,
and it was independent of the BaO source temperature. The appearance potential of BaO+
was nearly the same as the ionization energy of BaO, while the appearance potential of Ba+
was nearly equal to the sum of the ionization energy of Ba and the dissociation energy of BaO.
These observations showed that most of the observed Ba+ ions resulted from the
dissociation of BaO by electron impact in the ionization chamber of the mass spectrometer.
The proportions of Ba and BaO in the evaporation products from the actual cathodes were
estimated using the ratio 0.60, and the values obtained were reasonable.
Initial Stage of Preferential Sputtering in Cu–Pt Alloy Studied by Sputtered Neutrals Mass Spectrometry
Authors: Kunitomo Shinta , Asahata Tatsuya , Masahiko Inoue Masahiko Inoue , Ryuichi Shimizu Ryuichi Shimizu
Published: October 2002

Nonresonant multiphoton ionization sputtered neutrals mass spectrometry (NRMPI-SNMS)
was used to measure a codeposited Cu–Pt alloy film to elucidate how preferential
sputtering proceeds with ion bombardment. For this, we have newly developed a compact
coevaporator which enables preparation of Cu–Pt alloy film of homogeneous composition
from the surface to the bulk in a specimen chamber. The present study has revealed that
the ratio of sputtered Cu atoms to Pt atoms is ∼9.3 at the very initial stage of
sputtering for a Cu–Pt alloy surface of which surface composition under ion bombardment
is assessed to be Cu(88 at.%)–Pt at the topmost surface together with by the successive
atomic layers of homogeneous composition of Cu(68.2 at.%)–Pt. This result has clearly
indicated that Cu atoms are preferentially sputtered through atomic collisions caused
entirely by the kinetic process of sputtering.
Underwater Performance of Flexible Microgripper and Fine Particle Manipulation
Authors: Yoshihiko Suzuki Yoshihiko Suzuki
Published: October 2002

Underwater performance of the microfabricated flexible microgripper (FMG) using
Lorentz force actuation and electrothermal bimorph actuation is presented here. The Lorentz
force actuation was a primary factor of the actuation for the underwater operation of FMG. We
have manipulated the polystyrene fine particles successfully by using the FMG in water.
Physical Analysis for Saturation Behavior of Hot-Carrier Degradation in Lightly Doped Drain N-Channel Metal-Oxide-Semiconductor Field Effect Transistors
Authors: Goo Jung-Suk , Shin Hyungsoon , Hwang Hyunsang , Dae-Gwan Kang Dae-Gwan Kang , Dong-Hyuk Ju Dong-Hyuk Ju
Published: October 2002

This paper experimentally demonstrates that hot carrier degradation curves of lightly doped drain n-channel metal-oxide-semiconductor field effect transistors (LDDNMOSFETs) has universal behavior even if different stress conditions were applied. From this phenomena, we have proved that the Φ it/E
m, the ratio of critical barrier for interface state generation to the maximum electric field, doesn't change so that accurate lifetime prediction for drain avalanche hot carrier (DAHC) is possible using conventional log
(τI
d) vs log
(I
sub/I
d) method even if the degradation vs stress time curves show a saturation behavior. We have modeled stressed LDD as an equivalent circuit which is comprised by a surface channel MOSFET and two buried channel MOSFETs. And various circuit simulations were done by mobility change of drain side buried channel MOSFET. As a result, a modified mobility model with a lower limit parameter for mobility degradation has been developed, which successfully describes the saturation behavior of device degradation.
Density Variations in Molten Silicon Dependent on Its Thermal History
Authors: Sasaki Hitoshi , Tokizaki Eiji , Kazutaka Terashima Kazutaka Terashima , Shigeyuki Kimura Shigeyuki Kimura
Published: October 2002

Time-dependent density variations in molten silicon held at 1452° C for about 6 h depended on
the thermal process prior to holding. A slow decrease was observed after melting and heating, but a slow increase
followed cooling. Melt density reached the same stable value of 2.556 g/cm3 after both variations.
Reflecting this variation, the density of the melt measured during heating was slightly higher than that measured
during cooling. The effect of the crucible material on melt density was also studied. With an SiO2 crucible,
oxygen impurities of about 1018 atoms/cm3 were detected in the resolidified melt. The temperature
dependence of the melt density was basically the same as for a SiC-coated graphite crucible, but the anomalous
increase in melt density for temperatures near the melting point seemed to be slightly steeper.
Optical, Electrical and Structural Investigations of the Transition from Amorphous to Microcrystalline Silicon
Authors: Schoenfeld Olaf , Hempel Thomas , Zhao Xinwei , Takuo Sugano Takuo Sugano , Yoshinobu Aoyagi Yoshinobu Aoyagi
Published: October 2002

Optical and electrical properties were correlated with structural investigations during the
amorphous-to-microcrystalline phase transition of magnetron-sputtered silicon thin films. The optical characterization
was carried out using the Tauc formalism, and the electrical transport phenomena were studied by means of thermal
activated conductivity measurements. The absorption measurements show a sharp increase of the grain boundary states
corresponding to a bent Tauc plot during the crystallization. This increase of grain boundary states leads to a
drastic drop of the activation energy of the conductivity to zero. A new model of combined grain boundary states is
introduced to explain the electric and optical behavior in such new microcrystalline materials.
Preparation and Characterization of Electrodeposited CuGaxIn1-xSe2 Thin Films
Authors: Matsuoka Toshihiko , Yasushi Nagahori Yasushi Nagahori , Saburo Endo Saburo Endo
Published: October 2002

CuGa

x

In1-
x

Se2 thin films have been obtained on SnO2-coated glass by the
electrodeposition method from aqueous solution. The electrodeposition was carried out at various pH of electrolyte
and cathode potential. The compositional, structural and optical studies were carried out by a scanning electron
microscope (SEM), an energy-dispersive X-ray microanalyzer (EDX), X-ray diffractions, Raman scattering measurements
and transmissivity measurements. The X-ray diffraction study confirmed that the electrodeposited films are
single-phase solid solutions and have a chalcopyrite structure for the composition x ≤0.67.
In-Plane Aligned Y1Ba2Cu3O7-x Tapes on Metallic Substrate by Chemical Vapor Deposition Technique
Authors: Yamaguchi Taichi , Iijima Yasuhiro , Hirano Naoki , Nagaya Shigeo , Osamu Kohno Osamu Kohno
Published: October 2002

In-plane aligned Y1Ba2Cu3O7-
x

thin-film tapes have been prepared by the chemical vapor
deposition technique on a metallic substrate at 700° C. For continuous deposition on a long substrate,
tetrahydrofuran solution of Y, Ba and Cu β-diketonate chelate was slowly introduced to a vaporizer with argon
gas by a liquid flow controller. The generated gas, including source metals, was carried to a reactor with oxygen.
The orientation-controlled Y1Ba2Cu3O7-
x

thin-film tapes could be obtained by this system on
a Hastelloy C-276 substrate with an in-plane aligned yttrium-stabilized zirconia buffer layer. The critical
temperature defined by zero resistance was 88.5 K and the critical current density at 77 K in 0 T was
2.74×104 A/cm2.
Migration Path and Charge Conversion of Cations in Co-Substituted Spinel Ferrite Thin Films during Magnetic Annealing
Authors: Na Jong-Gab , Lee Taek-Dong , Park Soon-Ja
Published: October 2002

The migration path and charge conversion of cations in Co-substituted spinel ferrite thin films during magnetic
annealing are investigated. To this end, changes in the coercivity and lattice parameter were measured as a function
of magnetic annealing time. Changes in Mössbauer and X-ray photoelectron spectroscopic (XPS) spectra were also
measured. For Co-substituted ferrite thin films, peaks were observed in the plots of the coercivity and lattice
parameter vs annealing time, while those for Co-free ferrite thin films were nearly constant during magnetic
annealing. From subsequent Mössbauer and XPS experiments, it was confirmed that the peaks in the coercivity and
lattice parameter vs annealing time curves for Co-substituted ferrite thin films originate from the migration of Co
ions on octahedral sites (B sites) to tetrahedral sites (A sites) and Fe ions on the A sites to the B sites. It is
also suggested that the charge valencies of Co ions on the B sites change from +2 to +3 when they reach the A sites,
and return to +2 when they arrive at the B sites.
Correlation of Giant Magnetoresistance with Interfacial Roughness in Co/Cu Superlattices
Authors: Ueda Haruhisa , Kitakami Osamu , Shimada Yutaka , Yoshinori Goto Yoshinori Goto , Masaki Yamamoto Masaki Yamamoto
Published: October 2002

We investigate the relationship between the magnetoresistance and the interfacial roughness of Co/Cu
superlattices whose interface structures are varied by changing sputtering methods, varying sputtering gas pressure
and annealing temperatures. X-ray diffraction (XRD) experiments have revealed that the root mean square roughness
determined from low-angle XRD spectra is a good measure to evaluate the interfacial roughness which determines the
areal occupation of antiferromagnetically coupled regions and the magnetoresistance ratio.
Excess-Magnesia Effect on Pb(Mg1/2W1/2)O3–PbTiO3 Dielectrics and the Aging Phenomenon
Authors: Uchikoba Fumio , Oka Hitoshi , Tachimoto Kazushi , Takashi Ito Takashi Ito , Makoto Kobayashi Makoto Kobayashi
Published: October 2002

The effects of 0 to 10 mol% excess-MgO addition on Pb(Mg1/2W1/2)O3–PbTiO3 (PMW-PT)
solid solutions were discussed. Excess-MgO addition successively changed the ferroelectric properties of PMW-PT. The
material showed relaxor-type behavior with excess-MgO addition, whereas stoichiometric composition showed
normal-ferroelectric-like properties, and further addition of 10 mol% caused dual peaks in the temperature
dependence of the dielectric constant. These dual peaks were found to be attributed to aging phenomena. The excess
MgO improved the degree of B-site ordering and local electric field based on defects, and it was suggested that the
B-site ordering and the local field were responsible for the relaxor property and the aging effect, respectively.
Study of Layer Relaxations of Chevrons in SmC* Phase
Authors: Setsuko Mukai Setsuko Mukai , Masahiro Nakagawa Masahiro Nakagawa
Published: October 2002

In this paper, based on a continuum theory of compressible smectics, we shall analyze a layer relaxation
phenomenon between a couple of antiparallel chevrons. From the two-dimensional analyses of the layer structure and
the c-director configuration, we have found that there exist two kinds of layer relaxations depending on the
boundary conditions, i.e., dilative or compressive mode. It is found that such symmetry breaking between the
compressive geometry and the dilative one is considered to result from symmetry of the elastic free energy concerned
with layer compression. A layer undulation is found to occur in the dilative mode, but not in the compressive one.
This finding seems to correspond to the buckling instability which has been experimentally observed in the smectic
phase under layer dilation.
Direct Observation of Channel-Doping-Dependent Reverse Short Channel Effect Using Decoupled C-V Technique*
Authors: Guo Jyh-Chyurn , Hsu Charles Ching-Hsiang , Chung Steve Shao-Shiun
Published: October 2002

A non-destructive high resolution “Decoupled C-V Technique” for small geometry devices has been developed and demonstrated to successfully extract the intrinsic channel capacitance of submicron metal-oxide-semiconductor field effect transistors (MOSFET's). The effective channel doping concentration calculated from the extracted intrinsic gate capacitance presents an obvious dopant concentration enhancement in the intrinsic channel region of submicron devices compared to that of long channel devices, as the channel implant dose increases beyond a critical value. The anomalous reverse short channel effect i.e. threshold voltage increases with channel length scaled down, is simultaneously observed on the heavily doped short channel devices. The self-consistency between the C-V and I-V measurement supports that the reverse short channel effect apparent in the submicron CMOS technology is due to the channel dopant enhancement induced by high dose channel implants for both N-channel and P-channel devices.
Crystallographic Orientations of MgO Films Prepared by Plasma-Enhanced Metalorganic Chemical Vapor Deposition
Authors: Fujii Eiji , Tomozawa Atsushi , Fujii Satoru , Torii Hideo , Ryoichi Takayama Ryoichi Takayama , Takashi Hirao Takashi Hirao
Published: October 2002

Thin films of magnesium oxide (MgO) were prepared on glass substrates by plasma-enhanced metalorganic chemical
vapor deposition (PE-MOCVD) and the relationship between deposition conditions and crystallographic orientations were
studied. Highly crystalline and highly (100)-oriented MgO film was obtained at the vaporizing temperature of
210° C, O2 flow rate of 200 cm3· min-1, rf power of 400 W and
substrate temperature of 400° C. The orientation of MgO films is changed from (100) to (110) upon
increasing the vaporizing temperature from 210 to 240° C or upon decreasing the O2 flow rate from
200 to 50 cm3· min-1. These results indicated that the films deposited at the high arrival
ratios of oxygen to magnesium precursor (O/Mg) onto the substrate had a (100) orientation, while those deposited at
the low arrival ratios of O/Mg had a (110) orientation. The intrinsic stress of the (100) oriented film was tensile
and the magnitude was 0.25 GPa.
Patterning Characteristics of 0.1-µm Line-and-Space Pattern in Synchrotron Radiation Lithography
Authors: Somemura Yoh , Kimiyoshi Deguchi Kimiyoshi Deguchi , Kazunori Miyoshi Kazunori Miyoshi
Published: October 2002

A detailed analysis is performed to investigate the effects of mask contrast, mask-pattern size error and
proximity gap on resolution and exposure dose margin for replicating 0.1-µm-region
line-and-space (L&S) patterns using synchrotron radiation lithography. The analysis is performed by comparing Fresnel
diffraction simulation and pattern replication experiments. When a conventional-contrast (7) mask is used, designing
the pattern size of a Ta mask absorber to be slightly narrower than the specified value is a great advantage for
faithful pattern replication of 0.1-µm L&S patterns. A large dose margin is obtained for proximity
gaps of 15 µm or less. On the other hand, a low-contrast (2.5) mask has an advantage over the conventional
mask in that it allows the use of a larger proximity gap for replicating 0.1-µm L&S patterns. A
relatively large margin is obtained by limiting the Ta size error to the range of -0.05 µm to
+0.03 µm for proximity gaps smaller than 25 µm, and ±0.02 µm for a
30-µm gap.
Characterization of the Shallow and Deep Levels in Si Doped GaN Grown by Metal-Organic Vapor Phase Epitaxy
Authors: Hacke Peter , Maekawa Atsuyoshi , Koide Norikatsu , Kazumasa Hiramatsu Kazumasa Hiramatsu , Nobuhiko Sawaki Nobuhiko Sawaki
Published: October 2002

Si doped GaN with room temperature free carrier concentration 1.1× 1017 cm-3
studied using the Hall effect exhibits exponential carrier freeze-out over a large
range with activation energy 28.0± 0.5 meV; however, resistivity dependence on
temperature suggests carrier hopping occurs at low temperature. GaN with greater Si
concentration displays metallic impurity band conduction following the two-band model.
Deep level transient spectroscopy results show a negligible concentration of other deep
donors from native defects or unintentionally included impurities indicating that the
active shallow donor is uniquely Si; however, photoluminescence tests show broad yellow
emission with peak energy ∼ 2.2 eV commonly observed in Si doped GaN.
Development of Polycrystalline CuInxGa1-xSe2 Thin-Film Solar Cells with Band Gap of 1.3 to 1.5 eV
Authors: Kushiya Katsumi , Ohtake Yasutoshi , Yamada Akira , Konagai Makoto
Published: October 2002

Achievements in the development of CuIn

x

Ga1-
x

Se2 (CIGS)
thin-film solar cells with band gap of 1.3 to 1.5 eV to obtain a better match to the
solar spectrum are reported with efficiency over 10% on ZnO/CdS/CIGS thin film solar cells.
Our achievements are as follows: 13.5% efficiency with 44.5% Ga (band gap 1.32 eV)
and 10.7% efficiency with 81.5% Ga (band gap 1.57 eV, graded Ga structure). These
results clearly demonstrate (1) high efficiency over 13% is attainable with CIGS thin
films in the band-gap range of 1.3 to 1.5 eV and (2) the optimization of both buffer
and window layers is also one of the key issues in improving the efficiency. The defect
chemistry of a wide range of Cu–III–VI2 thin-film absorbers from CIS to CGS is
discussed based upon the analyses of PL spectra, PL peak positions and the film composition.
It is proposed for CIGS thin films that In
C
u
antisite donor defects be replaced with
Ga
C
u
antisite donor defects, increasing the fractional Ga content in the CIGS
thin films. The development on a ZnSe buffer layer which has a better lattice match to
CIGS thin films than CdS is also reported.
Contact Resistivity Dependence on Ge:Ni Ratio in AuNiAuGe Metallization on n-GaAs
Authors: Soo-Jin Chua Soo-Jin Chua , Seng Hin Lee Seng Hin Lee
Published: October 2002

It is found that the Ni:Ge ratio in AuGeNiAu metallization on n-GaAs determines the optimally low contact resistance condition independent of the Au layer thickness. In two series of experiments the thickness x of the Ni layer was varied in the structure Au/Ni/Ge/Au with layer thicknesses of 600/x/50/100 nm and 600/x/100/200 nm. Optimally low contact resistivity of 6.4×10-6 Ω cm2 and 1.68×10-5 Ω cm2, respectively, were obtained when the Ni:Ge layer thickness ratio reached 1. Secondary-ion mass spectroscopy showed that, at this Ni:Ge ratio of 1, maximum Ge doping on the n-GaAs was obtained. Such a condition is a result of a balance between the catalytic effect of Ni on the decomposition of GaAs by Au for effective doping by Ge, to achieve low contact resistance, and the formation of NiAs, rather than Ni2GeAs, under the excess-Ni condition, which results in an increase of contact resistivity.
AlxGa1-xAs/Si (x= 0–0.22) Tandem Solar Cells Grown by Metalorganic Chemical Vapor Deposition
Authors: Yang Mingju , Soga Tetsuo , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

Studies of Al

x

Ga1-
x

As/Si (x=0–0.22) tandem solar
cells have been carried out by using metal organic chemical vapor deposition (MOCVD).
The GaAs/Si tandem solar cell consists of a GaAs top cell with the Al0.3Ga0.7As
buffer layer and a Si bottom cell with the n+-p-p+ structure.
The theoretical analyses of the Si bottom cell are carried out for tandem solar cell
application. The suitable resistivity of the p-Si substrate for the Si bottom cell
has been found to be 10 Ω· cm, which corresponds to the experimental
results. The active-area conversion efficiency of 19.5% (1sun, AM0) for the GaAs/Si
tandem solar cell has been achieved in the three-terminal configuration. In the case of
the Al

x

Ga1-
x

As/Si tandem solar cell, x varies from 0.1 to 0.22.
The crystalline quality of the Al

x

Ga1-
x

As heteroepitaxial layer
grown on Si is improved, using a high-temperature growth process ( 800°C)
and thermal cycle annealings ( 300–900°C). The active-area conversion
efficiencies of 20.0% and 19.0% (1sun, AM0) for the Al0.15Ga0.85As/Si
tandem solar cell are obtained with four-terminal and two-terminal configurations, respectively.
Electrical and Optical Properties of Amorphous BaTiO3 Thin Films Grown by Metalorganic Chemical Vapor Deposition on Indium Tin Oxide-Coated Glass
Authors: Yoon Young Soo , Yoon Young Ku , Yom Sang Seop
Published: October 2002

In order to fabricate insulating films for a full-color thin-film electroluminescent
display, an amorphous BaTiO3 thin film was deposited on an indium tin oxide-coated
soda lime glass substrate at a low substrate temperature by metalorganic chemical vapor
deposition with use of Ba(tmhd)2, Ti(OC3H7)4 and N2O.
Scanning electron microscopy of the tilted surface of the as-grown BaTiO3
film showed a surface morphology of granular-like micrograins without defects such as
pinholes and clusters. The thickness of the as-deposited film was approximately 1400 Å
as confirmed by cross-sectional transmission electron microscopy. The formation of
an interface film between the as-grown film and the indium tin oxide was not observed.
Room-temperature frequency dependence of capacitance and dissipation factor was clearly
indicated those typically exhibited by the amorphous BaTiO3 capacitor deposited
on the conducting substrates having a metal-insulator-metal (MIM) structure. Optical
transmittance measurements showed that the amorphous BaTiO3 film deposited at 400°C
on the indium tin oxide-coated glass substrate has the transparency of about 80% in the
visible wavelength range. Furthermore, the value of the optical band gap was approximately
4.71 eV. These results indicate that the amorphous BaTiO3 thin film grown
on the indium tin oxide-coated glass can be used for thin-film flat panel electroluminescent display applications.