bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of CuInSe 2 Thin Films on Mo-Coated Glass Substrates by Pulse-Plated Electrodeposition
Authors: Shigetaka Nomura Shigetaka Nomura , Kazuhiko Nishiyama Kazuhiko Nishiyama , Kenji Tanaka Kenji Tanaka , Motoya Sakakibara Motoya Sakakibara , Masatoshi Ohtsubo Masatoshi Ohtsubo , Nobuyuki Furutani Nobuyuki Furutani , Saburo Endo Saburo Endo
Published: October 2002

CuInSe2 thin films are prepared on Mo-coated glass substrates by pulse-plated electrodeposition from an aqueous solution including CuCl2, InCl3 and SeO2.
Film deposition with a stoichiometric composition and a smooth surface has been achieved by the control of the applied pulses with a duty cycle θ of 33% and a cathode potential during on-time of -0.7 V vs the saturated calomel electrode (SCE).
The deposited films are annealed in nitrogen gas to be crystallized. The optimum annealing conditions have been determined using X-ray diffraction and Raman spectra measurement as: annealing temperature of 400°C, and annealing duration of 90 min.
Plasma Etch Void Formed at the SiC Film/Si Substrate Interface
Authors: Yong Sun Yong Sun , Tatsuro Miyasato Tatsuro Miyasato
Published: October 2002

Cubic silicon carbide films are grown on the Si (111) substrate by
means of hydrogen plasma sputtering. Formation mechanisms of the hollow
voids at the SiC film/Si substrate interface are studied by varying both
the film growth temperature from 650°C to 850°C, and the
film growth time from 2 s to 55 h. A two-step etching model is proposed
to explain the formation mechanisms, based on our experimental results.
The etching first starts from the point defects, and etch pits first
appear near the Si substrate surface. When this first etching stops due
to growth of a SiC film on the first etch pits, subseguent etching
starts around the first etch pits and results in the hollow voids at the
film/substrate interface at substrate temperatures above 650°C.
The depth of the hollow voids becomes constant with growth time after a
continuous SiC film is formed over the Si substrate.
Magnetic and Electrical Behaviors of Sr8V8O25
Authors: Kimishima Yoshihide , Ichiyanagi Yuko , Shimizu Kunihiko , Nagata Naruhisa , Mizuno Tatsuya
Published: October 2002

The DC magnetization M, AC magnetic susceptibility χ′ and χ′′, and
electrical resistivity ρ were measured for Sr8V8O25 polycrystals. The
magnetic susceptibility showed ferrimagnetic temperature dependence, and
the transition temperature T
C was estimated as 105 K. Below T
C, the steep
increase of magnetic susceptibility and the ferrimagnetic M–H curves were
observed. The peaks of χ′ and χ′′, and the visible splitting of the field cooled
magnetization (FCM) and zero field cooled magnetization (ZFCM)
appeared at T
p=57 K. These behaviors show the rapid increase of magnetic
relaxation time below T
p. The existence of a major M–H loop with a large
coercive force was assumed at 5 K from the positively shifted FCM–H loop
and small ZFCM, which also supported the above interpretation. The
temperature dependence of ρ was semiconductive above T
p with a slight
change of activation energy near T
C, while the hopping conductive behavior
and the current dependence of ρ appeared below T
p. The existence of
thermal hysteresis in ρ below T
p suggested that the magnetic and
electrical anomalies at T
p were induced by the structural phase transition
of Sr8V8O25.
Propagation Losses of Guided Waves in Metallized Sidewall Waveguides
Authors: Izutsu Masayuki , Wang Zhi Liang
Published: October 2002

A step-index planar waveguide sidewalled with metals is theoretically
studied by the effective refractive index method. Numerical results of
the geometrical and wavelength dispersions of the propagation losses and
the wavefunction profiles of the guided and the surface plasmon modes are
presented. The aim of this study is to investigate the possibility of
fabricating low-loss and small-size integrated optical waveguides or
circuits using the metallized sidewall structure.
Planarization of Film Deposition and Improvement of Channel Structure for Fabrication of Anti-Resonant Reflecting Optical Waveguide Type X-crossing Vertical Coupler Filter
Authors: Tak Chu Wugen Pan , Shinya Sato Shinya Sato , Tsuyoshi Maeda Tsuyoshi Maeda , Takashi Kato Takashi Kato , Yasuo Kokubun Yasuo Kokubun
Published: October 2002

To realize a low-sidelobe narrow-band Anti-resonant reflecting optical
waveguide (ARROW)-type vertical coupler filter,
the dependence of the refractive index and thickness profiles
of compound glass films,
deposited by a magnetron RF sputtering technique,
on the mixture ratio of Ar and O2 gases was investigated.
First, the depth profile of the refractive index of SiO2 films
was planarized using pure O2 gas.
Next, the lateral profiles of the refractive index and
thickness of compound glass films were planarized by
optimizing the gas mixture ratio of Ar and O2.
When the mixture ratio was Ar : O2 = 1 : 3,
the index variation of the Corning 7059 glass film was vastly
improved from 0.3% to 0.05%,
and the thickness variation was also improved from 9.0% to 4.0%.
A similar improvement was also achieved for SK1 glass (from SCHOTT)
and the Ta2O5–SiO2 binary glass system.
A low sidelobe ARROW-type vertical coupler filter (VCF)
with Corning 7059 glass and SK1 glass cores was demonstrated,
using these deposition techniques and a wet chemical etching technique.
In addition, the planarization technique of
stripe-lateral-confinement (SLC)-ARROW waveguide was developed
using a lift-off technique.
A narrow band ARROW-type vertical coupler filter
with Ta2O5–SiO2 cores was achieved by the
lift-off and reactive ion etching (RIE) techniques.
Optical Module Using Double-Sided Polarizing Diffractive Optical Element for Digital Versatile Disc Drives
Authors: Nagano Tsuyoshi , Shirakawa Hidekazu , Katayama Ryuichi , Yamanaka Yutaka
Published: October 2002

Digital versatile discs (DVDs) promise to provide excellent multimedia storage for
both entertainment and computer use. In this paper, we report a newly designed
optical module for use in DVD systems. It consists of a laser diode chip, a
photodiode chip, a compound prism, and a double-sided polarizing diffractive optical
element (DOE). The double-sided polarizing DOE provides high total light power
efficiency (here 78%) that a DVD system requires because of its very small
operational margin. The developed optical module has dimensions 9.5 mm(W)×4.2
mm(D)× 6.7 mm(H) and weighs 0.55 g. Its practicality has been demonstrated in
successful DVD readout operations, and it is expected to provide the same compact,
inexpensive drive that optical modules provide in compact disc (CD) systems.
Fine Surface Images That Reflect Cytoskeletal Structures in Cultured Glial Cells by Atomic Force Microscopy
Authors: Yukako Yamane Yukako Yamane , Dai Hatakeyama Dai Hatakeyama , Takuro Tojima Takuro Tojima , Kazushige Kawabata Kazushige Kawabata , Tatsuo Ushiki Tatsuo Ushiki , Shigeaki Ogura Shigeaki Ogura , Kazuhiro Abe Kazuhiro Abe , Etsuro Ito Etsuro Ito
Published: October 2002

The morphology of cultured glial cells was examined using a combination of atomic force microscopy (AFM) and immunofluorescence staining for cytoskeletons. The meshwork of type-1 astrocytes consisted of thick longitudinal and thin lateral lines on the cell surfaces observed by AFM; the former lines were confirmed to be reflections of actin filaments. The astrocytic processes of type-2 astrocytes were observed to be rugged on AFM. These structures were mainly affected by microtubules. Immunofluorescence imaging of microglia revealed that actin filaments and microtubules were arranged radially and wavily along the cell edge, respectively. AFM could detect these radial and wavy structures clearly. These results show that AFM can provide information on the cytoskeletons of glial cells, indicating that AFM is a useful tool for the morphological characterization of cells.
Characteristics of Mg-Doped GaN and AlGaN Grown by H2-Ambient and N2-Ambient Metalorganic Chemical Vapor Deposition
Authors: Sugiura Lisa , Suzuki Mariko , Nishio Johji , Itaya Kazuhiko , Kokubun Yoshihiro , Ishikawa Masayuki
Published: October 2002

The characteristics of Mg-doped GaN and AlGaN grown by H2-ambient and N2-ambient
metalorganic chemical vapor deposition are compared and discussed. While as-grown Mg-doped
GaN and AlGaN grown under H2-ambient show high resistivity, p-type GaN and AlGaN
with high acceptor concentration were obtained by N2-ambient growth without any
post-treatment. The hydrogenation process of the Mg acceptor and the dissociation process of
hydrogen atoms from Mg–H complexes might occur simultaneously in the case of N2-ambient
growth. The films grown under N2-ambient were clearly shown to have superior characteristics
in uniformity and reproducibility to those grown under H2-ambient, since the characteristics of
the films grown under N2-ambient are steady over the wide range of growth temperature. Our
results indicate that the N2-ambient growth is suitable for the mass production of GaN-based
light-emitting devices in the respects that the device fabrication process can be simplified and
that the uniformity and the reproducibility of the layer properties are greatly improved.
Comparison of N2 and NH3 Plasma Passivation Effects on Polycrystalline Silicon Thin-Film Transistors
Authors: Lee Yeong-Shyang , Lin Hsiao-Yi , Lei Tan-Fu , Huang Tiao-Yuan , Chang T.-C. , Chang Chun-Yen
Published: October 2002

The passivation effects of pure N2 plasma on polycrystalline silicon (poly-Si) thin-film
transistors (TFTs) have been studied and compared with those of NH3 plasma. We found
that, similar to the recently-proposed NH3 plasma passivation, N2 plasma passivation can also
effectively improve device parameters such as field effect mobility, threshold voltage,
subthreshold swing, off current, and on/off current ratio. While the improvement of NH3-passivated devices can be attributed to both hydrogen and nitrogen passivation effects,
nitrogen passivation alone is mainly responsible for the improvement of N2-passivated devices.
In addition, we found that N2-passivated devices exhibit much better hot-carrier reliability
than NH3-passivated devices. The better hot-carrier reliability of N2-passivated devices can
be explained by the formation of strong Si–N bonds which are difficult to break, while
effectively eliminating the weaker N–H bonds, which are inevitable in NH3-passivated devices.
The results of a Fourier transform infrared (FTIR) spectrum analysis performed in this study
are consistent with this proposition.
Effects of Back-Channel Etching on the Performance of a-Si:H Thin-Film Transistors
Authors: Ando Masahiko , Wakagi Masatoshi , Minemura Tetsuroh
Published: October 2002

Thickness of the a-Si:H layer in the back-channel etched thin film transistor (TFT) was
successfully reduced to less than 100 nm, with an accompanying increase in the field effect
mobility. The thinning was realized by reducing surface defects of the a-Si:H layer generated in
the back-channel overetching step. The relationships between the TFT performance and surface
defects, analyzed by spectroscopic ellipsometry, were investigated as a function of a-Si:H thickness
and back-channel etching depth.
Electrical Characteristics of SrBi2Ta2O9 Capacitor after Aluminum Metallization
Authors: Furuya Akira , Amanuma Kazushi , Maejima Yukihiko
Published: October 2002

The electrical characteristics of ferroelectric SrBi2Ta2O9 capacitors, after patterning Al interconnects on them, were investigated to determine the causes of the characteristic degradation
occurring with metallization. The Al interconnect structures were patterned using various Al etching times (overetching: 5, 30, 60, and 75%) and etching methods (ion milling and reactive ion etching (RIE)).
The current–voltage (I–V ) characteristics degraded significantly although the capacitors were covered with a Pt top electrode and interdielectric SiO2.
It was found that overetching is the dominant factor responsible for the degradation of the I–V characteristics occurring with metallization. Stress in the ferroelectric film and charge-up effects
were also investigated as causes of degradation by bending wafers and cutting off the neutralizer during ion-milling, but it was found that neither of these were significant causes of degradation. Furthermore,
uniform I–V characteristics with very slight degradation were obtained by cutting off the neutralizer. Recovery of the degradation was attempted by annealing
in N2 ambient, but no improvement in the I–V characteristics of the capacitors was obtained.
Preparation and Structure of Al(Sr, Ca)2HoCu2O7 and AlSr2(Ho, Ca)Cu2O7 Cuprates
Authors: Ono Akira , Mao Jianfu , Horiuchi Shigeo
Published: October 2002

Chemical composition, lattice parameters and superstructure of the
Al-1212 cuprates are studied for samples with nominal compositions
AlSr2R1-x
Ca
x
Cu2O7 (R=Y or Ho) by energy dispersive X-ray analysis,
powder X-ray diffraction and electron microscopy. It is found that the
replacement of Ho by Ca occurs predominantly at 2 GPa, whereas the
substitution of Sr by Ca occurs at ambient pressure. All the Ca-containing Al-1212 cuprates examined show a superstructure similar
to that of AlSr2YCu2O7. The fundamental framework structure does not
depend on x.
Preparation and Electronic Properties of YBa2Cu3OxFilms with Controlled Oxygen Stoichiometries
Authors: Kaung-Hsiung Wu Kaung-Hsiung Wu , Ming-Chih Hsieh Ming-Chih Hsieh , Shih-Pu Chen Shih-Pu Chen , Shyh-Chin Chao Shyh-Chin Chao , Jenh-Yih Juang Jenh-Yih Juang , Tseng-Ming Uen Tseng-Ming Uen , Yih-Shung Gou Yih-Shung Gou , Tseung-Yuen Tseng Tseung-Yuen Tseng , Chao-Ming Fu Chao-Ming Fu , Jin-Ming Chen Jin-Ming Chen , Ru-Gun Liu Ru-Gun Liu
Published: October 2002

We describe a novel technique capable of controlling the oxygen content of YBa2Cu3Ox(YBCO) films in a precise and reversible manner. The temperature dependence of resistivity and the distinct two-plateau behavior in critical temperatureTcoversus oxygen content plot of these films are consistent with those observed in the bulk and single crystals of YBCO. The O 1sand Cu 2pabsorption spectra of these films were measured by polarization-dependent X-ray absorption spectroscopy (XAS). The intensity variations of the pre-edge peaks as a function of oxygen content are discussed. We also used these films to systematically study the electron-phonon coupling strength and the position of Fermi level by using a femtosecond pump-probe technique. A clear sign-reversal of the transient reflectivity, which was consistently explained by the thermomodulation model, was observed. Both of these optical measurements support the idea that the electronic structure of YBCO cuprates is based on the charge transfer model with hybridization between the Cu and O sites.
Electrical Properties of Pt/SrBi2Ta2O9/CeO2/SiO2/Si Structure for Nondestructive Readout Memory
Authors: Suk Shin Dong , Nyung Lee Ho , Tae Kim Yong , Hoon Choi In , Ho Kim Byong
Published: October 2002

Memory window and leakage current density of Pt/SrBi2Ta2O9/CeO2/SiO2/Si structure have been investigated for non destructive read out memory. Coercive field that decisively affects on the memory window becomes greater by the interposition of the CeO2 insulator between SrBi2Ta2O9 and SiO2 and thus the memory window also increases with an electric field to the SrBi2Ta2O9. A typical value of memory window for Pt/SrBi2Ta2O9(140 nm)/CeO2/SiO2/Si is in the range of 0.5 – 3.0 V, which is high enough for the non destructive read out memory, at the applied voltage of 3 – 9 V. The leakage current density is remained at 3 ×10-8 A/cm2 until the applied voltage increases up to 10 V.
Poled Polymer Etalon Light Modulator on Integrated Circuits
Authors: Harada Kenji , Munakata Katsuhiro , Itoh Masahide , Yoshikawa Nobukazu , Yonezu Hiroo , Umegaki Shinsuke , Yatagai Toyohiko
Published: October 2002

Electrically addressed reflective spatial light modulators with polymeric thin
films are fabricated on the surface of an n-type metal-oxide-semiconductor (NMOS)
chip. The use of a resonator structure is proposed to minimize the driving voltage. The
developed device is composed of 1×5 NMOS transistors and nonlinear polymeric
materials sandwiched between aluminum electrodes. The electrooptical polymer
consists of disperse red 1 (DR1)-doped poly-methyl-methacrylate (PMMA). Poling was
demonstrated on this chip and the light modulation was observed using a lock-in
amplifier. A modulation efficiency of 2.0 × 10-5 was obtained.
Thermal Contraction of Drawn Polyethylene Film I. An Empirical Equation for Temperature Dependence of Thermal Stress
Authors: Tanaka Yutaka , Nakanishi Hirohide , Saeki Susumu , Yamaguchi Takuji
Published: October 2002

Thermal stress and strain were measured during heating from 30°C to 100°C
for drawn polyethylene films of various draw temperatures and ratios. Behavior of
thermal strain was classified into three types, and discussed in terms of structural
change in polymer chains during the drawing process. The Arrhenius plot was
constructed for the temperature dependence of thermal strain, and an inflection point
was observed in the plot over the temperature range studied. Temperature
dependence of thermal stress showed the maximum value, which increased with draw
ratio. An empirical equation for the behavior of thermal stress is derived using
Boltzmann's superposition principle. Good agreement was found between calculated
and measured values of thermal stress.
Phase-Transitional Behavior in Vinylidene Fluoride-Trifluoroethylene Copolymer Crystals under Elevated Pressures
Authors: Itoh Takashi , Matsuda Hidehiro , Shibata Hiroyuki , Maeda Kazuhiko , Hashimoto Masato
Published: October 2002

Temperature dependence of d
200,110-spacing in vinylidene fluoride (VDF)-trifluoroethylene
copolymer crystals with VDF molar contents of 65 and 57% is measured at 0.1, 100,
200 and 300 MPa. In the crystal with 65% of VDF, continuous structural change
transforms into the first-order phase transition at 300 MPa, suggesting a critical point in
the P–T phase diagram of the crystal. Such phenomena is attributed to a decrease in the
intermolecular distance with pressure, affecting the intermolecular Lennard-Jones
potential to a greater extent than the electrostatic interaction.
Removal of Surface Oxides on Copper by Pulsed Laser Irradiation
Authors: Yonezawa Yasuto , Minamikawa Toshiharu , Morimoto Akiharu , Shimizu Tatsuo
Published: October 2002

The removal of an oxide layer from a copper surface by pulsed laser
irradiation was studied to improve the soldering property of Sn–Pb. The copper
surface was irradiated by ArF excimer laser or the second harmonic pulsed
Nd3+:YAG (532 nm) laser. It was found that the thin surface oxide layer can be
removed by laser irradiation even in air without degradation of the copper surface
layer. However, highly intense irradiation causes significant changes in the
surface morphology, resulting in the reduced wettability for the Sn–Pb solder.
Interdiffusion in (Pb1-xLax)(ZryTi1-y)1-x/4O3/SrRuO3 Multilayer Thin Films Examined by Secondary Ions Mass Spectroscopy
Authors: Ling Yong-Chien , Lee Jih-Hsin , Liu Kuo-Shung , Tseng Tzu-Feng , Tseng Yung-Kuan , Lin I-Nan
Published: October 2002

The interdiffusion between layers in multilayer thin films, including
(Pb0.97La0.03)(Zr0.66Ti0.34)0.9875O3 (PLZT), SrRuO3, Ru, Pt and Si, was examined using
secondary ions mass spectroscopy (SIMS). The PLZT thin films deposited on Pt-coated
Si-substrate using SrRuO3 as buffer layer possessed ferroelectric properties
substantially superior to those grown on Si (or Si3N4) surface. Procoating Ru-layer
prior to the deposition of SrRuO3 layer further improved the electrical response of
PLZT thin films, that was ascribed to the efficient suppression of Sr- and Ru-outward
diffusion into PLZT materials. The optimum properties attained are remanent
polarization P
r=25.6 µC/cm2, coercive force E
c=47.1 kV/cm, relative dielectric
constant K=1,200 and leakage current <10-5 A/cm2 (under 50 kV/cm).
Growth and Properties of CNx Films Prepared by Reactive DC Magnetron Sputtering
Authors: Jin Yun-Sik , Matsuda Yoshinobu , Fujiyama Hiroshi
Published: October 2002

Carbon nitride (CN
x
) films have been deposited by reactive sputtering of a graphite
target with nitrogen and/or argon gases. A modified cylindrical DC magnetron was used as a
sputter deposition source and the processing plasma was monitored by means of both a
Langmuir probe and optical emission spectroscopy (OES). The nitrogen to carbon ratio (N/C
ratio) evaluated by X-ray photoelectron spectroscopy (XPS) ranged from 0 to 0.5. Strong
correlation between N/C ratio in the film and N2
+ /N2
* emission intensity ratio was confirmed
from the result of the OES study. An absorption band near 2200 cm-1 in the Fourier transform
infrared (FT-IR) spectra strongly indicated the existence of C≡N covalent bonding.
Transmission electron microscopy (TEM) bright-field imaging revealed that the prepared CN
x

film contained nanocrystallines buried in the amorphous background and the observed grain
size was 10–60 nm range.
Preparation of Ultrafine Crystalline TiO2 Powders from Aqueous TiCl4 Solution by Precipitation
Authors: Nam Hee-Dong , Lee Byung-Ha , Kim Sun-Jae , Jung Chung-Hwan , Lee Ju-Hyeon , Park Sung
Published: October 2002

Ultrafine crystalline TiO2 powders were prepared by just heating and stirring
aqueous TiOCl2 solution with a Ti+4 concentration of 0.5 mol/l at room
temperature to 100°C under one atmosphere. The crystallinity, the phase
transformation and the particle shape of ultrafine TiO2 powders obtained by
this simple precipitation method were analyzed using an X-ray diffractometer
(XRD), transmission electron microscopy (TEM), differential thermal analyzer
(DTA), and scanning electron microscopy (SEM). TiO2 crystalline precipitates
with a pure rutile phase were formed below 65°C, then TiO2 crystalline
precipitates with an anatase phase started forming at temperatures higher than
65°C, which ends with the pure anatase phase at 100°C. The direct formation
of TiO2 crystalline precipitates from an aqueous TiOCl2 solution is due to the
existence of the OH- ions in distilled water which cause the crystallization of
TiOCl2 to TiO2 without hydrolyzation to Ti(OH)4. Conventionally, rutile-phase
TiO2 is obtained at much higher temperatures. However, in this study a stable
rutile-phase TiO2 was obtained by a simple method at close to room
temperature.
Investigation of Positron Moderator Materials for Electron-Linac-Based Slow Positron Beamlines
Authors: Suzuki Ryoichi , Ohdaira Toshiyuki , Uedono Akira , Cho Yang Koo , Yoshida Sadafumi , Ishida Yuuki , Ohshima Takeshi , Itoh Hisayoshi , Chiwaki Mitsukuni , Mikado Tomohisa , Yamazaki Tetsuo , Tanigawa Shoichiro
Published: October 2002

Positron re-emission properties were studied on moderator materials in order to improve the positron moderation system of electron-linac-based intense slow positron beamlines. The re-emitted positron fraction was measured on tungsten, SiC, GaN, SrTiO3, and hydrogen-terminated Si with a variable-energy pulsed positron beam. The results suggested that tungsten is the best material for the primary moderator of the positron beamlines while epitaxially grown n-type 6H–SiC is the best material for the secondary moderator. Defect characterization by monoenergetic positron beams and surface characterization by Auger electron spectroscopy were carried out to clarify the mechanism of tungsten moderator degradation induced by high-energy electron irradiation. The characterization experiments revealed that the degradation is due to both radiation-induced vacancy clusters and surface carbon impurities. For the restoration of degraded tungsten moderators, oxygen treatment at ∼900°C is effective. Furthermore, it was found that oxygen at the tungsten surface inhibits positronium formation; as a result, it can increase the positron re-emission fraction.
Submilliwatt Continuous-Wave Coherent Light Generation near 214.5 nm by Two-Stage Frequency Doubling of a Diode Laser
Authors: Matsubara Kensuke , Tanaka Utako , Imajo Hidetsuka , Watanabe Masayoshi , Urabe Shinji
Published: October 2002

We generated 0.64 mW of continuous-wave coherent light near 214.5 nm
by using an all-solid-state light source. In this source, IR light from a
master-laser and power-amplifier system based on diode lasers was frequency-quadrupled in two successive frequency-doubling stages. A continuous
frequency-scanning range of more than 7 GHz was observed in the 214–215 nm
wavelength region.
Thickness-Dependent Orientation of the Pendant Phenyl Group at the Surface of Polystyrene Thin Films
Authors: Ueno Nobuo , Azuma Yasushi , Tsutsui Masahiko , Okudaira Koji , Harada Yoshiya
Published: October 2002

This paper reports on experimental evidence showing that the take-off angle dependence of the photoelectron intensity from the top π band of a polystyrene thin film, originating from the pendant phenyl group, depends on the film thickness. The result indicates that the orientation of the phenyl group at the film surface changes with the film thickness. Theoretical analysis of the observed angular distribution using the single scattering approximation combined with molecular orbital calculation (SS/MO) showed that the phenyl groups at the film surface become perpendicular oriented for a
thicker film. The present finding suggests the possibility that the surface property of a thin film of a pendant group polymer can be controlled by changing the film thickness.
Atomic Layer Deposition of TiN Films by Alternate Supply of Tetrakis(ethylmethylamino)-Titanium and Ammonia
Authors: Min Jae-Sik , Son Young-Woong , Kang Won-Gu , Chun Soung-Soon , Kang Sang-Won
Published: October 2002

Atomic layer deposition (ALD) of amorphous TiN films on SiO2 between 170°C and 210°C
has been investigated by alternate supply of reactant sources, Ti[N(C2H5CH3)2]4
[tetrakis(ethylmethylamino)titanium:TEMAT] and NH3. Reactant sources were injected into
the reactor in the following order:TEMAT vapor pulse, Ar gas pulse, NH3 gas pulse and Ar gas
pulse. Film thickness per cycle was saturated at around 1.6 monolayers (ML) per cycle with
sufficient pulse times of reactant sources at 200°C. The results suggest that film thickness per
cycle could exceed 1 ML/cycle in ALD, and are explained by the rechemisorption mechanism
of the reactant sources. An ideal linear relationship between number of cycles and film
thickness is confirmed. As a result of surface limited reactions of ALD, step coverage was
excellent. Particles caused by the gas phase reactions between TEMAT and NH3 were almost
absent because TEMAT was segregated from NH3 by the Ar pulse. In spite of relatively low
substrate temperature, carbon impurity was incorporated below 4 at.%.
Debris from High-Aspect-Ratio Rectangular Focused Laser Irradiation on a Tape Target Surface in an X-Ray Laser System
Authors: Hisada Yoshiyuki , Abraha Petros , Takamoto Kiichi , Yamaguchi Naohiro , Hara Tamio
Published: October 2002

This study measures the distribution of debris ejected from an aluminum tape target subjected to laser
irradiation. The irradiation area is rectangular with a high aspect ratio of 67. The power density of the laser
beam is 8×1010 W/cm2 at the irradiation surface. The ejected debris is collected on a plane parallel to the target surface. The angular distribution of debris thickness in the direction parallel to the longer side of the
irradiation area is cos
60θh. Similarly, the angular distribution of debris thickness in the direction parallel to the shorter side of the irradiation area is cos
5θv, where the angles θh and θv are deviations from the irradiation surface normal in the horizontal and vertical directions, respectively. An additional feature is the sacrificial film feed mechanism designed to shield the laser beam entrance window from debris deposition. Based on the angular distribution of debris thickness, the film feed rate is adjusted to ensure delivery of the required beam energy at the target surface.
Azimuth Dependence of Solar Radiation on Inclined Surfaces
Authors: Shibata Noboru
Published: October 2002

In general, the daily variation pattern of global solar radiation on an inclined surface is estimated by assuming the symmetrical daily variation of global
solar radiation. The author carried out an experiment to examine the azimuth dependences of solar radiation on an inclined surface. In the experiment, the
amount of solar radiation was found to be greater on a westward-facing surface
than on an eastward-facing surface throughout the year.
Low-Temperature Synthesis of SrBi2Ta2O9 Ferroelectric Thin Films through the Complex Alkoxide Method: Effects of Functional Group, Hydrolysis and Water Vapor Treatment
Authors: Kato Kazumi
Published: October 2002

SrBi2Ta2O9 (SBT) ferroelectric thin films were synthesized at lower temperatures by the sol–gel method using complex alkoxides. The effects of the complex alkoxide functional group, the amount of water used in hydrolysis, and a mixture of water vapor and oxygen flow
during calcination, on the crystallization, the microstructural development, and the ferroelectric properties of the SBT thin films were addressed. The film which was deposited from complex alkoxide solutions and then calcined at 250°C in the
mixture, contained a relatively smaller amount of the remaining alkoxy groups, and therefore, crystallized to SBT via rapid thermal annealing at temperatures below 500°C in an oxygen flow. Crystallinity
improved significantly and the microstructure was able to develop up to 650°C. Remarkable grain growth was observed particularly in the SBT thin film deposited from the ethanolic solution of the complex
ethoxide. Film annealed at 650°C exhibited the saturated P–E hysteresis loop and improved endurance behavior.
Synthesis of Highly Oriented Tungsten Bronze K(Pb0.6Ba0.4)2Nb5O15 Thin Films by the Chemical Solution Deposition Method
Authors: Sakamoto Wataru , Kosugi Kana , Yogo Toshinobu , Hirano Shin-ichi
Published: October 2002

Crack-free K(Pb0.6Ba0.4)2Nb5O15 (KPBN60) thin films have been synthesized
by the chemical solution deposition method. A homogeneous and
stable precursor solution could be prepared by controlling the reaction
of metal-organic compounds in 2-methoxyethanol. KPBN60 precursor
powder crystallized in the tungsten bronze phase above 700°C. KPBN60
thin films on MgO(100) and Pt(100)/MgO(100) also crystallized in the
tungsten bronze phase with preferred c-axis orientation. Two crystal
lattice planes of KPBN60 were intergrown at an orientation of 18.5° on
MgO(100) and Pt(100)/MgO(100) substrates. The KPBN60 thin films on
Pt(100)/MgO(100) substrates exhibited typical ferroelectric P-E hysteresis loops.
Lifetime and Degradation Mechanism of Multilayer Ceramic Actuator
Authors: Thongrueng Jirawat , Tsuchiya Toshio , Nagata Kunihiro
Published: October 2002

The lifetime and degradation mechanism of the multilayer ceramic actuator (MCA) were studied. The effects of temperature, humidity and load on the lifetime of the MCA under high DC or 50 Hz unipolar AC voltages are discussed. The logarithm
of the lifetime had a linear relationship with the logarithm of the electric field. The lifetime decreased as the applied voltage was increased, along with increased
temperature and humidity. The main causes of MCA degradation were concluded to be vibration and isolated destruction.
Durability Properties of Piezoelectric Stack Actuator
Authors: Sakai Takenobu , Kawamoto Hiroshi
Published: October 2002

Changes of temperature were measured for stack actuators having various values of E
c and
bending strength. The increase of temperature was 75°C in the center of low E
c stack for a
starting environment temperature of 120°C with 130 Hz driving frequency. The low E
c Stack
exhibited 30% degradation in displacement after 107 cycles which was caused by self-heating.
K
p, displacement and bending strength decreased at the pellets near the center of low E
c stack
after 107 cycles testing. These deteriorations were caused by decrease of part of the domain
rotation. Change in properties of decomposed pellets from high E
c stack appeared less
compared with the low E
c stack. It seems that E
c value has a strong influence on durability
compared to bending strength.
Fundamental Limitations to the Viewing Angle of Liquid Crystal Displays with Birefringent Compensators
Authors: Stallinga S. , Eerenbeemd J. M. A. van den , Haaren J. A. M. M. van
Published: October 2002

The limited viewing angle of twisted nematic (TN) active matrix liquid crystal displays is a major problem for applications in e.g. desk-top monitors. The range of viewing angles with acceptably displayed images can be extended by adding birefringent compensation layers to the display. Here it is shown that there are fundamental limitations to the viewing angle range that can be achieved in this way. It may turn out for a particular viewing angle that, (a) grey scale inversion cannot be remedied, and (b) increase of contrast leads to decrease of brightness. The existence of these limitations can be proven by analyzing the change in polarization of light propagating through the display. The vertical viewing angle range of the TN-effect suffers from both limitations. These limitations do leave significant room for improvement by using compensators. The horizontal viewing angle range is not fundamentally limited at all.
Simulation of the Piezoelectric Effect on the Device Characteristics of AlGaN/GaN Insulated-Gate Heterostructure Field Effect Transistors
Authors: Imanaga Syunji , Kawai Hiroji
Published: October 2002

The piezoelectric effect (PE) on the device characteristics due to lattice
mismatch in the heterostructure was simulated by solving Poisson and
Schrodinger equations self-consistently for GaN-based field effect transistors
(FET). By comparing the simulation results obtained with and without PE,
we found the following. (1) PE shifts the threshold voltage (V
th) of FET; this
V
th shift widens the flat region in transconductance–gate voltage (G
m–V
gs)
and cutoff frequency–gate voltage (f
T–V
gs) characteristics. (2) G
m is higher
with PE than without PE, while f
T values are nearly the same for both with
and without PE. (3) The equilibrium two-dimensional channel electron gas
(2DEG) concentration (N
ch) increases considerably with PE. This 2DEG
concentration greatly reduces the parasitic resistance between the gate and
the source/drain. We concluded that PE improves FET performance, and
we determined the optimal FET structure with PE from the viewpoint of
charge control.
Analysis of the Influence of Carrier Scattering in the Channel of a Metal/Insulator Tunneling Field Effect Transistor
Authors: Wataru Saitoh Wataru Saitoh , Katsuyuki Yamazaki Katsuyuki Yamazaki , Masafumi Tsutsui Masafumi Tsutsui , Masahiro Asada Masahiro Asada
Published: October 2002

A tunneling field effect transistor
using CoSi2/Si/CdF2/CaF2 heterostructures
on a Si substrate is theoretically studied.
It is controlled by the electric field from the gate bias
and saturation characteristics are expected
even with a 5-nm-long channel.
In the tunneling field effect transistor,
carrier density in the channel increases
when electrons tunneling from source to channel
are scattered in the channel.
Therefore, the transconductance and the transit velocity of
electrons in the channel decrease.
As a result, the cut-off
frequency of the device decreases.
A theoretical analysis shows that
the cut-off frequency of a tunneling field effect transistor with
a 5-nm-long channel is reduced by a factor of two
compared to the value without scattering,
when all the tunneling electrons are
scattered in the channel.
Resonant Detection and Mixing of Terahertz Radiation by Induced Base Hot Electron Transistors
Authors: Victor Ryzhii Victor Ryzhii
Published: October 2002

The harnessing of induced base hot electron transistors (IBHETs)
with high mobility of electrons in the base
as detectors and mixers of electromagnetic radiation in the range of terahertz
frequencies is proposed. The theory of physical effects associated with the
operation of detectors and mixers based on IBHETs is developed.
It is shown that the resonant excitation of the standing plasma waves in
the IBHET base is possible under the influence of high-frequency
electromagnetic signals. At resonant frequencies the amplitude of the base
potential oscillation significantly exceeds the amplitude of incoming signals
provided the electron mobility is high enough. This results in the IBHET
responsivity at resonant frequencies much higher than that of Schottky diodes.
For IBHETs with micrometer or near submicrometer
lateral sizes the resonant frequencies fall into the terahertz range.
The resonant frequencies are tuned by biasing voltages.
Measurement of Spherical Aberration Utilizing an Alternating Phase Shift Mask
Authors: Nakao Shuji , Nakae Akihiro , Sakai Junjirou , Miura Tamaki , Tatsu Shin-ichirou , Tsujita Kouichirou , Wakamiya Wataru
Published: October 2002

A spherical aberration function is measured utilizing an
alternating phase shift mask (PSM). First, it is theoretically
considered that with a highly coherent illumination, the focus of
the alternating phase shift lines and spaces (L/S) pattern is
equivalent to that of rays in a small annular area of the reference
sphere when the aberration function is axially symmetric in the
sphere. Then, the focus variation with the pattern pitch is
obtained by a printing experiment that employs an alternating PSM.
After a primitive mathematical operation, the aberration function is
obtained from the experimentally observed focus variation. The
aberration function is examined by investigating various anomalous
phenomena observed in the printing with the various resolution
enhancement techniques (RETs). The comparison between the
experimentally observed phenomena and the predictions based on the
calculated images with the measured aberration functions shows fair
agreement. Consequently, the validity of this measurement method is
confirmed.
Nondestructive Magnetic Detection of Plasticized Area Using Superconducting Quantum Interference Device
Authors: Kasai Naoko , Chinone Kazuo , Nakayama Satoshi , Odawara Akikazu , Yamakawa Hiroshi , Ishikawa Noboru
Published: October 2002

The relationship between the magnetic and structural changes induced by the application of a
tensile load to a carbon steel specimen was investigated by correlating the change in the spatial
second-order gradient component of the magnetic flux density d2
B

z
/dr
2 with the appearance of the Lüders bands on the specimen surface. The magnetic change was measured using a
nondestructive evaluation (NDE) system with a concentric second-order superconducting
quantum interference device (SQUID) gradiometer of low temperature superconductor. The area
where peaks and folds appeared in the 3-dimensional map of d2
B

z
/dr
2 corresponded to the area
where Lüders bands appeared on the specimen surface. The dimensions of the area where peaks
and folds appeared had a strong correlation with the residual strain of the specimen. It was
concluded that the magnetic NDE using SQUID has the ability to detect the area plasticized by fine
deformation in ferromagnetic materials.
Effects of Annealing on the Magnetic Properties and Structures of Sputtered Co–Pt Alloy Thin Films
Authors: Yamamoto Tomoo , Tezuka Tetsuya , Nishimaki Makio , Ishiguro Takashi
Published: October 2002

The effects of annealing on the in-plane coercivity and the crystal structure have
been investigated for sputtered Co–Pt alloy thin films with Pt content between 0 and 50 at.%. The coercivity of a Co50Pt50 film drastically increases at annealing temperatures above 800 K. The coercivity increase corresponds to the formation of an L10 ordered phase, which is
formed by the annealing at 940 K in less than 1 h. A maximum coercivity of 920 kA/m
(11.5 kOe) is more than that reported for a bulk Co–Pt alloy. The grain size drastically
increases in the early stage of annealing. (The grain size should be decreased for the use of
the Co–Pt films as high-density recording media.)
Characteristics of Deuterium-Loaded Fiber Bragg Gratings
Authors: Wang Lon A. , Hsu Chih Wei , Chen Hsuen Li
Published: October 2002

Fiber Bragg gratings with controllable reflectance and bandwidth were
fabricated by employing high-pressure deuterium loading for photosensitivity
enhancement and by utilizing a phase mask for holographic exposure. The
absorption peak near 1.71 µm was used as an indicator to monitor the evolution
of deuterium diffusion into and out of the fiber, and it was noted that the
measured results were consistent with the simulated ones. Thermal hysteresis of
the fiber Bragg grating was markedly reduced and reliability was therefore
increased, following annealing. The difference between hydrogen and deuterium
loadings is also discussed.
Forces of a Single-Beam Gradient-Force Optical Trap on Dielectric Spheroidal Particles in the Geometric-Optics Regime
Authors: Shima Kotaro , Omori Ryota , Suzuki Atsuyuki
Published: October 2002

We developed a computational code to calculate the forces of a single-beam gradient-force optical trap exerted on dielectric ellipsoidal particles in the geometric-optics regime. Using this code, the axial and the transverse trapping stability of spheroidal particles, the semi-major axis of which is perpendicular (type-A) and parallel (type-B) to an incident beam axis, was evaluated and the effects of the nonspherical geometry of the particles were analyzed. As the fractional deformation ratio increased, the axial trapping stability improved for type-B particles, whereas it degraded for type-A particles. It can, therefore, be concluded that type-B particles can be trapped more stably than type-A particles. It was also observed that the axial trapping stability can be improved by the use of a TEM01
*-mode beam instead of a TEM00-mode beam.
Crystallographic, Dielectric and Piezoelectric Properties of PbZrO3–PbTiO3 System by Phenomenological Thermodynamics
Authors: Yamamoto Takashi
Published: October 2002

Spontaneous polarization, P
s, dielectric constant, ε
s, and
piezoelectric constant, d

i
j
, at a given composition and
temperature were calculated for all compositions of the
Pb(Zr1-x
Ti
x
)O3 system using phenomenological thermodynamics
and compared with experimental data by considering the domain
effect. In the calculated phase diagram, the first-order phase
transition in compositions close to PbZrO3 and PbTiO3, the
second-order phase transition in all compositions except those
close to PbZrO3 and PbTiO3, and the morphotropic phase
boundary between rhombohedral and tetragonal phases could be
distinctly observed. The calculated phase diagram was in good
agreement with the available experimental data.
Micro Free-Form Fabrication of Aluminum Nitride and Zinc Oxide
Authors: Otake Naoto , Liu Lisheng , Yasuhara Toshiyuki , Kato Kazunori
Published: October 2002

Selective growth of aluminum nitride (AlN) and zinc oxide (ZnO) has been performed by an Ar-laser-enhanced reactive vapor deposition method on Si (100) substrates. The substrate was selectively heated by laser irradiation. Al and Zn were evaporated from Ta crucibles by an electron gun in NH3 and O2 atmospheres, respectively. The metal vapor reacted with atmospheric gas on the substrate surface due to laser heating, when the temperature of the laser-irradiated part was higher than 450°C for AlN and 230°C for ZnO. Not only the substrate temperature, but also the thickness of the Al and Zn layers, which are deposited during the time interval between the first laser irradiation and subsequent laser irradiation, was an important factor for realizing the selective growth. The critical thickness was found to be 0.2 nm and 6 nm for AlN and ZnO, respectively. Two-dimensional selective growth and three-dimensional micro free-form fabrication of AlN were performed under these conditions using a two-dimensional laser scanning setup. The AlN layer was successfully deposited in accordance with a laser drawing pattern, even when the drawing pattern changed during synthesis.
The Effect of Hydrogen Addition on the Fluorine Doping Level of SiOF Films Prepared by Remote Plasma-Enhanced Chemical Vapor Deposition Using SiF4-Based Plasmas
Authors: Pankov Vladimir , Alonso Juan Carlos , Ortiz Armando
Published: October 2002

Fluorinated silicon dioxide films (SiOF) have been prepared by high-density remote plasma-enhanced
chemical vapor deposition from silicon tetrafluoride (SiF4), oxygen and helium feedstock gas
mixture at substrate temperature as low as 175°C. Addition of hydrogen has been found to control the
fluorine doping level of the SiOF films over a wide range of fluorine concentrations while the SiF4-to-O2
flow rate ratio is kept constant. It has been confirmed that hydrogen addition does not lead to the
incorporation of hydrogen in detectable quantities into the grown film with Si–F
x
bond concentrations in
the range of 0.5–4.9 at.% because of effective mutual scavenging behavior of fluorine and hydrogen in
the entire range of hydrogen flow rates used. The decrease in the refractive index of the SiOF films
from 1.463 to 1.410 and the increase in Si–O–Si bonding angles from about 137° to about 148° were
found to be approximately linear with the increase in fluorine concentration. The hydrogen added to the
process gas mixture has been found to play an active role in the film formation process affecting both
the surface reactions and properties of the obtained SiOF films.
Application of Al3Hf/Hf Bilayered Film as a Diffusion Barrier to Al Metallization System of Si Large-Scale Integration
Authors: Satoko Shinkai Satoko Shinkai , Katsutaka Sasaki Katsutaka Sasaki , Yoshio Abe Yoshio Abe
Published: October 2002

We have attempted to improve the reliability of Al metallization system of Si-LSI, using Hf3Si2 silicide with the lowest contact resistivity. Al3Hf/Hf bilayered films were interposed as a diffusion barrier between Al and Si in order to realize both preservation of the Al overlayer and sufficiently low contact resistivity at the Si interface. We have investigated the interfacial solid-phase reaction of the Al/Al3Hf/Hf/Si contact system by means of X-ray diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy analyses, and compared it with that of the Al/Hf/Si system. It is revealed that the Al/Al3Hf/Hf/Si system is satisfactorily stable up to 420°C at which the formation of the Hf3Si2 phase occurs at the Si interface.
Monte Carlo Simulation of 1 eV–35 keV Electron Scattering in Teflon
Authors: Palov Alexandre , Fujii Haruhisa , Hiro Sanju
Published: October 2002

A simple physical model of ≈1 eV–35 keV electron scattering in insulating polymers was
proposed. A new correction to Slater's exchange potential was used for the description of low-energy
elastic electron scattering. The simulation of electron trajectories was performed using the Monte Carlo
technique. The integral and differential characteristics such as the total secondary electron yield and elastic
and backscattering coefficients for Teflon were investigated for ≈1 eV–35 keV electron beams. The charge
distribution inside Teflon as a function of the penetration depth was also calculated. The obtained results
are in a good agreement with available experimental data.
Production of Highly Charged Xe ions from the RIKEN 18 GHz Electron Cyclotron Resonance Ion Source using a Biased Electrode
Authors: Nakagawa Takahide , Biri Sandor , Kidera Masanori , Miyazawa Yoshitoshi , Hemmi Masatake , Chiba Toshiya , Inabe Naohito , Kase Masayuki , Kageyama Tadashi , Kamigaito Osamu , Goto Akira , Yano Yasushige
Published: October 2002

We have observed the enhancement of Xe30,32+ ion beam intensity from
the RIKEN 18 GHz electron cyclotron resonance ion source (ECRIS) using an
electrode at bias voltage of ∼ -100 V. We have successfully obtained beam
intensities of 11 eµA for the Xe30+ ion beam and 4 eµA for the Xe32+ ion
beam using this method at an extraction voltage of 13 kV.