bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Dual Hollow Cathode Arc Chemical Vapor Deposition by Optical Emission Spectroscopy
Authors: Chau-Nan Hong Gou-Tsau Liang
Published: October 2002

Optical emission spectroscopy (OES) using Ar actinometry is employed to characterize plasma in a dual hollow cathode arc chemical vapor deposition system to study the effect of electron bombardment on diamond growth. Using OES, it was found that the H atom concentration (Hα/Ar) and the electron temperature (Hβ/Hα) increase significantly in the substrate current below a threshold, and become insensitive to the substrate current above the threshold. In contrast, the growth rate is almost constant below the threshold and increases significantly with the substrate current above the threshold. It is concluded that increasing the substrate current to below the threshold first shifts the plasma to the substrate, and then, increasing the current above the threshold increases electron bombardment onto the surface only. The greatly enhanced growth rate above the threshold is mainly due to surface activation by electron bombardment. Electron bombardment evidently replaces some functions of H atoms in diamond growth. OES results also show that H concentration is high and electron temperature is low in the growth using CHCl3, compared with that using CH4. The possible reasons for and effects of CHCl3 on the higher growth rate and poorer film quality are discussed.
The Studies on Micro-Structural Defects in Deformed Composite Matrix of Al–Si–Mg and SiC
Authors: Karmakar G. , Sen R. , Meikap A.-K. , Chattopadhyay S.-K. , Chatterjee S.-K. , Surappa M.-K.
Published: October 2002

Detailed Fourier line shape analysis has been performed on three different
compositions of the composite matrix of Al–Si–Mg and SiC. The alloy composition in
wt% is Al–7%Si, 0.35%Mg, 0.14%Fe and traces of copper and titanium (∼0.01%)
with SiC varying from 0 to 30 wt% in three steps i.e., 0, 10 and 30 wt%. The line shift
analysis has been performed by considering 111, 200, 220, 311 and 222 reflections after
estimating their relative shift. Peak asymmetry analysis has been performed considering
neighbouring 111 and 200 reflections and Fourier line shape analysis has been performed after considering the multiple orders 111 and 222, 200 and 400 reflections.
Combining all these three analyses it has been found that the deformation stacking
faults both intrinsic α′ and extrinsic α′′ are absent in this alloy system whereas the
deformation twin β has been found to be positive and increases with the increase of SiC
concentration. So, like other Al-base alloys this ternary alloy also shows high stacking
fault energy, and the addition of SiC introduces deformation twin which increases
with its concentration in the deformed lattices.
New Characterization Technique for Rubbed Polyimide Film for Liquid Crystal Display
Authors: Tanooka Daisuke , Itoh Satoshi , Hirosawa Ichiro
Published: October 2002

A new technique is proposed to characterize optical anisotropy of rubbed polyimide film
used in liquid crystal displays. The technique consists of measuring the polarization of reflected
light in various incident orientations using a combination of a microscope objective, a half-wave
plate, and a two-dimensional position-sensitive detector. High spatial resolution without
mechanical rotation of the sample is achieved. The performance of this technique was
demonstrated by observing a rubbed polyimide film on a glass substrate.
Buried Interfaces in Mo/Si Multilayers Studied by Soft-X-Ray Emission Spectroscopy
Authors: Miyata Noboru , Ishikawa Sadayuki , Yanagihara Mihiro , Watanabe Makoto
Published: October 2002

We measured the Si L23 soft-X-ray emission spectra for Mo/Si multilayers using
monochromatized synchrotron radiation near the Si L23 absorption threshold. On the basis of
the spectral analysis, it was determined that the interfaces of Mo/Si multilayers consist of
Mo3Si interlayers of 0.8±0.1 nm in thickness. This study confirmed that soft-X-ray emission
spectroscopy is a useful method of studying buried layers and
interfaces nondestructively.
Adsorption of Ba on Si(001)2 ×1 Surface
Authors: Jeong-Seon Kim Jeong-Seon Kim , Kyu-Wook Ihm Kyu-Wook Ihm , Chan-Cuk Hwang Chan-Cuk Hwang , Hak-Su Kim Hak-Su Kim , Yong-Ki Kim Yong-Ki Kim , Chilgee Lee Chilgee Lee , Chong-Yun Park Chong-Yun Park
Published: October 2002

The initial adsorption of Ba on the Si(001)2 ×1 surface at 870°C has been studied by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and angle-integrated ultraviolet photoelectron spectroscopy (AIUPS). The valence band, Si and Ba core level spectra and the work-function change (Δφ) were measured. The double domain (DD) (2 ×3)-, DD c(2×6)- and DD (2×1)-Ba surfaces appeared depending on the Ba coverage. AIUPS results show that both DD (2 ×3)-Ba and DD (2 ×1)-Ba surfaces are semiconducting in nature. The intensity ratio data of XPS core levels (Ba 3d/Si 2p) and the work-function change data reveal that the Ba coverages of the (2×3)-Ba and the DD (2×1)-Ba surfaces are 1/3 ML and 1/2 ML, respectively. The AIUPS spectra show that the structural models with Ba coverage of 1/3 ML and 1/2 ML, at the bridge sites between two Si dimers are reasonable for the (2 ×3)-Ba and the (2 ×1)-Ba surfaces, respectively.
Influence of Thermal Annealing on GaN Buffer Layers and the Property of Subsequent GaN Layers Grown by Metalorganic Chemical Vapor Deposition
Authors: Ito Takahiro , Sumiya Masatomo , Takano Yasushi , Ohtsuka Kohji , Fuke Shunro
Published: October 2002

We have investigated the influence of low-temperature buffer
layer deposition conditions, such as thickness and thermal annealing
time, on the properties of the high-temperature GaN growth layer. The
surface morphology of the buffer layer after thermal annealing at
1040°C depends on both the thickness of the buffer layer and
the annealing time. When a thick buffer layer was used, large
trapezoidal growth nuclei were formed after annealing, which led to
the poor crystallinity of the GaN growth layer. On the other hand,
when a thin buffer layer or a fully annealed thick buffer layer was
used, small growth nuclei having a relatively small misorientation
were formed, which led to good crystallinity of GaN growth
layer. Thus, the thermal annealing time must be optimized, taking the
thickness of the buffer layer into the consideration.
Parallel-Processing Diagnostic Program for a Transputer-Based Readout System
Authors: Yuichi Tsujita Yuichi Tsujita , Takeshi Nobori Takeshi Nobori , Chikara Fukunaga Chikara Fukunaga , Manobu Tanaka Manobu Tanaka , Toru Tsuboyama Toru Tsuboyama , Yuzo Asano Yuzo Asano , Shigeki Mori Shigeki Mori
Published: October 2002

A parallel-processing program for system-diagnostic purposes was developed for a transputer-based readout system of a silicon vertex detector (SVD). The data-acquisition (DAQ) system for SVD was constructed as a part of research and development work for the BELLE [name of a detector for an asymmetric collider experiment at High Energy Accelerator Research Organization (KEK)] experiment consisting of data scanners (DS), slave memory modules (SMM) and direct memory access master modules (DMM). The DS, SMM and DMM have a transputer as a core processor. Each transputer was linked by a point-to-point connection with transputer serial interfaces (Inmos-link). The DAQ system was equipped with a transputer network system with the Inmos-links. The diagnostic program has the capability to detect malfunctioning readout components. To minimize the processing time during an experiment, the program runs in parallel on each transputer. For this purpose, the program was written using the programming language, occam. With the benefits of its distributed system architecture and without the need for any operating system, the program is compact with high modularity. In this paper, we report the system architecture of this diagnostic program.
Reduction of Copper Oxide Thin Films with Hydrogen Plasma Generated by a Dielectric-Barrier Glow Discharge
Authors: Sawada Yasushi , Taguchi Noriyuki , Tachibana Kunihide
Published: October 2002

The reduction behavior of sputtered thin Cu2O films with
hydrogen plasma generated by a dielectric-barrier glow discharge was
investigated by means of surface characterization and hydrogen plasma
diagnosis using the vacuum ultraviolet (VUV) line absorption
technique. The reduction model was derived by assuming that the
diffusion of atomic hydrogen in the reduced layer is the
rate-determining step. This reduction model provides a good
approximation of the Cu2O reduction process. The surface hydrogen
concentration estimated from this model is higher by an order of
105–106 than the hydrogen atom concentration in the plasma phase
measured
by means of the plasma diagnosis. It is verified that the number of
hydrogen atoms transported onto the solid surface satisfactorily
agrees with that consumed in the Cu2O layer.
Charge Transfer Cross Sections for Uranium
Authors: Tamura Koji , Adachi Hajime , Ogura Koichi , Ohba Hironori , Shibata Takemasa
Published: October 2002

Symmetric charge transfer cross sections between singly ionized ions and
their parent atoms were measured for uranium in the impact energy range of
100–1200 eV. A primary ion beam was extracted from a laser ion source in
which the atoms were ionized by laser resonant photoionization. The slow ions produced in the charge transfer reaction and the fast primary ions were detected with Faraday cups. The cross sections were determined from the ratio
between the number of ions produced in the charge transfer reaction and that of
the primary ion beam. The cross sections increased with ion impact
energy from (1.3±0.3)×10-14 cm2 at 100 eV to
(2.7±0.3)×10-14 cm2 at 1200 eV. The increase
in the cross sections above 100 eV was well reproduced by theoretical
calculations that took into consideration the electronic configurations of
uranium atoms and ions.
Growth by Molecular Beam Epitaxy of Vanadyl Phthalocyanine on Alkali-Substituted Alkali-Halide Mixed Crystal Substrates
Authors: Gomyou Makoto , Nakao Satoru , Hoshi Hajime , Ishikawa Ken , Takezoe Hideo
Published: October 2002

The epitaxial growth of vanadyl phthalocyanine (VOPc) on
KBr–NaBr mixed-crystal substrates was examined. The experimental
results indicate that the orientation and morphology of the film are
primarily affected by the lattice constants of the substrates, but not
by differences in the substituted components, e.g., alkali or
halogen. The VOPc island crystal domains grew even on large-mismfit
NaBr substrates. Their characteristic shape and the possible growth
process are also discussed.
Multi-Mode Air Damping Analysis of Composite Cantilever Beams
Authors: Bergaud Christian , Nicu Liviu , Martinez Augustin
Published: October 2002

A theoretical and experimental study on multi-mode air damping of SiO2–Au composite cantilever beams is presented. Calculation of the resonant frequencies is effected by taking into account the effect of the coated gold layer. Theoretical values agree well with the experimental results up to the third mode. Quality factors are computed using two different models, the first one is based on the equivalent sphere model and the second one uses hydrodynamic functions. For both models, the theoretical results show a very good agreement with experimental ones for the first two modes.
Characterization of Bimetallic Cantilever for Chemical Sensor Application
Authors: Jung Mi-Young , Kim Dae-Wook , Choi Seong Soo , Kang Chi Jung , Kuk Young
Published: October 2002

A microcantilever stylus offers various possibilities as a high-sensitivity chemical sensor. For high sensitivity, the cantilever stylus should have a very sharp tip, a low force constant, and a high mechanical frequency. In this work, a technique for sensing thermal reaction using a bimetallic Si3N4 microcantilever is investigated. The temperature change and heat loss of the bimetallic cantilever will lead to an angular bending of the bimetallic lever. Its thermal response was qualitatively examined during an endothermic chemical reaction using the optical deflection method. The chemical substance used in this experiment is tetradecanol, CH3(CH2)13OH, with the known phase transition temperature of 313 K.
Finite Angular Resolution Mie-Scattering Measurements of Sonoluminescing Bubbles
Authors: Hayashi Shigeo
Published: October 2002

It is suggested that the use of light detectors subtending a steric angle of 0.1–0.2 sr or so is advantageous for enhancing the signal-to-noise ratio while maintaining the square-root rule that the square root of the intensity is proportional to the bubble radius, provided that the scattering angle is 90° or larger.
Characteristics of Molecular Beam Epitaxy Grown GaAs Simultaneously Doped with Si and Be
Authors: Dai Ichiryu Dai Ichiryu , Eriko Sano Eriko Sano , Yoshiji Horikoshi Yoshiji Horikoshi
Published: October 2002

Simultaneous doping (codoping) of n- and p-type impurities in GaAs is investigated using Si and Be as n- and p-type dopants. In highly Si-doped GaAs layers, the electrical activation ratio of Si-donors is much less than unity because of the formation of compensating centers such as antisite Si (SiAs), Si-clusters and Ga vacancies (VGa). Although no enhancement is observed in the electrical activation, it is found that most of these compensating centers disappear as a result of codoping. The integrated photoluminescence intensity in the codoped GaAs layers is much higher than that in the solely Si-doped samples, indicating that simultaneous Si and Be doping decreases the concentration of nonradiative recombination centers created by high Si doping, without lowering the electron concentration.
Strain Relaxation in Surface Nano-Structures Studied by X-Ray Diffraction Methods
Authors: Baumbach Tilo , Lübbert Daniel , Gailhanou Marc
Published: October 2002

We study the lattice strain relaxation in pseudomorphic surface gratings using high resolution X-ray diffraction (XRD), grazing incidence diffraction and elasticity theory. By means of grazing incidence diffraction we determine the grating shape and detect a depth dependent lattice strain relaxation in the grating. Symmetrical and asymmetrical XRD gives evidence of a non-uniform strain relaxation in the etched structures and the creation of a periodic strain field deep in the substrate. The experimental findings are confirmed by an elasticity model which describes the interaction of the different crystalline media. Comparing the measured diffraction maps with calculated ones, we determine the actual strain distribution in the trapezoidal grating and in the substrate.
Helicon-Wave-Excited Plasma Nitridation of GaAs After Short-Time Plasma Oxidation for Fabrication of Damage-Free GaN/GaAs Interface
Authors: Fumio Kasahara Fumio Kasahara , Keisuke Kanazawa Keisuke Kanazawa , Nariaki Okamoto Nariaki Okamoto , Hideaki Ikoma Hideaki Ikoma
Published: October 2002

Short-time (5–30 min) and long-time (5–7 h) helicon-wave-excited (HWP) N2–Ar plasma treatments of GaAs (100) substrates were performed after short-time inductively coupled (ICP) O2–Ar plasma pretreatments, under two processing conditions in which the plasma sheath widths were small and the largest in our plasma apparatus. The detrimental effects of Ar etching during processing, such as plasma-induced damage, could be reduced if the plasma sheath width was larger. For short-time HWP N2–Ar plasma treatment with the small plasma-sheath width, the effective Schottky barrier height decreased and the reverse leakage current substantially increased with the plasma–exposure time, suggesting the introduction of a high density of the plasma–induced defect centers. On the other hand, the effective barrier height did not change and the reverse leakage current decreased for the GaAs samples treated in HWP N2–Ar plasma with the largest plasma–sheath width. Reasonably good MIS C–V characteristics were obtained for the long-time HWP N2–Ar plasma treatment with the largest sheath width.
Analysis of Electrically Active Carbon in Semi-insulating Gallium Arsenide by Infrared Absorption Spectroscopy
Authors: Alt H. Ch. , Wiedemann B. , Meyer J. D. , Michelmann R. W. , Bethge K.
Published: October 2002

Carbon in semi-insulating gallium arsenide (GaAs) crystals has been investigated by Fourier-transform IR absorption spectroscopy, spark source mass spectrometry, and charged particle activation analysis. Procedures for the quantitative evaluation of the 582-cm-1local mode absorption due to carbon on the arsenic sublattice (CAs) are described. The strength of the mode shows a linear correlation with total carbon content measured by spark source mass spectrometry over the concentration range from 3× 1014to 2×1016cm-3. The new calibration factor for the integrated absorption at 77 K is (7.2±0.4)× 1015cm-1, based on a relative sensitivity coefficient of 3.2±0.1 of the spark source mass spectrometry. Calibration factors for the IR absorption method at room temperature are also given.
Theoretical Study of Recharging Instability in Quantum Well Infrared Photodetectors
Authors: Irina Khmyrova Irina Khmyrova , Maxim Ryzhii Maxim Ryzhii , Victor Ryzhii Victor Ryzhii , Robert Suris Robert Suris , Chihiro Hamaguchi Chihiro Hamaguchi
Published: October 2002

We study the response of the electron system in quantum well infrared photodetectors under illumination by infrared radiation to small electric-field and charge fluctuations using the proposed analytical model. It is shown that uniform electric-field distributions corresponding to quasi-neutral quantum wells can be unstable with regard to the excitation of the recharging waves in a wide range of infrared radiation intensities.
Recovery Treatment of EuBa2Cu3O7-δ Thin Films with Activated Oxygen Plasma
Authors: Wakana Osamu Michikami , Koukichi Atsumi Koukichi Atsumi
Published: October 2002

Using high-quality c-axis-oriented EuBa2Cu3O7-δ (EBCO) thin films with transition temperatures (T
ce) of about 90 K, a deterioration treatment by removal of oxygen atoms and a recovery treatment were performed in a sputtering chamber. The removal of oxygen atoms by heating in a mixture gas of Ar+7.5%O2 at 7 Pa resulted in an expansion of lattice constants (c
0) of about 11.86 Å and semiconductive features. Two recovery methods using pure oxygen and activated oxygen plasma were examined. For the treatment with pure oxygen, signs of recovery in structural and transport properties appeared at annealing temperatures (T
sa) above 300°C at an oxygen pressure (P
O2(a)) of 30 Pa, but the as-grown state was not obtained even at P
O2(a)=2000 Pa. For the activated oxygen plasma treatment, where the deteriorated films were exposed to oxygen plasma and oxygen gas was subsequently introduced into the chamber, an almost complete recovery of superconducting and structural properties was achieved. The appropriate conditions for the recovery were T
sa's of 500–700°C, plasma exposure time (t
p) above 30 min, and oxygen partial pressures (P
O2(pc)) above 200 Pa. Atomic force microscope (AFM) images of EBCO films treated at T
sa's below 550°C showed the same spiral structure as those of as-grown films. The image-deformation and growth of outgrowths became obvious with increasing annealing temperature. The change in the surface morphology revealed the substantial movement of constituent atoms from T
sa's of about 600°C. Because the films exhibit optimum superconducting properties in spite of the rapid cooling, it is considered that the movement of constituent atoms induces trilayered perovskite structures with an excess oxygen atom deficiency at high temperatures.
Molecular Beam Epitaxy and Characterization of Layered In2Se3 Films Grown on Slightly Misoriented (001)GaAs Substrates
Authors: Tomohiko Ohtsuka Tomohiko Ohtsuka , Tamotsu Okamoto Tamotsu Okamoto , Akira Yamada Akira Yamada , Makoto Konagai Makoto Konagai
Published: October 2002

In2Se3 epitaxial films with a layered structure were successfully grown on (001)GaAs substrates by molecular beam epitaxy. X-ray diffraction and electron diffraction studies revealed that the crystallinity of the films was improved by using slightly misoriented (001)GaAs substrates. Furthermore, electrical and optical anisotropies were observed in layered In2Se3 films. It was found that the conductivity of layered In2Se3 epitaxial films along the a-axis was much larger than that along the c-axis, and that the absorption coefficient of layered In2Se3 epitaxial films for light polarized parallel to the a-axis was much higher than that for light polarized parallel to the c-axis.
Red Shift of Faraday Rotation in Thin Films of Completely Bismuth-Substituted Iron Garnet Bi3Fe5O12
Authors: Chern Ming-Yau , Lo Fang-Yuh , Liu Da-Ren , Yang Kuang , Liaw Juin-Sen
Published: October 2002

The magnetooptical Faraday rotations of epitaxial films of Bi
x
Y3-x
Fe5O12 (Bi:YIG) grown on [111]-oriented gadolinium gallium garnet (GGG) substrates by pulsed laser deposition (PLD) were studied with bismuth content x = 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0. The Faraday rotation angles, θF, of the films were measured by the method of rotating analyzer ellipsometry (RAE) with the photon energy varied from 1.5 to 3.5 eV. It was shown that in addition to the increase of the Faraday rotation with increasing x, the peaks of θF shifted toward the red region as x changed from 1.0 to 1.5. The peak positions of θF for the completely Bi-substituted iron garnet, Bi3Fe5O12 (BIG), were found at 2.4 and 2.8 eV with peak values as large as -23 deg/µm and 44 deg/µm, respectively
Radical Formation of Lithium and Magnesium Citrates for Electron Spin Resonance Dosimetry
Authors: Hassan Gamal M. , Uesugi Akihiko , Ikeya Motoji
Published: October 2002

Lithium citrate (Li3C6H5O7: (CH2COOLi)2C(OH)COOLi); Li-citrate) and magnesium citrate (Mg3(C6H5O7)2: Mg2(CH2COO)4Mg(C(OH)COO)Mg; Mg-citrate) were irradiated by γ-rays to study radicals with electron spin resonance (ESR). A doublet spectrum has g=2.0044 ±0.0005 and hyperfine splitting of A/gβ=2.5 ±0.2 mT in Li-citrate. Mg-citrate shows a triplet spectrum with g=2.0032 ±0.0004 and hyperfine splitting of A/gβ=2.21 ±0.18 mT. The energy level, g-factor, A/gβ and optical absorption spectra of several radicals have been calculated using software of MOPAC-V2 and Gaussian-98 based on the unrestricted Hartree-Fock: (UHF). Abstraction of hydrogen from –CH2 is expected for Li-citrate, and homolytic cleavage of the OH group is expected for Mg-citrate. The powders of both Li-citrate and Mg-citrate are six times and five times more sensitive to the γ-ray dose, respectively than a commercial alanine dosimeter. The numbers of free radicals per 100 eV (G-values) were 0.77 ±0.25 and 1.11 ±0.35 for Li-citrate and Mg-citrate, respectively.
Effects of Post-Annealing in H2S on Photo- and Electroluminescence Properties of SrS:Ce Thin Film
Authors: Morishita Takashi , Matsuyama Hiroyoshi , Matsui Masahiro , Wakihara Masataka
Published: October 2002

The luminescence properties of cerium-activated strontium sulfide phosphor
after annealing in H2S atmosphere are investigated. A peculiar excitation band around
355 nm is observed in photoluminescence (PL) excitation spectra, which stems from a
trap state in the band gap. It is found that the intensity of the electroluminescence (EL)
increases with increasing intensity of the peculiar peak at 355 nm. The trap state is
considered to be involved in the EL emission mechanism.
Optical Emission Spectrum Analyses during Pulsed Laser Deflash of Integrated Circuit Packages
Authors: Hong Min-Hui , Lu Yong-Feng , Chen Qiong
Published: October 2002

Optical emission spectrum analysis during Nd:YAG laser deflash of molding compound
for integrated circuits (IC) packaging is investigated. Dependence of spectral line and band
intensities for SiO molecules, Si excited atoms and ions on laser fluence is measured to study
plasma species evolution. Threshold fluences for the spectral line and band appearance are
also estimated. Temporally resolved optical emission spectrum analysis shows that the
spectral lines and bands appear and recombine at different delay times after laser irradiation.
Mechanism for spectral line generation and recombination is found to be attributed to strong
collisions among plasma species.
Thermal Stability of Photostimulated Luminescence Centers in BaFBr and BaFBr:Eu2+ Single Crystals
Authors: Ohnishi Akimasa , Mori Nobufumi , Kan'no Ken-ichi
Published: October 2002

The thermal stabilities and mutual conversion processes of photostimulated
luminescence (PSL) centers in BaFBr and BaFBr:Eu2+ crystals have been studied by
measuring the changes of PSL spectra with a pulse-annealing technique after
exposure to X-rays at 20 K. The O2- PSL band in BaFBr was found to exhibit two
thermal stages, i.e., enhancement during pulse annealing at temperatures around
116 K and decrement after annealing at temperatures above 200 K. On the other
hand, the Eu2+ PSL band in BaFBr:Eu2+ remains constant after the enhancement
during pulse annealing at around 116 K. These facts are well explained by that O-–F(Br-) pair defects and Eu3+ centers are responsible for O2- and Eu2+ PSL processes
at 20 K, respectively. In addition to this, the decrement of the Eu2+ emission yield
after X-ray irradiation at RT indicates that Eu3+ centers converted from Eu2+ ions by
capturing holes are responsible for the PSL process operating at RT in
BaFBr:Eu2+.
Enhanced Dielectric Properties in SrTiO3/BaTiO3 Strained Superlattice Structures Prepared by Atomic-Layer Metalorganic Chemical Vapor Deposition
Authors: Zaiyang Wang Zaiyang Wang , Tomohiko Yasuda Tomohiko Yasuda , Shigeo Hatatani Shigeo Hatatani , Shunri Oda Shunri Oda
Published: October 2002

We describe the investigation of epitaxial SrTiO3/BaTiO3 strained superlattice films prepared by an atomic-layer metalorganic chemical vapor deposition (ALMOCVD) method. Transmission electron microscopy (TEM) observation shows that the multilayered structure is globally uniform and that the interfaces formed between the different layers are of low roughness. X-ray diffraction (XRD) analysis reveals a series of satellite peaks on both sides of the zero-order peak, a characteristic feature of the superlattice structure. Careful analysis of XRD and HRTEM images suggests that the tetragonality in the superlattice films is enhanced; this is presumably due to strain caused by heteroepitaxial growth. Dielectric constants of the superlattice films increase with decreasing period of the superlattice structure. An equivalent oxide thickness of 0.8 nm is obtained. These results demonstrate that the ferroelectricity of SrTiO3/BaTiO3 superlattice films can be controlled artificially by fixing the period of the superlattice.
Ion Collection from Photoionized Plasma with a Wire Electrode in a Weak Magnetic Field
Authors: Adachi Hajime , Tamura Koji , Ogura Koichi , Shibata Takemasa
Published: October 2002

Ions were collected on electrodes from photoionized plasma with
a wire electrode in a weak magnetic field. It was shown that ion
collection time using a wire electrode was hardly affected by magnetic
fields of up to 150 G. This method was effective even in the presence
of a magnetic field.
Refractive Third-order Nonlinearity in Vanadium-oxide Phthalocyanine Micro-crystals
Authors: Rangel-Rojo Raúl , Yamada Shinji , Matsuda Hiro , Kasai Hitoshi , Komai Yuko , Okada Shuji , Oikawa Hidetoshi , Nakanishi Hachiro
Published: October 2002

We report a study on the resonant third-order nonlinear optical
response of vanadyl-phthalocyanine micro-crystals. The refractive and
absorptive contributions to the nonlinear response at several wavelengths
across resonance were determined by employing the z-scan technique with a
tunable picosecond pulsed laser source. The samples studied were cyclohexane
suspensions of vanadium-oxide phthalocyanine micro-crystals 40 nm in
diameter. These
micro-crystals represent an interesting alternative for the production of
solid state samples of good optical quality through relatively simple
techniques. Experimental results show that for wavelengths above 610 nm, the
sample presents saturation of absorption, while for shorter wavelengths,
induced absorption is found. Around 610 nm however, the absorptive
contribution to the nonlinearity vanishes while a finite refractive
contribution remains. This wavelength region is therefore potentially useful
for all-optical switching applications.
Possibility of Submillimeter Slow Surface Wave Resonance in a Two-Layer Parallel-Plate Waveguide Containing n-Type or p-Type InSb Slab
Authors: Yodokawa Shinichi , Kosaka Satoru , Obunai Tetsuo
Published: October 2002

The magnetic field dependence of submillimeter wave propagation in a
two-layer parallel-plate waveguide containing n-type or p-type InSb slab has
been experimentally studied at 526 GHz and 671 GHz. In each case, a
resonant peak appeared on the transmission corresponding to the
theoretically predicted slow surface wave resonance. Particularly with n-InSb,
nonreciprocity of at least 20 dB was experimentally observed for transmission
at the applied magnetic field of 0.2 T.
A Direct Determination Technique for Azimuth Alignment in Photoelastic Modulation Ellipsometry
Authors: Yu-Faye Chao Yu-Faye Chao , Charn-Kuo Wang Charn-Kuo Wang , Shing Liu Shing Liu
Published: October 2002

Instead of the nulling method, a three-intensity-measurement technique is proposed to determine the azimuth deviation of the polarizer (P), photoelastic modulator (PEM) and analyzer (A) with respect to the specimen surface for ellipsometric measurements. After the initial alignment in a straight-through setup, we adjusted the azimuth of P at 45° to the strain axis of the PEM. Arranging a Polarizer-PEM-Sample-Analyzer ellipsometer by subjecting a specimen at the required incident angle, we measured a set of three DC radiances at the zero point of the zero-order Bessel function. In addition to the azimuth deviation, the ellipsometric parameter can also be determined from the same measurements.
Characterization of Etching Damage in Cl2/H2-Reactive-Ion-Etching of GaInAs/InP Heterostructure
Authors: Nunoya Nobuhiro , Madoka Nakamura Madoka Nakamura , Munehisa Tamura Munehisa Tamura , Shigehisa Arai Shigehisa Arai
Published: October 2002

The etching damage induced by electron-cyclotron-resonance reactive-ion-beam-etching (ECR-RIBE) using pure Cl2 gas and Cl2/H2 mixture gas was characterized by photoluminescence (PL) intensity at 77 K of GaInAs/InP heterostructure. By using a GaInAs/InP multiple layer structure consisting of various thicknesses of GaInAs layers, the PL intensity dependence on the depth from the dry etched surface was obtained and the depth profile was characterized by a Gaussian distribution function with parameters of substrate voltage, mixture ratio of etching gas and substrate temperature. As a result, it was indicated that nonradiative recombination traps induced by ECR-RIBE were reduced to one order of magnitude smaller by adopting a negative bias voltage to the sample, Cl2/H2 mixture gas rather than pure Cl2 gas and a lower substrate temperature.
A GaAs Micro Solar Cell with Output Voltage over 20 V
Authors: Ohsawa Jun , Kawasaki Masanori , Tanaka Tatsuhiko , Tsuchida Nuio , Hayakawa Soichiro , Yoshida Mitsuru
Published: October 2002

Twenty-four micro-solar cells connected in series have been fabricated on semi-insulating
(SI) GaAs substrates for application in the fields of micro-electromechanical systems. The array
was formed in an area of 0.8×1.0 mm2, and exhibited an open-circuit voltage of 22.5 V under
illumination of 5 mW at the wavelength of 815 nm. Calculation and experiment has demonstrated
that, unlike conventional solar cells, the shunt resistance deteriorates the output characteristics far
more seriously than the series resistance in the case of micro-solar cells. Leakage currents in both
the unit diode and the substrate were evaluated separately. A quantitative estimate based on the
measurements revealed that photocurrents generated in the surface of the SI substrate could
function as a vital shunt resistance. Light-blocking metal films were successfully employed to
obtain high output voltage.
Characteristic Variation of Exposure Pattern in Cell-Projection Electron-Beam Lithography
Authors: Kotera Masatoshi , Yamaguchi Kiyoshi , Okagawa Takashi , Matsuoka Koji , Kojima Yoshinori , Yamabe Masaki
Published: October 2002

The characteristic variation of an exposure pattern with various optical
parameters is calculated in a typical cell-projection lithography system by
using an electron trajectory simulation. The Coulomb interaction effect
among electrons in the beam is calculated which determines the pattern blur
at the wafer surface. The acceleration voltage is 50 kV, the exposure pattern
is a series of line and space, and the field size is
5 µm×5 µm. As the beam
current density varies from 2 to 13 A/cm2 at the specimen surface, the pattern
blur is evaluated in parameters of (1) the probability of electrons to be in the
designed pattern, (2) the full width at half maximum and (3) the contrast of the
electron density distribution at the wafer surface, as the line width varies
from 0.13 to 0.2 µm.
Studies on Defect Inspectability and Printability Using Programmed-Defect X-Ray Mask
Authors: Watanabe Hiroshi , Kikuchi Yukiko , Marumoto Kenji , Matsui Yasuji , Yabe Hideki , Aya Sunao , Okada Ikuo , Takeuchi Nobuyuki
Published: October 2002

The defect inspectability and printability of X-ray masks have
been studied. To clarify the issues concerning the present
inspection system, we made an X-ray mask programmed with various
defects, such as clear and opaque defects, dimension error and
positional shift, for typical patterns such as line-and-space
(L&S), hole and 2-dimensional patterns. Both the mask pattern and
printed pattern on the wafer were specially inspected using the
electron-beam inspection system SEM-Spec701 for the case of L&S
patterns. In order to estimate the sensitivity required of the
next-generation inspection system, we investigated the critical
dimension (CD) errors due to mask defects, by comparing the printed
patterns of the programmed-defect mask and the dose image profile
calculated with the lithographic simulator Toolset, developed at
Wisconsin University. Based on these results, we discussed the
critical mask defect sizes that result in 10 nm CD error, and found
that defects larger than 40 nm would significantly affect 100 nm
L&S patterns.
Lithographic Performance of a Chemically Amplified Resist Developed for Synchrotron Radiation Lithography in the Sub-100-nm Region
Authors: Deguchi Kimiyoshi , Nakamura Jiro , Kawai Yoshio , Ohno Terukazu , Fukuda Makoto , Oda Masatoshi , Kochiya Hiroyuki , Ushiyama Yukihiko , Hamada Hiroshi , Shimizu Takashi
Published: October 2002

In this article, we evaluate the lithographic performance of a newly developed three-component chemically amplified negative resist in the sub-100-nm region which utilizes
polyhydroxystyrene partially protected by t-Boc groups as a base polymer; alicyclic-bromides with a ketonic group as a highly efficient acid generator;
hexamethoxymethylmelamine as a cross-linker; and basic added compounds. The resist
will extend the feasibility of synchrotron radiation lithography for LSI fabrication down
to the 70 nm line and space patterns with an acceptable sensitivity, a large exposure latitude, and good performance in LSI processes.
Contact Hole Etch Scaling toward 0.1 µm
Authors: Aoi Nobuo , Hayashi Shigenori , Yamanaka Michinari , Kubota Masafumi , Ogura Mototsugu
Published: October 2002

Reactive ion etching (RIE)-lag, i.e., the dependence of contact
etched depth D on contact diameter φ, for deep quarter micron
contact hole etching has been studied down to 0.1 µm
contact. The nonlinearity between φ and D was found to be
successfully converted into a linear relationship with reciprocal
plots of φ and modified contact etched depth (D+h), taking
into account the resist thickness h. In addition, by introducing
the dependence on etching time t as the intercept in the
relationship, the simple experimental equation was proposed in a new
form to describe RIE-lag. This permits the prediction of etching
rates of smaller contacts in the future and will be useful to
investigate the etching mechanism.
Modeling the Impact of Varied Surface Topologies on Irregular Boron Diffusion Profiles
Authors: Rumpf Robert , Suzuki Kenichiro
Published: October 2002

The relationship between the deep-boron diffusion profile and the surface shape of a silicon substrate was
studied. A heavy degree of surface dependence was established. This surface dependence was quantified for a
set of specific process conditions. A simulator that can model the effects of surface variation was created, and
found to be remarkably successful for both two- and three-dimensional
simulations.
Fabrication of Carbon-Based Field Emitters Using Stamp Technology
Authors: Akiyoshi Baba Akiyoshi Baba , Masafumi Hizukuri Masafumi Hizukuri , Masakazu Iwamoto Masakazu Iwamoto , Tanemasa Asano Tanemasa Asano
Published: October 2002

We propose and demonstrate stamp technology, a novel processing technique for a field electron emitter, in which emitter tips are fabricated by pressing a mold into a spin-coated organic material to completely transform the shape of the mold.
The material is then modified by ion irradiation to produce a carbon-based emitter material.
Starting materials tested were a high-temperature-cured polyimide and a photoresist (novolac resin).
The shape of the mold can be completely transferred to these materials at pressure over 700 MPa at 250°C.
A field-emission current up to the order of µA is obtained from emitters fabricated by this new technology with modification using Ar-ion irradiation at an energy of 100 keV to a dose of 3×1016 cm-2.
The ion-beam-irradiation effect on polyimide and photoresist materials is also investigated in terms of electrical conductivity and chemical bonds.
Novel Process for Fabricating Nanodevices Consisting of Carbon Nanotubes
Authors: Hidehiro Nishijima Hidehiro Nishijima , Seiji Akita Seiji Akita , Yoshikazu Nakayama Yoshikazu Nakayama
Published: October 2002

The microprocesses of nanotubes such as attachment, connection, transfer and welding have been demonstrated using a scanning electron microscope. These processes led us to fabricate nanotube devices such as probes used in scanning probe microscopy and diodes with homojunctions or heterojunctions. A tapping-mode atomic force microscope with nanotube probes images the fine structures of biological and industrial specimens. The measurements of electrical properties of the diode devices with homojunctions show no considerable disturbance in the carrier transport and a high current density of ∼107A/cm2without power dissipation in the diodes. A diode with a double barrier heterojunction exhibits a switching property with the onset voltage of ±1.9 V. These properties suggest that the nanotubes used in the diodes are semiconducting.
AlGaAs/GaAs Laser Diodes with GaAs Islands Active Region on a Si Substrate with Higher Characteristic Temperature
Authors: Kazi Zaman Iqbal , Egawa Takashi , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

AlGaAs/GaAs laser diodes with GaAs islands active region on a Si substrate have been fabricated by a conventional metal-organic chemical vapor deposition (MOCVD) method. Lasing via secondary state with lasing wavelengths of 776 and 771 nm under pulse and continuous wave (CW) conditions, respectively, has been observed. Temperature dependence characteristics show both, a higher characteristic temperature and higher internal quantum efficiency for the self-formed island laser than those of a quantum well (QW) laser on Si, for the whole temperature range (50–150 K) measured.
Simple System for Generation and Detection of Tunable-Frequency Far Infrared Light
Authors: Toshihiro Hori Toshihiro Hori , Norihisa Hiromoto Norihisa Hiromoto , Masayuki Izutsu Masayuki Izutsu
Published: October 2002

The system described in this paper has a simple optical configuration for guiding far infrared light to a detector, and thus requires neither a Michelson-type diplexer nor a Fabry-Perot-type filter, both of which require fine adjustments. In this system, all the components that generate, guide, and detect far infrared light work at room temperature. It uses a Schottky barrier diode for heterodyne detection rather than a conventional thermal detector, such as a cooled bolometer for direct detection.
The system is simpler than the conventional system, yet it maintains high sensitivity to FIR radiation.
Experimental results demonstrate the principal behavior of this system. The modulation factor and the tunable-frequency far infrared power is estimated by using an equivalent circuit model with a Schottky barrier diode. The estimated far infrared power is compared with the values reported in other papers. The results of a gas absorption measurement with this system are also discussed.
The Performance of An All-Solid-State Electrochromic Display Consisting of WO3 and TiO2 Films with Polyethylene Oxide Gel Electrolyte
Authors: Zhang Zhang , Xuping Xuping , Su Su , Lianyong Lianyong , Li Li , Qing Qing , Lu Lu , Zuhong Zuhong
Published: October 2002

An all-solid-state electrochromic display employing a sputtered WO3 film as the electrochromic layer and sputtered TiO2 film as the counterelectrode with a
polyethylene oxide (PEO)-based gel electrolyte has been fabricated. The properties of the WO3 film, TiO2 film and PEO gel electrolyte have been investigated. The
conductivity of the PEO gel electrolyte is as high as 2.6 mS/cm at room temperature. The electrochromic display developed by us was found to exhibit excellent electrochromic characteristics.
Improvement of Electric-Field-Assisted Ion Exchange Method for Planar Microlens Array Fabrication
Authors: Takeo Katayama Takeo Katayama , Yuki Munetaka Yuki Munetaka , Kenichi Iga Kenichi Iga
Published: October 2002

We propose a new processing technique to reproducibly fabricate gradient-index planar microlenses. A uniform microlens array consisting of 300 1-mm-diameter microlenses was successfully realized.
Transferability of the Tight-binding Total Energy Parametrization Method for Carbon: Application to Electronic Structural Calculations of Solid C60
Authors: Moriguchi Koji , Shintani Akira
Published: October 2002

We have studied the transferability of the tight-binding total energy parametrization (TBTE) method for carbon, which has been presented by the Naval Research Laboratory group through electronic structural calculations of solid C60. The TBTE method fails in describing the weak van der Waals interactions among C60 clusters. It has, however, excellent transferability for evaluating electronic properties;thus it is expected to be a new tool for studying diverse carbon systems.
Alignment-Controlled Holographic Polymer Dispersed Liquid Crystal for Reflective Display Devices
Authors: Kato Kinya , Hisaki Tomoko , Date Munekazu
Published: October 2002

A new type of holographic polymer dispersed liquid crystal (HPDLC) device in which liquid-crystal (LC) alignment is controlled by polymerized layers has been developed. In the alignment-controlled HPDLC device, the polymerized regions (polymer layers) are formed periodically in homogeneously aligned LC. When an electric field is applied vertically between the substrates, the LC molecules in the residual regions (LC layers) rotate towards the electric field. This causes a difference in refractive index between the polymer layers and LC layers, so selective reflection occurs in accordance with Bragg's law. The selectively reflected light shows strong polarization dependence. Only light polarized parallel to the alignment direction of LC molecules is reflected.
Some Peculiarities of Angular Selective Reflection of Cholesteric Liquid Crystals in an Electric Field
Authors: Kolomzarov Yu. , Kozachenko A. , Lev B. , Nazarenko V. , Sorokin V.
Published: October 2002

We report the peculiarity of selective reflection from a planar cholesteric
liquid crystal layer under the action of a small electric field. Application
of a small electric field leads to a reversible transition from monodomain
to multidomain textures that have a different angular distribution of
reflected light. The mechanism of such transition is discussed.
The Mechanism of Sound Transmission Control in Terms of Structural and Radiation Modes
Authors: Sung Chia-Chi , Huang Chih-Yung
Published: October 2002

The dynamic response of a clamped rectangular plate subjected to plane wave incidence and piezomoment actuation has been derived in our previous research. The result benefits the comparison of acoustic power transmitted through the plate with and without control. The acoustic power is represented in terms of the amplitudes of the structure modal velocities and the velocities of an array of elemental radiators on the plate surface. It was found that the transmitted acoustic power due to the vibration of one structural mode or element depends on the vibration of other structural modes or elements; however, the radiation modes contribute to the transmitted acoustic power independent of other radiation modes. Three control strategies, viz. volume velocity cancellation, minimization of the transmitted sound power, and minimization of the vibration energy of the plate, are employed. The control mechanism in terms of structural and radiation modes is thoroughly discussed. The control is found to be much more effective when it is applied to the high-radiation-efficiency modes than to other modes.
Humidity and Temperature Sensing Using an Optical Fiber and a Corner Cube Prism
Authors: Marenori Kawamura Marenori Kawamura , Takami Takeuchi Takami Takeuchi , Hairul Fuad Hairul Fuad , Susumu Sato Susumu Sato
Published: October 2002

An optical sensing method for the measurement of humidity and temperature, which uses a sensor head composed of a cholesteric liquid crystal (LC) cell and a corner cube prism coated with a cobalt chloride (CoCl2) film is proposed. The CoCl2 film is used as a color reaction reagent for measuring the humidity. The temperature is measured by the shift of the selective reflection band of the cholesteric LC cell. In addition, an OTDR method is applied to measure the humidity and temperature, and the location of the sensor head is also determined.
Intracavity Frequency Doubling in a Femtosecond Ti:sapphire Laser Using Lithium Triborate and Beta-Barium Borate
Authors: Il Kang Young , Ho Cha Yong , Hee Nam Chang
Published: October 2002

The intracavity frequency-doubling characteristics of LiB3O5 (LBO) and
β-BaB2 O4 (BBO) in a femtosecond Ti:sapphire laser were investigated
to generate efficiently blue wavelength, femtosecond pulses.
At a repetition rate of 80 MHz, 24 fs pulses with a spectral bandwidth of 13.7 nm around 422 nm for LBO,
and 29 fs pulses with a spectral bandwidth of 10.4 nm for BBO, were produced.
The minimum pump power to start the mode locking of Ti:sapphire laser with the doubling crystal was about 2.5 W.
With a laser pump power of 5 W, the blue output power of 86 mW with an internal conversion efficiency
of about 3.3% from LBO and that of 114 mW with 4.5% from BBO were obtained.
Structure and Piezoelectric Properties of 0.9 Pb(Zr,Ti)O3–0.1 Pb(Mg,Nb)O3 Films Prepared by Metalorganic Deposition Process
Authors: Sumi Kouji , Qiu Hong , Shimada Masato , Sakai Shinri , Nishiwaki Tsutomu
Published: October 2002

The 800-nm-thick 0.9 Pb(Zr,Ti)O3–0.1 Pb(Mg,Nb)O3
(PZT–PMN) were prepared by metalorganic deposition
(MOD) process on Ti/Pt/Ti bottom electrodes. The
structure of the films was investigated by scanning
electron microscopy and X-ray diffraction. The
piezoelectric properties of the films were characterized
by measuring the electrically induced strain using the
cantilever method to determine the piezoelectric charge
constant (d
31) and by measuring the mechanically
induced voltage. The films retain the tetragonal
perovskite structure with both [100] and [111] preferred
orientations and are made up of columnar grains whose
size ranges from 100 nm to 200 nm. The plot of strain
versus electrical field shows a hysteresis loop, which
reveals that the strain depends on the polarity of the top
electrode. The unpoled film is virginally polarized
toward the bottom electrode. As a result, d
31 at an
electrical field of 170 kV/cm is 190 pC/N for positive
polarity and 166 pC/N for negative polarity.