bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Approach for Form Polycrystalline Silicon by Excimer Laser Irradiation with a Wide Range of Energies
Authors: Hara Akito , Kitahara Kuninori , Nakajima Kazuo , Okabe Masahiro
Published: October 2002

We develop a new crystallization method, the “double layer method”. This
method has two steps involving the preparation of polycrystalline silicon film,
each of which consists of a deposition of amorphous silicon followed by exciter
laser irradiation while the substrate is heated. The mechanism for the formation
of polycrystalline silicon by the double layer method is based on the concept that
the remaining crystalline silicon formed by the incomplete melting of the first
polycrystalline silicon layer during the second laser irradiation step acts as a
seed for the growth of polycrystalline silicon. This mechanism provides stable
crystal growth and makes it possible to form high quality polycrystalline silicon
over a wide range of laser energies. Using this new crystal growth method, a
field-effect mobility of 300 cm2/Vs was achieved for n-channel thin-film
transistors.
A Hierarchical Study of Even-Denominator Filling Fractions in Quantum Hall Structure
Authors: Yi Sam Nyung , Ahn Hyung Soo , Yi Kyung-Soo , Lee Jai Hoon , Choi Sang Don
Published: October 2002

A theoretical framework is presented which provides a unified description of the even-denominator fractional quantum Hall structure. We considered states having a pair of additional gauge fluxes attached to the fundamental even filling factor state. The even-denominator hierarchy trees constructed by our approach satisfy a direct sum rule which is also satisfied by Haldane's 1/3, 1/5 trees. The present model should be tested through further experiments and its accuracy lies in the agreement of its results with experimental results.
Homogeneous Growth of Zinc Oxide Whiskers
Authors: Saitoh Hidetoshi , Satoh Minoru , Tanaka Norio , Ueda Yoshikazu , Ohshio Shigeo
Published: October 2002

Several common modes of crystal growth provide particularly simple and elegant examples of
spontaneous pattern formation not only in nature but also under artificial circumstances. We have
already reported that well-organized ZnO whiskers are epitaxially grown using a chemical vapor
deposition technique [Satoh et al..: Jpn. J. of Appl. Phys. 38 (1999) L586]. One aim of this study is to
determine the optimum growth conditions for obtaining the structure containing homogeneous whiskers
grown with a relatively high growth rate. A substrate temperature of 550°C and a vaporizing
temperature of 125°C are the most appropriate for obtaining homogeneous whiskers. Whiskers are
highly oriented in the a-and c-axes directions of the hexagonal structure. The growth rate reached a
maximum value as high as 7.5 nm/s.
Growth Modes of Nd Deposited on Mo(110) Surface
Authors: Jo Sadaharu , Gotoh Yoshihiko
Published: October 2002

We have studied the growth modes of Nd deposited on a Mo(110) surface
by means of reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). Nd grows on the Mo(110) surface in the Stranski-Krastanov growth mode in the temperature range between 500°C and 750°C,
in which a monolayer with a c(5×3) structure grows initially, followed by the
growth of Nd islands. On the other hand, Nd grows on the Mo(110) surface in
the pseudo Frank-van der Merwe growth mode in the temperature range
between room temperature and 500°C. The results of RHEED specular beam
intensity oscillations also support the above-mentioned growth modes.
The Beam Based Alignment Technique for the Measurements of Beam Position Monitors Offsets and Beam Offsets from Quadrupoles in the Pohang Light Source
Authors: Kim K. H. , Huang J. Y. , Ko I. S.
Published: October 2002

The beam based alignment (BBA) technique is applied to the 2-GeV storage ring of the Pohang Light Source to measure the offsets of beam position monitors. This measurement is particularly necessary for beam position monitors (BPMs) plugged into a long (∼10 m) aluminum chamber, since the mechanical deformation of the vacuum chamber is experienced after repeated heating for the outgassing process, and the BPM positions are changed accordingly. A part of the excitation current of each quadrupole magnet is shunted through an electronic shunt circuit. Then, the closed orbit receives a perturbation due to the current reduction. Using two quadrupole magnets, we can measure the offset of each BPM. Also, the BBA technique is applied to measure the beam offsets from the center of quadrupole magnets, and gives information to the survey team about which quadrupole magnets should be aligned mostly. In this process, we introduce the merit function to reduce various errors such as BPM characteristic changes and the lattice imperfection. By minimizing the merit function, we can get the beam offset as the maximized expectation value. This paper presents the BBA technique used and experimental results taken from the 2-GeV Pohang Light Source (PLS) storage ring. When the BPM offset is measured, it is observed that a 3% of the shunt current is suitable.
Simulation of Clustering and Pile-Up during Post-Implantation Annealing of Phosphorus in Silicon
Authors: Erwin Schroer Erwin Schroer , Masashi Uematsu Masashi Uematsu
Published: October 2002

We report on the simulation of the annealing behavior of medium dose
(1013–1014 cm-2)
implanted phosphorus in silicon. It is shown that the transient
clustering of
phosphorus has to be taken into account in order to achieve consistent
simulation
results. The pile-up of phosphorus at the silicon-silicondioxide
interface is
considered by including a diffusion-segregation term in the
diffusion-reaction
equations. We show how the phosphorus clustering impacts the phosphorus
amount
in the pile-up layer and compare the simulation results with available
experimental
data.
Effects of Resist Thickness and Substrate Reflectance on Critical Dimension Bias of Isolated-Dense Pattern
Authors: Kim Hyeong Soo , Kim Hyoung Gi , Kim Myoung Soo , Baik Ki Ho
Published: October 2002

The critical dimension (CD) uniformity of an isolated-dense pattern has been the most critical issue in optical lithography below the wavelength of the illumination source and
much effort has been exerted to improve it. The CD difference between isolated and dense patterns (ID bias), which is caused by proximity effects, is known to be one of the
key factors leading to the deterioration of CD uniformity. Because ID bias is such a complicated phenomenon and affected by many factors, it would be very difficult to control it even though we understand all the factors that lead to it. Much research on ID bias has been conducted; however, the effect of resist thickness on ID bias has not yet been
clearly studied. From our investigations, we have investigated the effects of resist thickness on ID bias and found that ID bias is strongly affected by resist thickness. ID bias changes periodically with resist thickness and the minimum ID bias is obtained by controlling the resist thickness for a specified pattern. We also found that the antireflective coating (ARC) process is an effective method for controlling ID bias.
Effect of Interfacial Carbide Layer on the Raman Spectra in Chemical-Vapor Deposited Diamond Films
Authors: Kim Jung Geun , Yu Jin , ChulLee Jae
Published: October 2002

Diamond films were deposited on the p-Si (100) substrates by hot filament chemical vapor
deposition (HFCVD). Then, the Raman spectra of the diamond films with the substrate removed and
with a carbon layer deposited on the back of the film were compared. We also investigated the
characteristics of the spectra along the direction of the film thickness. The results showed that the
Raman spectra were affected not only by the properties of the diamond films but also by the
interfacial silicon carbide layer, due to the high optical transmittance of diamond. The residual
stresses in the film showed a nonuniform distribution along the film thickness. However, the residual
stress on the top surface of the film almost reflected the average
value for the total film thickness.
Optimization of Panel Parameters and Drive Signals for High-Speed Matrix Addressing of a Bistable Twisted-Nematic Liquid Crystal Display
Authors: Lee Gi-Dong , Park Ku Hyun , Jang Ki Chul , Yoon Tae-Hoon , Kim Jae Chang , Lee Eung-Sang
Published: October 2002

In this paper, we introduce a method to optimize panel parameters and drive signals in a matrix-addressed bistable twisted-nematic (BTN) liquid crystal display (LCD) panel. We measure the effect of data pulses on optical switching characteristics in a BTN LC cell to model the effect theoretically. We introduce a weighting function to model the effect of data pulses on the switching energy as a function of time. Once the weighting function is known, we can estimate the maximum number of lines for a multiplexing operation at a given frame rate by calculating the minimum data pulse width. By characterizing a unit cell while varying panel parameters (for example, d/p ratio), we can optimize parameters for high-speed operation. We found that our theoretical predictions agree very well with experimental results.
Surface Micromorphology of Different Crystallographic Faces of L-arginine Hydrochloride Monohydrate Etched in Organic Solvents
Authors: Mukerji Sudeshna , Kar Tanusree
Published: October 2002

The surface micromorphology of {100}, {010}, {001} and {110} faces of L-arginine
hydrochloride monohydrate (LAHCl) crystals etched in various organic solvents and their
mixtures with water has been studied by optical microscopy. Selective behaviour of the
etchants for revealing screw and edge dislocations, etch channels, etch grooves and
terraced etch pits has been demonstrated. It is observed that addition of impurity like
FeCl3, to the etchants facilitates the formation of dislocation etch pits and is interpreted in
terms of Cabrera's thermodynamic theory of dislocation etch pit formation. Crystallinity of
the as grown crystals is determined from etch pits count in unit area of different faces and
the average dislocation density is found to be ∼104 cm-2.
Development of Surface Morphology of Epitaxial Al2O3 on Silicon by Controlling Reaction between Oxygen and Silicon Surface
Authors: Takayuki Kimura Takayuki Kimura , Makoto Ishida Makoto Ishida
Published: October 2002

Epitaxial growth of Al2O3 on Si has been investigated using ultrahigh-vacuum chemical vapor deposition (UHV-CVD). The uniformity of Al2O3 growth in a wafer was improved by UHV-CVD with a hot-wall heating system, but the surface morphology of grown films was degraded compared with that of films grown by low-pressure chemical vapor deposition (LP-CVD) with a cold-wall heating system. Using oxygen for Al2O3 growth instead of N2O, crystalline quality and electrical properties of Al2O3 films were improved, but microroughness still exist at the Al2O3 surface. A new Al2O3 growth method is proposed taking into account thermochemical considerations. The growth temperature of Al2O3 was lowered at a temperature below 780°C to improve the surface morphology. Although the surface morphology of Al2O3 film was improved, its crystalline structure was degraded by the low-temperature growth. Then, a high-temperature growth was performed on the Al2O3 layer grown at the low temperature, to recover the crystalline structure of the grown films. Using two complementary growth steps with different temperatures, the surface morphology and electrical properties of epitaxial Al2O3 films on Si substrates were improved.
Anomalous Time-of-Flight Signals from Polarization-Gradient-Cooled Atoms
Authors: Fukuda Kyoya , Hasegawa Atsushi , Kajita Masatoshi , Morikawa Takao
Published: October 2002

The time-of-flight signal from polarization-gradient-cooled Cs atoms indicates
that the cooling effect first decreases with increased detuning, but is restored as the
detuning is increased beyond -170 MHz. It also indicates that this detuning also causes
a shift in the signal peak. These penomena can be explained by taking into account the
influence of the neighboring transition.
A Pressure-Induced Phase Transition in a Ternary Microemulsion with an Assembly of a New High-Pressure Cell and Small-Angle X-Ray Scattering Apparatus
Authors: Seto Hideki , Okuhara Daisuke , Nagao Michihiro , Komura Shigehiro , Takeda Takayoshi
Published: October 2002

A small-angle X-ray scattering (SAXS) apparatus for use at high pressure was developed in
order to investigate pressure-induced phase transition in a ternary microemulsion consisting of dioctyl
sulfosuccinate sodium salt (AOT), water and n-decane. A high-pressure cell was designed to study
structural phase transitions in complex fluids, and a SAXS software was developed to measure
dynamical structural change of the sub-second order or a successive structural change with
temperature variation. The observed SAXS profiles were explained by combining two models for
small-angle neutron scattering (SANS), and the results obtained from SANS were reproduced. A
pressure jump experiment from the high-pressure lamellar phase to the low-pressure phase was also
carried out.
Measurements of Carrier Mobility and Quantum Yield of Carrier Generation in Discotic Liquid Crystal Hexahexyl-Oxytriphenylene by Time-of-Flight Method
Authors: F. Schmidt Hiroaki Nakayama , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Carrier transport and generation processes in 2,3,6,7,10,11-hexahexyloxy-triphenylene (HHOTP)
have been studied by a time-of-flight
method in various phases. The carrier mobility is estimated by the
curve fitting method in which the spatial distribution of the generated
charge carrier density is taken into consideration. From the
experimentally determined slope-to-intercept value in a field dependence
of generated charge, the zero field quantum efficiency of carrier generation
is estimated to be approximately 0.05% taking the Onsager model into
consideration.
Field Aided Lateral Crystallization of Amorphous Silicon Thin Film
Authors: Park Sang-Hyun , Jun Seung-Ik , Song Kyung-Sub , Kim Chang-Kyung , Choi Duck-Kyun
Published: October 2002

We propose a noble crystallization method of amorphous silicon thin film in this study. Directional
crystallization of amorphous silicon thin film was successfully achieved by applying a DC field
during heat treatment. The crystallization temperature was lowered to 500°C by employing a trace
amount of Ni. The lateral crystallization velocity was 21 µm/h when 53.5 V/cm electric field was
applied at 500°C. It also showed the dependence on the applied field intensity. The directionality of
the resulting crystallization depended on the polarity of the electric field. This noble technology
can be applied to the fabrication of low temperature poly-Si thin film transistors on glass substrates.
Computer Simulation for Analysis of Lattice Polarity of Wurtzite GaN{0001} Film by Coaxial Impact Collision Ion Scattering Spectroscopy
Authors: Sonoda Saki , Shimizu Saburo , Suzuki Yasumasa , Balakrishnan Krishnan , Shirakashi Jun-ichi , Okumura Hajime , Nishihara Takaharu , Shinohara Makoto
Published: October 2002

Signal intensities of coaxial impact collision ion scattering spectra have been
computed for c-axis-oriented GaN films at various incident angles in order to analyse the
lattice polarity based on the three-dimensional two-atom triple-scattering model. It was
found that Ga and N signal intensities show specific incident angle dependences on
(0001) and (0001̄) surfaces. The physical image of each characteristic feature in the
spectra was also clarified.
Gas-Source Migration-Enhanced Epitaxial Growth of AlAs/AlP Superlattices
Authors: Nagano Masahiro , Oishi Yuji , Ohnuma Toshiharu
Published: October 2002

Gas-source migration-enhanced epitaxial growth of AlAs/AlP
short-period superlattices on (001) GaAs substrates at low growth temperature was studied by X-ray
diffraction. The intensities of the peaks, which are related to the superlattices in X-ray
diffraction patterns, increased with decreasing growth temperatures. The intensities of
the peaks were influenced by the group V supply. According to the X-ray diffraction
patterns of (AlAs)
n
/(AlP)
n
(n=1, 2) short-period superlattices grown at 400°C, the average
heterointerface roughness of the (AlAs)1/(AlP)1 superlattice is estimated to be 0.17 Å
and our growth technique shows good potential for obtaining As- and P-containing
compounds.
Micro-Scale Characterization of Crystalline Phase and Stress in Laser-Crystallized Poly-Si Thin Films by Raman Spectroscopy
Authors: Kitahara Kuninori , Moritani Akihiro , Hara Akito , Okabe Masahiro
Published: October 2002

Laser crystallized poly-Si thin films were characterized using micro-Raman spectroscopy.
Mapping measurements of the Si optical-phonon line were carried out for large size grains
generated by the super-lateral growth, where the mapping interval was as small as 0.2 µm. It
was found that the spectral intensity is extremely large at ridges located at grain boundaries. The
map of peak-frequency shift indicated that the tensile stress tends to accumulate in grains and
relax at grain boundaries. The map of spectral width revealed the abrupt variation of the
crystalline phase from large-size grains to microcrystals.
Effect of Higher Silanes in Silane Plasmas on Properties of Hydrogenated Amorphous Silicon Films
Authors: Suzuki Atsushi
Published: October 2002

The properties of hydrogenated amorphous silicon (a-Si:H) were investigated and correlated to the densities of neutral higher silane (HS) molecules in silane radio frequency (rf) glow discharge plasmas which are used to grow a-Si:H films. The suppression of defect densities at the light soaked state was observed for “device-grade” a-Si:H with a decrease in the density of HS. On the basis of the dependence of the density of HS on the deposition rate, it is suggested that deterioration of the properties of a-Si:H deposited at a high deposition rate is attributed to the increase in the number of HSs in silane plasmas.
Sample Preparation and Photoluminescence of ZnO Particles Embedded in Thin Alkali Halide Crystals
Authors: Harada Yoshiyuki , Kondo Hisao , Ichimura Nobuko , Hashimoto Satoshi
Published: October 2002

We have prepared samples of ZnO particles embedded in thin alkali halide crystals by a
melt growth method and have measured photoluminescence spectra at various temperatures. In
the spectra measured at 8.5 K, free exciton (FE) and bound exciton (BE) emission lines are
clearly recognized, while the well-known green band is hardly observed. The FE line appears
at temperatures between 8.5 K and 300 K. The widths of both lines are very sharp and almost
equal to that of ZnO epitaxial layers grown by a molecular beam epitaxy method. These results
strongly suggest that high-quality ZnO particles can be well embedded in thin alkali halide crystals.
Superlattice in YBa2Cu3Ox Single Crystal Induced by Absorption of Water Vapor
Authors: Edo Shoichi , Takama Toshihiko
Published: October 2002

Structural changes in a single crystal of YBa2Cu3O6.4
caused by absorption of water vapor have been investigated by
the X-ray diffraction method. The diffraction measurements
showed that a superlattice twice the original c-axis is formed
after the absorption. One half of the cell length is 13.69 Å,
which is larger by 16.3% than the original length of the c-axis. The lattice constants a and b showed a slight change and
were close to each other in value. On the other hand, the breadth
of the (00l) reflections increased more than twofold that before
the absorption, although the (h00) and the (0k0) reflections
remained sharp. It is thought that the absorption induces
anisotropic strain.
Initial Oxygen Interaction between Ge(100) and Ge/Si(100) Surfaces Compared by Scanning Tunneling Microscopy
Authors: Tsuneo Fukuda Tsuneo Fukuda
Published: October 2002

The initial stage of oxygen interaction on epitaxially grown Ge overlayers formed
on Si(100) (Ge/Si(100)) surfaces and on the Ge(100) surface was compared by scanning
tunneling microscopy in an ultrahigh vacuum. Although both surfaces were terminated
with Ge dimers, suppression of the reaction by molecular oxygen on the Ge/Si(100)
surface was demonstrated at an atomic resolution. In addition, two new types of
oxygen-induced reaction products were identified on the Ge/Si(100) surface.
Enhancement of Negative-Ion-Assisted Silicon Oxidation by Radio-Frequency Bias
Authors: Fujii Takashi , Aoyagi Hitoshi , Kusaba Kouta , Horiike Yasuhiro , Shindo Haruo
Published: October 2002

For low-damage silicon oxidation at low temperature, negative-ion-assisted
oxidation was studied by employing negative ions in oxygen plasma. In the
downstream region of microwave oxygen plasma, the silicon oxidation was
examined under various radio frequencies of the substrate bias. The oxidation depth
showed a strong frequency dependence and had a maximum around the ion plasma frequency and thus, it was concluded that the oxidation was due to the negative ions. An X-ray photoelectron spectroscopy analysis revealed less suboxide in the
negative-ion irradiation compared with the positive-ion oxidation.
Electroluminescence Properties of Three-Layered Organic Light-Emitting Diodes with a Layer of Tetraphenylchlorin or Tetraphenylporphine
Authors: Sakakibara Youichi , Okutsu Satoshi , Enokida Toshio , Tani Toshiro
Published: October 2002

We constructed two organic electroluminescence (EL) devices that
had a light-emitting layer of tetraphenylchlorin (TPC) or
tetraphenylporphine (TPP), which was inserted between a hole
transport layer of
N,N
′-diphenyl-N,N
′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine (TPD) and an electron transport layer of tris(8-hydroxyquinoline) aluminum (Alq3). The TPC device emitted a far-red EL band at around 750 nm, which we ascribed to emission from aggregated TPC sites. The TPP device emitted a red EL band at 660 nm and a far-red EL band at 720 nm, which we ascribed to emission from monomer-like TPP sites. Both devices also emitted green EL bands due to Alq3 emission although the emission was partly filtered off by absorption of the TPC or TPP layer.
Ultrasound-Assisted Optical Reflectometry in Highly Scattering Media
Authors: Hisaka Masaki , Sugiura Tadao , Kawata Satoshi
Published: October 2002

We have developed an optical reflectometry system to investigate the inside of a
scattering medium by using focused ultrasound wave to specify the measuring
point. The reflected light is generated by the variation of the refractive indices
induced by a focused ultrasound wave. The optical reflectometry technique
enables us to observe an internal structure such as a human tissue noninvasively
for biomedical applications. We have observed samples which consist of an
agarose block with a cubic piece of agarose stained with a dye as an absorptive
material. The intensity of the light reflected from the focal region of the
ultrasound is decreased when the measuring point was in the stained agarose
section because of absorption by the dye. Furthermore, we have observed a
sample with a weak scattering object made of agarose surrounded by strong
scattering agarose that contains poly(methyl methacrylate) (PMMA) particles.
Soft X-Ray Dark-Field Imaging Microscope with Wolter-Type Grazing-Incidence Mirrors
Authors: Takano Hidekazu , Yokota Kazuhiro , Aoki Sadao
Published: October 2002

A soft X-ray dark-field imaging microscope with Wolter-type mirrors was
constructed on a laboratory scale. An annular aperture stop was used to cut off the
direct beam, which satisfied the dark-field condition. The image is formed only with
scattered X-rays from the object. It provides not only absorption but also phase shift
information with high contrast. In the dark field, fine particles and defects of the
sample that had not been seen in the bright-field image, could be observed. The
image formation was analyzed by computer simulation. The dark-field images of
organic specimens were also observed and compared with the bright-field images.
Infrared Lattice Absorption in Wurtzite GaN
Authors: Takashi Azuhata Takashi Azuhata , Kazuhiro Shimada Kazuhiro Shimada , Takahiro Deguchi Takahiro Deguchi , Takayuki Sota Takayuki Sota , Katsuo Suzuki Katsuo Suzuki , Shigefusa Chichibu Shigefusa Chichibu , Shuji Nakamura Shuji Nakamura
Published: October 2002

Two-phonon absorption spectrum of wurtzite GaN was measured for
the first time and was compared with two-phonon density-of-states of
zincblende GaN obtained by lattice-dynamical calculations with an adiabatic
bond-charge model. All structures in the spectrum were well explained by
phonon structures of zincblende GaN. As a method to analyze two-phonon
absorption spectra of wurtzite materials, proposed was the utilization of
phonon dispersion curves of corresponding zincblende modifications, and the
method was found to be useful.
Three-Dimensional Microstructures Created by Laser Microfabrication Technology
Authors: Horiyama Makoto , Sun Hong-Bo , Miwa Masafumi , Matsuo Shigeki , Misawa Hiroaki
Published: October 2002

Three-dimensional microstructures with aspect ratios larger than 20 and a solidified wall with a thickness down to 2.0 µm have
been fabricated by the one-photon absorption photopolymerization technique. Lateral and longitudinal spatial resolutions in a single-line
scanning process of as high as 1.0 µm and 0.3 µm, respectively, are reproducible. An experimental system consisting of a common
picosecond pulsed laser and an optical microscope makes laser microfabrication easy to realize, implying a broad application potential.
The Effects of Shallow Germanium Halo Doping on N-Channel Metal Oxide Semiconductor Field Effect Transistors
Authors: Wang Meng-Fan , Chien Chao-Hsin , Chao Tien-Sheng , Lin Horng-Chih , Jong Fuh-Cheng , Huang Tiao-Yuan , Chang Chun-Yen
Published: October 2002

In this paper, we report the use of shallow germanium halo doping on improving the
short-channel effects of deep submicron n-channel metal-oxide-semiconductor field
effect transistors. It is demonstrated that by adding a shallow (i.e., 10 keV)
germanium large-angle-tilt implant (LATID), V
th lowering in short-channel transistors
is significantly improved. The improvement is found to increase with increasing
germanium dose. A low germanium dose (e.g., 5×1012 cm-2) is also found to
effectively improve the drain-induced barrier lowering (DIBL) of the short-channel
transistors. Our results also show that junction leakage degradation, which has been
previously reported to accompany germanium implants using higher energy, can be
minimized by the shallow low-dose implant used in this study.
Non-Mechanical Angular Multiplexed Holographic Memory System Using Moving Window on Liquid Crystal Display
Authors: Kim Soo-Gil , Kim Kyu-Tae , Kim Eun-Soo
Published: October 2002

By controlling the pixels of a liquid crystal display (LCD) electronically, we
fabricated a real-time moving window on a LCD, through which light passes.
Using the moving window, we suggested a new non-mechanical angular multiplexed holographic memory system and demonstrated the feasibility of the proposed method through optical experiments.
Characterization of Lead-Zirconate-Titanate (PZT) Films Formed by Photo-Decomposition of Metal Organic Polymer
Authors: Zhang Jun-Ying , Boyd Ian W.
Published: October 2002

The characteristics of lead-zirconate-titanate (PZT) films formed by photo-assisted decomposition of
metal organic sol-gel polymer at low temperatures using a 172 nm excimer
lamp is reported. The thickness of the films formed on Si was determined
using ellipsometry while their composition was determined by electron probe
X-ray microanalysis. Current-voltage measurements showed that the leakage
current densities in the PZT films were over an order of magnitude less
than those obtained in films prepared by conventional thermal processing.
Characterization of Nonuniformity of 6H-SiC Wafers by Photoluminescence Mapping at Room Temperature
Authors: Tajima Michio , Nakane Taketomo , Nakata Toshitake , Watanabe Masanori
Published: October 2002

Nonuniformity has been demonstrated of commercially available p-type 6H SiC bulk and epitaxial wafers by using photoluminescence (PL) mapping at room temperature. Three deep-level PL bands with peaks at 1.95, 1.35 and 1.05 eV have been detected for the first time besides the near band-edge emission associated with Al acceptors. The intensity variations of these bands on wafers differ depending on the sample. A circular pattern appeared corresponding to the dark core region of the wafer. A one-sided intensity pattern was observed in an epitaxial layer, which is speculated to reflect inhomogeneous gas flow and/or temperature gradient in the reactor. We believe that the ability of the present technique for the characterization of nonuniformity contributes greatly to the improvement of the crystalline quality of SiC.
Relationship between Critical Current Fluctuation of Superconducting Bicrystal Junction and Junction Parameters
Authors: Enpuku Keiji , Minotani Tadashi , Shiraishi Fumio , Kandori Atushi
Published: October 2002

Critical current fluctuation of bicrystal junctions is estimated from the 1/f flux
noise of the superconducting quantum interference device (SQUID) at T=77 K. The
relationships between the current fluctuation and junction parameters, such as critical
current I
o and resistance R, are obtained. The obtained parameter dependence can be
well explained by using the parameter dependence of the resistance fluctuation reported
by Marx and Gross [Appl. Phys. Lett. 70, 120 (1997)] and the relationship between I
o
and R obtained for the present junctions. The agreement indicates that the critical
current fluctuation is correlated with the resistance fluctuation through the relationship
between I
o and R.
Growth of ZnO on Sapphire (0001) by the Vapor Phase Epitaxy Using a Chloride Source
Authors: Takahashi Naoyuki , Kaiya Kazuhiko , Nakamura Takato , Momose Yoshimi , Yamamoto Hajime
Published: October 2002

Zinc oxide (ZnO) films were deposited on sapphire (0001)
substrates by vapor phase epitaxy using ZnCl2 as a chloride
source. The X-ray diffractogram showed a typical pattern of
epitaxially grown ZnO with a hexagonal structure, and a full
width at half-maximum (FWHM) of 23.3 min was obtained
in the X-ray diffraction profile. Growth rate of the ZnO film
increased with increasing growth temperature, the growth rate
varied from 0.5 to 3.0 µm/h. A strong band edge emission at
370.0 nm was observed at 20 K photoluminescence spectra.
Effect of N2/H2 Plasma Treatment on the Properties of TiN Films Prepared by Chemical Vapor Deposition from TiCl4 and NH3
Authors: Kim Do-Heyoung , Kim Byung Yup
Published: October 2002

In this work, we studied the effect of N2/H2 plasma post-treatment on the film properties of
TiCl4-based CVD TiN films. The N2/H2 plasma post-treatment was found to strongly affect the
resistivity and chlorine content of the TiN films. This effect became profound for films
deposited after lowering the deposition temperature. The resistivity and the content of chlorine
in the deposits could be reduced by about 70% and 30%, respectively, via the plasma treatment.
However, there was no distinguishable effect of plasma post-treatment on the crystal structure of
the TiN films.
Three Distinct Terraces on a β-(ET)2I3 Surface Studied by Scanning Tunneling Microscopy
Authors: Hashimoto Katsushi , Nakayama Tomonobu , Yoshimoto Noriyuki , Yoshizawa Masahito , Aono Masakazu , Yamaguchi Ichirou
Published: October 2002

Three distinct terraces are observed on the surface of β-(BEDT-TTF)2I3 [BEDT-TTF is
bis(ethylenedithio)tetrathiafulvalene, (C10S8H8)]
by scanning tunneling microscopy. The first and second distinct
terraces are identified as an I3 layer and a BEDT-TTF layer, respectively.
This is verified by the step height and the lateral shift of protrusions
between these terraces. As for the third distinct terrace, we propose a
model of molecular relaxation in the BEDT-TTF layer, which is reasonable in
terms of the interaction between I3 and BEDT-TTF and in terms of the
mutual interaction among BEDT-TTF molecules.
In Situ Growth Monitoring During Metalorganic Chemical Vapor Deposition of YBa 2Cu 3Ox Thin Films by Spectroscopic Ellipsometry
Authors: Shuu'ichirou Yamamoto Shuu'ichirou Yamamoto , Satoshi Sugai Satoshi Sugai , Yasunari Matsukawa Yasunari Matsukawa , Akio Sengoku Akio Sengoku , Hiroshi Tobisaka Hiroshi Tobisaka , Takeo Hattori Takeo Hattori , Shunri Oda Shunri Oda
Published: October 2002

We have investigated in situ spectroscopic ellipsometry in the case of atomic layer-by-layer metalorganic
chemical vapor deposition of YBa2Cu3O
x
(YBCO) thin films. We have demonstrated
the effectiveness of spectroscopic measurement from the relationship between the film properties and
trajectories of the pseudodielectric function of YBCO thin films deposited on SrTiO3 substrates.
We have also demonstrated, in detail, how high-quality crystalline YBCO, formed in the
initial growth stage, can be obtained from the imaginary part of the pseudodielectric function around
4.1 eV. Superconductivity of YBCO films can be estimated during film deposition using optical measurements.
Target Response Times of Liquid Crystal Displays Estimated by Analyzing the Front and Rear Part Gray Levels of Moving Square Patterns
Authors: Chen Guo-Ping , Yamaguti Masahiko , Ito Naoki , Aoki Takayuki , Fukuda Atsuo
Published: October 2002

The slow response of nematic materials causes the blurring of moving pictures on
commercial liquid crystal displays (LCDs). We have estimated the critical response time
τ90 necessary for apparently eliminating the blurring as a function of the gray level
difference ΔG. The estimation is based on the observation that a running square pattern
is hardly perceived when it differs from the background only by one in the 256 gray scale.
For example, τ90 is 300 µs for ΔG=255 and 10 ms for ΔG=3, which can be attained
by using advanced smectic materials with ferro- and/or antiferroelectricity. Comments are
given on another cause of blurring due to the characteristic feature of hold-type displaying in LCDs.
Structural Study of an Al70Ni15Fe15 Decagonal Quasicrystal Using High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy
Authors: Pang Tsai Koh Saitoh
Published: October 2002

High-angle annular dark-field (HAADF) images of a melt-quenched Al70Ni15Fe15 decagonal quasicrystal have been taken using a scanning transmission electron microscope for the first time.
We have found that the alloy is composed of 2-nm-diameter atom clusters with fivefold symmetry.
We have also observed an inversion domain structure. A structural model has been constructed on the basis of the HAADF images and the fivefold cluster of the monoclinic τ2-Al13Co4 approximant model [Saitoh et al. : J. Electron Microsc. 48 (1999) 105].
Antiphase shifts at domain boundaries have been observed directly for the first time.
The present observation has verified the results of high-resolution electron microscopy (HREM) and the dark-field imaging technique obtained by Tsuda et al. [Jpn. J. Appl. Phys. 32 (1993) 129].
Thick and Smooth Hexagonal GaN Growth on GaAs (111) Substrates at 1000°C with Halide Vapor Phase Epitaxy
Authors: Fumio Hasegawa Fumio Hasegawa , Masato Minami Masato Minami , Kenji Sunaba Kenji Sunaba , Takashi Suemasu Takashi Suemasu
Published: October 2002

It was found that hexagonal GaN with a smooth surface can be grown on GaAs (111) substrates at temperatures as high as 1000°C by introducing a GaN layer grown at an intermediate temperature such as 850°C with halide vapor phase epitaxy (HVPE). The surface of the GaN layer grown
at 850°C was rough but it became smooth surface when GaN was grown on it at 1000°C, though sometimes there were several hexagonal pits on the surface. There seems to be some surface flattening mechanism for hexagonal GaN growth at temperatures around or
higher than 1000°C.
The θ-2θ X-ray diffraction (XRD) of the grown layer showed only a hexagonal (0002) peak even for the layer grown at 850°C, but the full width at half maximum (FWHM) of the ω scan was improved by the growth of hexagonal GaN at 1000°C on it.
Cu(In1-xGax)S2 Thin-Film Solar Cells with Efficiency above 12%, Fabricated by Sulfurization
Authors: Ohashi Tsuyoshi , Hashimoto Yoshio , Ito Kentaro
Published: October 2002

An efficient thin-film photovoltaic cell has been fabricated using a
heterostructure consisting of a Cu(In1-x
Ga
x
)S2 absorber layer obtained by
sulfurization of a Cu–In–GaS precursor, a chemical-bath-deposited CdS buffer
layer and an rf-magnetron sputtered In2O3 window layer. The growth of
hillocks was observed on the surface of the absorber layer when the precursor
was heated to the sulfurization temperature (550°C) at the rate of 7°C/min.
According to energy-dispersive X-ray analysis, the hillocks, which cause the
deterioration of cell performance, are composed of an indium-rich compound.
Their growth could be prevented if the heating rate were greatly increased,
particularly in a temperature range between 300°C and 550°C, using a rapid
thermal process. A conversion efficiency of up to 12.3% has been achieved
with a hillock-free Cu(In1-x
Ga
x
)S2 thin film.
The Formation of H2
* by Electron-Irradiation of Hydrogenated Si
Authors: Suezawa Masashi
Published: October 2002

To clarify the formation mechanism of H2
* in Si, we studied the dependence of the concentration
of H2
* on the electron-irradiation dose in hydrogenated Si crystals. Specimens were prepared from
high-purity, B-doped and C-doped Si crystals. They were doped with H by annealing in H2 gas at
1300°C followed by quenching. They were irradiated by 3 MV electrons at room temperature (RT). We measured their
optical absorption spectra at 7 K by an fourier-transform infrared absorption spectroscopy (FT-IR) spectrometer. The intensity of the 1838 cm-1 peak
which is due to H2
* was found to be the weakest in C-doped Si, medium in B-doped Si and the
strongest in high-purity Si. This tendency correlates with that of the intensity of the 2122 cm-1 peak
which is due to a complex of a vacancy and two H atoms. The intensity of the 1838 cm-1 peak
linearly depends on the electron dose at low doses. These results suggest two mechanisms for the
formation of H2
* from H2, namely, a combination of a vacancy and an H2 or a combination of a
Frenkel pair and an H2.
Measurement of Contact Potential of GaAs/AlGaAs Heterostructure Using Kelvin Probe Force Microscopy
Authors: Mizutani Takashi , Usunami Takao , Kishimoto Shigeru , Maezawa Koichi
Published: October 2002

We have shown that the contact potential of i-GaAs/i-AlGaAs heterostructures can be
measured using Kelvin probe force microscopy (KFM). The measured contact potential
difference between GaAs and AlGaAs increases monotonically with increasing AlAs mole
fraction. This dependence does not agree with the model for the ideal interface where the
measured contact potential is dominated by the Fermi level which lies in the midgap of bulk
materials. The results are explained based on the model of the alignment of charge neutrality
level during heterostructure formation.
Observation of Anomalous Heat Release and Helium-4 Production from Highly Deuterated Palladium Fine Particles
Authors: Arata Yoshiaki , Zhang Yue-Chang
Published: October 2002

Observations were made of the anomalous production of 4He atoms as well as
the anomalous heat release when Pd fine particles are highly deuterated inside
an enclosed Pd metal vessel used as a cathode in electrolysis of D2O. A mass
analysis of the remnant Pd powders after the 2000-hr heat production revealed
substantial production of 4He atoms.
Compact High-Density Plasma Source Produced by Using Standing Helicon Waves
Authors: Nisoa Mudtorlep , Sakawa Youichi , Shoji Tatsuo
Published: October 2002

High-density plasmas of the order of 1013 cm-3 are
produced by the m=0 standing helicon wave (SHW)
in a short discharge column (10 cm).
Unlike conventional helicon wave
discharges, high-density plasma production is split into two modes
governed by N=1 and 3 (N is the number of half-wavelengths
in the plasma column) SHWs. The external static magnetic field B
0
dependence of plasma density n
p shows that N=3 SHW can produce a density higher
than N=1 SHW at low magnetic field (∼200 G).
The standing waves are measured and compared using a two-dimensional
wave calculation.
Characterization of the Depth Profile of Electrically Activated Ion-Implanted Impurities by X-ray Photoelectron Spectroscopy and Anodic Oxidation
Authors: Fujii Shinji
Published: October 2002

A new technique for obtaining the depth profile of electrically activated ion-implanted impurities in silicon has been developed. This technique consists
of X-ray photoelectron spectroscopy (XPS) and a combination of anodic
oxidation and chemical removal of the oxide. By applying this technique to
analyse As+- and B+-implanted silicon, the positive shift and the negative
shift of Si 2p photoelectron spectra were observed for As+- and B+-implanted silicon, respectively. Furthermore, the depths of the maximum
energy peak shifts of Si 2p photoelectron spectra are almost coincident
with those of the maximum impurity concentrations measured by Secondary
ion mass spectrometry (SIMS). These results show that the depth profile of
the energy peak shift of Si 2p photoelectron spectra is strongly correlated
with that of electrically activated implanted impurities.
Ab Initio Study of Hydrogen Desorption from Diamond C(100) Surfaces
Authors: Chisato Kanai Chisato Kanai , Kazuyuki Watanabe Kazuyuki Watanabe , Yuji Takakuwa Yuji Takakuwa
Published: October 2002

The desorption potential energies of a hydrogen molecule from hydrogenated
diamond C(100) surfaces have been calculated by the ab initio
pseudopotential method.
We found that a dihydride surface is less stable than a monohydride surface
and that hydrogen desorption can be expected to occur from the dihydride
instead of the monohydride phase of a C(100) surface, from a detailed analysis
of the activation energy for adsorption and desorption of hydrogen molecules
from C(100) surfaces.
The theoretical values of the desorption energies are in good agreement with
the experimental ones.
Mechanical Tuning of the Optical Properties of Plastic Opal as a Photonic Crystal
Authors: Katsumi Yoshino Katsumi Yoshino , Yoshiaki Kawagishi Yoshiaki Kawagishi , Masanori Ozaki Masanori Ozaki , Akira Kose Akira Kose
Published: October 2002

The optical properties of elastic polymer opal prepared utilizing
nanoscale polymer spheres as a flexible photonic crystal have been
examined. The diffraction peak of the polymer opal has been confirmed to be
controllable by the application of mechanical stress, showing its
characteristics as a mechanically tunable photonic material.
Optical Absorption and Photoluminescence Studies of n-type GaN
Authors: Zhao Guang Yuan , Ishikawa Hiroyasu , Jiang Hao , Egawa Takashi , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

The Si-doping dependence of absorption coefficient and photoluminescence (PL) spectra of GaN
grown by metalorganic chemical vapor deposition (MOCVD) was studied at room temperature.
Band gap narrowing and band tailing effect were observed in the absorption spectra of GaN
samples with high carrier concentration. A clear red shift and broadening of the PL emission peak
were observed with increasing dopant concentration, which could also be attributed to the band
tailing effect. This study shows that the band tailing effect plays an important role in determining
the optical properties of Si-doped GaN.
Stability and Application to Multilevel Metallization of Fluorine-Doped Silicon Oxide by High-Density Plasma Chemical Vapor Deposition
Authors: Kishimoto Ken-ichi Koyanagi , Matsumoto Tai-Chan Huo , Okada Norio , Sumihiro Naotaka , Gomi Hideki
Published: October 2002

We report the application of biased
high-density-plasma-chemical-vapor-deposited (HDP-CVD) SiOF films to
multilevel metallization technology. We discuss the reason for the
SiOF film's low dielectric constant and illustrate the optimal
deposition conditions. The fluorine concentration in the HDP-CVD
SiOF film can affect the gap filling characteristics. We observed
that the dielectric constant of this SiOF film is 3.7 for a fluorine
concentration of 7.3 at.%. This film was successfully applied to
intermetal dielectrics and the parasitic capacitance was 13% lower
than that of a SiO2 film.
Method of Adjusting Offset Voltage for the Differential-Type Eddy Current Probe
Authors: Jae-Hoon Choi Jae-Hoon Choi , Shin-Hyuk Kang Shin-Hyuk Kang , Tae-Won Kim Tae-Won Kim , Ho-Jung Hwang Ho-Jung Hwang
Published: October 2002

In this paper, a novel method of adjusting the offset voltage between the first and the second sense coil of an eddy current probe is presented. This method can be applied for the fabrication of an effective differential-type eddy current probe with proper probe structure. A probe made in this way has been tested to determine whether it has a sensitivity high enough to measure a low conductivity material.
Effects of Electrodes on the Electric Properties of Pb(Zr,Ti)O3 Films Deposited by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition
Authors: Su-Ock Chung Su-Ock Chung , Hee-Chul Lee Hee-Chul Lee , Won-Jong Lee Won-Jong Lee
Published: October 2002

The effects of electrodes on the deposition characteristics and electrical properties of lead zirconate titanate (PZT) films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) were investigated. Pt/Ti/SiO2/Si and RuO2/SiO2/Si were used as bottom electrodes (substrates) for PZT capacitors. Pt and
RuO2 were used as top electrodes. The nucleation of the perovskite phase was more difficult on RuO2 substrates than on Pt/Ti substrates, and the PZT films grown on RuO2 substrates tend to have Pb-based second phases. Precise control of the flow rates of metalorganic sources (particularly the lead source) and the introduction of a proper seed layer are required to obtain films of the single perovskite phase and good electrical properties on the RuO2 substrate. An excellent leakage current density of 10-6 A/cm2 at 150 kV/cm was obtained from the Pt(top)/PZT/RuO2(bottom) capacitor with the introduction of a 4 nm-thick Ti-oxide seed layer. The polarization fatigue and current leakage characteristics of the PZT capacitors with four different electrode configurations (Pt ∥Pt,
RuO2 ∥Pt, Pt ∥RuO2, and
RuO2 ∥RuO2) were also investigated. Only the RuO2/PZT/RuO2 capacitor did not show any polarization fatigue even after 1010 cycles, while the other capacitors, whose either top or bottom electrode was Pt, showed distinct polarization fatigues. The RuO2/PZT/RuO2 capacitor, however, showed a leakage current density of as high as 10-4 A/cm2 at 100 kV/cm.
Effect of Multiply Charged Ions on the Refractive Index of Titanium Oxide Films and an Application to Decorative Films
Authors: Akira Suzuki Akira Suzuki
Published: October 2002

In previous reports, higher charged ions are induced by higher voltage discharge, and harder films such as TiN, (Ti,Al)N and TiC are obtained by the higher voltage discharge method. The effect of multiply charged ions was confirmed in previous experiments. Multiply charged ions will affect physical properties other than hardness. In this study, the refractive index of titanium oxide films is investigated as a function of the discharge voltage. A high-refractive-index film is obtained by the high-voltage discharge method under various deposition conditions. The high-refractive-index film is applied to a reflection-increasing film, e.g., reflector for optical pumping of a laser beam. A reddish film can be obtained by depositing TiCN film; the film is applied to decorative goods to achieve a copper-like color. However, the reddish color of TiCN is inferior to that of films which are obtained by anodic oxidation or painting. If the reddishness of TiCN film is increased, the frequency of application to decorative goods is expected to increase. In this study, TiO2 film is applied to increase the reddishness of TiCN film for use in decorative goods. By depositing TiO2 film on TiCN, the reddishness is successfully increased from 8.4 to 34.9 with respect to the a
* value which expresses red in the L*a*b* color space.