bluuebunny/crossref_metadata_2025 huggingface dataset:
Current-Voltage Characteristics and Conductivity of Metal-Insulator-Metal (Ti/TaOx/Ta) Type Thin-Film Diode
Authors: Hirai Takanori , Morita Hiroshi , Tasaka Masayasu
Published: October 2002

The non-linearity coefficient β of the Poole-Frenkel equation was
examined for an actual thin-film diode (TFD) with a Ti/TaO
x
/Ta element. When the
value of β estimated from the plot of the activation energy (E
a)
against the root of applied voltage (V
1/2) was used, the Poole-Frenkel equation
could be applied to the analysis of the actual TFD elements. The coefficient β
obtained by the above method became smaller and the depth of the donor level (φ)
in the oxide film (TaO
x
) became apparently shallower when the impurity
concentration was high on the electron injection side in the oxide. Thus, the coefficient
β took different values with the applied voltage direction when the impurities
were asymmetrically distributed in the oxide. The coefficient β also varied with
the difference of the anodizing solution species.
Photoluminescence Analysis of Plasma-deposited Oxygen-rich Silicon Oxynitride Films
Authors: Noma Takashi , Seol Kwang Soo , Fujimaki Makoto , Kato Hiromitsu , Watanabe Takashi , Ohki Yoshimichi
Published: October 2002

Photoluminescence spectra were observed for hydrogenated oxygen-rich silicon oxynitride films with different N/O ratios, deposited by plasma-enhanced chemical vapor deposition. In the sample with a small ratio of N/O, two luminescence bands at 4.4 and 2.7 eV originated from silicon homobonds in SiO2 were observed, while a luminescence band at 2.6–2.9 eV which has very similar properties to the one observed in SiN
x
was observed in the sample with a large ratio of N/O. The results of Fourier-transform infrared spectroscopy, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy indicated that the luminescence band at 2.6–2.9 eV results from Si–N bonds in the films and that the present films have regions where Si–N bonds gathered.
Effects of Chemical Composition and Morphology of Substrate Surfaces on Crystallinity of Ultrathin Hydrogenated Microcrystalline Silicon Films
Authors: Mori Kazuteru , Yasuda Tetsuji , Nishizawa Masayasu , Yamasaki Satoshi , Tanaka Kazunobu
Published: October 2002

Hydrogenated microcrystalline silicon (µc-Si:H) films of 10 nm thickness were prepared by the plasma-enhanced chemical vapor deposition method on glass substrates that had been coated by a layer composed of Si, O, and N. The chemical composition of this layer was changed systematically, and the resultant changes in the crystallinity of the µc-Si:H films were investigated using Raman scattering spectroscopy. We have found that SiN
x
layers inhibit nucleation of microcrystalline Si and the films deposited on them are dominated by an amorphous component, regardless of their stoichiometry. Substrate surfaces rich in Si–O bonds are preferable for the formation of high-quality µc-Si:H films. It has been also found that the morphology of the coated layers does not affect the crystallinity of the µc-Si:H films.
Low-Frequency Relaxation Modes of Surface-Stabilized Ferroelectric Liquid Crystal
Authors: Jong-Min Wang Jong-Min Wang , Jong-Jean Kim Jong-Jean Kim
Published: October 2002

Very broad low-frequency dielectric data of a surface-stabilized ferroelectric liquid crystal (SSFLC) sample in the frequency (ω) domain was analyzed by the Tikhonov regularization method to derive three distinctive modes of relaxation in time (τ) domain spectra corresponding to the X-, D- and L-modes.
A Surface-Silylated Single-Layer Resist Using Chemical Amplification for Deep-Ultraviolet Lithography: I. Limited Permeation of Si Compounds from Vapor Phase*
Authors: Sugita Kazuyuki , Ikagawa Masakuni , Harada Kieko , Kushida Masahito , Saito Kyoichi
Published: October 2002

A single thick layer of poly(vinyl phenol) on a substrate was
surface-silylated by exposure to hexamethyl-disilazane vapor to obtain
a bilevel structure. Silicon atoms were effectively incorporated into
the surface sublayer by limited vapor permeation and reaction with –OH
to form –O–Si(CH3)3. The oxygen reactive-ion-etching (RIE)
durability of the silylated sublayer of 50–150 nm thickness was
10–50 times as high as that of the unsilylated bulk layer. The
surface-silylated single-layer (SSS) resist which contained a small
amount of onium salt was patterned by 7–20 mJ/cm2
deep-ultraviolet (DUV) exposure, postexposure bake, wet development
with aqueous tetramethyl-ammonium hydroxide, and dry development in an
O2 RIE chamber. The surface sublayer in the exposed area was
removed by wet development to form a shallow, recessed mesh
pattern. When it was plasma-developed, the thick bulk layer in the
exposed area was blanked to the substrate to form a positive-tone
image with a high aspect ratio.
Low-Stress Molybdenum/Silicon Multilayer Coatings for Extreme Ultraviolet Lithography
Authors: Shiraishi Masayuki , Ishiyama Wakana , Oshino Tetsuya , Murakami Katsuhiko
Published: October 2002

Modified molybdenum/silicon (Mo/Si) multilayers were deposited by ion beam sputtering (IBS). We obtained low-stress multilayers by sub-multilayering each Mo-layer into a trilayer of Mo/Ru (ruthenium)/Mo, and by argon (Ar) ion beam polishing (IBP) after each Mo-layer deposition. Conventional Mo/Si multilayers have a compressive stress of about -450 MPa, while the low-stress multilayers we have developed have a tensile stress of +14 MPa, on an average. Low-stress multilayers have similar reflectances to those of conventional Mo/Si multilayers, and exhibit no significant temporal changes in the layer period and the stress for up to one year. The method used for stress reduction is not a heating process such as annealing, thus it does not cause irreversible deformation of the precisely-figured mirror substrates of optics. It is expected that the application of low-stress multilayers to mirrors will make it possible to compose optics without worsening the optical properties due to deformation of substrates by the stress of multilayer coatings.
Automatic Dose Optimization System for Resist Cross-Sectional Profile in a Electron Beam Lithography
Authors: Hirai Yoshihiko , Kikuta Hisao , Okano Masato , Yotsuya Tsutomu , Yamamoto Kazuya
Published: October 2002

A computer-aided dose optimization system to obtain a modified resist cross-sectional profile is demonstrated based on resist development simulation and an iteration procedure of the exposure dose profile for a positive electron beam resist. The absorbed energy in the resist by the electron beam exposure is evaluated by conventional Monte-Carlo simulation and the resist cross-sectional profile after development is predicted by a cell removal model. The exposure dose profile is optimized by an iteration procedure based on the predicted resist development profile. The exposure dosages at each point are corrected based on the difference of the average absorbed energy density between the desired developed surface and the predicted profile by the resist development simulation. The system is applied for blaze pattern fabrication for diffractive optical elements and a fine blaze pattern is successfully obtained.
Critical-Dimension Controllability of Chemically Amplified Resists for X-Ray Membrane Mask Fabrication
Authors: Ezaki Mizunori , Nakayama Yoshinori , Kikuchi Yukiko , Tsuboi Shinji , Watanabe Hiroshi , Aoyama Hajime , Matsui Yasuji , Morosawa Tetsuo , Ohki Shigehisa , Saito Kenichi , Matsuda Tadahito
Published: October 2002

The key issues in highly precise X-ray mask fabrication are the high-performance electron beam writer and the mask process on a thin membrane. By the combination of 100 kV electron beam system EB-X3 and highly sensitive chemically amplified resist, the high resolution and the excellent critical-dimension (CD) uniformity of 50–100 nm line-and-space and isolated-space features were obtained with no proximity correction. Temperature uniformity of various hot plate bakers during the post-exposure bake process and CD controllability of pattern size with chemically amplified resists were studied and the 3σ variation of pattern size written in a membrane using chemically amplified resists was reduced to less than 10 nm with an optimized hot plate baker. As a result, the e-beam sensitivity and writing time for 4G-bit level ULSI patterns of chemically amplified resist were reduced to less than half of those with conventional ZEP-520 resist, while the resolution capability and CD accuracy of the membrane mask with chemically amplified resist UV6-SL were almost equal to those with ZEP-520.
Novel Organic Bottom Antireflective Coating Materials for 193 nm Lithography
Authors: Jung Min-Ho , Hong Sung-Eun , Jung Jae-Chang , Lee Geunsu , Baik Ki-Ho
Published: October 2002

We designed novel hybrid type bottom antireflective coating (BARC) materials for ArF lithography. The optimum extinction coefficient (k) value of the new organic BARC materials (HEART004) is 0.71 at a 32 nm film thickness. Its plasma etch rate is higher than that of ArF photoresist under Cl2/O2 plasma etch conditions. The critical dimension (CD) uniformity of 0.13 µm L/S patterns could be controlled below 10 nm and the etch bias, which represents the CD difference before and after BARC etching, could be less than 10 nm. Our new organic BARC materials show a good compatibility with both (meth)acrylate-type photoresist (PAR101, PAR710) and cycloolefin/maleic-anhydride-type photoresist (DHA1001) without any undercut or footing.
Control of Crystal Structure and Ferroelectric Properties of Pb(ZrXTi1-X)O3 Films Formed by Pulsed Laser Deposition
Authors: Fujita Hirotake , Goto Satoru , Sakashita Mitsuo , Ikeda Hiroya , Sakai Akira , Zaima Shigeaki , Yasuda Yukio
Published: October 2002

Pb(Zr
X
Ti1-X
)O3 (PZT) thin films on Pt/SiO2/Si substrates formed by pulsed laser deposition (PLD) and subsequent rapid thermal annealing (RTA) have been investigated. X-ray diffraction (XRD) and atomic force microscopy showed that the crystalline structure and the crystallographic orientation of PZT films after RTA, sensitively depended on the microstructure of as-deposited films. The preferentially (100)-oriented perovskite PZT films forming a trigonal structure were obtained from the as-deposited films that had contained small grains having a pyrochlore structure. This type of perovskite structure was found to depend also on the oxygen pressure during PLD. Chemical composition analysis by X-ray photoelectron spectroscopy clearly revealed the characteristics of a Zr-rich composition which induced the trigonal phases in the films, which were consistent with the XRD results. The capacitors made from these films showed large remanent polarization.
0.04 µm Domain Expansion Readout for the Magnetic Amplifiying Magneto Optical System
Authors: Awano Hiroyuki , Sekine Masaki , Tani Manabu , Kasajima Nobuko , Ohta Norio , Mitani Kenichiro , Takagi Naoyuki , Sumi Satoshi
Published: October 2002

Read/write characteristics of the magnetic amplifying magneto optical
system (MAMMOS) with alternative readout fields such as carrier to
noise ratio (C/N), eye pattern, jitter
and bit error rate (BER), are investigated with a 640 nm wavelength laser diode and 0.55
numerical aperture of the objective lens. The C/N value of 0.12 µm is 50 dB and is independent
of the mark length. A very clear eye pattern was observed. The results show that the jitter
value is less than 3% compared with the window width and it is only dependent on the
switching speed of the readout field. The error rate is improved by using a thin recording layer
of 50 nm in thickness. The minimum domain length which yields a BER
of less than 1×10-4 is
0.045 µm (45 nm); the minimum space length is 0.10 µm (100 nm). These results are confirmed
at a track pitch of about 0.40 µm. By using a digital versatile disk (DVD) pickup, the areal
density can be estimated to be about 23 Gbit/in2 with the user
data capacity of 30 GB/120 mmφ.
By using a 400 nm blue laser diode, these values are estimated as
59 Gbit/in2 and 77 GB/120 mmφ.
Recrystallization Dynamics of Phase Change Optical Disks with a Nitrogen Interface Layer
Authors: Trappe Cyril , Béchevet Bernard , Hyot Bérangère , Winkler Olaf , Facsko Stefan , Kurz Heinrich
Published: October 2002

The recrystallization velocity of a phase change material is measured in real time by observing
the reflected laser power during the interaction of the laser with the sample. This technique is
applied to compare the recrystallization behavior of phase change optical disk media with and
without a nitride interface layer. It is shown that the enhanced cyclability induced by the
nitride interface layer is correlated to an enhancement of the recrystallization velocity. The
experimental determination of temperature profiles induced by laser pulses, combined with
the numerical integration of the crystallization rate equations, leads to a quantitative
interpretation of the observed recrystallization dynamics.
Cover Layer Technology for the High-Numerical-Aperture Digital Video Recording System
Authors: Decré Michel M. J. , Vromans Piet H. G. M.
Published: October 2002

It is experimentally demonstrated that two techniques allow the manufacture of a 100-µm-thick cover layer within the requirements of the digital video recording system, that uses a high numerical aperture of 0.85 at 650 nm wavelength. The first technique uses spin-coating of an ultraviolet curable resin and the second is the ultraviolet bonding of a 100-µm-thick
polycarbonate sheet. Both techniques guarantee thickness variations within ±3 µm, and display disc radial and tangential tilts
within sufficient margins.
Partial Response Maximum Likelihood for Optical Data Storage Using Simple Optical Equalizers
Authors: Jepson Stephen D. , Nutter Paul W. , Wright C. David
Published: October 2002

The effects of introducing shading bands into the collector path of optical storage devices
to equalize optically the signal to a partial response target have been investigated. A software
simulation of the optical readout process and the partial-response maximum-likelihood
(PRML) read channel have been developed and used to evaluate different channel
configurations. It is shown that optical filtering can be used to eliminate the requirement for
digital filtering in the PRML channel.
A Comparison of Two Coding Schemes for Generating DC-Free Runlength-Limited Sequences
Authors: Wilson Wang Yong Hong , Immink Kees A. S. , Xi Xu Bao , Chong Chong Tow
Published: October 2002

We report on the performance assessment of two methods for
generating DC-free runlength-limited sequences. Redundant bits
used to optimize the low-frequency properties are multiplexed with
user data or encoded data. In the first method, the redundant bits
are multiplexed with the channel bits generated by a (d,k)
encoder. In the second method, on the other hand, the redundant
bits are multiplexed with the user data. i.e. prior to application
of the (d,k) encoder. The second method can only be used if the
(d,k) encoder satisfies the parity preserving condition, i.e.,
data words and code words of that code must have the same parity.
In the article we describe in detail an example of a parity
preserving (1, 8) code.
Experimental Verification of Revised Roles Played by Helium and Nitrogen in CO2 Lasers
Authors: Chang Sheng-Hsiung , Cheng Chao-Chia , Chang Ming-Feng , Tsai Hung-Sheng , Liu Hai-Pei
Published: October 2002

In one of our previous papers we presented a fast axial flow
CO2 laser excited by 150 kHz resonant silent discharge. The
optimized gas mixing ratio of this setup was CO2 :
N2 : He = 1 : 22 : 5. This ratio was very peculiar
but the laser efficiency thus achieved was optimized and comparable to
that of other fast axial flow CO2 lasers. We have already put
forth some preliminary postulations explaining the reason for this
particular result; nevertheless in order to obtain a clearer insight
into this laser we designed and carried out a series of
experiments. The data collected were helpful for understanding why
N2 is more important than He, and what roles they play in such a
laser system.
Dynamics of Output Spectra within a Single Laser Pulse from a Line-Narrowed Excimer Laser
Authors: Enami Tatsuo , Hori Tsukasa , Ohta Takeshi , Mizoguchi Hakaru , Okada Tatsuo
Published: October 2002

We describe the dynamic behavior of spectral line-narrowing
during a single laser pulse generated from a line-narrowed KrF excimer
laser used in optical lithography. To study the details of the
dynamics, a spectral monitoring system, composed of a Fabry-Perot
interferometer, a streak camera, and a numerical simulation code was
developed. In the laser studied, the spectral bandwidth of 1.5 pm in
full width at half maximum (FWHM) at the beginning of the pulse was
narrowed to 0.8 pm (FWHM) with the wavelength selective elements
having a passive transmission bandwidth of about 2.9 pm (FWHM). The
results of the numerical calculations were in reasonable agreement
with the experimental results, and showed that the time-integrated
line-width in the present laser system was narrowed only to 40% of
the transmission bandwidth of the spectral selective elements in the
cavity.
Track Center Servo and Radial Tilt Servo System for a Digital Versatile Rewritable Disc (DVD-RAM)
Authors: Yamada Shin-ichi , Nishiwaki Seiji , Nakamura Atsushi , Ishida Takashi , Yamaguchi Hiroyuki
Published: October 2002

In the push-pull tracking error signal, which is generally used for rewritable discs, detection error occurs due to disc radial tilt. We have developed a track center detection method in which the center of a track is accurately detected using the complementary allocated pit address (CAPA) of a digital versatile rewritable disc (DVD-RAM). The track center servo corrects the tracking deviation caused by the detection error. We have also developed a method for detecting the disc radial tilt based on the fact that the level of the push-pull tracking error signal indicates the amount of disc radial tilt when the track center servo is in operation. The developed servo system was introduced in a 4.7-G byte DVD-RAM disc drive, and it has been confirmed that jitter deterioration during reproduction was reduced to 0.5% or lower in the range of ±0.5 degree of disc radial tilt.
Aspherical Supersphere Solid Immersion Lens for Near-Field Optical Recording
Authors: Minyu Liu , Baoxi Xu , Chong Chong Tow , Gaoqiang Yuan , Yang Bah Chee
Published: October 2002

An aspherical supersphere solid immersion lens (ASSIL) is proposed to increase optical system
misalignment tolerance. A few aspherical surfaces are designed to meet different critical aberration
requirements. Simulation results show that the tolerances have clearly improved in two assembling
directions.
High-Speed Optical Library System Using Digital Versatile Disk Random Access Memory
Authors: Tanabe Takaya , Ura Tetsu , Yamamoto Manabu
Published: October 2002

A high-data-transfer-rate optical storage system using a
redundant array of inexpensive libraries (RAIL) has been developed
and tested. It incorporates multiple libraries, where each library
consists of dual digital versatile disk (DVD) random access memory
(RAM) drives and a single robotic hand and holds 2.6 GB DVD disks.
To increase the reliability of data storage and at the same time to
eliminate the need for read-after-write verification, which doubles
the recording time, a redundant array of inexpensive drives (RAID) 4
algorithm is implemented in the control unit of the storage system.
Data sent by the host is transferred to a control unit, which
stripes the data into five data groups plus one parity unit. The
striped and parity data is sent to individual libraries and written
to the DVD disks. This system writes and retrieves data with a
transfer rate of approximately 6 MB/s, using write and read control
methods that minimize the data striping overhead. This reliable
library system can be used for networked multimedia applications.
Theoretical Analysis of Recording Light Distribution in Phase-Change Near-Field Recording Using Solid Immersion Lens
Authors: Chong Chong Jingfeng Liu , Baoxi Xu Baoxi Xu
Published: October 2002

We investigate the behavior of recording light in a phase-change near-field recording system in the presence of a solid immersion lens (SIL) and an optical disk. The relationship of the recording light density with the air gap and the disk structure is analyzed in detail, together with the beam spot profiles. Moreover, the coupling efficiency in the presence of the optical disk is calculated. It is found that the behavior of the recording light depends strongly on the air gap and the entire optical disk structure.
Carrier Dynamics and Terahertz Radiation in Photoconductive Antennas
Authors: Piao Zhisheng , Tani Masahiko , Sakai Kiyomi
Published: October 2002

In this paper we report the calculations of terahertz radiation from biased photoconductive antennas. The calculations are based on the Drude-Lorentz theory of carrier transport in semiconductors. The calculation model takes into account the interaction between electrons and holes, trapping of carriers in mid-gap states, scattering of carriers and dynamical space-charge effects. Our calculation results indicate that, when a biased photoconductive antenna is pumped by femtosecond laser pulses to generate THz radiation, a major portion of the radiation results from the ultrafast change of the carrier density. The results also show that the local electrical field oscillates and induces electromagnetic radiation at high carrier generation density. When a photoconductive antenna is used as a detector, the detected THz signal deviates considerably from the THz pulse incident upon the photoconductive antenna.
A Near-Field Recording and Readout Technology Using a Metallic Probe in an Optical Disk
Authors: Fuji Hiroshi , Tominaga Junji , Men Liqiu , Nakano Takashi , Katayama Hiroyuki , Atoda Nobufumi
Published: October 2002

We demonstrate a new near-field technology that uses a metallic
probe in an optical disk. The metallic probe is produced in a
focused spot on a readout layer composed of silver oxide. However
the metallic probe is not transparent to far-field light, near-field
light generated around it. Therefore, a mark of less than 100 nm in
length could be recorded and reproduced by detecting the scattered
light around the metallic probe and the mark.
Early Increase in Resistance during Electromigration in AlCu-plugged Via Structures
Authors: Hoshino Kazuhiro
Published: October 2002

This paper reports on the electromigration (EM) failure mechanism in
AlCu-plugged via holes. Based on an observed increase in the via chain resistance and
cross-sectional analysis of the damaged vias, an early failure and a normal failure
were identified during the EM tests. The early failure occurred in the Al plug at the
cathode side, and was attributed to void growth in the Al plugs during EM. The normal
failure occurred not in the Al plugs, but on the Al lines, and exhibited a three-stage
increase in resistance. An early increase in resistance of about 5% was found in the
normal failure during EM. Failure sites were observed around the terminated via
using the optical-beam-induced resistance change (OBIRCH) method. At the failure
sites, crystallization of CuAl2 was observed at the anode via using transmission
electron microscope (TEM). The early increase in resistance caused by CuAl2
crystal formation at the anode was brought about by using the AlCu via plug. This
resistance increase is a serious problem for the small AlCu via connected to long or
wide AlCu interconnects.
The Analysis of Slip Extension and Induced Stress in 300 mm Diameter Wafers on Three-point Symmetrical Support
Authors: Fukuda Tetsuo , Hikazutani Ken-ichi
Published: October 2002

We performed slip tests using 300 mm diameter wafers on an inner three-point
symmetrical boat in a batch-type vertical furnace. The maximum temperatures
necessary to avoid a slip are shown for low-oxygen content and heavily boron-doped
wafers. After studying the dependence of slip extension on wafer-annealing time at
temperatures above 1100°C, we discuss the influence of bending stress on slip
extension. It is emphasized that inner three-point symmetrical support has an
advantage that the resolved shear component of thermal stress is considerably lower
than that in the peripheral support as well as that of bending stress is.
Creation of Highly Oriented Freestanding Carbon Nanotube Film by Sublimating Decomposition of Silicon Carbide Film
Authors: Shimizu Toshiki , Ishikawa Yukari , Kusunoki Michiko , Nagano Takayuki , Shibata Noriyoshi
Published: October 2002

Freestanding carbon nanotube films were created by sublimating decomposition of silicon carbide films, which were grown on thin silicon-on-insulator (SOI) substrates by chemical vapor deposition with alternating gas supply of SiH2Cl2 and C2H2. The sublimating decomposition of silicon carbide is performed by annealing the SiC film at 1600°C in vacuum (1×10-2 Pa). The carbon nanotubes were highly oriented perpendicular to the single-crystal SiC(111) film.
Visible Photoluminescence from Si+-Implanted SiO2 Films after High-Temperature Rapid Thermal Annealing
Authors: Tsai Jen-Hwan , Yu Ann-Ting , Sheu Bor-Chiou
Published: October 2002

Two photoluminescence (PL) bands were observed in 4×1015 cm-2-fluence-Si+-implanted 100-nm-thick SiO2 films after rapid thermal annealing (RTA)
at 950–1150°C with 2–4 eV excitation. The PL band at 2.2 eV was excited by 3.8 eV photons in
the films after RTA in dry nitrogen while the other band at 1.9 eV
was excited by 2.5 eV photons in the films after isochronal RTA in wet
nitrogen. Moreover, the origin for the 2.2 eV energy band was found to be the same as that of the Eδ
′
center. The origin of the 1.9 eV band could be ascribed to the non-bridging oxygen hole centers
(NBOHC). The latter was more stable even at high temperatures and
showed a stronger PL intensity than the former.
High-Resolution Double Self-Pumped Phase Conjugations with +c-face Incident Configuration in a BaTiO3 Crystal
Authors: Chen Tzu Chiang , Chang Chi Ching , Tang Li Chuan , Yau Hon Fai
Published: October 2002

The geometry of creating two stable self-pumped phase-conjugate outputs in one photorefractive BaTiO3 crystal is demonstrated. This novel geometry provides two phase-conjugate images with a resolution as high as 4 µm (or 114 lp/mm). The reflectivity versus the angle of the incident beam is also investigated.
Atomic Resolution Imaging on Si(100)2×1 and Si(100)2×1:H Surfaces with Noncontact Atomic Force Microscopy
Authors: Kousuke Yokoyama Kousuke Yokoyama , Taketoshi Ochi Taketoshi Ochi , Akira Yoshimoto Akira Yoshimoto , Yasuhiro Sugawara Yasuhiro Sugawara , Seizo Morita Seizo Morita
Published: October 2002

We investigate the difference in atomic resolution images between the Si(100)2×1 reconstructed surface with a dangling bond and the Si(100)2×1:H monohydride surface without a dangling bond using noncontact atomic force microscopy. On the Si(100)2×1 surface, the distance between bright spots is 3.2 ±0.1 Å, which is larger than that between silicon atoms. On the Si(100)2×1:H surface, the distance between bright spots is 3.5 ±0.1 Å, which is in good agreement with that between hydrogen atoms. For the first time, individual hydrogen atoms are resolved. This means that the distance between measured bright spots forming dimers is increased by the hydrogen termination.
Direct Measurement of Sheath Electric Field Distribution in Front of Substrate in Electron Cyclotron Resonance Plasma by Laser-Induced Fluorescence Technique
Authors: Watanabe Mahiko , Takiyama Ken , Oda Toshiatsu
Published: October 2002

The first reported direct measurement of a sheath electric field
structure was made in front of a substrate in an electron cyclotron
resonance plasma flow in a magnetic field using polarized
laser-induced fluorescence spectroscopy. A linear decrease of the
electric field strength was found relative to the distance from the
substrate surface. The sheath thickness was proportional to the
square root of the applied bias voltage. The experimental results
can be explained by a simple sheath model.
Application of In Situ-Formed Metallic-Fiber-Reinforced Copper Matrix Composites to Cables Used for Robots
Authors: Miyake Koichi , Hanzawa Noriko , Ninomiya Ryuji , Takahara Hidefusa , Kobayashi Sigeru , Raabe Dierk
Published: October 2002

The newly developed cable used for a robot was shown to have its
excellent durability against cyclic and flexural deformation, when
composed of in situ-formed metallic-fiber-reinforced copper
matrix composites (in situ MMCs) as electric conductors,
where the metallic fiber was, for example, niobium or chromium. The
durability determined by a cyclic and flexural deformation test was
one order magnitude higher than that of a conventional cable whose
electric conductor was composed of a Cu-0.3 mass%Sn alloy. A
noteworthy feature observed in the present in situ-formed
chromium fiber is that the mean size of the formed chromium ribbon
like fiber was below 1.0 µm in width and around 10 nm in
thickness, which could result in an extremely high elastic limit of
beyond 1000 MPa. The superior durability of the present robot cable
is mainly due to the fact that robot operations are in the elastic
region of the present electric conductors. The electric conductivity
of samples was around 70%IACS (International Annealed Copper
Standard).
Reliability of High-Frequency Operation of Low-Temperature Polysilicon Thin Film Transistors under Dynamic Stress
Authors: Yukiharu Uraoka Yukiharu Uraoka , Tomoaki Hatayama Tomoaki Hatayama , Takashi Fuyuki Takashi Fuyuki , Tetsuya Kawamura Tetsuya Kawamura , Yuji Tsuchihashi Yuji Tsuchihashi
Published: October 2002

The reliability of low-temperature poly-Si under dynamic stress was evaluated. A decrease in the mobility and the ON current was observed under the dynamic stress. We found that the degradation depends strongly on falling time and frequency. Based on these findings, degradation was found to be induced by high electric field during pulse fall duration. This degradation is dominated by hot electrons and can be improved by adopting a lightly doped drain (LDD) structure.
Vanadium Ion Implanted Guard Rings for High-Voltage 4H-SiC Schottky Rectifiers
Authors: Tomoaki Hatayama Tomoaki Hatayama , Tomoaki Yoneda Tomoaki Yoneda , Toshitake Nakata Toshitake Nakata , Masanori Watanabe Masanori Watanabe , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

Vanadium ion (51V+) implantation using a low dose in the range of 1012–1013 cm-2 was applied to form a high-resistivity guard ring for high-voltage 4H-SiC Schottky rectifiers. Breakdown voltages were successfully increased by the formation of a 51V+-implanted guard ring. To investigate the effects of the implanted guard ring, the width and depth were varied by the size of the mask pattern and the maximum implantation energy, respectively. With a 150 µm-wide and 0.5 µm-deep 51V+-implanted guard ring, a nearly ideal breakdown voltage of 1630 V was achieved using a 10 µm-thick epilayer.
Novel Fabrication Process of Organic Microcrystals Using Microwave-Irradiation
Authors: Baba Koichi , Kasai Hitoshi , Okada Shuji , Oikawa Hidetoshi , Nakanishi Hachiro
Published: October 2002

The reprecipitation method is a useful technique for the fabrication of organic microcrystals. We have further developed this method for the preparation of some well-defined and monodispersed organic microcrystals by utilizing microwave irradiation.
High-Quality InGaN Films Grown on Ga-Polarity GaN by Plasma-Assisted Molecular-Beam Epitaxy
Authors: Shen Xu-Qiang , Ide Toshihide , Shimizu Mitsuaki , Hara Shiro , Okumura Hajime
Published: October 2002

High-quality InGaN films were successfully grown on a Ga-polarity GaN underlayer by plasma-assisted molecular-beam epitaxy (rf-MBE) with good reproducibility. X-ray diffraction (XRD) results showed that there was no phase separation of In with the In mole fraction up to 0.36. Intense photoluminescence emissions from the InGaN films were obtained. Clear evidence was obtained for the difference in the quality between InGaN films grown on the Ga-polarity and those grown on N-polarity GaN buffer layers, in which the Ga-polarity GaN buffer is preferred. Our results provide a basis for fabricating high-quality InGaN/(Al, Ga)N heterostructures for optical and electronic device applications by rf-MBE.
New Potential of a Direct Laser-Diode-Pumped Yb:YAG Laser
Authors: Fujita Masayuki , Sano Eisaku , Kubo Ryouichi , Kawashima Toshiyuki , Yamanaka Masanobu , Izawa Yasukazu , Nakai Sadao , Yamanaka Chiyoe
Published: October 2002

A wide range of tunability (1030–1100 nm) was demonstrated with an Yb:YAG laser crystal. The measured bandwidth of Δν∼70 nm corresponds to the Fourier-limited pulse width of Δt∼17 fs. This result indicates a new potential of the Yb:YAG as a direct laser-diode (LD)-pumped femtosecond laser amplifier.
Effects of Post-Deposition Heat Treatment on the Properties of Low Dielectric Constant Plasma Polymerized Decahydronaphthalene Thin Films Deposited by Plasma-Enhanced Chemical Vapor Deposition
Authors: Yang Jaeyoung , Shim Cheonman , Jung Donggeun
Published: October 2002

Effects of post-deposition heat treatment on the properties of plasma polymerized decahydronaphthalene (PPDHN) thin films were studied. Heat treatment at 150°C and 250°C decreased the relative dielectric constant k from 2.80, the k value of the as-deposited film, to 2.52 and 2.63, respectively. With the increase of the temperature of heat treatment, the thermal stability of the PPDHN thin film improved. Changes of the k value and thermal stability were related to changes of C-H, C=O and O-H group density.
Influence of Substrate Temperature to Prepare C-Axis-Oriented AlN Films on Rotated Y-cut Quartz(ST-Quartz)
Authors: Wu Long , Wu Sean , Chure Ming-Cherng
Published: October 2002

Highly c-axis-oriented AlN films were successfully prepared on rotated Y-cut quartz(ST-Quartz)
substrates by rf magnetron sputtering in this research. The dependence of
the substrate temperatures and the material characteristics of the films
(crystalline structure and micro morphology) were investigated. The highly
c-axis-oriented AlN films appeared at the higher substrate temperatures and
the best orientation of the films were prepared at 400°C in this
research.
Fourier Expansion Method for Noncontact Atomic Force Microscopy Image Simulations – Application to Si(111) √3×√3–Ag Surface
Authors: Naruo Sasaki Naruo Sasaki , Hideaki Aizawa Hideaki Aizawa , Masaru Tsukada Masaru Tsukada
Published: October 2002

A Fourier expansion method is proposed to simulate noncontact
atomic force microscopy images. The three-dimensional distribution of
the tip-surface interaction force obtained by the first-principles
density functional calculations is efficiently used for calculating
frequency shifts of the resonant frequency. The two-dimensional
periodicity of the surface, which is the basis of this method, can be
rigorously described. For a case study of this method, we
theoretically simulate noncontact atomic-force microscopy (NC-AFM) images of a
Si(111) √3×√3 R 30°–Ag rigid
surface with the first-principles density functional
calculation. Force spectroscopies and AFM images for different tip
heights are calculated.
Dislocation-Free Czochralski Si Crystal Growth without the Dash-Necking Process: Growth from Undoped Si Melt
Authors: Taishi Toshinori , Huang Xinming , Fukami Tatsuo , Hoshikawa Keigo
Published: October 2002

Dislocation-free Si crystals have been grown successfully by the
Czochralski (CZ) method without the Dash-necking process. It was
found that the boron concentration limit in the seed for no
dislocation formation due to thermal shock was 1×1018 atoms/cm3, and the maximum admissible discrepancy of
boron concentration in the seed and in the crystal was 7×1018 atoms/cm3 for no dislocation formation in the crystal
due to the lattice misfit. Consequently, it is revealed that
dislocation-free CZ-Si crystals can be grown from undoped Si melt
without the Dash-necking process when a seed with a suitable boron
concentration is used.
Optical Signal Inverter Based on Injection Locking of Laser Diode for Directly Modulated Optical Pulses
Authors: Fukushima Takehiro , Hanada Kazunari , Sakamoto Toyokazu
Published: October 2002

We constructed an optical signal inverter based on the injection
locking of a laser diode and observed signal inversion for the pulse
train emitted from a directly modulated laser diode. The inverter
consists of two laser diodes and narrow-band Fabry-Perot
etalons. The optical pulse train emitted from the master laser was
injected into the slave laser whose free-running wavelength was
about 3 nm away from the master laser oscillating wavelength. The
free-running component of the slave laser output shows the inverted
waveform of the injected pulse train. The optical signal inverter is
suitable for high output power operation.
Intensity Enhancement of Auger-Free Luminescence in BaF 2 and CsCl by Acceleration Voltage of Electron-Beam Excitation
Authors: Hisashi Yoshida Hisashi Yoshida , Masato Hayashi Masato Hayashi , Minoru Itoh Minoru Itoh
Published: October 2002

Cathodoluminescence of BaF2 and CsCl has been studied at room temperature by changing the applied acceleration voltage from 2 to 15 kV. A two-photon emission process takes place in these materials. One is an ordinary interband luminescence (IBL) between the conduction and valence bands. The other is a specific type of luminescence, the so-called Auger-free luminescence (AFL), between the valence and outermost-core bands. It is found that the intensity of AFL enhances with increasing acceleration voltage, compared to that of the IBL. The present result is important and useful for improving the quantum yield of light-emitting devices.
pH Dependence of Luminescence in Dye-Doped Sol-Gel Coating Film
Authors: Takahashi Yoshihiro , Maeda Akinori , Kojima Kenzo , Uchida Kenji
Published: October 2002

A rhodamine 6 G-doped sol-gel coating film did not show spectral or intensity
changes in absorption or fluorescence in the acid-base equilibrium of immobilized dyes.
When rhodamine 6 G was doped together with coumarin 6 and fluorescein in sol-gel
coating films, its emission showed an increase in intensity with the increase of pH.
These observations were related to energy transfer from coumarin 6 and fluorescein to
rhodamine 6 G. The sensitivity region of this emission intensity to pH change was
improved by using a two dye-doped sol-gel coating film.
Numerical Study of the Magnetic Effect on the Compressive Air Flow at an Intake
Authors: I. Wakayama Masako Iwata
Published: October 2002

Air flows under a magnetic field at an intake are examined by means of numerical simulation.
The air flow is caused by the pressure difference and the flow rate is measured to determine the effect of the magnetic field at the intake.
The flow is assumed to be compressible and inviscid.
Under the magnetic field, the air flow rate at the intake is more than double that without the magnetic field after having reached steady flow.
Even in the inviscid flow, vortices are generated under the magnetic field and after their movement the air flow increased markedly.
Magnetic Acceleration of Inhaled and Exhaled Flows in Breathing
Authors: Wakayama Nobuko I. , Wakayama Mariko
Published: October 2002

Time dependence of the velocity of inhalation and exhalation in
breathing was measured in the presence and absence of a magnetic
field. When a U-shaped permanent magnet of central magnetic strength
0.7 T was set around the location of air intake, the average
velocity of inhaled and exhaled flows increased by about 23%. When
a permanent magnet was brought in contact with the nose and a
magnetic field was applied inside a nostril, the average velocity
increased by about 18%. Magnetic acceleration was efficient when
air flowed into a narrower space in the direction of increasing
magnetic field strength. The present study suggests a novel method
which assists breathing.
Field Emission Patterns Originating from Pentagons at the Tip of a Carbon Nanotube
Authors: Saito Yahachi , Hata Koichi , Murata Tsunetaka
Published: October 2002

Field emission of electrons from multiwall carbon nanotubes (MWCNTs) has been
investigated in ultra-high vacuum by field emission microscopy (FEM). MWCNTs whose
tips are capped by curved graphite layers give FEM patterns consisting of 6 bright
pentagons, each of which has a dark region in its center. Interference fringes are also
observed between adjacent pentagonal rings. The present result shows a direct
evidence of the presence of 6 pentagons on a tip of a closed carbon nanotube.
Composition and Surface Structure of Quantum Chains on a In/Si(111) Surface
Authors: A. Saranin Alexander , G. Lifshits Victor , Mitsuhiro Katayama Mitsuhiro Katayama , Kenjiro Oura Kenjiro Oura
Published: October 2002

Using scanning tunneling microscopy, the composition of
the Si(111)4×1-In surface was determined.
It was found that the
4×1 (8×2)-In reconstruction
has an In coverage of 3/4 monolayers (ML) and a top layer
Si atom density of 1/2 ML.
A possible
structural model of the low-temperature 8×2-In reconstruction,
which adopts the obtained composition and explains the
recently observed 4×1 ↔8×2 transition
is proposed.
Chemical Structure of Aluminum/8-Hydroxyquinoline Aluminum Interface
Authors: Isomura Noritake , Mitsuoka Takuya , Ohwaki Takeshi , Taga Yasunori
Published: October 2002

The chemical structure of interfaces between aluminum (Al) and
8-hydroxyquinoline aluminum (Alq3) has been studied by X-ray photoelectron
spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS).
New subpeaks of N1s and O1s in XPS spectra were observed
after the deposition of Al on Alq3. The secondary ion intensity of quinoline in
TOF-SIMS spectra was found to increase with Al coverage on Alq3. We, therefore,
conclude that Alq3 is decomposed by the deposition of Al on Alq3, and that
quinoline is formed at the Al/Alq3 interface.
Containerless Melting of Glass by Magnetic Levitation Method
Authors: Kitamura Naoyuki , Makihara Masaki , Hamai Miho , Sato Takayuki , Mogi Iwao , Awaji Satoshi , Watanabe Kazuo , Motokawa Mitsuhiro
Published: October 2002

The Melting of glass materials levitated in high magnetic fields has been carried
out without a crucible by using a hybrid magnet and a CO2 laser. A cubic glass with
6 mm sides has become a complete sphere through melting and cooling in the air. This
new method will provide opportunities for obtaining high-purity and new heterogeneous
materials.
Improvement of Crystal Quality of RF-Plasma-Assisted Molecular Beam Epitaxy Grown Ga-Polarity GaN by High-Temperature Grown AlN Multiple Intermediate Layers
Authors: Kikuchi Akihiko , Yamada Takayuki , Nakamura Shinichi , Kusakabe Kazuhide , Sugihara Daisuke , Kishino Katsumi
Published: October 2002

The effects of high-temperature-grown AlN multiple intermediate layers
(HT-AlN-MILs) on the crystal quality of Ga-polarity GaN layers grown on (0001)
Al2O3 substrates by molecular beam epitaxy using rf-plasma nitrogen source
were investigated. The high-temperature-grown AlN intermediate layers (HT-AlN-ILs)
with different thicknesses were found to play different roles in the improvement of
crystal quality. The 8-nm-thick HT-AlN-ILs brought about improvement of electrical
properties. On the other hand, the 2-nm-thick HT-AlN-ILs improved the surface
morphology. The combination of these 8-nm-HT-AlN-ILs and 2-nm-HT-AlN-ILs improved
both the electrical properties and the surface morphology concurrently.
Effects of Atomic Hydrogen on the Indium Incorporation in InGaN Grown by RF-Molecular Beam Epitaxy
Authors: Yoshihiro Okamoto Yoshihiro Okamoto , Kazuya Takahashi Kazuya Takahashi , Hiromichi Nakamura Hiromichi Nakamura , Yoshitaka Okada Yoshitaka Okada , Mitsuo Kawabe Mitsuo Kawabe
Published: October 2002

We investigated the effect of atomic hydrogen(H) irradiation on the In incorporation
in InGaN films grown by RF-molecular beam epitaxy (MBE).
The molecular hydrogen (H2) and atomic H irradiation in InGaN growth by RF-MBE
were found to enhance the In incorporation.
The atomic H irradiation in InGaN growth increased the In incorporation
with increasing H2 flow rate.
The In incorporation for samples grown with H was higher than without H2
in the temperature range of 640°C to 700°C.
These results may represent a new and interesting avenue of investigation
into the understanding of growth of III-nitride films.
We consider that the mechanisms responsible for the modification of
In incorporation by atomic H irradiation are mainly
due to an increase of the nitrogen species
and partly to suppression of 3-dimensional(3-D) growth
thereby enhancing a 2-D growth.
Photoinduced Highly Efficient Second-Harmonic Generation in Azo-Dye-Doped Thick Films
Authors: Kitaoka Kenji , Si Jinhai , Mitsuyu Tsuneo , Hirao Kazuyuki
Published: October 2002

4-[N-ethyl-N-(2-hydroxyethyl)]amino-4'-nitro-azobenzene (DR1)-doped
poly(methyl methacrylate) (PMMA) thick films were optically polarized by the coherent
superposition of the 1500-nm fundamental and the 750-nm second-harmonic lights of
a 130-fs pulse laser. These films were successfully polarized despite the transparent
seed beams' wavelength for the dye, and the second-harmonic generation (SHG)
conversion efficiency of a 96-µm-thick film was estimated to be 1.6% at the
pump beam power of 11.1 GW·cm-2. The relaxation was found to be
suppressed with increasing film thickness.
Efficient Terahertz Radiation Generation from a Bulk InAs Mirror as an Intracavity Terahertz Radiation Emitter
Authors: Liu Zhenlin , Ono Shingo , Ohtake Hideyuki , Sarukura Nobuhiko , Liu Tze-An , Huang Kai-Fung , Pan Ci-Ling
Published: October 2002

Terahertz (THz) radiation is generated efficiently from a bulk InAs mirror with
a shallow incidence angle inside the cavity of a femtosecond, mode-locked Ti:sapphire
laser self-started by a strained saturable Bragg reflector. A magnetic field is also
applied to the InAs mirror to enhance THz radiation.
Compositional Dependence of Electrical Characteristics in SrBi2Ta2-xNbxO9 Ferroelectric Capacitor Reduced by H2 Annealing
Authors: D. Cuchiaro Akira Furuya
Published: October 2002

Degradation of electrical properties by annealing in hydrogen ambient is one of
the most significant problems associated with ferroelectric oxides used in
mainstream nonvolatile memory. A decrease in the degradation of the remanent
polarization and the breakdown voltage of a ferroelectric
SrBi2Ta2-x
Nb
x
O9 (SBTN) capacitor has been attempted by
controlling the Ta/Nb ratio, adding excess Bi oxide and adding excess Nb
oxide. Substituting Nb for Ta improves the remanent polarization, however, it
also leads to a decrease in the breakdown voltage.
Excess Bi and Nb oxide both decrease the remanent polarization. Regarding the
breakdown voltage, the addition of excess Bi and Nb oxide decrease the amount
of the degradation caused by short-time H2-annealing, although it
is not enough to prevent the degradation caused by long-time H2
annealing. Furthermore, the reduction path in the ferroelectric capacitor by
low-temperature H2 annealing is discussed.
P-Type GaN Formation by Mg Diffusion
Authors: Yang Ying-Jay , Yen Jia-Liang , Yang Fuh-Shyang , Lin Ching-Yen
Published: October 2002

Magnesium (Mg) diffusion into unintentionally doped n-type GaN to form p-type GaN was
studied. The Hall measurement data indicated that the diffused and annealed samples consistently
show p-type conductivity with average hole concentrations in the range of 1016 cm-3–1017 cm-3 and
mobility of <90 cm2·V·s. The diffused GaN showed a strong
Mg related emission band with zero
phonon peak at 3.27 eV and followed by two longitudinal optical (LO) phonon replica with ∼90 meV separation at 10 K.