bluuebunny/crossref_metadata_2025 huggingface dataset:
Change of Macroscopic and Microscopic Symmetry of Barium Titanate Single Crystal around Curie Temperature
Authors: Wada Satoshi , Suzuki Takeyuki , Osada Minoru , Kakihana Masato , Noma Tatsuo
Published: October 2002

Using a high-quality barium titanate single crystal grown by a top-seeded solution
growth method, its microscopic and macroscopic symmetries were investigated by Raman
scattering measurement and polarizing microscopy, respectively. Moreover, their
temperature dependences through Curie temperature were also studied. As a result, we found
that the microscopic symmetry of P4mm observed at room temperature did not change
through Curie temperature. On the other hand, the macroscopic symmetry on the basis of a
insitu domain observation was P4mm below 133°C and Pm3m above the Curie temperature.
This difference between microscopic and macroscopic symmetries above the Curie
temperature suggests that the barium titanate single crystal above the Curie temperature
intrinsically exhibits some disorder behavior. On the basis of the results obtained in this
study, the phase transition model of barium titanate single crystal with both displacive and
order-disorder behaviors was proposed.
Raman Scattering in Relaxor Pb(Zn1/3Nb2/3)O3
Authors: Ohwa Hidehiro , Iwata Makoto , Yasuda Naohiko , Ishibashi Yoshihiro
Published: October 2002

The Raman spectra of relaxor ferroelectrics in the single crystal Pb(Zn1/3Nb2/3)O3
(PZN) have been measured with the 90°scattering geometry over a wide temperature
range between 100 K and 773 K and over a frequency range up to 1000 cm-1. The
Raman-active modes exist well above the diffuse transition temperature of about 413 K
(the cubic phase) implying that the space group of the cubic phase in PZN is not Pm3m.
It is found that far above room temperature, the Raman spectra in the X(Z
Z)Y and
X(Z
X)Y geometries are different, whereas below room temperature they are almost the
same.
Optoelectronic and Structural Properties of Good Quality Hydrogenated Amorphous Silicon Carbide Films Deposited by Hot Wire Assisted RF Plasma Deposition Technique
Authors: Chattopadhyay S. , Das Debabrata , Barua A. K. , Williamson D. L. , Kshirsagar S. T.
Published: October 2002

Hydrogenated amorphous silicon carbide (a-SiC:H) films were
deposited by using a combination of radio frequency plasma enhanced
chemical vapour deposition (RF-PECVD) and heated filament techniques
with the objective of improving the quality of the films due to the
possible beneficial effect of the latter technique. The atomic hydrogen
produced via electron (emitted from the filament) impact dissociation
of the process gases plays a significant role in improving the
properties of the film such as the structure and bonding configuration.
The electrons emitted from the hot filament also help in dissociation
of methane molecules into different types of radicals. From the
characterization of the films thus produced it is seen that by the
combination of the two methods of deposition under optimised condition
carbon is incorporated more as a Si–C bond which is structurally better.
These results in better opto-electronic properties at high band gap of
a-SiC:H which also shows lower light induced degradation than those of
the films produced by only using the RF PECVD method.
Ultrafast Relaxation of Photoexcited Carriers in Semiconductor Superlattices
Authors: Je Koo-Chul , Kim Yup
Published: October 2002

The differential transmission signal (DTS) of a pump-probe
transmission experiment on the GaAs/AlGaAs superlattice
is calculated using the effective semiconductor Bloch equation and
by assuming that the main mechanism of the relaxation for a low carrier density
is the carrier LO-phonon scattering. From the theoretical
analysis of the DTS signal, the intrasubband and intersubband
relaxation times of the carriers which are excited optically
to the second miniband are estimated.
The results are compared to those of
recent femtosecond pump-probe experiments
on the GaAs/AlGaAs superlattice.
Alternative Interpretation of Impulse Response of Phonon-Polaritons
Authors: Kawashima Hitoshi , Sasaki Fumio , Kobayashi Shunsuke , Tani Toshiro
Published: October 2002

A new technique to deal with the time-resolved data, without referring to a dispersion
relation, is proposed for an optical grating experiment on an electrooptic medium. The
fundamental concept behind this approach is a simple relation among macroscopic and
measurable quantities. General features concerning the behavior of the observable are
formulated, some of which have been overlooked in the past studies. The most important
characteristic is that the index changes measured at three different spatial frequencies are
sufficicient for determining the dielectric and electrooptic properties of the medium. Possible
approximations in the present approach are discussed in connection with the results of the
previous time-resolved studies on LiTaO3.
Determination of Dielectric Relaxation Time of Langmuir-Films by a Whole-Curve Method Using the Maxwell Displacement Current
Authors: Sato Yoko , Wu Chen-Xu , Majima Yutaka , Iwamoto Mitsumasa
Published: October 2002

A whole-curve method using the Maxwell displacement current (MDC) is presented for determining the dielectric relaxation time τ of floating monolayers on the water surface. The dielectric relaxation time of 4-cyano-4'-alkyl-biphenyle (5CB) monolayers was examined. It was revealed that the dielectric relaxation time τ of 5CB monolayers depends on the molecular area, and shows a good agreement with the theoretical relaxation time in the isotropic polar orientational phase, which was calculated using a rodlike columnar molecule model.
An Ultrasonic Motor Using a Metal-Ceramic Composite Actuator Generating Torsional Displacement
Authors: Koc Burhanettin , Dogan Aydin , Xu Yuan , Newnham Robert E. , Uchino Kenji
Published: October 2002

An ultrasonic motor composed of three components; a stator, a rotor and a
ball bearing is proposed. The stator is made of an active piezoelectric
ring, poled in the thickness direction and bonded with two windmill-like
slotted metal endcaps. The stator is excited through its two electrodes,
generating ultrasonic vibration in the radial direction at a radial mode
resonance frequency. The two identical metal endcaps on both sides of the
ring, bonded after shifting 45° with each others, transfers the radial
vibration into longitudinal and tangential vibrations. The combination of
these vibrations (longitudinal and tangential) generates rotation due to
frictional interaction between the center part of the top endcap and the
periphery of the rotor. A prototype motor with 11.0 mm diameter was
fabricated and its transient characteristics were measured. The maximum
torque of 1.36 mNm was obtained at a speed of 480 rpm.
Positive Ions in RF Discharge Plasmas of C4F8/Ar and C4F8/O2 Mixtures
Authors: Yuji Hirose Yuji Hirose , Itsuo Ishikawa Itsuo Ishikawa , Shinya Sasaki Shinya Sasaki , Kazuya Nagaseki Kazuya Nagaseki , Yukinori Saito Yukinori Saito , Shinji Suganomata Shinji Suganomata
Published: October 2002

Discharge plasmas of C4F8/Ar and C4F8/O2 mixtures were investigated at a frequency of 13.56 MHz and a power of 34 W and at a pressure of 50 mTorr. Discharge-sustaining voltages vary almost monotonically with the gas mixing ratio. The major positive ions in C4F8/Ar discharge are C2F4
+, CF3
+ and Ar+. The ion count ratio of CF+ is the most intense among the positive ions in the CF system at a large Ar mixing ratio. From the variations of the ion count ratio of CF
x

+ (x=0–3), these ions seem to be produced partly by the electron-impact ionization of radicals generated from fluorocarbon films. In C4F8/O2 discharge, the major positive ions are C2F4
+, CF3
+, CO+ and O2
+. The intensity ratios of ionic species vary as a function of gas mixing ratio. The ion count ratio of CO+, COF+ and COF2
+ reach a maximum at an O2 mixing ratio of about 50%, and the ion count ratio of CO+ is much higher than that of O2
+. This seems to suggest some secondary collision processes that occur in the discharge plasma.
Microwave Plasma in a Multicusp Circular Waveguide with a Dimension below Cutoff
Authors: Sudeep Bhattacharjee Sudeep Bhattacharjee , Hiroshi Amemiya Hiroshi Amemiya
Published: October 2002

A microwave plasma is produced in a nearly circular multicusp
waveguide with a cross section smaller than the cutoff value. Permanent magnets are used to form the
multicusp. Plasma density above the cutoff value was obtained in the range of 10-4 Torr at a power
density of 6 – 10 W/cm2 for 2.45 GHz. The plasma production in the narrow waveguide and its
characteristics are discussed.
Velocity Distribution Measurements of a Supersonic Methane Molecular Beam Reflected from a Pt(111) Surface at Various Reflection Angles
Authors: Yagyu Shinjiro , Kita Hisae , Kino Yasunobu , Ozeki Kouta , Sasaki Masahiro , Yamamoto Shigehiko
Published: October 2002

Velocity distribution measurements of a supersonic molecular beam of methane molecules
reflected from a Pt(111) surface have been made and results are analyzed based on the classical
collision model, the hard cube model [J. Chem. Phys. 44 (1966) 195]. The “drift speed” and
“beam temperature”, deduced by fitting the obtained distributions with the model calculations,
vary with the angle of reflection as predicted by the model. Disagreements are supposed to arise
from the simplicity of the model such as neglect of surface potential roughness and the
dispersive forces acting between the methane molecules and the surface atoms. Excitation of
internal modes of methane molecules during the collision at the surface is considered possible.
Noncontact Measurement of Doping Profile for Bare Silicon
Authors: Kohno Motohiro , Matsubara Hideaki , Okada Hiroshi , Hirae Sadao , Sakai Takamasa
Published: October 2002

In this study, we evaluate the doping concentrations of bare silicon
wafers by noncontact capacitance–voltage (C–V) measurements. The metal-air-insulator-semiconductor (MAIS) method enables the measurement of C–V
characteristics of silicon wafers without oxidation and electrode preparation.
This method has the advantage that a doping profile close to the wafer surface
can be obtained. In our experiment, epitaxial silicon wafers were used to
compare the MAIS method with the conventional MIS method. The
experimental results obtained from the two methods showed good agreement.
Then, doping profiles of boron-doped Czochralski (CZ) wafers were measured
by the MAIS method. The result indicated a significant reduction of the doping
concentration near the wafer surface. This observation is attributed to the
well-known deactivation of boron with atomic hydrogen which permeated the
silicon bulk during the polishing process. This deactivation was recovered by
annealing in air at 180°C for 120 min.
Solution of the Knapsack Problem by Deoxyribonucleic Acid Computing
Authors: Yohei Aoi Yohei Aoi , Tatsuo Yoshinobu Tatsuo Yoshinobu , Katsuyuki Tanizawa Katsuyuki Tanizawa , Kozo Kinoshita Kozo Kinoshita , Hiroshi Iwasaki Hiroshi Iwasaki
Published: October 2002

Deoxyribonucleic acid (DNA) computing is executed to demonstrate that it is capable
of solving a simple instance of the knapsack problem, which is known to be NP-complete.
DNA molecules with different lengths coding the data are prepared, and the algorithm is
implemented as molecular biological processes such as ligation, polymerase chain reaction
(PCR), and DNA sequencing. The scheme of encoding, experimental procedures and results
are described, and the scalability of the present method is discussed. Reactions between DNA
molecules are expected to realize a massively parallel computation of the order of 1023 per
mol.
Mechanism of Improved Thermal Stability of Cobalt Silicide Formed on Polysilicon Gate by Nitrogen Implantation
Authors: Sun Wein-Town , Lee Hai-Ming , Liaw Ming-Chi , Hsu Charles Ching-Hsiang
Published: October 2002

It is found that the thermal stability of CoSi2 films is improved by N2
+ implantation (I/I) because
the grain size of CoSi2 films with N2
+ I/I is much smaller than that without N2
+ I/I. Rutherford
backscattering spectrometry (RBS) and Auger electron spectroscopy (AES) analyses show that the
nucleation of CoSi2 transformation from CoSi is suppressed by N2
+ I/I. The nucleation
temperature for the sample with 5×1015 cm-2 N2
+ I/I is about 25°C higher than that without N2
+ I/I. Since the
nucleation temperature is increased, CoSi2 films are formed incompletely at the as-formed state; thus,
CoSi2 has small grain size. As a result, the thermal stability of CoSi2 films is significantly improved
by N2
+ I/I due to the small grain size of CoSi2.
Transient Enhanced Diffusion of Boron in the Presence of Dislocations Produced by Amorphizing Implantation in Silicon
Authors: Uematsu Masashi
Published: October 2002

We have simulated transient enhanced diffusion (TED) of boron in the
presence of dislocations produced by amorphizing implantation. A unified
simulation was done, taking into account that end-of-range (EOR)
dislocations act as both a sink for and source of self-interstitials, depending
on temperature and annealing time. We have simulated B TED profiles both
in regrown regions and beneath EOR dislocations produced by Si
implantation at room temperature. Simulation results indicate that EOR
dislocations do not act as a perfect barrier to self-interstitial diffusion. In
addition, the simulation well reproduces the experimental profiles by taking
into account another type of defect that maintain self-interstitial
concentration at thermal equilibrium values in the regrown region.
300-kilo-Gate Sea-of-Gate Type Gate Arrays Fabricated Using 0.25-µm-Gate Ultra-Thin-Film Fully-Depleted Complementary Metal-Oxide-Semiconductor Separation by IMplanted OXygen (CMOS/SIMOX) Technology with Tungsten-Covered Source and Drain
Authors: Sato Yasuhiro , Kado Yuichi , Tsuchiya Toshiaki , Kosugi Toshihiko , Ishii Hiromu
Published: October 2002

A 120-kilo-gate (KG) fully functional gate-array LSI consisting of basic cells with a single-contact
layout (single-contact cells) is fabricated on 300-KG sea-of-gate (SOG) type gate arrays
using 0.25-µm ultra-thin-film fully-depleted (FD) complementary metal-oxide-semiconductor separation by implanted oxygen (CMOS/SIMOX) technology with selective W
chemical vapor deposition (CVD). This paper shows that the performance of circuits made with
single-contact cells can be as high as that with multi-contact cells, when the source/drain sheet
resistance is below 5 Ω/sq. It also shows that selective W-CVD with the hydrogenation-and-hydrogen-termination
(HHT) treatment can provide this sheet resistance even in ultra-thin-film
silicon-on-insulator (SOI) substrates with a 50-nm-thick silicon layer. Single-contact cells built with
selective W-CVD were applied to metal-oxide-semiconductor field effect transistors (MOSFETs), 2-input NAND circuits, and gate-array LSIs.
Consequently, these cells did not degrade the drain current of transistors, or raise the gate delay time
of the circuits. Single-contact cells built with W did not lower the yield of LSIs up to 120 KG
compared to LSIs made with multi-contact cells without W. Furthermore, the 120-KG LSI
consisting of single contact cells with W had no decrease in speed, compared to one with multi-contact
cells. These results indicate that the selective W-CVD is a promising technology to increase
the packing density of LSIs made with ultra-thin-film FD CMOS/SOI.
Three-dimensional Calculation of Residual Stress in InP Layers Grown by Microchannel Epitaxy on Si Substrates
Authors: Shigeya Naritsuka Shigeya Naritsuka , Ibuki Handa Ibuki Handa , Tatau Nishinaga Tatau Nishinaga
Published: October 2002

The residual stress in InP layers grown by microchannel epitaxy (MCE) on Si substrates was calculated using the three-dimensional finite element method (FEM). In the calculation, stress is assumed to be produced by the difference in thermal expansion between InP and Si during the cooling stage after the growth. No formation or movement of dislocations, by which the stress is released, is assumed. The calculation shows that the island structures of MCE layers are useful to reduce thermally induced stress. For example, stress in an MCE layer can be reduced to one-hundredth of that of a conventional uniform epitaxial layer. The calculation also shows that the stress at the MCE surface decreases rapidly with increasing the layer thickness. On the other hand, the change in stress is very small with varying the line-seed width or the thickness of the SiO2 mask. It is shown that the residual stress is further decreased when the MCE layer slips freely on the SiO2 mask.
Top-Gate Staggered Amorphous Silicon Thin-Film Transistors: Series Resistance and Nitride Thickness Effects
Authors: Chiang Chun-sung , Martin Sandrine , Kanicki Jerzy , Ugai Yasuhiro , Yukawa Teizo , Takeuchi Shu
Published: October 2002

Top-gate staggered hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) were
fabricated over large-area glass substrates using a selective phosphorus-treatment (PT) of indium-tin-oxide (ITO) source/drain electrodes. The ohmic contact between a-Si:H and ITO had a
specific contact resistivity of about 0.18 Ω·cm2. For a 100-µm channel length TFT, the
source/drain series resistance contributes less than 5% of the total drain-to-source resistance. This
contribution increases to about 25% for a 10-µm channel length TFT. Our study also indicated
that the interface quality of a-Si:H/a-SiN
x
:H is amorphous silicon nitride (a-SiN
x
:H) and a-Si:H
thickness independent and dependent, respectively. Effective interface state densities of about 1.5×1012 cm-2eV-1 and 3.2×1012 cm-2eV-1 were obtained for top-gate TFTs with a 1300 and
300 Å thick a-Si:H films, respectively. Channel conductance activation energy of about
0.1 eV was measured for this top-gate TFT with 300 Å a-Si:H.
Interfacial Layer in Thermally-grown Ultra thin Silicon Dioxides Measured by Grazing Incidence X-Ray Reflection
Authors: Matsumura Mieko , Sakoda Tomoyuki , Nishioka Yasushiro
Published: October 2002

The effects of oxidation temperature and post-oxidation annealing (POA) on density variation within
ultra-thin (3 nm) silicon dioxide films were investigated via grazing incidence X-ray reflection
(GIXR). At the SiO2/Si interface, it was found that the oxide films without POA have slightly denser
layers than those of the bulk. These interfacial layers were found to be thicker for the oxide grown at a
lower temperature and to become indistinguishable from the bulk of the film after POA.
Effects of Delay Lines on Surface Acoustic Wave Resonator Filters and Their Applications
Authors: Chu Sheng-Yuan , Water Walter
Published: October 2002

The surface acoustic wave (SAW) resonator filters consisting of a pair of
interdigital-electrode transducers can generate and transmit acoustic waves. By
inserting a grating, we can improve the frequency response and lower the insertion loss;
therefore appropriate design of the delay line will be very important. In this paper, we
used the coupling-of-mode (COM) theory to model the frequency response of the SAW
device and discuss the influence of the delay line on the frequency response. We found
that the optimum delay line distance and the corresponding insertion loss is very small,
which will be very helpful in designing corresponding SAW-coupled resonator filters.
Evaluation of Hole Traps in 10-MeV Proton-Irradiated p-Type Silicon from Hall-Effect Measurements
Authors: Hideharu Matsuura Hideharu Matsuura , Yoshitsugu Uchida Yoshitsugu Uchida , Tadashi Hisamatsu Tadashi Hisamatsu , Sumio Matsuda Sumio Matsuda
Published: October 2002

Using the temperature dependence of the hole concentration p(T) obtained from Hall-effect measurements, we attempt to uniquely determine the densities and energy levels of hole traps in 10-MeV proton-irradiated p-type silicon.
Since the function p(T) exp
(E
ref/k
T)/k
T has a peak at the temperature corresponding to each hole trap level, the trap densities and energy levels can be determined uniquely and accurately.
Here, k is the Boltzmann's constant, T is the absolute temperature and E
ref is a newly introduced parameter which shifts the peak temperature of the function within the measurement temperature range.
Three types of hole trap levels (about 0.09 eV, 0.13 eV and 0.19 eV above the top (E
V) of the valence band) are observed, and these hole trap densities increase with increasing 10-MeV-proton fluence.
The hole traps at E
V + 0.09 eV and E
V + 0.19 eV have been reported and their origins have been discussed.
However, the hole trap at E
V + 0.13 eV has not yet been reported.
The quantitative relationship between the decrease in hole concentration and the increase in densities of certain traps due to proton irradiation has been clarified for the first time.
Effect of Glass Addition on Microwave Properties of BaO·La2O3·4.7TiO2
Authors: Lee Cheng Chung , Lin Pang
Published: October 2002

The effects of the addition of glass to the microwave properties of
BaO·La2O3·4.7TiO2 ceramics were investigated. Three commercial glasses:
PbO–B2O3–SiO2 (GA9), ZnO–B2O3–SiO2 (GP032) and PbO–B2O3 (LS3081),
were investigated in this study. The ceramics without glass addition and
sintered at 1300°C gave the relative dielectric constant ε
r=92, quality factor
Q=1653 and temperature coefficient of resonant frequency τf=40.3 ppm/°C at
3.0 GHz. With 20 wt% GA9 addition, highly dense samples (void fraction were
≤2.5 vol%) were obtained at T
s≥900°C and their microwave properties were:
ε
r≥64, Q≥1037 and τf≤15.3 ppm/°C at 3.0 GHz. The high sintering temperature
increased ε
r and Q values but decreased the value of τf. The densification of
specimens was found to play an important role in improving the dielectric
constant. Heterogeneous interfaces and the dissolution of trace amounts of
ceramics in glass increased the dielectric loss significantly; also, the former
increased τf whereas the latter decreased it.
Ferro/Antiferroelectricity and Phase Relations of Pb(Yb1/2Nb1/2)O3–PbZrO3 Solid Solution on PbZrO3-Rich Side
Authors: Yokosuka Masaru
Published: October 2002

In order to examine how the intermediate ferroelectric phase inherent to
pure PbZrO3 changes when PbZrO3 is partially replaced by the
antiferroelectric Pb(Yb1/2Nb1/2)O3, dielectric constants, D–E hysteresis loops
and a linear thermal expansion were measured as functions of both
temperature and composition. In particular, regarding the successive phase
transitions, paraelectric through ferroelectric to antiferroelectric, a thermal
elongation was analyzed on the basis of the phenomenological theory
presented by Uchino et al.. [Jpn. J. Appl. Phys. 19 (1980) L425]. When
PbZrO3 was replaced by Pb(Yb1/2Nb1/2)O3 within the amount of 2.5–15 mole%, the intermediate ferroelectric phase was shown to disappear.
Finally, the phase relations of the solid solution Pb(Yb1/2Nb1/2)O3–PbZrO3 on
the PbZrO3-rich side were clarified.
Simulation of the Voltage Holding Ratio in Liquid Crystal Displays with a Constant Charge Model
Authors: Sasaki Nobuyoshi
Published: October 2002

A model for simulating the voltage holding ratio in liquid
crystal (LC) cells and investigating the influence of ionic
impurities on device performance is proposed. Active matrix
addressed liquid crystal displays (AM-LCDs) are composed of
insulator materials between two electrodes, and are driven by
pulse-voltage application. In this model, the charge density
accumulated on an electrode is assumed to be constant in the
open-circuit state. The voltage decay is described as a change in
the internal electric field induced by ion polarization and the
increased capacitance caused by LC reorientation. Results
calculated using this model qualitatively reproduced measured
voltage decays.
Dielectric Properties in Ferroelectric Liquid Crystal Mixtures with Ultrashort Pitch
Authors: Zennyoji Masahito , Yokoyama Jun , Takanishi Yoichi , Ishikawa Ken , Takezoe Hideo , Itoh Keizo
Published: October 2002

The dielectric propereties of smectic liquid crystal mixtures
containing chiral dopants derived from trifluoromethylated
pyranose were studied. In every mixture, a large dielectric
response due to the Goldstone mode was observed, indicating the
smectic C* phase, although two switching current peaks
indicative of the smectic CA
* phase were observed in the
mixtures with high dopant ratios. With increasing the chiral
dopant ratio, the dielectric strength becomes smaller and the
relaxation frequency becomes larger. This behavior was
qualitatively explained by the chiral dopant ratio dependence of
the spontaneous polarization and the helicoidal pitch. It was also
found that a higher dc bias field was required to suppress the
Goldstone mode in the mixture with a higher dopant ratio,
suggesting the helicoid-stabilized state.
Scanning Tunneling Microscopy Study of the Misfit Layer Compounds (LaSe)xNbSe2 and (PbSe)xNbSe2
Authors: Contera Sonia Antoranz , Tatsuo Yoshinobu Tatsuo Yoshinobu , Hiroshi Iwasaki Hiroshi Iwasaki , Kenji Kisoda Kenji Kisoda
Published: October 2002

Atomic images of the misfit layer compounds (LaSe)xNbSe2 and
(PbSe)xNbSe2 were obtained with a scanning tunneling microscope
(STM) operating in constant height mode in air. It was possible to record
pictures of only the NbSe2 layers of both compounds, the LaSe and PbSe
layers could not be observed. Formation of stage-2 portions embedded in the
stage-1 crystal and instability of the LaSe and PbSe layers under the scanning
conditions are discussed as possible causes. Comparing with the NbSe2 crystal,
the lattice of the NbSe2 layers of the misfit layer compounds
appear deformed. Nonperiodic Moiré-like structures have been observed in the
(LaSe)xNbSe2 surface. We consider that this feature is caused by the
STM tip pushing down the surface where it is softer. The nonperiodicity of the
patterns might be due to the strain conditions of the crystal growth that would
give rise to dislocations and defects.
Optical Properties of Aluminumquinoline-Oxadiazole Codeposited Luminescent Layers
Authors: Mitsuru Asano Mitsuru Asano , Tadahiro Nakazawa Tadahiro Nakazawa , Kentaro Ueda Kentaro Ueda , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: October 2002

Aluminumquinoline-oxadiazole (Alq3-PBD) codeposited layers,
where the heterojunction of Alq3 and PBD is expected to possess
type-I energy lineup,
were fabricated by vacuum evaporation,
and their optical properties were investigated.
The results showed effective energy transfer from PBD to Alq3
followed by dominant emission from Alq3,
even at the Alq3 concentration as low as about 1.5%.
By using the Alq3-PBD codeposited layer
as the emitting layer of electroluminescence (EL) devices,
a successful increase in output power and quantum efficiency
was observed compared to conventional EL structures.
Dispersion-Compensation Electron-Energy-Loss Spectrometer
Authors: andYukihiro Taguchi Hiroshi Okuyama
Published: October 2002

A dispersion-compensation electron-energy-loss spectrometer
which consists of two 90° spherical sectors has been constructed
and its characteristics have been tested.
We have obtained the detector current of 160 pA
with the full-width at half maximum of 25 meV
for the primary electron energy of 19.5 eV in the direct mode,
where electrons passing through the monochromator
are directly detected by the analyzer without reflection from a sample.
The obtained characteristics have been discussed,
and suggestions for the design of an advanced spectrometer have been given.
Dose Dependence of the Enhancement of Thermal Oxidation for 6H-SiC by 30 keV 18O+ and 20Ne+ Irradiation
Authors: Yoneda Tomoaki , Nakata Toshitake , Kitabatake Makoto , Kido Yoshiaki
Published: October 2002

The oxidation rate of the Si-face of 6H-SiC was significantly enhanced by 30 keV 18O+ and 20Ne+ irradiation at high doses followed by thermal annealing at 1100°C in a wet oxygen atmosphere. This oxidation rate strongly depends on the ion dose. We found three regions of oxidation rate dependence on the ion dose. The three regions show the same low oxidation rate as that of the standard SiC, an oxidation rate with increased values and an oxidation rate with the fastest and saturated value. The dose dependences of the total damage obtained from Ruterford backscattering spectroscopy (RBS) measurements and of the oxide thickness are different. However, the dose dependence of the spin density determined from electron spin resonance (ESR) measurements corresponded to. The high density of dangling bonds in SiC induced by ion irradiation is considered to result in the increase of the diffusion coefficients for oxygen in SiC. Therefore, the oxidation rate of SiC is significantly enhanced. The enhanced oxidation was found to be related to the quality of the damaged layer and required higher dose than the dose necessary for amorphization, which was determined from RBS and ESR measurements.
Electron Spin Resonance Study of Light-Induced Annealing of Dangling Bonds in Glow Discharge Hydrogenated Amorphous Silicon: Deconvolution of Electron Spin Resonance Spectra
Authors: Takeda Kosei , Hikita Harumi , Kimura Yutaka , Yokomichi Haruo , Morigaki Kazuo
Published: October 2002

We analyze the electron spin resonance (ESR) spectra of dangling
bonds in a-Si:H samples before and after strong illumination which gives
rise to the phenomenon of light-induced annealing of dangling bonds. The
spectra are deconvoluted into two components, that due to normal dangling
bonds and that due to H-related dangling bonds. Both before and after
prolonged illumination, the normal dangling bonds constitute about 60%
of the total spin density, while the H-related dangling bonds constitute about
40%. However, the photoannealed densities of the two types of dangling
bonds are found to be different after strong illumination. In addition, we
analyze the ESR spectra of dangling bonds observed after weak
illumination.
Fit of Temperature Dependence of Semiconductor Band Gaps
Authors: Chiu Kuan-Cheng , Su Yu-Ching , Tu Hang-An
Published: October 2002

A numerical fit for the temperature dependence of semiconductor band gaps
of the form E
g(T)=E
g(0)-S<\hbarΩ>[coth
(<\hbarΩ>/2k
B
T)-1] is applied to several important elemental and III–V compound
semiconductors. From a systematic analysis, the relation between <\hbarΩ> and Debye temperature is derived, and a new effective coupling constant is defined to demonstrate the relative strength of the electron-phonon interaction on the semiconductor band-gap energy.
Comparison of the In-Plane Magnetic Anisotropy Dispersion Obtained Using Transverse Biased Initial Susceptibility Technique Performed by Magnetooptical Kerr Effect and Ferromagnetic Resonance Technique: The Role of the Large Angle Ripple
Authors: Calleja Javier F. , Gutiérrez Manuel O. , Suran Gabor , Corrales Jose A. , Contreras Carmen
Published: October 2002

The in-plane magnetic anisotropy and its dispersion in rf-sputtered (Co93Zr7)100-x
RE
x
thin
films (RE=Pr, Nd and Tb; x < 3.5) were investigated by two different techniques: transverse biased initial susceptibility technique where measurements are performed based
on the magnetooptical Kerr effect and by ferromagnetic resonance technique. The films
exhibit a very well-defined in-plane magnetic anisotropy with negligible long-range
fluctuations of the anisotropy along the easy axis, so the anisotropy dispersion is discussed
in terms of the ripple, which is related to the magnetic local anisotropy. The anisotropy
dispersion values obtained by both techniques are compared, which allow us to determine
the role of the large angle ripple in the anisotropy dispersion and its relationship with local
anisotropy. We also analyze the advantages and disadvantages of each
technique.
Deep-Submicron Lightly-Doped-Drain and Single-Drain Metal-Oxide-Semiconductor Transistor Drain Current Model for Circuit Simulation
Authors: Liu Shau-Shen , Jang Sheng-Lyang
Published: October 2002

A new deep submicron I–V model for lightly-doped drain (LDD) and single-drain (SD) metal-oxide-semiconductor-field-effect-transistors (MOSFET) is presented. The physics-based and analytical model is developed using the drift-diffusion equation with a modified mobility formula to consider the effect of velocity overshoot and based on the quasi-two-dimensional Poisson equation. The drain-induced-barrier-lowering (DIBL), channel-length modulation, velocity overshoot, and parasitic source and drain resistances have been included in the model in a physically consistent manner. In this model, the LDD region is treated as a bias-dependent series resistance, and the drain-voltage drop across the LDD region has been considered in modeling the DIBL effect. This model is smoothly-continuous and valid in all regions of operation, its accuracy has been checked by comparing the calculated drain current, conductance and transconductance with the experimental data.
The Effect of Li, Cu and Zn Doping on the Luminance and Conductivity of Blue ZnGa 2O 4 Phosphor
Authors: Yang Su-Hua , Yokoyama Meiso
Published: October 2002

This study investigates the doping effect of Li, Cu or Zn on the luminescence and
conductivity characteristics of ZnGa2O4 phosphor. The X-ray
diffraction (XRD) patterns reveal a negligible difference in peak positions and values of full-width at half
maximum (FWHM) under various synthetic parameters, indicating that an excellent
solid solution exists between the additives and the ZnGa2O4 phosphor. Doping of Li or
Zn increases the oxygen vacancy concentration in the phosphor. Therefore, Li or Zn
doping enhances the luminance and conductivity of ZnGa2O4 phosphors. However,
doping of Cu ions increases the scattering and trapping probabilities of electrons,
thereby decreasing the conductivity, and results in a decreased luminescence of
ZnGa2O4 phosphor. As-prepared low-voltage phosphors show blue-emission,
appropriate to the application in the field emission display (FED).
Simulations of Wearless Friction at a Sliding Interface between Ordered Organic Monolayers
Authors: Ohzono Takuya , Glosli James N. , Fujihira Masamichi
Published: October 2002

Molecular dynamics and simple phenomenological simulations are used to model the
friction between two ordered monolayers of alkane chains bound at their ends to rigid
substrates. Results of calculations using these methods suggest that the frictional properties at
a sliding interface between the ordered films are governed by two simplified potentials. One
is a potential due to the lateral collective deformation of a film and the other is a corrugated
interfacial potential between films facing each other. These two potentials are closely related
to the nature of the films, i.e., their physical and chemical properties. In addition, the
simplified models can be greatly extended to clarify the frictional behavior of other weakly
interacting interfaces such as hydrogen-terminated diamond surfaces.
High-Quality Epitaxial MnSi(111) Layers Grown in the Presence of an Sb Flux
Authors: Matsuda Koji , Tatsuoka Hirokazu , Matsunaga Kazuharu , Isaji Koji , Kuwabara Hiroshi , Brown Paul D. , Xin Yan , Dunin-Borkowski Rafal , Humphreys Colin J.
Published: October 2002

MnSi epitaxial layers have been grown on (111) and (001)-oriented Si substrates by Mn
deposition and reaction with Si in the presence of an Sb flux. Characterization using
transmission electron microscopy (TEM) confirmed the formation of high-quality epitaxial
layers with smooth interfaces between the MnSi and the Si(111) substrate, when grown
under optimal conditions, without the deposition of elemental Sb or Sb-based compounds.
MnSi layers are found to be rotated 30° with respect to the Si(111) substrate to reduce
the lattice mismatch. Evidence only for the presence of MnSi was found and there was no
evidence of any other Mn–Si phases. The additional formation of MnSb is found to
depend on the rate of formation of MnSi, which is primarily governed by the Mn flux rate
and the growth temperature. By way of comparison, polycrystalline mixed phase Mn-silicide layers were formed by direct deposition of Mn and reaction with Si(111) at
elevated temperatures in the absence of an Sb flux.
Elastic Scattering of 12C by 12C at Intermediate Energies
Authors: Sayed Khallaf Sayed Khallaf , Mamdouh Abdelrahman Mamdouh Abdelrahman , Saad Abdelraheem Saad Abdelraheem , Safwat Mahmoud Safwat Mahmoud
Published: October 2002

Using the double folding model (DF), the real part of the central optical potential for the 12C + 12C system is derived. This potential as well as the single-folding cluster model potential (SFC) are used to calculate the total and differential cross sections for 12C elastically scattered on 12C at three laboratory energies, E
lab. = 300, 344.5 and 360 MeV. The calculations are carried out with five sets of nucleon-nucleon (NN) interaction of the integrable Gaussian form and two sets of parameters for the nuclear matter density of the harmonic oscillator form. The transparency of the target nucleus is found to increase as the projectile energy increases. Good fits between the present calculations and the experimental data, as well as with previous calculations, are obtained. The simple methods used here for calculating the real part of the optical potential reduce the potential computing time enormously. The suitable choice of NN interaction as well as nuclear matter densities is important.
Characteristics and Reduction of Noise in Scanning Hot Electron Microscopy
Authors: Nobutaka Kikegawa Nobutaka Kikegawa , Kazuhito Furuya Kazuhito Furuya , Francisco Vazquez Francisco Vazquez , Yoshihiro Ikeda Yoshihiro Ikeda
Published: October 2002

Scanning hot electron microscopy (SHEM) is a method for observing the
subsurface hot electron (HE) distribution in a solid. SHEM requires that both the HE and thermal-equilibrium electron (TE) currents flow through the tip current circuit. To obtain a large HE current, the top of the potential energy in the tip-sample gap region is lowered below the HE energy by the approach of the tip toward the sample and/or the increase in the voltage applied across the gap. However, even under this condition, the HE current is about one thousandth of the TE current. To improve the HE detection ability for SHEM, in this paper dependencies of the noise current caused by the gap space fluctuation on related parameters have been theoretically derived. Furthermore in the Au/Air/W structure, the power spectral density of the tunnel current is measured for SHEM. The noise current is proportional to the tunnel current as shown by theory. From the results, conditions for the observation of hot electrons are clarified.
Allene-Doped Liquid Ar Homogeneous Calorimeter for Measurement of Heavy Ion Fragmentation
Authors: Hiroyuki Okada Hiroyuki Okada , Tadayoshi Doke Tadayoshi Doke , Peter Egelhof Peter Egelhof , Toshisuke Kashiwagi Toshisuke Kashiwagi , Jun Kikuchi Jun Kikuchi , Misaki Kobayashi Misaki Kobayashi , Kimiaki Masuda Kimiaki Masuda , Manfred Mutterer Manfred Mutterer , Sigurd Neumaier Sigurd Neumaier , Eido Shibamura Eido Shibamura , Kazuhiro Terasawa Kazuhiro Terasawa , Achim Weinbach Achim Weinbach
Published: October 2002

An allene-doped liquid argon calorimeter whose electrode consists of thin multi parallel plates has been used to measure charge-changing cross sections of 58Ni ions with energies of 400–500 MeV/nucleon.
In this calorimeter, the energy loss distribution along the particle track was measured until the major particles stopped.
The atomic number of the secondary particles was precisely determined and the total and partial charge-changing cross sections were obtained.
The Role of Sub-Target in the Transversely Excited Atmospheric Pressure CO 2 Laser-Induced Shock-Wave Plasma
Authors: Suliyanti Maria M. , Hedwig Rinda , Kurniawan Hendrik , Kagawa Kiichiro
Published: October 2002

A transversely excited atmospheric pressure (TEA) CO2 laser pulse (50 mJ, 100 ns) was focused on silicon grease which is painted on a copper plate as a subtarget with a power density of 6 GW/cm2 under reduced pressure. The comparison of the characteristics of the induced laser plasma between two cases,
with subtarget and without subtarget was made. It is proved that the emission
spectrum assigned to the silicon atom can be detected only for the case with the
subtarget. It is also proved that in the absence of the subtarget, the gushing
speed of the atom is very low, while for the case with subtarget, the gushing
speed of atoms becomes very fast. It is shown that the setting of subtarget is
very effective for producing laser-induced shock wave plasma and it is very
effective for the realize quantitative analysis of a soft material.
Orientational Changes of Side Chain Nonlinear Chromophore in Polyimide Langmuir-Blodgett Films
Authors: Cheolsoo Jung Cheolsoo Jung , Byoungchoo Park Byoungchoo Park , Mitsutoshi Jikei Mitsutoshi Jikei , Hideo Takezoe Hideo Takezoe , Masa-aki Kakimoto Masa-aki Kakimoto
Published: October 2002

The orientational changes in optical nonlinear active side chains of
polyamic acid alkyl amine salt monolayers before and after the imidization
process were studied by optical surface second-harmonic generation
(SHG). The polymeric Langmuir-Blodgett (LB) monolayer composed of the
triphenylamino-(p-nitrophenyl)-ethylene group as a side chain of
polyamic acid was prepared by the precursor method.
The analysis of the experimental results showed that the symmetry of
the side chain unit in the monolayer remains C
∞v
after
imidization process. Moreover, the side chain molecular orientational
distribution functions (ODFs) of the
polymeric monolayer before and after imidization were obtained
using the modified maximum entropy method. From the obtained ODFs, it
was found that the polar angle of the side chain increases by imidization
and this causes the decrement of the nonlinear optical components. However the
half-width (Δθ) of the major molecular tilt angle decreases
by imidization, suggesting that the distribution of the chromophore is
more uniformly packed through the imidization process.
Reticle Critical Dimension Latitude for Fabrication of 0.18 µm Line Patterns
Authors: Matsuura Seiji , Uchiyama Takayuki , Fujimoto Masashi , Yamazaki Tamio , Hashimoto Takeo , Kasama Kunihiko
Published: October 2002

The reticle critical dimension (CD) latitude of 0.18 µm line patterns with various pitches was
investigated from the standpoint of mask linearity, optical proximity effect (OPE) and depth of
focus (DOF). We propose a global reticle CD latitude which is defined by the common range of
allowable reticle CDs for various pitches. The global reticle CD latitude was enhanced under
illumination conditions in which the OPE was suppressed, e.g., conventional illumination, and at
the optimum numerical aperture (NA) which gave a wider DOF, especially for isolated lines. We
found experimentally that the global reticle CD latitude (on x4 reticle, range) of 0.18 µm line
patterns was 20 nm at NA=0.60 and σ=0.75 conventional illumination. Furthermore, from aerial
image simulation results, the global reticle CD latitude was expected to be enhanced at the
optimum NA (∼0.68) by KrF, and at 0.60 NA by ArF lithography.
Measurement Method for Odd Component of Aberration Function Utilizing Alternating Phase Shift Mask
Authors: Nakao Shuji , Miyazaki Junji , Tsujita Kouichirou , Wakamiya Wataru
Published: October 2002

A novel measurement method for an odd component of an
aberration function utilizing an alternating phase shift
mask (PSM) is proposed based on optical image calculations.
When high coherent illumination is applied, lateral fringe
shift in the image, which is formed with lines and
spaces(L/S) patterns of alternating PSM, is caused by the
phase difference between two beams in interference. The
shift distance is simply expressed by a quotient of the
phase difference (measured in distance) and sine of the beam
incident angle. Thus, by measuring the fringe shift
distance by changing the pattern pitch, the odd component of
the aberration function can be derived. To measure the
fringe shift distance, a test device structure utilizing a
modified MOS process is considered. By fabricating the test
structure under the appropriate optical conditions and
measuring the capacitances of the MOS structure, the fringe
shift distance could be measured with high accuracy.
Proposal for the Coma Aberration Dependent Overlay Error Compensation Technology
Authors: Asai Naoko , Hasegawa Norio , Gotoh Yasuko , Satoh Hidetoshi , Hayano Katsuya , Imai Akira , Okazaki Shinji
Published: October 2002

A new method for overlay accuracy improvement which compensates for the positional
shifts of patterns due to coma aberrations, using the pattern placement error-corrected mask is
proposed. Various types of resolution enhancement technologies such as modified illumination
and phase shifting techniques significantly improve the resolution. The effects of residual
aberrations in the lens system cannot be ignored because such resolution enhancement
technologies emphasize the effects of the aberrations in the projected images. One of the key
issues is the deterioration of the positional accuracy due to coma aberrations. As the positional
shifts of patterns heavily depend on the spatial frequency of the pattern and the illumination
conditions. 2.0-µm isolated line patterns and 0.3-µm line-and-space patterns are selected and
their pattern shift examined. Two types of correction methods were investigated in this work
using the pattern placement error-corrected mask, the absolute correction and the relative
correction method. By the use of these correction methods, the overlay errors due to coma
aberrations can be reduced to half of the error obtained without application of these correction
methods.
Study of the Bottom Antireflective Coating Process Using a High-Transparency Resist for ArF Excimer Laser Lithography
Authors: Kishimura Shinji , Takahashi Makoto , Ohfuji Takeshi , Sasago Masaru
Published: October 2002

We have investigated the effect of substrate reflectivity and resist transparency on resist
performance in ArF excimer laser lithography with bottom antireflective coating (BARC).
Both depth-of-focus (DOF) and exposure latitude in low-transparency (49% per 0.5 µm
thickness) resist were improved as the substrate reflectivity was decreased. However, the
DOF and the exposure latitude decreased, since the resist profile was tapered on the extremely
low-reflectivity (∼0%) substrate. On the other hand, the DOF of high-transparency (67% per
0.5 µm thickness) resist was wider than that of low-transparency resist and was independent of
substrate reflectivity. The exposure latitude also improved with decreasing reflectivity.
High-transparency resist achieved a 0.75 µm DOF at 0.15 µm lines and spaces (L/S) on
BARC using a 0.60-NA lens without any resolution enhancement techniques. Good critical
dimensional control at 0.15-µm L/S patterns over the topography with 200-nm step was
obtained without significant linewidth variation. Gate etching was successfully achieved
down to 0.11 µm L/S with the etching conditions developed for KrF resists.
Ring-Field Extreme Ultraviolet Exposure System Using Aspherical Mirrors
Authors: Murakami Katsuhiko , Oshino Tetsuya , Kinoshita Hiroo , Watanabe Takeo , Niibe Masato , Ito Masaaki , Oizumi Hiroaki , Yamanashi Hiromasa
Published: October 2002

We have designed and started the fabrication of 3-mirror ring-field projection optics
for extreme ultraviolet lithography (EUVL) and an experimental exposure system using the
projection optics, which enable a large-field (30 mm×20 mm), high-resolution (<100 nm)
exposure. EUV exposure experiments will be performed using the EUVL beam line to be
constructed at the new synchrotron ring called New Subaru, which is now under construction
in Hyogo Prefecture. In this paper the details of the EUV exposure
system will be described.