bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Fiber Bragg Gratings using the Lattice Filter Model
Authors: Bae Jinho , Chun Joohwan , Lee Sang Bae
Published: October 2002

We propose a new method for analyzing fiber Bragg gratings with an arbitrary index profile and an arbitrary individual grating length. The proposed method is based on the lattice filter model which is widely used in applications ranging from digital filtering to speech synthesis and explosive seismic signal processing. Lattice filter interpretation provides us with an accurate and simple tool for analyzing an arbitrary index profile and arbitrary aperiodic fiber grating structures, and gives us further insight into the understanding of fiber Bragg gratings. To verify the validity of the proposed model experimentally, we have fabricated two grating structures; the short-period (periodic) fiber Bragg grating structure and the chirped fiber Bragg grating structure. We have observed that the calculated transmission spectrum and the calculated reflectivity using our lattice filter model match very closely to the corresponding measured spectrum in the wavelength band of interest.
Difference-Frequency Generation in MgO-Doped Periodically Poled LiNbO3 Using an Electronically Tuned Ti:Sapphire Laser in Dual-Wavelength Operation
Authors: Saito Norihito , Wada Satoshi , Taniguchi Hirokazu , Nakamura Masaru , Urata Yoshiharu , Tashiro Hideo
Published: October 2002

Tunable mid-infrared radiation was generated by difference-frequency generation
in MgO-doped periodically poled LiNbO3 crystal by mixing of dual-wavelength
pulses emitting from a Ti:sapphire laser, which was tuned with an intracavity
acousto-optic tunable filter. A tuning range from 3.6 to 5.6 µm was obtained
without any mechanical rotation of the nonlinear optical crystal and other laser elements.
Fundamental Absorption Edge of α-AgI-type Superionic Conductor Ag3SBr
Authors: Wakamura Mitsufumi Kurita
Published: October 2002

The photoacoustic spectrum (PA) of the superionic conductor Ag3SBr has been measured in the range of 0.7–4.5 eV at room temperature. From the PA signal, the band gap energy E
g has been assigned to be 1.85 eV, the magnitude of which is between those of Ag3SI and AgBr. This value is ascertained from the darkening phenomenon and optical dielectric constant ε∞.
Influence of Defect Segregation on the Electrical Properties of Nb-doped SrTiO3 Grain Boundary Layer
Authors: Kim Seong-Ho , Suh Jun-Hyuk , Park Jae-Gwan , Kim Yoonho
Published: October 2002

The influences of defect segregation on electrical properties were
investigated for a single grain boundary layer in Nb-doped SrTiO3. The
electrical properties were compared with those of a grain embedded with a
platinum wire. On the basis of the current–voltage (I–V)
characteristics, it was found that the
grain boundary of Nb-doped SrTiO3 could be presented as a
back-to-back double
Schottky model. The segregation of defects, strontium
vacancies, in grain boundary was suggested from the results of
currnet–time (I–t) measurement, impedance spectroscopy, and
capacitance–voltage (C–V) measurement. It was also postulated that
the
space charge originating from this defect segregation forms the potential
barrier. The activation energy for conduction through a grain boundary
changed with applied voltage from 1.60 eV to 0.97 eV.
Adsorption of Fluorine on Bare, Hydrogen- and Hydrocarbon-Covered Diamond C(111) Surfaces
Authors: Yamada Taro , Seki Hajime , Chuang Tung J.
Published: October 2002

The adsorption of fluorine delivered as xenon difluoride has been examined on a
bare diamond C(111)(2×1) surface as well as modified surfaces of
hydrogen-terminated H:C(111)(1×1) and hydrocarbon-precovered
CH
x
/C(111) by means of Auger electron spectroscopy (AES), X-ray photoelectron
spectroscopy (XPS) and low-energy electron diffraction (LEED). The F intake by bare
C(111)(2×1) at nearly 105 Langmuir of XeF2 exposure reached close
to two monolayers on C(111). The adsorbed F was removed by annealing to 1400 K in
vacuum, and was replaced by atomic hydrogen generated by a hot filament. The
saturation coverage of F on H:C(111)(1×1) was one monolayer. The adsorbed F
on H:C(111)(1×1) was removed by annealing to 1300 K and
H:C(111)(1×1) was restored. On C(111) precovered with CH
x
groups, the
initial sticking probability of F was definitely smaller than that of
C(111)(2×1). The adsorbed F was less stable and desorbed completely at
1200 K. The structures of adsorbed F on C(111)(2×1) and
H:C(111)(1×1) are discussed.
Standardization of Detector Control Systems
Authors: Chikara Fukunaga Chikara Fukunaga
Published: October 2002

Current and future detectors for high-energy and/or nuclear physics experiments require highly intelligent detector control systems. In order to reduce resources, the construction of a standardized template for the control systems based on the commercially available superviser control and data acquisition (SCADA) system has been proposed. The possibility of constructing this template is discussed and several key issues for evaluation of SCADA as the basis for such a template are presented.
On Landau Damping by Bunch Filling Pattern in the Pohang Light Source Storage Ring
Authors: Yujong Kim Yujong Kim , Mi Kyung Park Mi Kyung Park , Jung-Yun Huang Jung-Yun Huang , Myeun Kwon Myeun Kwon , Won Namkung Won Namkung , In Soo Ko In Soo Ko
Published: October 2002

The stable beam current of the Pohang Light Source (PLS) is normally limited to about 150 mA despite the design value of 400 mA at 2.0 GeV due to the coupled bunch mode instabilities (CBMIs) which are generated by the interaction between higher order modes of RF cavities and circulating beams. In order to improve this situation, a longitudinal feedback system (LFS) using parallel digital signal processors was installed during the summer maintenance period in 1999. Besides the cure of the CBMIs, this programmable LFS is useful for various beam diagnostics such as the synchrotron oscillation phases and their spreads, and the beam pseudo-spectra that are the beam spectra without beam revolution harmonics. With this bunch-to-bunch diagnostic information, it is found that properly arranged bunch filling patterns can increase the stored beam current significantly without an active longitudinal feedback due to Landau damping by bunch-to-bunch synchrotron frequency spreads.
Contrast Enhancement based on Acid Equilibrium for Chemically Amplified Resists
Authors: Keisuke Nakazawa Keisuke Nakazawa , Masaru Sasago Masaru Sasago
Published: October 2002

We have developed a method of enhancing the resist contrast governed by the hydrogen-ion concentration in chemically amplified resist films. We consider the distribution of permittivity and the equilibrium constants of acids generated by photoirradiation. The hydrogen-ion concentration in a resist film containing a weak acid increases with increasing permittivity. If the permittivity of exposed areas is higher than that of unexposed areas, the resist contrast is greater than that of resist films whose permittivity is the same in both exposed and unexposed areas. Accordingly, the resolution capability is enhanced and the depth of focus is increased. Calculations based on a model in which an additive whose polarizability is increased by photoirradiation is mixed within the resist, indicated that (1) the resist contrast depends on the amount of polarizability change and the concentration of the additive, (2) the resist contrast takes a maximum value at an optimum exposure dose, and (3) an appropriate combination of available additives and available exposure doses can result in a resist contrast higher than that obtained when strong acids are generated and also higher than the optical contrast.
A New Method to Estimate the Position of Electron Avalanche in Proportional Counter
Authors: Maeda Nobuhiro , Ito Shin , Isozumi Yasuhito
Published: October 2002

We have developed a new method to estimate the position of an electron
avalanche in the proportional counter. In the counter chamber, two parallel wires are
located on both sides of the anode with a slope and the charge is partitioned by these
two wires. The position of the avalanche is determined from the charge ratio. The
position resolution is about 2 mm full width half maximum (FWHM).
Leakage Mechanism of Local Junctions Forming the Main or Tail Mode of Retention Characteristics for Dynamic Random Access Memories
Authors: Shuichi Ueno Shuichi Ueno , Yasuo Inoue Yasuo Inoue , Masahide Inuishi Masahide Inuishi , Natsuro Tsubouchi Natsuro Tsubouchi
Published: October 2002

We have reported the test structure for measuring the leakage characteristics of the local junctions. In this paper, we analyze the measurement results of the leakage characteristics of local pn junctions. We determined that the trap-assisted tunneling mechanism controls the leakage current of the main mode cells. It is observed that the increment of the leakage current at the leaky junctions in the tail mode is smaller than that at the normal junctions in the main mode when the supply voltage is increased. We propose a two-traps related leakage mechanism for the leakage current of the pn junctions in the tail mode. The two-traps pair increases the leakage current and forms the tail mode in the distribution of retention time of the dynamic random access memories.
Influence of Thermal Noise on Drain Current in Very Small Si-MOSFETs
Authors: Sano Nobuyuki , Matsuzawa Kazuya , Mukai Mikio , Nakayama Noriaki
Published: October 2002

We investigate the intrinsic current fluctuations in very small
Si-metal-oxide-semiconductor field-effect-transistors (MOSFETs)
using Monte Carlo device simulation.
It is demonstrated that the temporal fluctuation
of the drain current in small Si-MOSFETs
attains a significant fraction of the
averaged drain current when the device width is scaled down to the deep
sub-µm regime.
This enhancement of current fluctuation
is caused by the drastic decrease in the number of channel electrons
underneath the gate.
It is also demonstrated that current fluctuation is
physically associated with
the quasi-equilibrium thermal noise in the heavily doped source
and drain regions.
More significantly, the current fluctuation is intrinsically unavoidable and
could be a critical issue for further device shrinkage.
New Excimer Laser Recrystallization of Poly-Si for Effective Grain Growth and Grain Boundary Arrangement
Authors: Jeon Jae-Hong , Lee Min-Cheol , Park Kee-Chan , Han Min-Koo
Published: October 2002

A new excimer laser recrystallization of polycrystalline silicon thin film is proposed to
increase the grain size and control the grain boundary locations. The
proposed method utilizes the lateral grain growth employing a masking
window during excimer laser irradiation. We designed a specific
laser-masking window to maximize the lateral growth effect and arrange
the location of grain boundaries. As a result of laser irradiation
through the opened gap in the masking window, we obtained
polycrystalline silicon film with the grain size exceeding 1 µm
and also observed well-arranged grain boundaries by transmission
electron microscopy. To enhance the overall grain quality of the film,
the second laser irradiation without masking window was carried out to
recrystallize the residual amorphous silicon regions shaded by the
masking patterns during the first laser irradiation. Thin film
transistors fabricated by the proposed method showed considerably
improved electrical characteristics which directly
reflect the quality of polycrystalline silicon active layer.
Influence of Gate Oxide Quality on Plasma Process-Induced Charging Damage in Ultra Thin Gate Oxide
Authors: Okushima Mototsugu , Noguchi Ko
Published: October 2002

The correlation between the gate oxide quality and the plasma process-induced charging
damage is studied for metal-oxide-semiconductor (MOS) devices with
gate oxide thickness of 1.9–3 nm. It is found that plasma charging
damage of ultra thin oxide strongly depends on its initial oxide
quality. The ultra thin oxide of around 2 nm thick is not always free
from plasma charging damage, if the fabrication process other than the
plasma process is not optimized. A mechanism of the enhanced plasma
charging damage due to gate electrode formation process is
proposed. If defects exist in the oxide, these defects become weak
paths for the injected current during the plasma process. Thus,
current density at the defects becomes high and oxide breakdown occurs
even when the oxide is as thin as 2 nm, in which current conduction
by direct tunneling dominates.
Extendibility of Ta2O5 Metal-Insulator-Metal Capacitor Using Ru Electrode
Authors: Tsuzumitani Akihiko , Okuno Yasutoshi , Shibata Jun , Shimizu Tadami , Yamamoto Kazuhiko , Mori Yoshihiro
Published: October 2002

The electrical properties of the Ru/Ta2O5/Ru planar capacitor structure were
investigated. It was determined that the leakage current and temperature dependence
were improved using a bottom electrode annealed in Ar/H2 mixture
ambient. A step-and-terrace structure was obtained on the Ru surface
when annealed in Ar/H2 mixture ambient, unlike that obtained from the conventional inert ambient anneal. Since a
physical analysis of the two Ru bottom electrodes did not show any other difference, we
considered the difference in surface morphology to be one of the major reasons for the
improvement in temperature dependence of the leakage current. In addition, a
cylindrical bottom Ru electrode of 20 nm thickness and 0.3 µm height was
demonstrated, as the thin Ru film had sufficient physical strength to fabricate this
cylindrical structure. Using the obtained parameters, the Ru thickness, the dielectric
leakage and other characteristics, from the experimental results, we discussed the
extendibility of the Ta2O5-MIM capacitor structure. By assuming the effective
thickness of Ta2O5 to be 0.9 nm and capacitance to be 25 fF/cell, an electrode height of
0.7 µm was expected with a leakage current of less than
1 fA/cell at the 0.1-µm-node cylindrical structure.
Ferroelectric Properties of Pb(Zi, Ti)O3 Capacitor with Thin SrRuO3 Films within Both Electrodes
Authors: Morimoto Toyota , Hidaka Osamu , Yamakawa Kouji , Arisumi Osamu , Kanaya Hiroyuki , Iwamoto Tsuyoshi , Kumura Yoshinori , Kunishima Iwao , Tanaka Shin-ichi
Published: October 2002

Ferroelectric properties of a Pb(Zi, Ti)O3 (PZT) capacitor
with thin SrRuO3(SRO) films within both electrodes were
investigated in detail. Thin SRO films of 10 nm thickness markedly
improve the electrical performance, such as switching charge (Qsw),
saturation characteristics of the hysteresis curve and imprint
performance even at an elevated temperature. It should also be
noted that there was no Qsw degradation after 5×1010 read/write cycles at 5 V. No leakage current increase
after the test was observed. The results of transmission electron
microscope (TEM) and electron dispersive X-ray (EDX) analyses also
showed that there is no diffusion of either Sr or Ru in the PZT
film. The Qsw increase can be explained by the model in which excess
oxygen ions existing in the SRO films drift into the PZT due to the
external electric field where they fill the oxygen vacancies in the
PZT near the interfaces. We confirmed that the proposed electrode
structure was a key to realizing highly reliable ferroelectric
random access memories (FRAMs).
An Improvement in C–V Characteristics of Metal-Ferroelectric-Insulator-Semiconductor Structure for Ferroelectric Gate FET Memory Using a Silicon Nitride Buffer Layer
Authors: Hideki Sugiyama Hideki Sugiyama , Toshiyuki Nakaiso Toshiyuki Nakaiso , Yuji Adachi Yuji Adachi , Minoru Noda Minoru Noda , Masanori Okuyama Masanori Okuyama
Published: October 2002

Metal-ferroelectric-insulator-semiconductor (MFIS) structures using silicon nitride (SiNx) and silicon oxynitride (SiON) layers as an insulating barrier against interdiffusion have been proposed and investigated. SrBi2Ta2O9 (SBT) films are deposited as ferroelectric layers by pulsed laser deposition (PLD) method on SiNx/SiO2/Si and SiON/Si substrates at low temperatures. An Al/SBT/SiNx/SiO2/Si (MFNOS) structure exhibits a larger memory window and a smaller shift in C–V curve than those of the Al/SBT/SiO2/Si structure. Moreover, strong barrier effect of SiNx layer is demonstrated by both Rutherford back scattering spectroscopy (RBS) analysis and comparison of two Al/SiNx/SiO2/Si structures with and without depositing SBT film. An Al/SBT/SiON/Si (MF(ON)S) structure also shows good C–V characteristics with no degradation in the curve gradient. In addition, the C–V curve shows no change when the sweep rate of the bias voltage is increased from 0.2 V/s to 40 kV/s, which indicates that the hysteresis originates not from ion drift but from high-speed ferroelectric polarization.
Impact of Nitrogen Implantation in Lightly Doped Drain (NIL) on Deep Sub-Micron CMOS Devices
Authors: Sung-Kwon Hong Sung-Kwon Hong , Sang-Gi Lee Sang-Gi Lee , Kyong-Ha Lee Kyong-Ha Lee , Jae-Gyung Ahn Jae-Gyung Ahn , Jung-Hwan Son Jung-Hwan Son , Dae-Gwan Kang Dae-Gwan Kang , Jeong-Mo Hwang Jeong-Mo Hwang
Published: October 2002

In this study, we investigate the device characteristics of
lightly doped drain (LDD) metal-oxide-semiconductor field effect
transistors (MOSFETs) with nitrogen implantation in the gate
overlapped LDD region. As expected, the hot carrier lifetime under
drain avalanche hot carrier (DAHC) stress condition is sufficiently
improved in nMOSFETs with nitrogen implantation as part of the LDD
(NIL) technique. However, the nitrogen-enhanced short channel effect
is observed. The function of nitrogen atoms in pMOS devices has
theopposite characteristic. In addition, the effective channel
lengths shift in opposite directions in nMOSFET and
pMOSFET. Off-state currents of NIL nMOSFET are degraded, resulting
in the deterioration of the short channel length margin
characteristic, while the short channel length margin is improved in
NIL pMOSFET.
Measurement of Copper Drift in Methylsilsesquiazane-Methylsilsesquioxane Dielectric Films
Authors: Mukaigawa Seiji , Aoki Tomoko , Shimizu Yasuo , Kikkawa Takamaro
Published: October 2002

Measurement of Cu drifts in methylsilsesquiazane-methylsilsesquioxane
dielectric films in the presence of an electric field was conducted
using bias-temperature stress (BTS) and capacitor-voltage (C
V) analysis
as well as time dependent dielectric breakdown (TDDB) stress.
The amount of Cu ions in the dielectric films can be estimated
making use of the flatband voltage shift ΔV

F
B
from the
BTS.
Comparing the flatband voltage measured by C
V analysis with the
leakage current integrated over time,
it is found that the main content of the leakage current during BTS
is ionic current that can be attributed to the drift of Cu and mobile ions.
The Cu ions cause the leakage current during TDDB stress to increase.
The drift rate of Cu in methylsilsesquioxane is lower than the reported
values in polyarylene ether (PAE) and fluorinated polyimide (FPI),
and larger than that in plasma enhanced chemical vapor deposition
(PEC
VD)-SiON.
Preparation of Pt/Ru Bilayers and Their Application to the Capacitor of Memory Devices
Authors: Soo Lee Byung , Chul Choi Young
Published: October 2002

Pt(100 nm)/Ru(80 nm) bilayers were prepared on SiO2/Si substrates by RF magnetron sputtering. Pt films were deposited on Ru layers at temperatures ranging from 300°C to 450°C, while the deposition temperature of Ru films was fixed at 300°C. The Ru layer was found to act as a diffusion barrier as well as a glue layer. With increasing deposition temperature, the grain size of Pt increased. However, the Pt film deposited at 450°C had many voids. In the temperature range from 300°C to 400°C, the sheet resistance of Pt/Ru bilayers linearly decreased with temperature, which is ascribed to increasing crystallinity and grain size. The Pt(450°C)/Ru bilayer, however, showed much higher resistance, caused by voids. Three different capacitors with the structures of Pt/(Ba,Sr)TiO3(BST)/Pt, Pt/BST/RuO2, and Pt/BST/Pt/Ru were fabricated and their properties were characterized. The microstructures of BST films were found to be affected by those of bottom electrodes, and to have an important effect on the electrical properties of the capacitor. The electrical properties, such as dielectric constant and leakage current density, of the capacitor with Pt/Ru bottom electrodes are analogous to those with Pt bottom electrodes and better than those with RuO2 bottom electrodes.
Comparison Between High- and Low-Dose Separation by Implanted Oxygen MOS Transistors for Low-Power Radio-Frequency Applications
Authors: Rozeau Olivier , Jomaah Jalal , Boussey Jumana , Omura Yasuhisa
Published: October 2002

In this work, metal-oxide-semiconductor (MOS) field effect
transistors (MOSFET) fabricated on low- and high-dose separation by
implanted oxygen (SIMOX) substrates are compared in terms of RF
performance. Combining S-parameter measurements with an accurate
extraction method of small-signal model parameters enables us to
investigate the RF performances of these two technologies and to
evaluate the impact of the self-heating effect on silicon on
insulator (SOI) MOSFET performances in this range. The cut-off
frequency behavior of these two SOI MOSFET types is therefore
analysed. In addition, using an analytical model, the influence of
the buried oxide thickness on the coplanar transmission lines is
investigated. All these results show the potentiality of the
low-dose SIMOX technology for low-power radio-frequency
applications.
A Compactly Integrated Random-Signal Source Using Chaos Multivibrator
Authors: Tsujita Tatsuo , Fujishima Minoru , Hoh Koichiro
Published: October 2002

A novel random-signal source has been designed and fabricated by
using compelmentary metal-oxide-silicon (CMOS) chaos
multivibrator. When the outputs of two multivibrators are summed, a
signal with sufficient randomness was obtained. This circuit can be
integrated within an area comparable to that of 2 or 3 units of
flip-flop circuits and can be operated with a delay time nearly
equal to that of 3 stages of logic gates. These features promise the
useful application of this signal source in various novel
information-processing LSIs.
Cellular νMOS Circuits Performing Edge Detection with Difference-of-Gaussian Filters
Authors: Tatsuhiko Sunayama Tatsuhiko Sunayama , Masayuki Ikebe Masayuki Ikebe , Tetsuya Asai Tetsuya Asai , Yoshihito Amemiya Yoshihito Amemiya
Published: October 2002

Aiming at the development of high-speed image processors, we propose a cellular νMOS circuit that performs the processing of edge detection. The proposed circuit uses neuron MOS (νMOS) transistors for analog convolution operations with Gaussian-shaped kernel functions, which makes the circuit organization extremely simple as compared with that of conventional convolution circuits. Performances of the proposed circuit are evaluated by simulation program with integrated circuit emphasis (SPICE). The results show the usefulness of the cellular νMOS circuit in image-processing applications.
Novel Low-Power Switched-Current Matched Filter for Direct-Sequence Code-Division-Multiple-Access Wireless Communication
Authors: Togura Kenji , Kubota Koji , Nakase Hiroyuki , Masu Kazuya , Tsubouchi Kazuo
Published: October 2002

We have proposed the current-cut switched-current matched filter (CC-SIMF) with a low power consumption of less than 10 mW for mobile terminals in direct-sequence code-division-multiple-access. The parallel SIMF configuration is proposed for the reduction of the current transfer error accumulation in the conventional serial SIMF. In order to evaluate the fundamental operation of the parallel SIMF, we have designed and fabricated a 32-chip parallel SIMF using 0.8-µm complementary-metal-oxide-semiconductor (CMOS) technology. The autocorrelation performance of a 32-chip orthogonal m-sequence
has been clearly observed to be more than 5 Mcps. The measured
dynamic range is improved to 12 dB as compared with that of the
conventional SIMF, even though each current memory cell has a current
transfer error of over 10% per chip. Since the current sources in the
parallel SIMF can be reduced to be one-third of those in the serial SIMF,
the power consumption of the parallel SIMF can be reduced to one-third of
that of the serial SIMF.
Optimum Conditions of Body Effect Factor and Substrate Bias in Variable Threshold Voltage MOSFETs
Authors: Koura Hiroshi , Takamiya Makoto , Hiramoto Toshiro
Published: October 2002

The effects of body effect factor (γ) and substrate bias
(V
bs) in a variable threshold voltage metal oxide
semiconductor field effect transistor (VTMOS) have been
systematically examined by device simulation. The characteristics of
a VTMOS are significantly affected by the value of γ and the
V
bs difference (ΔV
bs) between the
active mode and the standby mode. Optimal γ and ΔV
bs to obtain higher on-current in the active mode and
lower off-current in the standby mode are derived. When off-current
in the active mode is limited, a larger ΔV
bs and
smaller γ are preferable to obtain a higher drive
current. When γ is fixed, |ΔV
bs| should be
as large as the breakdown and leakage current permits. When ΔV
bs is fixed for some reason, such as breakdown, the
optimum γ depends on the relationship between ΔV
bs and V
dd: γ should be larger when a
large |ΔV
bs| can be applied, while it should be
smaller when the |ΔV
bs| is small. The scalability
of VTMOS is also discussed and it is found that channel engineering
is strongly required in a scaled VTMOS. These results will greatly
help in designing ultra-low power VTMOS VLSIs, and the VTMOS could
be expected to survive in the 50 nm generation depending on the scaling scenario and applications.
Analytical Single-Electron Transistor (SET) Model for Design and Analysis of Realistic SET Circuits
Authors: Ken Uchida Ken Uchida , Kazuya Matsuzawa Kazuya Matsuzawa , Junji Koga Junji Koga , Ryuji Ohba Ryuji Ohba , Shin-ichi Takagi Shin-ichi Takagi , Akira Toriumi Akira Toriumi
Published: October 2002

In this work, we propose a compact, physically based, analytical
single-electron transistor (SET) model suitable for the design and
analysis of realistic SET circuits. The model is derived on the
basis of the “orthodox” theory of correlated single-electron
tunneling and the steady-state master equation method. The SET
inverter characteristics are successfully calculated using the model
implemented in the simulation program with integrated circuit
emphasis (SPICE). The hybrid circuit of SETs with
metal-oxide-semiconductor field-effect transistors (MOSFETs) is also
successfully simulated. By utilizing the model, it is clarified
that the drain-voltage-induced shift of the gate voltage dependence
of SET current reaches one-half of the drain voltage in the case of
a completely symmetric SET.
Change in the Electric Current Required to Sustain Steady Electroosmotic Flow in a Capillary
Authors: Osuga Toshiaki , Kitagawa Shinya , Sakamoto Hideo , Tsuda Takao
Published: October 2002

For electroosmotic flow (EOF) in a capillary, a method is
established to locate the frontal zone between the injected
and ejected solutions, based on the change in the electric current
required to sustain the EOF when there is a difference of electric
conductivity between the injected and ejected solutions. When
a certain voltage is applied between the two ends of a
capillary filled with a solution, the EOF is generated in
the capillary, the flow profile of which is flat, in contrast
to that of the Poiseuille flow. Although the EOF moves the frontal zone
with constant velocity, the monitored electric current
required to sustain the EOF under a constant
voltage is found to change according to a hyperbolic function
of time. By associating the injected and ejected solutions with
two resistances connected in series, an accurate account is given of
the change in the electric current while the frontal zone progresses
through the capillary.
Variable Threshold AlGaAs/InGaAs Heterostructure Field-Effect Transistors with Paired Gates Fabricated Using the Wafer-Bonding Technique
Authors: Kodama Satoshi , Furuta Tomofumi , Watanabe Noriyuki , Ito Hiroshi , Kanda Atsushi , Muraguchi Masahiro , Ishibashi Tadao
Published: October 2002

We investigated a novel field-effect transistor (HFET) structure with paired gates
(PGs), where one gate is above and the other below the channel, in
order to realize an HFET that accepts two gate input signals. Using
the wafer-bonding technique, we succeeded in fabricating AlGaAs/InGaAs
PG-HFETs on a 3-inch-diameter wafer. The static characteristics of the
fabricated HFET indicate that the drain current (I
D) is
controlled by the paired gates, providing maximum transconductance of
240 mS/mm. Since the drain current can be controlled by each gate
voltage independently, the PG-HFET functions as a variable threshold
HFET. It has also been confirmed from the drain-current transfer
characteristics in subthreshold region that the channel potential is
controlled much better by PGs with a subthreshold parameter
N
G of 1.4 (corresponding to subthreshold gate swing S of
84 mV/decade).
Development of Three-Dimensional Integration Technology for Highly Parallel Image-Processing Chip
Authors: Wook Lee Kang , Tae Park Tomonori Nakamura , Yoon Kim Hiroaki Shimazutsu , Hiroyuki Kurino Hiroyuki Kurino , Mitsumasa Koyanagi Mitsumasa Koyanagi
Published: October 2002

A new three-dimensional (3D) integration technology for realizing
a highly parallel image-processing chip has been developed.
Several LSI wafers are vertically stacked and glued to each other
after thinning them using this new technology. This technology can
be considered as both 3D LSI technology and wafer-scale 3D
chip-on-chip packaging technology. The effective packaging
density can be significantly increased by stacking the chips in a
vertical direction. Several key techniques for this 3D
integration have been developed. In this paper, we demonstrate
the highly parallel image sensor chip with a 3D structure. The 3D
image sensor test chip was fabricated using this new 3D
integration technology and its basic performance was evaluated.
Analysis of Microstructure of Polyamic Acid Alkylamine Salt Monolayers by Atomic Force Microscopy and Friction Force Microscopy
Authors: Jiro Hamaya Jiro Hamaya , Nobuyuki Wakayama Nobuyuki Wakayama , Mitsutoshi Jikei Mitsutoshi Jikei , Masa-aki Kakimoto Masa-aki Kakimoto
Published: October 2002

The surface microstructures of monolayers of polyamic acid alkylamine salts having long alkyl chains were analyzed by atomic force microscopy (AFM) and friction force microscopy (FFM). Two different aromatic structures of polyamic acids and four different single chain alkylamine structures were used for the preparation of polyamic acid alkylamine salt monolayers. Although single chain alkylamines tend to form an island-like domain structure, the homogeneous island-free surface structure of monolayers were observed for the long alkyl chain dimethylamine derivative. The island-like structure was formed by the coagulation of alkylamine during the film preparation process. It was found that the coagulation of alkylamine chains could be eliminated by the selection of the starting single chain alkylamine structure and by the conditions of monolayer deposition, such as surface pressure.
Investigation into the Role of Low-Temperature GaN in n-GaN/InGaN/p-GaN Double-Heterostructure Light-Emitting Diodes
Authors: Youn Doo-Hyeb , Son Sung-Jin , Lee Young-Ju , Hwang Soon-Won , Yang Jung-Ja , Lee Kang-Jae , Kim Jong-Hi , Jo Jang-Yeon , Yoo Ji-Beom , Choi Chul-Jong , Seong Tae-Yeon
Published: October 2002

The role of two-step low-temperature GaN (LT-GaN) layers was
investigated by cathodoluminescence, high resolution double crystal
X-ray diffraction, transmission electron microscopy, atomic force
microscopy, and current-voltage measurements. It was shown that the
introduction of the LT-GaN layer prevents In from evaporating from
InGaN during the high-temperature growth of p-GaN. The trasmission
electron microscopic (TEM) results showed that the LT-GaN hampers
dislocation propagation from the InGaN active layer into the p-GaN,
leading to reduction in the dislocation density in the p-GaN. The
use of the two-step LT-GaN resulted in an increase in the output
power of light-emitting diodes and a decrease in the operating
forward voltage.
Damage Due to Nitrogen Molecular Ions of GaN Heteroepitaxial Layers Grown on Si(001) Substrates by Molecular Beam Epitaxy Assisted by Electron Cyclotron Resonance
Authors: Yodo Tokuo , Tsuchiya Hironori , Ando Hironori , Harada Yoshinobu
Published: October 2002

We have observed that the intensity of plasma emission at 391 nm from nitrogen
molecular ions in nitrogen plasma is closely related to the crystalline quality and the
surface morphology of GaN heteroepitaxial layers grown on Si(001). When plasma
emission intensity is increased, the surface morphology is degraded, the
photoluminescence (PL) intensities of two donor bound exciton (D0X) emissions
from mixed crystal grains of wurtzite-GaN (α-GaN) and
zincblende-GaN (β-GaN) and of yellow emissions are abruptly decreased,
and the full-width at half maximum of the D0X is broadened. These reflect the
influences of damage due to nitrogen molecular ions. The damage generates nonradiative
centers. A small number of (001)- and (111)-oriented β-GaN crystal grains exist
in the layers, together with a large number of (0001)-oriented GaN.
PL efficiency from β-GaN is markedly higher than
that from α-GaN, probably because the majority of the carriers accumulate in
the β-GaN side at the interface between α- and β-GaN. The broad
PL emissions at 3.10 and 3.29 eV with weak intensities are not changed by the damage.
The peak energy position of the 3.29 eV emission almost coincides with that of
D0X(β-GaN). The damage is not easily eliminated even by high-temperature
growth at 900°C.
Microstructure and Superconducting Properties of Bi2-xPbxSr2CaCu2Oy Transformed from an Amorphous State under Different Oxygen Partial Pressures
Authors: Fujii Hiroki , Kumakura Hiroaki , Togano Kazumasa
Published: October 2002

We investigated the microstructure and superconducting properties of
Pb-substituted Bi-2212 [Bi2-x
Pb
x
Sr2CaCu2O
y
;
(Bi, Pb)-2212], that was transformed from an amorphous state under different oxygen
partial pressures (P
O2
=0, 0.01, 0.21 and 1 atm). At
P
O2
≥0.01 atm, the (Bi, Pb)-2212 phase was formed via the
(Bi, Pb)2Sr2CuO
y
phase, while neither (Bi, Pb)-2212 nor
Bi2-x
Pb
x
Sr2CuO
y
was obtained at P
O2
=0 atm. Even
the low P
O2
heat treatment, which was effective in increasing the
amount of Pb substituting for Bi in Bi-2212, did not enhance the amount of Pb
substituted by the transformation, compared with the conventional solid-state reaction
method. No (Bi, Pb)-2212 crystal showing a lamellar structure composed of modulated
and modulation-free regions was observed. Pb substitution resulted in the enhancement
of magnetization hysteresis and irreversibility field, which is probably due not to the
difference in microstructure but to the decrease in anisotropy.
Discontinuous Narrowing of VO2+Electron Spin Resonance Linewidth in (NH4)3H(SeO4)2Induced by Superionic Phase Transition
Authors: Kazuo Furukawa Kazuo Furukawa
Published: October 2002

The superionic phase transition in a single-domain crystal of (NH4)3H(SeO4)2is studied by means of Electron Spin Resonance using VO2+. A discontinuous narrowing of the linewidth is observed at its superionic transition point. This phenomenon can be regarded as a motional narrowing that originates in the dynamic fluctuation of the pyramidal SeO4tetrahedron which brings about superionic conductivity.
Phase-Error Considerations for the Practical Phase Code Multiplexed Holographic Memory
Authors: Kim Kyu-Tae , Cho Byung-Chul , Kim Eun-Soo
Published: October 2002

For analysis of an effective phase code multiplexing in a
holographic memory system, the Hadamard matrix (HAM) and the
pseudorandom phase code (PRC) are generated and used as a reference
beam. In computer simulations, the size of the address beam is fixed
to 32×32 pixels, and 0%, 5%, 10%, 15%, 20%, or 25%
phase error rate in a pixel is purposely added to the real phase
values in order to consider the nonlinear phase modulation
characteristics of the practical spatial-light modulator
(SLM). Crosstalks and signal-to-noise ratios (SNRs) are
comparatively analyzed for these two phase codes by calculating the
auto- and cross-correlation. The cross-correlation mean values of
the PRC and the HAM are 0.067 and 0.139, respectively, which means
that the SNR of the PRC is higher than the HAM.
Electrical Characteristics of the Contour-Vibration-Mode Piezoelectric Transformer with Ring/Dot Electrode Area Ratio
Authors: Yoo Juhyun , Yoon Kwanghee , Lee Yongwoo , Suh Sungjae , Kim Jongsun , Yoo Chungsik
Published: October 2002

Contour-vibration-mode Pb(Sb1/2Nb1/2)O3–Pb(Zr, Ti)O3
[PSN–PZT] piezoelectric transformers with different ring/dot electrode area ratios
were fabricated to the size of 27.5×27.5×2.5 mm3 by cold isostatic
pressing. The electrical properties and characteristic temperature rises caused by the
vibration were measured at various load resistances. Efficiencies above 90% with load
resistance were obtained from all the transformers. The voltage step-up ratio appeared
to be proportional to the dot electrode area. A 14 W fluorescent lamp, T5, was
successfully driven by all of the fabricated transformers. The transformer with
ring/dot electrode area ratio of 4.85 exhibited the best properties in terms of output
power, efficiency and characteristic temperature rise, 14.88 W, 98% and 5°C,
respectively.
Effect of Electrode Area on Equivalent Circuit of AT-Cut Quartz Resonator
Authors: Wu Long , Chen Ping-Cheng , Huang Cheng-Liang , Chu Sheng-Yuan , Song Hong-Tie
Published: October 2002

A quartz resonator can be modeled as a series circuit consisting
of an inductance (L), a capacitance (C), a resistance (R) in
parallel with a capacitor (C
0), which are related to the
dimensions, density, electrode area and elastic, dielectric and
piezoelectric constants of the quartz. In this paper, the derivation
of the equivalent circuit of a quartz resonator is briefly discussed
and results of extensive research on the relationship between
electrode area and equivalent circuit is presented. The main purpose
of this work is to make it more simple and easy for quartz circuit
design and application. The experimental results show that when the
dimensions of quartz are constant, C and C
0 are directly
proportional to the electrode area, and L and R are inversely
proportional to the electrode area.
Mixture Behavior and Microwave Dielectric Properties in the Low-fired TiO2–CuO System
Authors: Kim Dong-Wan , Park Byungwoo , Chung Jang-Hoon , Hong Kug Sun
Published: October 2002

The mixture behavior and microwave dielectric properties of
TiO2 doped with CuO sintered at around 900°C for 2 h were
investigated using X-ray powder diffraction and a network
analyzer. Low-fired TiO2 with 2% CuO had a quality factor of
14000, relative dielectric constant (ε
r) of
98, and a temperature coefficient of resonant frequency
(τf) of 374 ppm/°C. The microwave dielectric
properties of low-fired, CuO doped TiO2 could be interpreted by
observing the dielectric properties of CuO: high loss tangent
(tan
δ), low dielectric constant, and a negative temperature
coefficient of resonant frequency. The microwave dielectric
properties of low-fired, CuO doped TiO2 showed a dependence on
the mixture formation of TiO2 and CuO. More importantly, the
ε
r of low-fired TiO2 with CuO could be
predicted by the logarithmic mixing model. Therefore, the variation
of the microwave dielectric properties was attributed to the mixture
behavior of TiO2 and CuO.
Comparison of Ta2O5 Thin Films Deposited by “Off-axis” and “On-axis” Pulsed Laser Deposition Technique
Authors: Ninomiya Taro , Inoue Narumi , Kashiwabara Shigeru
Published: October 2002

The crystalline properties of Ta2O5 thin films deposited by an off-axis
aperture-installation-type pulsed laser deposition (PLD) technique are investigated and
the results are compared to those of films deposited by the conventional on-axis
technique. When the repetition frequency is lowered, the X-ray diffraction intensity of
(001) peak increases in both films. This tendency, however, is more pronounced in the
off-axis films. The dielectric constant of off-axis films fabricated at 20 Hz indicates
a high value of about 40, and is higher than the measured value of bulk Ta2O5.
Therefore, it is concluded that the off-axis aperture-installation-type pulsed laser
deposition technique is effective not only for decreasing the density of droplets, but
also for obtaining high-quality crystalline films.
Low-Energy Electron Diffraction and X-Ray Photoelectron Spectroscopy Studies of Sb-induced Reconstruction on Si(113)3×2 Surface
Authors: An Ki-Seok , Hwang Chan-Cuk , Park Chong-Yun , Kakizaki Akito
Published: October 2002

We investigated Sb-induced reconstruction on a Si(113)3×2 surface
using low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy
(XPS). Depending on the annealing temperature and Sb coverage, 1×1,
1×2+2×, 2×2, and 2×5 structures were observed.
The 2×2 and 2×5 structures showed reversible phase transitions to
1×2 and 1×5 structures respectively at high temperature. The relative
Sb coverages of the 1×1 and 2×2 structures formed by annealing at
about 400 and 700°C were measured from Sb 3d/Si 2p core-level XPS intensity
ratios.
Metalorganic Chemical Vapor Deposition of Conductive CaRuO3 Thin Films
Authors: Higashi Noriyuki , Okuda Norikazu , Funakubo Hiroshi
Published: October 2002

CaRuO3 thin films expected for use as an electrode of ferroelectric
random-access memory were prepared for the first time by metalorganic chemical
vapor deposition (MOCVD) from the bis(dipivaloylmethanato)calcium(tetraen)
[Ca(C11H29O2)2(C8H23N5)
x
]–tris(dipivaloylmethanato)ruthenium [Ru(C11H29O2)3]–O2
and the bis(dipivaloylmethanato)calcium(tetraen) [Ca(C11H29O2)2(C8H23N5)
x
]–bis(ethylcyclipentadienyl)ruthenium Ru[(C5H4)(C2H5)]2–O2 systems. Epitaxial films were obtained on (100)LaAlO3 and (100)SrTiO3
substrates at 750°C, while randomly oriented films were obtained on a (100)MgO
substrate. The resistivity of these films was about
200 µΩ·cm, and was confirmed to be independent of film
thickness ranging from 70 to 300 nm. This value is lower than that of SrRuO3
thin films, about 280 µΩ·cm.
Linear and Nonlinear Ultrasonically Induced Birefringence in Polymer Solutions
Authors: Matsuoka Tatsuro , Koda Shinobu , Nomura Hiroyasu
Published: October 2002

Ultrasonically induced birefringence in polystyrene-toluene
solution was measured as a function of intensities. The
birefringence signal was observed by the “nonbiased” and
“biased” detection techniques. The values of birefringence
obtained by the nonbiased detection technique were proportional to
the ultrasonic amplitude, that is, the square root of the ultrasonic
intensity and their intensity dependence was in accordance with
those obtained by Jerrard (Ultrasonics 2 (1964) 74). The
birefringence signal was successfully observed by the biased
detection technique and its value was proportional to the square of
the ultrasonic amplitude, that is, the ultrasonic intensity. In
polymer solutions, two types of birefringence were induced; one was
due to linear and the other was due to nonlinear origins.
Heat Conduction in Nano-Environment Observed in Cooling Processes of Colloidal Silver Nanoparticles in Water
Authors: Harata Akira , Taura Jyunya , Ogawa Teiichiro
Published: October 2002

Ultrafast dynamics of colloidal silver nanoparticles in an
aqueous solution was investigated by observing the ultrafast lensing
effects caused by a photo-induced refractive index change. The
ultrafast response consisted of an instantaneous peak by the optical
Kerr effect and a subsequent bi-exponential decay component. The
decay component was independent of the relative polarization planes
of pump and probe beams and had temperature-dependent time constants
ranging from 0.4 to 2.2 ps and from 10 to 100 ps. A minimum at
around 7°C was found for the time constant of the fast
component. The results suggest that the structure of water molecules
adjacent to the silver surface is affected by hydrogen bonds in a
temperature-dependent manner similar to that of the molecular
structure of bulk water.
Frequency Dispersion in Elastic Property During the Glass Transition of Dehydrated Polyacrylamide Gel
Authors: Hara Kazuhiro , Nakamura Atsushi , Hiramatsu Nobuyasu , Matsumoto Akihiro
Published: October 2002

The elastic property evolution with increasing temperature
of dehydrated polyacrylamide (PAAm) gel has been measured
with a vibrometer at several frequencies.
The elastic stiffness (Young's modulus) showed marked changes
(significant decrease in the real part and a clear peak in the imaginary part)
around a characteristic temperature, which shifted toward the higher region
with increasing applied frequency, similar to the features
observed during the glass transition of noncrystalline polymers.
The activation energy of the elastic stiffness relaxation was also calculated
with the peak temperature of the imaginary part and the applied frequency.
The activation energy value of the dehydrated PAAm gel was in the range
usually observed for noncrystalline polymers,
based on which dehydrated PAAm gel has been confirmed to have the properties
usual for noncrystalline polymer glass from an elastic point of view.
Ultrasonic Velocity and Absorption Measurements for Polyethylene glycol and Water Solutions
Authors: Bae Jong-Rim , Kim Jeong-Koo , Yi Meyung-Ha
Published: October 2002

Ultrasonic velocity at 3 MHz using the pulse echo overlap method over the temperature range of 10–90°C and absorption coefficient over the frequency range of 0.2–2 MHz using the plano-concave resonator method at 30°C were measured in an aqueous solution of polyethylene glycol over the concentration range of 5% to 25% by weight. The velocity exhibited a maximum value at approximately 30°C, 40°C, 50°C, 60°C and 70°C in 25%, 20%, 15%, 10%, and 5% solutions, respectively. The velocity increased with concentration at a given temperature. The ultrasonic relaxation in polyethylene glycol aqueous solutions, which may be the result of structural fluctuations of polymer molecules such as the internal motion of the polymer chains, was observed, and the change of α/f2was greater at lower frequencies, especially below 0.5 MHz. The shear viscosity decreased with temperature and increased with concentration.
Effect of Ultrasound on Enhanced Permeability During Membrane Water Treatment
Authors: Kobayashi Takaomi , Kobayashi Tsuyoshi , Fujii Nobuyuki
Published: October 2002

Ultrasound of 28 kHz frequency in the range of 8–33 watt (W)
was used to study the effect of ultrasound on permeate flux of
peptone solution during ultrafiltration treatment of polysulfone
(PS) membrane. Ultrasound irradiation enhanced the permeation flux
through the membrane with increasing ultrasound power. The
correlation between ultrasound power and solute permeability
suggests that ultrasound was useful for cleaning membranes fouled by
rejected peptone layer.
A Multi-Transducer Near Field Acoustic Levitation System for Noncontact Transportation of Large-Sized Planar Objects
Authors: Takafumi Amano Takafumi Amano , Yoshikazu Koike Yoshikazu Koike , Kentaro Nakamura Kentaro Nakamura , Sadayuki Ueha Sadayuki Ueha , Yoshiki Hashimoto Yoshiki Hashimoto
Published: October 2002

A new noncontact transportation system, which consists of multiple ultrasonic transducers and operates based on near-field acoustic levitation, is proposed to transport a large-sized planar object such as a glass substrate for liquid crystal devices. Using the proposed systems consisting of two and three transducers, the suspension characteristics of the levitated objects are studied as functions of both size difference and angles between the vibration systems and the levitated object. As a result, the holding force is proved to increase as the angle increases and is maximum when the horizontal dimensions of the system and the object coincide.