bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Electrical Properties of Bi4Ti3O12 Ceramics by Spark Plasma Sintering
Authors: Takahashi Junichi , Kawano Syuichi , Shimada Shiro , Kageyama Keisuke
Published: October 2002

Spark plasma sintering (SPS) was applied to the production of non-lead ferroelectric
Bi4Ti3O12 ceramics. A powder compact of a calcined oxide mixture was embedded in a
mixture of ZrO2 and Sb-doped SnO2 powders in a carbon die and heated for a very short
duration under a constant current of 450 A. This process led to the rapid densification of
the sample with the simultaneous elongation and coarsening of grains in the sintered body.
When a coprecipitated precursor was used as the starting powder, a grain-oriented sample
was readily obtained by the SPS method. A strong anisotropy in electrical properties was
observed for the grain-oriented Bi4Ti3O12 ceramics.
High Power Characteristics of Piezoelectric Ceramics in Pb(Mn1/3Nb2/3)O3–PbTiO3–PbZrO3 System
Authors: Ise Osamu , Satoh Kaoru , Mamiya Yoichi
Published: October 2002

As one of high power characteristics of the piezoelectric
ceramics in Pb(Mn1/3Nb2/3)O3–PbTiO3–PbZrO3
system, the limit vibration velocity (v
max
), is defined as the
vibration velocity that generate the fixed temperature rise was
evaluated. From this system, a new material with a higher
v
max
of 0.79 m/s which is 1.7 times larger than conventional
Pb(Mn1/3Sb2/3)O3–PbTiO3–PbZrO3 system was
found. By using this new material, piezoelectric transformers were
made and the output electric power (P) of the transformers were
measured at R
L=(ω·C
d2)-1 [load resistance (R
L), resonant angular frequency (ω), output damping capacitance (C
d2)] and at other fixed resistances. The P of the piezoelectric transformer was measured on this condition, however, measured values of P were smaller than that of the conventional material. In order to clarify this phenomenon, an equivalent circuit including stray capacitance (C
f) of the load circuit was proposed.
Simulation results by using this equivalent circuit showed that;

1.  The load resistance giving the maximum output power decreases, as C
f increases.
2.  The maximum output power decreases, as C
f increases.
3.  When C
d2 of the piezoelectric transformer is small, the effect of C
f on the piezoelectric transformer becomes large.
Therefore, a high dielectric constant (ε) is a required characteristic
of the piezoelectric ceramic materials for use in the piezoelectric
transformer, except for the usually high v
max
and high
electromechanical coupling coefficient (K).
Temperature Dependence of Piezoelectric Constant of 0.5PbNi1/2Nb2/3O3–0.5Pb(Zr, Ti)O3 Ceramics in the Vicinity of Morphotropic Phase Boundary
Authors: Kondo Masao , Tsukada Mineharu , Kurihara Kazuaki
Published: October 2002

The temperature dependence of the piezoelectric constant of
PbNi1/2Nb2/3O3–PbTiO3–PbZrO3 50/x/50-x
ceramics (PNN–PT–PZ) in the vicinity of the morphotropic phase
boundary (MPB) induced with dc bias was investigated. The maximum
value of the transverse piezoelectric constant, d
31, of the
ceramic of PNN–PT–PZ 50/34/16 was 400 pm/V at room temperature and
600 pm/V at around 80°C. In the tetragonal ceramic of
PNN–PT–PZ 50/35/15, d
31 exhibited a maximum with increasing
temperature, and the position of MPB did not change under dc
bias. In the rhombohedral ceramics of PNN–PT–PZ 50/34/16 and
50/33/17, d
31 also exhibited a maximum with increasing
temperature, because the ceramics underwent a phase transition from
rhombohedral to tetragonal. These maximum positions of d
31 shift to
higher temperatures with increasing dc bias in the rhombohedral
ceramics only. Based on the relationship between d
31 and
temperature under bias, a phase diagram for
0.5PbNi1/2Nb2/3O3–0.5Pb(Zr, Ti)O3 ceramics under
dc bias is proposed. The ratio of the tilt of the MPB to temperature
under dc bias is smaller than that under no dc bias.
Influence of Media Surrounding Piezoelectric Ceramics on Current-Jump Phenomena
Authors: Ishii Keisuke , Yamada Takashi , Tashiro Shinjiro , Igarashi Hideji
Published: October 2002

The relationship between the viscosity of media and the current-jump phenomenon,
which appears in piezoelectric ceramics driven at high power levels, was studied. With
increasing viscosity of the medium, the magnitude of the current drop of the jump
phenomenon became smaller, and the driving voltage required for the current jump
increased. In order to elucidate the origin of the viscosity effects, we focused on the
apparent resonance resistance that increased under medium viscosity conditions. The
influence of apparent resonance resistance was theoretically discussed using the equation
introduced from the nonlinear piezoelectric equation. The theoretical values agree well
with the measured ones. The current-jump phenomenon hardly appears in high-viscosity
media because apparent resonance resistance of the sample increases with increasing
viscosity of the media.
Investigation of Ultrasonic Motors Using Thin Piezo-Ceramics and a Metal Composite-Plate for Watches
Authors: Miyazawa Osamu , Hashimoto Yasuharu , Funasaka Tsukasa , Furuhata Makoto
Published: October 2002

The authors have developed a 0.4-mm-thick longitudinal bar-type ultrasonic motor for
use in watches, using a thin plate stator and a rotor equipped within the same plane. The
stator is driven to vibrate length wise by piezo-ceramics oscillated in the first
longitudinal mode. The stator then uses a slant projection tooth to pick at the rotor, and
drive it. The motor is simply constructed and is easily driven at low voltages. This paper
shows that the ultrasonic motor possesses the requisite size and operating characteristics
for use in driving the date wheel of a watch.
Observation of Franz-Keldysh Oscillations in InP Self-Assembled Quantum Dot Systems
Authors: Shigeo Sugou Yasuaki Masumoto
Published: October 2002

Distinct Franz-Keldysh oscillations were observed in the nonlinear
reflection spectra of heterostructures with InP self-assembled quantum dots
measured by the pump-probe method. These oscillations
showed the presence of a built-in electric field of about 30 kV/cm. The
built-in electric
field is considered to originate from the electric charge captured by the
structural defects
on the dot interface. The estimated areal density of the electric charge is about
2×1011 cm-2.
Electroreflectance showed nonmonotonic changes with the change in applied
bias.
Growth of K3Li2-xNb5+xO15+2x Single-Crystal Fibers
Authors: Fujii Makoto Matsukura , Adachi Masatoshi
Published: October 2002

K3Li2-x
Nb5+x
O15+2x
(KLN) is
one of the most interesting materials for various applications
because of its excellent electrooptic, nonlinear optic and piezoelectric properties.
The growth of K3.0Li1.7Nb5.3O15.6 (KLN53: x=0.3) and K3.00Li1.85Nb5.15O15.3 (KLN51.5: x=0.15) single-crystal fibers
by the laser-heated pedestal growth (LHPG) method is reported.
Since KLN53 fibers were grown from the <110 > oriented seed crystal,
the fibers were oriented to the <110 > axis.
On the other hand, growth of KLN51.5 fibers grown from a ceramic rod as a seed
led to the <111 > oriented crystal.
The Curie temperature of the KLN53 fiber was measured.
The homogeneity of the fiber was investigated by measuring the Curie temperature.
Effects of V/III Ratio on the Properties of In1-xGaxP/GaAs Grown by a Valved Phosphorus Cracker Cell in Solid Source Molecular Beam Epitaxy
Authors: Yoon Soon Fatt , Mah Kia Woon , Zheng Hai Qun
Published: October 2002

We report the molecular beam epitaxial (MBE) growth of
high-quality In1-x
Ga
x
P epilayers grown on a GaAs (001)
substrate using a valved phosphorus cracker cell at a wide range of
V/III flux ratios. Film characterization was carried out using X-ray
diffraction (XRD), Raman scattering and low-temperature
photoluminescence (PL). A typical Raman spectrum showed features
characteristic of atomic disorder in the material with the
appearance of GaP-like and InP-like longitudinal-optic (LO) modes
and the transverse-optic (TO) mode. The PL peak energy increased
from 1.941 eV to 1.967 eV while the PL full-width at half maximum
(FWHM) decreased from ∼11.3 meV to ∼6.3 meV as the
V/III ratio was increased from 5 to 50. This suggests an increase in
the atomic disorder (more random) and improvement in the optical
quality. The Stokes shift, estimated from the energy difference
between the band-gap calculated using XRD composition and PL peak
energy, suggests an increase in microclustering following a
decrease in the V/III ratio.
Heterodyne-Detected Accumulated Photon-Echo Spectroscopy of CuCl Quantum Dots
Authors: Tsekhomskii Ryosuke Kuribayashi , Baranov Alexander V.
Published: October 2002

A heterodyne-detected accumulated photon-echo spectroscopy has been applied for the first time to the study of the excitonic dephasing dynamics in CuCl spherical quantum dots embedded in a glass matrix; this spectroscopy has the advantage that a hole-burning spectrum can be extracted from the Fourier-cosine transformation of the signal profile. Owing to this advantage, we reveal that an anomalously slow rise of the time-integrated echo signal at low temperatures, which was also observed in the previous ordinary photon-echo spectroscopy but the origin was left unknown, is caused by a spectral antihole. From the decay (single exponential one) part of the signal which is found to be not influenced by this anomaly, we have obtained rich unambiguous information about the dephasing time T
2 such as the temperature dependence, which is found to be essentially the same as the previous one that one might cast some doubt on.
Effects of Etch-Induced Damage and Contamination on the Physical and Electrical Properties of Cobalt Silicides
Authors: Hyeon-Soo Kim Hyeon-Soo Kim , Jong-Ku Yoon Jong-Ku Yoon , Young-Hyuk Lee Young-Hyuk Lee , Young-Wook Ko Young-Wook Ko , Jong-Wan Park Jong-Wan Park , Geun-Young Yeom Geun-Young Yeom
Published: October 2002

Damage and residue remaining on the silicon wafer after oxide overetching using C4F8/H2 plasmas and the effects of various post treatments after the overetching on the formation of contact silicides were investigated. The Co silicides formed on the variously etched surfaces were unstable, therefore, the sheet resistances were high and dependent on the etching conditions. However, stable Co silicides could be formed on the etched silicon surfaces regardless of etch conditions after O2 plasma cleaning followed by thermal annealing at 600°C and the sheet resistance and the thickness of the silicides were close to those of the silicides formed on a clean control silicon surface. The formation of stable Co silicides was more dependent on the characteristics of the residue than on the damage remaining on the silicon surface. The effects of the remanent residue and damage on the formation of stable silicides following Ti silicidation were similar to those following Co silicidation.
Output Enhancement Effect of Magnetic Underlayer in High-Density Magnetic Recording
Authors: Endo Katsumi , Yoshida Osamu , Sasaki Kenji , Nakayama Kazuhiko , Maki Kazuo , Nakamura Yoshihisa
Published: October 2002

A double-layered tape with a metal particulate (MP) upper layer and a metal-evaporated (ME) underlayer is fabricated. Output properties were enhanced over the single-layered MP tape in high-density recording. This effect cannot be explained by conventional magnetic recording mechanisms, and a new model of magneto-static interaction is proposed. This model is supported by a preliminary computer simulation.
Magnetic, Optical and Microwave Properties of Rare-Earth-Substituted Fibrous Yttrium Iron Garnet Single Crystals Grown by Floating Zone Method
Authors: Sekijima Takenori , Kishimoto Hiroshi , Fujii Takashi , Wakino Kikuo , Okada Masakatsu
Published: October 2002

We studied the crystallographic, magnetic, optical and microwave propagation properties of fibrous rare-earth-substituted Y2.7R0.3Fe5O12 (R:YIG) single crystals, grown by a simple floating
zone (FZ) method with yttrium aluminium garnet (YAG) laser heating assisted by infrared
irradiation, for all rare-earth elements. The first purpose of our studies was to seek outstanding
properties of R:YIG crystals and the second aim was to obtain data in order to develop crystals with
complex properties, such as large Faraday rotation and low saturation magnetization, by
substituting two or more rare-earth elements for Y into the YIG crystal. The lattice constant,
saturation magnetization, Faraday rotation, optical absorption coefficient, full-width at half
aximum (ΔH) of ferromagnetic resonance and microwave propagation in magnetostatic wave (MSW) modes were measured for R:YIG single crystals. Low saturation magnetization in Gd:YIG and Tb:YIG, large Faraday rotation in Ce:YIG and low loss propagation of MSW in Lu:YIG were
found. Our comprehensive results will also contribute to identifying
new materials applicable in for optical and microwave devices
utilizing R:YIG crystals.
Coercivity Mechanism and Microstructure Study of Sputtered Nd–Fe–B/X/Si(111) (X=W, Pt) Films
Authors: Tsai Jai-Lin , Chin Tsung-Shune , Chen Shi-Kun
Published: October 2002

Nd–Fe–B films on Si(111) were prepared by DC magnetron sputtering with W or
Pt underlayer. Coercivity analysis of films was realized by fitting phenomenological
model and Kronmüller formulation of micromagnetic model. For the
phenomenological model that determined by overcoming energy barrier and thermal
activation behavior, geometry effect of reversed domain and disturbance of domain-wall energy play important roles. The form factor α can be estimated equal to 1.08,
0.76 for W, Pt underlayer, respectively, by considering geometry and reduced domain-wall energy. For the Kronmüller model, coercivity was taken as a function of effective
nucleation field determined by the misalignment of grains and surface inhomogeneity
range where the reversed domain nucleates preferentially. Nd–Fe–B films with W
underlayer show a nucleation type mechanism with surface inhomogeneity
range αK= 0.32. However, Nd–Fe–B films with Pt underlayer show mainly domain-wall pinning
behavior with a range factor r
0 equal to 0.64 nm as r
0<δB (δB: the domain-wall width),
and 14.9 nm as r
0> δB.
Monte Carlo Modeling of Electron Transport and Capture Processes in AlGaAs/GaAs Multiple Quantum Well Infrared Photodetectors
Authors: Maxim Ryzhii Maxim Ryzhii , Victor Ryzhii Victor Ryzhii
Published: October 2002

The results of an ensemble Monte Carlo (MC) particle modeling of vertical electron transport and capture processes in AlGaAs/GaAs multiple quantum well infrared photodetectors (QWIPs) are presented. The MC model employed takes into account features of the conduction band structure, the electron scattering parameters, and the interaction (reflection, transmission and capture) of free electrons with the QWs. It is shown that the heating of free electrons and their redistribution over the conduction band valleys under the influence of electric field play an essential role in both the transport processes and the capture into bound states in the QWs. The electron drift velocity and macroscopic capture parameter are calculated as functions of the structural parameters and applied electric field. The capture parameter exhibits a pronounced drop with increasing electric field due to a significant decrease of the fraction of electrons with energies less than the optical phonon energy.
Surface Pretilt Effects of Bistable Twisted Nematic Liquid Crystal Display
Authors: Yoo Jeong-Geun , Song Byoung-Sang , Kim Joonki
Published: October 2002

Electrooptical properties of a bistable twisted nematic liquid crystal display are
studied as a factor of surface pretilt angle. It is shown experimentally that the selection
voltage decreased and the maximum transmittance increased as the surface pretilt angle
is increased. These effects can be explained by the backflow effect
and the stabilities of 0° and 360° twisted states upon changing the surface
pretilt angle.
Fabrication of Optical Wave-Guides in Silica-on-Silicon by Nickel Electroplating and Conventional Reactive Ion Etching
Authors: Massimi Anna , Fabrizio Enzo Di , Gentili Massimo , Piccinin Davide , Martinelli Mario
Published: October 2002

A novel process for the fabrication of deep optical waveguides in silica-on-silicon for optical processing applications has been developed. It makes use of nickel electroplating to conform precisely e-beam written smooth curved structures and to use the deposited nickel to etch deeply (up to 8 µm) into silica layers. It is demonstrated that nickel plating offers substantial advantages in terms of resistance and resist mold fidelity than more conventional etch masks such as patterned metal layers. The etching process, that is based on conventional fluorine reactive ion etching, has been optimized by making use of a design of experiment technique, details of process optimization and comparative analysis of different etching mask performances are also given.
Ultrasonic Joining of Si3N4 Plates at 19 kHz Using Al, Cu and Ni Plates as Insert Metal
Authors: Okamura Naoyuki , Watanabe Yuji
Published: October 2002

Ultrasonic joining of ceramic plates using the lateral face of a rod vibrating longitudinally at 19 kHz was studied. We joined two 2-mm-thick silicon nitride (Si3N4) plates with an insert metal plate sandwiched between the Si3N4 plates. The insert metal has a high melting point so that the joint is resistant to high temperatures. The insert metals that we used were Al, Cu and Ni. The joining tool was a straight bar vibrating longitudinally at 19 kHz. The lateral face of the bar was vigorously rubbed against the ceramic plate and the resultant increase in temperature was high enough to enable joining of the plates. The joining, which was acomplished in 3–5 s, was performed without any surface pretreatment.
Measurement of Nonsymmetrical Electric Field Vector Distribution in Nitrobenzene Using Electrooptic Method
Authors: Haruo Ihori Haruo Ihori , Masaharu Fujii Masaharu Fujii , Kiyomitsu Arii Kiyomitsu Arii
Published: October 2002

The three-dimensional nonuniform electric field vector distribution was measured in a nonsymmetrical electrode system using the Kerr electrooptic effect with the reconstruction technique modified by computed tomography (CT). The intensity of the light transmitted through a dielectric liquid in nonuniform field was detected at many points on one plane. It was found that the nonuniform electric field in the liquid can be measured three-dimensionally and visualized.
Experimental Measurement of the Intensity Profiles of a Low-energy Electron Beam Extracted from a Scanning Tunneling Microscope Tip by Field Emission
Authors: Ippei Kawamoto Ippei Kawamoto , Nan Li Nan Li , Tatsuo Yoshinobu Tatsuo Yoshinobu , Hiroshi Iwasaki Hiroshi Iwasaki
Published: October 2002

The intensity profile of a low-energy electron beam (e-beam) extracted from the tip apex of a scanning tunneling microscope (STM) in the field emission mode was measured in an ultrahigh-vacuum environment. The sizes of areas where the native Si oxide was removed by exposure to the low-energy e-beam were measured as a function of the e-beam exposure time, and it was found that the e-beam has a Gaussian-type lateral profile. The results show that the e-beam profile can be controlled by adjusting the parameters of the e-beam emission and that the sizes of the Si oxide opening windows can be adjusted by varying the e-beam exposure time.
Molecular Beam Epitaxy of GaN under N-rich Conditions using NH3
Authors: Grandjean N. , Leroux M. , Massies J. , Mesrine M. , Laügt M.
Published: October 2002

Ammonia has been used to grow GaN layers by molecular beam epitaxy on c-plane
sapphire substrates. The ratio of nitrogen to Ga active species, i.e., the actual V/III ratio,
has been varied from 1 to 4. It is found that increasing the V/III ratio improves the
material properties both in terms of optoelectronic and structural quality. This is
demonstrated by photoluminescence (PL) experiments, Hall measurements, secondary
ion mass spectroscopy (SIMS), and atomic force microscopy. The origin of the residual
n-type doping of undoped GaN layers is also discussed on the basis of SIMS and PL results.
Inhomogeneous Broadening of Zeeman Absorption Peak of Shallow Donor in Semi-Insulating GaAs
Authors: Fujii Ken-ichi , Hosokawa Makoto , Ohyama Tyuzi
Published: October 2002

Magnetooptical absorption measurements of shallow donors in semi-insulating GaAs are carried out to investigate the roles of EL2 centers for the Zeeman absorption peak of shallow donors. The transition from a stable state to a metastable state of EL2 centers by infrared irradiation involves a photoquenching of EL2, which also induces a decrease of shallow donors. Photoquenching changes the role of EL2 as a compensator. The change of the compensation affects the linewidth of the absorption peak due to the Stark effect. In that effect, contributions from the transition and from ionization of EL2 are studied separately. Although the delay time variation of the absorption intensity of the peak after pulsed bandgap excitation is sensitive to photoquenching, the linewidth is almost independent of the transition. Ionization, however, causes broadening of the linewidth.
Full Multiple Scattering Approach to X-Ray Absorption near Edge Structure Spectra of Bromonaphthalene in Supercritical Xenon
Authors: Kuniko Hayakawa Kuniko Hayakawa , Kohji Kato Kohji Kato , Takashi Fujikawa Takashi Fujikawa , Takatoshi Murata Takatoshi Murata , Kazumichi Nakagawa Kazumichi Nakagawa
Published: October 2002

Detailed X-ray absorption near edge structure (XANES) analyses are carried out in order to study the local structure around a Br atom of bromonaphthalene dissolved in supercritical fluid Xe by usage of full multiple scattering calculations. We find that about six Xe atoms surround the Br atom at the distance of about 5 Å, which is larger than the sum of the van der Waals radii (4.15 Å). Other important information is the relative thermal fluctuation (Debye-Waller factor) between Br and Xe, which is quite large, ∼0.8 Å. This large thermal fluctuation and clustering are essential characteristic features of supercritical systems.
Bilayer SiNX/Diamond Films for X-Ray Lithography Mask
Authors: Huang Bohr-Ran , Sheu Jeng-Tzong , Wu Chia-Haur
Published: October 2002

In this research, an alternative fabrication process is proposed
for SiN
X
/diamond and diamond membranes. After diamond film
deposition, SiN
X
films were coated on both sides of the diamond
film using the low-pressure chemical vapor deposition (LPCVD)
process. The back side of the SiN
X
film was selectively etched
using the reactive ion etching (RIE) technique. The SiN
X
/diamond
membrane was then obtained by etching the back side of the silicon
wafer with KOH solution. The diamond membrane was finally achieved by
etching the front side of the SiN
X
film. It was found that the
concentration of methane affects the quality, film stress and surface
roughness of
polycrystalline diamond films. These properties also influence the
optical transmittance of the membranes. Typically, it was found that
bilayer SiN
X
/diamond membranes exhibited a higher optical
transmittance than diamond membranes. It was also shown that samples
with lower methane content (1.5%) possessed higher optical
transmittance than those with higher methane content (2%). The
optical transmittance of the S1(1.5%) bilayer SiN
X
/diamond
membrane was about 57% at a wavelength of 633nm and up to 66% at a
wavelength of 800 nm. The optical transmittance of the bilayer
SiN
X
/diamond and diamond membranes increased by approximately 7%
and 5% for S1(1.5%) since the quality of the diamond films improved
after X-ray irradiation.
Noise Performance of Pseudomorphic AlGaAs/InGaAs/GaAs High Electron Mobility Transistors with Wide Head T-Shaped Gate Recessed by Electron Cyclotron Resonance Plasma Etching
Authors: Lee Jin-Hee , Yoon Hyung-Sup , Meang Byung-SunPark , Lee Chul-Wook , Choi Hyun-Tae , Yun Chan-Eui , Park Chul-Soon
Published: October 2002

Passivated 0.15 µm pseudomorphic high electron mobility
transistors (PHEMTs) were fabricated by combining a wide head T-shaped
gate, formed using a dose split method of electron beam lithography,
with a short source-gate separation, using formed an electron
cyclotron resonance dry recess etching process. The threshold voltage
of the devices showed 50 mV variation across three-inch wafers. The
extrinsic transconductance and cutoff frequency of the PHEMT devices
were 688 mS/mm and 82.6 GHz, respectively. The lowest minimum noise
figure, NF
min, of the PHEMT devices was observed
around 80% of the saturation drain current at 30 GHz and
V
ds = 2 V. The devices exhibited a
NF
min as low as 0.99 dB with an associated gain
of 9.1 dB at 30 GHz. This noise figure value is the lowest data ever
reported for a PHEMT device using a dry recess process.
Image Conservation in Inelastically Scattered Electrons in Reflection Electron Microscopy
Authors: Tanishiro Yasumasa , Okamoto Kimiharu , Suzuki Takayuki , Ishiguro Nami , Mimoda Hiroki , Miura Hidetoshi , Yagi Katsumichi , Takeguchi Masaki
Published: October 2002

Energy-filtered reflection electron microscope (REM) images of well-defined surfaces were taken for the first time using an ultrahigh vacuum electron microscope equipped with an omega filter. Si(111)7×7 and Si(111)5×2-Au surfaces were imaged. Images using electrons with energy losses of 11.3 and 22.6 eV (single and double surface plasmon excitation) showed lattice fringes of Si(111)7×7(2.3 nm in spacing) and Si(111) 5×2-Au(1.7 nm). The observation gave the first experimental evidence that diffraction image contrast is conserved in images formed by electrons inelastically scattered by small angles in REM, as in the case of transmission electron microscopy.
Influence of Gas Desorption from SiOF Film Prepared by High-Density-Plasma Chemical Vapor Deposition upon TiN/Ti Film
Authors: Tamura Takahiro , Sakai Junro , Satoh Makoto
Published: October 2002

The influence of gas desorption from fluorine-doped silicon oxide (SiOF) film prepared by high-density-plasma chemical vapor deposition (CVD) upon
TiN/Ti film is investigated. In this investigation, two types of SiOF films,
containing 14% and 6% fluorine atoms, are compared with regard to gas
desorption and diffusion of fluorine, hydrogen and oxygen atoms into TiN/Ti film
on SiOF film, as-deposited on TiN/Ti/SiOF film and after 400°C annealing. In
addition, W film was prepared on TiN/Ti/SiOF film in order to examine the
practical effect of gas desorption upon adhesion between Ti film and SiOF film.
Thermal desorption mass spectroscopy (TDS) and secondary-ion mass
spectroscopy (SIMS) spectral studies clarified the following. (1) SiOF film
containing 14% fluorine atoms has a high hydrogen-fluoride content due to
moisture absorption after exposure to air, while that containing 6% fluorine atoms does not. (2) During deposition of TiN/Ti film at 200°C, many fluorine and
hydrogen atoms diffuse from SiOF film containing 14% fluorine atoms and are
trapped within the Ti film or the Ti/SiOF interface. (3) During 400°C annealing,
more fluorine atoms diffuse from SiOF film containing 14% fluorine
atoms and are also trapped within the Ti film. (4) Fluorine atoms
trapped within the Ti film degrade the adhesion between Ti film and
SiOF film.
Surface and Bulk Passivation effect of GaAs grown on Si Substrates by SeS2Treatment
Authors: Arokiaraj Jesudoss , Soga Tetsuo , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

The effect of selenium sulphide (SeS2) treatment for GaAs grown
on Si has been studied. The surface and bulk properties such as the
photoluminscence intensity and minority carrier life-time have been
significantly increased. The PL intensity showed a two fold and four
fold increase for the as-passivated, passivated and annealed
samples. It is proposed that the passivation on the surface occurs by
means of sulphur and selenium atoms. The bulk passivation is by means
of diffusion of Se into the bulk of the epilayer. Additional steps of
annealing increased the minority carrier life time thereby reducing
the recombination velocity and also indiffusion of Se helps to
passivate the buried defects such as AsGa in the double
heterostructures. Results obtained by X-ray photoelectron spectroscopy (XPS) reveal that sulfides and
selenides reside on the outermost surface and only gallium based
selenides are in the bulk of the GaAs layer.
Phase-locked Timing Extraction from 40 Gbps Optical Signal using Harmonically Mode-locked Er-doped Fiber Ring Laser
Authors: Kim Dong Hwan , Kim Sang Hyuck , Jo Jae Cheol , Choi Sang Sam
Published: October 2002

A prescaled 10 GHz clock recovery from a 40 Gbps time-division-multiplexed (TDM) optical signal has been demonstrated with a low-frequency-oscillator-free phase-locked loop (PLL) circuit based on four-wave-mixing in a semiconductor optical amplifier. 40 GHz optical PLL using a 10 GHz mode-locked fiber ring laser as a clock pulse was stable over 5 h within 10 KHz lock-in frequency detuning of 40 GHz TDM optical signal.
Refractive Index Changes of Doped Polymer Films Induced by the Photoelimination of Meso-Ionic Heterocyclic Compounds with and without a Sulfur Atom
Authors: Murase Seiichiro , Ban Masaki , Horie Kazuyuki
Published: October 2002

We measured refractive index changes of doped polymer films
induced by photoelimination of meso-ionic heterocyclic compounds. A
poly(methyl methacrylate) (PMMA) film containing 30 wt%
3-phenyl-1,2,3,4-oxatriazole-5-thione (3POTT) showed a large
refractive index change of -0.02 during photoirradiation, at a
wavelength far from the resonant region. PMMA films containing
meso-ionic compounds with a sulfur atom in the meso-ionic ring showed
large refractive index changes during photoirradiation, while PMMA
films containing 3-phenyl-1,2,3,4-oxatriazole-5-one, which possess no
sulfur atoms in the meso-ionic ring, showed relatively small changes
in refractive index. This difference may be due to the existence of a
sulfur atom in the meso-ionic ring. We estimated the specific
refractions of the eliminating groups, and we found that both the
existence of a sulfur atom and the position of the sulfur atom in the
meso-ionic group affect the specific refractions.
Improvement of Quality Value and Shift of τf Value of BiNbO4 Ceramics with Addition of CuO–V2O5 Mixtures
Authors: Yang Cheng-Fu
Published: October 2002

Undoped BiNbO4 ceramics cannot be densified even at a
sintering temperature of 960°C. However, BiNbO4 ceramics
can be densified at 900–920°C when different
CuO–V2O5 mixtures of 0.5 wt% are used as sintering
aids. The dielectric properties of BiNbO4 ceramics sintered at
920°C were compared, and it was found that the dielectric
constants almost unchanged, regardless of the CuO–V2O5
mixture added. As the V2O5/CuO ratio increases, the quality
value (Q) increases and the temperature coefficient of resonant
frequency (τf) changes from a negative value to a
positive one. The Q and τf values of BiNbO4
ceramics are 1620 and -20.8 ppm/°C when 0.5 wt% CuO is
added, while they are 3410 and 13.8 ppm/°C when 0.5 wt%
V2O5 is added. BiNbO4 ceramics with 0.25 wt%
CuO–0.25 wt% V2O5 and 0.1 wt% CuO–0.4 wt%
V2O5 have high Q values of 3060 and 3310 and low
τf values of -7.8 and +6.8 ppm/°C,
respectively.
Preparation and Electrical Properties of Rhombohedral Pb(ZrxTi1-x)O3 Thin Films by RF Magnetron Sputtering Method
Authors: Wensheng Wang Wensheng Wang , Tadashi Fujii Tadashi Fujii , Tomoaki Karaki Tomoaki Karaki , Masatoshi Adachi Masatoshi Adachi
Published: October 2002

Rhombohedral lead zirconate titanate (PZT) thin films with a thickness of 0.3–1.2 µm were successfully grown on (111)Pb(La,Ti)O3/Pt/Ti/SiO2/Si and (111)Ir/SiO2/Si substrates by an RF magnetron sputtering method using a multi-target consisting of calcinated PbO and metal titanium pellets on a zirconium metal plate. The composition of the films could be controlled by adjusting the area ratio of PbO/Zr/Ti. The crystal structures of the films were sensitive to the area of PbO and the substrate temperature. The pyroelectric current, relative dielectric constant, Curie temperature, remanent polarization (P
r) and coercive field dependence on the Zr content of the films are described. The pyroelectric coefficient of the as-prepared PZT films showed a peak from 94°C [for Pb(Zr0.91Ti0.09)O3] to 36°C [for Pb(Zr0.97Ti0.03)O3], which corresponded to the phase transition from the low-temperature to high-temperature rhombohedral ferroelectric phase. The fatigue characteristic was also measured using a double bipolar pulse. The PZT films preserved an initial switching charge value over a switching cycle of 1012.
Complete Deep-Submicron Metal-Oxide-Semiconductor Field-Effect-Transistor Drain Current Model Including Quantum Mechanical Effects
Authors: Jang Sheng-Lyang , Chyau Chwan-Gwo , Sheu Chorng-Jye
Published: October 2002

In this paper, we present a new complete drain current model for
metal-oxide-semiconductor field-effect-transistor devices with very thin gate
oxide thickness and short-channel length. The model was developed using the
drift-diffusion equation and the quasi-two-dimensional Poisson equation. The
effects of the inversion layer centroid due to the quantum mechanical effect
and the drain-induced-barrier-lowering due to short-channel length are taken
into account in this model. The accuracy of this model has been checked by the
experimental data of thin gate-oxide and short-channel devices.
Application of Large-Scale Binary Optical Elements to High-Resolution Projection Optics Used for Microlithography
Authors: Unno Yasuyuki , Sekine Yoshiyuki , Murakami Eiichi , Ohta Masakatsu , Hirose Ryusho
Published: October 2002

The feasibility of applying binary optical elements (BOEs) to stepper projection optics
has been investigated. To obtain a large-scale element with high precision, a novel pattern
stitching technique is introduced into fabrication processes which use a stepper for pattern
exposures. The influence of mask alignment errors is theoretically studied to confirm that BOEs
fabricated with current lithographic tools show sufficiently high performance to be used as
stepper lens elements. The influence of uneven transmittance through BOEs and the behavior of
spurious order diffraction beams are also examined to estimate the imaging performance
degradation caused by inserting such an element into a projection lens. Then, we fabricate a
BOE with an effective diameter of 120 mm, and build a projection lens which has a numerical
aperture of 0.475 and operates with an exposure wavelength of 248.2 nm. As a result, a pattern
size of 0.22 µm is successfully delineated with an 0.8 µm depth of focus, which is comparative
to the performance of all-refractive lenses with the same
specifications.
High-Precision Binary Optical Element Fabricated by Novel Self-Aligned Process
Authors: Tanaka Ichiro , Iwasaki Yuichi , Ogusu Makoto , Tamamori Kenji , Sekine Yoshiyuki , Matsumoto Takahiro , Maehara Hiroshi , Hirose Ryusho
Published: October 2002

In the conventional procedure for fabricating binary optical elements (BOEs), we
ascertained, by optical simulation, that the alignment error is a principal factor in
diffraction efficiency. To deal with this problem we have developed a novel self-aligned procedure, and we have fabricated BOEs with high diffraction efficiency. The
key point of the novel procedure is that every step of the element is determined by the
first Cr hard mask. To achieve this, we used a negative photoresist with back exposure.
We fabricated four-level BOEs, and the diffraction efficiency of the BOEs is only 3%
below the theoretical value. Furthermore, we investigated the influence of the
remaining fabrication error in the novel method. The remaining error consists of the
etching depth error and critical dimension (CD) error. According to the optical
simulation, the CD error negligibly affects the diffraction efficiency. The only factor
we should consider is the etching depth error.
Sub-100 nm Lithography with KrF Exposure Using Multiple Development Method
Authors: Asano Masafumi
Published: October 2002

In this paper, a novel resist process technique using a chemically amplified resist with a
multiple development method for improving photolithography resolution is described. By
means of this technique, resist lines are formed at the edge position between the bright and
dark fields of a photomask, and the repeating frequency that is more than the cutoff frequency
of optics (ν
c
=1/P

c
=2NA/λ) can be delineated using a conventional exposure system. In the
experiment, a grating resist pattern with a pitch of 200 nm was obtained using a conventional
0.6 NA KrF exposure system and a 400 nm pitch photomask pattern. The pitch was less than
the diffraction limit of 207 nm (=0.5λ/NA) in the optical system used, which cannot be
realized by a conventional resist process even with resolution enhancement techniques such as
off-axis illumination and phase-shifting mask.
Sub-0.10 µm Hole Fabrication Using Bilayer Silylation Process for 193 nm Lithography
Authors: Satou Isao , Kuhara Kouichi , Endo Masataka , Morimoto Hiroaki
Published: October 2002

As the device design rule has been significantly reduced, a
practical pattern fabrication technique for sub-0.10 µm or
smaller dimensions is required. However, it is difficult to
fabricate hole patterns that are 0.10 µm or smaller in size,
and to maintain a sufficient process window. We found that in the
case of the bilayer silylation process using a thin negative working
resist as the top silylation layer, the depth of the silylated area
was simply determined by the silylation resist thickness. The
silylation reactions for an unexposed area were well controlled, and
the silylation reactions in the horizontal direction proceeded with
size-biasing of the width of the silylated area. After the
size-biasing process, the sub-0.10 µm hole patterns were
generated in the bottom novolac (NVC) layer by the dry development
process. Moreover, we confirmed the transfer of sub-0.10 µm
hole patterns into the 1.2-µm-thick SiO2 layer without the
use of any hard masks for dry etching.
Optimum Phase Condition for Low-Contrast X-Ray Masks
Authors: Fujii Kiyoshi , Suzuki Katsumi , Matsui Yasuji
Published: October 2002

A low-contrast X-ray mask works as an attenuating phase-shift
mask. The X-rays which pass through the clear and opaque areas of
the mask interfere with each other and therefore enhance the image
contrast. In proximity X-ray lithography, the rays which gather on
an image plane have a phase difference caused by the optical path
length. Thus, the phase shift (PS) on the wafer is determined by the
sum of the PS caused by the absorber and the PS caused by the
optical path length difference. In line-and-space (L&S) patterns,
the phase-shift effect can be simplified by considering two typical
rays: the rays passing through the center of the opaque area and
those passing through the center of the clear area. With this model,
the optimum phase condition is obtained by setting both the absorber
PS and the geometric PS as π/2. The 70 nm and 50 nm L&S
patterns are resolved under this condition.
Detection of Metastable Chlorine Ions in Time-Modulated Plasma by Time Resolved Laser-Induced Fluorescence
Authors: Shinya Kumagai Shinya Kumagai , Minoru Sasaki Minoru Sasaki , Mitsumasa Koyanagi Mitsumasa Koyanagi , Kazuhiro Hane Kazuhiro Hane
Published: October 2002

Metastable chlorine ions (Cl+*) were detected in time-modulated
inductively coupled plasma by
a time-resolved laser-induced fluorescence technique.
By varying the rf power, gas pressure and modulation
frequency, the Cl+* density was measured in detail.
In the discharge-on period, the Cl+* density increased
as the rf power increased.
In the discharge-off period, the rf power decreased within 1 µs,
however, the Cl+* density decreased more slowly and persisted for a while.
The decay constant was evaluated to be around 10 µs
by fitting the decay curve under our experimental conditions.
In addition,
the diffusion coefficient of Cl+* was also estimated.
Voltage Contrast Defect Inspection of Contacts and Vias for Deep Quarter Micron Devices
Authors: Yamazaki Yuichiro , Hayashi Hiroyuki , Miyoshi Motosuke
Published: October 2002

Electron beam induced voltage contrast of vias and contacts was
investigated for voltage contrast defect inspection. The
investigation was carried out on the basis of signal intensity
analysis of the voltage contrast image in relation to wafer bias and
charge density of the incident electron beam. It was determined
that voltage contrast is dependent on the balance between the
surface potential of the oxide surface due to charge-up and the
surface potential of vias and contacts. By adjusting the parameters
of the charge density and the wafer bias, the optimum conditions can
be obtained. Using this technique, the inspection of a 0.25 µm
logic and 0.18 µm dynamic random access memory (DRAM)
production wafer was carried out. The potential for inspecting
electric anomalous failures of a 0.18-µm-design-rule device,
which are difficult to detect by conventional optical inspection
tools, was confirmed.
Dynamic Simulation of Electron-Beam-Induced Chargingup of Insulators
Authors: Kotera Masatoshi , Yamaguchi Kiyoshi , Suga Hiroshi
Published: October 2002

The time-dependent charging process of an insulating specimen
under electron beam irradiation is calculated by taking into account
the charge continuity equation, the Poisson equation, Ohm's law and
the electron-beam-induced conductivity. The energy and the
charge deposition distributions are calculated by the Monte Carlo
simulation of electron trajectories taking into account the electric
field distribution in the specimen. The time-dependent charge and
potential distributions are obtained in the present
calculation. As the electron beam energy is 10 keV and the specimen
is a 1-mm-thick poly-methyl-methacrylate
(PMMA) wafer, the surface potential increases to a positive value at
first, and then becomes
a negative one. This charging process agrees with experimental
findings.
Microfabricated Dynamic Scanning Force Microscope Using a Three Dimensional Piezoelectric T-shape Actuator
Authors: Chu Jiaru , Maeda Ryutaro , Itoh Toshihiro , Kataoka Kenichi , Suga Tadatomo
Published: October 2002

A microfabricated dynamic scanning force microscope (DSFM) system
integrated with a self-exciting piezoelectric force sensor and position
actuators for three dimensions is presented. It is a cantilever-bridge
structure composed of two PZT (lead titanate zirconate) layers. The
electrodes of the levers are each divided into two sections. Electric
fields applied to the separated sections can induce lever deflection
and actuate the tip in the x, y, and z directions. The cantilever
can vibrate in the z direction and sense the deflection by its self
to detect the surface topography in the cyclic contact mode. The
microscopy sensitivity in the vertical direction is measured as 0.32 nA/nm,
with actuation rates of 83 nm/±V and 73 nm/±V
in X and Y directions, respectively.
Fabrication of Micromechanical Tunneling Probes and Actuators on a Silicon Chip
Authors: Toshiyoshi Hiroshi , Goto Masahide , Mita Makoto , Fujita Hiroyuki , Kobayashi Dai , Hashiguchi Gen , Endo Junji , Wada Yasuo
Published: October 2002

Simultaneous visual control of tip position is indispensable for
in-situ observation of nanoscopic phenomena at the tunneling gap.
In this paper we propose a one-chip tunneling control device, which is
small enough to load on a standard sample holder of the transmission
electron microscope (TEM). Tunneling probes and micro actuators have been
successfully integrated on a 2.4×2.4-mm2-chip by silicon
micromachining technique. A pair of sharp silicon tips is obtained by the
combination of stress-induced oxidation and selective etching of silicon
oxide. Typical dimensions of the tips are 10 nm in radius and 1 µm
in length with a 200-nm-initial gap. An electrostatically operated
comb-drive actuator is used to close the gap with a voltage around 100 V.
The tunneling tips are suspended over a through hole in the base
substrate, and the tunneling gap can be observed by TEM. We found that
clear images could be obtained without distortion or shift due to the
driving voltage applied to the integrated actuator.
Pulsed Laser Deposition of Diamond-Like Carbon Films on Gated Si Field Emitter Arrays for Improved Electron Emission
Authors: Yavas Oguz , Hashimoto Takeshi , Suzuki Naoki , Takai Mikio , Kobayashi Yohei Higuchi Michihiro , Hosono Akihiko , Okuda Soichiro
Published: October 2002

Diamond-like carbon (DLC) films were deposited on niobium gated silicon field emitter arrays to improve the emission properties.
DLC deposition was carried out either ex-situ by con-ventional pulsed laser deposition in a separate chamber or in-situ
during electron emission in a test chamber. Various process parameters such as the thickness of the DLC films and the ambient
gas during film deposition were systematically varied. The thickness of the DLC coating was found to play a crucial role for the
emission characteristics of the FEA. An increase of both the emission current and its stability could be achieved using thin
DLC films up to 6 nm. Thicker films, on the other hand, caused a decrease in the emission current. The results could be explained
by a metal-insulator-metal (MIM) model for the electron transport through the DLC film. An increase or decrease of the emission
current was observed also for the in-situ deposited DLC films depending on the gas environment during the deposition process.
Exchange Coupling in (Mn–Ir, Fe–Mn)/Co/Ni–Fe Multilayers
Authors: Nakatani Ryoichi , Hoshiya Hiroyuki , Hoshino Katsumi , Sugita Yutaka
Published: October 2002

We investigated the exchange coupling between antiferromagnetic layers and magnetic layers in Hf/(Mn–22 at.%Ir, Fe–40 at.%Mn)/Co/Ni–20 at.%Fe/Hf/Si multilayers. Insertion of Co layers between the antiferromagnetic layers and the Ni–Fe layers increased the exchange coupling for the Mn–Ir layers, but did not increase that for the Fe–Mn layers.
Characteristic Distributions of Narrow Channel Metal-Oxide-Semiconductor Field-Effect Transistor Memories with Silicon Nanocrystal Floating Gates
Authors: Eiji Nagata Eiji Nagata , Nobuyoshi Takahashi Nobuyoshi Takahashi , Yuri Yasuda Yuri Yasuda , Takashi Inukai Takashi Inukai , Hiroki Ishikuro Hiroki Ishikuro , Toshiro Hiramoto Toshiro Hiramoto
Published: October 2002

We report the width and length dependences of threshold voltage
shift and its distribution in narrow channel
metal-oxide-semiconductor field-effect transistor (MOSFET) memories
based on self-assembling silicon nanocrystals. As the channel width
decreases, the threshold voltage shift, along with its distribution,
increases. On the other hand, as the channel length decreases,
the threshold voltage shift decreases. These results are well
explained by the random distribution of silicon nanocrystals, in
particular the number of dots on the narrow channel. The difference
in width and length dependences is due to the difference in parallel
and serial connections of unit cells. Based on the unit cell model,
the width and length dependences of the threshold voltage shift are
calculated and compared with the experimental results.
Nano-Structure Fabrication and Manipulation by the Cantilever Oscillation of an Atomic Force Microscope
Authors: Kyeong Hyon Chan , Chul Choi Seung , Woo Hwang Sung , Kyu Kim Doyeol Ahn
Published: October 2002

Nanometer scale mechanical processing of semi-insulating GaAs surface was performed using a cantilever oscillating atomic force microscope. Oscillating probe tips induce bond breaking of the GaAs surface and generate nano-meter size patterns. The size of the pattern is shown to be fully controlled by the amplitude and the frequency of the external modulation voltage to the piezo-scanner.