bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Surface Energy States in Polyimide Langmuir-Blodgett Tunneling Barrier
Authors: Kubota Tohru , Kuragasaki Shinichi , Iwamoto Mitsumasa
Published: October 2002

We fabricated Au/polyimide (PI)/Pb junctions with the number of deposited PI
Langmuir-Blodgett (LB) layers of 19–23 as tunneling barrier, and measured the current–voltage
(I–V) and dV/dI–V characteristics of these junctions. Then, we estimated the
distribution of the density of surface energy states in PI LB film. It was suggested that
electron accepting states exist at the interface. Integration of the density of the surface
energy states in PI LB film gave a value higher than 2×1024 m-3. This result supports the
conclusion of our previous study, which was obtained from surface potential
measurement.
A Novel Phase Behavior and Optical Properties in a (Two Nematics/Cholesteric) Liquid Crystal Composite System
Authors: Hwang Jenn Chiu , Liang Shi Chang , Liang Kung Heng
Published: October 2002

The phase behavior and optical properties of a liquid crystal (LC)
composite (induced smectic phase formed by mixing two nematic LCs and
one cholesteric LC) have been studied. The nematic liquid crystal 4-cyano-4′-pentyloxy biphenyl 5OCB with a strong polar terminal group was miscible
with the nematic liquid crystal 4-hexyloxyphenyl-4′-pentyl benzoate HPPB
having a weak polar terminal group. This binary mixture formed an induced smectic phase over a wide temperature range. The (induced smectic/cholesteric) ternary composite exhibited smectic A, cholesteric and blue
phases. A novel phase was observed at the cholesteric-smectic phase
transition region. The ternary system exhibited highly transparent and opaque
states in the smectic and cholesteric phases, respectively, without the electric
field.
Molecular Beam Epitaxy of SrTiO3 Films on Si(100)-2×1 with SrO Buffer Layer
Authors: Tatsuyama Toyokazu Tambo
Published: October 2002

Molecular beam epitaxy of SrTiO3 thin films on a Si(100)-2×1 surface has been studied using reflection high-energy electron diffraction (RHEED), an atomic force microscope (AFM) and X-ray diffraction (XRD) as a function of the thickness of the SrO buffer layer and growth temperature.
Epitaxial SrTiO3 films do not grow directly on Si(100).
Therefore, a SrO buffer layer was applied to grow SrTiO3 on Si(100).
It was found that the SrO layer with a thickness of 100 Å grown at 300 – 400°C in oxygen atmosphere of 5 ×10-8 Torr was sufficient to grow epitaxial SrTiO3 on Si(100).
Then SrTiO3 thin films with a thickness of 2000 Å were grown on the SrO(100Å)/Si surface at 400 – 700°C using codeposition of strontium and titanium in oxygen atmosphere of 8×10-8 Torr.
At 500°C, the best-quality SrTiO3(100) film grew parallel to Si(100), and numerous rectangular platelike crystals were observed on the surface in the AFM image. The crystallinity of the STO films was improved with increasing thickness of the SrO layer.
The epitaxial relation between SrTiO3 and SrO/Si(100)-2×1 is also discussed using the RHEED patterns which show streaks and spots.
The Effect of Growth Environment on the Morphological and Extended Defect Evolution in GaN Grown by Metalorganic Chemical Vapor Deposition
Authors: Fini P. , Wu X. , Tarsa E. J. , Golan Y. , Srikant V. , Keller S. , Denbaars S. P. , Speck J. S.
Published: October 2002

The evolution of morphology and associated extended defects in GaN thin films grown on sapphire by metalorganic chemical vapor deposition (MOCVD) are shown to depend strongly on the growth environment.
For the commonly used two-step growth process, a change in growth parameter such as reactor pressure influences the initial high temperature (HT) GaN growth mechanism. By means of transmission electron microscopy
(TEM), atomic force microscopy (AFM), and high resolution X-ray diffraction (HRXRD) measurements, it is shown that the initial density of HT islands on the nucleation layer (NL) and subsequently the threading
dislocation density in the HT GaN film may be directly controlled by tailoring the initial HT GaN growth conditions.
Sol–Gel Processing of Ferroelectric PbTiO3 and Pb(Zr0.5Ti0.5)O3 Thin Films
Authors: Kumar Viswanathan , Ohya Yutaka , Takahashi Yasutaka
Published: October 2002

Ferroelectric thin films of PbTiO3 and Pb(Zr0.5Ti0.5)O3 were
deposited using a sol–gel process from a highly stable
precursor solution derived from a unique and simple system
consisting of basic lead acetate, titanium and zirconium
butoxides. This new system simplifies the chemical processing
of precursor solutions of lead titanate -based materials. By
adjusting the concentration of the precursor solution and using
the dip-coating technique, homogeneous thin films of PbTiO3 and
Pb(Zr0.5Ti0.5)O3 were deposited onto glass, conducting glass and
single crystal MgO(100) and SrTiO3(100) substrates. The
thin-films were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). P-E hysteresis
of these films revealed their ferroelectric nature. The effect
of indium-tin-oxide (ITO) bottom electrode on the microstructure of PZT thin films
in the PZT/ITO/glass substrate structure is also reported.
Light Emission and Surface States Annealing on GaAs Metal Semiconductor Field-Effect Transistor
Authors: Sasaki Hajime , Abe Masayuki , Hayashi Kazuo , Fujioka Takashi , Mizuguchi Kiyoshi , Yea Byeongdeok , Osaki Tomoyuki , Sugahara Kazunori , Konishi Ryosuke
Published: October 2002

The annealing mechanism of surface states in the gallium arsenide metal semiconductor field-effect transistor (GaAs MESFET) is investigated by measuring the light-emission characteristics and excess gate currents generated by hot-carriers. Nonuniform light emission is observed when the Schottky junction is reverse biased, and the nonuniformity is increased with temperature. On the other hand, uniform and strong emission is observed under RF operation even when the device is biased with a deep pinch-off condition. The reverse and forward Schottky current caused by RF swing may not be a main emission mechanism under RF operation. Light emissions due to impact ionization and thermionic field emission are observed separately. The light intensity of the thermionic field emission has a weak temperature coefficient, while that of the impact ionization has a strong negative temperature coefficient. The decreasing rate of the surface states depends on the intensity and the distribution of the light emission during the operation.
Measurement of Differential Compton Scattering Cross Section of 661.6 keV γ-Rays from Compounds Containing Hydrogen, Carbon and Oxygen
Authors: Mamdouh Abdelrahman Mamdouh Abdelrahman , Nagih Kamel Nagih Kamel
Published: October 2002

Compton scattering cross sections of 661.6 keV γ rays of 137Cs from
Al and 12 compounds containing hydrogen and carbon or hydrogen, carbon and
oxygen have been measured at three different scattering angles of
60°, 90° and 115°.
Differential Compton scattering cross section values for Al have been
obtained theoretically by means of incoherent scattering function calculation.
Comparing the experimental data with the theoretical cross section values for
Al, an experimental arrangement has been calibrated for each scattering
angle.
So, differential Compton scattering cross sections for the 12 compounds at
three scattering angles have been obtained.
The corresponding theoretical differential
cross sections were calculated by means of incoherent
scattering functions. A comparison between the experimentally determined
results and the theoretically calculated values shows good agreement.
Also, a linear relation has been obtained between
the differential Compton scattering cross sections and the hydrogen weight
fraction for H–C compounds but not for H–C–O compounds. The absolute electron
densities of these compounds have been estimated.
Development and Plasma Characteristics Measurement of Planar-Type Magnetic Neutral Loop Discharge Etcher
Authors: Shindo Yasuhiko Chinzei , Ryohei Itatani Ryohei Itatani , Takanori Ichiki Takanori Ichiki , Yasuhiro Horiike Yasuhiro Horiike
Published: October 2002

A low-pressure and high-density plasma source, called a planar-type
magnetic neutral loop discharge (NLD), has been developed for a
single-wafer etching process, employing a pair of permanent magnet rings
and a single-turn RF antenna on the quartz plate. First, the plasma
characteristics of planar-type NLD were compared with those of a
planar-type inductively coupled plasma (ICP) using the prototype etcher
with a large magnetic neutral loop (MNL) of 230 mm diameter. The results
of probe measurements in Ar plasmas have revealed that a planar-type NLD
can be sustained at low pressures of 0.1–10 mTorr with higher plasma
density and lower electron energy than a planar-type ICP. The depletion of
high-energy electrons in NLD was revealed by the direct measurement of
electron energy distribution function (EEDF) and optical emission
spectroscopy. Next, for the purpose of uniform and large-diameter NLD
generation, effects of magnetic field strength and the gap between an
antenna and a wafer stage on the plasma uniformity have been
investigated. By reducing the magnetic field strength that suppresses
plasma diffusion, an ion current uniformity within ±2.5% and a high ion
current density of 13 mA/cm2 was obtained over a 240 mm diameter in the
downstream Ar plasma. As for C4F8+90%Ar plasmas, preferable gas phase
chemistry of ion and neutral species for highly selective SiO2/Si etching
was attained due to relatively low electron energy, and a uniformity
within ±2% was also achieved over a diameter of 240 mm.
Translational Temperature Measurement for SiH2 in RF Silane Plasma Using CW Laser Induced Fluorescence Spectroscopy
Authors: Akihiro Kono Akihiro Kono , Satoshi Hirose Satoshi Hirose , Keizo Kinoshita Keizo Kinoshita , Toshio Goto Toshio Goto
Published: October 2002

Laser-induced fluorescence spectroscopy using a cw ring dye laser was
applied to the detection of low-density SiH2 in a low-power RF SiH4/Ar mixture plasma
at 40 mTorr. The translational temperature of SiH2 in the plasma was determined from
the excitation line profile and was found to be near room temperature irrespective
of the SiH4 mixing ratio.
Characteristics of Alpha-Radiation-Induced Deep Level Defects in p-Type InP Grown by Metal-Organic Chemical Vapor Deposition
Authors: Khan Aurangzeb , Iqbal Mohd Zafar , Qurashi Umar Saeed , Yamaguchi Masafumi , Zafar Nasim , Dadgar Armin , Bimberg D.
Published: October 2002

Room temperature storage and/or minority carrier injection behaviors of three
prominent majority carrier levels H3 (E
v+0.34 eV), H4 (E
v+0.39 eV) and H5 (E
v+0.58 eV) and three minority carrier levels, 0.22, 0.29 and 0.35 eV below the conduction
band edge in metal-organic chemical vapor deposition (MOCVD) grown p-type InP
crystals produced by alpha radiation have been studied using deep levels transient
spectroscopy. In particular, H5, absent immediately after irradiation, is found to grow
with storage at room temperature after irradiation with no change in the other two
majority carrier levels. Minority carrier injection saturates H5 while H3 and H4 continue
to decay after injection. These observations are interpreted to mean that H4 and H5 are
unrelated levels with no or very little mutual conversion proposed in some previous
irradiation studies. Detailed production rate data for H3, H4 and H5 (post-injection)
over a range of alpha-particle doses have also been provided for the first time.
Molecular and Crystal Structures of 2-(All-trans-Retinylidene)-Indan-1,3-Dione
Authors: Hideki Hashimoto Hideki Hashimoto , Kingo Hattori Kingo Hattori , Yoshihiro Okada Yoshihiro Okada , Takeshi Yoda Takeshi Yoda , Ryoka Matsushima Ryoka Matsushima
Published: October 2002

Molecular structures of a novel carotenoid analogue, 2-(all-trans-retinylidene)-indan-1,3-dione (RetInd), were determined in solution and in the crystalline state by 1H-NMR spectroscopy and by X-ray crystallography, respectively. They were compared with those of all-trans-retinal (Ret), a visual chromophore. Ret takes a 6s-cis configuration (a cis configuration around the C6–C7 single bond) that is usually found in carotenoid analogues that have β-end groups, both in solution and in the crystalline state. On the other hand, it was found that RetInd took a 6s-cis configuration in solution but it took a 6s-trans configuration in the crystalline state. Comparison of the crystallographic structures between Ret and RetInd lead us to the conclusion that a van der Waals attraction in polyene chains and steric repulsion between a cyclohexene and an indan-1,3-dione ring stabilized the 6s-trans configuration of RetInd in the crystalline state.
Electron-Beam Study of Nanometer Performances of the SAL 601 Chemically Amplified Resist
Authors: Gentili Massimo , Gerardino Annamaria , Di Fabrizio Enzo
Published: October 2002

The SAL 601 chemically amplified resist has been characterized for electron-beam (e-beam)
exposure with feature size down to 75 nm. The main resist process parameters such as
the pre and post exposure baking time and temperature, the resist thickness and its
development conditions, have been investigated and calibrated for sub-100 nm
resolution. Various writing strategies making use of test patterns comprising different
nominal feature-size were also investigated. Dense lines, as fine as 75 nm, are
achieved in a 350 nm thick resist with exposure latitude of 0.4 nm/µC/cm2 at 50 kV
accelerating voltage. The sub-100 nm resolution was achieved with a 3σ value of
12 nm.
Impact of Organic Contamination on Thin Gate Oxide Quality
Authors: Gendt Stefan De , Knotter D. Martin , Kenis Karine , Depas Michel , Meuris Marc , Mertens Paul W. , Heyns Marc M.
Published: October 2002

The impact of organic contamination on the quality of 5-nm-thick gate oxide structures,
both before and after gate oxidation, is studied. Sources of organic contamination are chemical
surface modification (i.e. hexamethyldisilazane priming), wafer box storage and extended
vacuum exposure. Gate oxide integrity is evaluated electrically. The origin and/or nature of the
organic contamination is seen to have different effects on the electrical breakdown. Care should
be taken when exposing silicon wafers to organic contamination prior to processing. Especially
when contamination occurs at the SiO2/polysilicon interface, i.e. prior to a non-oxidizing
process step, organics can be extremely deleterious.
Improvement of the Photoluminescence Dead Layer Model in III–V Semiconductors
Authors: Hellouin Yves , Viktorovitch Pierre
Published: October 2002

It is shown that the photoluminescence (PL) dead layer model, which is widely used in the literature to fit the variations of the room temperature PL intensity versus the surface recombination velocity of III–V compound semiconductor materials, may not be suitable to practical experimental condition. It is proposed a simple analytical derivation of the PL yield which includes the contribution of radiative recombination in the near surface field region.
Non-equilibrium Electron Dynamics Phenomena in Scaled Sub-100 nm Gate Length Metal Semiconductor Field Effect Transistors: Gate-fringing, Velocity Overshoot, and Short-channel Tunneling
Authors: Han Jaeheon , Ferry David K.
Published: October 2002

Ultrashort channel GaAs metal semiconductor field effect transistors were fabricated with gate lengths ranging from 30 nm to 105 nm, by electron beam lithography, in order to examine the scaling characteristics of transconductance. For gate lengths in sub-100 nanometer range, where gradual channel approximation is no longer valid, it was observed that the transconductance varies with a variety of small-dimension-related, nonequilibrium electron dynamics phenomena such as gate-fringing effect, electron velocity overshoot, and short-channel tunneling. Short-channel tunneling was suggested experimentally for the first time to explain the degradation of transistor performance, overriding an enhancement due to electron velocity overshoot for a gate length smaller than the average inelastic mean free path of an electron.
Electrical Instability of Hydrogenated Amorphous Silicon Thin-Film Transistors for Active-Matrix Liquid-Crystal Displays
Authors: Chiang Chun-sung , Kanicki Jerzy , Takechi Kazushige
Published: October 2002

We investigated the threshold voltage shifts (ΔV
T) of inverted-staggered hydrogenated
amorphous silicon (a-Si:H) thin-film transistors (TFTs) induced by steady-state (dc) and pulsed
(ac) gate bias-temperature-stress (BTS) conditions. Our study showed that, for an equivalent effective-stress-time, ΔV
T has an apparent pulse-width dependence under negative BTS
conditions–the narrower the pulse width, the smaller the ΔV
T. This gate-bias pulse-width
dependence is explained by an effective-carrier-concentration model, which relates ΔV
T for
negative pulsed gate-bias stress to the concentration of mobile carriers accumulated in the
conduction channel along the a-Si:H/gate insulator interface. In addition, our investigation of the
methodology of a-Si:H TFT electrical reliability evaluation indicates that, instead of steady-state
BTS, pulsed BTS should be used to build the database needed to extrapolate ΔV
T induced by a
long-term display operation. Using these experimental results, we have shown that a-Si:H TFTs
have a satisfactory electrical reliability for a long-term active-matrix liquid-crystal display (AMLCD) operation.
Study of Glass Transition in Mn-Doped Ge15Te85 Glass by Electron Spin Resonance
Authors: Chakraborty Tapan Kumar , Ueda Shoichi , Kitagawa Akio , Suzuki Masakuni
Published: October 2002

The glass transition of the Mn-doped Ge15Te85 chalcogenide glass has been
investigated during nonisothermal, rate-scan heating by electron spin resonance. The
glass exhibits two characteristic signals centered at g=2.00 and 4.3 which were
recorded during heating from room temperature to a temperature above the glass
transition but below the crystallization temperature of the glass. No significant change
in the linewidth of either of the resonance lines occurs from room temperature up to
near the glass transition temperature. However, the linewidth of the g=2.00 line begins
to decrease and that of the g=4.3 line starts to increase around the glass transition
temperature. The mechanisms of these narrowing and broadening phenomena of the
spectra observed in the supercooled liquid state are discussed.
Effects of Oxygen Gas Addition and Substrate Cooling on Preparation of Amorphous Carbon Nitride Films by Magnetron Sputtering
Authors: Yokomichi Haruo , Sakima Hiroyuki , Masuda Atsushi
Published: October 2002

Amorphous carbon nitride (a-C1-x
N
x
) films were prepared by magnetron
sputtering using nitrogen (N2) and oxygen (O2) gases in order to reduce the s
p
2
structural region and to reduce triple bonding between carbon and nitrogen atoms (C≡N)
with oxygen radical. Furthermore, these films were prepared at liquid-nitrogen
temperature in order to increase the nitrogen concentration. Electron spin resonance
(ESR), infrared (IR) absorption, ultra-violet visual (UV-vis) spectroscopy and X-ray
photoelectron spectroscopy (XPS) were used to investigate the effects of O2 gas
addition and substrate cooling on the preparation of a-C1-x
N
x
films by magnetron
sputtering.
Structural and Optical Studies of ZnCdSe/ZnSe/ZnMgSSe Separate Confinement Heterostructures with Different Buffer Layers
Authors: Tu Ru-Chin , Su Yan-Kuin , Huang Ying-Sheng , Chen Giin-Sang , Chou Shu-Tsun
Published: October 2002

Detailed structural and optical studies of ZnCdSe/ZnSe/ZnMgSSe separate
confinement
heterostructures (SCH) grown on ZnSe, ZnSe/ZnSSe strained-layer
superlattices (SLS),
and GaAs buffer layers at the II–VI/GaAs interface have been carried out
by employing
transmission electron microscopy, variable temperature photoluminescence
(PL), and
contactless electroreflectance (CER) measurements. A significant
improvement on
the defect reduction and the optical quality has been observed by using
either the
ZnSe/ZnSSe SLS or GaAs as the buffer layers when compared to that of the
sample using
only ZnSe as the buffer layer. However, the sample grown with the SLS
buffer layers
reveals a room temperature PL intensity higher than that of the sample
grown with
a GaAs buffer layer, which may still suffer from the great ionic
differences between
the II–V and III–V atoms. Using 15 K CER spectra, we have also studied
various
excitonic transitions originating from strained Zn0.80Cd0.20Se/ZnSe
single quantum
well in SCH with different buffer layers. An analysis of the CER
spectra has led
to the identification of various excitonic transitions, mnH (L), between
the mth
conduction band state and the nth heavy (light)-hole band state. An
excellent
agreement between experiments and theoretical calculations based on the
envelope
function approximation model has been achieved.
Microstructural Properties of ZrSi2 on Si(100)
Authors: Jeon Hyeongtag , Kim Sangbeom
Published: October 2002

The microstructural properties of zirconium silicide on Si(100) substrates
were investigated. The Zr thin films were deposited on Si(100) substrates by
using the electron-beam evaporation system, followed by thermal annealing at
temperatures between 500°C and 800°C, with 100°C increments. The
formation of C49 ZrSi2 was observed at the Zr/Si interface after annealing at
600°C. The sheet resistivities were found to be affected by the formation of
C49 ZrSi2. The zirconium silicide thin film annealed at 600°C showed a
significant drop in resistivity values from 184.3 µ Ω·cm to 74.3 µ Ω·cm, which
was due to the formation of C49 ZrSi2 at the Zr/Si interface. The resistivity
values of ZrSi2 were determined to be 32 µ Ω·cm after annealing at 800°C.
The chemical analysis of C49 ZrSi2 was done with AES and exhibited a good
stoichiometry of ZrSi2. The interface morphologies of zirconium silicide were
examined by transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The formation of C49 ZrSi2 was observed at
the Zr/Si interface after annealing at 600°C. The surface and interface
morphologies of the ZrSi2 film annealed at 800°C showed relatively uniform
morphologies, which indicated that C49 ZrSi2 thin films had a high resistance
to agglomeration and high thermal stability.
Aspects of the Conductivity Modulation Enhancement Effect in a 4500 V Planar Metal Oxide Semiconductor Device and Its Electrical Characteristics
Authors: Kazuya Nakayama Kazuya Nakayama , Hideo Matsuda Hideo Matsuda
Published: October 2002

A new high-power (4500 V) planar metal oxide semiconductor (MOS) device is fabricated and its properties are evaluated. It has low forward voltage drop and a large reverse bias safe operating area (RBSOA), and allows easy MOS control. These properties are superior to those of the conventional insulated gate bipolar transistor (IGBT) and the gate turn-off thyristor (GTO). This is due to the conductivity modulation enhancement effect resulting from an extremely wide gate electrode, which increases the hole storage and the electron injection. At the same time, the junction field effect transistor (JFET) resistance effect does not affect the forward voltage drop. The rate of increase of the off-state voltage (d
V
D/d
t) during the turn-off process affects RBSOA markedly, therefore, it is important to set the gate resistance to an appropriate value. The press pack device that includes 20 chips of this device and 10 fast recovery diode chips can turn off a current of 1200 A at 3600 V DC voltage supply without a snubber circuit.
Second-Harmonic Generation from Intense, 100-fs Ti:Sapphire Laser Pulses in Potassium Dihydrogen Phosphate, Cesium Lithium Borate and β-Barium Metaborate
Authors: Tamaki Yusuke , Obara Minoru , Midorikawa Katsumi
Published: October 2002

Second-harmonic generation of femtosecond, intense Ti:sapphire laser pulses is described in three 1-mm-thick nonlinear crystals of KDP (KH2PO4), CLBO (CsLiB6O10) and BBO (β-BaB2O4) in type I
phase-matching geometry. The phase-matching bandwidth is insufficient for BBO. Spectral
modulation due to cubic nonlinearity becomes significant at 200 GW/cm2 for KDP and 30 GW/cm2
for CsLiB6O10. The energy conversion efficiencies obtained at incident intensities where the spectral
modulations scarcely change the temporal profile of the second harmonic were 20% for both the
crystals. Numerical calculations including the effects of cubic nonlinearity and group-velocity
mismatch explained the experimental results. It is found that a 1-mm KDP crystal gives the most
efficient conversion for high-power, 100 fs pulses.
Numerical Simulation of a Nuclear Pumped 3He–Ne–Ar Gas Laser for its Optimization
Authors: Sakasai Kaoru , Kakuta Tsunemi , Nakazawa Masaharu
Published: October 2002

The numerical simulation of a nuclear pumped 3He–Ne–Ar gas laser (λ=585.3 nm)
has been made to estimate the optimal gas mixtures. The calculation shows that
the optimization is established under a condition of He pressure of 2280 Torr, Ne
pressure of 24 Torr, and Ar pressure of 8 Torr. The oscillation is expected to occur at a
thermal neutron flux density of 3.3×1014 cm-2 s-1 when the cavity length is 50 cm and
the mirror reflection coefficient is 99%. On the other hands, the energy efficiency
does not exceed 0.33% under the same condition.
Optimisation of Preparative and Performance Parameters on Electrochromic Properties of Electrochemically Deposited Tungsten Oxide Films
Authors: Hutchins Michael G. , Kamel Nasser A. , El-Kadry Nabila , Ramadan Ahmed A. , Abdel-Hady Kamal
Published: October 2002

Tungsten oxide films of 240–1080 nm thickness were deposited on indium tin oxide (ITO) coated glass substrates using an electrochemical deposition technique. All films were amorphous, as proved by X-ray diffraction (XRD), and had an electrical resistivity of 106 Ω·cm and spectral transmittance exceeding 75% in the visible region. The electrochromic (EC) properties were measured in situ during colouration and bleaching cycles. The EC parameters, T
sol
b, T
sol
c, ΔT
sol and Δ(OD)sol and the solar colouration efficiency ηsol were evaluated at different preparation and performance parameters. The results showed that at small film thickness, the solar colouration efficiency changes linearly and tends toward saturation at larger thickness. At colouration potentials ≥2 V, the solar colouration efficiency is almost constant whereas the active sites are transformed to colour centres. In contrast, the efficiency has an exponential dependence on electrolyte concentration. The optimum values are: film thickness = 1080 nm, colouration potential - 2 V and electrolyte concentration = 0.4 M. The corresponding EC parameters are: ΔT
sol =0.458, Δ(OD)sol=0.632 and ηsol=34 cm2/C.
GaAs Surface Passivation with GaS Thin Film Grown by Molecular Beam Epitaxy
Authors: Okamoto Naoya , Tanaka Hitoshi
Published: October 2002

We report on the successful GaAs surface passivation with GaS thin film grown by molecular beam epitaxy employing the single precursor, tertiarybutyl-galliumsulfide-cubane ([(t-Bu)GaS]4). We found that the GaAs surface reconstructions before GaS passivation influenced the interface state density. As a result, the largest GaAs bandgap photoluminescence intensity and a minimum interface state density of as low as 5×1010 eV-1 cm-2 were obtained for an As-terminated c(4×4) structure.
Characteristics of Intrinsic Josephson Junctions in a Thin Stack on Bi-2223 Thin Films
Authors: Odagawa Akihiro , Sakai Masahiro , Adachi Hideaki , Setsune Kentaro
Published: October 2002

We have successfully fabricated a small thin stack with a small number of intrinsic junctions on (Bi, Pb)2Sr2Ca2Cu3O10+xthin films. Mesa structures with the junctions are fabricated on the surface of high-quality films prepared by rf-sputtering and subsequent heat treatment. Current-voltage (I–V) responses along thec-axis show large distinct hysteresis, a clear multiple branching structure with a periodic voltage jump and the edge structure, which represents the superconductive gap. On reducing the number of the intrinsic stacked junctions, the estimated superconductive gap value increases. The thinnest stack exhibits theI–Vcharacteristic of a single junction. The value of the superconductive gap estimated from the single junction sample is about 75 meV at 4.2 K. The obtainedI–Vcurve is explained quite well by assumingdx2-y2symmetry for the superconductive order parameter without the term of gap suppression.
Raman and X-Ray Studies of InN Films Grown at Different Temperatures by Metalorganic Vapor Phase Epitaxy
Authors: Chen Wei-Kuo , Lin Heng-Ching , Pan Yung-Chung , extscOu Jehn \t , Shu Chen-Ke , Chen Wen-Hsiung , Lee Ming-Chih
Published: October 2002

We used Raman scattering and X-ray diffraction (XRD) methods to
investigate the properties of InN films deposited at temperatures
ranging from 325 to 600°C by metalorganic vapor phase epitaxy
(MOVPE). Significant line broadening, softening and intensity evolution
were observed from films at growth temperatures between 375 and
450°C. This can be attributed to the formation of mixed
hexagonal and cubic structures and related dislocation defects.
As the growth temperature was further increased, the hexagonal phase
was found to be dominant in the deposited InN film.
The Effect of Electrode Construction in Breakdown Time Lag of Impulse Breakdown in Mineral Oil
Authors: Hirai Naoshi , Akumu Aloys , Arii Kiyomitsu
Published: October 2002

A breakdown time lag of uniform and nonuniform electric fields using point-plane and
sphere-sphere electrodes in mineral oil was measured. The stainless-steel spherical electrode
was 12.5 mm in diameter. The needle electrode was made of iron and its tip was
electrolytically polished. The copper plate electrode measured 10 mm×20 mm×1 mm. The
effect on breakdown time lag wielded of differences in the distance between electrodes and
applied impulse voltage revealed that the time lag was proportional to the applied voltage
and the breakdown time lag of a nonuniform electric field was shorter than that of a uniform
electric field. It was found that the breakdown phenomena in point-plane and sphere-sphere
electrodes were respectively similar to a streamer-type breakdown and a streamer
breakdown structure.
Effects of Nitrogen Addition to Fluorinated Silicon Dioxide Films
Authors: Hasegawa Seiichi , Saito Atsusi , Lubguban Jorge A. , Inokuma Takao , Kurata Yoshihiro
Published: October 2002

Amorphous fluorinated silicon dioxide (a-SiO2:F) films doped with nitrogen were deposited by
changing the ammonia flow rate using plasma-enhanced chemical vapor deposition from SiH4–O2–CF4–NH3 mixtures. The effects of nitrogen addition to the films on both the dielectric constant (ε
s)
determined from the capacitance vs. voltage characteristics and the bonding properties examined by
infrared absorption measurements, were investigated. These results were also discussed in terms of
a change in the partial charge on the constituent Si, O, F and N atoms caused by adding F and N
atoms to SiO2 films. When a-SiO2 films are doped by 2-3 at.% with both fluorine and
nitrogen under high rf power and high deposition temperature (T
d) conditions, films with low ε
s(≈3.2) and high water resistivity were obtained. It was suggested that Si–F bonds, which act to
decrease ε
s value, are stabilized by forming Si–N bonds near the Si–F bonds and by removing
weaker Si–F bonds under high rf power and high T
d.
Scattering Characteristics of the Chiral Slab for Normally Incident Transverse Waves
Authors: Ro Ruyen
Published: October 2002

The elastic field behavior in a chiral medium is readily described using governing equations
and constitutive relations for noncentrosymmetric, isotropic micropolar materials. Accordingly,
two longitudinally, two left circularly and two right circularly polarized elastic waves can propagate
in a chiral medium. Using appropriate field representations along with prescribed boundary
conditions, scattering characteristics at chiral interfaces can be readily determined. In this paper,
reflection and transmission characteristics of the chiral slab bounded by achiral media for normally
incident transverse waves are thoroughly discussed. The method for approximately determining the
vanishing reflection of the chiral slab over related frequency ranges is elucidated. Simulation results
show that the scattering characteristics of the chiral slab can be designed by tailoring the material
properties. These results can be used to design acoustic impedance transformers and acoustic
absorbers.
Fe3Si Phase Formation at Fe/Si(111)-7×7 Interface at Room Temperature Studied by Semiempirical Theory
Authors: Ho Kim Kun , Duk Lee Jong , Jeongsoo Kang Jeongsoo Kang
Published: October 2002

The reaction at the Fe/Si interface and the growth mode of Fe on Si(111)-7 ×7
substrate at room temperature were investigated.
The Si-2p core level photoemission spectra as a
function of deposited Fe thickness were measured, and were analyzed by the modified
Butera's model based on the semiempirical theory. Islands of
Fe3Si phase were formed in the unreacted Fe matrix on Fe thickness of about
1 Å to 10 Å and silicide growth was restricted to the Fe thickness.
Bulk Fe was grown by further Fe-deposition.
Growth Mechanisms of Aluminum Dots Deposited by Laser-induced Decomposition of Trimethylamine Alane
Authors: Tonneau Didier , Thuron Frédéric , Correia Antonio , Bouree Jean Eric , Pauleau Yves
Published: October 2002

Aluminum dots have been deposited by thermal decomposition
of trimethylamine alane (TMAA) on silicon substrates irradiated
with a tightly focused argon ion laser beam (λ=514 nm). Carbon
free Al deposits containing less than 5 at.% of impurities
(mainly oxygen) detected by Auger Electron Spectroscopy were
grown. The growth kinetics of Al dots was investigated as a
function of TMAA pressure and laser-induced temperature. The
deposition of dots occurred at a laser-induced temperature as
low as 210°C. The TMAA decomposition was thermally activated
(activation energy of 18 kcal/mole) and the deposition rate at
300°C was equal to 2 µm/s. The effects of H2 or He (used as
buffer gases) in the gas phase on the growth kinetics of dots
was also studied. The growth mechanisms of dots are discussed
and proposed on the basis of the results of this kinetic study.
Gas Sensing Properties of Indium Oxide Thin Film on Silicon Substrate Prepared by Spin-Coating Method
Authors: Chung Wan-Young , Sakai Go , Shimanoe Kengo , Miura Norio , Lee Duk-Dong , Yamazoe Noboru
Published: October 2002

Thin films of indium oxide were prepared on a silicon substrate by a spin-coating method using a coating solution dissolving In(OH)3, acetic acid and ammonium
carboxymethyl cellulose. The films consisted of a dense stack of fairly uniform grains,
adhering well to the substrate, as observed with atomic force microscopy (AFM) and
scanning electron microscopy (SEM). The film thickness was well controlled by
repeating the spin-coating. The sensing properties of the In2O3 film to CO, H2 and C3H8
depended on the film thickness and temperature, fairly good sensing performance to CO
being achieved with a 140-nm-thick film at 350°C. The contact between platinum
electrode and In2O3 in these devices was found to be slightly non-Ohmic, unlike that in
the sintered block type device.
Dissociation Thresholds of Low-Energy Molecular Ions on a Cu(111) Surface
Authors: Yamamoto Hiroyuki , Baba Yuji , Sasaki Teikichi A.
Published: October 2002

The dissociation thresholds of polyatomic SF5
+ and BF2
+ ions on Cu(111) surface
have been investigated in the incident energy range of 2–200 eV. The mass and kinetic
energy of scattered ions were analyzed simultaneously using a quadrupole mass analyzer
equipped with a 45° sector field energy filter. For SF5
+ ion irradiation, dissociated
species (SF4
+ and F-) began to emerge at an energy of 15±2 eV, and the irradiated ions
further dissociated into SF3
+ at 50±2 eV. These energies are substantially higher than the
bond strength of S–F for free SF6 molecules (3.3 eV). These results suggest that the
translational-vibrational energy transfer during the collision process greatly affects the
observed dissociation threshold. Similar results are also observed for BF2
+ irradiation.
Slant Slot Antenna-Type Electron Cyclotron Resonance Plasma Source
Authors: Watanabe Seiichi , Tamura Hitoshi , Sumiya Masahiro , Furuse Muneo , Kawasaki Sunao
Published: October 2002

A new compact electron cyclotron resonance (ECR) plasma source, which is termed
slant-slot antenna-type ECR plasma source, is presented. Using this plasma source an ion
saturation current density I
is of 6.2 mA/cm2±5.2% was obtained over a diameter of 300 mm under
ambient conditions of Cl2 gas at 0.7 Pa. The features of the plasma source are an independent
circular TM011 mode cavity resonator and slot antennas mounted in the shape of a ring at a
constant slant angle to the surface current flowing at the bottom of the cavity resonator. As the
result, microwaves of TE01 mode and others having a ring-shaped the electric field distribution can
be introduced into the reaction chamber with high stability. This plasma source can generate a
plasma with a ring-shaped I
is distribution stably, and it can control the I
is distribution by means of
both the configuration of the magnetic field and the pattern of slot antennas. Therefore, the plasma
source can generate a uniform plasma under a wide range of discharge conditions.
Lifetime Measurements of CFx Radicals and H Atoms in Afterglow of CF4/H2 Plasmas
Authors: Koichi Sasaki Koichi Sasaki , Kenichiro Usui Kenichiro Usui , Hiroyuki Furukawa Hiroyuki Furukawa , Chihiro Suzuki Chihiro Suzuki , Kiyoshi Kadota Kiyoshi Kadota
Published: October 2002

Decay time constants of CFx radical and H atom densities were measured
in the afterglow of high-density CF4 plasmas following
the addition of H2.
The lifetimes of CFx and H for high H2 partial percentages (>25%)
were several tens of times longer than those for
low H2 partial percentages (<15%).
The long lifetimes of both CFx and H observed
for high H2 percentages
suggest that the rate coefficient for the gas-phase
reaction CFx + H →CF
x-1 + HF
is much smaller than the values reported in literature.
Mechanism of Etch Stop in High Aspect-Ratio Contact Hole Etching
Authors: Ohiwa Tokuhisa , Kojima Akihiro , Sekine Makoto , Sakai Itsuko , Yonemoto Shigeru , Watanabe Yumi
Published: October 2002

The mechanism of etch stop in contact hole etching has been
studied. It was found that in high aspect ratio holes, even though
the incident ions lose charge due to collision with the sidewall,
they are able to bombard the bottom of the hole maintaining their
high energy. It was also confirmed that the redeposition of
sputtered species from the fluorocarbon polymer on the hole sidewall
induces the etch stop at the bottom of the high-aspect hole.
Furthermore, it was observed that etch stop occurs at higher aspect
ratios for the same hole diameter in oxide films with higher boron
and phosphorous dopant concentrations. This is explained by the
effective removal of etch-inhibiting carbon species due to the
release of more oxygen at a higher etch rate in highly doped oxide
film. In conclusion, the etch stop in a high-aspect-ratio hole is
determined by the balance between the effects of high-energy-species bombardment and etch inhibition of carbon species.
On the Polymer Thickener for Viscosity-Stabilized Solar Pond
Authors: Matsumoto Toshiro , Kato Nobuhiro , Taga Masao
Published: October 2002

The optimal physical properties of an ionized polyacrylamide solution, selected as the most suitable thickener for the insulating layer of a
viscosity-stabilized solar pond, are described. Light transmittance,
viscosity and viscosity degradation were obtained for a range of
thicknesses from 1 cm to 15 cm (1–15 cm), weight concentrations of
0.1–0.5% (0.1–0.5 wt%) and temperatures of the polymer of 20–80°C. Onset of co
nvection was also measured for a given thickness of the polymer
solution. An exposure test was carried out to prevent degradation of the
polymer using an antioxidant. It was confirmed that the viscosity was not
decreased and, on the contrary, increased slightly after 100 days. It was
shown experimentally that the critical Rayleigh number coincided
with the theoretical values reported by Tien et al.. [Int. J. Heat Mass
Transf. 12 (1969) 1173]. Transmittances of the polymeric gel for the case of
vessels greater than 5 cm in thicknesses were better than those of the
SPR402 solution (0.5 wt%).
Magnetoluminescence Study on the Low-Dimensionality of Excitons Confined in a Narrow GaAs/AlGaAs Quantum Well
Authors: Hyunsung Ko Hyunsung Ko , Dae-Wook Kim Dae-Wook Kim , Woosik Kim Woosik Kim , Do Hyun Kim Do Hyun Kim , Young Ahn Leem Young Ahn Leem , Yongsoo Kim Yongsoo Kim , Jong-Chun Woo Jong-Chun Woo , Thomas Schmiedel Thomas Schmiedel
Published: October 2002

Low-dimensional characteristics of excitons confined in a quantum well (QW) are studied by applying a high magnetic field (B). The diamagnetic shift is best fit with a linear combination of linear and quadratic terms of B. From the quadratic dependence of B, it is obtained that the exciton becomes two-dimensional (2-D) like when the QW width decreases to 15 monolayers (ML). However, the 2-D confinement becomes weak when the width becomes smaller than 10 ML. In large B, the field confinement becomes significant in the electron-hole recombination, and the population inversion of the photo-generated carriers in the islands of ML fluctuation was observed.
Preparation of Lead Titanate Thin Films Using Langmuir-Blodgett Method
Authors: Sugai Hiroshi , Hoshi Nobuo , Iijima Takashi , Masumoto Hiroshi
Published: October 2002

The Langmuir-Blodgett (LB) method is investigated as a process in the
fabrication of ferroelectric thin films such as lead titanate. LB film was fabricated by
depositing a monolayer prepared by stearic acid (C17H35COOH), lead chlorides (PbCl2)
and titanium bis(ammonium lactato)([CH3CH(O–)CO2NH4]2Ti(OH)2). As a conversion
process from the LB film containing lead and titanium to an inorganic film, ultraviolet/ozone (UVO) treatment was found to be extremely applicable at a rate of about 4 min per monolayer. Subsequent rapid thermal annealing (RTA) resulted in a dense oxide
thin film. The thickness of an oxide thin film converted from the LB film consisting of
301 layers was approximately 30 nm. Hence, it is considered that approximately 0.1 nm
of the oxide layer is equivalent to the thickness of the film deposited by each cycle.
From an X-ray diffraction pattern of the oxide specimen, a well-defined perovskite
peak structure was observed. These results demonstrate the potential application of LB
deposition for the preparation of an inorganic oxide film such as lead titanate.
Thermally Stimulated Current and Polarization Fatigue in Pb(Zr,Ti)O3 Thin Films
Authors: Hirotake Okino Hirotake Okino , Yoshiaki Toyoda Yoshiaki Toyoda , Masaru Shimizu Masaru Shimizu , Toshihisa Horiuchi Toshihisa Horiuchi , Tadashi Shiosaki Tadashi Shiosaki , andKazumi Matsushige andKazumi Matsushige
Published: October 2002

In order to clarify the origin of the polarization fatigue phenomena,
charge traps in ferroelectric Pb(Zr,Ti)O3 (PZT) thin films
were measured using the thermally stimulated current (TSC) technique.
For polarization fatigued Pt/PZT/Pt/SiO2/Si(100) capacitors,
a peak of TSC was observed, and
the trap density estimated from the TSC data
increased as switching cycles increased.
Activation energy and density of the charge traps
were estimated to be 0.7–0.8 eV and
on the order of 1018 cm-3,
respectively.
It was also observed that
degradation of remanent polarization of PZT
was improved by the TSC measurement process.
On the other hand, no TSC peak was observed for
fatigue free Ir/PZT/Ir/IrO2/SiO2/Si(100) capacitors.
From these results, it was suggested that
the main origin of the polarization fatigue phenomena
was the domain pinning caused by trapped charge carriers
injected by polarization reversal.
Material Properties of Heteroepitaxial Ir and Pb(ZrxTi1-x)O3 Films on (100)(ZrO2)1-x(Y2O3)x/(100)Si Structure Prepared by Sputtering
Authors: Horita Susumu , Horii Sadayoshi , Umemoto Shinya
Published: October 2002

We investigated the crystalline quality and electrical
properties of heteroepitaxial Ir and Pb(Zr
x
Ti1-x
)O3 films
deposited by sputtering on an epitaxial (100)(ZrO2)1-x
(Y2O3)
x

film/(100)Si substrate structure. The Ir(100) and Ir(111)
orientations were enhanced and reduced, respectively, by
decreasing the deposition rate. The φ scan pattern of X-ray
diffraction showed that the (100) oriented film was the
heteroepitaxial film on the epitaxial (100)YSZ film with a
cube on cube relationship. On this epitaxial (100)Ir film, a
heteroepitaxial (001)PZT film was obtained by reactive
sputtering. The P–E hysteresis loop of the 200-nm-thick
epitaxial PZT film showed a well-saturated square shape at
the ac amplitude of 3 V, and the remanent polarization 2P
r
and the coercive field 2E
c were 83 µC/cm2 and 131 kV/cm,
respectively. The leakage current was about 1×10-7 A/cm2 at
±5 V.
Characterization of Pb(Zr, Ti)O3 Thin Films on Si Substrates Using MgO Intermediate Layer for Metal/Ferroelectric/Insulator/Semiconductor Field Effect Transistor Devices
Authors: Senzaki Junji , Kurihara Koji , Nomura Naoki , Mitsunaga Osamu , Iwasaki Yoshitaka , Ueno Tomo
Published: October 2002

Pb(Zr, Ti)O3(PZT)/MgO/Si(001) stacked structures, one of the potential
components of ferroelectric-gate field effect trnsistors, have been fabricated and characterized. According
to the electrical characterization of MgO/Si structures, MgO thin films prepared on Si
substrates at a low growth rate showed a small leakage current of ∼10-8 A/cm2 order in an
electric field of 1 MV/cm. In C-V measurements of as-grown MgO/Si interfaces,
injection-type hysteresis was observed because of crystal defects in the MgO film adjacent
to the interface. After oxygen annealing at 400°C, however, it showed no hysteresis and a
low interface trap density of the order of 1011 cm-2eV-1 was achieved with no formation of a
low-dielectric layer at the MgO/Si interface. These results indicate that MgO thin films are
applicable as gate insulators of FETs. After a PZT film was deposited on the MgO/Si
structure, the C-V characteristic of the stacked structure showed a ferroelectric hysteresis
curve and a low interface trap density of 5×1011 cm-2eV-1. A maximum memory window
width of 1.2 V was obtained for the PZT thin film on Si substrate with a MgO intermediate
layer.
Preparation of 0.92PbZrO3–0.03PbTiO3–0.05Pb(Zn1/3Nb2/3)O3 Pyroelectric Thick Films by Screen Printing
Authors: Futakuchi Tomoaki , Matsui Yoshinari , Adachi Masatoshi
Published: October 2002

Pyroelectric thick films of 0.92PbZrO3–0.03PbTiO3–0.05Pb(Zn1/3Nb2/3)O3
were prepared by a screen printing method
on ceramic substrates using platinum bottom electrodes. A phase
transition between two rhombohedral ferroelectric phases was
observed for the poled thick film through the measurement of
the temperature dependence of pyroelectric coefficient. The
effects of the firing temperature and the types of ceramic
substrates were examined. These pyroelectric thick films are very
promising for use in the fabrication of highly sensitive infrared
array detectors.
Voltage Shift Effect on Retention Failure in Ferroelectric Memories
Authors: Nakao Keisaku , Judai Yuji , Azuma Masamichi , Shimada Yasuhiro , Otsuki Tatsuo
Published: October 2002

We investigated the origin of retention failure in ferroelectric memories (FeRAMs) with
SrBi2(Ta, Nb)2O9 (SBTN) memory cell capacitors by considering the time-dependent behavior
of polarization vs. voltage (P-V ) curves of the capacitors during high-temperature storage.
Since the SBTN capacitors exhibited no marked decrease in the nonvolatile component of
polarization even after high-temperature storage, we focused on the effect of voltage shift
observed in P-V curves. We calculated bitline voltage along the storage from the P-V curves
and the bitline capacitance, and successfully estimated a decrease in the bitline voltage, which is
in agreement with the retention failure in FeRAMs. In addition, the calculation indicated that the
lifetime limited by the retention failure in FeRAMs with SBTN capacitors at 125°C exceeds 10
years.