bluuebunny/crossref_metadata_2025 huggingface dataset:
Mg-related Deep Levels in AlInP
Authors: Wu Yu-Rue , Sung Wei-Jer , Lee Shih-Chang , Li Tsang-Jou , Lee Wei-I.
Published: October 2002

The properties of deep levels found in Mg-doped AlInP, grown by metal-organic
chemical vapor deposition, have been studied. Two distinct levels, labeled E1 and E2,
were observed, with the activation energy of 0.19 and 0.514 eV, respectively. From
distribution profiles measured on trap E1, E2 and Mg-dopant, all three concentration
profiles have similar behaviors. The concentration increases gradually from the
interface of pn junction. Furthermore, both trap E1 and E2 concentration increase
with elevating Mg-dopant concentration. Thus, it seems that these deep levels
originate from Mg-related defects.
Theoretical Study on Data Transfer Rate of Near-Field Photochromic Memory
Authors: Tsujioka Tsuyoshi , Irie Masahiro
Published: October 2002

The data transfer rate of near-field photochromic memory was theoretically studied.
The data transfer rate for the medium with the sensitivity ε
B=104 and φBA=0.1 in the
recording process was about 1 kilo bps (bits per second) at the light power density of
102 W/cm2, but it increased to over 1 Mbps at 105 W/cm2. Fluorescence and
reflectance detection readout methods of a near-field photochromic optical memory
were also theoretically studied. The data transfer rate at the light power of 10-6 W in
the readout process was around 1–10 Mbps. When the average reflectance is high,
there is a benefit of using a fluorescence detection method for obtaining a high data
transfer rate.
Control of Dot Size and Tunneling Barrier Profile in In0.53Ga0.47As Coupled Quantum Wire-Dot Structures Grown by Selective Molecular Beam Epitaxy on Patterned InP Substrates
Authors: Fujikura Hajime , Hanada Yuuki , Muranaka Tsutomu , Hasegawa Hideki
Published: October 2002

Efforts were made to control the dot size and tunneling barrier
profiles in In0.53Ga0.47As coupled quantum wire-dot-wire structures
formed by selective molecular beam epitaxial (MBE) growth on patterned
InP substrates. According to detailed investigation using a scanning
electron microscope (SEM), atomic force microscope (AFM) and
cathodoluminescence (CL) spectroscopy, the size of the quantum dot and
the lateral width of the potential barrier can be controlled by
suitably selecting growth conditions and pattern geometry. A minimum
dot width and lateral barrier width of about 100 nm and 80 nm,
respectively, were achieved in a controlled fashion, indicating
applicability of the present approach to direct formation of
single-electron transistor (SET) arrays.
Correlation Studies on Fast Electrons and Dynamo-Related Activities in a Reversed-Field Pinch Plasma
Authors: Yagi Yasuyuki , Serianni Gianluigi , Ji Hantao , Maejima Yoshiki
Published: October 2002

Correlation of fast electron current with magnetohydrodynamic activities is studied extensively in the edge of a reversed-field pinch (RFP) plasma in TPE-1RM20 using a complex probe in order to examine the origin of the driving force for fast electrons in RFP plasma. The fast electron current is found to have a statistically meaningful coherence with thev×bdynamo electric field. However, the coherence is small and the fast electron current has finite correlations with the global magnetic modes which rotate toroidally and poloidally. Correlation with the externally applied electric field is also examined and is found to be small. Overall correlation studies are discussed in terms of the possible driving sources of fast electrons.
Effects of O2- and N2O-Plasma Treatments on Properties of Plasma-Enhanced-Chemical-Vapor-Deposition Tetraethylorthosilicate Oxide
Authors: Chen Ying-Chia , Yang Ming-Zang , Tung I-Chung , Chen Mengpang , Feng Ming-Shiann , Cheng Huang-Chung , Chang Chun-Yen
Published: October 2002

The high quality silicon oxide films were prepared by plasma-enhanced
chemical vapor deposition (PECVD) using tetraethylorthosilicate (TEOS)-oxygen based chemistry. The O2- or N2O-plasma treatments were
performed on the as-deposited films as an attempt to improve the properties
of the TEOS oxide films. TEOS oxide film deposited at lower pressure had
lower Si–OH content, less carbon impurity, and flatter surface, and hence
had better electrical properties. Both O2- and N2O-plasma would decrease
the oxygen content of the oxide film, which led the composition of the film
to deviate from the stoichiometric SiO2. The O2-plasma treatment did not
show the encouraging effect on the chemical structure and electrical
properties of the TEOS oxide films. In contrast, the N2O-plasma
treatment could be a promising means to improve the breakdown field and
leakage current density of the TEOS oxide films, which was accomplished
by the N2O-plasma effect to facilitate the passivation of dangling bonds,
linking reaction of Si–OH bonds, nitridation reaction and densification of
the amorphous silicon oxide network.
Mesa-supported, Single-crystal Microstructures Fabricated by the Surface/Bulk Micromachining Process
Authors: Sangjun Park Sangjun Park , Sangwoo Lee Sangwoo Lee , Sangwoo Yi Sangwoo Yi , Dong-il Dan Cho Dong-il Dan Cho
Published: October 2002

In fabricating microelectromechanical systems (MEMS), bulk micromachining
using (100) and (110) single crystal silicon and surface micromachining using
polycrystalline silicon are most commonly used. However, both micromachining
methods have drawbacks, and fabricating actuating or sensing microdevices
using single crystal silicon has been an active research topic in recent years.
The surface/bulk micromachining (SBM) process using (111) silicon, developed
by us previously, allows fabricating released
structures in single crystal silicon. This paper extends the SBM process to
fabricate released structures that are anchored to the substrate via mesa islands. This allows
fabricating folded-type comb drive resonators. With the extension of the SBM
process developed in this paper, any microstructure fabricated by the one structural
polysilicon surface micromachining technique can also be fabricated in single crystal silicon.
Downstream Control of Negative-Ion Plasma Parameters in Helicon Discharge
Authors: Fujita Mahmood Nasser
Published: October 2002

Plasma parameters, such as electron temperature, plasma density and potential oscillation were controlled by applying a negative potential to a grid in the downstream region of an electronegative plasma excited by an m = ± 1 mode helical antenna. The fine mesh grid, with spacing comparable to the Debye length was found to quench the plasma characteristics in the source region whereas the coarse mesh grid did not. The fine mesh grid performed better cooling of the electron temperature and lowered the plasma oscillation. Oscillating amplitude was found to increase with an increase in the SF6 gas concentration, while the time-averaged space potential was found to decrease, implying the effect of negative ions. The measurement of positive ion energy distribution functions predicted an ion beam travelling from the plasma source region towards the diffused region because of the potential difference between the two regions separated by the grid bias.
Novel GaAs Quantum Wire and Dot Arrays by Hydrogen-Assisted Molecular Beam Epitaxy on High-Index Substrates
Authors: Ploog Klaus H. , Nötzel Richard
Published: October 2002

Dense arrays of quantum wires and quantum dots with large confinement energy and very uniform size distributions are needed for realistic device applications. Significant progress has been achieved by combining self-organized growth on high-index substrates with lithographic patterning and atomic hydrogen assistance. We report here on the fabrication of GaAs quantum wire and quantum dot arrays with superior electronic properties by molecular beam epitaxy. Our new method additionally allows to precisely position the wires and dots on specific wafer areas.
Patterned Platinum Etching Studies in an Argon High-Density Plasma
Authors: Delprat Sébastien , Chaker Mohamed , Margot Joëlle
Published: October 2002

Plasma etching of platinum was investigated using a high-density surface-wave argon plasma
operated in the low pressure regime. The substrate was RF biased up to 150 V. The influence of
the ion density and of the DC selfbias voltage on the sputter-etching characteristics was
investigated at a gas pressure of 1 mTorr. It was found that, at this low pressure, the etch rate is an
increasing function of both the ion density and the self-bias voltage. High etch rates with a good
selectivity over resist, good Pt sidewall angle and fence-free submicron features have been achieved
using bias voltages lower than 150 V.
Prospects of Thickness Reduction of the CdTe Layer in Highly Efficient CdTe Solar Cells Towards 1 µm
Authors: Nowshad Amin Nowshad Amin , Takayuki Isaka Takayuki Isaka , Tamotsu Okamoto Tamotsu Okamoto , Akira Yamada Akira Yamada , Makoto Konagai Makoto Konagai
Published: October 2002

This study focuses on the technique for the stable growth of CdTe (1.44 eV) with thickness near its absorption length, 1 µm, by close spaced sublimation (hereafter CSS) process, in order to achieve high conversion efficiency. X-ray diffraction (XRD) spectroscopy was carried out to examine the microstructure of the films. Current-voltage (I–V) characteristics, spectral response and other features of the solar cells using these CdTe films were investigated to elucidate the optimum conditions for achieving the best performance in such thin (1 µm) CdTe solar cells. Thickness was found to be reduced by controlling the temperature profile used during CSS growth. The temperature profile was found to be an important factor in growing high-quality thin films. By controlling the growth parameters and optimizing the annealing temperature at different fabrication steps, we have succeeded, to date, in achieving cell efficiencies of 14.3% (open-circuit voltage (V
oc): 0.82 V, short-circuit current (J
sc): 25.2 mA/cm2, fill factor (F.F.): 0.695, area: 1 cm2) with 5 µm, 11.4% (V
oc: 0.77 V, J
sc: 23.7 mA/cm2, F.F.: 0.63, area: 1 cm2) with 1.5 µm and 11.2% (V
oc: 0.77 V, J
sc: 23.1 mA/cm2, F.F.: 0.63, area: 1 cm2) with only 1 µm of CdTe layer thickness at an air mass of 1.5 without antireflection coatings. This is important for establishing a strong foundation before developing a new structure (e.g., glass/ITO/CdS/CdTe/ZnTe/Ag configuration) with a back surface field of wide-bandgap material (e.g., ZnTe).
Intrinsic Polarised Emission from InAs/GaAs(311)A Quantum Dots
Authors: Sanguinetti S. , Castiglioni S. , Grilli E. , Guzzi M. , Panzarini G. , Andreani L. C. , Henini M.
Published: October 2002

Dependence on the exact growth condition of the InAs/GaAs quantum dot emission polarisation has been tested for (100) and (311)A substrates. Polarised emission, reproducible in intensity and direction and independent of the coverage, has been achieved by self-assembling InAs quantum dots on (311)A GaAs substrates only. The quantum dots emission is stably polarised along the [233] crystallographic direction with a polarisation ratio of about 12%.
The Effect of Band Gap Narrowing and Two-Dimensional Grain on High-Temperature Properties of Polysilicon Emitter Bipolar Junction Transistors
Authors: Hong Gia M. , Gong Jeng , Lu Shu C. , Lin Jian Y.
Published: October 2002

A two-dimensional model with grain boundary traps for polycrystalline silicon is
used in this study to analyze the temperature effects of polysilicon emitter bipolar
junction transistors (PEBJTs). The base current, the collector current, and the band
gap narrowing of the transistor have been examined in the temperature range of 25°C
to 150°C. The experimental results agreed well with the theoretical simulations.
A Dopant-Related Defect in Te-Doped AlInP
Authors: Wu Yu-Rue , Sung Wei-Jer , Wen Tzu-Chi , Lee Shih-Chang , Lee Wei-I
Published: October 2002

A deep level in Te-doped Al0.5In0.5P, grown by metal organic chemical vapor
deposition, has been studied by deep level transient spectroscopy. The thermal
activation energy was 0.24 eV, and the trap concentration was related to Te-dopant
concentration. The deep level concentration strongly increased with elevating Te-dopant
concentration. Meanwhile, the trap distribution profile also presented the same
distribution behavior as the Te concentration profile. Therefore, the deep level in
Te-doped AlInP is verified to be a dopant-related defect.
Selective-Area Growth of Magnetic Garnet Crystals by Liquid-Phase Epitaxy and Its Application to Waveguide Devices
Authors: Yokoi Hideki , Mizumoto Tetsuya , TomoakiTakano TomoakiTakano
Published: October 2002

Magnetic garnet layers with the composition of (LuNdBi)3(FeAl)5O12 have been
grown on (111)-oriented Gd3Ga5O12 (GGG) substrates, which are patterned with stripes
of different widths using a Ti mask, by liquid-phase epitaxy to fabricate one-step grown
magnetic garnet waveguides. The garnet layers were investigated by scanning electron
microscopy, X-ray diffraction measurements, energy-dispersive X-ray analysis and
reflection high-energy electron diffraction. The layers grown on Ti-masked regions had a
coarse and uneven surface, which is attributed to the damage in the surface of GGG
substrates during the growth. The waveguiding experiment indicated that the light waves
could be guided within the waveguide with a propagation loss of
approximately 0.7 dB/mm.
Room Temperature Deposition of Silicon Nitride Films for Passivation of Organic Electroluminescence Device Using a Sputtering-Type Electron Cyclotron Resonance Plasma
Authors: Gao Dawei , Furukawa Katsuhiko , Gao HiroshiNakashima , Wang Junli , Muraoka Katsunori
Published: October 2002

Dense silicon nitride (SiN) films were deposited at room temperature by a sputtering
technique using an electron cyclotron resonance (ECR) plasma. Film properties were
studied using ellipsometry, chemical etching, Fourier transform infrared spectroscopy, and
thermal desorption spectroscopy. A SiN film deposited under the optimum condition of
nitrogen gas flow rate had a refractive index of 2.03 and showed a
large Si–N bond number. The SiN film had a high barrier against moisture penetration relative to SiN films prepared by
chemical vapor deposition at 900°C. This indicates that the film deposited using a
sputtering-type ECR plasma has the potential to be utilized as a passivation layer of devices
such as organic electroluminescence, which require low temperature processing.
Ion Temperature Estimated from Energy Dependence of Ion Flux to a Plasma End
Authors: Satoshi Kabaya Satoshi Kabaya , Akira Tsushima Akira Tsushima
Published: October 2002

Ion temperatures have been experimentally estimated from the exponential parts of volt-ampere characteristics of ion flux obtained using retarding field analyzers. This report concerns the feasibility of this measurement for a plasma with a uniform particle source, using an electrostatic particle simulation code. The results show that an ion temperature estimated from the ion flux to a plasma end is about twice as high as the ion temperature at the plasma center.
High-Efficiency Amorphous Silicon Solar Cells with ZnO as Front Contact
Authors: Sang Baosheng , Dairiki Koji , Yamada Akira , Konagai Makoto
Published: October 2002

B-doped ZnO films deposited by the photo-induced metalorganic chemical vapor
deposition (photo-MOCVD) method were applied to p-i-n single junction amorphous silicon (a-Si) solar cells as front contacts. The thickness and the doping level of the p-layer were optimized in order to increase the open-circuit voltage (V
oc) of the
fabricated a-Si solar cells. As a result, a stabilized conversion efficiency of 8.7% (V
oc: 0.926 V, J
sc: 14.6 mA/cm2, FF: 0.646) was achieved under AM 1.5 (100 mW/cm2)
illumination. Furthermore, the electrical properties of ZnO films were improved by
employing an atomic layer deposition (ALD) technique instead of the conventional
MOCVD method, and a lower resistivity of 5×10-4 Ωcm was achieved. It was also
found that the stability of the electrical properties of ZnO films was improved by the
ALD technique. The performance of the a-Si solar cells was further improved by
applying the obtained high-quality ZnO films.
Crystallographic Properties of Closely Stacked InAs Quantum Dots Investigated by Ion Channeling
Authors: Tsuyoshi Ishigure Tsuyoshi Ishigure , Tetsuya Haga Tetsuya Haga , Shunichi Muto Shunichi Muto , Yoshiaki Nakata Yoshiaki Nakata , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

The crystallographic properties of InAs quantum dots with thin
GaAs(<20 nm) intermediate layers have been investigated by ordinary
Rutherford backscattering and particle induced X-ray emission measurements.
The results reveal that lattice defects of In increase with a decrease in
thickness of the GaAs intermediate layers.
We also studied the dependence of channeling on the incident energy,
and found that five stacked InAs quantum dots with 1-nm-thick GaAs
intermediate layers were very different from those with thicker
intermediate layers.
Wavelength Tuning of GaAs/AlGaAs Quantum-Well Infrared Photodetectors by Thermal Interdiffusion
Authors: Liu Xingquan , Li Ning , Chen Xiaoshuang , Lu Wei , Xu Wenlan , Yuan XianZhang , Li Na , Shen S. C. , Yuan Shu , Tan Hark Hoe , Jagadish C.
Published: October 2002

Thermal interdiffusion is used to shift peak response wavelength of quantum well
infrared photodetectors. A maximum 0.7 µm red-shift for 900°C annealed devices
compared with as-grown one has been obtained. Error function potential profile is used to
calculate the intermixing process. The large red-shift is attributed to Si-dopant enhanced
intermixing. Dark current is decreased about 5 times for 900°C annealed sample than
as-grown one, which is attributed to Si-dopant out-diffusion. The experimentally observed
reduction in the responsivity is attributed to out-diffusion of Si-dopant and degradation of
interfaces.
Frequency Dependence of Nonlinear Susceptibility of Methyl Orange Embedded in Poly(vinyl alcohol) Matrix: Two-Wave Mixing Study
Authors: Lee Geon Joon , Jang Yong Kyu , Kim Wook Sung , Lim Tong Kun
Published: October 2002

The optical frequency detuning characteristics of magnitude and
phase of nonlinear susceptibility were investigated in a methyl
orange-doped poly(vinyl alcohol) thin film. The negative ratio
(-n
2
′/n
2
′′) of the real part to the
imaginary part of the complex nonlinear refractive index is found to
increase linearly with the detuning parameter (δ) as predicted in
the two-level model. It is also found that the magnitude of the
complex nonlinear refractive index decreases as the input frequency
approaches the resonance frequency due to a depletion in the number of
trans molecules parallel to the polarization direction of the light wave.
Raman Scattering of 0.91Pb(Zn1/3Nb2/3)O3–0.09PbTiO3Relaxor Ferroelectric Single Crystals
Authors: Jiang Fuming , Kojima Seiji
Published: October 2002

Raman spectra were measured for lead zinc niobate-lead titanate solid solution 0.91Pb(Zn1/3Nb2/3)O3–0.09PbTiO3single crystals over a wide temperature range (-170–650°C) with different scattering geometry. Two phase changes were clearly observed by Raman scattering at the cubic to tetragonal (TC–T) and tetragonal to rhombohedral (TT–R) phase transition temperatures. The low-temperature transition related to the nanoregion behaviors has not been reported by other authors in the Raman scattering of other relaxor materials, and the mechanism was attributed to the increase in order at the B-site in 0.91PZN–0.09PT. High-temperature Raman spectra aboveTC–Twith well-defined polarization are evidences that the Raman modes are mainly of the first order. The temperature dependence of the Raman modes aboveTC–Tis due to the distorted space group of Fm3m associated with the positional disorder of Lead ion and the gradual disappearance of nanoregions with increasing temperature.
High-Resolution Soft X-Ray Emission Spectra of Crystalline Carbon Nitride Films Deposited by Electron Cyclotron Resonance Sputtering
Authors: Muramatsu Yasuji , Tani Youji , Aoi Yoshifumi , Kamijo Eiji , Kaneyoshi Takahiro , Motoyama Muneyuki , Delaunay Jean J. , Hayashi Takayoshi , Grush Melissa M. , Callcott Thomas A. , Ederer David L. , Heske Clemens , Underwood James H. , Perera Rupert C. C.
Published: October 2002

The X-ray emission spectra of crystalline carbon nitride films deposited by electron-cyclotron-resonance (ECR) plasma sputtering were observed using a high-resolution soft X-ray
spectrometer at the Advanced Light Source to investigate the electronic structure of carbon nitride
crystals. The spectral features in C K and N K X-ray emissions from the ECR-deposited carbon
nitride films represent the highly degenerated valence orbitals and their highly pure crystalline form.
The C K and N K X-ray emission spectra were approximately explained based on the C2p and
N2p density of states in the hybridized C–N bonds. The absence of significant peak shifting in
selectively excited C K and N K X-ray emission spectra showed that there is a fairly nondispersive
structure between valence and conduction bands in ECR-deposited carbon nitride films.
Parallel Driving of Piezoelectric Transformers
Authors: Jeong Hoy-Seung , Choi Byung-Cheul , Yoo Ju-Hyun , Im In-Ho , Park Chang-Yup
Published: October 2002

Parallel driving of piezoelectric transformers has been
studied to increase output power, and output characteristics
of multiple piezoelectric transformers that are driven in
parallel from 2 to 5 have been compared to those of a
single transformer. The voltage step-up ratio increased in
proportion to the parallel connection number, n, but the rate
of increase decreased gradually, so there was little increase
with driving over 5 piezoelectric transformers in parallel. The
relative efficiency showed a maximum value of 1.06 with n of
2 and a minimum value of 0.75 with n of 5. The output
power increased continuously according to the parallel
connection number, but the relative output power per
transformer gave a value of 1.015 with n of 2 and decreased
to below 1.0 with greater n, so n of 5 gave a value of
0.75.
Preparation and Crystallization of Tin-doped and Undoped Amorphous Indium Oxide Films Deposited by Sputtering
Authors: Song Pung Keun , Akao Hirotaka , Kamei Masayuki , Shigesato Yuzo , Yasui Itaru
Published: October 2002

Tin-doped and undoped amorphous indium oxide films were prepared
by dc magnetron sputtering without substrate heating at relatively
high total gas pressures and relatively large target-substrate
distance. The structural and electrical properties of these films
were investigated by X-ray diffraction and Hall-effect measurements.
The amorphous tin-doped indium oxide (a-ITO) films were crystallized
at a temperature about 30°C higher than that for amorphous
indium oxide (a-IO) films.
Time Dependence of the Atomic Density in a Magneto-optical Trap
Authors: Ejnisman R. , Young Y. E. , Weiss S. B. , Bigelow N. P.
Published: October 2002

We have studied the evolution of the atomic density in magneto-optical traps. We have observed that the density increases according to (1-e
-t/ τn
), where the characteristic time τn may differ only slightly from the trap lifetime. We discuss the implications this has on the constant density approximation and solve the rate equation for trapped atom number in the case of a time-dependent density.
Low Temperature Growth of Epitaxial (Ba, Sr)TiO3 Thin Film by Sputter Molecular Beam Epitaxy Method
Authors: Horiguchi Atsushi , Watanabe Yukio
Published: October 2002

A novel sputtering method that can be regarded as a new version of the
molecular
beam epitaxy (MBE) method is proposed. Epitaxial (Ba,Sr)TiO3 films are grown
at a
pressure below 6×10-4 Torr at a large target-substrate distance of 24 cm.
The highest
temperature in all the deposition process including the in-situ post annealing is 350°C.
Additionally, a very smooth surface is confirmed by an atomic force microscopy.
Preparation of La-Modified Lead Titanate Film Capacitors and Influence of SrRuO3 Electrodes on the Electrical Properties
Authors: Nishida Takashi , Okamura Soichiro , Shiosaki Tadashi , Fujita Shigetaka , Masuda Yoichiro
Published: October 2002

SrRuO3 electrodes are expected to dramatically improve
the electrical properties of
PbTiO3 based ferroelectric film capacitors.
Because of the good ferroelectricity and pyroelectricity of La-modified lead titanate (PLT),
PLT film capacitors
with SrRuO3 and Pt electrodes were prepared.
The PLT and SrRuO3 films
were prepared by YAG(YAG) laser ablation.
YAG laser ablation has advantages over
the conventional excimer laser ablation
in running cost and safety.
The dependence of ablation conditions
on the composition and structure of PLT films
obtained by the YAG laser ablation
was revealed.
The electrical properties of the capacitor with SrRuO3
were compared with Pt.
As a result,
the low leakage current
was successfully obtained from the capacitors with
SrRuO3 electrodes.
Furthermore, little polarization fatigue
occurred in a SrRuO3/PLT/SrRuO3 capacitor
after 1010 switching cycles.
The electrical properties of the capacitors
with Pt and SrRuO3 top electrodes
are discussed.
The dielectric property, D-E hysteresis curves
and C-V characteristics were not affected by the top electrode material.
However, it was found that
the leakage current was significantly influenced by it.
The results can be explained on the basis of the Schottky barrier that formed at the interface between the top electrode and the PLT layer.
Based on these results,
the conduction mechanism in PLT thin-film capacitors
was investigated.
Effect of Pb Content on Electric Properties of Sol-Gel Derived Lead Zirconate Titanate Thin Films Prepared by Three-Step Heat-Treatment Process
Authors: Wang Zhan-jie , Maeda Ryutaro , Kikuchi Kaoru
Published: October 2002

Lead zirconate titanate (PZT) thin films were fabricated by a three-step heat-treatment process
which involves the addition of -10, 0 and 10 mol% excess Pb to the starting solution and spin
coating onto Pt/Ti/SiO2/Si substrates. Crystalline phases as well as preferred orientations in
PZT films were investigated by X-ray diffraction analysis (XRD). The microstructure and
composition of the films were studied by scanning electron microscopy (SEM) and electron
probe microanalysis (EPMA), respectively. The well-crystallized perovskite phase and the
(100) preferred orientation were obtained by adding 10% excess Pb to the starting solution. It
was found that PZT films to which of 10% excess Pb was added had better electric properties.
The remanent polarization and the coercive field of this film were 34.8 µC/cm2 and 41.7 kV/cm, while the dielectric constant and loss values measured at 1 kHz were approximately
1600 and 0.04, respectively. Dielectric and ferroelectric properties were correlated to the
microstructure of the films.
Growth Style of Bi4Ti3O12 Thin Films on CeO2/Ce0.12Zr0.88O2 Buffered Si Substrates
Authors: Migita Shinji , Uesugi Takumi , Kishi Hiroshi , Hirai Tadahiko , Sakai Shigeki , Tarui Yasuo
Published: October 2002

Epitaxial Bi4Ti3O12 thin films are grown on CeO2/Ce0.12Zr0.88O2 buffered Si(100)
substrates. The buffer consists of 40 Å Ce0.12Zr0.88O2 and 80 Å CeO2 layers which are
grown on Si(100) substrates by an e-beam evaporation method. Bi4Ti3O12 films are
grown by the molecular beam epitaxy method using the Bi self-limiting function.
Epitaxial growth of these layers on Si is confirmed by X-ray diffraction analyses.
Growth style of Bi4Ti3O12 films is examined in detail by observations of reflection high-energy electron diffraction and atomic force microscopy, and the growth mechanism is
discussed.
Microscopic Photoluminescence Study of InAs Single Quantum Dots Grown on (100) GaAs
Authors: Kazuya Asaoka Kazuya Asaoka , Yutaka Ohno Yutaka Ohno , Shigeru Kishimoto Shigeru Kishimoto , Takashi Mizutani Takashi Mizutani
Published: October 2002

We report ultranarrow (≤60 µeV) photoluminescence (PL) lines originating from single InAs quantum dots (QDs) sandwiched by Al0.35Ga0.65As barrier layers, demonstrating their δ-function-like density of states (DOS). The temperature dependence of the full-width at half maximum (FWHM) was studied between 10 and 90 K. It linearly increased with increasing temperature from 40 to 80 K (∼7 µeV/K), suggesting the existence of an excitonic dephasing mechanism. Pure dephasing of excitons due to exciton-phonon interactions in acoustic phonon mode was suggested as a possible mechanism for the PL line broadening.
Enhanced Piezoelectric Property of Barium Titanate Single Crystals with Engineered Domain Configurations
Authors: Wada Satoshi , Suzuki Shingo , Noma Tatsuo , Suzuki Takeyuki , Osada Minoru , Kakihana Masato , Park Seung-Eek , Cross L. Eric , Shrout Thomas R.
Published: October 2002

Piezoelectric properties of barium titanate single crystals were
investigated at room temperature as a function of crystallographic
orientation. When a unipolar electric field was applied along [001],
its strain vs electric-field curve showed a large hysteresis,
and finally barium titanate crystal became to single-domain state with
piezoelectric constant d
33 of 125 pC/N over 20 kV/cm. On the
other hand, electric-field exposure below 6 kV/cm along [111]
resulted in a high d
33 of 203 pC/N and a hysteresis-free strain
vs electric-field behavior, which suggested the formation of
an engineered domain configuration in a tetragonal barium titanate
crystal. Moreover, when an electric field over 6 kV/cm was applied
along [111], two discontinuous changes were observed in its strain
vs electric-field curve. In situ domain observation
and Raman measurement under an electric field suggested an
electric-field-induced phase transition from tetragonal to monoclinic
at around 10 kV/cm, and that from monoclinic to rhombohedral at
around 30 kV/cm. Moreover, in a monoclinic barium titanate crystal,
electric-field exposure along [111] resulted in the formation of
another new engineered domain configuration with d
33 of
295 pC/N.
Crystal Growth and Mechanical Properties of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 Single Crystal Produced by Solution Bridgman Method
Authors: Hosono Yasuharu , Harada Kouichi , Shimanuki Senji , Saitoh Shiroh , Yamashita Yohachi
Published: October 2002

High-quality, 40-mm-diameter piezoelectric Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 single crystals
(PZNT91/9) were successfully grown by the solution Bridgman method. Vickers hardness and
fracture toughness of a PZNT91/9 wafer cut from a crystal were investigated by a
microindentation technique. The Vickers hardness of PZNT91/9 was 2.6 GPa (transparent area)
and 2.2 GPa (opaque area). The Vickers hardness of the transparent area in PZNT91/9 was
equivalent to that of PZT ceramic. The fracture toughness of the transparent area of PZNT91/9
was markedly different depending on the domain direction: K
IC=0.80 MPa·m1/2 (vertical to the
domain wall); and K
IC=0.38 MPa·m1/2 (parallel to the domain wall). Although the fracture
toughness of PZNT91/9 is smaller than that of PZT ceramic, it is possible to cut the crystals for
fine-pitch dicing, as required to produce array-type medical
transducers, without serious problems.
Preparation of PbZrO3–PbTiO3–Pb(Mg1/3Nb2/3)O3 Thick Films by Screen Printing
Authors: Futakuchi Tomoaki , Matsui Yoshinari , Adachi Masatoshi
Published: October 2002

Ferroelectric Pb[Zr0.25T0.37(Mg1/3Nb2/3)0.38]O3 thick films were prepared by
a screen printing method on ZrO2 ceramic substrates over the
firing temperature range of 1100°C to 1300°C. The
microstructures, ferroelectric properties and electric
field-induced-strain properties of the thick films were examined in
comparison with bulk ceramics. A large remanent polarization of
33.0 µC/cm2 and a small coercive field of
6.5 kV/cm were obtained for the thick film fired at
1200°C. These values were comparable to those of bulk
ceramics.
Substrate-Dependent Microstructure and Magnetoresistance of La–Sr–Mn–O Thin Films Grown by RF Sputtering
Authors: Kyung-Ku Choi Kyung-Ku Choi , Yohtaro Yamazaki Yohtaro Yamazaki
Published: October 2002

The relationship between the microstructure and the magnetoresistive properties of La–Sr–Mn–O
thin films was investigated. La0.76Sr0.24Mn0.98O3-δ films were deposited onto (100)
SrTiO3, (100) LaAlO3, (110) sapphire and polycrystalline YSZ substrates by rf sputtering. The
films grew epitaxilly on SrTiO3 and LaAlO3 substrates with a large number of defects,
whereas in-plane-oriented and nonoriented polycrystalline films with 20–60 nm grains grew
on the sapphire and polycrystalline YSZ substrates, respectively. The magnetoresistance ratio
(H=0.8 T) of the epitaxial films has a peak at a temperature slightly below the maximum
resistance temperature. The resistivity of the epitaxial films was ten times less than that of the
polycrystalline films. The polycrystalline films exhibited substantial magnetoresistance ratios
over a wide temperature range. The existence of grain boundaries and the preferential in-plane
grain orientation were found to be correlated to the resistivity, temperature dependence and
low magnetic field sensitivity of magnetoresistance.
Temperature Dependent Surface Images of BaTiO3 Observed by Atomic Force Microscopy
Authors: Masaaki Takashige Masaaki Takashige , SinIchi Hamazaki SinIchi Hamazaki , Yoshio Takahashi Yoshio Takahashi , Fuminao Shimizu Fuminao Shimizu , Toshihisa Yamaguchi Toshihisa Yamaguchi
Published: October 2002

We used an atomic force microscope (AFM) to study the surface morphology of butterfly-like crystals of BaTiO3. Observations were made while varying the temperature from room temperature to 150°C and the annihilation process of the surface structure due to 90° domain boundaries was detected. The relationship between the surface gradient change at the domain boundaries and the tetragonal distortion was discussed.
Structure and Surface Properties of Metalorganic Vapor Phase Epitaxial CdTe and HgCdTe(111)B Layers Grown on Vicinal GaAs(100) Subatrates
Authors: Nishino Hironori , Murakami Satoshi , Nishijima Yoshito
Published: October 2002

We achieved the HgCdTe(111)B layer with a specular surface and high structural
quality, which was the candidate material for IRFPA application, on GaAs(100) by
metalorganic vapor phase epitaxy. To realize such superior layers, we studied the
structure and surface morphology of CdTe and HgCdTe(111)B with concerning the
growth mechanism. We found twins in CdTe were originated both at the CdTe–GaAs
interface and during the subsequent CdTe growth. These twins could be eliminated by
using misoriented substrates and adjusting the VI/II ratio conditions. Suitable
conditions for suppressing twins also improved the CdTe surface morphology. We
clarified the CdTe crystal perfection was improved effectively by decreasing the growth
rate. This attractive CdTe buffer was necessary for a twin-free HgCdTe(111)B layer
whose dislocation density was small. We obtained HgCdTe layers with good
structural quality and smooth surface morphology under the large VI/II ratio condition,
similar to the case of CdTe growth.
Investigation of Low-Temperature Deposition of Silicon Dioxide on Indium Phosphide by Liquid Phase Deposition
Authors: Wang Na-Fu , Houng Mau-Phon , Wang Yeong-Her
Published: October 2002

A new low-temperature process (35–45°C)for the deposition of high-quality silicon dioxide (SiO2) films on indium phosphide (InP) by liquid phase deposition (LPD) is proposed. The LPD-SiO2 film shows good, reliable quality in both physicochemical and electrical properties, which include a low effective net surface charge density per unit area (Q
SS/q=3.1×1011 cm-2), a small leakage current (6.64 pA, at -5 V), and a high dielectric breakdown strength (6.47 MV/cm), due to the lower deposition temperature.
Vibronic Fine Structure Found in the Blue Luminescence from Silicon Nanocolloids
Authors: Kimura Keisaku , Iwasaki Shingo
Published: October 2002

Well-isolated vibronic fine structures are observed on the
ultraviolet-visible photoluminescence spectrum from suspended silicon
nanometer-sized particles in an organic fluid. Progression analyses
of these structures and IR data show that these structures come from various local
vibrational modes that couple with the localized electronic state of
surface chemical species related to oxygen.
Desorption Kinetics of Ar Implanted into Si
Authors: Hirashita Norio
Published: October 2002

Thermal desorption spectroscopy and transmission electron microscopy were used to
study the desorption kinetics of Ar implanted into Si. The Si implanted with Ar ions at
the dose of 2×1015/cm2 under an acceleration energy of 60 kV exhibited two distinct
desorption states at temperatures of around 710°C and 1010°C, while Si samples
implanted with a lower Ar dose of 2×1014/cm2 did not show any distinct desorption
states. The first desorption state at the lower temperature was found to be associated
with solid phase epitaxial growth of the amorphous layer, and the second state at the
higher temperature is concomitant with the epitaxial realignment of microcrystalline Si
formed at low temperatures. The activation energies of desorption were evaluated to
be 2.35 and 3.91 eV, respectively, for the low-temperature and
high-temperature states.
Multiple Tunneling and Chaos in Asymmetrically Coupled Quantum Wells
Authors: Juang Cheng , Lee Gong Yee , Juang Jonq
Published: October 2002

Oscillatory and chaotic motion of heavy to light hole mixing tunneling in asymmetrically coupled quantum well structures is determined by two competing processes: HH
a
to LH
a
and HH
a
to LH
b
. Chaotic behavior occurs if the two processes are compatible. Oscillatory motion is recovered if one process is dominant. The effects of barrier width, external field, and in-plane wave factor k
∥ on each process are addressed.
A Multilevel Interconnect Technology with Intrametal Air Gap for High-Performance 0.25-µm-and-Beyond Devices Manufacturing
Authors: Lin Mark , Chang Chun Yen , Huang Tiao Yuan , Lin Mout-Lim
Published: October 2002

A multilevel interconnect technology with an intra metal air gap
has been developed to reduce the interconnect delay time for
versatile, and quick turnaround-time foundry manufacturing. The
air-gap method has been successfully applied to 0.25 µm IC
technology and shown to be effective in reducing the parasitic
interconnect capacitance. Measurements of various ring oscillators
confirm that the smallest delay time is indeed achieved with the
air-gap method, compared with other methods using either conventional
high-density-plasma (HDP) oxide or low-dielectric-constant
spin-on-glass (SOG) as the gap-filling insulating materials. Moreover,
the oscillator delay time is found to depend critically on not only
the size of the air gap, but also the position of the air gap. Best
results in terms of delay time reduction are obtained when the air-gap
is positioned in the middle between the two metal lines, and extends
both above and below the metal lines to effectively reduce the
fringing capacitance. We have also measured the leakage current
between adjacent metal lines and confirmed that our new metal
interconnect structure with an air gap does not exhibit any
appreciable leakage and appears to be suitable for high-performance
foundry applications. Lastly, the polarization and thermal
characteristics of the air-gap structure were compared with
conventional gap-filling methods.
Preparation of SrBi2Ta2O9 Thin Films by Liquid-Delivery Metalorganic Chemical Vapor Deposition using a Double Alcoholate Source
Authors: Takehito Jimbo Takehito Jimbo , Haruyuki Sano Haruyuki Sano , Yuji Takahashi Yuji Takahashi , Hiroshi Funakubo Hiroshi Funakubo , Eisuke Tokumitsu Eisuke Tokumitsu , Hiroshi Ishiwara Hiroshi Ishiwara
Published: October 2002

A liquid-delivery metalorganic chemical vapor deposition (MOCVD) apparatus for preparing SrBi2Ta2O9 (SBT) thin films was designed and set up. For the preparation of SBT thin films, a double alcoholate source, Sr[Ta(OC2H5)6]2, was used for supplying Sr and Ta atoms with a stoichiometric composition, while Bi(C6H5)3 was used for supplying Bi atoms. In the experiment, variation of the film composition with the deposition temperature and source-supply mol ratio was primarily investigated. It was found that the Bi/Ta mol ratio in the films varied with the deposition temperature and became smaller at lower deposition temperatures. It was also found that the Sr/Ta mol ratio was considerably smaller than stoichiometry above 500°C, probably because of the dissociation of Sr[Ta(OC2H5)6]2. It was ascertained that a 200-nm-thick SBT thin film with the Sr/Ta mol ratio of about 0.4, which was deposited at 350°C and subsequently annealed in O2 atmosphere at 750°C for 30 min, exhibited ferroelectricity. The dielectric constant of the film was about 120. Remanent polarization and coercive field at 10 V were 3.8 µC/cm2 and 73 kV/cm, respectively. However, the leakage current density was found to be as high as the order of 10-4 A/cm2 at 3 V. It is speculated from atomic force microscope (AFM) observation of the surface roughness of the film that the origin of the high leakage current density is the existence of local high electric field spots in the film.
Chemical Dry Etching of Si Substrate in a Discharge Flow Using Ar/CF4 Gas Mixtures
Authors: Masaharu Tsuji Masaharu Tsuji , Shinji Okano Shinji Okano , Atsushi Tanaka Atsushi Tanaka , Yukio Nishimura Yukio Nishimura
Published: October 2002

F atoms were generated by a low-power microwave discharge of various Ar/CF4 mixtures in a fast discharge flow. They were used for chemical dry etching of Si substrate at room temperature. The variation of etch rate was measured as a function of the microwave power, the Ar or CF4 flow rate, and the distance between the center of discharge and the substrate, in order to determine the optimum conditions. The maximum etch rate was about 700 Å/min at a microwave power of 80 W, an Ar flow rate of 3000 sccm, a CF4 flow rate of 70 sccm, and a distance between the center of discharge and the substrate of 10 cm. A thin CmFn polymer was deposited on the etching edge at high CF4 flow rates of 80–100 sccm.
Growth of Four-fold Grained K3Li2Nb5O15 Thin Film Using RF-Magnetron Sputtering
Authors: Park Sung-Kun , Baek Min-Soo , Bae Seoung-Choon , Kwon Sung-Yeol , Kim Jee-Hyun , Kim Ki-Wan
Published: October 2002

K3Li2Nb5O15 (KLN) thin films were prepared
using an rf-magnetron sputtering technique with a sintered ceramic
target containing 60 mol% and 30 mol% excess K and Li, compared
with stoichiometric KLN, respectively. In this experiment the optimum
sputtering conditions were an rf power of 100 W, a working pressure
of 150 mTorr, and a substrate temperature of 600°C. When
KLN was grown on a Pt/Ti/SiO2/Si(100) substrate at a temperature of
600°C with 150 mTorr, the thin film KLN was (001)-oriented
with diffraction peaks from the (311) plane. The re-vaporization of
the volatile element on the substrate was successfully suppressed by
increasing the sputtering pressure. In this work 4-fold grains of KLN
thin film and the growth mechanism of 4-fold symmetric grains were
both observed for the first time.
An Allene-Doped Liquid Argon Ionization Chamber for O and Ne Ions at 100 MeV/n
Authors: Yunoki Akira , Doke Tadayoshi , Kase Masayuki , Kashiwagi Toshisuke , Kato Toshiyuki , Kikuchi Jun , Masuda Kimiaki , Niimura Masanobu , Ozaki Kiminori , Shibamura Eido , Tanaka Motoyuki , Tanihata Isao
Published: October 2002

An allene-doped liquid argon ionization chamber with a sensitive
volume of 48 mm×48 mm×40 mm has been
constructed and investigated for precise measurement of the heavy ion
energies at around 100 MeV/n. An energy resolution of 1% (full
width at half maximum [FWHM]) was achieved for the 99 MeV/n 16O
and 125 MeV/n 20Ne ion beams. However, the energy resolution
was found to deteriorate as the beam intensity increased. To
understand this phenomenon, a simple model is proposed, in which a
space-charge electric field due to the positive ions left along the
track of an incident ion is taken into consideration. The estimated
electric field is strong enough to worsen the energy resolution when
the incident beam intensity is only 100 particles/s.
Phase-Shifting X-Ray Shearing Interferometer
Authors: Iwata Koichi , Kikuta Hisao , Tadano Hiroyuki , Hagino Hideki , Nakano Takashi
Published: October 2002

We propose an X-ray shearing interferometer, where two slightly sheared X-ray beams are
produced, both of which are transmitted through an object. The two beams are superposed
and interfere after they are transmitted through the interferometer. The interfered beams
show intensity variation due to the phase difference between the sheared beams. To measure
the phase difference, the phase-shift method is introduced. To obtain the phase shift, an
acrylic wedge is rotated. This interferometer is constructed by monolithical cutting from a
single silicon crystal. The phase difference distribution along a line is obtained by detecting
the X-ray intensity at a point and scanning the objects mechanically. Some simple objects
made of acrylic resin are measured with good contrast, showing the validity of the interferometer.
Application of Monte Carlo Simulation to Structural Analysis by Soft X-Ray Emission Spectroscopy for a Silicide/Si-Bulk System
Authors: Kinoshita Akimasa , Hirai Masaaki , Kusaka Masahiko , Iwami Motohiro
Published: October 2002

A Monte-Carlo (MC) simulation is applied to the quantitative
microanalysis of a film/substrate system. The characteristic X-ray
intensity is used in this simulation. However, it is difficult to
determine the film thickness for a multilayer/substrate system which
consists of two elements in this method using characteristic X-ray
intensity only. In order to overcome this difficulty, we utilized the
characteristic Si–L2,3 soft X-ray emission band spectra which
have their own spectral shapes for silicides and Si, and are expected
to be superior to the conventional method using band X-rays only. In
the measurement of the Si–L2,3 spectrum for a silicide/Si system
at a certain incident energy, the obtained Si–L2,3 spectrum
exhibits the increasing characteristic of the film material spectrum
with the increase in film thickness. By using this characteristic,
quantitative analysis using both MC simulation and Si–L2,3
emission band spectra is demonstrated for the CoSi2/Si system in
this study.
Fabrication of Solar Cells Having SiH2Cl2 Based I-Layer Materials
Authors: Shimizu Satoshi , Komaru Takashi , Okawa Kojiro , Azuma Masanobu , Kamiya Toshio , Fortmann Charles M. , Shimizu Isamu
Published: October 2002

Intrinsic amorphous silicon films were fabricated using electron
cyclotron resonance (ECR) assisted chemical vapor deposition and
SiH2Cl2 source gas. Intrinsic layers were used for material
characterization and also for the absorber layer of solar cells. The
highly reducing atmosphere produced by the high energy ECR hydrogen
plasma used to deposit these intrinsic films caused some degradation
and/or etching of the previously deposited solar cell doped layers as
well as the SnO2-coated glass substrates. The p-layer etching rates
were greater than those of the n-layer when these layers were exposed
to ECR hydrogen plasma. Optimum photovoltaic performance was achieved
when an optimized n/i interfacial buffer layer was used for a solar
cell deposited in the n-i-p sequence. Better solar cell performances
were obtained when the solar cells were measured under n-side
illumination. In part, the buffer layer optimization involved careful
consideration of band gap matching to the relatively wide band gap
(1.85 eV) intrinsic layers prepared from SiH2Cl2. Further performance
gains were possible through transparent conductive oxide/substrate
optimization. For example, the open circuit voltage (V
oc)
increased to ∼0.89 V when gallium-doped zinc oxide/glass substrates were used
compared to ∼0.63 V when tin oxide/glass substrates were
used. Interface recombination and minority carrier diffusion lengths
were probed by n- and p-side illuminated quantum efficiency
measurement and analysis. The electron and hole µτ products were
estimated to be 4.4×10-8 cm2/V and 3.5×10-8 cm2/V, respectively. The
stability of the solar cells was also examined.