bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of Power Absorption in a Modified Magnetron-type Discharge
Authors: Wickramanayaka Sunil , Takagi Ken-ichi , Nakagawa Yukito , Sato Tsutomu Tsukada
Published: October 2002

The power absorption of a modified magnetron-type discharge that has a cylindrical shaped rf electrode is estimated using two different independent methods. The experiment was carried out for the rf power up to 500 W at a frequency of 13.56 MHz and for the pressure region of 0.5 mTorr to 10 mTorr. This magnetron-type plasma shows a higher power transfer efficiency (η) around 75% in the pressure region of 0.5 mTorr to 10 mTorr. With an increase of the pressure or applied rf power, the η tends to drop. For comparison, the η in the absence of the magnetic field is also estimated and reported. In the absence of the magnetic field, the η of the plasma source drops to about 30% at 2 mTorr.
Properties of Light-Emitting Diodes Fabricated from Self-Assembled Multilayer Heterostructures of Poly(p-pyridyl vinylene)
Authors: Onoda Mitsuyoshi , Nakayama Hiroshi , Yamaue Takahiro , Tada Kazuya , Yoshino Katsumi
Published: October 2002

Hetrostructure multilayer thin films of electroactive polymers such as protonated poly(p-pyridyl vinylene), PHPyV, and sulfonated polyaniline, SPAn, have been successfully fabricated via a process based on the spontaneous self-assembly of conjugated polyions on a substrate. The heterostructure thin films formed by these different polymers exhibited a perfectly linear relationship between the absorbance and the number of a SPAn/PHPyV bilayer, SPAn/PHPyV(b), deposited. A greenish-yellow electroluminescent (EL) diode utilizing an SPAn/PHPyV multilayer thin film, SPAn/PHPyV(m), has been produced, and the EL properties of this device are discussed. The EL emission of this device can be qualitatively interpreted in terms of a radiative recombination of the singlet polaron exciton formed by the injection of electrons and holes. The EL intensity of this light-emitting diode is weak. This result is discussed in terms of the quenching centers associated with cationic sites on PHPyV polymer main chain at the heterojunction. The Stokes shift due to the absorption and emission of a phonon is clearly observed in the EL spectrum of this device. A small shift between the EL and PL spectra of SPAn/PHPyV(m) is observed. It was assumed that the EL emission takes place in a narrow region at the interface while the PL emission probes the bulk of the film. The SPAn/PHPyV(b) (LED) emits yellow light, but SPAn/PHPyV(m) emits greenish-yellow light, and there is a slight shift between the two spectra of these devices. These results can be interpreted in terms of the confinement effect of carriers in the superlattice structure of the SPAn/PHPyV (m) system.
Ozone Generation by Positive and Negative Wire-to-Plate Streamer Discharges
Authors: Frank Hegeler Frank Hegeler , Hidenori Akiyama Hidenori Akiyama
Published: October 2002

A UV absorption technique is used to investigate the ozone generation after a positive or negative streamer discharge in air at atmospheric pressure. The discharge apparatus consists of a 45 cm long wire-to-plate configuration with an electrode gap distance of 2.5 cm. After either positive or negative streamer discharges, the highest ozone density occurs in an area just below the wire electrode. Towards the ground plate, the ozone density decreases rapidly. Positive streamer discharges produce about twice as much ozone density as negative streamer discharges with the same pulse duration.
Non-Destructive Characterization of InGaAsP/InP Distributed Bragg Reflectors and Regrown Optical Cavity Layers for InP-Based Vertical-Cavity Surface-Emitting Lasers
Authors: Okamoto Hiroshi , Tadokoro Takashi , Yasuhiro Kondo Yasuhiro Kondo , Masashi Nakao Masashi Nakao
Published: October 2002

A non-destructive characterization method for epitaxial wafers of vertical-cavity surface-emitting laser (VCSEL) before device processing, and a way for reproducible fabrication of the distributed Bragg reflector (DBR) using this method, are discussed. The DBR, active layer, and cavity length are successfully characterized by using YAG-laser-excited PL measurement and reflectivity-spectrum measurement. For a buried-heterostructure VCSEL, cavity length is evaluated by using a newly assembled small-area-spectral-reflectance measurement system. It is also shown that the cavity length can be tuned by using chemical etching.
Pd–Ge–Au Based Hybrid Ohmic Contacts to High-Low Doped GaAs Field-Effect Transistor
Authors: Kwak Joon Seop , Lee Jong-Lam , Hong Koo Baik Hong Koo Baik
Published: October 2002

Effects of an intermediate layer, such as Mo or Ti, have been studied for developing Pd–Ge–Au based hybrid ohmic contacts in a high-low doped GaAs metal-semiconductor field-effect transistor (MESFET). The Pd–Ge–Au contact without the intermediate layer produces an alloyed AuGe contact at a high annealing temperature above 400° C. When Mo is added between Pd/Ge and Au, nonspiking Pd/Ge contact is formed at a low annealing temperature of 300° C. The addition of Ti, however, results in an ohmic contact with a low resistance of 0.43 Ω· mm in a wide annealing temperature ranging from 340 to 420° C. Auger depth profile and X-ray diffraction results suggest that the low resistance of the Pd/Ge/Ti/Au ohmic contact is due to formation both the Pd/Ge contact and AuGe contact through the appropriate control of Au indiffusion by Ti. The MESFET with the Pd/Ge/Ti/Au contact displays good DC characteristics. This supports that the Pd/Ge/Ti/Au contact is well suitable for application to high-low doped GaAs MESFETs due to its low-resistance and wide-process-window.
Video Disk Recorder System Using Magneto-Optical Disk
Authors: Murata Seiji , Asano Kenji , Mamiya Noboru , Suzuki Yoshihisa , Takahashi Seiichirou , Kunisa Akiomi , Nobuo Itou Nobuo Itou , Kenji Torazawa Kenji Torazawa
Published: October 2002

We have developed a video disk recorder system using a magnetically induced super resolution (MSR) magneto-optical (MO) disk 120 mm in diameter and achieved a user data capacity of 4.1 Gbytes per disk using land/groove recording technology, a laser wavelength of 685 nm, and (1, 7) run-length limited (RLL) code. In this case, track pitch is 0.7 µm and minimum mark length is 0.4 µm. The system can record 125 minutes of moving images encoded using the MPEG2 method. In this paper we describe our high-density magneto-optical recording technology and the video disk recorder system which incorporates magnetic field modulation.
Liquid-Phase Epitaxial Growth of In0.35Ga0.65P on GaP Substrates from Sn-Rich Solutions
Authors: Lung-Chien Chen Lung-Chien Chen , Meng-Chyi Wu Meng-Chyi Wu
Published: October 2002

Good-quality In0.35Ga0.65P layers have been grown on (111)B-oriented GaP substrates by liquid-phase epitaxy from Sn-rich solutions using the supercooling technique. The InGaP epitaxial layers exhibit a mirrior-like surface morphology and a flat interface without any inclusions. The growth rate of InGaP layers grown from Sn-rich solutions is found to be considerably lower than that from In-rich solutions. The minimum electron concentration of 1.1×1018 cm-3 obtained is attributed to the Sn-doped epitaxial layer grown from the Sn-rich solution. Three emission peaks in photoluminescence spectra of the InGaP layers are indentified as the near band-to-band, donor-to-valence band, and donor-acceptor pair transitions. In addition, the InGaP/GaP sample has a good interface examined by high resolution transmission electron microscope.
Thermal Conductivity and Diffusivity of High-Strength Polymer Fibers
Authors: Fujishiro Hiroyuki , Ikebe Manabu , Kashima Toshihiro , Yamanaka Atsuhiko
Published: October 2002

The thermal conductivity κ and diffusivity α of high-strength and high-modulus crystalline polymer fibers (polybenzobisoxazole (Zylon\circR) and polyethylene (Dyneema\circR)) and their fiber-reinforced plastics (FRPs) were measured in directions parallel and perpendicular to the molecular chain axis of the fibers. The main contribution to thermal conductivity was from phonon conduction along the molecular chains in both fibers and the phonon conduction was limited by boundary-like scattering over the temperature range of 10–260 K. From the analyses using a phenomenological model, the thermal conductivity anisotropy ratio (κ//
fiber/κ⊥
fiber) of Zylon fiber was estimated to be 80 at 100 K, which was about two or three times larger than that of Dyneema fiber.
Fabrication and Characterization of CdS Nanostructure Doped Glass Thin Films by Pulsed Laser Evaporation
Authors: Sun-Bin Yin Sun-Bin Yin , Wen-Feng Hsieh Wen-Feng Hsieh
Published: October 2002

CdS doped glass thin films were grown by pulsed laser evaporation from sol–gel prepared targets. The sol–gel process was carried out under basic catalysis to contain more CdS dopants than those acid catalyzed. The structure of the CdS nanocrystallites in the film is determined to be wurzite by X-ray diffraction. The blue shift of the absorption edge and photoluminescence spectra, as well as the softening of the longitudinal optical phonon Raman mode, exhibit a quantum size effect. The diameter of CdS clusters embedded in the glass film is measured by these spectra to be 300 Å. The composition of the film determined by an electron probe microanalyzer and energy-dispersive spectrometer indicates that the amount of S atoms is greater than that of Cd atoms.
Characterization of Ba1-XSrXWO4 Solid-Solution Films Prepared by an Electrochemical Method at Room Temperature
Authors: Woo-Seok Cho Woo-Seok Cho , Masahiro Yoshimura Masahiro Yoshimura
Published: October 2002

Films of a complete series of solid-solution oxides, Ba1-
X

Sr

X

WO4 (0≤X≤1), have been prepared on tungsten substrates in an electrolytic solution containing Ba2+ and Sr2+ ions by an electrochemical method at room temperature (25° C). X-ray diffraction and X-ray photoelectron spectroscopy analyses showed that a complete series of well-crystallized solid-solution oxides was formed even at room temperature. The Ba-to-Sr ratio in these films was larger than that in the starting solutions. Sr-rich films (X≥0.7) showed only blue emission at liquid-nitrogen temperature (-196° C), however, the other films did not luminesce at this temperature.
Effect of Activation of Oxygen by Electron Cyclotron Resonance Plasma on the Incorporation of Pb in the Deposition of Pb(Zr,Ti)O 3 Films by DC Magnetron Reactive Sputtering
Authors: Sung-Tae Kim Sung-Tae Kim , Hyun-Ho Kim Hyun-Ho Kim , Yong-Il Kim Yong-Il Kim , Moon-Yong Lee Moon-Yong Lee , Won-Jong Lee Won-Jong Lee
Published: October 2002

Pb(Zr,Ti)O3 films were deposited by DC magnetron reactive sputtering on Pt/Ti/SiO2/Si and Pt/SiO2/Si substrates. The activation of oxygen by electron cyclotron resonance (ECR) plasma facilitated the incorporation of Pb. This enabled the fabrication of Pb(Zr,Ti)O3 films with stoichiometric composition and perovskite structure even at a high Zr/Ti film concentration ratio and high substrate temperature and on Pt/SiO2/Si substrates where the pyrochlore second phase was usually observed when the films were deposited without oxygen activation.
Difference in Diffusion Length of Ga Atoms under As2 and As4 Flux in Molecular Beam Epitaxy
Authors: Sugaya Takeyoshi , Nakagawa Tadashi , Sugiyama Yoshinobu , Tanuma Yasuhiko , Yonei Kenji
Published: October 2002

The surface diffusion length of Ga adatoms under As2 or As4 flux has been measured using V-grooved GaAs (001) substrates in molecular beam epitaxy. The diffusion length on the (001) surface toward the [110] direction, of Ga adatoms under As2 flux is about half of that under As4 flux. A smaller number of Ga atoms under As2 flux migrate to the (001) ridge surface from the sidewall surface than those under As4 flux. Furthermore, the Al0.6Ga0.4As layer on the V-grooved GaAs substrate grown under As2 flux preserve the V-shape, whereas the V-shape cannot be preserved during the growth under As4 flux. The GaAs quantum wire structures which have Al0.6Ga0.4As barrier layeres are fabricated under As2 flux.
Photosensitive Materials on a Base of Polysiloxane for the Alignment of Nematic Liquid Crystals
Authors: Yaroshchuk Oleg , Pelzl Gerhard , Pirwitz Grit , Reznikov Yuriy , Zaschke Horst , Kim Jong-Hyun , Kwon Soon Bum
Published: October 2002

The light-induced alignment of a number of commercial liquid crystals (LC) on the surface of photosensitive polysiloxane based polymers was studied. It was shown that the materials can provide thermostable homeotropic, planar and tilted alignments of good quality. The value of tilt angle depends upon the LC material, irradiation intensity and exposure as well as aligning film thickness and temperature treatment.
Ce-doped TiO 2 Insulators in Thin Film Electroluminescent Devices
Authors: Prasad Kshem , Bally Alain R. , Schmid Philippe E. , Lévy Francis , Benoit Jacques , Barthou Carlos , Benalloul Paul
Published: October 2002

Cerium-doped TiO2 thin films have been prepared by reactive RF sputtering. At low Ce concentration, X-ray diffraction indicates that the films have the anatase structure. Ce concentrations higher than 1.2 at.% result in an amorphization of the film which remains stable up to 873 K. The TiO2 electrical properties have been stabilized and improved by cerium doping, resulting in a lower conductivity (10-9 Ω-1m-1), a higher electrical breakdown strength (2 ×107 V/m), and a high value of the permittivity (45±5). The implementation of amorphous TiO2:Ce thin films as insulator layers in ZnS:Mn alternating current thin film electroluminescent devices (ACTFELD) results in a significant drop in the threshold operating voltage and a notable increase in the device brightness compared with ACTFELD containing Y2O3 or BaTa2O6 insulator layers. Rapid thermal annealing further improves the performance of the electroluminescent device.
All-solid-state Electrochromic Window of Electrodeposited WO3 and Prussian Blue with Poly(ethylene oxide) Gel Electrolyte
Authors: Su Lianyong , Jinghuai Fang Jinghuai Fang , Zuhong Lu Zuhong Lu
Published: October 2002

An all-solid-state electrochromic window (SEW) employing electrodeposited WO3 and prussian blue with polymer gel electrolyte has been fabricated. The conductivity of poly(ethylene oxide) (PEO)-based gel electrolyte was 4.6×10-4 S/cm at room temperature. The W 4f core level spectra of WO3 film at different levels of coloration have been investigated using XPS. W 4f peaks become broader after coloration. The SEW has been found to have excellent electrochromism and memory characteristics. A reversible color change between blue and colorless was observed when an appropriate potential was applied repeatedly to the electrochromic window.
Low Voltage Lead Zirconate Titanate (PZT) and Lead Niobate Zirconate Titanate (PNZT) Hysteresis Loops
Authors: Boyer Leonard L. , Evans Naomi Velasquez , Jr. Jr.
Published: October 2002

A major emerging market for ferroelectric non-volatile memories is the RF tag. In that application, low power and low voltage memory operation is essential. Historically, the
lead zirconate titanate (PZT) family has not been noted for low voltage hysteresis loops but this is a function of process and not a property
of the material. The authors have reduced the saturation voltage for a PZT sol gel process to less than 2.5 V while achieving greater than
40 µ C/cm2 δP for 20/80 PZT using platinum electrodes. Niobium doped PZT has also been fabricated with the low saturation
voltage while producing greater than 30 µ C/cm2 δP. The authors report on the electrical properties of these films.
Low-Temperature Processing of Highly Oriented Pb(ZrXTi1-X)O3 Thin Film with Multi-Seeding Layers
Authors: Suzuki Hisao , Kaneko Shoji , Murakami Kenji , Hayashi Takashi
Published: October 2002

An improved sol-gel process using molecular-designed alkoxide precursor was
described for a lead zirconate titanate (PZT) thin film. This method involves the insertion of
inter-layer films of a perovskite lead titanate (PT) layer as a transient seeding layer between
each PZT layers, which offers nucleation sites to reduce the activation energy for the
crystallization, leading to the low processing temperature (hereafter, abbreviated as a multi-seeding
process). An intermediate pyrochlore phase developed in the film by annealing at
around 400° C in an air, and then was completely converted to a perovskite phase at a low
temperature of 450° C. The relative permittivity of the resulting film annealed at 450° C
increased with increasing film thickness and reached about 350 at 1.9 µ m. In addition, highly
oriented PZT film was obtained by annealing at 500° C for 2 hours in an air. This highly
oriented film exhibited high relative permittivity of about 500 due to its microstructure. As a
result, it was demonstrated that multi-seeding process was desirable for obtaining a single
phase perovskite PZT film at low temperatures.
Grating Polarizing Beam-Splitter Using Polymerized Liquid Crystal
Authors: Sato Hiromasa , Hotaka Hiroki , Gunjima Tomoki , Yuzuru Tanabe Yuzuru Tanabe , Masahiro Hirano Masahiro Hirano
Published: October 2002

A grating polarizing beam-splitter was developed using a newly synthesized UV curable liquid crystal. The fabricated device shows high diffraction efficiency (+1st order: 35.5%, -1st order: 31.9%) and transmittance (83.8%). The temperature dependence of diffraction efficiency variation was suppressed by about 5% within temperature range from 20 to 80°C because these device parameters become less sensitive to temperature variation as a result of photopolymerization.
Preparation and Basic Properties of SrBi 2Ta 2O 9 Films
Authors: Yoshihiro Oishi Yoshihiro Oishi , Yoshinori Matsumuro Yoshinori Matsumuro , Masanori Okuyama Masanori Okuyama
Published: October 2002

Ferroelectric SrBi2Ta2O9 thin films have been prepared on Pt and SiO2/n-Si(100) by laser ablation using an ArF excimer laser below 560°C.
Crystallographic properties of the films are characterized as a function of substrate temperature and ambient pressure.
Preferentially (105)-oriented SrBi2Ta2O9 thin films are obtained on SiO2/Si and Pt sheets.
D–E hysteresis loops are observed in SrBi2Ta2O9 thin films deposited on Pt sheets. The remnant polarization is 2.5 µC/cm2 and the coercive force is 34 kV/cm.
The films deposited on SiO2/Si consist of grains about 100 nm in diameter. Depth profiles from X-ray photoelectron spectra reveal homogeneous compositions, and the elements of the film diffuse little at the interface between the SrBi2Ta2O9 thin film and SiO2.
The energy distributions of the density of interface states are below 1012 cm-2eV-1 in SiO2/Si at 550°C and below 3×1011 cm-2eV-1 at 400°C.
A good capacitance-voltage hysteresis curve is obtained in the metal-ferroelectric-oxide-semiconductor structure using the SrBi2Ta2O9 film on SiO2/Si at T
s of 550°C.
Preparation and Dielectric Properties of SrBi2Ta2O9 Thin Films by Sol-Gel Method
Authors: Hayashi Takashi , Takuya Hara Takuya Hara , Hiroshi Takahashi Hiroshi Takahashi
Published: October 2002

Ferroelectric Sr0.7Bi2.2Ta2O9 (SBT) thin films were prepared on Pt/Ti/SiO2/Si substrates at
800° C by sol-gel method. The means of preparation of solutions of SBT precursors and the addition of acetylacetone to
the alkoxides affected the crystal orientation and the microstructure of the films. The (00 l ) preferred orientation
degree of SBT thin films varied from 0 to 80%. Thin films of SBT with a highly preferred (00 l ) orientation exhibited
grain structure resembling a stone wall, while those randomly-oriented with a high (105) diffraction intensity exhibited a
rod-like grain structure. The SBT thin films with a random orientation exhibited values of ε
r of 90, P
r of
6.5 µ C/cm2 and E
c of 80 kV/cm, while those with a (00 l ) orientation degree of 80% exhibited values
of ε
r of 78, P
r of 1.6 µ C/cm2 and E
c of 110 kV/cm. The (00 l ) preferred orientation
was associated with the deterioration of ferroelectric properties.
Role of Excess Bi in SrBi2Ta2O9 Thin Film Prepared Using Chemical Liquid Deposition and Sol-Gel Method
Authors: Koiwa Ichiro , Okada Yukihisa , Mita Juro , Hashimoto Akira , Sawada Yoshihiro
Published: October 2002

We studied the role of excess Bi, added to improve ferroelectirc properties of
SrBi2Ta2O9 (SBT) thin film whose Bi-layered structure is fatigue-free characteristics for
Nonvolatile memory. The lost of Bi by annealing process was not observed even after
annealing at 850° C in chemical liquid deposition (mixed alkoxide solution system). In
SBT films composed of fluorite and Bi-layered structure grains, Bi-layered structure
grains had a higher Bi content than that in fluorite grains. Excess Bi was added to
promote crystallization of fluorite to the Bi-layered structure easy. SBT film close to
stoichimometric composition formed by a hydrolyzed, condensed solution (sol-gel
method) had superior ferroelectric properties despite its closely stoichiometric
Sr0.9Bi2.1Ta2O9 composition. Closely stoichiometric Sr0.9Bi2.1Ta2O9 SBT film shows
no fatigue even after 3×1012 switching cycles. The improved SBT formation solution
that is hydrolyzed, condensed solution makes excess Bi unnecessary.
Effects of Polarization Reversal and Surface Conditions on the Ferroelectric Electron Emission
Authors: Miyake Masatoshi , Ibuka Sinji , Koichi Yasuoka Koichi Yasuoka , Shozo Ishii Shozo Ishii
Published: October 2002

The electron emission from ferroelectric ceramics has been observed without
prepoling. The grid electrodes and the solid electrode are coated on the top and the
bottom of a thin lead-zirconate-titanate (PZT) ceramic plate, respectively. The
ratio of the interelectrode width to the thickness of the ceramic determines the
potential distribution inside the ceramic. With an appropriate ratio, the
polarization can be reversed between the grid electrodes. The prepoled PZT
ceramic was not essential for the electron emission, because the shape of the
waveform of the emission current after prepoling is nearly the same as that
obtained without prepoling. However, the peak value of the emission current
depends to a large extent on the polarities of the spontaneous polarization and the
applied electric field. In addition, the surface condition such as microcracking is as
crucial as polarization reversal for the electron emission.
Crystal Growth of Lead Zirconate Titanate with Additives under Hydrothermal Conditions
Authors: Kanai Kazumichi Yanagisawa
Published: October 2002

Single crystals of lead zirconate titanate (PZT) with an additive such as La2O3, Nb2O3 or MnO were
grown under hydrothermal conditions with the starting nutrient of PZT ceramic powder based on Pb(Zr0.53Ti0.47)O3.
The powder placed at the bottom of the capsule was dissolved in the KF solution at 640° C, and recrystallized at the
top of the capsule at 600° C. Large crystals up to 1.8 mm in length were grown in 45 wt% KF solution, but a decrease
in the concentration resulted in the reduction of the volume and size of the grown crystals. The addition of Nb to PZT ceramics
inhibited the growth of the crystals. The additives in the starting materials were incorporated into the grown crystals, but
the concentration of Zr in the crystals was markedly reduced in comparison with that of the starting materials.
Crystal Growth and Electrical Properties of Lead Scandium Niobate-Lead Titanate Binary Single Crystals
Authors: Yohachi Yamashita Yohachi Yamashita , Kouichi Harada Kouichi Harada
Published: October 2002

Single crystal preparations of the
Pb[(Sc1/2Nb1/2)1-
X

Ti

X

]O3 binary system have been
investigated by a flux method using 75 mol%PbO-25 mol%B2O3 flux. The crystals were grown in a
platinum crucible by mass crystallization, achieved by slow-cooling the solution at 1° C/h from
1,200° C to 880° C.
The resulting crystals were 2–15 mm in length. Chemical analysis and X-ray
studies revealed that the crystals are of the perovskite structure with x=0.33 to 0.35, making them
slightly different from the charged morphotropic phase boundary composition of x-0.42. The (001)
single crystal showed a dielectric constant peak of 60,000 at 206° C. The crystal has a remnant
polarization P
r=26 µ C/cm2, a coercive field E
c=6 kv/cm,
a room temperature dielectric constant after
poling ε
33
τ/ε
0=960, a dielectric loss of 0.5%,
and an electromechanical coupling factor k
33=72%.
Ultrasonic Properties of Lead Zirconate Titanate Thin Films in UHF-SHF Range
Authors: Hanajima Naoyuki , Tsutsumi Shuji , Yonezawa Tadashi , Hashimoto Kenya , Yamaguchi Ryota Nanjo
Published: October 2002

We describe the ultrasonic properties of lead zirconate titanate (PZT) thin films
prepared by the sol-gel method. It is shown that the PZT thin film exhibits efficient
transduction of bulk and surface acoustic waves in UHF-SHF range. A conversion
loss of less than 4 dB is achieved for bulk wave excitation and detection at 1.7 GHz,
where the electromechanical coupling factor k
t reaches 30%. This indicates that the
PZT thin film is promising for use in the development of large-bandwidth resonators
and filters in modern communication systems as well as for high-frequency
ultrasonic transducer applications.
Electronic Structures and Dielectric Properties of Substituted BaTiO3
Authors: Sugihara Sunao , Yonekura Isaku , Sekine Hideto Kurahashi
Published: October 2002

Electronic structures were investigated on BaTiO3 substituted with other
elements, such as Ca, Sr, Sc, Y, Ce and Gd for Ba, using a molecular orbital
treatment that yielded net charge, bond order, density of states, energy levels
and contour maps of electron density. By this method, the transformation into
paraelectric material by ferroelectric material was discussed with respect to
relative permittivity as measured experimentally. Furthermore, X-ray
photoelectron spectroscopy (XPS) at the valence energy level was used on the
Sr-substituted cluster, and the experimental spectrum was compared to the
calculated one to evaluate the appropriateness of the cluster model. The overlap
population between the A site in BaTiO3 and oxygen showed either a covalent or
ionic nature depending on the elements. In addition, the relative permittivity
related to the overlap population between site A and Ti resulting in lower
permittivity for the trivalent elements such as Y and Gd. The computer
simulation can be applied to design properties of the ceramics in the microwave
range.
An Analytical Symmetric Double-Gate Silicon-on-Insulator Metal-Oxide-Semiconductor Field-Effect-Transistor Model
Authors: Jang Sheng-Lyang , Man-Chun Hu Man-Chun Hu , Shau-Shen Liu Shau-Shen Liu
Published: October 2002

A new complete and analytical drain current model for symmetric double-gate silicon-on-insulator metal-oxide-semiconductor field-effect-transistors (SOI MOSFETs) is presented. The model applicable for digital/analog circuit simulation contains the following advanced features: precise description of the subthreshold, near threshold and above-threshold regions of operation by one single expression; considering the source/drain resistance; inclusion of important short channel effects such as velocity saturation, drain induced barrier lowering and channel length modulation; self-heating effect due to the low thermal conductivity of the buried oxide; impact-ionization of MOS devices and parasitic bipolar junction transistor associated with drain breakdown. It was developed using a quasi-two-dimensional Poisson equation.
Performance of a-Si:H Thin Film Transistors Fabricated by Very High Frequency Discharge Silane Plasma Chemical Vapor Deposition
Authors: Takechi Kazushige , Takagi Tomoko , Setsuo Kaneko Setsuo Kaneko
Published: October 2002

This paper discusses the dependence of a-Si:H thin film transistor (TFT) performance on the plasma excitation frequency for a-Si:H film deposition. We studied the effects of the plasma excitation frequency over the range of 13.56–50 MHz, altering the deposition rate under various conditions. At the conventional 13.56 MHz frequency, the field effect mobility value decreases to 0.19 cm2V-1s-1 at a deposition rate of 76nm/min. As the excitation frequency increases, the rate of mobility drop to the deposition rate decreases in the high rate deposition region. A mobility value as high as 0.40 cm2V-1s-1 can be obtained at a high deposition rate of 130 nm/min using a 50 MHz frequency.
16.0% Efficient Thin-Film CdS/CdTe Solar Cells
Authors: Aramoto Tetsuya , Kumazawa Seiji , Higuchi Hiroshi , Arita Takashi , Shibutani Satoshi , Nishio Tuyoshi , Nakajima Junji , Tsuji Miwa , Hanafusa Akira , Hibino Takeshi , Omura Kuniyoshi , Hideaki Ohyama Hideaki Ohyama , Mikio Murozono Mikio Murozono
Published: October 2002

High efficiency cadmium sulfide (CdS)/cadmium telluride (CdTe) solar cells have been developed using ultrathin CdS films having a thickness of 50 nm. CdS films deposited on indium tin oxide (ITO)/#1737 glass substrates by the metal organic chemical vapor deposition technique, and CdTe films subsequently deposited by the close-spaced sublimation technique were used for the fabrication of CdS/CdTe solar cells. A photovoltaic conversion efficiency of 16.0% under Air Mass (AM) 1.5 conditions has been measured by the Japan Quality Assurance Organization.
Photoluminescence of 3C-SiC Epilayers Grown on Lattice-Matched Substrates
Authors: Katsushi Nishino Katsushi Nishino , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

The photoluminescence (PL) spectra of 3C-SiC epilayers grown on 15R-SiC and on 3C-SiC were measured. The PL spectra show strong exciton-related peaks and weak impurity-related peaks. The epilayers are of high quality and have a low density of impurities. Peaks due to excitons bound to neutral nitrogen showed very little shift induced by strain. Peaks considered to be due to free exciton recombination were observed and analyzed. Defect-related bands, usually observed for 3C-SiC grown on Si, were not observed. Although weak defect-related peaks were still observed, the epilayers have a lower density of defects than those on Si.
Mössbauer Time Spectra of the Nuclear Forward Scattering from Coherently Vibrating Resonant Nuclei
Authors: Mitsui Takaya , Shimizu Tatsuo , Imai Yoshihiko , Yoda Yoshitaka , Zhang Xiao Wei , Takei Humihiko , Kikuta Taikan Harami
Published: October 2002

The time evolution of the nuclear forward scattering from an antiferromagnetic 57FeBO3 single crystal exposed to an RF magnetic field synchronized with synchrotron radiation was investigated. The resonant nuclei were coherently vibrated by the RF magnetic field in a crystal. In the measured time spectra, intensity enhancement appeared when the initial magnetization state of the crystal was restored. The measured time spectra were analyzed by applying the multiple nuclear resonant absorption theory to the system of vibrating nuclei.
Observation of Induction Power Dependence on the Magnetic Neutral Loop Discharge Plasma Thermalization Phenomena
Authors: Tsuboi Hideo , Toshio Hayashi Toshio Hayashi , Taijiro Uchida Taijiro Uchida
Published: October 2002

A few years ago, the concept of magnetic neutral line discharge plasma was presented, and a preliminary experiment demonstrated its usefulness in plasma processing. Subsequently, the electron behavior was analyzed theoretically, and the possibility of a high energy gain of electrons due to meandering motion in the magnetic neutral loop under a rf induction field along the loop was revealed. Recently, evidence has been found that the stronger the applied rf power is, the easier is the thermalization of electrons. Here, the results of studying this dependence are reported and the reason for the dependence is presented.
Computer Studies of Depth Profiles due to Carbon Fullerene Impacts on a TiD2 Target
Authors: Tetsuya Muramoto Tetsuya Muramoto , Yasunori Yamamura Yasunori Yamamura
Published: October 2002

We studied the depth profile due to carbon fullerene impacts on a TiD2 target, using the time-evolution Monte Carlo code DYACAT. Simulations have been performed for incident energies per atom of 100 eV–5 keV, and for the clusters (C)

N

(N=30–240) and a monatomic ion. In the case of the lower energy cluster bombardment, the projected range of carbon fullerenes is larger than that of monatomic ions, because the cluster atoms in the lower part of the cluster clear the way for the subsequent cluster atoms. In the higher cluster energy region, the projected range is smaller than that of monatomic ions, because the initial velocity of the cluster atoms is randomized due to collisions of a cluster atom with a cluster atom or a moving target atom. The cluster effect of the projected range is determined by the competition process of the clearing-the-way effect and the cluster-enhanced randomization effect.
New Contactless Inductive Sensor for the Measurement of Concentration of an Electrolytic Solution
Authors: Abu Bakar Md. Ismail Abu Bakar Md. Ismail , Katsunori Shida Katsunori Shida
Published: October 2002

In this paper an inductive sensor with a new and simple contactless structure to determine the concentration of an electrolytic solution is presented. The authors propose a novel idea of designing the sensing coil of the sensor so that the magnetic field is focused inside the conducting liquid, thereby increasing the sensitivity of the sensing coil. By detecting the change in inductance of the sensing coil due to a solution of known concentrations of a particular electrolyte, a database is created. With the help of this database it is possible to estimate the unknown concentration of an electrolytic solution. It was tested for various concentrations of NaCl and it shows a distinct response for each concentration.
A New Technique for Via Plugging through the Selective Chemical Vapor Deposition of Aluminum
Authors: Kim Byung-Yoon , Dong-Chan Kim Dong-Chan Kim , Seung-Ki Joo Seung-Ki Joo
Published: October 2002

A new technique for selective via plugging in order to obtain perfectly planarized multilevel metallization is demonstrated through the chemical vapor deposition (CVD) of aluminum. It has been found that the selectivity between aluminum and silicon oxide can be enhanced by sputter-deposition of ultrathin layers of palladium and cobalt on aluminum interconnection lines prior to patterning of via holes. It was found that the coating of aluminum oxide with these noble metals was mainly responsible for the selectivity enhancement. This new technique was demonstrated to be highly suitable for actual device fabrication.
Crystal Growth and Optical Properties of CuAl(SxSe 1-x) 2 Alloys
Authors: Sho Shirakata Sho Shirakata , Shigefusa Chichibu Shigefusa Chichibu , Shigehiro Isomura Shigehiro Isomura
Published: October 2002

Single crystals of CuAl(SxSe1-x
)2 alloys have been successfully grown by the chemical vapor transport method. Photoreflectance (PR) and photoluminescence (PL) measurements have been carried out at 77 K. From PR measurements, exciton energies (in eV) at 77 K have been obtained as a function of alloy composition x: E
A =3.546 x + 2.736 (1-x) - 0.35x(1-x), E
B=3.709x + 2.849 (1-x) - 0.39x(1-x), E
C=3.692x + 3.012 (1-x) - 0.33x(1-x). PL spectra are dominated by a broad emission band centered at 2.0 eV, although weak exciton and edge emission (2.9 eV) peaks have been observed for 0.84 ≤x ≤0.96 and 0.68 ≤x ≤0.96, respectively.
Combination of Additional Noncontact Dampers and Superconducting Levitation Using Melt-processed YBaCuO Bulk Superconductors
Authors: Hidekazu Teshima Hidekazu Teshima
Published: October 2002

Damping properties in superconducting levitation have been investigated using melt-processed YBaCuO bulk superconductors. The damping of superconducting levitation is so small that additional noncontact dampers are required for practical use of superconducting levitation. Eddy current dampers and superconducting dampers of sintered YBaCuO materials have been proposed and studied as additional noncontact dampers. The damping coefficient has been improved about 20-fold by combining a copper damper with superconducting levitation, and further enhancement can be expected.
Acoustic Emission in Lead Lanthanum Zirconate Titanate PLZT (18/40/60) Ceramics with Small Electrostriction
Authors: Aburatani Hideaki , John P. Witham John P. Witham , Kenji Uchino Kenji Uchino
Published: October 2002

Electric field induced acoustic emission (AE) was studied in electrostrictive lead lanthanum zirconate titanate (PLZT) (18/40/60) ceramics, which has a field induced strain of 0.02% at an electric field of 20 kV/cm. A field induced AE was constantly observed for an applied field greater than 10 kV/cm. Furthermore, the AE was present even when the applied field was being decreased. The critical electric field above which AE was generated was determined. The total AE event count simply increased with time under constant electric fields, and the AE event rate increased with increasing the applied electric field.
Field Dependence of Magnetoresistance in Granular Ag–Co Thin Films
Authors: Ryoichi Ohigashi Ryoichi Ohigashi , Eiji Kita Eiji Kita , Myron B. Salamon Myron B. Salamon , Akira Tasaki Akira Tasaki
Published: October 2002

The proportionality of the giant magnetoresistance (MR) to <cos
θ>2, where θ is the angle between the local magnetization and the applied field, was tested in granular Ag–Co (20 at.%) thin films. The assumption that <cos
θ>2=(M/M
s)2 does not give a linear relation. To deduce the granule size distribution, magnetization data for the superparamagnetic state were fitted using a set of Langevin functions on a granule size histogram. Assuming that the scattering rate is proportional to the surface area of each granule in such a system and that the granules are spherical, we weight the average of cos
θ in the size distribution by the surface area. If granules containing more than 900 Co atoms are ignored when determining the average value of cos
θ, the MR varies linearly with this quantity, which is denoted as <cos
θ> sur.av.
2. We suggest that the surface roughness enhances the contribution of smaller granules to the MR.
Deposition Characteristics of (Ba, Sr)TiO3 Thin Films by Liquid Source Metal-Organic Chemical Vapor Deposition at Low Substrate Temperatures
Authors: Kang Chang Seok , Cho Hag-Ju , Hwang Cheol Seong , Lee Byoung Taek , Lee Ki-Hun , Horii Hideki , Kim Wan Don , Sang In Lee Sang In Lee , Moon Yong Lee Moon Yong Lee
Published: October 2002

The deposition characteristics of (Ba, Sr)TiO3 (BST) thin films using a liquid source metal-organic chemical vapor deposition on a 6-inch-diameter Pt/SiO2/Si wafer were investigated. Ba(DPM)2 tetraglyme, Sr(DPM)2 tetraglyme and Ti(DPM)2(O-i-Pr)2, dissolved in n-butyl acetate, were used as the sources of Ba, Sr and Ti, respectively. Step coverage, within-wafer uniformities in composition and thickness of the BST films were investigated as a function of substrate temperatures ranging from 420° C to 570° C. As the substrate temperature decreased, the step coverage improved, whereas the within-wafer uniformities degraded. From BST films deposited in a temperature range from 450° C to 480° C, good step coverage (>80%), as well as good within-wafer uniformity were obtained. However, in that temperature range, hazy deposition was observed due to many humps on the surface. The humps are an agglomeration of crystalline grains and are a few hundred Å in diameter, which have a Ti-rich composition compared to flat film region.
A New Pulsed Laser Deposition Method Using an Aperture Plate
Authors: Inoue Narumi , Ozaki Tatsuya , Monnaka Toshiaki , Fujimoto Shigeru Kashiwabara
Published: October 2002

A new off-axis pulsed laser deposition method using an aperture plate is proposed for the purpose of depositing high surface-quality Ta2O5 thin films without large fragments and/or droplets. The angular distribution of droplets and growth species emitted from the target is examined. Then, the oxygen pressure and laser energy dependencies of the number of droplets and the film thickness are also examined. The results indicate that the aperture plate plays an important role of limiting the path of the traveling droplets and of capturing the droplets traveling toward the off-axis substrate. On the other hand, the film deposition rate is not slow even when using the plate because the species pass through the aperture hole and reach the substrate by scattering. Using a 5 mm aperture plate, a good surface quality Ta2O5 film is obtained under the optimum condition of 200–300 mTorr oxygen pressure.
Formation of a Positive Photoresist Thin Film by Spin Coating: Influence of Atmospheric Humidity
Authors: Yada Toshio , Maejima Taro , Aoki Masaru
Published: October 2002

Experimental film formation of a positive photoresist by spin coating at various atmospheric humidities was investigated. The temperature of the photoresist solution outside of the wafer increases during the intermediate stages of the spinning process in proportion to the humidity and decreases during the later stages. The baked films formed at higher humidities are thinner than those formed at lower humidities during the first stage of the spinning process due to the initial high outflow rate, but thick films are formed during the later stages of the spinning process due to the low outflow rate. The minimum thickness deviation, which is in the intermediate stage of the spinning process, increases at a high humidity with increased distinction at lower spin speeds.
Enhancement of the 15.4 nm Line of the Lithiumlike Aluminum Recombining Plasma Laser using a Half Cavity
Authors: Kawachi Tetsuya , Ando Kozo , Oyama Hitoshi , Hara Tamio , Yoshinobu Aoyagi Yoshinobu Aoyagi
Published: October 2002

A 30-mm long aluminum slab target was irradiated by a line-focused Nd; glass laser light. The relative intensity of the 3d
2
D–4f
2
F laser line (15.4 nm) of the lithiumlike aluminum ions was measured. In this experiment, we put a Mo/Si multilayer mirror on the opposite side of the spectrometer to construct a half cavity. With the use of this mirror, the intensity of the 15.4 nm line became 1.8 times larger than the case without the mirror.
Effect of Oxide Precipitate Sizes on the Mechanical Strength of Czochralski Silicon Wafers
Authors: Sueoka Koji , Akatsuka Masanori , Adachi Hisashi Katahama
Published: October 2002

The effect of oxide precipitate sizes on the mechanical strength of Czochralski silicon (CZ-Si) wafers has been studied with emphasis on the mechanism of slip dislocation generation by oxide precipitates. Thermal stresses, which are larger than those set up in wafers during actual device processes, were applied to two-step annealed wafers. It was determined by X-ray topography and transmission electron microscopy observations that both platelet and polyhedral precipitates can generate slip dislocations when their size is larger than approximately 200 nm. With further experiments, it is concluded that the precipitates cannot generate slip dislocations during actual device processing when the precipitate size is smaller than 200 nm, and this conclusion is independent of the precipitate density. The stress concentration of compressive thermal stresses applied to oxide precipitates should be the cause of slip dislocation generation. Three critical stress curves of slip dislocation generation were obtained for the wafers, in which the platelet sizes are approximately 70 nm, 200 nm and from 330 nm to 490 nm.
Study of GaAs(001) Surfaces Treated in Aqueous HCl Solutions
Authors: Shinya Osakabe Shinya Osakabe , Sadao Adachi Sadao Adachi
Published: October 2002

Chemically treated GaAs(001) surfaces in aqueous HCl (0.36≤x≤36 wt%) solutions at 20° C have been studied using spectroellipsometry (SE), ex situ atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact-angle measurement techniques. The SE data clearly indicate that the solutions cause the removal of the native oxide film. When the native oxide film is etch-removed, the resulting surface is still rough (∼8 Å). Longer exposure to the solutions with x≤12 wt% results in surface roughening; the thickness of the roughened layer immersed in the solution with x=3.6 wt% for t=100 min, for example, is ∼60 Å, about twice as large as the AFM rms value (∼27 Å); the difference is due to the SE technique being sensitive to both the surface microroughness and the adsorbed chemical species. By contrast, the concentrated HCl (36 wt%) etching provides a nearly flat (AFM rms of ∼7 Å), Cl-terminated surface even after considerable etching. The XPS spectra clearly indicate the presence of chlorine on the HCl-treated surfaces. The HCl-cleaned GaAs surfaces are also found to be highly hydrophobic.
Enhancement/Depletion Surface Channel Field Effect Transistors of Diamond and Their Logic Circuits
Authors: Akira Hokazono Akira Hokazono , Hiroshi Kawarada Hiroshi Kawarada
Published: October 2002

Using the p-type surface-conductive layer of diamond film, enhancement mode and depletion mode metal-semiconductor field effect transistors were fabricated on the same surface by changing the metals of the gate electrode. The threshold voltages of p-type metal semiconductor field effect transistors (MESFETs) can be controlled from negative (enhancement mode) to positive (depletion mode) as the electronegativities of gate metals increase. By the realization of high transconductance and the fabrication of enhancement and depletion mode MESFETs, the E/D-type logic circuits such as inverter, NAND and NOR circuits were fabricated for the first time.
Si Molecular Beam Epitaxial Growth over an Atomic-Layer Boron Adsorbed Si(001) Substrate and Its Electrical Properties
Authors: Takashi Suemasu Takashi Suemasu , Masaki Yamamoto Masaki Yamamoto , Ken'ichiro Takakura Ken'ichiro Takakura , Satoshi Hashimoto Satoshi Hashimoto , Yoshinao Kumagai Yoshinao Kumagai , Fumio Hasegawa Fumio Hasegawa
Published: October 2002

Si/boron(B)/Si(001) atomic-layer doping (ALD) structures were grown on Si(001) substrates by molecular beam epitaxy (MBE), and the electrical properties and crystal quality were evaluated. Preadsorption of B on Si(001) during HBO2 irradiation was controlled in situ by reflection high-energy-electron diffraction (RHEED). Hall measurements revealed that the hole concentration of the Si overlayer saturated at the B coverage of 1 monolayer (ML), although the B adsorption did not appear to saturate because the roughness of the Si overlayer increased monotonously with HBO2 irradiation time. Observation with cross-sectional transmission electron microscopy (XTEM) indicated that the adsorbed B atoms formed clusters and/or precipitates for the B coverages beyond 1 ML, and hence the hole concentration saturated at the B coverage of 1 ML.
Characterization of Interface Layer of Silicon on Sapphire Using Spectroscopic Ellipsometry
Authors: Jayatissa Ahalapitiya Hewage , Yamaguchi Tomuo , Sawada Kazuaki , Aoyama Mitsuru , Sato Fumio
Published: October 2002

Epitaxial silicon on sapphire (SOS) grown using a commercial process was characterized by means of spectroscopic ellipsometry (SE). The SE data of a thin Si layer of SOS were analyzed based on the air/SiO2/Si/Al2O3 structure, in which the Si layer was analyzed using the established optical properties of bulk-Si and model dielectric functions (MDFs) of Si, and also with two layers, the bottom layer with MDFs and the top layer with bulk-Si. The best fit of the SE data with two layers shows that the optical properties of the Si layer in the early stage of growth are different from those of bulk-Si due to the effect of lattice mismatch between Al2O3 and Si. The thickness of the interface layer estimated from SE data analysis is around 20 nm, in reasonable agreement with the previous reports.
Hysteretic Current–Voltage Characteristics for a-Axis Oriented Grain in Y1Ba2Cu3O7-δFilms
Authors: Yoshihiro Ishimaru Yoshihiro Ishimaru , Youichi Enomoto Youichi Enomoto
Published: October 2002

We observed a hysteretic current–voltage (I–V) characteristic on lateral type intrinsic Josephson junction using Y1Ba2Cu3O7-δfilms. Ana-axis oriented needle-like grain surrounded byc-axis oriented grains is used for the junctions. The junctions using as-grown films show resistively shunted junction (RSJ) typeI–Vcharacteristics. After appropriate annealing in pure Ar-gas, this junction property changes to hystereticI–Vcharacteristics with several voltage jumps from no hysteresis. It is explained that conductivity of the CuO chain decreases by the annealing.