bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Migration of Cd in Amorphous Cd–Sb Films
Authors: Yasube Kashiwaba Yasube Kashiwaba , Hideshi Abe Hideshi Abe , Toshio Ikeda Toshio Ikeda , Hiroshi Horie Hiroshi Horie , Mitsuru Nakamura Mitsuru Nakamura , Yoshiyuki Shoubuzawa Yoshiyuki Shoubuzawa
Published: October 2002

The local structural and compositional changes in amorphous Cd–Sb (25–30 wt% Cd) films, which are related to the memory switching of the film, were observed under current flow through a fine Ag filament deposited on the film. First the Joule heat generated at the Ag filament induced the phase transition from the amorphous state to the polycrystalline state, resulting in the formation of a conducting channel. In this process, selective thermal diffusion of Cd and its accumulation at the boundary of the channel were observed. Further flow of current generated a feather-like pattern at the boundary and then induced the phase transition in the outer region, resulting in the formation of a second channel.
The Growth and Characterization of Silicon/Silicon Carbide Heteroepitaxial Films on Silicon Substrates by Rapid Thermal Chemical Vapor Deposition
Authors: Wu Kuen-Hsien , Fang Yean-Kuen , Jen-Yeu Fang Jen-Yeu Fang , Jun-Dar Hwang Jun-Dar Hwang
Published: October 2002

SiC and Si heteroepitaxial films were sequentially deposited on Si substrates to form Si/SiC/Si multilayer structures using a refined rapid thermal chemical vapor deposition (RTCVD) technology. Refined RTCVD is a combination of a graded composition process with rapid thermal chemical vapor deposition. The optimum growth conditions and characteristics of the as-grown films in the Si/SiC/Si multilayers were studied by structrual (X-ray, TEM) and electrical (four-point probe , Hall measurement) methods. N-Si/n-SiC/p-Si double-heterojunction diodes (DHD) were fabricated to determine the suitability of the multilayer films for device applications. Analysis of the I–V characteristics of the diode indicates that fine control of the thickness of the graded layers without degrading the crystallinity of the films results in high-quality heteroepitaxial SiC and Si films which are suitable for multilayer device applications.
Electroluminescent Diodes Utilizing Polysilanes
Authors: Akihiko Fujii Akihiko Fujii , Kenji Yoshimoto Kenji Yoshimoto , Masayoshi Yoshida Masayoshi Yoshida , Yutaka Ohmori Yutaka Ohmori , Katsumi Yoshino Katsumi Yoshino , Hideki Ueno Hideki Ueno , Masaya Kakimoto Masaya Kakimoto , Hiroyuki Kojima Hiroyuki Kojima
Published: October 2002

Electroluminescent (EL) diodes utilizing polysilanes have been fabricated, and their optical and electroluminescent characteristics have been investigated. We have succeeded in demonstrating electroluminescence from the ultraviolet region to the visible region using the EL diodes with thin polysilane films. The diode characteristics are discussed taking the polymer structure into consideration.
Development of Two-Axis Actuator with Small Tilt Angles for One-Piece Optical Heads
Authors: Makoto Nagasato Makoto Nagasato , Isao Hoshino Isao Hoshino
Published: October 2002

An integrated one-piece optical head for optical disk drives is effective for reducing the head size and tracking error signal offset. The authors have developed a two-axis actuator which can drive a one-piece optical head with small tilt angles by compensating the torque which has two main components acting in opposite directions; one originates from the focusing driving coil and the other from the tracking coil. The tilt angle of ±0.8 mrad was achieved when the extent of actuator movement was ±0.5 mm in the focusing direction and ±0.4 mm in the tracking direction.
Observation of Electroluminescence from CdSe-Microcrystal-Embedded Indium Tin Oxide Film
Authors: Matsuoka Jun , Kawasaki Yasushi , Hiroyuki Nasu Hiroyuki Nasu , Kanichi Kamiya Kanichi Kamiya
Published: October 2002

CdSe-microcrystal-embedded indium tin oxide thin film was prepared by the rf-sputtering method. The absorption edge of the film was at 690 nm. This film exhibited red electroluminescence when a voltage of 6 V/cm was applied. The wavelength of the emission peak was longer than 820 nm.
Structure and Properties of CeO2–Al2O3–SiO2 Glasses
Authors: Lin Sin-Lung , Lee Chii-Shyang Hwang
Published: October 2002

The density, molar volume, refractive index, molar refractivity, and infrared and XANES spectra of CeO2–Al2O3 –SiO2 glasses prepared at 1600° C for 3 h in N2 have been investigated. The IR reflection data are treated by Kramers-Kronig transformation. Results of IR spectra show that ceria is the network modifier and favors the formation of the [ SiO4] tetrahedron with nonbridging oxygen. The XANES data of the cerium LIII edge show that the majority of cerium ions in cerium aluminosilicate glasses are the Ce3+ ions. The density and refractive index of the glass increase with increasing alumina or ceria content.
Simulations of the Effects of Tip Apex Geometries on Atomic Force Microscopy Images
Authors: Masaharu Komiyama Masaharu Komiyama , Katsuyuki Tazawa Katsuyuki Tazawa , Kazuya Tsujimichi Kazuya Tsujimichi , Akiyasu Hirotani Akiyasu Hirotani , Momoji Kubo Momoji Kubo , Akira Miyamoto Akira Miyamoto
Published: October 2002

Simulation works on the effects of tip apex geometries on atomic force microscopy (AFM) images were examined. Tips and samples employed in those simulations were mostly made of a single component. Short-range interatomic potentials such as Lennard-Jones and Morse were used. With these potentials, it was found that a single atom tip (a tip with an atom protruding at its apex) is necessary for obtaining true atomic resolution. In many cases flat tip geometries (tips with multiple atoms at their apexes) produce various images that do not correspond to the surface atom arrangements, which may lead to various faulty AFM image interpretations.
Surface Modification of Fluorocarbon Polymers by Vacuum-UV Excimer Lamp Irradiation in Reactive Gas Atmosphere
Authors: Johannes Heitz Johannes Heitz , Hiroyuki Niino Hiroyuki Niino , Akira Yabe Akira Yabe
Published: October 2002

Irradiation of poly(tetrafluoroethylene) (PTFE) and poly(tetrafluoroethylene- co-hexafluoropropylene) (FEP) polymer films in an ammonia or hydrazine atmosphere with vacuum UV light resulted in a hydrophilic surface, where abstraction of fluorine atoms and introduction of nitrogen, oxygen, and hydrogen atoms occurred. We used Kr2
* and Xe2
* excimer lamps at wavelengths of 172 nm and 146 nm, respectively. The reaction mechanism for chemical surface modification is discussed on the basis of the results of X-ray photoelectron spectroscopy, secondary ion mass spectrometry, scanning electron spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy analyses.
Sum-peak Method and Angular Correlation Correction for a 60Co Source by a Ge(Tl) Detector
Authors: Asano Yuzo , Mori Shigeki , Yoshinori Ohta Yoshinori Ohta , Yuichi Tsujita Yuichi Tsujita
Published: October 2002

The sum-peak method was applied for a measurement of radioactivity of a 60 Co source by an 80 cm3 Ge(Tl) detector. A correction factor for the angular correlation effect between two cascade γ-rays from the 60 Co source was determined to be about 9% in the present experimental setup by a Monte Carlo simulation.
Basic Characteristics of Beam Position Drift and Field Stitching Error Caused by Electron Beam Column Charging
Authors: Morita Hirofumi , Junichi Kato Junichi Kato , Nobuo Shimazu Nobuo Shimazu
Published: October 2002

The beam drift caused by column charging and its influence on field stitching error were experimentally studied in an electron optical column with a contaminated inner surface. The raw drift characteristics indicate that secondary electrons with an energy lower than that of an electron accelerated by a voltage equal to the deflection voltage move from the substrate to the electrode surface and are the main cause of charging. Pattern writing was performed to examine field stitching error. For a continuously moving stage, the errors are roughly as large as the drift and their direction and magnitude change dramatically between neighboring rows of fields. The results on stitching error can be explained very well by considering the details of the writing procedure and the drift characteristics.
Electromagnetic Backscattering from Two Cascade Opposite Rotating-Fan Array with Tilted Plate Metal Blades
Authors: Bor Sheau-Shong , Yang Shui-Yuan , Yeh Shu-Ming
Published: October 2002

The scattering problem of electromagnetic waves from a two cascade opposite rotating-fan array with tilted plate metal blades is addressed in this work using the physical optics and physical theory of diffraction equivalent-current techniques with the quasi-stationary method. Experimental results indicated that, in the far zone, the field can be considered harmonic, and expressions for the spectral components of the field are obtained. The spectrum characteristics are of a form similar to a frequency-modulated tone. Experimental results confirm the validity of the theoretical work.
A Theoretical Study on the Gas Sensitive Characteristics of Semiconductive Ceramic Sensors
Authors: Fengqi Bao , Niu Mengnian Niu Mengnian , Zhao Xianwu Zhao Xianwu
Published: October 2002

When adsorbed oxygen ions react with introduced reducing gas molecules, the fraction of densities of reacted oxygens and originally adsorbed oxygens was assumed to correspond to the fraction of surface occupied by introduced gas molecules used in the Langmuir equation. According to Boltzmann statistics and Langmuir equation, we obtain an analytic expression of sensitivity of sensor as a function of concentration of reducing gas, heating temperature and material parameters. The theoretical results are in good agreement with the experimental data which has been reported on ZnO and SnO2 sensor.
Rapid Thermal Annealing Effects in CdTe (111) Thin Films Grown on GaAs (100) Substrates
Authors: Kim M. D. , Kang T. W. , Han M. S. , Kim T. W.
Published: October 2002

Photoluminescence (PL) and double crystal X-ray rocking curve (DCRC) measurements have been carried out to investigate the rapid thermal annealing (RTA) effects in CdTe (111) epilayers grown on GaAs (100) by molecular beam epitaxy. The result of the X-ray diffraction showed that the orientation of the grown CdTe films was the (111) orientation. The full width at half maximum (FWHM) of the DCRC for as-grown CdTe layer was 400 arcs. When RTA was performed at 550° C, the FWHM of the DCRC for the CdTe layer decreased 265 arcs. The results of the PL spectra showed that the luminescence intensity of a bound exciton ( D0, X) for the CdTe/GaAs annealed at 550° C was raised by as much as about 53 times in comparison to the as-grown CdTe. The relative intensity ratio between ( D0, X) and the luminescence related to the defects for the as-grown and the annealed CdTe decreased by a factor of 7.8. These results indicate that the crystallinity of the CdTe epilayers grown on GaAs (100) is improved by RTA and that the RTA CdTe films grown on Si can be used for applications as buffer layers for the growth of Hg

x

Cd1-
x

Te.
Self-Organized Dot/Columnar Structures and Quasi-Perfect CuPt-Type Ordering in (GaP)n(InP)n Superlattices Grown on GaAs (N11) Substrates by Gas Source Molecular Beam Epitaxy
Authors: Kim Seong-Jin , Asahi Hajime , Takemoto Minori , Asami Kumiko , Misaichi Takeuchi Misaichi Takeuchi , Shun-ichi Gonda Shun-ichi Gonda
Published: October 2002

(GaP)

n

(InP)

n

short-period superlattices (SLs) are grown on GaAs (N11) and (100) substrates by gas source molecular beam epitaxy. Transmission electron microscopy observations show that the SLs grown on GaAs (311)A and (411)A have lateral-composition-modulated dot/columnar structures with a lateral period of about 10–20 nm, while on GaAs (100), wire structures are formed. Photoluminescence (PL) peak energies are greatly dependent on substrate orientation and monolayer number n corresponding to the lateral composition modulation. On the other hand, the (GaP)

n

(InP)

n

SLs grown on GaAs (111) have no lateral composition modulation for n≤4 and have quasi-perfect CuPt-type ordering along the <111> growth direction for n=1, where the PL peak energy is 321 meV lower than that of disordered InGaP alloy. Quantum dots formed in (GaP)2(InP)2.5 SL/ In0.49Ga0.51P multilayers by self-organization exhibit strong 77 K PL with a full width at half-maximum of about 70 meV. Anomalous temperature variation of PL peak energy is observed in these self-organized structures.
Sampled Servo Read Only Memory System Using Single Carrier Independent Pit Edge Recording
Authors: de Kock Joost P. , Kobayashi Seiji , Ishimoto Tsutomu , Hisayuki Yamatsu Hisayuki Yamatsu , Hiroshi Ooki Hiroshi Ooki
Published: October 2002

Single carrier independent pit edge recording (SCIPER) is a high-density optical disk recording method which stores information by modulating the position of pit edges in small discrete steps. A high-density read only memory (ROM) system for computer use is one possible application of SCIPER technology. This application requires fast access times and high recording densities, and hence we are developing a SCIPER system based on a red 680 nm laser and sampled servo techniques. We chose a SCIPER format with a linear recording density of 0.24 µm/bit and a track pitch of 1.0 µm. With this format and under optimal conditions we obtained tangential and radial skew margins of ±0.75° and ±0.7°, respectively, and found that the system can tolerate clock jitter values of up to 3.4 ns rms. By employing zone constant angular velocity (CAV) we expect to realize a 3.5-inch, 1.3-Gbyte ROM drive.
Rectification of Millimeter Waves in Nanometer-Scale Si-Inversion-Layer Metal-Oxide-Semiconductor Field-Effect Transistors
Authors: Tomaru Tatsuya , Matsuoka Tsuneo Ichiguchi
Published: October 2002

We measured the millimeter wave response of nanometer-scale Si metal-oxide-semiconductor field-effect transistors (Si-MOSFETs) between 1.8 K and 4.2 K, which showed irregular conductance oscillation versus gate voltage and nonlinear I–V characteristics, which we attributed to hopping conduction between localized states. Sign-changeable rectified current of 75 GHz millimeter waves was observed, and the peak positions in plots of rectified current versus gate voltage coincided with those of conductance oscillation. The rectification occurred even when electrons were heated considerably by millimeter waves. The rectification was also explained in terms of a hopping regime.
GaSb-Growth Study by Realtime Crystal-Growth Analysis System Using Synchrotron Radiation Photoelectron Spectroscopy
Authors: Maeda Fumihiko , Watanabe Yoshio , Yasuji Muramatsu Yasuji Muramatsu , Masaharu Oshima Masaharu Oshima
Published: October 2002

A system has been developed for realtime crystal-growth analysis by photoelectron spectroscopy, using vacuum ultraviolet (VUV) light from synchrotron radiation. This system consists of a VUV synchrotron radiation beamline and growth/analysis apparatus in which photoelectron spectroscopy is performed. A “non-scanning” photoelectron spectroscopy measurement method that uses only electron energy dispersion on a multi-channel detector achieves sub-second resolution. This system was used to monitor the GaSb-growth process by alternately supplying Ga and Sb molecular beams; the changes in the chemical state were analyzed with sub-second resolution. The Ga supply resulted in a Ga-full surface; Ga droplets formed on this surface, in which the Sb atoms remained lying on the Ga layer. The Sb supply did not change the ratio of Ga and Sb atoms at the surface from the initial value. These results show that, exposure to an Sb flux causes a crystal surface to once again become an Sb-rich surface although Ga droplets were previously formed during exposure to a Ga flux a GaSb surface was thus successfully grown.
Effects of UV Exposure on E' Centers Formed in Crushed Quartz Grains
Authors: Makoto Hirai Makoto Hirai , Motoji Ikeya Motoji Ikeya
Published: October 2002

Electron spin resonance (ESR) study of E' centers in crushed quartz (SiO2) indicated the formation of a new type of E' center by UV-irradiation. On the other hand, the concentration of E' centers formed by γ-irradiation in the crushed quartz is reduced by UV-irradiation. It was possible to distinguish between the three types of E' centers in crushed quartz (E' c: formed simply by crushing, E' UV: formed by crushing and UV-irradiation and E'γ: formed by crushing and γ-irradiation) using UV-irradiation. The distribution of the activation energy of the E' centers just after crushing was revealed by annealing experiments and computer simulation. The technique of characterization by UV-irradiation will be useful for evaluating the local strain in SiO2, especially in natural quartz.
Field Emission Microscope Observations of H2- and Metal-Phthalocyanines
Authors: Hiroshi Morikawa Hiroshi Morikawa , Ken-ichi Okamoto Ken-ichi Okamoto
Published: October 2002

Field emission microscope (FEM) observations were carried out on H2-, Fe-, Co-, Ni- and Cu-phthalocyanines vapor-deposited onto a tungsten tip. The various molecular image stabilities were quantitatively determined and compared among these phthalocyanines. About 30% of the four- and two-leaf patterns disappear immediately after they appear, irrespective of the kind of central atom in the phthalocyanine. Some of the remaining patterns gradually disappear according to the first-order reaction rate law, and the ones left have considerable stability. The probability of the patterns being stable increases with the increase in the number of d-electrons of the metal atom in the phthalocyanine. The once-stabilized four-leaf patterns also disappear upon raising or lowering of the tip voltage or raising of the tip temperature. Some of these behaviors differ depending on the kind of phthalocyanine while others do not.
Dipolar Association in Binary System: MIBK in Carboxylic Acids
Authors: Das J. K. , Dash S. K. , Swain S. Acharya
Published: October 2002

The dielectric constant (ε) of the binary mixtures of MIBK with some carboxylic acids viz. acetic acid, propanoic acid and butyric acid is measured at 303.16 K at 455 kHz. The experimental data are used to compute the excess dielectric constant (Δε), mutual correlation factor (g
ab), excess molar polarization (ΔP) and excess free energy of mixing (ΔG
ab) in these mixtures.
Generation and Detection of Wide-Frequency-Range Acoustic Phonons by Impulsive Stimulated Brillouin Scattering
Authors: Tomoyuki Hikita Tomoyuki Hikita , Naomi Oka Naomi Oka
Published: October 2002

The impulsive stimulated Brillouin scattering was applied over a wide frequency range. Using the light pulse of a non-mode-locked Q-switched YAG laser for probing, we could observe acoustic phonons with frequency as high as 5.41 GHz and as low as 46.1 MHz. Instead of scanning an optical delay line, the non-mode-locked Q-switched pulse was electronically scanned in the time domain. This gave the system an effective rectangular pulse, allowing the pulse to be adjusted to a desired length and at the same time, enabling minimum heating of the sample. The the diffracted light was detected using an avalanche photodiode together with a digital oscilloscope in the low-frequency region and using a streak optical oscilloscope in the high-frequency region.
Profile Distortion Caused by Local Electric Field in Polysilicon Etching
Authors: Ogino Satoshi , Fujiwara Nobuo , Miyatake Hiroshi , Harada Masahiro Yoneda
Published: October 2002

The relationships between the local side etch in polysilicon etching and the connection between polysilicon and silicon substrate were investigated. It was found that the local side etch occurs only when the polysilicon and the silicon substrate are connected. Also, when the polysilicon and silicon substrate were connected, the depth of the local side etch was found to be related to the size of the area of the silicon substrate exposed to the plasma because of the fact that the depth increases as the area of exposure of the silicon substrate increases. It appears that electrons are supplied from the plasma to the polysilicon through the connection between the polysilicon and the silicon substrate when the exposed area of the silicon substrate is large, and this electron supply is considered to enhance the local electric field which causes the local pattern distortion.
Ground Electric Field Effects on Rats and Sparrows: Seismic Anomalous Animal Behaviors (SAABs)
Authors: Ikeya Motoji , Furuta Hiroshi , Kajiwara Naemi , Anzai Hiroko
Published: October 2002

Electric field effects on behaviors of albino rats, Mongolian gerbils (sand rats), hair-footed Djungarian hamsters, guinea pigs and red sparrows (Avadavat) have been investigated in order to determine whether seismic anomalous animal behaviors (SAABs) witnessed prior to a major earthquake are due to seismic electric signals (SES). Animals placed on a wet conductive floor initially showed grooming, nervous and field avoidance behaviors and finally ran and jumped in panic as the ground field intensity was increased from 1 to 1000 V/m. An electromagnetic model of a fault, in which piezo-compensating bound charges appear as a result of sudden reduction of the piezoelectric polarization due to the release of seismic stress, gives sufficient field intensity to produce a critical body current of a few µA. It is considered that animals showed electrophysiological responses to seismic current.
Linear and Nonlinear Optical Properties of CdS and CdSe Nanoparticles Stabilized with Poly(N-vinyl-2-pyrrolidone)
Authors: Yao Hiroshi , Takahara Shigeru , Mizuma Hirokazu , Takashi Kozeki Takashi Kozeki , Toyoharu Hayashi Toyoharu Hayashi
Published: October 2002

CdS and CdSe nanoparticles were prepared in organic solvents in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). PVP plays an essential role in preventing the flocculation of concentrated nanoparticles (stabilizing effect), and in controlling the particle size under the influence of the solvent used. FT-IR measurements were performed to study the effect of the functional groups of PVP on particle size control at molecular levels. The PVP-coated CdS and CdSe nanoparticles obtained were dispersed in acrylonitrile-styrene (AS) copolymer or poly(2-hydroxyethyl methacrylate) (PHEMA) organic films, and third-order nonlinear optical susceptibilities |χ(3)| of these films were measured using a degenerate four-wave mixing (DFWM) technique. The largest |χ(3)| value of 1.1×10-7 esu was obtained by excitonic resonant excitation for about 4.0 vol% CdS-doped PHEMA film.
Femtosecond Dynamics of Nonresonant Third-Order Optical Nonlinearity of 1-(3-thienyl)-3-(4-chlorophenyl)propene-1-one Crystal and Solution
Authors: Takeshi Saito Takeshi Saito , Yoshihisa Yamaoka Yoshihisa Yamaoka , Yasuhiro Kimura Yasuhiro Kimura , Ryuji Morita Ryuji Morita , Mikio Yamashita Mikio Yamashita
Published: October 2002

For the crystal and solution of 1-(3-thienyl)-3-(4-chlorophenyl)propene-1-one (TCPP), which is transparent over the whole visible region, the nonresonant third-order nonlinear dynamics is investigated by time-resolved degenerate four-wave mixing spectroscopy. The temporal nonlinear behaviors of both crystal and solution exhibit the instantaneous responses during 80 fs excitation at around 625 nm. The third-order nonlinear susceptibilities are determined to be |χ(3)

b
b
b
b
| = 7.1 ×10-13 esu for crystal and |χ (3)TC
1111| = 7.1 ×10-14 esu at 1 mol/l for solution. This suggests that the TCPP crystal has a large value of χ(3)/ατ= 2.4 ×103 esu·cm·s-1 under the assumption of the nonlinear response time τ= 30 fs (absorption coefficient α= 0.01 cm-1), which is a parameter important for ultrafast optical control materials. The obtained |χ(3)

b
b
b
b
| value satisfies an already known relationship between the second- and third-order susceptibilities.
Transversely Excited Atmospheric CO2 Laser with Ultraviolet Preionizer Separated by Optical Window
Authors: Komi Takao , Imada Go , Grigoriu Constantin , Masugata Katsumi , Masuda Wataru , Kiyoshi Yatsui Kiyoshi Yatsui
Published: October 2002

The performance of a Transversely Excited Atmospheric (TEA) CO2 laser with an optical window in front of the preionizer is described. The windows were made of LiF and SiO2. With the LiF window, a maximum laser output energy of 11.6 J/ l (6.2%) was obtained, which was almost the same as that obtained without the window (12.1 J/ l, 6.4%), from a discharge volume of 19 cm3. With the SiO2 window, lasing was not possible. The wavelength range of 110–160 nm was found to be effective for preionization.
Positron Trapping Cross Section and Trapping Efficiency in Plastically Deformed Magnesium
Authors: Mamdouh Abdelrahman Mamdouh Abdelrahman , Emad Badawi Emad Badawi
Published: October 2002

Measurement of positron annihilation lifetime in a pairs of deformed magnesium specimens with deformations of up to 75% are discussed. The lifetime *BAR*τ*BAR* exhibits saturation: for deformations larger than those corresponding to a 15% thickness reduction. The lifetime varies from 231±2 ps for annealed magnesium to 249±2 for dislocation-saturated samples. The trapping cross section and trapping efficiency are calculated.
Influence of Buffer Layers on Lead Magnesium Niobate Titanate Thin Films Prepared by Pulsed Laser Ablation
Authors: Nakamura Takanori , Masuda Atsushi , Morimoto Akiharu , Shimizu Tatsuo
Published: October 2002

Lead magnesium niobate titanate ( Pb[(Mg1/3Nb2/3)0.9Ti0.1]O3; PMN-PT) thin films were prepared on Pt/Ti/SiO2/Si substrates with buffer layers by pulsed laser ablation (PLA). Lead titanate (PT), barium titanate (BT) and barium strontium titanate (BST) were chosen as the materials of the buffer layer. The crystalline structure of the PMN-PT thin films on the buffer layers was a mixture of perovskite and pyrochlore phases. Among these samples, the PMN-PT thin films on the BST buffer layer have the highest perovskite fraction of over 95%. Average dielectric constant of the PMN-PT thin film on the BST buffer layer was about 1200. No serious interdiffusions between the bottom electrode, the buffer layer and the PMN-PT layers were observed.
Write Laser Power Normalization Method for Magneto-Optical Disk Drives
Authors: Hara Shigeji , Ohishi Kan-ichi , Kubo Takahiro
Published: October 2002

Under the ISO/IEC 10090 specification for magneto-optical disks, write conditions including write laser power should be appropriately written on control tracks. However, the definition and measurement method of the write power are not necessarily clear. Satisfactory normalization schemes for the write power should be developed. In this paper we describe the possibility of normalizing the write power of optical disk drives using a typical laser power. The main findings obtained were as follows. (1) Saturation curves normalized by a typical laser power were correlated well in shape in the laser power range in which jitter and error rate are minimum. (2) Our results show the possibility of normalizing the write power of drives using a typical laser power of a calibration disk and the feasibility of a relative value method for facilitating optical disk interchangeability.
Grain Size Control of Diamond Membrane for X-Ray Mask by Use of Fluidized Bed Pretreatment
Authors: Noguchi Hitoshi , Takarada Yoshihiro Kubota
Published: October 2002

Using a fluidized bed for pretreatment of the substrate and changing the nucleation density, we have controlled the grain size of 76-mm-diameter diamond membranes for X-ray lithography, formed by microwave plasma chemical vapor deposition (CVD). The nucleation density ranged from 8.4×105 mm-2 to 3.4×108 mm-2 for pretreatment time ranging from 20 min to 600 min. After pretreatment, we fabricated continuous films. The mean grain size of film fabricated after 600 min of pretreatment was 1/1.4 that of film fabricated after 20 min of pretreatment. The results of evaluation by X-ray diffraction (XRD) and Raman spectroscopy of the films after the two pretreatment times showed the same crystallinity of (111)-textured polycrystalline diamond with low impurity concentrations. A subsequent study of visible light (λ=633 nm) transmittance for free-standing membranes indicated that scattering of incident light was minimized due to the reduced grain size.
Light Emission from Nanometer-Sized Silicon Particles Fabricated by the Laser Ablation Method
Authors: Tetsuya Makimura Tetsuya Makimura , Yasuhiko Kunii Yasuhiko Kunii , Kouichi Murakami Kouichi Murakami
Published: October 2002

Luminescent nanometer-sized silicon particles are fabricated by laser ablation of a silicon target in helium gas. The formation of products is found to be governed by the dynamics of the laser-ablated silicon particles in the gas. The products deposited on silicon substrates exhibit light emission with a peak at 1.6 eV in the air, while 2.1 eV after annealing for 20 min at 800°C in oxygen gas. Applying the laser ablation technique, we demonstrate a novel technique for fabricating silicon particles embedded in a silicon dioxide film. The particles also exhibit visible light emission.
A Clean GaP(001)4×2/c(8×2) Surface Structure Studied by Scanning Tunneling Microscopy and Ion Scattering Spectroscopy
Authors: Masamichi Naitoh Masamichi Naitoh , Akihiko Watanabe Akihiko Watanabe , Akira Konishi Akira Konishi , Satoshi Nishigaki Satoshi Nishigaki
Published: October 2002

We report the results of scanning tunneling microscopy and ion scattering spectroscopy investigation on the structure of GaP(001)4×2/c(8×2) surfaces prepared by ion bombardment and annealing methods. We found that the unit cell of the 4×2 structure consists of two Ga dimers with two dimer vacancies and that the atomic separation in the Ga dimer is about 0.27 ±0.01 nm.
Change in Charging Characteristics of High Polymers due to Plasma Treatment
Authors: Hiromitsu Takeda Hiromitsu Takeda , Yuji Murata Yuji Murata
Published: October 2002

Polymer films of high density polyethylene (HDPE) and Nylon 12 were plasma-treated in Ar gas and the effect of the treatment on their charging characteristics was investigated. After the plasma treatment,the contact angle of each film decreased and films tended to became more negatively charged. The contact angle and the charging characteristics gradually recovered with time and appeared to reach constant values 10 days after the treatment.
Durability Characteristics of Aminopyrene Dimer Molecules as an Emitter in Organic Multilayered Electroluminescent Diodes
Authors: Adachi Chihaya , Kazukiyo Nagai Kazukiyo Nagai , Nozomu Tamoto Nozomu Tamoto
Published: October 2002

We report the structure design of emitter molecules using aminopyrene dimers for obtaining durable organic electroluminescent (EL) diodes. Using eighteen kinds of emitter molecules having a variety of substituents and linking groups, we investigated the durability of the cell structure of the anode/hole transport layer/emitter layer/electron transport layer 2/electron transport layer 1/cathode. We observed that the chemical structures of the emitter molecules strongly influenced the durability of the EL devices under continuous DC operation. We observed no direct relationships between melting point (T
m), glass transition temperature (T
g), ionization potential (I
p), electron affinity (E
a) of emitter layers and EL device durabilities. The effect of the substituent groups of emitter molecules on EL device durability suggests that the chemical stability of the emitter molecules largely influences EL device durability.
Structural and Dielectric Properties of Ba(Ti1-xSnx)O3 Thin Films
Authors: Tsukada Mitsuo , Masashi Mukaida Masashi Mukaida , Shintaro Miyazawa Shintaro Miyazawa
Published: October 2002

Close correlation between the dielectric constant and the degree of
preferential (111) orientation is found for Ba(Ti0.85Sn0.15)O3 ( BTS15)
solid-solution thin films deposited on a Pt/Ti/SiO2/Si(100) substrate by
pulsed laser deposition. It is shown that substrate temperature is the
principal factor which determines orientation and crystalline quality of
the films. Substrate temperatures higher than 700° C are required to
achieve (111) orientation with good crystalline quality. BTS15 films with
strong (111) orientation have large dielectric constant which reaches 2500
at 22° C. These films exhibit a D-E hysteresis loop, but small remanent
polarization of 0.89 µ C/cm2 and coercive field of 3.2 kV/cm are obtained
at 18° C. Films having the composition with lower Sn ratio exhibit larger
remanent polarization. Causal relationships among the dominant film
orientation, crystalline quality and dielectric constant are discussed.
Control of Crystallinity in Sol-Gel Derived Epitaxial LiNbO3 Thin Films on Sapphire
Authors: Nashimoto Keiichi , Hiroaki Moriyama Hiroaki Moriyama , Eisuke Osakabe Eisuke Osakabe
Published: October 2002

Control of crystallinity in solid phase epitaxial growth of LiNbO3 thin films
derived from methoxyethoxide solution on sapphire substrates has been
attempted by investigating growth variables. Crystallization at 700° C for longer
than 30 min was necessary for full crystallization of LiNbO3 thin films, although
the orientations of the LiNbO3 crystal planes parallel to the substrates were
almost independent of crystallization temperature and crystallization time.
Layer-by-layer crystallization and preparation of an ultrathin initial layer have
been found to be important in the growth of high-quality epitaxial LiNbO3 thin
films. X-ray diffraction analysis revealed that perfectly single-plane-oriented
epitaxial LiNbO3 thin films, with rocking curve full width at half-maximum of
less than 0.07°, were produced on sapphire (001) substrates. Refractive index of
2.24 and optical propagation loss of 3.0 dB/cm were achieved.
Influence of Buffer Layer Insertion and Annealing Mode upon Microstructures and Ferroelectric Characteristics of Sol-Gel-Derived Pb(Zrx, Ti1-x)O3 Thin Films
Authors: Doi Hidekazu , Tiba Yoshikazu , Hirayama Akio , Ryu Takahiro , Matsushima Teruji , Hashimoto Mineo , Kudo Daishi , Jyun Saito Jyun Saito , Toshio Watanabe Toshio Watanabe
Published: October 2002

As a continuation of our previous work, PZT films with the Zr/Ti ratio varied
from 40/60 to 70/30 were prepared by a sol-gel method, and the effects of PZT(120/52/48)
buffer layer insertion and the annealing mode were investigated. The
results indicate that, irrespective of the annealing mode, unbuffered PZT films
with a Zr/Ti ratio of 40/60 to 60/40 exhibit (111)-preferred orientation, whereas
buffer layer insertion induces growth with (100) orientation. This is in contrast
to the case of PZT(70/30) film in which growth with (100) orientation is
discernible even when the buffer layer is not inserted. AFM observations reveal
that the PZT films with the buffer layer display slightly smoother surface
microstructures than the unbuffered films. This is more clearly displayed in the
case the film is subjected to RTA. Although the essential features of P-E
hysteresis loops of the films are not significantly affected by the annealing
mode, conventional furnace annealing generally leads to slightly larger remanent
polarization (Pr) than RTA. Pr vs Zr/Ti ratio curves for PZT films with and
without the buffer layer invariably give a peak at Zr/Ti=60/40. Fatigue life
does not markedly improve even with an appropriate choice of the process factors
in the film synthesis, which influence the microstructures and ferroelectric
properties.
Temperature Dependence of Zero Offset of Piezoelectric-Ceramic Cylinder Vibratory Gyroscope
Authors: Abe Hiroshi , Yoshida Tetsuo , Nakamura Hiromichi Kobayashi
Published: October 2002

In this paper, we describe a piezoelectric-ceramic cylinder vibratory gyroscope with
interdigital electrodes. Increasingly stable gyroscopes have been required as
direction sensors of car navigation systems. The temperature dependence of zero
offset is one of the most important characteristics of such gyroscopes. We proposed
an expression for the temperature dependence of zero offset using an
equivalent circuit analysis. The temperature dependence of zero offset is
derived by using the relationship between vibratory imbalances and
temperature dependence of the mechanical quality factor Q
m of the
piezoelectric-ceramic material. The validity of this expression was empirically
proved. By reducing the temperature dependence of the piezoelectric-ceramic
material, we could decrease the temperature dependence of zero offset of the
vibratory gyroscope.
Characteristics of Ultrathin Ferroelectric Liquid Crystal Film and Optical Switching
Authors: Sadahito Uto Sadahito Uto , Hideyo Ohtsuki Hideyo Ohtsuki , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Electrooptic response in a free-standing (FS) ferroelectric liquid crystal film has been studied. The threshold field of the electrooptic effect in the FS film is negligible compared with that in a sandwich cell. Discontinuous dependence of response speed on the applied field is observed in the FS film. The response of FS film can be classified into three types. In order to clarify the switching mechanism, the texture of FS film has been observed. Looped π-walls appear after low-field inversion, while a disclination line at the film surface disappears in the high-field region in which response speed is proportional to E
-1.
Ferroelectric Properties of the PbZrO3–PbTiO3 System
Authors: Takashi Yamamoto Takashi Yamamoto
Published: October 2002

The dielectric and piezoelectric properties of solid solutions with
compositions PbZr1-
x

Ti

x

O3, x=0.200 to 0.750, with an 0.005Nb2O5
additive prepared by modern ceramic technology were investigated,
focusing on the morphotropic phase boundary (MPB, x=0.467).
Relationships between the dielectric, piezoelectric and crystal phases
were compared with results reported by Jaffe et al.. The relative
permittivity (ε
r) at room temperature increased in the composition
range 0.465<x<0.480, corresponding to the MPB. The remanent
polarization (P
r) increased and the coercive field (E
c) decreased in
the rhombohedral phase approaching the MPB from the PZ side.
The values were 41.1 µ C/cm2 and 687.5 V/mm, respectively, at x=0.460.
Also, as the PT content increased, E
c increased on the tetragonal side of
the MPB (x>0.469), resulting in a low P
r. Large electromechanical
coupling factors of k
p=0.690 at x=0.465, k
t=0.534 at x=0.470, k
31=0.415
at x=0.465 and k
33=0.71 at x=0.465 were obtained extremely near the
MPB composition. These values were higher than those obtained by
Jaffe et al.. Also, the frequency constant (F
c) had a minimum value of
1901 Hz·m at x=0.465.
Ferroelectricity and Phase Relations in the System Pb(Yb1/2Nb1/2)O3–PbZrO3
Authors: Masaru Yokosuka Masaru Yokosuka , Ken-ichi Imazeki Ken-ichi Imazeki
Published: October 2002

The phase diagram was determined for the entire composition
range of the system Pb(Yb1/2Nb1/2)O3–PbZrO3. Despite the fact that
both end members Pb(Yb1/2Nb1/2)O3 and PbZrO3 are
antiferroelectric, a ferroelectric phase appeared for a narrow composition
range, and its nature was briefly discussed. The phase diagram was
found to consist of the three phases, paraelectric (PE) cubic,
ferroelectric (FE) tetragonal and antiferroelectric (AFE)
orthorhombic. An insoluble region was also found to exist.
Structural Phase Transition in La-Substituted Pb[(Yb 1/2Nb 1/2) 0.88Ti 0.12]O 3 Relaxor System
Authors: Vin Im Ki , Koh Choo Woong Kil Choo
Published: October 2002

We have investigated the effect of substitution of La2O3 + Yb2O3
to the perovskite solid solution near the composition (PbYb1/2Nb1/2O3)0.88–(PbTiO3)0.12
in the chemical formula (1-x)[(PbYb1/2Nb1/2O3)0.88 (PbTiO3)0.12]–xLaYbO3.
When x = 0.0 and x =0.01, these solid solution have partially disordered
pseudocubic structure and behave as a ferroelectric relaxor. For x ≥0.02,
the character of phase transition changes from a ferroelectric relaxor type to an
antiferroelectric one and the transition temperature surprisingly increases with
LaYbO3 addition. In this composition range, the solid solution displays a
sharp antiferroelectric transition. The effect on the tendency toward
antiferroelecticity with increasing LaYbO3 content is displayed in
restoring of the superlattice reflections due to antiferroelectric order.
From the structural study of ceramic specimen having
various PbTiO3 and LaYbO3 concentration, we have constructed
a portion of phase diagram of pseudoternary PbYb1/2Nb1/2O3–PbTiO3–LaYbO3
system.
Reliability Study of C-Doped AlGaAs/GaAs Heterojunction Bipolar Transistors with Half-Micron-Wide Emitters
Authors: Mochizuki Kazuhiro , Hirata Kohji , Hiroyuki Uchiyama Hiroyuki Uchiyama
Published: October 2002

The reliability of C-doped AlGaAs/GaAs heterojunction bipolar transistors (HBTs) with emitter widths of 0.5 and 0.8 µ m is studied at base-emitter junction temperatures ranging from 240° C to 290° C with an emitter current density of 1.0×105 A/cm2. Although there is no difference between the initial current-voltage characteristics of HBTs fabricated using wet etching and dry etching processes, the bias stress increases the base current of the dry-etched HBTs. The excess base current has an ideality factor of two, which indicates that the damage caused during dry etching produces recombination centers during minority carrier injection. The activation energy for the current gain degradation is found to be 0.89 eV.
Liquid-Phase Epitaxial Growth of GaInAsSb and the Properties of AlGaSb/GaSb/GaInAsSb Separate Absorption and Multiplication Avalanche Photodiodes
Authors: Sun Yuh-Maoh , Jyh-Ming Wang Jyh-Ming Wang , Meng-Chyi Wu Meng-Chyi Wu
Published: October 2002

A high-quality GaInAsSb epitaxial layer can be grown with a hole concentration of 8.5×1015 cm-3 at room temperature and a photoluminescence (PL) full width at half-maximum of 8.5 meV at 10 K. The 10 K PL wavelength peak of Te-compensated GaInAsSb layers shifts toward the high-energy side with increasing electron concentration, which is attributed to the Burstein-Moss effect. The AlGaSb/GaSb/GaInAsSb heterostructure has a very uniform elemental depth profile, sharp heterointerface, and high-quality epitaxial layers. The fabricated separate absorption and multiplication avalanche photodiodes, illuminated with a 1.9-µm-wavelength light source, exhibit a dark current of 55 µ A, a junction capacitance of 4 pF, and a multiplication factor of 9.6 at the reverse voltage of 1.5 V.
Time-Resolved Reflection High-Energy Electron Diffraction Analysis in Initial Stage of 3C-SiC Growth on Si(001) by Gas Source Molecular Beam Epitaxy
Authors: Tomoaki Hatayama Tomoaki Hatayama , Takashi Fuyuki Takashi Fuyuki , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

Initial stages of 3C-SiC growth on Si using cracked C3H8 in gas source molecular beam epitaxy were studied using in situ reflection high-energy electron diffraction. Starting from a Si (001) clean surface showing a (2×1) structure, the surface structure changed in the order of Si(2×1) → structure of mixed Si(2×1) and Si c(4×4) → 3C-SiC with a continuous supply of cracked C3H8. An activation energy of 46.9 kcal/mol was obtained in the initial stage of 3C-SiC growth. After the appearance of 3C-SiC diffraction spots, island structures of 3C-SiC nuclei were observed using a high-resolution scanning electron microscope. Based on these results, growth mechanisms in the 3C-SiC/Si heteroepitaxial system are discussed.
Optical Thickness Evaluation of Separation by IMplanted OXygen (SIMOX) Wafers
Authors: Kajiyama Kenji , Morikawa Yoji , Iaso Hamaguchi Iaso Hamaguchi , Takayuki Yano Takayuki Yano
Published: October 2002

In low-dose SIMOX (Separation by IMplanted OXygen) of SOI (silicon on insulator) structures, the thickness of the surface-Si and buried-oxide layers was evaluated using ellipsometry, reflection and XTEM (cross-sectional transmission electron microscope). Due to the simplicity of the low-dose SIMOX structure, layer thickness could be successfully determined by single-wavelength ellipsometry once the thermal-oxide layer had been etched off. Dislocation density in the surface-Si layer was low, and no Si-islands or Si-pipes were observed in the buried-oxide layer by XTEM. Total errors of measurement and calculation were ≤±1 nm for the surface-Si layer and ≤±2 nm for the buried-oxide layer. These error values were acceptable to guarantee the ≤±5 nm thickness uniformity necessary for VLSI applications.
Surface-Structure-Controlled Heteroepitaxial Growth of 3C–SiC(001)3×2 on Si(001): Simulations and Experiments
Authors: Greene Makoto Kitabatake
Published: October 2002

Mechanistic reaction paths for the heteroepitaxial growth of 3C–SiC on carbonized Si(001) were investigated using a combination of molecular dynamics (MD) simulations and molecular beam epitaxy (MBE) experiments. The stable Si-terminated 3C–SiC(001) surface was found by MD to exhibit a 2×1 reconstruction similar to the Si(001)2×1. The addition of Si adatoms on SiC(001)2×1 results in the formation of a series of missing-dimer-row type reconstructions of h×2 where h=···, 7, 5, 3 with increasing Si adatom coverage. The most stable surface structure is SiC(001)–Si3×2 with a dangling bond density of 0.67 per SiC(001)1×1 unit cell. Analyses by transmission electron microscopy, X-ray diffraction, and electron spin resonance of 1000-Å-thick SiC(001) heteroepitaxial layers grown by MBE on miscut Si(001)–4°[110] at 1050° C as a function of incident C/Si flux ratio J
C/J
Si showed that the highest quality layers were obtained by surface-structure-controlled epitaxy in which in-situ reflection high-energy electron diffraction was used as a feedback signal to adjust J
C/J
Si, during growth to maintain a 3×2 surface reconstruction. A model involving asymmetric growth kinetics parallel and perpendicular to step edges is presented.
Capacitance Modulation from Submicron Domain on Ferroelectric-Semiconductor Media
Authors: Ryoichi Yamamoto Ryoichi Yamamoto , Kazuo Sanada Kazuo Sanada , Shizuo Umemura Shizuo Umemura
Published: October 2002

Reproduction capacitance signal of a ferroelectric-semiconductor disk memory was studied by numerical simulation under an extremely high-density recording condition. Information is recorded by controlling the direction of the ferroelectric polarization which induces the change of depletion-capacitance of the semiconductor substrate. When the spatial wavelength is less than 1 µm, depletion regions connect with each other, which is called the “punch-through” effect. It has been considered that the depletion-capacitance modulation disappears in the “punch-through” state. The present numerical simulation, however, suggested that for the ferroelectric-semiconductor structure, the modulation signal of depletion-capacitance does not disappear even in the “punch-through” state, because there exist island accumulation regions at the semiconductor surface due to the ferroelectric polarization of domains with opposite direction. This result is consistent with previous experimental results. It is suggested that the ferroelectric-semiconductor disk memory has a potential for higher density recording than silicon nitride-silicon disk memories.