bluuebunny/crossref_metadata_2025 huggingface dataset:
Rear Aperture Detection on Magnetostatically Coupled Magnetically Induced Superresolution Medium
Authors: Ken Tamanoi Ken Tamanoi , Keiji Shono Keiji Shono
Published: October 2002

A magnetically induced superresolution (MSR) medium was developed
using magnetostatic coupling. The medium comprises a GdFeCo reading
layer, a SiN intermediate layer, and a TbFeCo writing layer. We
implemented rear aperture detection (RAD) using a transition metal (TM)-rich
reading layer with perpendicular magnetization. We obtained a carrier-to-noise
ratio of 45 dB for a mark length of 0.38 µm. Crosstalk was below
-40 dB, which is low enough for practical use. By measuring the minor
Kerr loop for the sample, on which small domains were written, we
clarified that initialization of the reading layer occurs spontaneously, even
in the absence of a magnetic field.
Enhancement of Electroluminescence Intensity from Dye-Doped Poly(3-Alkylthiophene) Light Emitting Diode with Different Alkyl-Side-Chain Length
Authors: Yutaka Ohmori Yutaka Ohmori , Yasuhisa Hironaka Yasuhisa Hironaka , Masayoshi Yoshida Masayoshi Yoshida , Akihiko Fujii Akihiko Fujii , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Electroluminescent (EL) diodes utilizing poly(3-alkylthiophene) (P3AT) containing fluorescent dyes have been fabricated and their marked enhancement of emission characteristics has been discussed. Enhancement of EL efficiency has been observed for diodes with P3AT doped with PBD (2-(4-biphenylyl)-5-(4- tert-butylphenyl)-1,3,4-oxadiazole), PPCP (1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene) or BPPC (N,N'-bis(2,5-di- tert-butylphenyl)-3,4,9,10-perylenedicarboximide), and more than 500 times higher emission efficiency is obtained in PPCP-doped P3AT. Based on the result of thickness dependence of EL efficiency in PBD-doped P3AT, the layer thickness at which maximum efficiency is obtained is found to be smaller than that in undoped P3AT. The mechanism of emission enhancement by doping of dye molecules into P3AT with different alkyl-side-chain lengths has been discussed in terms of carrier trapping and the energy band diagram.
Direct Bonding between InP Substrate and Magnetooptic Waveguides
Authors: Yokoi Hideki , Mizumoto Tetsuya , Maru Koichi , Nobutaka Fuke Nobutaka Fuke , Yoshiyuki Naito Yoshiyuki Naito
Published: October 2002

Wafer direct bonding was demonstrated between InP and magnetooptic materials. The effects of chemical treatment of two wafers before placing them into contact were investigated in order to enhance the durability of the bonded wafers through the various device fabrication processes. Phosphoric acid etching at a low temperature proved to be the most suitable treatment for the bonding between InP and gadolinium gallium garnet Gd3Ga5O12. In the case of this treatment, the bonding was studied between a planar InP substrate and magnetooptic waveguides on the garnet films.
Further Study of the Generation Technique of High-Speed Liquid Jets and Related Shock Wave Phenomena Using a Helium Gas Gun
Authors: Shi Hong-Hui , Kazuki Koshiyama Kazuki Koshiyama , Motoyuki Itoh Motoyuki Itoh
Published: October 2002

An extensive experimental investigation was carried out with the aim of understanding the hydrodynamics involved in generating a pulsed high-speed liquid jet. A wire cutting device for measuring the projectile velocity was installed at the exit section of the launch tube so that the impact velocity of projectiles and the velocity of liquid jets could be measured simultaneously. The projectiles were made from low-density polyethylene, which was expected to reduce the rebound in the impact and thus to create a a high nozzle pressure for a longer duration. The jets were generated using different combinations of nozzle diameters, impact methods, nozzle back side geometries, light and heavy projectiles, etc. Based on the obtained relationships between the jet velocities and projectile velocities, the hydrodynamic processes occurring in the nozzles were clarified to some extent. Besides the liquid jet experiment, the projectile motion along the launch tube, in-tube shock wave and discharging shock wave were also examined in order to improve the performance of the gas gun and to calibrate the laser system. The results of theoretical analyses and numerical work were applied to interpret the experiment results.
AlGaInP/GaP Light-Emitting Diodes Fabricated by Wafer Direct Bonding Technology
Authors: Chang Shoou-Jinn , Sheu Jinn-Kong , Su Yan-Kuin , Jou Ming-Jiunn , Chi Gou-Chung
Published: October 2002

An AlGaInP/GaP light-emitting diode was fabricated by wafer direct bonding technique. The device was grown on GaAs substrate by metalorganic vapor phase epitaxy (MOVPE). After bonding the n-GaP substrate on top of the epitaxial layers, the original GaAs substrate was removed. The luminous intensity of this wafer-bonded device is around 60 mcd/S
r
at an operation current of 20 mA. It is about two times brighter than the conventional device with absorbing GaAs substrate. The large lattice constant mismatch (3.6%) between wafer-bonded GaP substrate and GaInP did not degrade the device characteristics.
Change in Temperature Coefficient of Resistance of Heavily Doped Polysilicon Resistors Caused by Electrical Trimming
Authors: Kotaro Kato Kotaro Kato , Terukazu Ono Terukazu Ono
Published: October 2002

The change in the temperature coefficient of resistance (TCR) of heavily doped polysilicon resistors caused by electrical trimming has been analyzed based on the melting-segregation model. The model reveals that the TCR of the boundary layers in a polysilicon resistor changes with trimming while that of grains remains the same. The theoretical expression for the change in the TCR of polysilicon resistors agrees well with the wide range of experimental data. The structures of the boundary layers and grains are discussed from the viewpoint of the TCR.
Premastered Optical Disk by Superresolution Using Rear Aperture Detection
Authors: Kasami Yutaka , Yasuda Kouichi , Ono Masumi , Atsushi Fukumoto Atsushi Fukumoto , Masahiko Kaneko Masahiko Kaneko
Published: October 2002

Premastered optical disk by superresolution (PSR) using rear aperture detection (RAD) has been realized. The PSR disk has a chalcogenide material. Using PSR by RAD with a current CD system, we demonstrated the feasibility of increasing both the linear density and the track density of read only memory (ROM) optical disks. By superresolution in the linear direction, a high C/N of 47 dB was obtained for a pit length of 0.3 µm which is beyond the optical limit. Furthermore, by superresolution in the track direction, a low crosstalk of -38 dB and a wider margin of radial skew angle compared to conventional detection were obtained for a track pitch of 1.1 µm.
Theoretical Study of Resonant Tunneling Diodes with Impurity Ions Located in Wells
Authors: Nobuya Machida Nobuya Machida , Kazuhito Furuya Kazuhito Furuya , Mike Gault Mike Gault
Published: October 2002

Transmission characteristics of resonant tunneling diodes (RTDs) with impurity ions in wells are analyzed using a two-dimensional model. The impurity ions are found to result in the transmission energy spectrum having a double-peak shape with intrinsic and impurity-assisted peaks. The appearance of the impurity-assisted peak explains previously reported experimental observations. The height of the impurity-assisted peak depends on the concentration of impurity ions in the well. Impurity ions in the well may broaden the intrinsic peak width, which should be taken into consideration in the estimation of the electron coherence using the resonance energy width of RTDs.
“Backward Diode” Characteristics of p-Type Diamond/n-Type Silicon Heterojunction Diodes
Authors: Phetchakul Toempong , Kimura Hideki , Akiba Yukio , Tateki Kurosu Tateki Kurosu , Masamori Iida Masamori Iida
Published: October 2002

Rectification characteristics obtained for p-type diamond/n-type silicon heterojunctions have been studied. The current–voltage (I–V) characteristics of p-n heterojunctions show the same manner of rectification as in a backward diode. Forward current depends on both the concentration of boron atoms in polycrystalline diamond and the ambient temperature. The temperature dependence of I–V characteristics indicated that forward and reverse currents are mainly ascribed to diffusion and tunnelling currents, respectively. This current flow mechanism is peculiar to a backward diode. A simplified energy band model was proposed to explain the current transport mechanism in these heterojunctions. The experimental results can be explained with the aid of the proposed energy band model.
Source and Drain Parasitic Resistances of Amorphous Silicon Transistors: Comparison between Top Nitride and Bottom Nitride Configurations
Authors: Rolland A. , Richard J. , Kleider J. P. , Mencaraglia D.
Published: October 2002

The source and drain parasitic resistances of amorphous silicon based thin film transistors (aSi:H TFT) are investigated using a very simple TFT model including a parameter extraction method. We show that this method provides an accurate measurement of these resistances and clearly explains their influence on the apparent field effect mobility µ a of the TFTs. We compare the parasitic resistances of TFTs for the top nitride (TN) and bottom nitride (BN) configurations and we show that the usual different performances observed on the two configurations can be mainly attributed to the differences in the parasitic resistances.
Enhanced Metalorganic Chemical Vapor Deposition Titanium Nitride Film Fabricated Using Tetrakis-Dimethylamino-Titanium for Barrier Metal Application in Sub-Half-Micron Technology
Authors: Wang Chin-Kun , Liu Lu-Min , Liao Marvin , Lin Huang-Chung Cheng
Published: October 2002

Enhanced metalorganic chemical vapor deposition (MOCVD) titanium nitride (TiN:C) film with low resistivity (<700 µ Ω· cm) has been fabricated by thermal decomposition of tetrakis-dimethylamino-titanium (TDMAT; Ti[N(CH3)2]4). Enhancement is carried out by in-situ N2 plasma treatment of as-deposited TiN:C film and the enhanced TiN:C film has good stability: less than 4% increase in film resistivity after exposure to air for 24 days. The amount of oxygen absorbed in this enhanced TiN:C film after air exposure, determined by Auger electron spectroscopy (AES) was significantly reduced. This enhanced MOCVD TiN:C film has been successfully applied to sub-half-micron devices. A void-tree tungsten plug (W plug) for sub-half-micron holes can be achieved. Good barrier performance and low contact/via resistance have also been demonstrated.
Single-Crystal Switching Gates Fabricated Using Cuprate Superconductors
Authors: Tachiki Tsutomu Yamashita
Published: October 2002

We propose new switching gates based on layered structures of high-T
c superconductive single crystals. The operation principle of the proposed gate is similar to that of Josephson junction switches but its size is smaller and its speed is faster than those of Josephson junctions. The proposed switching gates consist of a gate current pass parallel to the c-axis of the single crystal. The gate current is controlled by a magnetic flux induced by input current. The area of the gate is less than 1 µ m2. The minimum switching time τ s is estimated as \cong10-13 s. The gate can be used as a memory cell and a flux flow amplifier. As the proposed gate uses a single crystal the noise figure should be low if the crystal used is of high quality.
Mechanism of a Tuning Operation of a Ti:Sapphire Laser by Injection-Seeding
Authors: J. Vasa Nilesh , Tatsuo Okada Tatsuo Okada , Mitsuo Maeda Mitsuo Maeda , Osamu Uchino Osamu Uchino
Published: October 2002

We report a limiting mechanism which determines a spectral tuning range of a pulsed Ti:sapphire laser by injection-tuning. An analytical model has been developed to estimate an attainable tuning range based on the theory of Q-switched operation. It was found that a maximum achievable tuning range was limited between 740 and 840 nm without using any intracavity tuning elements in the Ti:sapphire laser by injection-tuning. These results were compared with experimental results.
KrF-Laser-Induced Fiber Bragg Gratings: Formation Characteristics and Cutback Measurement
Authors: Mizunami Toru , Sanjay Gupta Sanjay Gupta , Teruo Shimomura Teruo Shimomura
Published: October 2002

The formation characteristics of fiber Bragg gratings were studied by using the side-writing holographic method with a 248 nm injection-locked narrow-band KrF excimer laser. Type I gratings with reflectivity as high as 99% were formed in hydrogen-loaded fibers by multiple-pulse exposure. Type II gratings with the maximum reflectivity of 90% were also fabricated. The characterization of fiber gratings by the cutback method is demonstrated. Using this method, we determined the effective grating length and calculated the magnitude of photoinduced index change. Chirp characteristics of the gratings were also studied.
Blue Electroluminescence Mechanism of Polyester Derivative Blend Films
Authors: Peng Junbiao , Yu Byung-Yong , Pyun Chong-Hong , Jin Chang-Hong Kim
Published: October 2002

A new polymer of polyester derivative (PE) blend with poly(N-vinycarbazole) (PVK) and compound of PBD at various weight ratio were used as emitter in unilayer electroluminescence (EL) devices with indium cathode. Analyses of fluorescence and EL spectra imply common emission energy states are formed in the blend films, by which to explain the possibility of maximum EL efficiency in blend films higher than that in either of PE and PVK. The PL and EL spectra show the maximum emission band shifts red slightly between 430 nm and 450 nm as increasing the ratio of PE, meanwhile the half width increases and a new peak around 525 nm appears. The new peak is confirmed originating from the dimer formed by coupling of interchains in polymer PE. Both of PE and PVK can give rise to PL emission under UV light. The origin of PL and EL emission is analysed.
Experimental Considerations on the Piezoelectric Vibratory Gyrosensor Using a Trident Tuning-Fork Resonator
Authors: Akira Satoh Akira Satoh , Kazumasa Ohnishi Kazumasa Ohnishi , Katsutoshi Sakurai Katsutoshi Sakurai , Yoshiro Tomikawa Yoshiro Tomikawa
Published: October 2002

This paper concerns the piezoelectric vibratory gyrosensor using a trident tuning-fork resonator characterized by high stability. In the first part of this paper, the methods of adjusting the resonance frequencies are discussed. Then the investigations to compensate the imbalance in a trident tuning-fork resonator are shown. Moreover, we constructed an experimental gyrosensor based on these results, using differential detection to eliminate the leakage output signals. A miniature piezoelectric vibratory gyrosensor with superior linearity could be achieved.
Compensation Effects of Crystals and Liquid Crystals in Polarizing Optical Microscope
Authors: Ding Jiandong , Zhu Junxiang , Hanfeng Fang Hanfeng Fang , Yuliang Yang Yuliang Yang
Published: October 2002

This paper investigated the effect of a tilting compensator on the anisotropic objects with the radial director configuration in a polarizing optical microscope under orthoscopic observation. The polymer spherulites of poly (ethylene oxide) (PEO) and the radial liquid crystal (LC) droplets in a polymer dispersed liquid crystal (PDLC) film were observed, on behalf of two-dimensional (2D) and three-dimensional (3D) anisotropic entities, respectively. Calculated birefringence patterns found good agreement with the experimental polarizing micrographs. Besides the well-known Maltese cross, the so-called depth-induced light extinction (DILE) bands and corresponding compensation behaviors were investigated in the LC droplets. According to the theoretical and experimental studies, we have revealed plausibly the detailed characteristics of the compensation effects in the 2D and 3D anisotropic objects and the striking differences between them. Some applications of the compensation effect were further pointed out.
Nanometer-Sized Phase-Change Recording Using a Scanning Near-Field Optical Microscope with a Laser Diode
Authors: Hosaka Sumio , Shintani Toshimichi , Miyamoto Mitsuhide , Hirotsune Akemi , Terao Motoyasu , Yoshida Masaru , Fujita Kouichi , Kämmer Stefan
Published: October 2002

We present for the first time a nanometer-sized phase-change recording using a scanning near-field optical microscope (PC-SNOM recording). The recording experiments were performed with a SNOM using a 785-nm-wavelength semiconductor laser diode, shear force detection for gap control and reflected light detection for observing the domains (reading). The recording media of ZnS·SiO2(20 nm)/GeSbTe(30 nm)/ZnS·SiO2(150 nm)/polycarbonate substrate were used. The writings were done at laser powers of 8.4–7.3 mW in the probe for pulse widths of 5 or 0.5 ms. As a result, we obtained a minimum recorded domain size of 60 nm in diameter. This size shows a potential to achieve an ultrahigh density PC-SNOM recording with about 170 Gb/in2. A possibility of achieving high speed readout for the future data storage is also discussed.
Morphology Control of Films Formed by Atmospheric-Pressure Chemical Vapor Deposition Using Tetraethylorthosilicate/Ozone System
Authors: Adachi Motoaki , Okuyama Kikuo , Fujimoto Toshiyuki , Sato Jun-ichi , Muroyama Masakazu
Published: October 2002

The effects of the reaction time of gas-phase intermediates, t
r, initial concentrations of TEOS (C
TEOSin) and O3 (C
O3in), and O3 concentration on a substrate C
O3s, on film formation by atmospheric-pressure chemical vapor deposition using tetraethylorthosilicate (TEOS) and ozone ( O3) were experimentally investigated. These four deposition parameters were altered by varying the merge position of TEOS/He and O3/O2 mixtures and the substrate position in the reactor. The structure of the intermediates was estimated from the chemical analysis of nanometer-sized particles generated during the film formation. The flow shape, the substrate dependence, and the chemical structure of films depended mainly on C
TEOSin and C
O3in, but were independent of C
O3s. The parameter t
r had little effect on the flow shape and substrate dependence. The intermediates that led to the formation of films with excellent flow shape and a small amount of water contained a large amount of carbon.
Morphology of Carbon Nanotubes Prepared by Carbon Arc
Authors: Zhao Xinluo , Wang Miao , Masato Ohkohchi Masato Ohkohchi , Yoshinori Ando Yoshinori Ando
Published: October 2002

Carbon nanotubes were obtained as deposits on the cathode of carbon arc in He and CH4 gases. The morphology of carbon nanotubes was observed by scanning electron microscopy of the top surface of the cathode deposit, and was found to change with evaporation conditions. The variation of carbon nanotube morphology was more marked for the case of evaporation in CH4 gas than that in He gas. Thick carbon nanotubes embellished with a number of nanoparticles were obtained on the cathode of carbon arc under the conditions of high CH4 gas pressure and high dc arc current.
Thermodynamic Interpretation of the Martensitic Transformation in Ultrafine γ-Fe(N) Particles
Authors: Zhao Xinqing , Liang Yong , Hu Zhuangqi , Liu Baixin
Published: October 2002

Face centered cubic (fcc) γ-Fe (5.9–10.4 at.%N) ultrafine particles ranging in size from 30 to 100 nm were prepared at room temperature by laser induced pyrolysis of Fe(CO)5 and NH3. It is found that these austenitic particles did not transform to martensite when subsequently quenched to 77 K or 4.2 K, which is greatly lower than the martensite-start temperature of the bulk alloy with the same composition. Many planar defects, which can serve as the favorable martensitic nucleation sites in bulk austenite alloy, have been observed in these particles. Taking into account the size effect of the ultrafine particles on the martensitic transformation, a modification for the conventional martensitic transformation has been made to interpret the stabilization behavior of the ultrafine γ-Fe(N) particles. It is indicated that the strengthening of the particles due to the reduction of the particle size and refinement of grain size may play important roles in both inhibiting the homogeneous nucleation and martensitic transformation occurred in the ultrafine particles.
Temporal Behavior of Charged Particles in a Radio Frequency Afterglow Plasma Containing Negative Ions
Authors: Ohtsu Yasunori , Takuma Seki Takuma Seki , Hiroharu Fujita Hiroharu Fujita
Published: October 2002

Temporal behavior of charged particles in pure He and He–SF6 radio frequency (rf) afterglow plasmas has been experimentally clarified for various SF6 gas concentrations (1, 25, 50%). The electron density in the pure He plasma increased just after the rf power was switched off, unlike in a pure Ar plasma, and then decreased slowly. The increase was probably due to collisional ionization of metastable He atoms. The electron density in the He–SF6 plasmas decreased exponentially. This was due to electron attachment to various molecules in the afterglow plasma.
Analysis of Inductively Coupled Electrodeless Discharge by Equivalent Circuit
Authors: Yoshio Watanabe Yoshio Watanabe
Published: October 2002

An equivalent circuit model for inductively coupled electrodeless discharge including an excitation coil is introduced. The validity of the model is verified by an experiment using a simulation tube. By comparing the experimental data of applied voltage and current of the excitation coil with calculation by the model, plasma conductivity and induced discharge current in the inductively coupled electrodeless discharge are estimated. First, the distribution shape of plasma conductivity is estimated. Then, plasma conductivity at the axis, σ0, is approximated by the following equation for the employed discharge tube. σ0=0.29i
D
1.54 S/m, where i
D is induced discharge current in A(rms)/m.
Effects of Axial Magnetic Field and Faraday Shield on Characteristics of RF Produced Plasma Using Spiral Antenna
Authors: Shunjiro Shinohara Shunjiro Shinohara , Seiji Takechi Seiji Takechi , Yoshinobu Kawai Yoshinobu Kawai
Published: October 2002

Influences of the axial magnetic field and Faraday shield on the performance of RF produced plasma using a spiral antenna are investigated. The RF power and filling pressure dependences, antenna-plasma coupling, Ar line intensities and spatial profiles of plasma parameters are studied. With the magnetic field and/or without a Faraday shield, the threshold input power for plasma initiation is lowered and the antenna-plasma coupling is improved. In addition, a collisionless heating mechanism is suggested. With the increase in the applied magnetic field, the ion saturation current increases and shows a peaked radial profile; in the low-pressure range it shows a nearly flat axial profile.
Electron Swarm Parameters Measured Using Photoelectrons Induced by a Pulse Laser
Authors: Takeki Sakurai Takeki Sakurai , Yoshiyuki Ito Yoshiyuki Ito , Tetsuhito Ueda Tetsuhito Ueda , Yukio Inoue Yukio Inoue , Hirokazu Hori Hirokazu Hori
Published: October 2002

Electron swarm parameters such as drift velocity and ionization coefficient are measured using photoelectrons induced by a pulse laser. In order to measure parameters in a wide region of E/p, a pulsed dc voltage synchronized with the pulse laser is applied between electrodes with a pure configuration to keep the electric field uniform. Dynamic behavior of electrons is observed as a transient waveform of an induced current. From the analysis of the waveform, the drift velocity and the ionization coefficient in helium gas can be obtained at E/p up to 500 and 4000 V/cm·Torr, respectively. Further experiments are performed using an actual discharge tube or a gas mixture of halogen and helium. The results are discussed in comparison with those obtained with a pure configuration of electrodes.
Determination of Ionization Cross Section for Argon Metastable-Metastable Collision by Means of Afterglow Technique
Authors: Sugawara Tomio Okada
Published: October 2002

Subtracting the energy loss rates of electrons from the decay rate of electron temperature in an argon afterglow at pressure 133 Pa (Ar), we have separated the energy gain of electrons, which was assumed to be due to superelastic collisions and energetic electrons created by the metastable-metastable ionizing collisions. The cross section obtained has a value between (1.30±0.11)×10-17 m2 and (1.40±0.12)×10-17 m2, which is greater than the cross section for collisions between unexcited argon atoms.
Three-Track Readout Method Using Two Offset Beams
Authors: Dobashi Hisanobu , Takaya Tanabe Takaya Tanabe , Manabu Yamamoto Manabu Yamamoto
Published: October 2002

A high-data-transfer-rate, high-track-density optical recording method using two offset beams to read the data on three tracks was investigated. One beam is offset towards the center track from the center of a side track. Therefore, the readout signal amplitude read from the side track is twice as large as that from the center track. The other beam is offset in the same way. An algorithm was developed to obtain the data from three tracks by using the readout signals from two offset beams. Using this algorithm, data can be retrieved simultaneously from three tracks with a one-to-one dependence between the amplitude levels and the data. This method also offers narrow-track-pitch recording without the need for additional crosstalk cancellation. Computer simulations and experimental results show that this method can achieve three-times-higher data transfer rates and 28%-larger recording density than conventional one-beam systems.
A Ceramic Plasma Torch for Determining Silicon Content in HF Solutions by Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Matsubara Atsuko , Kojima Hisao , Toshihiko Itoga Toshihiko Itoga , Keiichi Kanehori Keiichi Kanehori
Published: October 2002

A ceramic plasma torch has been developed for plasma spectrometers–such as an inductively coupled plasma atomic emission spectrometer (ICP-AES) or an inductively coupled plasma mass spectrometer (ICP-MS)–used to measure trace amounts of Si in HF solutions. Pyrolytic-boron nitride (PBN) and alumina are studied as ceramic torch materials. The PBN torch can be used when the HF concentration is low; however, it cannot be used when the HF concentration is high since contamination of B due to thermal decomposition is significant. When the alumina torch is used, the background spectrum of Si can be decreased to 1/65 of that obtained when using a conventional torch–this increment corresponds to less than 0.2 µg/m l of Si and a 1-µg/m l Si solution can be determined with a relative standard deviation of about 8% even at 10% (v/v) HF concentration.
Observation of the Initial Stage of Ion Assisted Deposition Films Using a Rotating-Analyzer Ellipsometer
Authors: Shibuya Takehisa , Kawabata Shuichi , Yoshizawa Hitoshi , Suzuki Satoshi , Naoji Amano Naoji Amano , Hideshi Yokota Hideshi Yokota
Published: October 2002

We have equipped an ion assisted deposition (IAD) system with a rotating-analyzer ellipsometer for in situ monitoring of the deposition process. The sensitivity of the measurements of the initial stage of deposition varies greatly with the ellipsometric parameters of the substrate. We propose the optimum conditions for the SiO2/Si substrate system for the observation of the initial stage of gold film deposition. The deposition of gold films on optimized silicon oxide substrates was observed in situ using the rotating-analyzer ellipsometer. The growth curves for the gold films were different from those for continuous layer growth in the initial stage. The critical thickness at which the growth mechanism became continuous layer growth varied with the ion current density of the IAD. The ion current density for the minimum critical thickness of gold films had an optimum value of 100 µA/cm2.
Partial-Response Maximum-Likelihood Channel for Mark Edge Recording on Magneto-Optical Disks
Authors: Taguchi Masakazu , Itakura Akihiro , Fujita Yoshihide , Haruhiko Izumi Haruhiko Izumi , Michio Matsuura Michio Matsuura
Published: October 2002

We have developed a partial-response maximum-likelihood (PRML) read channel for mark edge recording on magneto-optical disks. In this paper, we report the results of a computer simulation and an actual experiment using this method and compare them with those of a conventional (level slice [bit-by-bit]) detection method in a leading/trailing-edge-independent reproduction. The PRML read channel can decrease the error rates of signal detection in terms of two factors (phase margin characteristics and error rate characteristics of the carrier-to-noise ratio [C
N
R]). We found that the PR(1, 1) ML detection method improved the C
N
R by 1.7 dB over the conventional detection method. With these improvements, we achieved a 30% phase margin at a density of 0.57 µm/mark ( 0.43 µm/bit). Therefore, we improved the capacity of MO disks using the PRML read channel, which decreased the error rates of signal detection for mark edge recording.
Majority-Carrier Capture Cross Section of Amphoteric Nickel Center in Silicon Studied by Isothermal Capacitance Transient Spectroscopy
Authors: Shuji Tanaka Shuji Tanaka , Kaiji Matsushita Kaiji Matsushita , Hajime Kitagawa Hajime Kitagawa
Published: October 2002

Isothermal capacitance transient spectroscopy (ICTS) has been used to measure majority-carrier capture cross section of nickel centers in silicon. Capture cross sections obtained are temperature-independent with values of 3.2×10-17 cm2 for electron capture at the nickel acceptor center in n-type silicon and 1.8×10-16 cm2 for hole capture at the nickel donor center in p-type silicon. These capture cross sections are associated with the neutral capture of the majority carriers at the amphoteric nickel centers.
Lasing Operation of InGaAsP-Based InGaAs/GaAs Vertical-Cavity Surface-Emitting Lasers with a Strain-Compensated Active Region
Authors: Shinoda Kazunori , Hiramoto Kiyohisa , Misuzu Sagawa Misuzu Sagawa , Kazuhisa Uomi Kazuhisa Uomi
Published: October 2002

We demonstrate the first lasing operation of InGaAsP-based 0.98-µm-range vertical-cavity surface-emitting lasers (VCSELs). The laser consists of a high reflectivity 45.5-pair InGaP/GaAs multilayer reflector, a strain-compensated InGaAs/InGaAsP triple-quantum-well active region, and a 10-pair SiO2/ TiO2 multilayer reflector. The 11-µm-diameter VCSEL exhibited a threshold current of 1.7 mA and a low threshold voltage of 1.6 V under pulsed operation at room temperature. Continuous-wave operation was also obtained with a threshold current of 2.8 mA.
Two-Photon Absorption in Tin Dioxide Single Crystal at 532 nm
Authors: Watanabe Yuichi , Ohnishi Masato , Masashi Nakazawa Masashi Nakazawa , Toshio Tsuchiya Toshio Tsuchiya
Published: October 2002

Single crystals of tin dioxide synthesized by a hydrolysis reaction of stannic chloride are submitted to open-aperture Z-scan measurements at 532 nm. The two-photon absorption coefficient of the crystal is determined-to be 7.6±1.3 cm/GW. The value is larger by about three times than that predicted theoretically. One of the reasons for the discrepancy is given as the applicable limit of the theory in which a two-band model is assumed in the analysis.
Electrical Properties of ZnO Varistors Prepared by Microwave Sintering Process
Authors: Chen Chang-Shun , Kuo Cheng-Tzu , Lin I-Nan
Published: October 2002

Microwave sintering processes were observed to substantially enhance the densification rate for ZnO varistor materials. Samples microwave sintered at 900–1200° C for 10 min reached the same high density as those conventionally sintered at the same temperature for 60 min. A similar tendency was observed for the grain size. Prolonged microwave sintering, however, resulted in fast grain growth and degraded electric field–current density ( E–J ) properties. Capacitance–voltage ( C–V ) analysis indicated that the degradation in E–J behavior primarily resulted from the decrease in grain boundary barrier height. The modification of the grain boundary electrical properties, in turn, is ascribed to the loss of volatile Bi species along the grain boundaries.
Optical Disc Track Pitch Variation Measurement Using Two Readout Beams
Authors: Kurokawa Kotaro , Eguchi Naoya , Arai Masayuki , Shin Masuhara Shin Masuhara , Hiroshi Ooki Hiroshi Ooki
Published: October 2002

At present high-density optical discs have narrow track pitch values, and hence it is necessary not only to verify the precision of the track pitch, but also to determine the degree of track pitch variation. Track pitch variation (T
P
V) is commonly measured using scanning electron, laser scanning and scanning tunneling microscopies. However, these methods are time consuming and it is difficult to take T
P
V readings from large areas of the disc. We developed a T
P
V measurement system based on an optical disc player with two readout beams, and using this system we can rapidly measure the T
P
V over the whole disc surface. In this paper, we describe our T
P
V measurement system and present the results of T
P
V measurements taken from a disc containing continuous grooves with a track pitch of 0.84 µm. We found that the T
P
V of these grooved discs ranged from 30 nm to 100 nm peak-to-peak (pk-pk) with a typical value of 40 nm pk-pk. The measurement resolution of our instrument is about 10 nm pk-pk.
Crystal Growth and Some Properties of LuB4, LuAlB4, and Lu2AlB6
Authors: Okada Shigeru , Yu Yang , Lundström Torsten , Tanaka Kunio Kudou
Published: October 2002

Crystals of LuB4, LuAlB4, and Lu2AlB6 were grown by the high-temperature aluminium solution method using lutetium oxide and crystalline boron powders as starting materials. The growth conditions for obtaining single crystals of relatively large size were investigated. The as-grown LuB4, LuAlB4, and Lu2AlB6 crystals were subjected to chemical analysis and measurements of unit cell parameters. The Vickers microhardness and electrical resistivity of the crystals were measured, and oxidation at high temperature in air was studied. Average values of Vickers microhardness (Hv) and electrical resistivity (ρ) determined for LuAlB4 and Lu2AlB6 single crystals are as follows: for LuAlB4 Hv=14.0(±0.6) GPa, ρ=86(±6) µ Ω· cm, and for Lu2AlB6 Hv=18.9(±0.7) GPa, ρ=31(±3) µ Ω· cm. The oxidation of LuB4, LuAlB4, and Lu2AlB6 crystals begins to occur at about 590° C, 960° C and 1030° C, respectively. The final oxidation products of LuB4 include LuBO3 and probably amorphous B2O3 or H3BO3. However, the oxidation products of LuAlB4 and Lu2AlB6 crystals were not detected by powder X-ray diffraction, probably due to insufficient amounts of these oxidation products.
Growth Rate and Surface Morphology of Diamond Homoepitaxial Films on Misoriented (001) Substrates
Authors: Tsuno Takashi , Shiomi Hiromu , Kumazawa Yoshiaki , Shin-ichi Shikata Shin-ichi Shikata , Shin-ichi Akai Shin-ichi Akai
Published: October 2002

Homoepitaxial films were grown on misoriented diamond(001) substrates using microwave plasma-assisted chemical vapor deposition with a methane and hydrogen gas mixture. The dependence of growth rate and surface morphology on methane concentration, substrate temperature and off-angle was investigated. The growth rate dependence was significant for a growth at a high substrate temperature (1000° C) and low methane concentration (1%), suggesting the surface migration distance of the nanometer order. A flat surface was observed macroscopically and microscopically for films grown on off-substrates at a high substrate temperature and low methane concentration.
Pattern Formation of Sputtered Films by Deposition through Mask
Authors: Toshinari Yamazaki Toshinari Yamazaki , Yasuyuki Yoshino Yasuyuki Yoshino , Toshio Yoshizawa Toshio Yoshizawa , Tatsuo Yamabuchi Tatsuo Yamabuchi , Kiyoshi Terayama Kiyoshi Terayama , Toshiharu Shimazaki Toshiharu Shimazaki , Takashi Mizuguchi Takashi Mizuguchi
Published: October 2002

The thickness of the film near the edge of a film pattern formed by sputter deposition through a mask is not uniform, because of the shadowing effect of the side wall of the mask edge. When the effect is large, a sharp pattern can not be obtained. In order to clarify the precision or the sharpness of the film pattern, the distribution of the film thickness near the pattern edge was measured. It was found that the sharpness depended on the position of the pattern edge and the attitude of the side wall of the mask. A mask with bridges was contrived for the formation of an isolated space in a film, and the film deposition under the bridge was observed. It was found that the ratio of the gap between the substrate and the bridge to the bridge width must be larger than 1.0 for the thickness under the bridge to be greater than half the full thickness.
Transmissivities of Radiation Beams and Particle Beams in Multicomponent Mixed Materials
Authors: Ryusuke Tsuji Ryusuke Tsuji , Shin-ichi Fukuda Shin-ichi Fukuda
Published: October 2002

The radiation and particle beam transmissivity in multicomponent mixed (n components) materials of nonzero grain size is studied by a statistical method. The dependence of the beam transmissivity on the grain size is also reported. The beam transmissivity at a distance L from the source is represented as { p
1 exp
(-d/λ1) + p
2 exp
(-d/λ2) + …+ p

n
exp
(-d/λ
n
) }
L/d
in one dimension, where p

i
is the volumetric ratio of material i (1≤i≤n) in mixed materials, λ
i
the mean free path of beam particles in material i (1≤i≤n), and d the grain size. The expression of the beam transmissivity is obtained by a similar statistical method for the case in which volumetric ratios, mean free paths and the grain size are functions of the distance from the source.
Influence of Exterior Corona on Discharge Voltage of Small Gap in SF6 Gas under Pulse Voltage
Authors: Kamatani Humihiro , Watabe Katunori , Mitsuyoshi Onoda Mitsuyoshi Onoda , Hiroshi Nakayama Hiroshi Nakayama
Published: October 2002

The effect of a corona initiated from a needle electrode,   which is located near a sphere electrode keeping apart from a plane electrode,on the discharge voltage of the sphere-plane gap under pulse voltages in SF6 gas was investigated . The condition of corona initiation and development depended on the resistance which was connected to the high voltage. With increase in the resistance,the discharge voltage increased considerably and reached a maximum at about 5 M Ω for a pulse rise time of 0.5 µs.
Patterned Emission in Organic Electroluminescent Device Using Photodecomposition of Polysilane Film by UV Light
Authors: Hiramoto Masahiro , Yoshimasa Sakata Yoshimasa Sakata , Masaaki Yokoyama Masaaki Yokoyama
Published: October 2002

Utilizing the photochemical phenomenon that hole transporting polysilane film is converted to an insulator by ultraviolet (UV) light irradiation, patterned emission from a single-layered organic electroluminescent (EL) device composed of hole transporting polysilane film with molecular dispersion of a laser dye and an electron transporting molecule was demonstrated as imaged using UV irradiation through a photomask.
Diamond Film Formation by OH Radical Injection from Remote Microwave H2/H2O Plasma into Parallel-Plate RF Methanol Plasma
Authors: Ikeda Masanobu , Mizuno Etsuko , Hori Masaru , Goto Toshio , Yamada Koji , Hiramatsu Mineo , Nawata Masahito
Published: October 2002

Diamond film was successfully synthesized for the first time using a parallel-plate radio-frequency (RF 13.56 MHz) methanol ( CH3OH) plasma assisted by injection of hydrogen (H) and hydroxyl (OH) radicals generated by microwave H2/ H2O plasma. OH radical, in addition to H radical, injection into RF CH3OH plasma enhanced selective diamond growth and selective etching of the nondiamond phase. The effects of OH radical injection on the initial and growth stages of the diamond formation were investigated by changing H2O partial pressure in the microwave plasma. It was found that OH radical injection into RF CH3OH plasma enhanced the growth of diamond in the initial stage.
Response of a Composite Resonator under Pulse Excitation: A Numerical Study
Authors: Barnana Pal Barnana Pal
Published: October 2002

The response of a one dimensional ultrasonic composite resonator due to the excitation by carrier frequency repeating pulses is evaluated on the basis of the “propagating wave” model. The carrier frequency pulse train is considered as the superposition of an infinite number of continuous waves having frequencies and amplitudes given by its Fourier components. Among them, only those having frequencies within the effective bandwidth of the transducer and associated electrical circuit contribute to the response. The dependence of the response on the bandwidth, pulse duration time, pulse repetition rate and the frequency of the carrier wave has been studied.The nature of the evaluated responses are found to agree well with those observed in standard ultrasonic experiments e.g., the pulse-echo and pulse-superposition methods.
Frequency Domain Analysis of Photon Migration Based on the Microscopic Beer-Lambert Law
Authors: Yutaka Tsuchiya Yutaka Tsuchiya , Tsuneyuki Urakami Tsuneyuki Urakami
Published: October 2002

Exact analytic solutions for frequency domain responses of photon migration in variously shaped turbid media are derived based on a model in which the microscopic Beer-Lambert law holds. We show that the system function specified by the Fourier transform of the impulse response is a regular function, and that the temporal or spatial changes in the macroscopic absorption coefficient and the concentration of the absorber can therefore be determined from macroscopic observables such as amplitude, phase and modulation frequency of the probe light. The feasibility of using this technique in spectroscopy to determine the absolute concentration of an absorber in turbid media is also discussed. The advantage of these methods is that we do not need to take the boundary conditions into account. Similar approaches may also yield simple techniques to determine physical properties in various scientific fields.
Three-Dimensional Analysis of a Thermal Dissipation System with a Rectangular Diamond Heat Spreader on a Semi-infinite Copper Heat Sink
Authors: Ping Hui Ping Hui , Hong Siang Tan Hong Siang Tan
Published: October 2002

We consider the 3-D problem of conductive heat dissipation from a rectangular patch source of constant heat flux, through a finite rectangular parallelepiped heat spreader into a semi-infinite heat sink. Using the Fourier analysis, we have developed a rigorous series solution to this 3-D boundary value problem. Considering the case of a diamond heat spreader with a copper heat sink, we have investigated the effects of the geometrical dimensions of the spreader and the shape of the rectangular heat patch source on the thermal behavior of the system. The main results we have obtained are: (1) the commonly-used assumption of isothermal spreader-sink interface is valid provided that the spreader thickness is relatively large compared with the heating-patch's length and width; (2) for a square heat spreader with a fixed area ratio of rectangular heat patch to the spreader's cross section, the maximum temperature occurs for square heat patches as a result of the minimum perimeter; (3) for the same thickness and cross-section area of the spreaders, circular systems can be used to predict an upper bound of thermal behaviors for the rectangular heat dissipation systems.
International Standard of 90 mm Optical Disk (Magneto-Optical Media and Phase-Change Media)
Authors: Toshima Kunimaro Tanaka
Published: October 2002

Large-capacity, high-speed removable memory can provide portability of information and working environment. The ISO/IEC committee has started work on establishing enlarged-capacity standards for magneto-optical disks and phase-change disks. Both have direct overwriting function. This paper explains present technological status and future standardization plans.
Dynamic Analysis of a Gyrocompass
Authors: Ge Zheng-Ming , Yuan-Ching Lue Yuan-Ching Lue , Fu-Neng Ku Fu-Neng Ku
Published: October 2002

After giving the mathematical relation of the offset angle connection between the inner ring and the ballistic, and the mathematical model of the follow-up subsystem, the exact governing equations of gyrocompass with ballistic are given by Lagrange's equations. The explanation of the asymptotical stability about the system equilibrium by Arnold (1961) is shown to be wrong. Then use Liapunov theorem and Mukherjee-Chen theorem (1993) of direct method, Routh-Hurwitz criterion and multiple scales method are applied to study the stability about the equilibrium of the system in some cases.
Preparation and Electrical Properties of SrTiO3 Thin Films Deposited by Liquid Source Metal-Organic Chemical Vapor Deposition (MOCVD)
Authors: Kang Chang Seok , Hwang Cheol Seong , Cho Hag-Ju , Lee Byoung Taek , Park Soon Oh , Kim Jin Won , Horii Hideki , Lee Sang In , Young Bum Koh Young Bum Koh , Moon Yong Lee Moon Yong Lee
Published: October 2002

SrTiO3 thin films with thicknesses ranging from 30 nm to 60 nm were grown on
6-inch-diameter, platinized Si wafers by liquid source metal-organic chemical vapor
deposition (MOCVD). The crystalline quality and cation concentrations of the films
are strongly dependent on the deposition temperature with optimum temperatures
ranging from 500° C to 550° C. Semi-conformal deposition on submicron-sized storage
node patterns is obtained but further improvements in conformality and reproducibility
are required. The dielectric constant is about 210 irrespective of the film thickness
and leakage current densities are sufficiently small for the dynamic random access
memory (DRAM) applications. SiO2 equivalent thickness (T
ox) of the 30-nm-thick STO
film is 0.51 nm. The finding that the leakage current density and dielectric constant
are independent of the film thickness can be explained by a fully depleted model of
the STO film.
“PD” (Powerfull Optical Disk System) for Multimedia
Authors: Imanaka Ryoichi , Okazaki Yukinori , Saimi Tetsuo , Kawamura Ichiro , Ohta Takeo , Nishino Seiji
Published: October 2002

The use of CD-ROM has become widespread. PC users have generally been satisfied with the performance CD-ROM's, however, there is also a demand for larger-capacity removable rewritable media for “Multimedia” applications. The “PD” system offers users an optical disk which is easily handled such as floppy disks presently in use. In addition, “PD” can also read CD-ROM at fourtimes of the speed using a single common slot for both CD-ROM and PD media. The PD system (name of the new optical disk system prososed by Matsushita Electric Industrial. Co., Ltd.) has good compatibility for pit and groove recording. We calculated the reflectivity, tracking error, and ROM modulation, and varied the groove depth and width to maximize performance. A signal was written on various pregroove depths, and the reproduced signal ratio was measured. We obtained good results by using a phase-change material with the PD optical disk.
Dependence of Crystalline Structure and Lattice Parameters on Film Thickness in PbTiO3/Pt/MgO Epitaxial Structure
Authors: Fujisawa Hironori , Shimizu Masaru , Horiuchi Toshihisa , Shiosaki Tadashi , Matsushige Kazumi
Published: October 2002

In PbTiO3 (2.2–398 nm in thickness)/Pt/MgO(100) structure, the
dependence of the crystalline structure and lattice parameters of
PbTiO3 thin films on the film thickness was investigated using
the θ-2θ XRD method and the energy dispersive typed total
reflection X-ray diffraction method (ED-TXRD). By using the ED-TXRD
method, we can easily evaluate the in-plane structure of
island-structured PbTiO3 films at the initial growth stage.
Although the PbTiO3 thin films were highly c-axis orientated, the
formation of some a-domains was observed with increasing
thickness. The lattice parameters of the vertical dimension were
dependent on the film thickness, unlike those in-plane. From
these experimental results, the inner strain occurring in PbTiO3
thin films is discussed.