bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility Study of High Density Land/Groove Recording on Magnetooptical Disks
Authors: Narita Kyuya , Toshifumi Kawano Toshifumi Kawano , Hideharu Takeshima Hideharu Takeshima
Published: October 2002

Land/groove recording on a magnetooptical disk with polyolefin and polycarbonate substrates was demonstrated. The laser wavelength, numerical aperture of the objective lens and focused beam spot size were 680 nm, 0.55 and 1.15 µm, respectively. With a groove pitch of 1.3 µm, a carrier-to-noise ratio (CNR) of more than 45 dB with 0.6 µm mark length and crosstalk of less than -30 dB with 2.4 µm mark length were obtained. The effect of crosstalk cancellation in the polymer substrates was confirmed. Decreasing the vertical birefringence of the substrate improved the jitter and the CNR. The crosserase margin was 0.8 mW. It was identified that the CNR declined with the CNR phase shift.
Structure of Dusty Plasma in External Fields: Simulation and Theory
Authors: Hiroo Totsuji Hiroo Totsuji , Tokunari Kishimoto Tokunari Kishimoto , Chieko Totsuji Chieko Totsuji
Published: October 2002

To investigate various structures experimentally observed in dusty plasmas, a Yukawa system in a one-dimensional external field is simulated by molecular dynamics with deformable periodic boundary conditions and constant volume and temperature. At low temperatures, particles are organized into thin layers (sheets) and the number of layers (sheets) changes with the parameters, the whole system being rearranged from nearly equipartitioned layers to other nearly equipartitioned layers. The shell (sheet) model, which has been successful for confined one-component plasmas, is extended to this system and the results of numerical simulations are reproduced accurately. The effect of the cohesive energy in each layer is of essential importance to reproduce discrete changes in the number of sheets.
Reactive Ion Etching Mechanism of Copper Film in Chlorine-based Electron Cyclotron Resonance Plasma
Authors: Sung-Kwon Lee Sung-Kwon Lee , Sung-Soon Chun Sung-Soon Chun , ChanYong Hwang ChanYong Hwang , Won-Jong Lee Won-Jong Lee
Published: October 2002

In order to investigate the reactive ion etching mechanism of the copper films in CCl4/N2 electron cyclotron resonance (ECR) plasma, the dependences of the copper etch rate on various etching parameters, the etch products as well as their depth distributions and the concentration of chlorine radicals in the plasma were examined. It was found that the etching species in CCl4 plasma is not CCl

x

but atomic chlorine (Cl) and the etch product formed at the surface of the copper film is not CuCl but CuCl2. In order to carry out reactive ion etching of copper film in chlorine-based plasma the substrate temperature should be above 210° C, below which the etch product has too low vapor pressure to be volatile. At the substrate temperature above 210° C, the copper etch rate is not limited by the removal rate of the etch product but limited by its formation rate which depends on the concentration of chlorine radicals and the reaction rate between the etching species and the copper film. The etch rate is also increased by applying a negative bias to the substrate, the role of which is the enhancement of the formation rate of the etch product by activating chemical reactions due to energetic ion bombardment. Adding small amounts of CF4 to CCl4 plasma increases the etch rate dependence on ion bombardment energy by forming involatile copper fluoride on the etched surface.
Selective Growth Conditions of ZnSe/ZnS Heterostructures on (001) GaAs with Metalorganic Molecular Beam Epitaxy
Authors: Akio Ueta Akio Ueta , Ikuo Suemune Ikuo Suemune , Katsuhiro Uesugi Katsuhiro Uesugi , Munetaka Arita Munetaka Arita , Adrian Avramescu Adrian Avramescu , Takahiro Numai Takahiro Numai , Hideaki Machida Hideaki Machida , Norio Shimoyama Norio Shimoyama
Published: October 2002

Selective growth of ZnSe and ZnS on (001) GaAs substrates partially covered with SiO
x
was examined by metalorganic molecular-beam epitaxy. The growth temperature was the key factor for the selective growth, and the minimum growth temperature of ZnS to achieve selective growth was 450°C. On the other hand, the minimum growth temperature of ZnSe was 500°C. This difference of temperature for the selective growth made it difficult to grow high-quality ZnSe/ZnS heterostructures. To overcome this problem, we used periodic supply epitaxy to lower the selective growth temperature of ZnSe. Supply interruption after short time supply of ZnSe enhances the desorption of precursors especially on SiO
x
surfaces and this suppresses the nucleation of ZnSe on SiO
x
surfaces. The lower VI/II ratio also suppresses nucleation of ZnSe on SiO
x
. The selective growth of ZnSe was thus achieved at 430°C with a VI/II ratio of 1. The minimum selective growth temperature reported on ZnSe up to now is 600°C, and this work demonstrated the selective growth of ZnSe at a considerably lower temperature. We have prepared a ZnSe/ZnS single quantum well (SQW) at 450°C under the selective growth condition and the bright band edge emission from the ZnSe well was observed by photoluminescence measurement at 13 K.
Methods of Improving the Efficiency of Thermoelectric Energy Conversion and Characteristic Energy Range of Carriers
Authors: Yoshimasa Nishio Yoshimasa Nishio , Tohru Hirano Tohru Hirano
Published: October 2002

We discuss how strongly the thermoelectric figure of merit Z is influenced by carriers in a particular energy range. From the knowledge of the energy dependence of the functional derivative of Z with respect to differential conductivity, it is shown that the carriers in the low and high energy range have a harmful effect on Z, while those in the middle energy range have a favorable effect on Z. This result enables one to understand the various methods of improving the efficiency of thermoelectric energy conversion from a unified point of view.
Phase Diagrams in Successive Phase Transitions in Ferroelectrics with Perovskite-type Structure: Cases of the First Order Transitions from the Cubic Phase
Authors: Ishibashi Kazuhiko Fujita
Published: October 2002

Phase diagrams possible in successive phase transitions of BaTiO3-type oxides are discussed within the framework of the Landau theory for cases where the transition from the cubic phase is of the first order. Various critical points may appear when the model parameters change.
New Method for Fabricating a Mixed Monolayer Using Self-assembly of Trichlorosilanes and Mapping of Different Molecules in the Mixed Monolayer Using a Frictional Force Microscopy with a Tip Chemically Modified with Fluoroalkyltrichlorosilanes for Chemical Sensing
Authors: Tohru Nakagawa Tohru Nakagawa , Mamoru Soga Mamoru Soga
Published: October 2002

An alkyltrichlorosilane/fluoroalkyltrichlorosilane mixed monolayer was fabricated by the self-assembly of an octadecyltrichlorosilane (OTS) monolayer having pinholes with 10–200 nm radii and following adsorption of (2-(perfluorooctyl)ethyl)trichlorosilane (FS-17) into the pinholes. The adsorption of FS-17 into the pinholes was confirmed using an atomic force microscope (AFM) by measuring the hole depths in the OTS monolayer, which decreased by a molecular length of FS-17 after the adsorption of the FS-17. The OTS and FS-17 molecules in the mixed monolayer were mapped using a frictional force microscope (FFM) whose tip was chemically modified with FS-17 molecules. In the case of the conventional observation using a FFM whose tip is not chemically modified, the frictional forces of the tip on the FS-17 molecules in the pinholes were smaller than those on the OTS monolayer. In contrast, the frictional forces of the chemically modified tip on FS-17 molecules in the pinholes were larger than those on the OTS monolayer. These results indicate that the FS-17 molecules on the tip have a critical influence on the frictional force between the tip and the molecules, and that the chemically modified tip may be used for discriminating different chemical groups in the monolayer. We propose that our new techniques for fabricating and estimating molecular distributions of the mixed monolayer will be useful in the development of molecular electronic devices.
Radiative Electron Capture in 55Fe
Authors: Abdelhady Yousef Abdelhady Yousef , Mamdouh Abdelrahman Mamdouh Abdelrahman , Nader Hasan Nader Hasan
Published: October 2002

The internal bremsstrahlung (IB) spectra accompanying electron capture in 55Fe, has been investigated with particular emphasis on the low energy region using a NaI (Tl) scintillation spectrometer. Corrections for background and absorption are carried out. A set of corrections such as crystal detection efficiency, resolution, geometrical factor, the ratio of photoelectric to total cross-section, photon backscattering and iodine X-ray escape are made by constructing a response matrix (46 energy bins and 140 channels) of the detector assembly for the experimental condition used. Using this matrix, the true IB energy spectrum is obtained by iterative unfolding the pulse-height distribution for comparison with the theoretical spectra. In addition, the response matrix is used directly to fold the theoretical probabilities for comparison with the experimental pulse-height distribution. It is found that the intensity of the extremely low energy photons is much greater than that estimated from Morrison and Shiff's theory. Agreement is best between the experimental observation and the theory of Martin and Glauber, where the p-electron capture and the Coulomb effect are taken into consideration.
Kinetics of Radicals in CF 4 and C 4F 8 Electron Cyclotron Resonance Plasmas
Authors: Koji Miyata Koji Miyata , Masaru Hori Masaru Hori , Toshio Goto Toshio Goto
Published: October 2002

Temporal variations in densities of CF and CF2 radicals were measured at rising phases of plasma ignition in CF4 and C4F8 electron-cyclotron-resonance (ECR) plasmas by infrared diode laser absorption spectroscopy. It was found that CF2 radical densities at the rising phase briefly became larger than those at the steady state in the C4F8 plasma. This finding shows that the CF2 is generated in abundance by the rapid dissociation of C4F8 molecules at the discharge ignition. The variations of CF2 and CF radical densities were demonstrated using a computer calculation to characterize the chemistry in the CF4 and C4F8 plasmas numerically. Chemical models in the CF4 and C4F8 ECR plasmas were presented based on the results obtained by the experiment and calculation. The models suggested that the higher fluorocarbons, that is CXFY (X ≥2), were important in the C4F8 plasma as dissociation paths from C4F8 molecules to CFX (X=1–3) radicals and as polymer precursors.
Stability and Chaotic Dynamics of a Rate Gyro with Feedback Control
Authors: Zheng-Ming Ge Zheng-Ming Ge , Heng-Hui Chen Heng-Hui Chen
Published: October 2002

An analysis is presented of a single-axis rate gyro subjected to linear feedback control mounted on a space vehicle that is spinning with uncertain angular velocity ω
Z
(t) about its spin of the gyro. The stability of the nonlinear nonautonomous system is investigated by Liapunov stability and instability theorems. As the electrical time constant is much smaller than the mechanical time constant, the full singularly perturbed system is obtained. We study the stability of the system by forming a Liapunov function candidate as a linear combination of the Liapunov functions for the reduced and boundary-layer systems. When the perturbation near angular velocity ω
Z
(t) of the space vehicle is harmonic, the feedback control system reduces to a planar system of parametrical excitation by the singular perturbation theory. Using the Melnikov technique, we can give criteria for the existence of chaos in the gyro motion. The numerical results, in which the existence of chaos is demonstrated, are presented in the form of phase plane, Poincaré maps, bifurcation diagrams and Lyapunov exponents.
ESR Study of Glass Transition in Mn-Doped Se70Te30 Chalcogenide Glass in Non-Isothermal Process
Authors: Chakraborty Tapan Kumar , Ueda Shoichi , Akio Kitagawa Akio Kitagawa , Masakuni Suzuki Masakuni Suzuki
Published: October 2002

The ESR measurements of manganese ions in Se70Te30 chalcogenide glass have been carried out during rate-scan heating in order to investigate the glass transition phenomena. ESR signals observed at various measuring temperatures during rate-scan heating are centered at g=2.00 with no hyperfine structure. No remarkable change in the peak-to-peak linewidth occurs from room temperature up to the glass transition temperature, but the linewidth begins to decrease around the glass transition temperature and to increase above the crystallization temperature. When the maximum temperature in the rate-scan heating is above the glass transition but below the crystallization temperature, the ESR linewidth retraces almost the same curve in the cooling to room temperature. This line narrowing above the glass transition temperature may be regarded as motional narrowing occurring in the supercooled liquid state.
Two Dimensional Stochastic Monte Carlo Simulation for Smoothing of Scratched Surface of Aluminum Thin Film at 773 K
Authors: Okude Shin'ichiro , Ochiai Kunie , Kuwabara Manabu , Hasunuma Masahiko , Kawakubo Takashi
Published: October 2002

In the simulation, deep (0.56 eV) interatomic potential (IAP) based on the heat of evaporation, and shallow (0.12 eV) IAP based on the activation energy of surface migration were tested. As the initial condition, rectangle grooves were scratched on a film surface before smoothing. When the deep IAP was used, artificial and unacceptable stable facets appeared during the simulation, and the surface smoothing process was interrupted. When the shallow IAP was used and the aspect ratio (AR) of the initial surface groove was set at 1.0, the evolution of the surface profile (EOSP) was consistent with that calculated by an analytical diffusion equation. When the initial AR was changed to 2.0, the EOSP became irregular, which agreed with our expectation. The effect of the size of the surface groove was discussed. A comment on the relationship between the present smoothing process and the reflow process, which may be suitable for the formation of interconnections in LSI, is given.
Measurement of the Breakdown Voltage of Lateral Power Metal-Oxide-Semiconductor Field-Effect-Transistors on a Silicon-on-Insulator Film with Varying the Surface Design around the Gate Region
Authors: Hitoshi Sumida Hitoshi Sumida , Atsuo Hirabayashi Atsuo Hirabayashi
Published: October 2002

The gate structure dependence of the blocking capability of lateral power metal-oxide-semiconductor field-effect-transistors (MOSFETs) on a silicon-on-insulator (SOI) film is investigated. Experimental results of the breakdown voltage with varying the gate electrode and gate oxide lengths are presented, and are compared with those of the devices fabricated on a n-type substrate. The breakdown voltage of the SOI devices is insensitive to the surface design around the gate structure, which is quite different from that of the devices on the n-type substrate.
Second-Order Optical Nonlinearity of Urethane-Urea Copolymers: Influence of Main-Chain Structure
Authors: Tsuchimori Masaaki , Watanabe Osamu , Shin-ichi Ogata Shin-ichi Ogata , Akane Okada Akane Okada
Published: October 2002

Urethane-urea copolymers with different main-chain structures have been synthesized, and their nonlinear optical (NLO) properties compared. The glass transition temperatures (T
g) depended on their main-chain structures. The optimum poling temperature of each copolymer was 45° C higher than its T
g, indicating the existence of forces preventing the disordering of poled NLO groups. The observed temporal behavior of d
33 at 100° C indicates that introducing urea groups into a polyurethane main chain can increase the temporal stability of the polyurethane without improving the stiffness of the main chain.
Study on Electronic Structure and Optoelectronic Properties of Indium Oxide by First-Principles Calculations
Authors: Odaka Hidefumi , Iwata Shuichi , Taga Naoaki , Ohnishi Shuhei , Kaneta Yasunori , Shigesato Yuzo
Published: October 2002

The electronic structure of In2O3has been studied for the first time using a first-principles calculation method based on the density functional theory. Although the complexity of the crystal structure of In2O3which contained 40 atoms in its unit cell had prevented studies of its electronic structure, we were able to study it using the characteristic of minimum basis sets of the linear muffin-tin orbital method with atomic sphere approximation. The calculated partial density of states (PDOS) showed that the valence bands were composed mainly of oxygen 2p-like states and the conduction bands consisted mainly of indium 5s-like states with free-electron-like character. The results of PDOS analysis were used to analyze the spectra from X-ray photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy. Calculated results were also used to interpret optoelectronic properties of tin-doped indium oxide.
X-Ray Absorption Spectroscopic Studies on Layered FeWO 4Cl and Its Lithium Intercalate
Authors: Choy Jin-Ho , Yoon Joo-Byoung , Park Nam-Gyu , Young-Il Kim Young-Il Kim , Kyoo-Seung Han Kyoo-Seung Han
Published: October 2002

Lithium intercalation into FeWO4Cl leads to the structural phase transformation from tetragonal to monoclinic. According to Fe K-edge X-ray absorption near edge structure (XANES) spectroscopic analysis, only the Fe3+ ion in the FeWO4Cl lattice is reduced to Fe2+ with an increment of site symmetry from C
4v
to O
h upon lithium intercalation. On the other hand, the white line intensity at the W L-edge XANES becomes slightly enhanced after intercalation, indicating an increase of the (W6+–O) bond covalency due to a decrease of the competing (Fe2+–O) bond strength. W L3-edge extended X-ray absorption fine structure (EXAFS) analyses for FeWO4Cl and LiFeWO4Cl show that the regular tetrahedron of the WO4
2- group in FeWO4Cl becomes distorted upon lithium intercalation.
Curious Structural Characteristics from the Carbon Deposits on the Graphitic Electrodes Subjected to Arc Evaporation
Authors: Kamalakaran Radha , Ajay Kumar Singh Ajay Kumar Singh , Onkar Nath Srivastava Onkar Nath Srivastava
Published: October 2002

We report the transmission electron microscopic investigations made on the tips of the graphite electrodes used for production of C60-buckminsterfullerene. This was achieved by triggering an electrical arc (150 A, 20 V, ac) in helium (100 Torr) atmosphere between the graphite electrodes and then scraping the tip of the electrode to prepare sample for electron microscopy. The scraped material was investigated in the CM-12 Philips transmission electron microscope both in diffraction and imaging modes. An abundance of tubules were found and the diffraction patterns from them exhibited sharp diffraction spots arranged along elliptical rings. On tilting the specimen the major axis of the ellipse varied in definite was depending on the relative orientations of electron beam, tubule axis and tilt axis. A detailed geometrical exemplification has been proposed which explains the observed features in the diffraction patterns. The occurrence of possibly a new form of carbon corresponding to primitive cubic with a=2.14 Å and nucleation of diamond on ac electrical arc treated graphite electrode are also mentioned.
Real-Time Staging in Optical Disk Library
Authors: Mizukami Makoto , Shigetaro Iwatsu Shigetaro Iwatsu , Nobuyoshi Izawa Nobuyoshi Izawa
Published: October 2002

A new real-time staging technique in which disks are rated according to the likelihood of use, even with respect to storage location, is explained. In this technique, the exchange algorithm for the disks in a storehouse is simplified by disk management in groups; i.e., disks are exchanged between groups according to likelihood of use. Here, if a storehouse in an optical disk library is divided into N groups, real-time staging can reduce the total travel length of a robotic hand to as little as 1/N of the conventional method. Moreover, if the prefetch and postrestore processes are also used to speed up the disk exchange operation at the disk drive, the total travel length is similarly shortened to 2/3N of the conventional method, and the total travel time to 1/3.
SiNx :H/SiO2 Double-Layer Passivation With Hydrogen-Radical Annealing For Solar Cells
Authors: Nagayoshi Hiroshi , Ikeda Makoto , Yamaguchi Misako , Uematsu Tsuyoshi , Tadashi Saitoh Tadashi Saitoh , Koichi Kamisako Koichi Kamisako
Published: October 2002

A SiN

x

:H/SiO2 double-layer structure as the passivation layer and hydrogen-radical post annealing were introduced to decrease the surface recombination velocity on crystalline silicon. Effective lifetime was much increased by introducing a SiN

x

:H/SiO2 double-layer passivation structure instead of a SiN

x

:H or SiO2 single-layer, while the hydrogen radical post annealing improves the interface characteristics more effectively than N2 annealing. The results of C–V measurement suggest that many positive charges exist in the SiN

x

:H layer. The combination of field effect by these charges and the decrease of SiO2/c-Si interface defects by hydrogen-radical annealing effectively decrease the surface recombination velocity.
Numerical Study of Nonuniform Energy Deposition and Flowfield in Discharge-Pumped XeCl Excimer Laser
Authors: Zhu Qifeng , Imada Go , Masuda Wataru , Yatsui Kiyoshi
Published: October 2002

Inhomogeneous energy deposition in a discharge-pumped excimer laser rapidly heats the gas, resulting in a nonuniform distribution of the gas temperature. Shock waves and nonuniform flowfields generated by the relaxation of the heated gas can induce discharge instabilities and limit the repetition rate of the laser. The gas temperature profile, which is necessary for the numerical study of the shock waves and flowfields, is calculated using a self-consistent discharge model. The computational results show that the temperature profile is sensitive to the electric field distribution and gas mixture. The temperature profile tends to be steeper when the nonuniformity in the electric field increases and the xenon concentration increases. Furthermore, the shock waves and unsteady flowfields are studied using two-dimensional compressible gas dynamic equations and the total variation diminishing (TVD) numerical scheme. Finally, an analysis using a blast wave model shows that the shock waves from preionization pin arrays decay rapidly.
Low-Energy Electron Transmission Spectroscopy of Thin Films of Chloroaluminum Phthalocyanine on MoS2
Authors: Ueno Nobuo , Azuma Yasushi , Yokota Takayuki , Aoki Masaru , Koji K. Okudaira Koji K. Okudaira , Yoshiya Harada Yoshiya Harada
Published: October 2002

The growth of chloroaluminum phthalocyanine (ClAlPc) thin films on MoS2 surfaces was studied by low-energy electron transmission (LEET) spectroscopy. We observed that the as-grown monolayer, prepared by vacuum deposition, consists of islands of ClAlPc multilayers and the molecules spread over the substrate surface to form a uniform monolayer by heat treatment. Furthermore, we found that for heat-treated films the vacuum level of the sample system oscillates with increasing the film thickness from 0 to 2 monolayers. For the monolayer, the change of the vacuum level with respect to the substrate Δφ (=φ film-φ substrate) was positive, while for the doublelayer it was negative. These results indicate that in the monolayer the molecules lie flat with the Cl atoms protruding outside the film to form an electric dipole layer directing to the substrate, and in the doublelayer the molecules in the outer layer are turned over with the Cl atoms protruding inside the film to compensate the dipole originating from the first monolayer. Furthermore the thickness independent characteristics of LEET spectra above the doublelayer suggest that thicker films consist of a stack of a double layer-like structures.
Determination of the Mass Resolution and the Depth Resolution of Time of Flight Elastic Recoil Detection Analysis Using Heavy Ion Beams
Authors: Hong Wan , Hayakawa Shinjiro , Maeda Kuniko , Fukuda Shigekazu , Yanokura Minoru , Aratani Michi , Kimura Kazuie , Tanihata Yohichi Gohshi
Published: October 2002

The mass resolution and the depth resolution of the time of flight elastic recoil detection analysis (TOF-ERDA) system for a Si wafer sample have been determined using 20Ne, 40Ar and 136Xe ions as probes. The incident energies were 20.0 MeV for Ne, 41.5 MeV and 22.6 MeV for Ar and 138.1 MeV for Xe, respectively. The mass resolutions of Si were found to be from 1.90 au for 41.5 MeV Ar to 3.32 for 22.6 MeV Ar. Also, the depth resolutions were determined from 1.67×1017 atoms/cm2 for 20.0 MeV Ne to 2.67×1017 atoms/cm2 for 138.1 MeV Xe near to the sample surface. The advantages of each probe ion were compared. A superconductor sample, YBa2Cu3O7-
x

, was measured using Ar accelerated to 41.5 MeV; Y, Ba, Cu and O were clearly separated.
Optical pH Sensing Properties of Coumarin-4-Doped Sol–Gel Coating Film
Authors: Takahashi Yoshihiro , Takeda Takayuki , Suzuki Kazuyuki , Maeda Akinori , Kojima Kenzo , Ohta Hiroshi
Published: October 2002

Immobilized coumarin-4 coating film prepared by the sol–gel process was used as an optic pH sensing probe. The coumarin dye shows emission bands around 430 and 395 nm appearing in the acid-base reaction of coumarin 4. The probe response relies on the change of the fluorescence intensity ratio under emission bands at 430 and 395 nm. That stability is examined and related with the preparation conditions of the sol–gel coating films.
Energy-Dispersive Grazing Incidence Diffraction with Synchrotron Radiation White X-Rays of Very Thin Polycrystalline Silicon Films
Authors: Akimoto Akio Tanikawa
Published: October 2002

The precise alignment of the substrate-orientation in an energy-dispersive grazing incidence diffraction measurement with synchrotron-radiation white X-rays is used in the analysis of orientations of 50- to 10000-Å-thick low-pressure chemical-vapor deposited polycrystalline Si films on amorphous SiO2 layers. The results reveal characteristic growth modes where the preferred orientation of grains is suppressed in the thickness range from 100 to 1000 Å, and where the orientation is determined by the effect of the initial island growth mode (i.e., the Volmer-Weber mode) when the thickness is less than 100 Å.
The Removal of Intentionally Contaminated Cu Impurities on Si Substrate Using Remote H-plasma Treatments
Authors: Ahn Taehang , Park Myounggu , Lee Chongmu , Jong-Wan Park Jong-Wan Park , Hyeongtag Jeon Hyeongtag Jeon
Published: October 2002

The removal of Cu impurities on Si substrate was investigated by using remote H-plasma treatments. This work focussed on eliminating Cu impurities on Si substrate which was intentionally contaminated by dipping it into 1 ppm CuCl2 chemical standard solution. Remote H-plasma treatments were conducted to remove Cu impurities and depended on the plasma exposure times and distances. After the remote H-plasma treatments, Si surfaces were analyzed by TXRF (total reflection X-ray fluorescence) and AFM (atomic force microscope). The Cu concentration was reduced more than a factor of 10–100 and its surface roughness improved significantly after the remote H-plasma treatments. Cu2+ ions can be reduced in the form of Cu element and formed as the compound ( Cu(OH)2) and the chemical oxides (SiO and SiO2) on the Si substrate. Under the condition of remote H-plasma, the removal mechanism of Cu impurities is studied and understood by applying the formation mechanism of volatile by-products such as CuH

x

*, CuO*, SiO* and H2O*, and the lift-off phenomena during the removal of underlying oxides such as SiO and SiO2.
High Sensitive Capillary Wave Method for the Determination of Detergents in Water
Authors: Berezina Sofia , Juraj Slabeycius Juraj Slabeycius , Pavol Koštial Pavol Koštial
Published: October 2002

A detection method of detergent presence in water, based on the capillary waves propagation on the water surface has been developed. The efficiency of the method was tested on a water solution of a commercially produced detergent. The sensitivity of the developed method was tested in the concentration span from 1×10-6 up to 170×10-6. The good repetition ability and agreement with the theory prediction was achieved.
Step Coverage Characteristics of Pb(Zr, Ti)O3 Thin Films on Various Electrode Materials by Metalorganic Chemical Vapor Deposition
Authors: Shimizu Masaru , Hyodo Satoshi , Fujisawa Hironori , Shiosaki Hirohiko Niu
Published: October 2002

The step coverage characteristics of Pb(Zr, Ti)O3 (PZT) thin films on steps
with various electrode materials, such as Pt/SiO2, Ir/SiO2 and IrO2/SiO2, by
metalorganic chemical vapor deposition (MOCVD) were investigated. The
step coverage of PZT films deposited on Pt/SiO2 at 500 and 550° C was
80–87%. Deformation of Pt/SiO2 steps was observed when PZT films were
deposited at 600° C. The cause of this deformation of steps was mainly the
diffusion of Pb into the steps. When PZT thin films were deposited on
Ir/SiO2 at 500–600° C and IrO2/SiO2
at 500 and 550° C, good step coverage of
76–93% and 70–85% was obtained, respectively.
Preparation and Characterization of Epitaxial Lead Zirconate Titanate Films on Pt/MgO Substrates by Metalorganic Chemical Vapor Deposition
Authors: Sakurai Atsushi , Shiratsuyu Kohsuke , Hiroshi Takagi Hiroshi Takagi , Yukio Sakabe Yukio Sakabe
Published: October 2002

Lead zirconate titanate (PZT) films were prepared on Pt(100)/MgO(100) substrates by
metalorganic chemical vapor deposition. By optimizing the deposition conditions, c-axis
oriented PZT epitaxial films were obtained. The epitaxial PZT films deposited on
Pt/MgO substrates exhibited dielectric constants as high as 425, remanent polarization of
50 µC/cm2, a coercive field of 33 kV/cm a leakage-current smaller than 10-6 A/cm2 at the
electric field lower than 200 kV/cm.
Preparation and Properties of (Pb, Ca)TiO3 Thin Films by Multiple-Cathode Sputtering
Authors: Ichinose Hiroshi Maiwa
Published: October 2002

(Pb, Ca)TiO3 (PCT) thin films were fabricated by multiple-cathode RF-magnetron sputtering,
using PbO, CaTiO3 and Ti metal targets. PCT films deposited on Pt/Ti/SiO2/Si and Pt/MgO at
the substrate temperature from 460° C to 540° C had perovskite structures. The relationship
between the substrate temperature and the film properties were investigated. The remanent
polarization, dielectric constant and leakage current of the 200-nm-thick PCT(Ca/Ti=0.30) thin
films deposited on Pt/Ti/SiO2/Si at 460° C and on Pt/MgO at 500° C were 22.5 µ C/cm2 225 and
on the order of 10-7 A/cm2 (at a field of 250 kV/cm), 41 µ C/cm2, 174 and on the order of
10-7 A/cm2 (at a field of 250 kV/cm), respectively.
Microstructure and Preferred Orientation of BaTiO3 Thin Films on Pt/Ti/SiO2/substrates Prepared by Ultrasonic Spraying Deposition
Authors: Kim In-Tae , Su Jin Chung Su Jin Chung , Soon Ja Park Soon Ja Park
Published: October 2002

BaTiO3 thin films were fabricated on Pt/Ti/SiO2/Si substrates by ultrasonic
spraying deposition. Thin films had different preferred orientations and
microstructures for varying substrate temperatures and solution concentrations.
This was caused by the different deposition behavior, whether it was deposited
as large molecules or clusters. At low temperatures the surface migration was
restricted due to low mobility, therefore, the films were composed of very small
grains which had an energetically favored growing plane or random orientation.
At sufficiently high temperatures, direct nucleation of BaTiO3 on Pt occurred due
to the lattice matching with the substrate and high surface mobility. The change
of microstructures could be explained by grain growth and surface mobility. The
preferred orientation was enhanced by the increase in the growth rate due to
the increasing supply of sources when the concentration of solution increased.
However, the microstructures of thin films were not affected by solution concentrations.
Variation of Electrical Conduction Phenomena of Pt/ (Ba, Sr)TiO3/Pt Capacitors by Different Top Electrode Formation Processes
Authors: Lee Ki Hoon , Hwang Cheol Seong , Lee Byoung Taek , Kim Wan don , Horii Hideki , Kang Chang Seok , Cho Hag-Ju , Sang In Lee Sang In Lee , Moon Young Lee Moon Young Lee
Published: October 2002

Electrical conduction behaviors of Pt/ (Ba, Sr)TiO3/Pt thin film capacitors having top Pt
electrodes with different deposition powers are investigated. The capacitors having top Pt
electrode with deposition power of 0.2 kW show Schottky emission behavior at both top and
bottom electrode interfaces with potential barrier heights of 1.24–1.48 eV and 1.88–2.08 eV,
respectively. However, the capacitor having top Pt electrode with larger deposition power of
0.5 kW shows Schottky emission behavior only at bottom electrode interface with barrier of
1.61–1.89 eV. Interface with top electrode appears to have very low resistance, and a positive
temperature coefficient of resistivity (PTCR) effect is observed when the electrons are
injected from the top electrode to bottom electrode through BST film. Top Pt electrode
becomes very rough by grain growth during postannealing when the top Pt is deposited with
powers of larger than 0.5 kW. Roughening of the top Pt results in the low-resistance contact
behavior at the interface between top Pt and BST, which results in PTCR effect.
Electrical Properties of All-Perovskite Oxide (SrRuO3/BaxSr1-xTiO3/SrRuO3) Capacitors
Authors: Izuha Mitsuaki , Kazuhide Abe Kazuhide Abe , Noburu Fukushima Noburu Fukushima
Published: October 2002

Thin film capacitors consisting totally of perovskite oxides ( SrRuO3/Ba

x

Sr1-
x

TiO3 (20 nm) / SrRuO3)
were fabricated on Si and SrTiO3 substrates by rf magnetron
sputtering. The dielectric constants for polycrystalline and single-crystal epitaxial
films were observed to be 274 and 681, respectively. The lowest SiO2 equivalent
thickness for the single-crystal epitaxial capacitor was 0.11 nm. The leakage current
density was less than 1×10-7 A/cm2 for a bias of ±1.2 V. The electrical properties of
all-perovskite oxide capacitors were compared with those of samples with Pt top
electrodes, and large differences in the values of the dielectric constant were observed.
These are explained in terms of differences in the interface between the dielectric and
the top electrode and the possible existence of a low-ε layer at the interface between
the Pt top electrode and Ba

x

Sr1-
x

TiO3. In addition, the origin of the large difference
in the dielectric constants for polycrystalline and single-crystal epitaxial capacitors are
discussed in terms of the lattice distortion in Ba

x

Sr1-
x

TiO3.
Preparation and Properties of K(Sr0.75Ba0.25)2Nb5O15 Thin Films by Chemical Solution Deposition Method
Authors: Sakamoto Wataru , Kawase Akihiro , Toshinobu Yogo Toshinobu Yogo , Shin-ichi Hirano Shin-ichi Hirano
Published: October 2002

Crack-free K(Sr0.75Ba0.25)2Nb5O15 (KSBN75) thin films were successfully synthesized by the chemical solution deposition method. A homogeneous and stable precursor solution was prepared by controlling the
reaction of metallo-organics. KSBN75 precursor powders were directly
crystallized in the tetragonal tungsten bronze phase without formation
of a low-temperature phase above 650° C. KSBN75 thin films on
MgO(100) and Pt(100)/MgO(100) also crystallized in the tetragonal
tungsten bronze phase with preferred c-axis orientation at 700° C. Two
crystal lattice planes of KSBN75 were intergrown at an orientation of 18.5° on MgO(100) and Pt(100)/MgO(100) substrates. The Curie point
of KSBN75 thin film was around 70° C at 10 kHz. KSBN75 thin films on
Pt(100)/MgO(100) substrates exhibited typical P-E hysteresis.
Contactless Estimation of the Surface Recombination Velocity at High-Low Junction Surfaces Fabricated by the Ion-Implantation Technique
Authors: Makino Takanori , Ichimura Masaya , Yoshida Hideaki , Morita Etsuro , Akira Usami Akira Usami
Published: October 2002

Surface properties of ion-implanted silicon are investigated by the microwave photoconductivity decay method. The effective surface recombination velocity (S) is estimated by fitting of the experimental decay curve of excess carrier concentration with a theoretical decay curve. The results show that S is almost inversely proportional to the carrier concentration of the heavily doped layer formed by the ion-implantation for both types of high-low junction ( n+n, p+p). Thus the present method is a powerful tool for surface characterization.
Lead-Free Piezoelectric Ceramics of (Bi1/2Na1/2)TiO3–1/2(Bi2O3·Sc2O3) System
Authors: Hajime Nagata Hajime Nagata , Tadashi Takenaka Tadashi Takenaka
Published: October 2002

Bismuth sodium titanate, (Bi1/2Na1/2)TiO3 (BNT)-based solid solution,
(1- x)(Bi1/2Na1/2)TiO3– x1/2(Bi2O3·Sc2O3) [BNST-100 x], was studied in order to determine its dielectric,
ferroelectric and piezoelectric properties as a new group of lead-free piezoelectric ceramics.
Measurements of dielectric and piezoelectric properties show that the BNST-100 x ceramics
of composition near BNT composition have relatively low free permittivity, ε
33
T/ε
0 (=431)
and high electromechanical coupling factor, k
33 (=0.42). These ceramics are good candidates
for use as lead-free piezoelectric ceramics.
GHz-Band Surface Acoustic Wave Devices Using the Second Leaky Mode on LiTaO3 and LiNbO3
Authors: Kobayashi Yasumi , Tanaka Naoki , Baba Yoko , Okano Hiroshi , Usuki Tatsuro , Shimizu Kenichi Shibata
Published: October 2002

The propagation characteristics of a new high-phase-velocity leaky surface
acoustic wave (SAW) mode, which is called the second leaky mode, were analyzed
experimentally in a periodic structure on LiTaO3 (90°, 90°, 31°) and LiNbO3
(90°, 90°, 37°). As regards the mode on LiTaO3, the propagation loss is lowest when KH
( K=wave number, H=Al electrode thickness) is about 0.5. The higher mode of the
second leaky mode is excited when KH is more than 0.7. As regards the mode on
LiNbO3, the propagation loss exhibits no distinct minimum when plotted against KH.
The higher mode of the second leaky mode is excited when KH is more than 0.6. A
ladder-type band-pass SAW filter utilizing the second leaky mode on LiTaO3 was
designed and fabricated by applying the analysis extended results to the periodic
structure. The pitch of the electrode fingers is 0.8 µ m. The center frequency of the
pass band is 1.866 GHz. The minimum insertion loss is 3.3 dB. The width of the 1 dB
pass band is 32 MHz. The attenuation at a center frequency of ±60 MHz is 25 dB.
The measured characteristics of this filter are sufficient for practical mobile
communication systems.
Evaluation of the Reliability of Piezoelectric Ceramic Transformers
Authors: Nagata Kunihiro , Kato Jirawat Thongrueng
Published: October 2002

Piezoelectric ceramic transformers were prepared to evaluate their reliability as well as their practical applicability in
driving circuits. The driving circuit controlled an AC voltage of 20–250 V, and it also followed the resonant frequency of the
piezoelectric ceramic transformer. The output voltage of the piezoelectric ceramic transformer was dependent upon the mechanical
quality factors of the material. The generation of heat in the piezoelectric ceramic transformer is easy if the load resistance is
small. The lifetime of the piezoelectric ceramic transformer connected to a load resistance of 100 k Ω was longer than that connected to a load resistance of 10 k Ω.
Lattice Image Observations of Nanoscale Ordered Regions in Pb(Mg1/3Nb2/3)O3
Authors: Mishima Tsuneo , Fujioka Hiromi , Nagakari Shoken , Kosei Kamigaki Kosei Kamigaki , Shinji Nambu Shinji Nambu
Published: October 2002

The grain-size dependence of nanoscale ordered regions in Pb(Mg1/3Nb2/3)O3 (PMN) has been studied using
lattice images obtained by transmission electron microscopy. It was found that the size of nanoscale ordered regions, which is
strongly related to dielectric properties, depends on the grain size. The nanoscale ordered regions of fine-grained PMN with
average grain sizes of 0.32 and 0.15 µ m are clearly smaller than those of coarse-grained PMN with an average grain size
of 1.95 µ m. The dielectric constant is found to be markedly low with grain size below ∼0.3 µ m.
Thermodynamic Stability of the Spontaneous Polarization and the Space Charge Layer in Ferroelectric/Semiconductor Heterostructures
Authors: Yukio Watanabe Yukio Watanabe , Daisuke Sawamura Daisuke Sawamura
Published: October 2002

The feasibility of memory retention of ferroelectric field-effect devices, their
miniaturization limit and its dependence on their heterostructures are studied using the
Ginzburg-Landau theory. For a ferroelectric directly formed on a semiconductor, the
depolarization instability is shown to be negligible. To confirm the results, the
depolarization instability is experimentally reexamined. For an insulating ferroelectric
formed on a semiconductor via a thin insulator, the single-domain is destabilized, if there
are no defects or traps. An appropriate number density of the interfacial traps stabilizes the
spontaneous polarization only at one polarity. Alternatively, spontaneous polarization is
stabilized by the semiconductivity of the ferroelectric. This changes the depolarization
instability from destabilization of the ferroelectricity to reduction of the electric flux.
Ferroelectric field-effect transistors (FETs) have the potential for miniaturization and long memory retention,
although the switching speed may be intrinsically limited in conventional ferroelectric/insulator/semiconductor structures.
Excimer-Laser-Produced Single-Crystal Silicon Thin-Film Transistors
Authors: Ryoichi Ishihara Ryoichi Ishihara , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Single-crystal silicon thin-film transistors (TFTs) were fabricated within an ultra-large grain thin film on a glassy substrate which was formed by an excimer-laser crystallization method. The field-effect mobility of the TFTs was 460 cm2/Vs for electrons. The off-current was less than 3 ×10-13 A/µm per unit channel width for a wide range of gate voltages.
Structural Analysis of Cubic GaN through X-Ray Pole Figure Generation
Authors: Krishnan Balakrishnan Krishnan Balakrishnan , Guy Feuillet Guy Feuillet , Kazuo ohta Kazuo ohta , Hiroshi Hamaguchi Hiroshi Hamaguchi , Hajime Okumura Hajime Okumura , Sadafumi Yoshida Sadafumi Yoshida
Published: October 2002

Epilayers of cubic GaN have been grown on (001) GaAs substrates by molecular beam epitaxy using an electron cyclotron resonance (ECR) plasma nitrogen source. In order to study the existence of secondary crystallographic phases in the GaN epilayers, X-ray pole figures were generated on the (001) surfaces of the samples. The exact locations of misoriented cubic and secondary hexagonal phases have been identified and their relative intensities were estimated. The X-ray pole figure technique has been proven to be extremely useful for the structural characterization of cubic GaN epilayers.
Long-Term Performance Modelling of Amorphous Silicon Photovoltaic Module
Authors: Akhmad Kholid , Hiroaki Okamoto Hiroaki Okamoto , Fumio Yamamoto Fumio Yamamoto , Akio Kitamura Akio Kitamura
Published: October 2002

Output performance of the conversion efficiency of an amorphous silicon (a-Si) photovoltaic (PV) module under outdoor conditions has been evaluated for a period of two years. A simplistic model for the change in the module efficiency simultaneously taking into account the light-induced degradation and thermal-recovery effects is applied to the experimental results, yielding several physical parameters describing the degradation and recovery processes. The validity of the model and involved parameters are verified by a good fit between experimental results and model predictions regarding another identical a-Si module which was installed at a different time. By using a modeled seasonal temperature variation, the model is extended to predict the module efficiency for a further long-term period. We showed that the module efficiency becomes almost completely stable after two years of sunlight exposure and then follows a steady seasonal variation.
Preparation of Heavily N-Type ZnSe Doped by Iodine in Remote Plasma Enhanced Metal Organic Chemical Vapor Deposition
Authors: Noda Daiji , Aoki Toru , Yoichiro Nakanishi Yoichiro Nakanishi , Yoshinori Hatanaka Yoshinori Hatanaka
Published: October 2002

Iodine-doped zinc selenide (ZnSe:I) layers were grown by remote plasma enhanced metal organic chemical vapor deposition (RPE-MOCVD) using n-butyliodide (n-BtI). The carrier concentration was controlled from 2×1016 to 8.2×1019 cm-3 by the dopant flow rate, where the mobilities renged from 200 to 50 cm2 V-1 s-1, respectively. The low-resistivity of 7.3×10-4 Ω cm was attained at the highest doping level.
Microwave Characteristics of YBaCuO Coplanar Waveguide Resonators Fabricated by the Sol–Gel Process on Polycrystalline MgO
Authors: Haruichi Kanaya Haruichi Kanaya , Tomohiko Kaneyuki Tomohiko Kaneyuki , Hidehiro Senoh Hidehiro Senoh , Yasuo Cho Yasuo Cho , Ikuo Awai Ikuo Awai
Published: October 2002

High temperature superconducting (HTS) Y–Ba–Cu–O (YBCO) films were prepared on MgO polycrystal substrates by the sol–gel process. The resistivity at DC and the surface resistance (R
s) at a microwave frequency of the films were measured. R
s was found to be highly dependent on the thickness of the films and the temperature, and the optimal value obtained for R
s was 4.2 mΩ at 40 K and 10 GHz. We also fabricated a YBCO coplanar waveguide (CPW) half-wavelength resonator around 2 GHz and compared its RF property with that of a normal metal. The incident power dependence of the transmission characteristics was observed to examine the power handling capability of the HTS resonator. As the temperature and the input power decreased, the quality factor (Q
0) of the YBCO CPW resonator improved significantly, as opposed to hardly any change of that of a normal metal.
Defect Characterization of Sputter Deposited Au Contacts on N-Type Si1-xGex
Authors: Stewart A. Goodman Stewart A. Goodman , F. D. Auret F. D. Auret
Published: October 2002

Sputter deposition of metal Schottky contacts on semiconductors creates damage at and below the surface, often resulting in inferior rectification properties. We have used deep-level transient spectroscopy (DLTS) in an investigation of the electronic properties of defects introduced in n-Si1-
x

Ge

x

(x=0.0 to 0.25) during RF sputter deposition of 500 nm thick Au Schottky barrier diodes (SBDs). Seven discrete electron defects (ES1–ES7) and a band of defects with a continuous distribution were detected after this processing stage. The defects are compared to those detected in the same material after high and low energy alpha-particle irradiation. It was seen that ES5 detected after sputter deposition is actually two peaks superimposed on each other. Contributions from the E-centre and the divacancy make up this DLTS peak. ES5 has a similar DLTS signature to EA2 introduced during high energy (5.4 MeV) alpha-particle irradiation.
Short Cavity All-Solid-State Femtosecond Cr:LiSAF Laser
Authors: Haruyasu Itoh Haruyasu Itoh , Shin-ichiro Aoshima Shin-ichiro Aoshima , Makoto Hosoda Makoto Hosoda , Yutaka Tsuchiya Yutaka Tsuchiya
Published: October 2002

We demonstrate a very short-cavity, all-solid-state Kerr-lens mode-locked Cr3+:LiSrAlF6 laser using various materials of intracavity prisms for dispersion compensation. The minimum size of the laser cavity was 25 ×16 cm using on F8 prism pair material, and almost transform-limited 143 fs pulses were generated at a repetition rate of 262 MHz, which is the smallest femtosecond laser in the world to our knowledge. Changes in the cavity size and pulse repetition rate by changing the prism materials were examined, and the laser was able to generate almost transform-limited pulses shorter than 150 fs in the repetition rate range of 210–262 MHz.