bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Frequency Characteristics of Charge-Injection Transistor-Mode Operation in AlGaAs/InGaAs/GaAs Metal-Insulator-Semiconductor Field-Effect Transistors
Authors: Koichi Maezawa Koichi Maezawa , Takashi Mizutani Takashi Mizutani
Published: February 2005

An AlGaAs/InGaAs/GaAs pseudomorphic metal-insulator-semiconductor field-effect transistor (MISFET) was investigated both in FET- and charge-injection transistor (CHINT)-mode operation. It is demonstrated that a CHINT-mode operation and a large negative differential resistance as well as good FET characteristics can be obtained in MISFETs with a very thin gate barrier layer. Furthermore, the cutoff frequency in CHINT mode-operation was 32 GHz for a MISFET with a gate length of 1 µm. This is about twice as large as that obtained in FET-mode operation. The equivalent circuit analysis revealed that the output conductance and the source resistance play an important role in determining the cutoff frequency, in contrast to ordinary FETs. The intrinsic cutoff frequency (R
s=0) was as large as 57 GHz.
Electron Traps in Si p+nn+ Diodes Created by 10 MeV Electron Irradiation
Authors: Akihiro Yahata Akihiro Yahata , Akio Nakagawa Akio Nakagawa
Published: February 2005

Two electron traps were observed by deep level transient spectroscopy in 10 MeV electron-irradiated Si p+nn+ diodes. The concentrations were nearly equal to each other and were proportional to the radiation flux. The activation energy and electron capture cross section of one trap were 0.13 eV and 2.8×10-18 cm2, respectively. Values for the other trap were 0.39 eV and 3.4×10-16 cm2.
Effects of Plasma Potential on Diamond Deposition at Low Pressure Using Magneto-Microwave Plasma Chemical Vapor Deposition
Authors: Wei Jin , Kawarada Hiroshi , Suzuki Jun-ichi , Jing Shing Ma Jing Shing Ma , Akio Hiraki Akio Hiraki
Published: February 2005

At the low pressure of 0.1 Torr, we have controlled the plasma potential during diamond deposition for the first time using a magneto-microwave plasma chemical vapor deposition (CVD) system. The potential difference between plasma and substrate is an important factor for fabrication of diamond at this pressure. By lowering the plasma potential, high-quality diamond films have been formed. The films were evaluated by scanning electron microscope (SM) imaging, electron diffraction and Raman spectroscopy.
A Capillary Viscometer with a Bellows
Authors: Kobayashi Hiroshi , Kiyoshi Yoshida Kiyoshi Yoshida , Yasumitsu Kurano Yasumitsu Kurano
Published: February 2005

A new capillary viscometer using a bellows as a pressure supplier and a flow meter was developed. After calibration of the viscometer using distilled water, the viscosity of a viscosity standard oil JS 2.5 at 20°C was obtained with the accuracy of a few %.
Hot Electron and Real Space Transfer in Double-Quantum-Well Structures
Authors: Okuno Eiichi , Sawaki Nobuhiko , Akasaki Isamu , Kano Hiroyuki , Hashimoto Masafumi
Published: February 2005

The hot electron phenomena and real space transfer (RST) effect are studied in GaAs/AlGaAs double-quantum-well (DQW) structures, in which we have two kind of quantum wells with different widths. The drift velocity and the electron temperature at liquid helium temperature are investigated as a function of the external electric field applied parallel to the heterointerface. By increasing the field, the electron temperature rises and reaches a plateau in the intermediate region, followed by further rise in the high-field region. The appearance of the plateau is attributed to the RST effect between the two quantum wells. The threshold field for the appearance of the plateau is determined by the difference energy between the quantized levels in two wells. The energy loss rate as a function of the electron temperature indicates that the RST is assisted by LO phonon scattering.
Temperature Distributions Produced in Multilayer Structures by a Scanning CW Laser Beam
Authors: Masayoshi Yamada Masayoshi Yamada
Published: February 2005

Laplace-transformed Green's function solutions to linear heat equations are derived for multilayered structures. An analytic expression for linear temperature distribution produced by a scanning CW elliptical Gaussian laser beam is given in a double integral form and its numerical results are presented. In conjunction with the linear temperature formula, a nonlinear algorithm has been developed in order to incorporate temperature-dependent thermal diffusivity, conductivity, and surface reflectivity. The temperature distributions for the Si/SiO2/Si structure are calculated, including effects of melting of Si. From comparison between the calculation and a measurement on the melting width, it is found that the excess energy absorbed above the melting temperature is spatially redistributed on melting.
Inelastic Electron Tunneling Spectroscopy of Langmuir-Blodgett Monolayers on Silicon Substrate
Authors: Kudo Kazuhiro , Okazaki Choichiro , Shigekazu Kuniyoshi Shigekazu Kuniyoshi , Kuniaki Tanaka Kuniaki Tanaka
Published: February 2005

An inelastic electron tunneling spectroscopy (IETS) technique is employed to investigate Langmuir-Blodgett monolayers deposited on silicon substrates. Thermally formed SiO2 layers are used as a tunneling barrier to obtain reliable and sensitive signals. IETS data, which are compared to IR and Raman data, show the stability and chemical reactions of organic monolayers at the metal or SiO2 interface.
Photochromic Properties of Amorphous WO3 Films
Authors: Yuzo Shigesato Yuzo Shigesato
Published: February 2005

The phoochromic properties of vapor-deposited amorphous tungsten oxide (a-WO3) films have been studied from the viewpoint of their dependence on film structure and water content in the films. The a-WO3 films, prepared under different deposition conditions and postannealing temperatures, were irradiated with uv light (366 nm) at room temperature in vacuum, and the increase in the absorbance of the films was measured. After irradiation for 200 days, the saturation of absorbance was observed for all films, The crystallinity of the framework structure, packing density and total water cohntent were estimated using Raman spectroscopy, X-ray fluorescence and Fourier transform infrared (FTIR) spectroscopy, respectively. Decreasing saturated absorbance of the films was observed with increasing density and decreasing crystallinity of the films.
Film Characteristics of APCVD Oxide Using Organic Silicon and Ozone
Authors: Matsuura Masazumi , Hayashide Yoshio , Hideo Kotani Hideo Kotani , Haruhiko Abe Haruhiko Abe
Published: February 2005

Film characteristics of APCVD oxide using octamethylcyclo tetrasiloxane (OMCTS) and O3 (AP-OMCTS oxide) have been investigated minutely for applications to advanced VLSI devices. Deposition characteristics of AP-OMCTS oxide strongly depend on deposition temperature and high quality films can be formed by increasing the deposition temperature. The step coverage shows a most smooth “flowing profile” around at 425°C. The dependence of the deposition characteristics on O3 concentration can not be observed in contrast with the deposition characteristics of AP-TEOS oxide which evidently depend on the O3 concentration. From these results, it is supposed that CVD reactions based on OMCTS-O3 chemistry consist of the precursor production correspond to CH3 elimination reaction with O radicals and the subsequent polymerization (dehydration) caused by thermal energy provided from hot substrate.
Electrical Properties of Amorphous Si-P/P-Type Si Schottky Barrier Contact
Authors: Toshio Ogino Toshio Ogino
Published: February 2005

Electrical properties of a contact between amorphous silicon-phosphorous solid solution film (a-Si-P) and p-type Si are described. This contact is basically a Schottky contact because a-Si-P is one of the Fermi glasses. Its current-voltage (I-V) and capacitance-voltage (C-V) characteristics, however, exhibit anomalous features differing from those of an ideal Schottky contact. In the I-V curves, the forward current saturates at around 0.4 V, followed by an exponential reincrease in current above 0.5 V. This is interpreted as a charge exchange between the interface states and a space-charge region formed in the a-Si-P electrode. In the C-V curves, an excess capacitance is observed even for reverse bias. The origin of this capacitance is also discussed.
Defects Introduced by MeV-Energy Ion Implantation into Si Probed by a Monoenergetic Positron Beam
Authors: Uedono Akira , Wei Long , Dosho Chisei , Kondo Hitoshi , Tamura Shoichiro Tanigawa
Published: February 2005

Vacancy-type defects in 2-MeV B+-, 2-MeV P+- and 3-MeV As+-ion implanted Si(100) were studied by a monoenergetic positron beam. The depth distributions of vacancy-type defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. The dominant defect species were identified as vacancy-clusters from their characteristic values of the lineshape parameter S. From isochronal annealing experiments for the P+-implanted specimen, two types of oxygen-vacancy complexes were found to coexist even after 1200°C annealing.
Behavior of Miscibility Gaps in the Phase Diagrams of III-V Semiconductor Solid Solutions: Quaternary Systems of the Type AxB1-xCyD1-y
Authors: Tomohiro Onda Tomohiro Onda , Ryoichi Ito Ryoichi Ito
Published: February 2005

The behavior of miscibility gaps in liquid-solid phase diagrams has been studied schematically for III-V semiconductor quaternary solutions of the type A
x
B1-x
C
y
D1-y
such as GaInPAs and AlInPAs. The topological features of the liquidus surface affected by solid immiscibility have been the focus of our examination. Liquidus surfaces below the melting temperatures of the constituent binary semiconductors are presented for typical geometric patterns of a miscibility gap. Liquidus surfaces around the melting temperatures are presented for two typical cases realized in systems such as GaInPAs and AlInAsSb.
High Coercivity Fe-Cr-Co Thin Films by Vacuum Evaporation
Authors: Chin Tsung-Shune , Kou-Her Wang Kou-Her Wang , Cheng-Hsiung Lin Cheng-Hsiung Lin
Published: February 2005

Fe-30Cr-xCo (x=5-30 in 5 wt% intervals) thin films were prepared by vacuum thermal evaporation onto a Si(100) wafer. Isothermal annealing, step aging and continuous cooling were used to anneal the evaporated films, respectively. It was found that isothermal annealing at 620°C followed by continuous cooling to 520°C at a rate of 25°C/h led to optimum films with an intrinsic coercivity (iHc) of up to 740 Oe and residual magnetization (Mr) of up to 780 emu/cm3 for the 50 to 100-nm-thick Fe-30Cr-30Co films. Transmission electron microscopy studies showed that spinodal decomposition occurs during annealing. The shape anisotropy induced by the spinodal structure was found to contribute to the high iHc. The microstructure and magnetic properties of the films were found to be similar to the corresponding bulk materials. The Fe-Cr-Co films were found to be potential candidate materials for magnetic recording.
Electroluminescent Device Made of Diamond
Authors: Fujimori Naoji , Yoshiki Nishibayashi Yoshiki Nishibayashi , Hiromu Shiomi Hiromu Shiomi
Published: February 2005

A diamond light-emitting device was fabricated using boron-doped epitaxial film and a Schottky junction. The emission was white with a spectrum which was quite broad and centered at 530 nm. This spectrum was found to be similar to the spectrum obtained by cathodoluminescence from the boron-doped epitaxial film. The emission is considered to be caused by the injection electroluminescence and the color center named “Band-A” is considered to be the emitted center.
Laser-Beam-Scanning Chemical Vapor Deposition Technique for Controlling the Spatial Thickness Distribution of Thin Films
Authors: Yamada Yuka , Mutoh Katsuhiko , Takashi Iwabuchi Takashi Iwabuchi , Takeo Miyata Takeo Miyata
Published: February 2005

We have developed a laser-beam-scanning chemical vapor deposition (CVD) system using a galvanometer scanner. The basic idea for controlling the spatial thickness distribution of films using the CVD system is discussed. Carbon films with uniform and concave thickness distributions are deposited and the distributions correspond directly to the laser-beam-scanning modes.
Numerical Simulation of the Growth of HgCdTe Layers by Isothermal Vapor Phase Epitaxy
Authors: Lo Jenn-Gee , Lan Hai , Jun-Yuan Chen Jun-Yuan Chen , Luke Su Lu Luke Su Lu
Published: February 2005

A theoretical model of the isothermal vapor phase epitaxy of HgCdTe is presented. The model takes account of the vapor Te2 diffusion limited effect and the chemical reaction limitation to the growth rate of epilayers. We confirm that the chemical reaction cannot be neglected in calculations, and the surface reaction rate constant is estimated to be about 107 µm/h. The compositional profiles under various growth parameters (growth temperature T, growth time t, source to substrate spacing d and mercury partial pressure P
Hg in growth system) are calculated and discussed. From the agreement between the calculated and the experimental profiles, we believe that the model can be used to predict the compositional profiles under various growth conditions.
Growth of Ionic Crystals from Concentrated Aqueous Solutions-Hypothesis of Cation Dehydration and Insertion to Growing Interfaces
Authors: Komatsu Koji Shigematsu
Published: February 2005

The growth of ionic crystals from aqueous solution has been studied by in-situ observation using a microscope. The concentration distributions around the growing crystals, NaClO3 whiskers and NH4Cl dendrites, were measured by multiple-beam interferometry (MBI). In-situ observation of the growth of twelve kinds of alkali salts was carried out under a microscope. It was found that the characteristic growth features, such as growth forms, growth rates and the stability of facets, of those crystals can be arranged in order according to the radii of the cations of each salt. In order to explain the experimental results, a hypothesis of the difficulty of the dehydration of cations was proposed. The difficulty of inserting a cation into various types of kink sites are compared. The characteristic features of the growth form among CsCl, KCl, and NaCl, and characteristics of growth rates among the directions of growing interfaces can be explained by the variation of the difficulty of dehydration.
D-D (H-H) Interactions within the Interstices of Pd
Authors: White C. T. , Brenner D. W. , Mowrey R. C. , Mintmire J. W. , Schmidt P. P. , B. I. Dunlap B. I. Dunlap
Published: February 2005

Embedded atom, local-density-functional, and Hartree-Fock methods are used to calculate the effective interaction between deuterium (or equivalently within the Born-Oppenheimer approximation hydrogen) nuclei within palladium.
No effects were found to suggest that the repulsion between deuterons in gas phase D2 is reduced within the octahedral and tetrahedral interstices of this transition metal.
Smoothing of Silica Glass Surfaces by Ion Implantation
Authors: Oyoshi Keiji , Takashi Tagami Takashi Tagami , Shuhei Tanaka Shuhei Tanaka
Published: February 2005

Enhancement of surface smoothness during ion implantation in rectangularly patterned silica glasses has been observed by scanning electron microscopy. The smoothness of the silica glass surface is significantly improved with increasing ion dose. The efficiency of ion beam smoothing strongly depends on the energy of the incident ion and ion species, whereas it depends weakly on dose rate and temperature. The efficiency of smoothing on the ion energy indicates a maximum when the range of the incident ion corresponds to the height of the rectangular step. Viscous flow is found to be a dominant process from analysis of the change in the surface profile.
Simulation Study of Time-Walk Issues for Drift Tubes
Authors: Asano Yuzo , Itoh Setsuo , Mori Shigeki , Ikeda Hirokazu , Tanaka Manobu
Published: February 2005

Time walk is evaluated for a drift tube of 2.9 cm in diameter filled with P10 gas, with an anode wire of 70 µm in diameter. Its magnitude, if the shaping is of Poisson type and a leading-edge discriminator is used, is found to be 2-10 ns when 50% gain variation is allowed in the gas multiplication. On the other hand, the use of a constant fraction timing discriminator is expected to reduce this to the order of 0.1 ns.
Use of an Electrode Coated with a Thin CuI Layer for Supplying Initial Electrons in Gaseous Discharge
Authors: Tamiya Fujiwara Tamiya Fujiwara , Hiroshi Yamada Hiroshi Yamada
Published: February 2005

An electrode coated with a thin CuI layer has been used to supply initial electrons for gaseous discharge. The number of electrons photoemitted from the electrode is up to 1010 and it is 100 times that before coating. By using the coated electrode the statistical time lags of toroidal discharge have been reduced by about 30% as compared with those observed before coating.
Analysis of Si Schottky Barrier Characteristics Based on a New Interfacial Layer Model
Authors: Maeda Hideaki Ikoma
Published: February 2005

Current-voltage characteristics of Si Schottky barrier diodes are measured at various temperatures between 300 K and 420 K in order to investigate an applicability of a newly proposed interfacial layer model for Schottky barrier. Experimental data are analyzed on a basis of this model. Analyzed results are mostly found to be similar to those of a-Si:H and can be interpreted by the present model. The new interfacial layer model is then concluded to well represent actual Schottky barriers for both amorphous and crystalline semiconductors.
The Resolution Limit of the Resist Silylation Process in i-Line Lithography
Authors: Takehara Daisuke , Ota Tsuneo , Tanimoto Keisuke , Ryohei Kawabata Ryohei Kawabata , Hikou Shibayama Hikou Shibayama
Published: February 2005

The resolution limit of the resist silylation process in an i-line stepper was considered. The method was developed to render the silylated layer visible and was applied to measure the thickness of the silylated layer. The silylated profile is compared with the exposure energy profile and there is good agreement. This result indicates that the degradation of contrast in the silylation is negligible. The dry development process does not limit the resolution because no microloading effect is observed down to the 0.25-µm slit. The degradation of contrast due to optical diffraction is concluded to be essential for determining the resolution. The resolution limit of 0.35 µm in 0.75-µm resist thickness is demonstrated by simulation and experiment.
Determination of the Agglutination Reactions Using Power Spectral Analysis of the Depolarized Light Intensity Fluctuations Scattered from Magnetic Particles
Authors: Namba Akihiro , Yaginuma Yoshinori , Musha Toshimitsu
Published: February 2005

Presented here is a new optical method for evaluating the agglutination reactions of magnetic particles. Light intensity fluctuations scattered from the particles are detected by a cross-polarized optical measurement system. As soon as the electrolyte (NaCl)-induced coagulation of 2 min in a uniform magnetic field is completed, the sample data are gathered under the influence of a half-wave rectified magnetic field. The power spectral density has a strong peak at the frequency of the applied magnetic field. The spectral peak significantly increases by more than 103 with the NaCl concentration in the range between 0.03 and 0.1 mol/l. Furthermore, a sensitive immunoassay by means of magnetic particles can be achieved in a short-time measurement without any complex procedures.
Metalorganic Vapor Phase Epitaxial Growth and Properties of GaN/Al0.1Ga0.9N Layered Structures
Authors: Itoh Kenji , Kawamoto Takeshi , Amano Hiroshi , Kazumasa Hiramatsu Kazumasa Hiramatsu , Isamu Akasaki Isamu Akasaki
Published: February 2005

High-quality, well-controlled GaN/Al0.1Ga0.9N layered structures with periodicity varying from 4.5 nm to 60 nm have been successfully grown on (0001) sapphire substrates by Metalorganic Vapor Phase Epitaxy (MOVPE). The layered structure has been confirmed by double-crystal X-ray diffractometry. Photoluminescence peak energy showed a shift toward the higher-energy side with decreasing thickness of the GaN well layer, which is in good agreement with the calculation obtained from the Kronig-Penny analysis.
Optical Matrix Elements in (110)-Oriented Quantum Wells
Authors: Kajikawa Yasutomo , Masayuki Hata Masayuki Hata , Toshiro Isu Toshiro Isu
Published: February 2005

Optical matrix elements at the Brillouion zone center in (110)-oriented quantum wells (QW's) for linearly polarized light are theoretically investigated on the basis of an envelope-function approximation. For linear polarization parallel to the QW planes, the optical matrix elements in (110) QW's depend on the polarization direction, which is in contrast with polarization-independent character in (001)- or (111)-oriented QW's.
As-Deposited Superconducting Thin Films by Electron Cyclotron Resonance-Assisted Laser Ablation for Application in Micro-Electronics
Authors: Deneffe Kristin , Mieghem Piet Van , Brijs Bert , Vandervorst Wilfried , Robert Mertens Robert Mertens , Gustaaf Borghs Gustaaf Borghs
Published: February 2005

A method for the growth of as-deposited superconducting thin films which combines YAG-laser ablation and oxidation by an electron cyclotron resonance (ECR)-excited oxygen plasma is described. It is demonstrated by depositions on YSZ and SrTiO3 substrates that this one-step method is compatible with the requirements of large surface homogeneity, low substrate temperature and low oxygen partial pressure. The method is therefore well suited for applications in micro-electronics.
Perpendicular Magnetic Recording Performance with Ring-Type Heads for Electroless-Plated CoNiReP/NiFeP Double-Layered Media
Authors: Homma Takayuki , Noda Kazuhiro , Toshihiko Watanabe Toshihiko Watanabe , Tetsuya Osaka Tetsuya Osaka
Published: February 2005

The perpendicular magnetic recording performance of electroless CoNiReP/NiFeP double-layered media using ring-type heads was investigated, focusing upon the recording processes and the effect of underlayer coercivity (H
c
(u)=5∼160 Oe). For the recording on medium whose H
c
(u) value is higher than several tens of Oe, the underlayer is also magnetized by a head field, and the phase of such a longitudinal magnetization of the underlayer is shifted in proportion to the change of magneto-motive force (MMF). In the low MMF region, the phases of perpendicular transition and longitudinal transition are synchronized, forming the horseshoe mode through the perpendicular layer and the underlayer. Consequently, the output voltage, by maintaining single-peak shaped signals, drastically increased by the so-designated “phase synchronization” effect. Greater improvement of reproduced voltage by such a phase synchronization effect was obtained for the higher H
c
(u) medium.
High Gain Characteristics of an Erbium-Doped Fiber Amplifier Pumped in the 800 nm Band
Authors: Kimura Yasuo , Eiji Yoshida Eiji Yoshida , Masataka Nakazawa Masataka Nakazawa
Published: February 2005

The gain characteristics of an erbium-doped fiber amplifier pumped in the 800 nm band have been investigated in detail. The fiber has a dual shape core and the erbium ions are doped only in the inner core to improve the pumping efficiency. The most efficient pumping wavelength is around 820 nm which is determined by the trade off between the decrease in excited state absorption and the decrease in the absorption coefficient. This pumping wavelength makes it possible to achieve an optical gain as high as 40 dB. The noise figures of Er3+-doped fiber amplifiers pumped in the 800 nm band are 4-5 dB in the 1.5 µm signal wavelength region.
Time-of-Flight Pulsed Neutron Diffraction Study on Uniaxial Stress-Induced Domain Switching in LaNbO4
Authors: Horiuchi Hiroyuki , Kobayashi Tadashi , Schultz Arthur J.
Published: February 2005

The domain orientation switching phenomena in the ferroelastlc material LaNbO4 were observed by means of a time-of-flight neutron diffraction technique using a position-sensitive area detector. When stress is applied to the direction nearly perpendicular to (100) of one of the domains in the specimen, the a- and c-axes are easily transformed into the c- and a-axes of another domain, respectively. The domains with [001] nearly parallel to the stress direction do not switch orientation. Thus, the domain which occupied 34% of the specimen at the initial stage expanded up to 92% of the total volume by switching from other orientated domains. The estimated stress was 600 gW/mm2 at the final stage. The mechanism of switching orientation can structurally be interpreted by a small rotation and a small displacement of NbO4 tetrahedra at the domain boundary which is a transient zone with a prototype structure.
Chemical Reaction Processes in Synthesizing CuInSe2 from the Elements by the Melting Method
Authors: Nomura Shigetaka , Ishikawa Jun , Fujio Iinuma Fujio Iinuma , Takeo Takizawa Takeo Takizawa
Published: February 2005

Chemical reaction processes in synthesizing CuInSe2 from the elements are investigated. The powder method of X-ray diffraction has been used to identify the reaction products formed in increasing temperature. Copper is selenized first to be Cu3Se2. Heated further, the Cu3Se2 changes gradually to another copper selenide which is supposed to be Cu7Se4. On the other hand, an indium selenide formed in an indium-deficient part inside the reaction tube is confirmed to be In6Se7, while in an indium-rich part, it is presumably In2Se. Above 500°C, the main body of CuInSe2 begins to be formed from Cu7Se4 as the basis. Cu3Se2 which has not participated in forming CuInSe2 begins to diffuse above 500°C, which is one of the main problems for the stoichiometric control of CuInSe2. The diffused copper selenide also changes to CuInSe2 by absorbing In6Se7 above 600°C.
Decomposition Mechanism of Triethyl-Arsenic on a GaAs Surface for Metalorganic Molecular-Beam Epitaxy: Role of Hydrogen Radicals
Authors: Suemune Ikuo , Hamaoka Kazuhiko , Koui Tomoaki , Akihiro Kishimoto Akihiro Kishimoto , Masamichi Yamanishi Masamichi Yamanishi
Published: February 2005

Growth of GaAs in metalorganic molecular-beam epitaxy using triethyl-arsenic (TEAs) becomes possible only when TEAs is thermally precracked or when hydrogen (H) plasma is irradiated simultaneously. In this paper, it will be shown that the bottleneck in the growth of GaAs with TEAs is the quick desorption of the As-intermediate species before its decomposition to supply As to a GaAs surface. The Ga-stabilized GaAs surface after the TEAs supply is proposed to be covered with stable C2H4 species based on reflection high-energy electron diffraction and quadrupole mass spectrometric measurements. H radicals are shown to be effective in the initial stages of the decomposition process of TEAs, but once the surface is covered stably with C2H4, even the H radicals cannot enhance their desorption.
Effects of Oxygen on the Properties of Sputtered Molybdenum Thin Films
Authors: Tetsuya Yamaguchi Tetsuya Yamaguchi , Ryohei Miyagawa Ryohei Miyagawa
Published: February 2005

The effects of oxygen on film structures and film stresses of sputtered Mo thin films have been investigated. Mo films (8000 Å) were deposited on Si(111) wafers in 0.4 Pa using Ar or Ar+O2 (O2 partial pressure: 0.01 Pa) working gases at 423 K. The major impurity was oxygen, and argon content was below the detection limit (0.05 at.%) of the fluorescence X-ray analysis. Microstructure and film stresses were affected by oxygen. The fibrous grain width in the films was decreased from 40-130 nm with 2.4 at.% oxygen to 40-70 nm with 14.4 at.% oxygen. The high tensile stress, 1×1010 (dyn/cm2) with 2.4 at.% oxygen, changed to the low compressive stress, 1.0×109 (dyn/cm2) with 30.1 at.% oxygen. This paper discusses the relationships between oxygen content and the film structures, and between oxygen content and the film stresses.
A Photon Scanning Tunneling Microscope Using an AlGaAs Laser
Authors: Jiang Shudong , Tomita Naoyuki , Ohsawa Hisaoh , Motoichi Ohtsu Motoichi Ohtsu
Published: February 2005

A novel super-resolution photon scanning tunneling microscope (PSTM) using diode lasers and optical fibers was demonstrated to measure the samples with submicron structure in a noncontact and nondestructive manner. A reproducible method for fabrication of the fiber probe with the tip curvature radius of 80 nm is reported. The step with the height of 9 nm, optical disk with submicron-sized pits similar to moth-eye structure, and latex particles with 80 nm in diameter have been observed. To the best of our knowledge, this is the smallest particle size resolved by the PSTM.
Surface Characterization of Carbon Fibers Exposed to 5 eV Energetic Atomic Oxygen Beam Studied by Wetting Force Measurements
Authors: Tagawa Masahito , Ohmae Nobuo , Umeno Masataka , Yasukawa Akemi , Gotoh Keiko , Tagawa Mieko
Published: February 2005

Changes in contact angle hysteresis and surface free energy of carbon fibers due to the irradiation of 5 eV energetic atomic oxygen beam were investigated. Atomic oxygen with kinetic energy of 5 eV was used in order to simulate the low earth orbit. Contact angle hysteresis in carbon fibers became larger with respect to the fluence of atomic oxygen. Auger electron spectroscopic analysis shows that the hysteresis of the contact angle is proportional to surface oxygen concentration as well as the polar component of surface free energy. Since adsorbed oxygen or the surface functional group plays an important role in the hysteresis, it is clear that the carbon fiber surface was destroyed due to the attack of atomic oxygen.
Preparation and Dielectric and Electrooptic Properties of Bi4Ti3O12 Films by Electron Cyclotron Resonance Plasma Sputtering Deposition
Authors: Masuda Yoichiro , Baba Akira , Masumoto Hiroshi , Goto Takashi , Minakata Makoto , Hirai Toshio
Published: February 2005

Polycrystalline and epitaxlal films of a layer-structured ferroelectric Bi4Ti3O12 in perovskite phases have been deposited on sapphire substrates by ECR plasma sputtering using a sintering ceramic target. The substrate temperature higher than 550°C is necessary to grow Bi4Ti3O12 films in the perovskite phase without post-thermal annealing. Bi4Ti3O12 films were epitaxially grown on C, A and R surfaces of a sapphire single crystal. Refractive indices of Bi4Ti3O12 films were determined from measurements of the Brewster angle, and the dielectric constant was measured at 1 kHz using an ADEX-221A LCR meter.
Preparation and Properties of Lead Zirconate-Titanate Piezoelectric Ceramics Using Ultrafine Particles
Authors: Noboru Ichinose Noboru Ichinose , Masahiko Kimura Masahiko Kimura
Published: February 2005

Ultraflne particles the order of 0.1-µm have been obtained in the system PbTiO3-PbZrO3-Pb(Ni1/3Nb2/3)O3 by a ball-milling method using zirconia balls of 0.3 mm in diameter. This paper describes the electrical and mechanical properties of these modified PZT ceramics using ultrafine particles. The effect of smaller zirconia balls on grinding is clearly demonstrated. Smaller grain size in the sintered bodies of these modified PZT ceramics gives higher flexural strength. However, the maximum electrical properties have been obtained at a grain size of about 2 µm.
A Comparative Study of the Electronic Stability of Hydrogenated Amorphous Silicon and Silicon-Germanium Alloy Material
Authors: Schneider Ulrich , Scholz Andreas , Schröder Bernd , Karg Franz , Kausche Helmold
Published: February 2005

The electronic stability of a-Si:H and a-Si1-x
Ge
x
:H films of different preparations has been investigated by keV-electron irradiation. Employing an electron dose of about 60 J/cm2, a metastable defect density near its saturation value was created. It was found that a-Si:H films exhibiting a high stability, if bulk sensitive measurement techniques (CPM, conductivity measurements) are applied, still have quite a large number of stable surface defects (detected by PDS) whose concentration is raised by irradiation. a-Si1-x
Ge
x
:H alloy films are obviously more stable than pure a-Si:H films, whereby the relative stability increases with the Ge content x. Alloy films containing a small amount of germanium (≈5%) could be of special significance for practical application. The electronic properties of this material are almost identical to those of a-Si:H but the electronic stability is increased.
Displacement Characteristics of Series-Type Bimorph Actuator under High Applied Voltage
Authors: Hayashi Seigo , Ando Akira , Toshihiko Kittaka Toshihiko Kittaka , Yukio Sakabe Yukio Sakabe
Published: February 2005

Experimental and theoretical studies on the applied voltage-displacement characteristics of a piezoelectric series type bimorph were performed. The displacement increased with an increase in the applied voltage until dielectric breakdown. An electric field higher than its coercive field (E
c) can be applied to the bimorph, because its poling direction is opposite to the field, owing to an electric charge balance between its two layers. On the other hand, the displacement of a parallel-type bimorph fell to zero when the applied voltage per unit length equalled E
c. The series-type bimorph displayed larger displacement and higher reliability than the parallel-type bimorph.
Experimental Evaluation Cylindrical Ceramic Tubes Composed of Porous Pb(ZrTi)O3 Ceramics
Authors: Kumamoto Susumu , Mizumura Koichi , Kurihara Yoshiaki , Hiroshi Ohhashi Hiroshi Ohhashi , Kiyonori Okuno Kiyonori Okuno
Published: February 2005

The experimental evaluation of cylindrical ceramic tubes composed of porous PZT ceramics is reported. They exhibit 5.5 dB higher electroacoustic sensitivity and 20% lower resonant frequency than those composed of conventional PZT ceramics.
Relationship between Crystal Structure and Long-Time Response to DC Electric Field in Niobium-Doped BaTiO3 Ceramics
Authors: Ikeda Masaaki , Yoshida Mayumi , Satoh Akira , Nishiyama Kousuke , Izumi Fujio , Asano Hajime
Published: February 2005

The precise crystal structure and its relationship to the electrical properties were investigated for the BaTiO3-CoO-Nb2O5 system. It was observed with X-ray diffraction that the crystal structure changed from tetragonal to pseudo-cubic with the addition of Nb2O5 of more than 0.8 mol%. The lattice structure parameters of a sample containing 0.25 mol% of Co3O4 and 1.0 mol% of Nb2O5 were obtained by two-phase Rietveld refinement using time-of-flight (TOF) neutron diffraction. Ti atoms were displaced from an ideal position at (1/2 1/2 1/2) in the major phase. The change in the crystal structure coincided with a decrease of the degree of capacitance change under a DC electric field, an almost complete disappearance of piezoelectric resonance, and a decrease of the jump in thermal expansion. The pseudo-cubic structure was stable under a DC electric field of 6 V/µm.
Characteristics of the Thick-Film Capacitor Using Pb(Mg1/3Nb2/3)O3-Ba(Ti0.9Zr0.1)O3
Authors: Gejima Seiji , Kawakita Kouji , Suzushi Kimura Suzushi Kimura , Hideyuki Okinaka Hideyuki Okinaka
Published: February 2005

Some properties of a thick-film capacitor which is fabricated through a conventional thick-film processing technique in nitrogen atmosphere are investigated. Pb(Mg1/3Nb2/3)O3 and Ba(Ti0.9Zr0.1)O3, each of which shows different temperature dependence of the dielectric constant according to their Curie points, are employed as dielectric materials for the purpose of obtaining specific properties of the capacitor. Addition of PbO2 as a sintering aid makes it possible for both crystalline phases to coexist in the dielectric layer with no mutual reaction. The temperature dependence of the dielectric constant as a function of composition, the microstructure and the distribution of elements are studied. As a result, it is proved that the mix sintering method is successfully applicable to the temperature dependence of a thick-film capacitor with various properties.
Fabrication of Composite MLC's and Their Dielectric Properties
Authors: Tashiro Shinjiro , Yoshihito Mizukami Yoshihito Mizukami , Hideji Igarashi Hideji Igarashi
Published: February 2005

A new type of composite for multilayer ceramic capacitors (MLC's) was developed in order to improve the temperature dependence of capacitance. The new-type composites were composed of two kinds of dielectric layers laminated alternately, where both dielectric layers, L-layers and H-layers, were composed of lead-based relaxor materials with different Curie points of -30 to -40°C for L-layers and 100 to 120°C for H-layers. In the firing process of the composites, one-way diffusion occurred from H- to L-layers or in the opposite direction through the interfaces between H- and L-layers. The microstructure of the new composites was consequently inhomogeneous. The direction of one-way diffusion depended on the main components of L- and H-layers. The final compositions of L- and H-layers were selected to allow mutual diffusion between L- and H-layers. The temperature dependence of capacitance of the MLC's was less broad than the calculated curves which were derived from that of 2 kinds of ceramics with compositions of L- and H-layers. Composite MLC's with broad temperature dependence were finally formed by laminating the two materials alternately every 5 layers.
Grain Orientation of SbSI Ceramics
Authors: Kazuo Shoji Kazuo Shoji , Yasuo Uehara Yasuo Uehara
Published: February 2005

When SbSI ceramics is viewed as a piezoelectric material, since the direction of the spontaneous polarization is limited to one dimension, it is necessary to perform grain orientation. In this paper, as a method for grain orientation at room temperature, a rolling and an extrusion method are considered, and the fabrication method of SbSI grain-orientation ceramics is examined. Furthermore, the electrical characteristics of the obtained grain-orientation sample are examined.
Quadratic Electrooptic Properties of the Ferroelectric Ceramics of the Ternary System Sr(La1/2Nb1/2)O3-PbZrO3-PbTiO3
Authors: Yokosuka Masaru , Ochiai Tutomu , Masakazu Marutake Masakazu Marutake
Published: February 2005

Optical and electrooptic properties were studied for some compositions of hot-pressed ceramics of the ternary system Sr(La1/2Nb1/2)O3-PbZrO3-PbTiO3. Optical transmittances were measured as a function of wavelength and temperature. Quadratic electrooptic coefficients R and half-wave voltagcs V
π were determined at various temperatures. Switching characteristics were also examined. The results obtained were compared with those of electrooptic crystals such as KTaO3 and KTa0.65Nb0.35O3.
Optical and Electrical Properties of La-Modified (Pb-Ba)Nb2O6 Ferroelectric Ceramics
Authors: Masaru Yokosuka Masaru Yokosuka , Masakazu Marutake Masakazu Marutake
Published: February 2005

Optical and electrical properties, together with phase transitions, were investigated for thc lanthanum-modificd lead-barium metaniobate (Pb1-y
Ba
y
)1-x
La
x
Nb2-x/5O6. Hot-pressed ceramics with compositions near the orthorhombic-tetragonal morphotropic phase boundary were found to have excellent optical characteristics and high piezoelectricity.
Crystal Growth of LiNbO3:Fe and Its Photorefractive Properties
Authors: Ohira Masaki , Chen Zhiming , Tadashi Kasamatsu Tadashi Kasamatsu , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

We have grown LiNbO3:Fe single crystals with different doping concentrations (0.09-0.27 mol%). The homogeneity of Fe in the material was investigated by X-ray microanalysis(XMA) and inductively coupled plasma (ICP) analysis. The optical absorption coefficient increased with doping concentration in the entire wavelength region, and the characteristic band centered around 480 nm was observed. The amplitudes of refractive index change produced by photorefractive two-wave mixing were measured in the initial stage (short-time limit) with respect to the wavelength, the direction of polarization, the intensity of incident laser light and doping levels of crystals.
Preparation and Piezoelectric Properties of Ceramics-Plastic Composite Materials
Authors: Nishida Hiromu Ohuchi
Published: February 2005

Ceramics-plastic composite materials composed of piezoelectric hard materials with properties of high k
33, high Q
M and low s
33
E for the ceramics and epoxy resin for the plastic were prepared. Dielectric and piezoelectric properties for thickness expansion were studied and new piezoelectric ceramics-plastic composite materials with properties of about 1/3 times lower densities (2.61 g/cm3), about 1/10 times lower relative dielectric constant (130), about 10 times higher elastic compliance constant (138.6×10-12 m2/N) and 4.4 times higher piezoelectric voltage constant (101×10-3 V·m/N) than usual ceramics were obtained.
Electrooptic Effect in Homeotropically Aligned Ferroelectric Liquid Crystal
Authors: Ozaki Masanori , Tagawa Akira , Sadohara Yutaka , Shoko Oda Shoko Oda , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

New types of electrooptic effects in a homeotropically aligned cell of ferroelectric liquid crystal have been proposed, and their characteristics have been studied. Especially, in the oblique incident type of the homeotropic cell, a new electrooptic effect with a sharp threshold, very fast response and a hysteresis loop is observed.
Electrically Controlled Second-Harmonic Generation in Ferroelectric Liquid Crystal
Authors: Utsumi Manabu , Gotou Tatsuya , Daido Kazuhiro , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

The angularly phase-matched second-harmonic generation (SHG) in ferroelectric liquid crystal has been studied as a function of electric field strength, sample thickness, rotating angle and temperature. A sharp angular phase-matching curve of the SHG controlled by an electric field is observed even in the liquid crystal. The temperature dependence of the phase-matched SHG in the ferroelectric phase has also been studied, and the temperature-tuned phase matching of SHG is realized by using the change in tilt angle of the ferroelectric liquid crystal.
Hybrid Optical Bistability Using Antiferroelectric Behavior in Ferroelectric Liquid Crystal
Authors: Moritake Hiroshi , Tagawa Akira , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

Hybrid optical bistability with an electrical feedback in surface stabilized ferroelectric liquid crystal which shows
antiferroelectric behavior has been studied. The ac operation of the feedback without dc bias voltage is also realized in the liquid crystal which shows a symmetrical transmission-voltage curve. Dynamic characteristics of the switching between optical bistable states by an incident light pulse have also been studied.
Switching Properties in Antiferroelectric Liquid Crystals
Authors: Yamamoto Norio , Yamada Yuichiro , Mori Kahoru , Nakamura Kouji , Orihara Hiroshi , Ishibashi Yoshihiro , Suzuki Yoshiichi , Negi Yuvraj S. , Kawamura Ichiro
Published: February 2005

The influences of alignment materials on switching properties in antiferroelectric liquid crystals have been studied by using three kinds of polyimide resins. It has turned out that the threshold voltages of the switching between an antiferroelectric state and a ferroelectric state depend on the alignment materials, and that response times are also affected by the alignment materials.
Effect of Iron-Group-Ion Doping on the Properties of BaTiO3 Ceramics
Authors: Inoue Akira , Iha Michiaki , Matsuda Izuru , Hiromoto Uwe Hiromoto Uwe , Tunetaro Sakudo Tunetaro Sakudo
Published: February 2005

The changes of the Curie temperatures of BaTiO3 ceramics doped with Fe, Ni, Cu and Nb were measured from the shifts of the peaks in the permittivity-temperature curves. The corresponding changes of the electrical conductivity were evaluated from the frequency and temperature dependence of the dielectric losses. The various possible causes of the phenomena of the T
c-change were discussed.
An Automated System for Measuring Elastic Properties by the Piezoelectric Resonance Method and Its Applications to Elastic Phase Transitions
Authors: Maeda Masaki , Tachi Hironari , Satoshi Itoh Satoshi Itoh , Ikuo Suzuki Ikuo Suzuki
Published: February 2005

Experiments have been performed to construct an automated system for measuring elastic constants of piezoelectric substances by the piezoelectric resonance method. The measuring system was automated by introducing a network analyzer controlled through a GP-IB interface by a personal computer. The system was applied for investigating the
ferroelectric phase transition of KDP and the ferroelastic phase transition of LAT. Excellent data were obtained for both compounds, and it was confirmed that the measuring system was applicable to the investigation of the phase transitions with large elastic anomalies.
System for Measuring Sound Velocity in Liquid Using Leaky Lamb Wave Modes on 128°Rot. Y-X Cut LiNbO3 Substrate
Authors: Akihiro Sawaguchi Akihiro Sawaguchi , Kohji Toda Kohji Toda
Published: February 2005

A system for measuring sound velocity in liquid is constructed using an interdigital transducer for leaky Lamb waves on a 128° rot. Y-X cut LiNbO3 substrate. The leaky Lamb wave device is composed of a 1-mm-periodicity interdigital transducer and a counter electrode on each surface of the 0.5-mm-thick piezoelectric substrate. The device is operable for 8 modes in the frequency range of 2∼25 MHz at a water-solid interface. The measurement principle of this system uses the interference between a rf pulse signal and a reflected signal. The system successfully measures the absolute sound velocity in some liquid samples. The measurement resolution of the system is within 0.1%.
Theoretical Analysis of Nonlinear Effects in Surface Acoustic Waves on Waveguide
Authors: Yasuhiko Nakagawa Yasuhiko Nakagawa , Tsuyoshi Takanose Tsuyoshi Takanose
Published: February 2005

A ΔV/V surface acoustic waveguide on an anisotropic substrate is analyzed very precisely and the nonlinear component developed on the waveguide is calculated. Then we perform theoretical analysis of 2ω surface acoustic waves which are generated by the above nonlinear component as its excitation forces and propagate in the direction perpendicular to the waveguide.
Effect of Atmosphere on the Wetting of BaTiO3 by Electrode Metals
Authors: Sugihara Sunao , Okazaki Kiyoshi , Terashima Yoshimitsu , Kisamori Katsuhiko
Published: February 2005

BaTiO3 ceramics (with a broad temperature dependence of permittivity) are examined for wetting properties in different atmospheres such as vacuum, Ar and N2. The contact angles were measured with photographs. Ag and Cu showed a contact angle of 90° in a vacuum, and 130° and 105° in Ar, respectively. These metals bonded with the ceramics. However, Pb and Sn had contact angles of 150° and 149° in a vacuum and 138° and 135° in Ar, respectively. The contact angles are discussed with the surface tension of metal as well as the ratio of tension to oxidation potential of a metal. The smaller the ratio, the larger a contact angle is. It was predicted that the metals with smaller ratios, such as Pb and Sn, were easily oxidized by oxygen from BaTiO3 in vacuum, and the oxides are stable, leading to less surface tension. The cross sectional analysis revealed that neither Ag nor Cu diffused into the ceramics.
Optical Activity and Phase Transitions of Fe-I Boracite
Authors: Tomizawa Masahito , Hideaki Sugiya Hideaki Sugiya , Jinzo Kobayashi Jinzo Kobayashi
Published: February 2005

An optical gyration study of Fe-I boracite (Fe3B7O13I) was first made by using the high accuracy universal poralimeter (HAUP) method. Temperature dependence of a gyration tensor component g
12 manifested a sharp peak at the improper ferroelectric phase transition point. We also studied electrogyration effects by applying electric field along the ferroelectric axis. Unusual electric field effects were revealed. For example, an electrogyration coefficient also exhibited a sharp peak at the transition point.