bluuebunny/crossref_metadata_2025 huggingface dataset:
Bias Effect on the Microstructure and Diffusion Barrier Capability of Sputtered TiN and TiOxNy Films
Authors: Ping Jin Ping Jin , Shigeo Maruno Shigeo Maruno
Published: February 2005

The microstructure of TiN and TiO
x
N
y
films deposited on Si(100) substrates in an Ar-N2 or an Ar-N2-O2 gas mixture was evaluated with a high-resolution field emission scanning electron microscope (FE-SEM). The TiN films deposited under an applied negative substrate bias have an extremely dense microstructure with hillocks on the film surface caused by the high compressive stress. The addition of oxygen modifies the microstructure of TiN film, i.e., the hillocks disappeared on the surface of TiO
x
N
y
by virtue of the stress relaxation effect. It has been found through the experiment of internal thermal diffusion by annealing Al/TiN (or TiO
x
N
y
)/Si in a vacuum that the diffusion barrier performance of the films is associated with the microstructure and internal stress in addition to the oxygen content itself.
Evidence for Defect Creation by Light Irradiation in CdSSe-Doped Glass
Authors: Miki Tadaki Miyoshi
Published: February 2005

Time-resolved luminescence spectra and electron spin resonance (ESR) spectra were measured at 300 K and 77 K in CdSSe-doped glass. Intense light irradiation accelerates the decay of luminescence. The change in ESR spectra is indicative of the creation of recombination centers by irradiation.
Performance of Electron Cycrotron Resonance Plasma Produced by a New Microwave Launching System in a Multicusp Magnetic Field with Permanent Magnets
Authors: Hatta Akimitsu , Kubo Makoto , Yasuyoshi Yasaka Yasuyoshi Yasaka , Ryohei Itatani Ryohei Itatani
Published: February 2005

A multi-ring-cusp-type surface magnetic field is tested for production of large-diameter electron cyclotron resonance (ECR) plasma. The density and its distribution are improved by means of a new launching system consisting of an adjustable antenna and a microwave suppressor inserted into the vacuum chamber, which forces the microwave to propagate into the plasma from the stronger side of the surface magnetic fields.
Property of a Microwave Magnetron Plasma Source Inside a Coaxial Line
Authors: Yoshikazu Yoshida Yoshikazu Yoshida
Published: February 2005

A microwave magnetron plasma source which excited the plasma inside the open-end of a coaxial line is described. Experiments are carried out to measure plasma parameters and external circuit elements. The coupling of the plasma and microwave is analyzed for the magnitude of the reflection coefficient. It was found that the self-bias between plasma and inner conductor of coaxial line is dependent on the reactance of the external circuit elements.
Power-Dependent Coupling Characteristics of a Butt Joint between a Single-Mode Planar Waveguide and a Nonlinear Planar Waveguide with Different Film Thickness
Authors: Ono Kazuo , Sakai Tamotsu , Hisashi Osawa Hisashi Osawa , Yoshihiro Okamoto Yoshihiro Okamoto
Published: February 2005

An efficient coupling scheme between single-mode planar waveguides with different film thickness is proposed. The configuration consists of a tapered waveguide with nonlinear cladding. Power-dependent coupling efficiency of the configuration is analyzed by the beam propagation method. The numerical results show that this configuration has high coupling efficiency and is less sensitive to the offset between coupled waveguides when the input power is properly selected.
Etching and Optical Characteristics in GaAs/GaAlAs Surface Emitting Laser Fabrication Using a Novel Spray Etch
Authors: Tanobe Hiromasa , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga
Published: February 2005

We present some results on a novel spray wet etch technique and surface characterization in forming short cavity structures for GaAs/GaAlAs vertical cavity surface emitting lasers. A completely flat epitaxial surface was obtained for the output-side mirror by selectively removing the GaAs substrate. The surface reflectivity was uniform and the reproducibility was drastically improved.
High-Precision Measurement for Refractive Index Distribution and Dispersion Using an Improved Scanning Total Reflection Method
Authors: Hashimoto Takeshi , Matsuzaki Hiroshi , Hirofumi Tsuchida Hirofumi Tsuchida , Kimiaki Yamamoto Kimiaki Yamamoto
Published: February 2005

An improved scanning total reflection (STR) method is discussed to accurately measure the refractive index distribution and dispersion of the gradient index optical element. We also describe the measuring apparatus and experimental results. The accuracy of 1×10-4 (rms) was attained in terms of the absolute measurement of refractive indices, and good reproducibility of the index and Abbe number were also confirmed, δn=1×10-4 (rms) and δνd=0.5 (rms), respectively. A very good agreement is also observed between the result obtained by our method and that by an interference method.
Y-Branch TE-TM Mode Splitter Using Multilayered Waveguide
Authors: Koji Matsubara Koji Matsubara , Hiroyoshi Yajima Hiroyoshi Yajima
Published: February 2005

A Y-branch TE-TM mode splitter using a multilayered waveguide is proposed. This mode splitter is based on a form birefringence which is inherent in a multilayered medium. Owing to its form birefringence, the multilayered waveguide has different propagation characteristics for different polarizations. The Y-branch waveguide in which one branch arm is multilayered results in efficient TE-TM mode splitting operation. An example of the numerical design is shown and the field propagation and the extinction ratios of the splitter are calculated using the coupled mode equations. The calculated extinction ratios for TE and TM modes are -47.92 dB and -33.55 dB, respectively, with a branching angle of 0.06 degrees. The device was fabricated and mode splitting operation was observed.
Estimation of Critical Thicknesses and Band Lineups in ZnCdSe/ZnSSe Strained-Layer System for Design of Carrier Confinement Quantum Well Structures
Authors: Wu Yi-hong , Ichino Kunio , Kawakami Yoichi , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: February 2005

For the fabrication of practical single and multiple semiconductor quantum wells (QWs) capable of confining carriers in the well layers, it is essential that the compositions and thicknesses of constituent layers be suitably chosen to yield sufficiently large conduction and valence band offsets between well and barrier layers, and to avoid lattice relaxation. In this paper we present a guideline for the design of strained-layer ZnCdSe/ZnSSe carrier confinement QWs which satisfy such requirements, based on the estimations of critical thicknesses and band lineups of the structures. From the results obtained here, ZnCdSe/ZnSSe QWs are demonstrated to be eminently suitable for applications to optoelectronic devices operating in the blue-green region of the spectrum.
Enhanced Growth of Thermal Oxide Due to Impurity Absorption from Adjoining Contaminated Silicon Wafers
Authors: Yamamoto Hirofumi Shimizu
Published: February 2005

Enhanced growth of thermal oxide at high temperature is investigated when a silicon wafer is situated behind an adjoining contaminated one. Impurities reside on the back surface of the wafer due to chucking with a stainless steel plate, depending on the surface roughness. During oxidation, the impurities spread to the adjoining wafers, causing enhanced oxide growth with the convex side up in profile. Chromium and nickel are possibly responsible for this process.
Raman-Scattering Properties of I-III-VI2 Group Chalcopyrite Semiconductors
Authors: Matsushita Hiroaki , Saburo Endo Saburo Endo , Taizo Irie Taizo Irie
Published: February 2005

The Raman-scattering spectra of I-III-VI2 group chalcopyrite semiconductors and their solid solutions were measured. The frequency relationship for the A1 vibrational mode agrees with the simple ratio of the anion atomic weights, although it also depends on the mean atomic weights of the cations. Compositional change of the A1 mode frequency for their solid solutions with anion substitution can be explained by the probability of formation of two pairs of anion atoms.
Luminescence of Sintered Ca2B5O9Cl:Eu2+ Excited by UV-Light or X-Rays
Authors: Nakamura Shoichi , Katsuyuki Inabe Katsuyuki Inabe , Nozomu Takeuchi Nozomu Takeuchi
Published: February 2005

Sintered Ca2B5O9Cl:Eu2+ is prepared and the photoluminescence caused by UV-light (PL) and X-ray fluorescence (XFL) are measured at various temperatures and compared with thermoluminescence (TL). The XFL as well as the TL is mainly attributed to the electronic 4f65d to 4f7 transition in Eu2+ ions due to the recombination of free electrons with Eu3+ ions formed by X-rays, in contrast to the PL which is caused merely by the optical excitation of Eu2+ ions.
Application of the Gas Evaporation Method to Observation of Magnetic Domains
Authors: Tomoaki Sakurai Tomoaki Sakurai , Yutaka Shimada Yutaka Shimada
Published: February 2005

Fine Fe particles produced by evaporation in Ar gas are applied to the observation of magnetic domains. Results of fundamental investigations of the patterns formed by the particles are described. Domain patterns of a Sm-Co polycrystalline magnet and magneto-optically recorded bit patterns in Tb-Fe-Co films are observed by this method. The results are compared to the patterns obtained by the Bitter colloid method and discussion is presented on the prospective improvement of the resolution.
Preparation of Microcrystalline Silicon Films by Very-High-Frequency Digital Chemical Vapor Deposition
Authors: Masanori Otobe Masanori Otobe , Shunri Oda Shunri Oda
Published: February 2005

A novel method of growing microcrystalline silicon, called “VHF digital CVD”, which consists of five steps, (i) nuclear formation, (ii) a-Si deposition, (iii) annealing for crystallization, (iv) grain boundary passivation, and (v) grain size limitation, is proposed. Microcrystalline silicon films have been fabricated by repeating step (ii) with VHF plasma-enhanced CVD using a gaseous mixture of SiH4 and H2, and step (iii) with hydrogen plasma. These films have been characterized by means of Raman spectroscopy, X-ray diffraction, infrared absorption, dark- and photo-conductivity, and transmission electron microscopy. We discuss the transformation of the structure from amorphous to microcrystalline in connection with annealing time, film thickness, and deposition temperature. The diffusion of hydrogen radicals is the rate-limiting process for crystallization.
Effect of Substrate Bias on Silicon Thin-Film Growth in Plasma-Enhanced Chemical Vapor Deposition at Cryogenic Temperatures
Authors: Shin Hidetoshi , Okamoto Katsuhiko , Seiichi Miyazaki Seiichi Miyazaki , Masataka Hirose Masataka Hirose
Published: February 2005

The ion irradiation effect on a growing silicon surface in a silane plasma has been studied at a substrate temperature of -110°C, where the thermal reaction is basically quenched. The ion flux and mean energy have been varied by employing a triode reactor in which dc bias is applied to the substrate electrode. It is shown that ion bombardment interrupts the surface polymerization reaction and causes the desorption of deposition precursors. By reducing ion bombardment, the deposition precursors on the surface were liquified, and hence film growth proceeded selectively from the groove bottoms on the fine-patterned surface.
SiO2 Etching Characteristics with Low-Energy Ions Generated by Electron Cyclotron Resonance Plasma Using CF4 and NF3 Gases
Authors: Fujiwara Nobuo , Miyatake Hiroshi , Yoneda Masahiro , Kazuo Nakamoto Kazuo Nakamoto , Haruhiko Abe Haruhiko Abe
Published: February 2005

We report on the basic investigations of SiO2 etching characteristics in low ion energy regions using electron cyclotron resonance (ECR) plasma. The SiO2 etch rate is enhanced by higher microwave power and higher pressure, but it is not dependent solely on the ion current density. In the case of NF3 plasma, the ion sheath potential depends only on pressure, and the ion current density shows a strong dependence on the distance between the ECR region and the wafer. The yield of SiO2 etched with NF3 plasma increases as the distance increases. The etching yield of SiO2 strongly depends on the ion energy and the flux ratio of neutrals to ions.
Mechanisms of Surface Reaction in Fluorocarbon Dry Etching of Silicon Dioxide-An Effect of Thermal Excitation
Authors: Ikegami Naokatsu , Ozawa Nobuo , Miyakawa Yasuhiro , Norio Hirashita Norio Hirashita , Jun Kanamori Jun Kanamori
Published: February 2005

Ion bombardment-induced thermal reaction between a fluorocarbon adlayer and a SiO2 surface in a reactive-ion-etching (RIE) environment which was simulated in an ultrahigh-vacuum thermal desorption mass spectroscopy (TDS) apparatus has been studied. The RIE-induced fluorocarbon chemisorbed layer, covering the SiO2 surface, was observed to be thermally stimulated to react chemically with the SiO2 in the TDS apparatus with an activation energy of approximately 1.9 eV. A terminal group, chemisorbed at the adlayer/SiO2 interface, could be an active participant in the thermal reaction. This observation indicates the possibility that chemical sputtering could occur in the actual RIE through a thermal excitation step, induced by ion bombardment. A significant difference in the RIE-induced mixing of fluorine atoms between SiO2 and Si also appeared in their TDS spectra.
A Dry Process for Stripping As+ Ion-Implanted Photoresist
Authors: Masashi Kikuchi Masashi Kikuchi , Richard Bersin Richard Bersin
Published: February 2005

A dry single-wafer process for the stripping of As+ ion-implanted photoresists has been developed. The process utilizes a combination of reactive ion etching (RIE) and remote microwave plasma chemical processing. The implanted arsenic is removed through conversion to a volatile compound after removal of the organic matrix.
Two-Dimensional Electron Gas Mobility Enhancement in Inverted GaAs/n-AlGaAs Heterostructures Grown by Molecular Beam Epitaxy
Authors: Yoon Soon Fatt Yoon Soon Fatt
Published: February 2005

Electrical properties of an inverted heterojunction interface in GaAs/n-AlGaAs heterostructures selectively doped with Si were investigated. It was found that the effect of mobility reduction normally observed in such structures can be overcome by suppressing Si doping in the AlGaAs layer and increasing the spacer layer thickness. The results indicate a strong contribution, based on a diffused profile of doped Si impurities in the GaAs channel and AlGaAs spacer, resulting from surface segregation. Large enhancement of two-dimensional electron gas (2DEG) mobility at low temperature was achieved in an inverted heterostructure at a low Si doping concentration (N
d=3×1017 cm-3) and spacer thickness exceeding 100 Å. The highest mobility value obtained was 5×104 cm2/V·s at 77 K, with an interface carrier density N
s of around 1.7×1011 cm-2.
Reliability of Dielectric Layers for Magneto-Optical Storage Media
Authors: Tabata Masahiro , Warren Garry W. , Guilian Gao Guilian Gao
Published: February 2005

AlN, SiAlN and SiN films have been studied for use as the Kerr rotation enhancing and protective films of the magneto-optical (MO) storage media. Electrochemical tests (cyclic voltammetry) and high temperature, high humidity chamber tests have been carried out in order to evaluate the reliability of the dielectric layers. An AlN dielectric layer shows improved reliability due in part to a greater resistance to microcracking resulting from delicate internal stresses in the films. A SiN layer has a significant advantage for use as a protective film, reducing moisture penetration. An optimum configuration of dielectric layers on a quadri-layered MO medium is proposed for improved reliability performance.
Multiple-Object Discriminant Filter Generated by Simulated Annealing
Authors: Taniguchi Masaki , Matsuoka Katsunori , Yoshiki Ichioka Yoshiki Ichioka
Published: February 2005

A method of generating a new type of multiple-object discriminant filter, of which the filter function has discrete values, is presented. In order to reduce the error in peak-correlation response of a quantized synthetic discriminant function filter, the simulated annealing technique is used for filter design. As a result, the error is greatly reduced. Results of computer simulations are demonstrated.
Study of Surface Processes in the Digital Etching of GaAs
Authors: Ishii Masashi , Meguro Takashi , Kodama Hirokazu , Yamamoto Yasuhiro , Aoyagi Yosinobu
Published: February 2005

Surface processes in GaAs digital etching using alternating incidence of Cl radicals and a low energy Ar ion beam are discussed. For Cl feed time greater than 0.3 s, etching of GaAs does not proceed for short Ar ion irradiation times. This etching delay time is about 3 and 7 s for Cl feed time of 0.5 and 0.7 s, respectively. After etching starts, the etch rate increases and finally saturates during Ar ion irradiation. Since the same saturation value was obtained for Cl feed times between 0.5 and 0.7 s, digital etching involves a self-limiting mechanism. Rate equation analysis can explain these unique characteristics of digital etching on the assumption that physisorbed Cl layers prevent the sample surface from etching during short Ar ion irradiation times.
Step Structures and Terrace Width Ordering of Molecular Beam Epitaxially Grown GaAs Surfaces Observed by Scanning Tunneling Microscopy
Authors: Tanaka Ichiro , Shunsuke Ohkouchi Shunsuke Ohkouchi , Akihiro Hashimoto Akihiro Hashimoto
Published: February 2005

We have observed the surface structures of molecular beam epitaxially (MBE) grown 30-monolayer (ML) GaAs on vicinal (001) surfaces using a multichamber ultrahigh-vacuum scanning tunneling microscope (STM). Only A-type step edges (parallel to the [11̄0] direction) were found in the STM images of vicinal surfaces cut toward [111]A (A-surface). Not only B-type step edges (parallel to the [110] direction), but also A-type step edges were observed on vicinal surfaces cut toward [111]B (B-surface); that is, wide terraces bordered by B-type step edges and narrow terraces bordered by A-type step edges co-existed on the B-surfaces. The B-surface structure is, thus, less uniform than that of the A-surface. We performed further MBE growth on the nonuniform B-surface under the step-flow condition. The surface structure evolved to be more uniform with growth.
Auger Electron Spectroscopy and X-Ray Diffraction Study of Interdiffusion and Solid State Amorphization of Ni/Ti Multilayers
Authors: Tadayyon Seyed Mohammad , Osamu Yoshinari Osamu Yoshinari , Kazuhide Tanaka Kazuhide Tanaka
Published: February 2005

The process of interlayer diffusion and solid-state reaction in Ni/Ti multilayer films during annealing at 523-623 K has been investigated by Auger electron spectroscopy depth profiling (AESDP) and grazing incidence X-ray diffractometry. Samples were prepared by alternate evaporation of Ni and Ti on Si(111) substrate. The interdiffusion coefficients evaluated from the AESDP give reasonable values for the process. X-ray diffractographs show that the interfaces are altered into amorphous alloys, which induces a compressive internal stress within hcp Ti sublayers manifesting (002) preferred orientation, and causes characteristic shifts of the Ti Bragg peaks.
Observation of Superstructures Induced by Ag Adsorption on a Si(110) Surface
Authors: Youiti Yamamoto Youiti Yamamoto
Published: February 2005

The Ag/Si(110) system has been studied by RHEED-TRAXS (reflection high-energy electron diffraction-total reflection angle X-ray spectroscopy). The (9, 3)×(9̄,3) and 5×4 structures were formed depending on the amount of Ag adsorption. When Ag adsorbed to 2.47 monolayers or more, Ag crystals grew epitaxially in the StransKi-Krastanov mode. A two-dimensional phase diagram was made for this system.
{111} Facet Formation during Lateral Solid-Phase Epitaxy of Silicon
Authors: Ueno Tomo , Kawai Kenji , Morisawa Toru , Hatano Takahiro , Kunii Yasuo , Iwao Ohdomari Iwao Ohdomari
Published: February 2005

A model for {111} facet formation during lateral solid-phase epitaxy (L-SPE) along the <100> direction has been proposed. Based on the experimental fact that the SPE growth rate along the <110> direction is higher than the <111> direction by a factor of seven, it is concluded that, at the very base of a V-shaped SPE front delineated by {111} facets, SPE takes place predominantly along the <110> direction unless there are obstacles. This would eventually bury the V-shaped valley and the flat {110} facet would be resumed. In order to match this view with the well-known fact that the flat {110} facets never recover once the folded {111} facets are formed, we must assume that there are some obstacles which cause and sustain the folded {111} facets. Via plan-view transmission electron microscopy (TEM) observation we have found that the obstacle is the polygrains which have grown randomly in the amorphous Si region due to heterogeneous nucleation.
Stacking Fault Induced by Gold Diffusion in Silicon
Authors: Morooka Masami , Hashimoto Manabu Takahashi
Published: February 2005

Gold was diffused into several silicon single crystals at 1150°C and hexagonal stacking faults were induced in some crystals by the gold diffusion. The relationship of the stacking fault formation to the gold diffusion was investigated. The stacking faults were formed in a region greater than about 100 µm from the specimen surface and increased in the inner part to a constant value greater than 300 µm. The stacking fault size and number increased with the substitutional gold concentration but only their number decreased with the decrease of the gold concentration. The number of point defects contributing to the growth of stacking faults was nearly equal to that of substitutional gold atoms diffused into silicon, and the stacking fault contained one atomic layer of point defects. The reaction between the nucleus of stacking faults and the point defects was not uniformly distributed, but was instead localized.
Adsorption and Desorption of Metallic Impurities on Si Wafer Surface in SC1 Solution
Authors: Ryuta Jiro , Yoshimi Toshihiro , Kondo Hideyuki , Shimanuki Hitoshi Okuda
Published: February 2005

Variation in the surface concentration of Fe, Ni, Cu and Zn on Si wafers due to treatment in NH4OH/H2O2/H2O solution is investigated. It is shown that adsorption and desorption of the metallic impurities occur simultaneously in the solution. The metal concentration on the wafer surface depends on the initial surface concentration, concentration in the solution, adsorption probability, desorption rate constant and the treatment time. The measured surface concentration is explained by taking into account the effects of these parameters. The variation in the desorption rate constant with the metal species, treatment temperature and the concentration in the solution is discussed.
Modeling the DC Performance of Heterostructure-Emitter Bipolar Transistor
Authors: Lour Wen-Shiung , Liu Wen-Chau , Guo Der-Feng , Liu Rong-Chau
Published: February 2005

A theoretical model related to minority carrier properties was developed to study the DC performance of a heterostructure-emitter bipolar transistor (HEBT) which uses an AlGaAs/GaAs heterojunction only for minority carrier confinement and causes improved emitter electron injection efficiency. In this study, minority carrier properties were described by means of polynominal fit to the previous data. Here, the band-gap shrinkage in heavily doped layers was also taken into account. On the other hand, current gains of 55 and 180 were achieved experimentally for an HEBT with Al0.3Ga0.7As and Al0.5Ga0.5As confinement layers, respectively. It is found that the calculated data were agree with the experimental results. With the reduction of the base width to 0.1 µm, a common-emitter current gain of around 1000 with small offset voltage was confirmed. These results reveal that the HEBT exhibits the feature of simplicity and excellent DC performance.
Time-Resolved Luminescence Spectra of Porous Si
Authors: Miyoshi Tadaki , Lee Kyu-Seok , Aoyagi Yoshinobu
Published: February 2005

Time-resolved luminescence spectra of porous Si were measured under an N2 laser excitation. The luminescence shows a nonexponential decay with an initial time constant of less than 5 ns and more than 200 ns for the secondary decay. The luminescence is considered to be associated with localized states, which are probably conduction and valence sublevels in Si microstructures.
Conceptual Design Studies of a Laser Diode Pumped Solid State Laser System for the Laser Fusion Reactor Driver
Authors: Naito Kenta , Yamanaka Masanobu , Nakatsuka Masahiro , Kanabe Tadashi , Mima Kunioki , Yamanaka Chiyoe , Sadao Nakai Sadao Nakai
Published: February 2005

We have developed a conceptual designing technique of a laser diode pumped solid state laser system having high peak power, high efficiency, good beam quality, and high repetition rate. Using this technique, we evaluated the feasibility of the systems with several solid state laser materials for the laser fusion reactor driver with 10 MJ blue output, 10% overall efficiency, and 10 Hz repetition rate. The systems with such as HAP4 glass, Nd:SiO2 glass, Nd:Y:CaF2 crystal, and Tm, Ho:YAG crystal are shown to be attractive candidates for the reactor driver while the systems with such as LHG8 glass, Nd:YAG crystal, and Tm:YAG crystal will not be selected as the candidates. For an economical laser fusion reactor driver, the solid state laser materials are required to have the following properties; \hbarω/σ∼10 J/cm2 (\hbarω: the laser photon energy, σ: the stimulated emission cross section), a thermal shock parameter of ≥3 W/cm, a nonlinear index of refraction smaller than ∼3×10-13 esu, and a fluorescence lifetime of ≥4 ms.
Gain Measurement of a Free Electron Laser on the UVSOR Storage Ring
Authors: Takano Shiro , Hama Hiroyuki , Isoyama Goro , Lin Akihiko , Vinokurov Nikolay Alexandrovitch
Published: February 2005

We report the results of gain measurement of a free electron laser at a wavelength of 488 nm made on the UVSOR storage ring. In this experiment, a conventional transverse undulator made of permanent magnets is employed, and the storage ring is operated at the energy of 500 MeV in the single-bunch mode. The measured peak gain is 8×10-4 for the average beam current of 10 mA, which agrees well with gain estimated from theory.
Luminescence of N-Implanted In0.32Ga0.68P Grown by Liquid-Phase Epitaxy
Authors: Wu Meng-Chyi , Chyuan-Wei Chen Chyuan-Wei Chen , Li-Kuang Kuo Li-Kuang Kuo
Published: February 2005

The photoluminescence spectra of N-implanted In0.32Ga0.68P epitaxial layers grown on GaAs0.61P0.39 substrates by liquid-phase epitaxy have been investigated at different annealing temperatures and times by the rapid thermal annealing technique. The nitrogen level is located ∼110 meV below the Γ-band minimum for the In0.32Ga0.68P crystal. The activation energy necessary to place N atoms into sites to form the N-isoelectronic trap is 0.47 and 0.48 eV in Ar and N2 ambients, respectively. The optimum post-implantation annealing condition to obtain the maximum isoelectronic trap emission intensity is at 800°C for 30-s duration in both Ar and N2 ambients.
Production of YBa2Cu3O7-x Thick Films on Ag Metal Substrate Controlled by Oxygen
Authors: Masuda Yoshio , Matsubara Kazuo , Rikuro Ogawa Rikuro Ogawa , Yoshio Kawate Yoshio Kawate
Published: February 2005

YBa2Cu3O7-x
superconducting thick films were formed on Ag substrate using the sol prepared from pertinent metal alkoxides. The firing conditions which cause incongruent melting and a peritectic reaction in the film were investigated. We call this the IMPERCO (incongruent melting and peritectic reaction controlled by oxygen) method. It has been found that films which undergo both reactions have excellent superconducting properties. Accordingly, the critical current density (J
c) of 1.18×104 A/cm2 at 77 K and zero magnetic field has been obtained. Roles of the boundary of the film and Ag substrate were also discussed.
Thermal Crystallization of Copper Indium Diselenide Film with Oxygen-Doped Layer
Authors: Yamaguchi Toshiyuki , Matsufusa Jiro , Yoshida Akira
Published: February 2005

Copper indium diselenide films with the structure of an oxygen-doped layer on a nondoped layer were deposited by vacuum evaporation and crystallized thermally. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XPD) studies show that CuInSe2 and In2O3 are mixed on the upper side of the annealed films, while the bulk of the film is comprised of single-phase CuInSe2. The properties of the films after the chemical treatment for removing the mixed phase have been investigated. The films annealed above 500°C have a chalcopyrite structure. All the films show p-type conduction. The resistivity, photosensitivity, and activation energy of the films increase with increasing annealing temperature. The density of trapping centers in the film annealed at 650°C is 1.08×1010 cm-2. The band gap observed in the absorption spectra is around 1.0 eV. It is possible to improve the characteristics of CuInSe2 films by means of this process.
Transient Behavior in ZnS:TbFx Thin-Film Electroluminescent Devices Excited by Very Short Pulse
Authors: Miura Noboru , Hironaga Matsumoto Hironaga Matsumoto , Ryotaro Nakano Ryotaro Nakano
Published: February 2005

The transient characteristics in ZnS thin-films doped with Tb3+ ions under an alternating pulse voltage with very short width were measured. The emission from the Tb3+ ion saturated within the applied pulse voltage. Broad-band emission intrinsic to the ZnS host was observed in the wavelength region from 320 nm to 700 nm with very short lifetime. The 545 nm emission of the ZnS:TbF
x
device is separated into the emission from the ZnS host and the Tb3+ ion. The Tb3+ emission appeared in the decay of the broad-band emission. The transient behavior of the photoluminescence excited by the N2 laser showed similar characteristics. These results were also observed in the ZnS:Mn EL device.
Si- and Ge-Doped GaN Films Grown with GaN Buffer Layers
Authors: Nakamura Shuji , Takashi Mukai Takashi Mukai , Masayuki Senoh Masayuki Senoh
Published: February 2005

Si- and Ge-doped GaN films were grown with GaN buffer layers. Si-doped GaN films, of which the carrier concentration was as high as 2×1019/cm3, were obtained. Every Si-doped GaN film showed a surface morphology that was smooth and mirrorlike. Ge-doped GaN films, of which the carrier concentration was as high as 1×1019/cm3, were obtained. Surface morphology of Ge-doped GaN films became poor around this carrier concentration. Both dopings showed good linearity of the carrier concentration as a function of the flow rate of GeH4 and SiH4. Therefore, Ge and Si are suitable n-type dopants for GaN.
Coupling to Lower Hybrid Waves with the Multijunction Grill
Authors: Kazunori Matsumoto Kazunori Matsumoto , Kunizo Ohkubo Kunizo Ohkubo
Published: February 2005

Coupling characteristics of the multijunction grill have been studied in detail by experiments on the basis of a simple theory using a multireflection method with the aid of scattering matrices not only at the junction plane but also at the grill mouth. Theoretical values of the global reflection coefficients in the primary waveguide and secondary waveguides are estimated from the vector sum of reflecting components caused by each reflection between two scattering planes. The experimental results of scattering matrices and global coupling agree well with theoretically calculated ones. It is shown that the multiple reflection in secondary waveguides of the four-junction grill for the JIPPT-IIU tokamak is finished up to three or four reflections. The length of the secondary waveguide is confirmed to be one of the parameters determining the grill efficiency.
Time-Resolved Electron Energy Analyzer
Authors: Hirano Katsumi , Asami Kouji , Makoto Shindo Makoto Shindo , Toshikazu Yamamoto Toshikazu Yamamoto
Published: February 2005

An electron energy analyzer is designed for time-resolved measurement of pulsed energetic electron beams whose energy is in the range from 200 keV to several MeV, and successfully used to obtain energy distribution of the electron beam generated by a plasma focus device. The beam detection system is based on the Cerenkov effect. The radiation is detected by six photomultipliers through optical fibers mounted at different angles which depend on the electron energy. For the optical medium, Lucite is employed. Energy resolution of the detector is presented as a function of the electron energy. The signal ratio of the Cerenkov radiation to the scintillation by X-rays, which is always produced with a high-temperature plasma, is evaluated experimentally.
A Study on IR Light Intensities Scattered from Defects in an Indum-Doped Liquid Encapsulated Czochralski GaAs Crystals as Functions of Wavelength and Intensity of Bias Light Superposed on the Defects
Authors: Sakai Kazufumi , Ryuichi Hashimoto Ryuichi Hashimoto , Tomoya Ogawa Tomoya Ogawa
Published: February 2005

IR light intensity scattered from particles precipitated on dislocations in an indium-doped GaAs crystal is studied by superposing monochromatic light as a bias. The bias light makes clear change of the scattered intensity at 1050 nm and 1290 nm which coincides with the energy levels of EL2 observed by the photoluminescence method. The experimental results indicate that the precipitates on dislocation lines are a type of EL2 defect.
Microstructure of Alkoxide-Prepared Lead Zirconate Titanate Actuator
Authors: Okada Nagaya , Ishikawa Kenji , Murakami Kenji , Nomura Takashi , Hagino Minoru , Nishino Naoya , Kihara Utsuo
Published: February 2005

A low-hysteresis lead zirconate titanate (PZT) actuator with fine-grained ceramics is realized by an alkoxide method followed by a hot isostatic press (HIP) or a hot-press method. The HIP or the hot-press method is effective for increasing the density of the fine-grained actuator without further grain growth. It is concluded from the transmission electron microscopy (TEM) observations that the fine-grained ceramics are composed of grains with a size of around 1 µm, which include still smaller particles ranging from 20 nm to 50 nm in size. The smaller particles seem to be traces of the boundaries of the alkoxide-prepared starting powders. The improved hysteresis characteristics may be related to the traces left in the component grains.
Transmitting Properties of Porous Pb(Zr, Ti)O3 Transducer
Authors: Kurihara Yoshiaki , Koichi Mizumura Koichi Mizumura , Hiroshi Ohashi Hiroshi Ohashi
Published: February 2005

The displacement characteristics of the applied voltage on porous-Pb(Zr, Ti)O3 (P-PZT) are measured by the laser interferometry system. The static displacement characteristics are measured by applying DC voltage to avoid the interference from the various vibration modes. Also, the dynamic displacement characteristics are measured by applying AC voltage of the resonance frequency at 200 kHz. These displacement characteristics showed a dependence on the porosity of P-PZT, and the displacements increased as the porosity of P-PZT increased. P-PZT is applied to the echo sounder to evaluate the transmitting properties in water, and the improved transmitting sensitivity of 3.5 dB in reference to the conventional (nonporous) PZT, is obtained when the porosity of P-PZT is increased to 27%.
Thin Rotary and Linear Ultrasonic Motors Using a Double-Mode Piezoelectric Vibrator of the First Longitudinal and Second Bending Modes
Authors: Tomikawa Yoshiro , Takano Takehiro , Umeda Hidenobu
Published: February 2005

This paper deals with thin rotary and linear ultrasonic motors using a double-mode piezoelectric ceramic vibrator; a rectangular plate vibrator of the first longitudinal and second bending modes is utilized. A specific merit of the motors is that their thickness can meet the restriction of 10 mm, which is one of the practical requirements of a light load gearless motor. The rotary motor is intended for application in card forwarding, and the linear motor, in magnetic-head traveling and so on. Construction and characteristics of the motors are described herein.
Superlattice and Dielectric Properties of BaO-R2O3-TiO2 (R=La, Nd and Sm) Microwave Dielectric Compounds
Authors: Ohsato Hitoshi , Nishigaki Susumu , Takashi Okuda Takashi Okuda
Published: February 2005

Dielectric crystals having composition in the vicinity of Ba3.75
R
9.5Ti18O54 and/or BaR
2Ti4O12 (R=La, Nd and Sm) were obtained from the melts with BaR
2Ti5O14 composition. A superlattice with two times the fundamental lattice spacing along the c-axis has been found in the three kinds of crystals. Crystal data of the superlattice are as follows: orthorhombic, P
b
n21 (No. 33) or P
b
n
m (No. 62); a=12.267(5), b=22.410(9), c=7.732(6) Å for Ba3.75La9.5Ti18O54; a=12.189(3), b=22.319(6), c=7.677(4) Å for Ba3.75Nd9.5Ti18O54; a=12.142(4), b=22.300(6), c=7.653(4) Å for Ba3.75Sm9.5Ti18O54. Space group of the fundamental lattice is P
b
a2 (No. 32) or P
b
a
m (No. 55). The dielectric constants, εr, of Ba3.75
R
9.5Ti18O54 (R=Nd and Sm) are in the high range from 78 to 86, and unloaded Q values are in the range of 2400 to 3000. The excellent values of single phase are better than those of BaR
2Ti5O14 composition including secondary phases.
Low-Fire Bismuth-Based Dielectric Ceramics for Microwave Use
Authors: Kagata Hiroshi , Inoue Tatsuya , Junichi Kato Junichi Kato , Ichirou Kameyama Ichirou Kameyama
Published: February 2005

We have investigated dielectric properties of several bismuth-based ceramics at microwave frequencies. BiNbO4 ceramics containing CuO and V2O5, had a high Q value of Q=4260 (at 4.3 GHz), ε=43, and τf=+38 ppm/°C. In the Bi2O3-CaO-Nb2O5 system, Bi18Ca8Nb12O65 composition had a high dielectric constant of ε=59, Q=610 (at 3.7 GHz), and τf=+24 ppm/°C. The crystal structure of this composition is considered to be an ordered structure based on the body center tetragonal cell (a=0.377, c=0.542 nm). Furthermore, by substituting Zn for Ca, ε increased and τf changed to negative values. In the composition of 45.75BiO3/2-21.75(Ca0.725Zn0.275)O-32.5NbO5/2, excellent properties of ε=79, Q=360 (at 3.3 GHz), and τf=+1 ppm/°C were obtained. As all the above ceramics can be sintered below 950°C, they are applicable to multilayer microwave devices with Ag inner conductors.
Dielectric Properties of Two-Phase Mixture Ceramics Composed of Rutile and Its Compounds
Authors: Haga Kiyoshi , Ishii Tsuyoshi , Jin-ichi Mashiyama Jin-ichi Mashiyama , Takuro Ikeda Takuro Ikeda
Published: February 2005

Dielectric properties of two-phase mixture systems including rutile (TiO2) have been investigated. One of its binary compounds-MnTiO3, ZnTiO3, PbTiO3 and Al2TiO5-was chosen as the second component. Dielectric constants εr and their temperature coefficients τe were first examined at 1 MHz. Dielectric properties in the microwave frequency region were measured in the TE011 mode of a cylindrical specimen. The temperature coefficient of resonant frequency, τf, of MnTiO3 was negative, and a zero coefficient was found at an intermediate composition x=0.13 in the (1-x) MnTiO3-xTiO2 system. In the PbTiO3-TiO2 system, zero τe composition was confirmed at low frequencies, but composition modification trials aiming to make microwave dielectric measurements possible were unsuccessful throughout the entire system.
Development of a High-Q Multilayer Ceramic Resonator
Authors: Shimoda Hideaki , Ishitobi Norimasa , Kawamura Keizou , Kobayashi Makoto
Published: February 2005

It has been discovered that multilayer ceramic resonators, manufactured by a cofiring method at a temperature above the melting point of the inner conductor, have an improved Q-factor. The increase in Q-factor enabled the realization of an S-band multilayer low-loss bandpass filter (BPF). In this paper the insertion loss of the cofired BPFs is examined, and a relationship between firing temperature and Q-factor is established.
Generation of Phase Conjugate Wave Using LiNbO3:Fe and Application to Optical Associative Memory
Authors: Chen Zhiming , Tadashi Kasamatsu Tadashi Kasamatsu , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

Experimental results are presented for a phase conjugate wave generation using an iron-doped lithium niobate single crystal by the degenerate four-wave mixing method. More than 300% reflection efficiency is achieved, and it is almost independent of the total incident optical intensity. The generator is then applied as a phase conjugate mirror to an all-optical associative holographic memory to reflect and amplify the diffracted beams. The retrieved output image is formed by using partial input illumination.
Optical Activity and Electrogyration Effect of Co3B7O13I and Cu3B7O13Cl*
Authors: Takahashi Nobuko , Tomizawa Masahito , Kobayashi Jinzo
Published: February 2005

Optical gyration studies on Co3B7O13I and Cu3B7O13Cl were conducted by the high accuracy universal polarimeter (HAUP) method. Temperature dependences of the gyration tensor g
12 manifested sharp peaks at improper ferroelectric transition points. The electrogyration coefficient of Co3B7O13I also exhibited a sharp peak at the transition point. Taking our previous work of Fe3B7O13I into account, it was concluded that peculiar temperature dependences of gyration and the electrogyration coefficient are a common nature of ferroelectric boracite crystals.
Optical Study of Pb1-xLax(ZryTiz)1-(x/4)O3
Authors: Ichiki Masaaki , Asahi Toru , Shimasaki Tsuyoshi , Kobayashi Jinzo , Ikawa Hiroyuki
Published: February 2005

Optical properties of La-modified lead zirconate titanate (9/65/35) in the intermediate phase were studied by the HAUP (high accuracy universal polarimeter) method. It was found that this material is optically inactive under electric fields. On the other hand, temperature dependence of the quadratic electrooptic coefficient was measured after careful corrections using the HAUP method.
Optical Properties of Gd2(MoO4)3 Studied by High Accuracy Universal Polarimeter (HAUP) Method*
Authors: Asahi Toru , Higano Michi , Kobayashi Cao Fu-Tian
Published: February 2005

Birefringence Δn
c of the improper ferroelectric Gd2(MoO4)3 was accurately measured by using the HAUP (high accuracy universal polarimeter) method as a function of temperature and electric field. Electric field dependence of Δn
c was found to show unique behaviour in the vicinity of T
c. It is of importance that the linear electrooptic coefficient r
63 changes its sign and manifests a sharp peak in the close vicinity of T
c. This result coincides qualitatively with the result reported by Kobayashi and Miyazaki, but disagrees with other reports.
Optical Activity of LiNH4C4H4O6·H2O*
Authors: Saito Kazuya , Kobayashi Cao Fu-Tian
Published: February 2005

Optical properties of LiNH4C4H4O6·H2O (LAT) were studied by means of a high-accuracy universal polarimeter (HAUP). The temperature dependences of the gyration tensor components were obtained. The elastogyration coefficients were determined. Rotation of the indicatrix takes place only around the b axis in the low-temperature phase. The rotation angle of the gyration surface was found to be three orders of magnitude larger than that of the indicatrix.
Formation of Ferroelectric BaMgF4 Films on GaAs Substrates
Authors: Kouji Aizawa Kouji Aizawa , Hiroshi Ishiwara Hiroshi Ishiwara
Published: February 2005

Optimum conditions to form ferroelectric BaMgF4 films on GaAs substrates are investigated. It has been found in vacuum evaporation of BaMgF4 sources that combination of low-temperature deposition and subsequent high-temperature annealing is effective for forming BaMgF4 films that do not contain BaF2 and MgF2 crystallites. The optimum deposition and annealing temperatures obtained thus far are 300°C and 600°C, respectively. Crystallinity and electrical properties of the optimum films are characterized.
Finite Element Analysis of H-Type Vibratory Gyroscope
Authors: Kudo Subaru , Konno Masashi , Yoshida Sumio Sugawara
Published: February 2005

This paper describes the H-type vibratory gyroscope used as an angular rate sensor. The vibrational displacements of the gyroscope are analyzed by the finite element method, and a new structure of the gyroscope, which can be supported at a zero-displacement point, is clarified. This H-type gyroscope is expected to be an angular rate sensor with a high quality factor and high stability.
Cell Thickness Effects in the Determination of Elastic Constant Ratios by Observing Rayleigh Light Scattered Intensity
Authors: Hall Richard , Miyachi Kouichi , Newton David , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

The effects of the finite scattering volume on the values of elastic constant ratios determined have been studied by computer simulation. The errors in the simulated values of K
1/K
2 and K
3/K
2 are dependent on the position of the starting angle of the scan. The error is greatest for thinner cells (≈7 µm) and in the angular regions where the geometrical factor G
m introduced by de Gennes, or a component of the scattering vector q becomes zero, i.e. for external scattering angles approximately less than 10° and those between approximately 20° and 60°, depending on the scattering geometry used. The approximation introduced by van der Meulen and Zijlstra in defining the orthogonal base system (\hate
1, \hate
2, \hate
3) has also been discussed; it is inappropriate in thin cells to use the scattering vector q instead of the wave vector k

l
of the director fluctuations when determining K
1/K
2.
Optical Characterization of Amorphous PbI2 Films and Their Crystallization
Authors: Kondo Shin-ichi , Mikiya Shiraki Mikiya Shiraki , Tadaaki Saito Tadaaki Saito
Published: February 2005

High-quality amorphous PbI2 films were obtained by quench deposition. They were completely transparent below the absorption edge. The absorption spectra of the films were shown to change reversibly with temperature below 195 K, confirming the stability of the amorphous state. Upon heating at a rate of 0.5 K/min, the films showed a sharp crystallization behavior in a narrow temperature range of about 1.5 K near 198 K.
A Superleaktight Demountable Seal for Low-Temperature Use
Authors: Mamoru Ishizuka Mamoru Ishizuka , Kiichi Amaya Kiichi Amaya
Published: February 2005

We describe a superleaktight demountable seal which can be made with no specialized tools. Reliable results are obtained with vacuum silicon grease as a sealant.
Cathodoluminescence from Epitaxial Diamond Layer Grown by Plasma-Assisted Chemical Vapor Deposition on High-Pressure Synthetic Diamond
Authors: Satoshi Katsumata Satoshi Katsumata
Published: February 2005

Cathodoluminescence (CL) spectra and images of an epitaxial diamond layer grown by microwave plasma-assisted chemical vapor deposition (CVD) on high-pressure synthetic (HP) diamond were measured. The epitaxial layer was grown using carbon monoxide (CO) and hydrogen (H2) on a (111)-oriented HP diamond where lattice planes of (131̄), (010), and (141) came together at one corner. On the (111) and (010) planes, band A centered at 420 nm and 520 nm was dominant. The color centers related to nitrogen (533.2 nm; 2.34 eV, 575.9 nm; 2.16 eV) and silicon (739 nm; 1.68 eV) were observed on the (131̄) and (141) planes. The CL images were also observed.
Correction of Energy Shifts to Form Real Three-Dimensional Images by Microprobe RBS
Authors: Katayama Yoshitomo , Atsushi Kinomura Atsushi Kinomura , Mikio Takai Mikio Takai
Published: February 2005

Data processing for three-dimensional analysis by microprobe Rutherford backscattering (RBS) was studied to form real images of multilayered structures. Bilayered Au stripes on Si were analyzed by a 400 keV He+ microprobe. Unprocessed mapping and tomographic images of the inner Au layer showed wavy shapes due to the energy loss of probe beams in the outer Au layer. A set of 8192 RBS-spectra corresponding to a measured frame of 128×64 points was processed by evaluating amounts of Au and the energy loss in the outer Au layer. The inner Au images were successfully corrected after the processing.