bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study on the Electrical Properties of Amorphous Silicon Thin Films in Light-Induced Crystallization
Authors: Chen Z. M. , Ebihara Kenji , John P. K. , Tong B. Y. , Wong S. K.
Published: November 2005

Amorphous silicon films, prepared by glow discharge, LPCVD and electron beam evaporation, were crystallized by incoherent light from an arc discharge. These samples had a wide range of dark conductivities at room temperature varying from 10-11 to 10-6 (Ω·cm)-1 before crystallization, but after crystallization the values converge to 10-5–10-4 (Ω·cm)-1. It is suggested that grain boundaries resulted in an amorphous-like density-of-state distribution, with a maximum at about 0.30±0.05 eV below the conduction band. It is demonstrated that for doped films crystallization effectively activates the dopants.
Plasma Waves Excited by Modulated Line Sources below the Electron Cyclotron Frequency
Authors: Ohnuma Toshiro , Watanabe Tsuguhiro
Published: November 2005

Spatial investigations of potential fields of plasma waves excited by modulated infinite line sources in an inhomogeneous magneto-plasma are investigated. Distinctive mode patterns are obtained numerically.
Confirmation of Homodyne Detection in Forced Rayleigh Scattering for Determining Diffusion Constants of Liquid Crystals
Authors: Takezoe Hideo , Ichikawa Seiji , Fukuda Atsuo , Kuze Eiichi
Published: November 2005

The binary mass diffusion of methyl red in MBBA is measured by forced Rayleigh scattering. In the analysis, the background signal is found attributable to the incoherently scattered light, contrary to the prevailing assumption that it is the coherent one. Because of the homodyne detection, the resultant diffusion constant is smaller by a factor of two compared with the previous incorrectly analyzed results, although the anisotropy is almost the same, D
||
/D
⊥=1.69.
Mode Behavior Improvement in DFB LDs by Light Phase Control at the Facet
Authors: Matsuoka Takashi , Nagai Haruo , Suzuki Yoshio , Noguchi Yoshio , Wakita Ko-ichi
Published: November 2005

Lasing characteristics of InP/InGaAsP DFB-BH LDs, which show a two longitudinal mode operation on both sides of the stop band in as-fabricated state, have been remarkably improved and made into a single longitudinal mode operation by shifting the light phase about π/4 at the facet. The light phase was shifted by changing the relative position of the cleaved facet and the grating. Ion beam etching and dielectric film coating were successfully applied for this purpose.
Property of Conducting Polypyridazine Film Prepared by Electrochemical Method
Authors: Satoh Masaharu , Kaneto Keiichi , Yoshino Katsumi
Published: November 2005

Polypyridazine films with electrical conductivity as high as 6 S/cm and blue in color have been prepared by the electrochemical oxidation of pyridazine monomer for the first time. Reducing the as-grown film by electrochemical or chemical means, a semiconducting film with optical absorption edge of 1.8 eV and a brown color is obtained.
Influence of H2 Overpressure on the Properties of GaAs Grown by Low-Pressure MOCVD
Authors: Mori Hideki , Takagishi Shigenori
Published: November 2005

The influence of H2 overpressure on the electrical and optical properties of GaAs epitaxial layer grown by the low-pressure MOCVD of TMG/AsH3/H2 system was studied. It was demonstrated that high H2 overpressure was not necessary in the reaction process to reduce carbon contamination for low-pressure MOCVD. The carbon incorporation process in low-pressure MOCVD was discussed briefly.
New Approach to Breakdown Study by Measuring Pre-Breakdown Current in Insulating Materials
Authors: Hikita Masayuki , Tajima Seiji , Kanno Ippei , Sawa Goro , Ieda Masayuki
Published: November 2005

A technique of measuring current prior to breakdown was introduced. The breakdown mechanism was discussed on the basis of results obtained for polythylene (PE) and polymide (PI) by applying dc ramp voltage. At 90°C the pre-breakdown current of PI sharply increased from about 1 msec before breakdown. For PE, the sharp current increase could not be detected till about 100 ns before breakdown, which is the resolution limit of the measuring system. If this sharp increase is due to the temperature rise of the sample, thermal breakdown may be dominant in the case of PI but not of PE.
Performance of Lithium/Polyacetylene Cell
Authors: Shinozaki Kenji , Tomizuka Yukio , Nojiri Akio
Published: November 2005

Cell performance of a lithium/polyacetylene battery was investigated. Specific capacity, energy density, and power density were 0.2 Ah/g, 270 Wh/kg, and 23.7 kW/kg, respectively. Cycle life and self-discharge were also tested. Coulombic efficiency dropped to less than 50% after 20-hour storage and this large self-discharge was found to be a serious defect of the cell.
Random Distribution of Ga and Al Atoms in MBE Grown (Al0.5Ga0.5)As
Authors: Kashihara Yasuharu , Kashiwagura Nobuo , Sakata Makoto , Harada Jimpei , Arii Tatsuo
Published: November 2005

The observation of diffuse scattering due to short-range order (SRO) between Al and Ga atoms in (Al0.5Ga0.5)As which were grown by molecular beam epitaxy, has been made using both electron and X-ray diffraction methods. Only diffuse streaks along the <110> directions were detected, the origin of which must be low frequency transverse acoustic phonons. The absence of SRO diffuse scattering is considered evidence of random distribution of Al and Ga atoms in this substance, consistent with the thermodynamical calculation by Onabe (K. Onabe, Jpn. J. Appl. Phys. 21 (1982) L323).
Tritium Detection Using Electret Dosimeter
Authors: Miki Toshikatsu , Ikeya Motoji , Matsuyama Masao , Watanabe Kuniaki
Published: November 2005

Response of an electret dosimeter for tritium beta-rays has been investigated by examining the charge decrease of polymer electrets by the exposure to tritium-involved air. The electret charge decreases proportionally to the tritium activity and the exposure time with a sensitivity of about 10-18 C/pCi·s, roughly corresponding to the theoretical response. Electret dosimeters can be used for the detection of tritium beta-rays of 10 pCi·h/cm3.
Photo-Induced Chemical Vapor Deposition of SiO2 Film Using Direct Excitation Process by Deuterium Lamp
Authors: Okuyama Masanori , Toyoda Yoshihiko , Hamakawa Yoshihiro
Published: November 2005

An attempt has been made on a low-temperature photo-induced chemical vapor deposition of SiO2 thin films by direct excitation without Hg sensitization under irradiation of a deuterium lamp having high energy photons. The film growth has been confirmed at 84°C and the substrate temperature for a considerably good film quality was above 170°C. The deposition rates and the refractive indices of the films deposited above about 170°C are about 100 Å/min. and 1.44–1.46, respectively. Infrared absorption peaks related with Si–H bonding don't appear in the photo-CVD film deposited above 175°C, but appear in the thermal CVD film deposited at 175°C.
A Molecular and Ion-Beam Epitaxy System for the Growth of III-V Compound Semiconductors Using a Mass-Separated, Low-Energy Group-V Ion Beam
Authors: Shimizu Saburo , Tsukakoshi Osamu , Komiya Souji , Makita Yunosuke
Published: November 2005

A new technique for growing III-V compound semiconductor films has been developed, in which the sticking coefficient of the group V element can be increased by implanting mass-separated, high-purity group-V ions at low energy. The newly-constructed growth system consists of an ordinary MBE system and a UHV low-energy ion-implantation system. The deceleration characteristics of the group V (arsenic and phosphorus) ion beams obtained with this low-energy ion implantation system are described. Single-crystal GaAs films are obtained with this growth method between 220°C and 550°C even with a flux ratio of unity by implanting As+ ions at 100 and 200 eV. The PL spectra at 4.2 K of the non-doped films grown at 450°C or higher show well-defined features due to bound exciton and donor-acceptor pairs. High-quality InP layers are also obtained between 210°C and 420°C even with a flux ratio of unity by implanting P+ ions at 100 and 200 eV. These results indicate that the controllability of the group V element in MBE can be greatly improved by implanting mass-separated, high-purity group-V ions at low energy.
Mössbauer Study of Fe-Ti Alloys Formed at Interfaces between Fe and Ti Thin Films
Authors: Harada Hisamochi , Ishibe Shoichi , Konishi Ryōsuke , Sasakura Hiroshi
Published: November 2005

The Mössbauer spectra of Ti films evaporated on Fe substrates (Ti/Fe) and on Ti substrates (Fe/Ti) were measured after heat treatment following the evaporation. The spectra were composed of a singlet, a doublet and the familiar bcc-Fe sextet. The singlet was found to be due to crystalline FeTi, whereas the doublet is attributed to crystalline Fe2Ti in both Ti/Fe and Fe/Ti films annealed at 1000°C and 700∼1000°C. However, in the Ti/Fe films annealed at 700°C, the doublet is ascribed to amorphous Fe
x
Ti1-x
. The relative amounts of FeTi and Fe2Ti suggest that Fe atoms diffuse into the Ti substrates in the Fe/Ti films, while Ti atoms diffuse into the Fe substrates in the Ti/Fe films during annealing.
Secondary Electron Measurement with Auger Electron Microprobe. I. Calibration of the CMA in the Low-Energy Region
Authors: Ogoh Ikuo , Shimizu Ryuichi , Hashimoto Hatsujiro
Published: November 2005

The characteristics of the cylindrical mirror analyzer (CMA) attached to a commercial-type scanning Auger electron microprobe, JAMP-3, were examined for its possible use in monitoring the variation of surface properties through the measurement of the energy distribution of secondary electrons, the N
s(E)-spectrum. For this purpose, a special compact electron gun, small enough to be attached inside a sample holder, was made to calibrate the energy scale of the CMA, and a special arrangement for sample setting was devised to measure the N
s(E)-spectra. This arrangement enables the variation of surface potential to be detected throught the shift of the cut-off point of the N
s(E)-spectrum with as good accuracy as can be obtained by an ESCA-system.
Reflection of keV Light Particles from Random Solids by Modified Single-Collision Model
Authors: Kawatoh Eizoh , Shimizu Ryuichi , Fujita Junji
Published: November 2005

By introducing into the single-collision model a flux-attenuation factor both in the incoming flux and in the outgoing flux, together with a reduced particle energy, we have derived more comprehensive analytical expressions for the number and energy reflection coefficients for all incident-target-atom combinations, leading to a simple explicit representation of the reflection flux under certain approximations. This gives the general qualitative tendency of the light-particle reflection, while a more quantative knowledge should be obtained from computer simulations or analytical approaches including numerical calculation for multiple collisions.
Capacitor Materials with Low Sintering Temperature and Good Dielectric Properties
Authors: Tawfik A. , El-Ati M. I. Abd
Published: November 2005

The system 0.7 Pb(Fe1/2Nb1/2)O3-0.3 Pb(Fe2/3W1/3)O3 modified with aluminium (Al) and Pb(Zn1/3Nb2/3)O3 is used in the manufacture of high-quality materials for ceramic capacitors. The sintering temperature is reduced to 820 by adding Al, and samples show a higher dielectric constant than those of the system doped with Pb(Zn1/3Nb2/3). The results are explained in terms of the role of lattice defects and the effect of the relative size variations of ions in the modified crystal lattice.
Improvement of Radiation Resistance of Pure Silica Core Fibers by Hydrogen Treatment
Authors: Nagasawa Kaya , Hoshi Yutaka , Ohki Yoshimichi , Yahagi Kichinosuke
Published: November 2005

A pure silica core fiber with glass cladding is known to produce larger absorption in the visible wavelength region under γ-ray irradiation than a similar fiber with silicone cladding. This absorption is a serious problem, especially in image-guiding fibers used in radiation environments such as in nuclear power plants. The absorption is attributed to the formation of defect centers such as non-bridging oxygen hole centers and E' centers induced by bond scission. A new and simple method of hydrogen treatment to improve the radiation resistance of an optical fiber with a pure silica core has been proposed. Post-treatment by this method can significantly reduce existing radiation-induced absorption, while preliminary treatment can suppress the increase of the radiation-induced absorption.
Quantitative Surface Atomic Structure Analysis by Low-Energy Ion Scattering Spectroscopy (ISS)
Authors: Aono Masakazu , Souda Ryutaro
Published: November 2005

Surface atomic structure analysis by low-energy ion scattering spectroscopy (ISS) is reviewed, with particular emphasis on quantitative surface atomic structure analysis by ISS. The important differences between ISS and Rutherford backscattering spectroscopy (RBS), some basic characteristics of ISS, a special type of ISS called impact-collision ion scattering spectroscopy (ICISS), and the general features of the shadow cone in the energy range of ISS are discussed as a basis for the description of particular examples of ISS studies which follow. The examples are mainly concerned with the analysis of the atomic arrangement, defect structure, thermal vibration, and electron spatial distribution of the (001) and (111) surfaces of TiC.
Recrystallization of Silicon-on-Insulator Structures by Sinusoidally-Scanned Electron Beams
Authors: Ishiwara Hiroshi , Ohyu Kiyonori , Horita Susumu , Furukawa Seijiro
Published: November 2005

This paper describes the recrystallization by an electron beam of Si films deposited on SiO2/Si structures. To achieve pseudo-line-shaped heating, a spot beam was scanned along a line at frequencies of up to 10 kHz. It is predicted theoretically that the temperature profile along the line can be controlled by the scanning waveform and that a concave molten zone edge is obtained wih a sinusoidal scan. It was found experimentally that the recrystallization conditions required for forming a large single-crystal area with a flat surface are rather restricted in the sinusoidal-scan method, since the Si films are broken up or deformed by the temperature gradient along the line. It was also found that overlapping scans of the pseudo-line-shaped beam are effective in increasing the single-crystal area. A nearly single-crystalline Si film of 300×200 µm2 was produced on an SiO2/Si structure by overlapping scans.
Properties of Hydro-Fluorinated Amorphous Silicon-Carbide Produced by Intermediate Species SiF2
Authors: Uesugi Takashi , Ihara Hisanori , Matsumura Hideki
Published: November 2005

A new type of hydro-fluorinated amorphous silicon-carbide (a-SiC:F:H) film was produced by the glow-discharge decomposition of intermediate-species SiF2, H2 and CF4 gas mixture or SiF2, H2 and CH4 gas mixture. Boron and phosphorus were added to this a-SiC:F:H by mixing B2H6 and PH3 with the gas mixtures. The optical, structural and electrical properties of the a-SiC:F:H films were studied experimentally, and it was found that the optical band gap of a-SiC:F:H can be increased up to 2.2 eV by increasing the carbon content without apparent degradation of film properties such as the photo-conductivity or photo-sensitivity, and also that the conductivity of impurity-doped a-SiC:F:H can be increased above that of the similar hydrogenated amorphous silicon-carbide (a-SiC:H) produced from a CH4 and SiH4 gas mixture.
The Effect of Back-Reflection on the Performances of N2-Lasers
Authors: Masilamani V. , Docchio F. , Magni V.
Published: November 2005

The increase in power and brightness of Nitrogen laser beams by using back reflecting mirrors is discussed for the two cases of low pressure and atmospheric pressure N2-lasers. In both cases, the proper choice of the position of the back reflector led to a brightness enhancement by more than one order of magnitude.
This improvement, on the atmospheric pressure laser, made it suitable for pumping high repetition rate distributed feedback dye lasers.
A New Method (the Three-Point Method) of Determining Transient Time Constants and its Application to DLTS
Authors: Hasegawa Fumio
Published: November 2005

Many physical phenomena have a transient which can be expressed as an exponential change of parameters. A new method of determining the transient time constant is proposed and is applied to the measurement of the emission rates of a deep level in GaAs. The time constant (emission rate) and magnitude of the capacitance change (trap density) can be simply obtained from the ratio of the capacitance change between three points with the same intervals.
Interfaces as a Field for Arranging Organic Molecules
Authors: Miyano Kenjiro
Published: November 2005

A review is given of some remarkable interfacial phenomena exhibited by materials such as liquid crystals and amphiphilic molecules. Emphasis is placed on recent evidence of peculiar molecular ordering at the interface not found in the bulk. The nature of the ordering is often quite unexpected and sometimes contradicts our intuitive feelings. Because the common feature of the molecular ordering is high density and a high degree of orientational and in some cases positional order, it is proposed that the interfaces be used as a field for molecular manipulation in the preparation of new materials.
New Room-Temperature Ferroelectric Liquid Crystals –Material Constants and Electro-Optic Properties–
Authors: Kondo Katsumi , Era Susumu , Isogai Masato , Mukoh Akio
Published: November 2005

A binary ferroelectric liquid-crystal mixture having both room-temperature ferroelectricity and a large spontaneous polarization has been developed. The temperature range is from 20°C to 34°C. The spontaneous polarization is almost the same value, 4 nC/cm2, as that in DOBAMBC. Five material constants for the mixture; the transition temperature, spontaneous polarization, helical pitch, tilt angle and birefringence, are reported. A guest-host-type device was fabricated using the mixture, and some potential problems in the application of the materials to electro-optical switching devices are pointed out on the basis of the optical properties of this device.
Macroscopic Axial Dopant Distribution in Czochralski Silicon Crystals Grown in a Vertical Magnetic Field
Authors: Hirata Hiroshi , Inoue Naohisa
Published: November 2005

Phosphorus and aluminum-doped silicon crystals 3 inches in diameter are grown by the Czochralski method in a vertical magnetic field of 2500 Oe. It is shown that the macroscopic axial dopant distribution is remarkably homogenized by the magnetic field. Melt stirring under the magnetic field is apparently only partial, and the effective segregation coefficients for phosphorus and aluminum are 0.77 and 0.0082, respectively, several times larger than the respective equilibrium values. The diffusion layer thickness is accurately determined to be as thick as 5 ∼6 mm in the strong vertical magnetic field, confirming our previous result obtained by microscopic analysis. Transients are found in the dopant concentration near the seed end of the crystal, giving strong evidence for a thick diffusion layer.
On the Epitaxial Relationships of TiSi2 on Silicon
Authors: Nipoti R. , Armigliato A.
Published: November 2005

A structural study on the epitaxial relationships of TiSi2 on <100 > silicon has been carried out by transmission electron microscopy. Metallic films, heat treated at high temperatures (750 and 850°C), react with silicon forming the orthorhombic TiSi2 phase with quite large grains, up to 5 µm in diameter, which present some orientation relationships with the crystalline bulk. They are [011]TiSi2
//[001]Si, [110]TiSi2
//[001]Si, [010]TiSi2
//[001]Si.
Structural Analysis of the NiSi2/(111)Si Interface by the X-Ray Standing-Wave Method
Authors: Akimoto Koichi , Ishikawa Tetsuya , Takahashi Toshi , Kikuta Seishi
Published: November 2005

The atomic structure of the interface between an epitaxial NiSi2 film without a 180°-rotated twin-crystal region and an Si(111) substrate was investigated by the X-ray standing-wave method using synchrotron radiation. The angular yield of Ni Kα fluorescent X-rays was measured around the Bragg angle of both 111 and 111̄ reflections of the Si substrate. By fitting the profile of the experimental yield curves with that of the calculated ones, the atomic structure of the interface was determined and the lattice distortion of NiSi2 films investigated.
Photo-Deep-Level Fourier Spectroscopy in Semi-Insulating Bulk Materials
Authors: Ikeda Kousuke , Takaoka Hidetoshi , Ishii Yoshikazu
Published: November 2005

A new technique called photo-deep-level Fourier spectroscopy (photo-DLFS) for evaluating deep levels in semi-in-sulating materials is proposed. It is presented with a frequency space analysis that makes it possible to analyze the deep-level parameters, without correction for the complicated temperature dependence in the current-transient equation, using numerical calculation of the Fourier coefficients taken from the Fourier transforms of the transient current values. Seven deep levels were detected in semi-insulating undoped LEC GaAs crystals using this method. Also, a comparison is made with the photo-DLTS method.
Experiments on a Point-Contact Josephson Mixer at 469 µm
Authors: Kobayashi Masayoshi , Ohara Shinji , Katsuno Akira , Sakai Kiyomi , Ogawa Hideo
Published: November 2005

An Nb point-contact Josephson mixer with a corner reflector behind the Nb 4-wavelength wire antenna was constructed, and experiments were carried out at 469 µm (693 GHz). A 10 dB improvement in coupling efficiency was obtained by using the reflector. An SSB (single-side-band) mixer noise temperature of 1660 K was obtained, and the conversion efficiency of the mixer was -35.7 dB in the 9th harmonic mixing between 71 GHz LO and 693 GHz signal.
Evaluation of Si Thin Films by Photothermal Deflection Spectroscopy (PDS)
Authors: Hata Tomonobu , Hatsuda Tsuguyasu , Komatsu Tohru
Published: November 2005

This paper reports a theoretical and experimental study of a photothermal deflection spectroscopy (PDS) method for thin films. Multiple reflection of the incident light is taken into account in the theoretical analysis, using a simplified one-dimensional model. An experiment was performed to estimate the optical absorption coefficients α of a-Si:H and µc-Si:H films. It is possible to obtain the difference in α between these Si films very accurately even for αL<10-2. Thus PDS is very effective for measuring the small absorption coefficients of thin films.
Measurement of the Dielectric Relaxation of Ferroelectric Substances by Lumped-Capacitor Time-Domain Spectroscopy
Authors: Baba Kenzo , Yamakami Tsutomu , Fujimura Tadao
Published: November 2005

The dielectric relaxation of ferroelectric CsH2PO4 was measured by lumped-capacitor time-domain spectroscopy in both the paraelectric and ferroelectric phases in the temperature range from 144.8 K to 182.2 K. The time-domain responses from the sample were subjected to time-domain and frequency-domain analyses and the dielectric relaxation parameters were calculated. The results agree with those of earlier studies using frequency-domain measuring methods.
Prediction of Treeing Breakdown from Pulse Height of Partial Discharge on Voltage-Phase Angle
Authors: Okamoto Tatsuki , Tanaka Toshikatsu
Published: November 2005

This paper describes the change in the partial discharge (PD) characteristics due to the growth of electrical trees in insulating materials under the application of an AC voltage. An electrical tree consists of branch-like dielectric breakdown paths. Investigation of a number of characteristic PD parameters shows that the φ-q distribution profile has a good correlation with tree growth. The φ-q distribution expresses the average pulse height as a function of the AC voltage-phase angle. The distribution indicates a common profile for trees growing in both epoxy resin and polyethylene. Tree growth in these materials can thus be detected by monitoring the profile of the φ-q distribution, and the final breakdown can be predicted from the tree growth.
Highly Oriented ZnO Films Prepared by MOCVD from Diethylzinc and Alcohols
Authors: Oda Shunri , Tokunaga Hiroyuki , Kitajima Nobuyuki , Hanna Jun-ichi , Shimizu Isamu , Kokado Hiroshi
Published: November 2005

Alcohols have been shown to be useful as oxidizing agents of diethylzinc for the growth of ZnO films by MOCVD. C-axis oriented ZnO films have been deposited on glass substrates at 300°C. The problem of a premature reaction, which is observed between diethylzinc and oxygen or water vapor, is shown to be overcome when alcohols are used instead. The formation, stability and decomposition of the precursor of MOCVD, e.g., adducts, are discussed on the basis of a mass-spectroscopy analysis.
Solid Breakdown Process from Viewpoint of Nature of Pre-Breakdown Current in Polymeric Insulating Materials
Authors: Hikita Masayuki , Kanno Ippei , Sawa Goro , Ieda Masayuki
Published: November 2005

Solid breakdown process was discussed on the basis of the experimental results on the electrical conduction just prior to breakdown for various polymeric insulating materials. For polyamideimide (PAI) and non-stretched polyvinylidene fluoride (PVDF), the pre-breakdown current sharply increased from an order of 1 µs before breakdown. For polytheylene terephthalate (PET) and stretched PVDF, a sharp current increase could not be detected till about 100 ns, which was a limit of time resolution. Assuming that this sharp current increase is caused by the increase of filamentary current due to the temperature rise of a small spot, we discussed the maximum radius of the filament. It was concluded that for leading to filamentary thermal breakdown the radius of the filament should be less than about 3.5 µm for PAI and non-stretched PVDF, and 1.3 µm for stretched PVDF and 3000 Å for PET.
Effect of Implantation-Induced Anisotropy on Magnetization Distributions in Garnet Films
Authors: Shiomi Shigeru , Masuda Morio
Published: November 2005

The magnetization distributions in ion-implanted garnet films are investigated through numerical computation of the equation of motion for the magnetization vectors. Taking into consideration the different distributions of the implantation-induced anisotropy, we calculate the polar and azimuthal angles of the magnetization vectors as a function of depth. It is found that the polar angle varies in considerable accordance with the variation of the perpendicular anisotropy. On the other hand, the variation of the azimuthal angle is rather complicated. It is shown that this is due to the influence of cubic magnetocrystalline anisotropy.
Effect of an InP Buffer Layer on Photoluminescence Efficiency of an InGaAsP Layer
Authors: Komiya Satoshi , Umebu Itsuo
Published: November 2005

The photoluminescence intensity of the quaternary layer only in the InP/InGaAsP/InP DH structure is measured as a function of the thickness of the InP buffer layer and the excitation power density. The photoluminescence efficiency drops sharply when the buffer layer thickness is reduced to less than 0.3 µm. A buffer layer more than 0.5 µm thick is required for sufficient photoluminescence efficiency at low excitation. The degradation rate recovers gradually at high excitation in all cases. The radiative recombination efficiency of the quaternary layer is analyzed from the dependence of the photoluminescence intensity on the excitation power. In a DH wafer with no buffer layer, the effective non-radiative recombination life-time is estimated as 2×10-9 s.
Absorption Losses of Low Loss Plastic Optical Fibers
Authors: Kaino Toshikuni
Published: November 2005

Absorption loss factors such as the high harmonics of molecular vibrational absorption and the electronic transitional absorption of plastic optical fibers are analyzed and it is quantitatively revealed that the high harmonics of the CH vibrational absorption of core material are the most significant constituents causing the loss in PMMA-core fibers. OH vibrational absorption due to contained water, on the other hand, has the most effect on loss in perdeuterated PMMA (P(MMA-d8)) core fibers. Visible wavelengths (570 and 650 nm) are preferable for optical signal transmission for PMMA- or P(MMA-d8)-core fibers.
Nanosecond Stroboscopic Electron Spectroscopy for Observation of Nuclear Excitation by Electron Transition (NEET) in 197Au
Authors: Fujioka Hiromu , Ura Katsumi
Published: November 2005

Electron transitions to inner atomic shells release their excess energies in the form of X-rays or Auger electrons. In addition to these two usual processes, a third mechanism called nuclear excitation by electron transition (NEET) can participate in the de-excitation process of atomic inner-shell ionization, if the NEET conditions, in which the nuclear and electronic transitions have almost equal transition energies and a common multipolarity, are satisfied. To observe NEET in 197Au, which would emit 63 keV internal conversion electrons with a half-life of 1.9 ns as a consequence of the NEET process, a specially designed stroboscopic electron spectrometer system was developed. The system allows us to observe the time spectrum of conversion electrons with a time resolution of subnanoseconds.
Multi-Gate Photon Counter for Studying Temporal Correlation of Spectral Line Intensity and Discharge Current
Authors: Kimura Muneyasu
Published: November 2005

A sensitive, accurate multi-gate photon counting system for the spectral measurement of weak lines emitted from Ne atoms and ions excited by square-wave voltage pulses in hollow-cathode discharge tubes has been developed. Features of the system are, 1) improvement of the temporal properties of the high voltage pulse generator, 2) regulation of the whole system by a single standard clock time, permitting synchronous operation, 3) increase of the number of pairs of sampling gates and photon counters to ten, improving the efficiency of weak intensity measurement, 4) increase of the precision of the time-resolving power to ±0.5 µs. The temporal change of intensity of several neutral and ionic lines of Ne as a function of the intensity of the discharge current are presented for the initial transient state.
Two-Dimensional Numerical Analysis of Amorphous-Silicon Field-Effect Transistors
Authors: Hirose Nobumitsu , Uchida Yasutaka , Matsumura Masakiyo
Published: November 2005

A two-dimensional transistor model for short-channel amorphous-silicon (a-Si) field-effect transistors has been developed, taking the localized states in a-Si into account, and the basic characteristics of the transistors have been clarified by numerical computation. The mechanisms determining the short-channel transistor performance have been discussed. It is predicted that a 1 µm transistor with satisfactory performance can be fabricated by thinning the active a-Si region to 20 nm.
Neutron Diffraction from a LiNbO3 Crystal with Excited Surface Acoustic Waves
Authors: Takahashi Toshio , Granzer Erwin , Tomimitsu Hiroshi , Kikuta Seishi , Doi Kenji
Published: November 2005

The rocking curves of neutron Bragg reflections from LiNbO3 crystals were measured with and without acoustic waves excited on their surfaces. Travelling waves and standing waves were excited on the LiNbO3 crystals, and symmetric Bragg-case diffractions of the (030) planes were used. Enhancement of the integrated intensity and increase in the peak height were observed. A qualitative interpretation based on the diffraction of distorted crystals is given.
X-Ray Diffraction Studies of Subtransition in Dipalmitoylphosphatidylcholine
Authors: Akiyama Morio
Published: November 2005

The kinetics of the structural change accompanying subtransition in hydrated dipalmitoylphosphatidylcholine has been studied using X-ray diffraction methods. Following incubation at 1.5°C, the Lβ' phase transformed to a more stable phase. The repeat period of the lamellar structure and the interchain spacing shifted continuously from 62.5 Å and 4.18 Å to 58.9 Å and 4.38 Å with time. At no periods of transformation could the coexistence of the Lβ' phase and the more stable phase be observed. These observations suggest that the transformation does not follow a two-state transition with first-order kinetics.
Coalescence Growth Mechanism of Smoke Particles
Authors: Kaito Chihiro
Published: November 2005

Measurements of size increment for Ag smoke particles against the temperature has shown that the coalescence of Ag smokes takes place at 270°C. High resolution electron microscopy of the boundary between connected particles has shown that the particles are connected in either a (111) twin relation or (100) parallel orientation. The parallel orientationis predominantly seen in the temperature ranges of 270∼400°C. By using the Lindeman melting formula and reported Debye temperature, it is shown that the coalescence phenomena in smoke particles can be explained by taking into account the two processes with the temperature, i.e. the liquid-like coalescence and surface melting coalescence.
The Origin of Dark Region in LPE GaP Associating with Macrostep Riser
Authors: Pak Kangsa , Nishinaga Tatau , Tanbo Toshiharu , Fukuhara Hiroaki , Nakamura Tetsuro , Yasuda Yukio
Published: November 2005

The origin of the dark region in LPE grown GaP crystals associated with macrostep is investigated by observation of photoluminescence (PL) image and spatially resolved photolumenescence (SRPL) spectroscopy. PL image from the cleaved surface of undoped, N, S, and Zn doped layers showed that the dark region appeared only when nitrogen was doped irrespective of simultaneous doping of S or Zn. The result of SRPL measurement showed that the concentration of N was lower in the dark region compared with the bright region. This could be explained by the difference of the step velocity on the riser and the tread of the macrostep.
Vapour Growth of Nb3Se4 Crystals
Authors: Nakada Ichiroh , Ishihara Yutaka
Published: November 2005

Single crystals of Nb3Se4 were grown by vapour growth technique with chemical transport in the temperature region of about 1000°C, with iodine transporter. A batch of tiny needle-like or fibre crystals about 5 mm in length was found to grow after three to four weeks. Some of the crystals grew to a size of 0.3×0.3×5 mm3 and had a pseudo-hexagonal crystal habit. Observation by optical microscope revealed fine step structures on the surfaces of the crystals, suggesting that the crystals had grown by the surface diffusion process characteristic of the vapour transport growth.
An Energy Resolution Formula of a Three Plane Grids Retarding Field Energy Analyzer
Authors: Sakai Yoshiyuki , Katsumata Ituso
Published: November 2005

The energy resolution of a retarding field energy analyzer, composed of a collector and three metal wire woven plane grids separated by the same distance, is investigated both theoretically and experimentally. The resolution is presented in terms of the diameter of the wire, the spacing between wires and the distance between grids. In the test experiment, thermionically generated Cs+ ion beams are used together with 5 sizes of meshes with different grid separations. Good agreement is achieved between the theory and the experimental results.
Reduction of Background Luminance Generated in the Output Screen of X-Ray Image Intensifier Tubes
Authors: Tsuda Motohisa , Kimura Yutaro
Published: November 2005

Background luminance of several origins introduced into an X-ray image intensifier tube deteriorates the contrast of its output image. The output screen, which consists of a phosphor layer usually prepared on a transparent substrate, generates influential background luminance in the X-ray image intensifier tube.
A theoretical and experimental study on how reduce the background luminance of the output screen by increasing the thickness of the substrate is presented. In evaluating the effect of the background luminance, we calculated and measured the contrast ratio usually used as a characteristic index of the image intensifier tube.
The theory and results from the experimental image intensifier tubes show good agreement.
This method of background luminance reduction is not only more economical but also superior to the other methods utilizing dark substrates or optical fiber plates.
Oscillation of a Drop Hanging from a Tube
Authors: Watanabe Yoshio
Published: November 2005

Oscillation of a drop hanging from a tube is investigated both theoretically and experimentally. The period of oscillation is obtained based on the assumption that the apparent specific weight, which is defined as the sum of the actual force and the inertial force per unit volume minus the force due to the surface tension, is unifrom at each time in the drop. The results agree well with experimental values obtained by high-speed photography.
Relaxation Processes Associated with Crystallization and Glass Transition in Amorphous 5PbO·3GeO2
Authors: Maeda Masaki
Published: November 2005

Relaxation processes associated with crystallization and glass transition in amorphous 5PbO·3GeO2 have been investigated. The glass transition temperature and the crystallization temperature are found to depend on the heating rate and the annealing time. Elastic properties of amorphous ribbons have been measured varying the temperature and under various annealing conditions. The temperature dependence of structural relaxation time has been determined by measuring the sound velocity. The results are phenomenologically discussed based on a thermodynamical energy scheme.
Deformation of Needle in the High Temperature Gas behind Detonation Wave
Authors: Tsuboi Takao , Kamei Masaaki , Teranaka Yoshihiko , Sakaki Seiji , Mori Shinzo
Published: November 2005

Deformation of needle-points in burning gas behind H2-O2 and natural gas-O2 detonation has been investigated experimentally. Three typical cases of deformation are observed: (1) melting of the needle-point; (2) burning of the needle; and (3) breaking of the needle. The kind of deformation depends on the setting place of the needle in the detonation tube as well as on the mixture ratio.
Photo-Induced Current Transient Spectroscopy in High-Resistivity Bulk Material. III. Scanning-PICTS System for Imaging Spatial Distributions of Deep-Traps in Semi-Insulating GaAs Wafer
Authors: Yoshie Osamu , Kamihara Mitsuo
Published: November 2005

A scanning-PICTS system for imaging two-dimensional distributions of deep-traps in a semi-insulating GaAs wafer is presented. The utility of this system is demonstrated using a LEC-grown undoped semi-insulating GaAs wafer which exhibits a W-shaped dislocation-density variation along the wafer diameter. It has been found that the density of 0.14 eV electron-trap in the wafer exhibits a distinct inverse-W-shaped variation along the diameter and that this trap is closely correlated with the dislocation. The densities of 0.31 eV and 0.55 eV electron-traps have been found to exhibit a very “in-distinct” inverse-W-shaped variation along the diameter, and that the traps are correlated slightly with the dislocations. Thus the scanning-PICTS technique is a very powerful tool for observing one- and two-dimensional distributions of traps in a wafer of semi-insulating material.
Effect of Thermal Aging on Breakdown Strength of Polyethylene
Authors: Katakai Shoshi , Yahagi Kichinosuke
Published: November 2005

Effect of thermal aging on breakdown strength of low-density polyethylene has been investigated with fixed electrodes. Thermal aging of polyethylene induces oxidation and rearrangement of molecular chains which cause an increase of its crystallinity and a decrease in the long period. In the initial stages of thermal aging, the amorphous parts grow strained with an increase in the crystallinity, and oxidation products introduced in the crystalline surface regions may act as deep traps for electronic carriers which in turn cause an increase in the breakdown strength at room temperature. In the advanced stages of thermal aging and in the high temperature range where crystalline melts, carbonyl groups in amorphous parts due to oxidation may become active and act as hopping sites for accelerated electrons. Therefore, the electronic conductivity increases and the breakdown strength decreases.
Electric Field Distributions in Askarel Subjected to DC Stress between Plane Parallel Electrodes
Authors: Eto Mitsuyoshi
Published: November 2005

The results of electric field measurements in a mixture of pentachlorobiphenyl and trichlorobenzene using the Kerr effect are presented. Field non-uniformity results from the accumulation of heterocharges at both electrodes. The effects of dividing the interelectrode region with solid spacers and variation of electrode material and temperature have been investigated.
Rotational Energy Transfer in A2Σv'=0 State of OH in Flame: On the Use of Laser-Induced Fluorescence Spectrum for Flame Temperature Measurement
Authors: Furuya Yoshiyuki , Yamamoto Manabu , Takubo Yoshitaka
Published: November 2005

Experiment and simulation of the population distribution over the rotational levels of OH (A2Σ, v'=0) in an atmospheric pressure flame, following laser excitation of one of these rotational levels, are described. The measured distribution can be quantitatively understood on the basis of the energy-transfer rates reported previously. A method for determining flame temperatures from the laser-induced fluorescence spectra is discussed.
Precipitation of γ-Fe2O3 from Ultrahigh Temperature Plasma
Authors: Kagawa Masahiro , Ohta Heishiro , Komatsu Hiroshi , Syono Yasuhiko
Published: November 2005

Precipitation of ultrafine iron oxides from an argon inductively coupled plasma of ultrahigh temperature (ICP) has been investigated. Aqueous solutions of iron salts and solid α-Fe2O3 are introduced into ICP. The iron oxides are precipitated in two types of collectors, a water-cooled tube with an open end (collector A) and a tube with a closed end (collector B). The iron oxides are γ-Fe2O3, regardless of the mother reactants and the type of the collectors. However, particle morphology ofγ-Fe2O3, is found to be largely dependent upon the collectors. The particles in the collector (A) are ultrafine (≃10 nm in size) and show no clear habit, owing to rapid quenching. In the collector (B), however, relatively large bi-crystals and polyhedra (10–70 nm) are formed, apparently through the coalescence growth enhanced by the convectional gas flow in the collector.
Time Domain Analyses for Various Types of Dielectric Relaxations by a Lumped Capacitor Method
Authors: Baba Kenzo , Fujimura Tadao
Published: November 2005

Several formulas are proposed for analyzing by a lumped capacitor method time domain responses to an incident wave of finite transient time for different types of dielectric relaxations with dc electric conductivities. The experimental problems associated with the transient behavior of the responses and the measurements of the multiple relaxation type dielectric relaxations are discussed.
Theoretical Response of Electret Dosimeter to Ionizing Radiation
Authors: Miki Toshikatsu , Ikeya Motoji
Published: November 2005

A theory regarding the response of an electret dosimeter to ionizing radiation was developed for both parallel-plate-type and coaxial-cylinder-type dosimeters. The theoretical analysis was made to include the gas-multiplication mode and the ionization-chamber mode on the basis of theories regarding gaseous electronics and ionization chambers. The experimental response of an electret dosimeter agreed with the theoretical response.
Raman Lineshape Study of Iodine in Solutions by Circular Polarization Difference Raman Spectroscopy
Authors: Yamaguchi Satoshi , Kobinata Shunsuke , Maeda Shiro
Published: November 2005

The circular polarization difference Raman spectra of iodine dissolved in several organic solvents were observed in order to investigate the molecular motion in solution. The Raman bands of iodine measured by the method of difference spectra are distinctly asymmetric in shape in cyclohexane and carbon tetrachloride, and almost completely symmetric in dichloromethane and benzene. In the latter solvents, the reorientational motion of iodine is considered to be a rotational Brownian type. The asymmetry observed in the former solvents has been interpreted as an indication of the weak survival of O, S branches of iodine arising from the free rotation. It has been shown that a quantum mechanical treatment can simulate the observed asymmetry.
High-Field Distribution and Mobility in Semiconductors
Authors: Arora Vijay K.
Published: November 2005

A first-principles theory of carrier distribution in the presence of an electric field of arbitrary strength, which takes into account the quantum-mechanical field-broadening, is described under conditions that the acoustic-phonon scattering is the dominant mechanism of scattering. The general expression of the mobility so obtained reduces to its Ohmic value for vanishing small electric fields, is a quadratic function of electric field in the warm-electron regime, and varies inversely with the electric field at sufficiently high electric fields (hot-electron regime). A saturation current is obtained in the high-field limit, when electron mobility is limited solely by the field-broadening effect; the saturation velocity being comparable to the thermal velocity of an electron. The hot-electron temperature, defined in terms of average energy of an electron, is equal to the lattice temperature in the Ohmic regime, rises quadratically with the increasing electric field in the warm-electron regime, and rises linearly in the hot-electron regime. These results are in agreement with those of experiments on n-Germanium.
Effects of Oxygen Pressure on Optical Absorption of YAG
Authors: Masumoto Toshiaki , Kuwano Yasuhiko
Published: November 2005

The optical absorption of YAG crystals annealed under oxygen partial pressures of between 10-13.8 and 1 atm was measured. The observed dependence of the optical absorption on the oxygen partial pressure during annealing supports a previous model proposed by Mori, in which excitation-induced transient absorption and 310 nm absorption are ascribed to an F+ center and an Fe2+ impurity, respectively. It was observed that the excitation-induced transient absorption was proportional to the 310 nm absorption. This proportionality suggests that the Fe impurity ions are located near the oxygen vacancies. The excitation-induced stable absorption at 600 nm, which appears to cause the absorption loss during cw laser operation, can be minimized by annealing under an oxygen partial pressure of 10-7 atm at 1400°C.
Perpendicular Anisotropy in Bi-Doped Amorphous Ferrimagnetic GdFe, GdCo and GdFeCo Thin Films
Authors: Saiki Koji , Onishi Koji , Inokuchi Seiji , Sakurai Yoshifumi
Published: November 2005

We have studied the effects of Bi-doping on the perpendicular anisotropy in sputtered Gd(Fe1-x
Co
x
) amorphous films. Over the range of 0 ≦x ≦1, the perpendicular anisotropy increases remarkably with the addition of Bi-atoms together with the shift of saturation magnetization toward the transition metal TM dominant magnetically. GdFe films doped with Bi have a perpendicular anisotropy even when prepared under a bias-potential application. The increase of anisotropy by Bi-doping is interpreted neither by the term of a stress nor by a simple shape anisotropy. It is considered that the segregation of non-ferromagnetic GdBi
x
, takes place. The alignment of the TM dominant phase in the region of GdBi
x
would be the origin of a large perpendicular anisotropy.