bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Substrate-Surface Cleaning on Solid Phase Epitaxial Si Films
Authors: Kunii Yasuo , Tabe Michiharu , Sakakibara Yutaka
Published: November 2005

The effects of two substrate-surface cleaning procedures were studied for solid-phase epitaxy of chemical vapor deposited amorphous Si (a-Si) films with respect to crystalline quality. These a-Si films were deposited on Si (100) wafers after surface cleaning by HF-dipping or in-reactor gas etching. The a-Si films were then crystallized by furnace annealing. The film quality was estimated using several techniques, such as etch-pit density measurements. For the samples etched by HF-dipping, the film crystallinity became worse with increasing film thickness owing to a residual oxide layer at the deposited-film/substrate interface. As a result, the electron mobility decreases with increasing deposited film thickness. For in-reactor gas-etched samples, the residual at the interface was negligible, and the crystallinity of a SPE film was as good as that of bulk Si.
X-Ray K-Absorption Edge Analysis of Cobalt in Some Cobalt Complexes
Authors: Khadikar Padmakar V. , Pandharkar Sadhana P.
Published: November 2005

The X-ray K-absorption spectra of cobalt in some cobalt complexes have been investigated using a 40 cm Cauchois type bent crystal transmission spectrograph. The results have been explained on the basis of the molecular orbital theory and information regarding the nature of bonding and coordination has been deduced. Various X-ray K-absorption parameters are obtained and compared with optical parameters. A linear correlation has been observed among coordination stoichiometry, edge shift and effective nuclear charge. The data subjected to the method of least squares indicated that the correlation is genuine.
Stuffing of Noble Metals into Anodized Porous Silicon by Direct Evaporation
Authors: Ito Toshimichi , Hiraki Akio
Published: November 2005

Silver and Gold were evaporated onto porous Si prepared on a Si(100) substrate (2–6 ohm·cm) by means of an anodic reaction in hydrofluoric acid electrolyte (HF:H2O:C2H5OH=1:1:2) with a suitable anodic current (20–40 mA/cm2). Under a ultra-high vacuum condition, metal up to ∼ 100 Å thick was deposited over as-prepared, as-sputtered and as-annealed porous films at room and elevated temperatures, and the stuffing of the deposited metal atoms was examined by means of AES and ELS techniques. After room-temperature deposition, the distribution of gold, a reactive metal with Si, had much wider depth profiles than that of a Au/bulk Si system, except for as-prepared specimens. In the case of Ag, a much less reactive metal than Au, the same tendency was observed. These results are discussed with regards to atomic diffusions through pores and to the pore size distribution of a porous substrate with different treatments.
Rectification Properties of Asymmetrical Superlattices
Authors: Aishima Asuo , Fukushima Yoshifumi
Published: November 2005

A rectifying superlattice which can be used for detecting THz waves is proposed. The device is created by using an effective-mass superlattice in which the superlattice cycle is gradually changed. The operating principle is based on the fact that the quantum mechanical transmission coefficient with asymmetrical geometry is asymmetrical with respect to the applied voltage. The forward current is several orders in magnitude greater than the reverse current at a relatively low applied voltage. This feature is potentially useful for detecting and mixing small signals at THz frequencies.
Comparison of Lateral Resolution of Fine Stripes Beryllium and Boron Implanted by Focused Ion Beam in Si-Doped AlGaAs/GaAs Multiquantum Wells
Authors: Brillouet Francois , Ishida Koji , Morita Tetsuo , Miyauchi Eizo , Takamori Takeshi , Nakashima Hisao
Published: November 2005

Using impurity controlled Al–Ga intermixing in Si-doped Multi-Quantum Wells (MQW), a highly anisotropic Be diffusion after Focused Ion Beam (FIB) implantation and thermal annealing was measured by Auger Al profiles analysis, with a Be lateral diffusion dependent on the scan speed of ion beam. Then, after the demonstration of Al–Ga intermixing suppression by Boron FIB implantation, an improved lateral pattern resolution was obtained with Boron implantation in Si-doped MQW.
Preparation of Te Films by Hot Wall Epitaxy
Authors: Athwal I. S. , Bedi R. K.
Published: November 2005

Hot wall epitaxy technique has been used to deposit tellurium films on to glass and freshly cleaved mica substrates. Environmental conditions are optimized to obtain better crystallinity and deposition rate. Grain size as large as 12.0 µm on glass and 6.4 µm on mica substrate has been obtained. Structure of the films was analysed by X-ray diffraction and scanning electron microscopy.
Effects of Oxygen on CVD Diamond Synthesis
Authors: Kawato Takashi , Kondo Ken-ichi
Published: November 2005

In order to investigate the influence of oxygen on the chemical vapor deposition (CVD) of diamond, gas mixtures of H2–CH4and H2–CH4–O2were used to carry out thermal CVD. The effects of the oxygen additive were examined by gas chromatography for the exhaust gas and by a characterization of the deposits. With the addition of oxygen, the deposition of graphitic or amorphous carbon could be suppressed, so that the growth rate of diamond increased and the pressure range for the synthesis of diamond was extended. These effects resulted from the fact that the acetylene concentration in a deposition chamber is significantly reduced upon the addition of oxygen.
Interface Analysis of Al2O3/InP Structure Prepared by Molecular Beam Deposition
Authors: Ohyama Hideaki , Narusawa Tadashi , Nakashima Hisao , Takagi Shin-ichi , Sugano Takuo
Published: November 2005

We have applied disorder-sensitive high-energy ion scattering together with the C-V method to an interface study of Al2O3/InP, which was prepared with well-controlled molecular beam deposition. Low interface state densities (the minimum value near the midgap is ∼1×1011cm-2eV-1) have been obtained in the present work. Measurements of the interface disorder for these samples suggest that there is a correlation between the interface state density and the interface disorder. It is necessary to lower the interface disorder to obtain low interface state densities.
An Extra Diffusion of Zn into GaAs in Low Concentration Range : Application of the Model of Varying Charge Transfer
Authors: Kazmierski K. , Launay F. , Cremoux B.de.
Published: November 2005

A second diffusion of Zn has been observed in GaAs in the low-concentration range. The behaviour is similar to that of double diffusion in InP. The effect of zinc activity in the vapour phase has been studied using a semiclosed-box system. The observed profiles of Zn have been explained using a model of varying charge transfer by vacancy centers during interstitial-substitutional interchanges.
Nb-Oxide-Pb Tunnel Junctions Fabricated Using CF4 Cleaning Process. (III) Preparation of Planar dc SQUID
Authors: Katoh Yujiro , Asano Hidefumi , Tanabe Keiichi , Michikami Osamu
Published: November 2005

This paper discusses the preparation of thin-film planar dc superconducting quantum interference devices (SQUIDs). Nb-oxide-Pb tunnel junctions fabricated using CF4 cleaning process (CFCP) and Pd thin-film shunt resistor were employed. It was demonstrated that the two junctions in a SQUID have symmetrical and wellcontrolled junction parameters. Pd adhesion with oxidized Si could be improved by ultrathin Zr underlayers. The Pd films allowed good controt of the sheet resistance. The SQUIDs are very reliable in regard to room-temperature storage and thermal cycling.
A Feasibility Study on the Use of Amorphous Silicon as Optical Recording Medium
Authors: Lee Ming-Chiln , Tseng Chau-Jern , Huang Chien-Rong , Huang Tzer-Hsiang
Published: November 2005

We have shown that amorphous silicon (a-Si) prepared by the plasma enhanced chemical vapor deposition (PECVD) method underwent an 80 dB enhancement in transmission when subjected to heat treatment and laser annealing. As this characteristic has a high potential in the optical disk application, careful studies of contrast transmission with respect to annealing power density, sample film thickness, and probing wavelength are presentted. We further prove with Raman scattering that this enhancement is indeed due to the laser induced amorphous-to-crystalline phase transition.
Growth Conditions of Subgrain-Free LiNbO3 Single Crystals by the Czochralski Method
Authors: Shigematsu Koji , Anzai Yutaka , Morita Shigeru , Yamada Masamichi , Yokoyama Hikaru
Published: November 2005

Subgrain-free LiNbO3 single crystals were grown by the CZ method. It is generally accepted that thermal fluctuations are a serious drawback in growing a high-quality crystal. However, we found that subgrain-free LiNbO3 crystals could be grown only under regular thermal fluctuation of the melt. In order to analyze the effect of thermal fluctuation, we measured such properties of molten LiNbO3 as the viscosity, density, surface tension, and electrical conductivity. From these measurements, we speculate the existence of clusters made of niobium oxide molecules and lithium oxide molecules below 1280°C. The volume fraction of these clusters decreases as the temperature of molten LiNbO3 increases. A reduction of the density of these clusters prevents LiNbO3 crystals from producing subgrains. This reduction is regarded as one of the necessary conditions required for growing a subgrain-free LiNbO3 single crystal.
Characteristics of Hydrogenated Amorphous Silicon Films Prepared by Electron Cyclotron Resonance Microwave Plasma Chemical Vapor Deposition Method and Their Application to Photodiodes
Authors: Kobayashi Kazuhiro , Hayama Masahiro , Kawamoto Satoru , Miki Hidejiro
Published: November 2005

The electron cyclotron resonance microwave plasma chemical vapor deposition (ECRPCVD) method has been applied to prepare a-Si:H films. A high deposition rate of 136 nm/min was achieved. Even without substrate heating and with the high deposition rate, a-Si:H films prepared by ECRPCVD have sufficient characteristics, as follows: the dark conductivity is 3-4×10-10S/cm, ηµτ is 4.2×10-5cm2/V and the optical band-gap is 1.81 eV. Furthermore, the electric characteristics are somewhat improved with substrate heating.
Hydrogenated amorphous silicon films prepared by ECRPCVD without substrate heating and with a high deposition rate of 136 nm/min have been applied to ITO/a-Si:H/Cr Schottky-barrier photodiodes. These photodiodes have sufficient characteristics to be applied to image sensors for a facsimile reader and other systems.
High Energy Electron Transport in Hydrocarbons
Authors: Racz Istvan , Ohki Yoshimichi
Published: November 2005

High energy electrons play an important role in triggering the damage process in polymeric dielectrics, causing ageing or initiating avalanche breakdown. In order to investigate the transport properties of these high energy electrons, first paraffin is used as the model material for polyethylene, and the interfacial photoemission technique, the method to inject electrons into it. The results are compared with those measured using polyethylene sample. The mean free path of the photoelectrons deduced from the energy distribution curves was found to be in the order necessary for electron multiplication, thus indicating the possibility of the occurrence of avalanche breakdown. The possible energy loss process of the high energy electrons injected into hydrocarbons is also discussed.
Estimation of Small Signal Gain and Saturation Intensity in a Waveguide CO2 Laser by a Curve-Fitting Technique
Authors: Kurosawa Tomizo
Published: November 2005

Output power curves as a function of the frequency have been measured by heterodying between a gas flowing waveguide and a conventional sealed-off CO2 laser with a W–Ni point contact diode. The small signal gain, saturation intensity, collision-broadened linewidth and frequency tunability are simultaneously estimated by fitting a theoretical equation to output power curves according to a least-squares technique.
Laser-Induced Fluorescence and Doppler-Free Polarization Spectra in a Low Density Hydrogen Plasma
Authors: Arata Yoshiaki , Miyake Shoji , Matsuoka Hidesato
Published: November 2005

The Hα spectral line profile in a low-density hydrogen plasma of a microwave discharge has been measured by the laser-induced fluorescence auad the Doppler-free polarization spectroscopy methods with a pulsed high-power tunable laser. The saturation characteristics of the output signals in each method were examined in detail with observations of typical saturation broadening. The original homogeneous width of the line was estimated in the limit of no laser pumping, and various factors governing this width are discussed while demonstrating the importance of the clarification of molecular processes in the discharge. In the Doppler-free spectra a large distortion of the spectrum was also found under different operating conditions; it was attributed to the plasma opacify effect.
Laser Stimulated Desorption from Compound Semiconductors, Dimerization Enhanced Phase Transition
Authors: Namiki Akira , Cho Seiji , Ichige Kenji
Published: November 2005

Laser stimulated desorption (LSD) of neutral particles has been investigated in compound semiconductors MX of GaN, GaP, GaAs and CdS. No effects of crystallographic orientations on the characteristics of LSD, desorption yields, mean kinetic energies, and speed ratios have been recognized among (111) and (100) orientations in GaP and GaAs. This fact suggests that LSD does not follow the unimolecular dissociation of locally excited surface bonds, but occurs via a bulky event involving a phase transtion. The threshold laser powers for LSD were correlated to the crystal bond ionicities f
i, which are good measures for the structural stability of tetrahedral covalent solids. It was found that with increasing f
i of the solids, threshold laser powers tend to decrease. The dominant species ejected from MX were found to be in the forms of monomer M and X as well as dimer X2. The ratio of the yields of X2 to those of X increases as the single-bond energy of X2 increases. Considering these experimental results, we propose a model of a non-local electronic excitation mechanism for LSD; namely, LSD occurs via the dimerization enhanced phase transition in a high-density electron-hole plasma.
Photoacoustic and Luminescence Spectra of CdS Fine Particles
Authors: Arai Toshihiro , Yoshida Takehito , Ogawa Tsutomu
Published: November 2005

Some size effects of the relaxation mechanism of optically excited electrons in CdS fine particles were investigated by means of photoacoustic and luminescence spectroscopies. The intensity of green luminescence (∼2.47 eV) decreased and its peak position shifted to the lower-energy side upon decreasing the particle size. The impurity luminescence which appears in the longer-wavelength region, red emission (∼1.7 eV), did not vary as much upon decreasing the particle size to ∼40 nm in diameter. The absorption spectrum in the intrinsic energy region for a small-size particle, which was determined from the photoacoustic effect, formed a long tailing towards the lower-energy side. The non-radiative recombinalion rate, thermal relaxation rate, increases with decreasing particle size. These phenomena were interpreted to originate from the increment of the ratio of the surface to volume in small-size particles.
GaAlAs/GaAs Surface Emitting Laser with High Reflective TiO2/SiO2 Multilayer Bragg Reflector
Authors: Kinoshita Susumu , Sakaguchi Takahiro , Odagawa Tetsufumi , Iga Kenichi
Published: November 2005

First, it has been made clear that the important parameters of the SE laser are its active layer thickness d and the mirror reflectivity R. The required values of three parameters such as threshold gain g
th, threshold current density J
th, and differencial quantum efficiency ηd are obtained for d=2∼3 µm and R=95%. At this condition g
th is estimated as 300 cm-1 (N
th=3×1018 cm-3), J
th is 25∼30 kA/cm2, and ηd is 40%. Next, in order to obtain a reflectivity as high as 95%, a TiO2/SiO2 multilayer Bragg reflector was introduced. It was found that a good quality TiO2 film could be evaporated by leaking oxygen through a variable leak valve to hold 1×10-4 Torr. Then, a 7-pair TiO2/SiO2 multilayer Bragg reflector was fabricated; its peak reflectivity was 95% at 8800 Å. A room-temperature pulsed operation of a GaAlAs/GaAs SE layer was achieved and the minimum threshold current was reduced to as low as 150 mA when a round mesa was fabricated to 20 µm in diam.
A Crystal Spectrograph for a Soft X-Ray Measurement in Imploding Plasma Experiments
Authors: Shimoda Katsuji , Yamamoto Toshikazu , Takada Satoshi , Sone Hisao , Hirano Katsumi
Published: November 2005

To measure the wavelength of a soft X-ray locally fluctuating plasma, a compact, crystal spectrograph was constructed. The spectrograph was designed so as to record lines and a pinhole picture on a photographic film for a precise measurement of the wavelength. In order to obtain a high dispersion, a flat crystal with an RAP (double atomic spacing; 26.12 Å) was installed. Using the spectrograph, ArXVII and ArXVI lines generated by plasma focus were observed using both time-resolved and time-integrated techniques with sufficient dispersion and resolving power.
Effect of the Electron-Irradiation-Induced-Contamination of the Etching Process of a Photoresist
Authors: Miyoshi Motosuke , Norimatsu Kenji , Okumura Katsuya
Published: November 2005

Electron-irradiation-induced-contamination interferes with the progress of etching and results in an etch residue. Hydrocarbon molecules from an irradiated photoresist mainly contribute to the growth of a contamination layer. There is a threshold dosage below which no etch residue exists.
Electron Transport in Oxygenated Amorphous Hydrogenated Silicon Prepared by Reactive Sputtering
Authors: Jiranapakul Koarakot , Shirafuji Junji
Published: November 2005

The effect of oxygen-doping on the electron transport in sputtered hydrogenated amorphous silicon has been studied by means of a time-of-flight technique. Incorporation of a slight amount of oxygen enhances both the mobility and the mobility-lifetime product. An electron drift mobility as high as 8×10-2cm2/V·s at room temperature with a non-dispersive character is observed. The enhancement of the electron mobility and the non-dispersive electron transport in slightly oxygen-doped films are discussed on the basis of two-fold coordinated oxygen atoms and oxygen-related donors.
Sputter-Deposition of [111]-Axis Oriented Rhombohedral PZT Films and Their Dielectric, Ferroelectric and Pyroelectric Properties
Authors: Adachi Masatoshi , Matsuzaki Tokuo , Yamada Takehiro , Shiosaki Tadashi , Kawabata Akira
Published: November 2005

[111]-oriented PZT films have been successfully grown with good epitaxy onto epitaxial platinum film substrates by the rf-magnetron sputtering method using Pb enriched PZT(90/10) targets. The sputtering conditions for growing epitaxial films were investigated. Crystallographic identifications of the films were made by the X-ray and RHEED measurements. Dielectric, ferroelectric and pyroelectric properties of these films were measured. Pyroelectric coefficients at room temperature were determined as 45 and 3×10-9 C/cm2 K for epitaxial PZT films with poling and without poling treatments, respectively. Epitaxial PZT films sputtered on Pt/sapphire possess desirable properties for potential applications to pyroelectric devices.
Saturation of ac Surface Photovoltages due to Photocapacitances in a Strongly-Inverted Oxidized p-Type Silicon Wafer
Authors: Munakata Chusuke , Honma Noriaki
Published: November 2005

Surface photovoltages (SPVs) excited with a chopped 633 nm-wavelength photon beam (PB) were measured at various PB power densities from 0.78 to 8800 W/m2. The PB power was measured before the PB came into the wafer holder; no correction due to the wafer holder absorption or wafer reflection was added to the PB power. SPVs begin to saturate at 2.3 W/m2 and almost become saturated at 780 W/m2. This is considered to be caused by the inversion capacitance, or, simply, photocapacitance. This capacitance is proportional to the power density, at least up to 780 W/m2.
Reversed Domain Generation in Co–Cr Films
Authors: Uesaka Yasutaro , Ohta Norio , Suzuki Hiroyuki , Tsumita Norikazu , Ajiro Yoshitami
Published: November 2005

X-band ferromagnetic resonance (FMR) spectra and Kerr loops were investigated in Co–Cr films with perpendicular anisotropy produced by sputtering. A hysteresis phenomenon was observed in the X-band FMR spectrum between increasing and decreasing magnetic fields. The origin of the hysteresis is attributed to the generation of reversed domains which occur prior to the beginning of domain wall motions in a very thin (0.02 µm) film when the magnetic field is reduced. The magnetic field width of the reversed domain generation in Co–Cr films increases with increasing film thickness. The coercivity of a Co–Cr film is not determined solely by the generation field of reversed domains.
Molecular Beam Studies of Thermal Decomposition of Glycine on Solid Surfaces
Authors: Okude Shin'ichiro , Matsushima Fusakazu , Kuze Hiroaki , Shimizu Tadao
Published: November 2005

A molecular beam technique for studying the decomposition of vapor-phase glycine on solid surfaces has been developed. The decomposition probability of glycine on the surfaces of polycrystalline molybdenum oxide and glass was measured as a function of the surface temperature. Decomposition products were quantitatively analyzed with a mass spectrometer in the temperature range of 420–800 K. The probability of decomposition of glycine per one collision with molybdenum oxide was found to be almost unity at a high surface temperature (∼800 K), while that with glass was less than 0.15 in the observed temperature range. The values of activation energy E and the pre-exponential factor S
Z
2/Z
1 for the decomposition are determined. A new model based on the transition state theory to evaluate the values of the pre-exponential factor is proposed.
Observation of the Variable-Range Hopping Conduction in Amorphous In–Se Films
Authors: Watanabe Ichiro , Sekiya Toshiyuki
Published: November 2005

The temperature dependence of the Seebeck coefficient and the electrical conductivity were measured for amorphous In–Se films with compositions around In40Se60. The variable-range hopping conduction is dominant nearly up to or slightly above room temperature. Above that temperature activation conduction begins by electrons being supplied from donor-like localized states at about 0.4 eV below the conduction band.
Zinc-Diffusion in GaAs Using a Sintered Ternary Source
Authors: Werner J. , Melchior H.
Published: November 2005

A ternary Zn3As2–ZnAs2–GaAs source for the diffusion of Zn in GaAs has been developed by a low temperature sintering technique that does not require special safety precautions. Wafers diffused using this source remained free of damage. Doping concentrations and diffusion depths agree with the results of the best high temperature Ga/As/Zn diffusion sources.
Silicon Selective Epitaxial Growth over Thick SiO2 Islands
Authors: Kasai Naoki , Kimura Masakazu , Endo Nobuhiro , Ishitani Akihiko , Kitajima Hiroshi
Published: November 2005

Silicon selective epitaxial overgrowth from a seed area to thick SiO2 islands top surface using chemical vapor deposition method was studied. A single crystal silicon layer on SiO2 islands without stacking faults was obtained on {100} and {110} oriented wafers. Lateral to vertical growth ratio is influenced by the substrate orientation and the striped pattern sidewall orientation. Facet planes appearing at a lateral growth front are caused by the growth rate anisotropy.
Determination of the LO–TO Splittings in the Raman Spectra of Ferroelectric Triglycine Sulfate (TGS)
Authors: Tashiro Kohji , Yagi Noriko , Kobayashi Masamichi , Kawaguchi Takeo
Published: November 2005

The LO–TO splitting of Raman bands has been measured for the first time for a ferroelectric triglycine sulfate (TGS) single crystal at liquid-nitrogen temperature as well as at room temperature (LO and TO represent the longitudinal and transverse optical modes, respectively). The splitting width ranges from 0 to 30cm-1. The angular dependence of the frequency shift has been measured for both the A and B modes, from which the direction and amplitude of the transition dipole moments of the polar optical phonons were evaluated based on the lattice dynamical equations. A Rayleigh wing, which originates from the thermal fluctuation of dipoles, has been observed in the vicinity of the Curie transition point (about 49°C) and was compared with such previously reported results as X-ray critical scattering.
A New Plasma Diagnostic Capacitance Method
Authors: Dengra A. , Colomer V. , Hernandez M. A.
Published: November 2005

In this paper, a new plasma diagnostic method based on a theoretical model which permits the calculation for the associated admittance with a cylindrical or spherical ion sheath probe is reported. In this way a theoretical curves set of the ion sheath capacitance versus frequency, for several electron densities and temperatures is obtained. The identification with the appropriate theoretical curve of any experimental value of ion sheath capacitance permits to obtain the electron plasma density and temperature. The results obtained with this method are in agreement with the experimental values obtained by using the I–V characteristic method. This new method has advantage over other diagnostic techniques based on Langmuir probes, since the probe current and therefore the plasma perturbation is very small.
Ar+–Si Sputtering in Low Temperature and High Vacuum Pressure Ranges
Authors: Hosaka Sumio
Published: November 2005

The influence of temperature and pressure on the sputtering yield was examined in a low-temperature range of -100 to 300°C and a high-pressure range of 5×10-5 to 5×10-4 Torr. This work was carried out with an ion-etching system using a Kaufman-type ion source. The results suggest that the temperature and pressure influence the sputtering or applicaltions using sputtering at 1 keV Ar+–Si ion bombardment.
Fluorescence from Varnishes for Oil Paintings under N2 Laser Excitation
Authors: Miyoshi Tadaki
Published: November 2005

The fluorescence spectra of varnish films have been measured as a function of the storage time. The varnishes used were made from natural resins (copal, mastic and dammar), synthetic resin and beeswax. Peak wavelengths of the fluorescence shifted to longer wavelengths with long-time storage. The effect of light on the fluorescence spectrum was found to be small.
Comparative Study on the Electronic Properties of p-Xylene Polymers Prepared by Plasma-Polymerization and Vapor Phase Pyrolysis
Authors: Takai Yoshiaki , Mizutani Teruyoshi , Ieda Masayuki
Published: November 2005

High-field conduction and photoconduction were investigated on thin polymer films prepared from p-xylene by two different polymerization processes: plasma-polymerization and vapor phase polymerization of p-xylylene bi-radicals. These processes gave amorphous and semicrystalline polymer films, respectively. The physical and chemical differences between these polymers are discussed in terms of their electronic properties. The results show that plasma-polymerization under a low discharge power at a high frequency (13.56 MHz) resulted in polymer films. Their electronic properties, determined by the short-range molecular order, were similar to those of semicrystalline poly-p-xylylene, while the properties determined by the long-range order, such as charge transport, were not.
Gas-Sensitive Electrical Conduction and its Mechanism in a Ag/Insulator System with Locally Discontinuous Structure
Authors: Yasuda Tetsuji , Komiyama Hiroshi , Tanaka Kazunobu
Published: November 2005

The gas-sensitive electrical conduction of a locally discontinuous Ag-thin-film/insulator element is described and its mechanism is discussed on the basis of experimental results. A thin-film element was found to show essentially the same gas-sensing phenomenon as had been previously reported in a conglomerate element, which is a dispersion of Ag ultrafine particles within a porous matrix. A filament model is proposed to explain the gas-sensing phenomenon in terms of the ionic movement of Ag as well as the structural stability of the Ag filaments.
Japanese Indoor Calibration Method for the Reference Solar Cell and Comparison with the Outdoor Calibration
Authors: Shimokawa Ryuichi , Nagamine Fumiaki , Miyake Yukiharu , Fujisawa Kazuya , Hamakawa Yoshihiro
Published: November 2005

Details of the established Japanese indoor calibration method for solar cells were introduced and various kinds of reference cells were calibrated using the indoor and outdoor methods for comparisons. It was found that both calibrated values were very consistent and nearly equal for crystalline Si cells, while the total irradiance detected with an absolute spectro-radiometer in the indoor calibration was about 2% higher than that detected with a pyranometer EKO MS-801 confirming to the current World Radiometric Reference. Also, the calibration errors due to a deviation from the cosine response for a low incident angle were found to be about 2% for an inert gas-sealed crystalline Si cell and about 1% for unpackaged and module-packaged crystalline Si cells.
Experimental Characterization of Electrical Conduction in Undoped Polycrystalline Silicon Thin Films
Authors: Kim Dae M. , Qian Feng , Ahmed S. S. , Park H. K. , Sachitano J. L.
Published: November 2005

Electrical conduction in undoped LPCVD polycrystalline silicon was examinated at both low and high fields. The physical mechanisms pertinent to the current-voltage (I–V) characteristics were experimentally interrogated. Specially, the localized self heating near grain boundaries that is responsible for nonlinear I–V behavior was further corroborated by the temperature dependence of the resistivity and the high-feld I–V behavior. These data were quantified, based on local Joule heating and a concomitant rise in the sample temperature.
A Versatile Spectrometer by the Use of a Pressure-Scanned Fabry-Perot Interferometer and a Piezoelectrically-Scanned Fabry-Perot Interferometer in Tandem Arrangement
Authors: Hikita Tomoyuki , Suzuki Hiroko , Ikeda Takuro
Published: November 2005

A versatile spectrometer system which uses a pressure-scanned Fabry-Perot and a piezoelectrically-scanned Fabry-Perot in tandem arrangement is described. This system can be used either in synchronous scanning mode where two Fabry-Perots are scanned simultaneously or in band-pass filter mode where the pressure scanned Fabry-Perot is fixed at a frequency and only the piezoelectrically-scanned Fabry Perot is scanned. The former mode is used for the spectroscopy which needs high-resolution in relatively wide frequency region. The latter is suitable for very high-resolution spectroscopy such as precise measurements of Brillouin lines etc.
ESR Dating Utilizing Change in Valency or Ligand of Transition-Metals
Authors: Miki Toshikatsu , Kai Ayako , Ikeya Motoji
Published: November 2005

A physicochemical dating method which utilizes changes in valency or ligand of transition metals by various physical and chemical processes is proposed. We have successfully applied this method to the dating of a biological material of coagulated blood by detecting the change of the ligand of heme-iron with ESR. This method may be useful for dating not only bilogical materials but also minerals and fossils in earth sciences.
Crystal Structure of the High Tc Superconductor YbBa2Cu3O7-δ
Authors: Asano Hajime , Ishigaki Tōru , Takita Kôki
Published: November 2005

The crystal structure of the high T
c superconductor YbBa2Cu3O7-δ is determined by Rietveld analysis of X-ray powder diffraction data. The crystal system is orthorhombic (space group Pmmm) with lattice parameters a=3.8710(2) Å, b=3.8018(2) Å and c=11.6576(5) Å. The structure is isomorphic with YBa2Cu3O7-δ. The layered perovskite structure with the tripled c-axis exhibits ordering of Yb and Ba, an oxygen-deficient Yb layer at z=1/2 and preferential oxygen occupation on the basal Cu plane. The compound shows superconductivity at 90 K (midpoint) with the transition width of 3.0 K.
Thermal and X-Ray Analyses of High Temperature Superconductor YBa2Cu3O6.74
Authors: Kikuchi Masae , Syono Yasuhiko , Tokiwa Ayako , Oh-ishi Katsuyoshi , Arai Hide , Hiraga Kenji , Kobayashi Norio , Sasaoka Takaaki , Muto Yoshio
Published: November 2005

In situ observation of oxygen absorption and desorption during heating and cooling cycle with TG and DTA was done to determine the optimum preparation conditions of high T
c Y-Ba-Cu-O compounds. We suggest the best recipe in air is to fire the raw mixture of 1/2Y2O3, 2BaCO3 and 3CuO at 930°C for more than 10 h, followed by slow cooling in the furnace to take as much oxygen as possible within the specimen. With this method single phase material of an orthorhombic superconducting oxide YBa2Cu3O6.74 with T
c=91.3 K was synthesized, with orthorhombic unit cell dimensions of a=3.8180(6) Å, b=3.8888(7) Å, and c=11.668(2) Å.
Annealing-Temperature Dependence of High Tc Superconductivity of Y1-xBaxCuO3
Authors: Tonouchi Masayoshi , Kobayashi Takeshi , Kita Sadamu , Ohshima Ryuichiro , Fujita Francisco Eiichi
Published: November 2005

Y1-x
Ba
x
CuO3 ceramic superconductors were prepared under precise annealing-temperature control, and systematically measured in their crystalline and electrical characteristics. The critical temperature showed clear dependence on the annealing-temperature, the dependence itself being different from composition to composition. However, optimizing the annealing-temperature, the ceramics with an orthorhombic structure exhibited almost the same zero-resistance temperature (87-89 K) regardless of the Ba content (x=0.5-0.7).
XPS Investigations of Ni-Fe Alloy and Fe Films
Authors: Nagai Yasuhiro , Senda Masakatsu , Toshima Tomoyuki
Published: November 2005

This paper reports the results of experimental investigations into the chemical shifts of Fe 2p, Ni 2p and N 1s in Ni-Fe alloy and Fe films. Through XPS analysis on Ni-Fe film composition, it is known that the binding energy of Fe0 2p increases and the satellite around 859 eV shifts toward lower binding energy with an increasing Ni fraction, instead of a Ni core level shift. Additionally, Fe species are confirmed to be more preferentially oxidized than those of Ni in the Ni-Fe alloy surface. Furthermore, an observed core level shift of N 1s infers that N in iron films formed in nitrogen atmosphere chemically reacts with Fe species even though these films were not made up of iron nitrides.
Nanometer Patterning by Focused Low Energy Electron Beam Lithography
Authors: Sugita Akio , Kakuchi Masami , Tamamura Toshiaki
Published: November 2005

Focused low energy electron beam was applied for nanometerscale pattern delineation. A resist exposure with an electron energy less than 10 kV causes two problems, that is, a limited penetration depth and the scum formation due to charging-up effect. These problems were solved by using an electrically conducting 2-layer resist system composed of thin top imaging layer of silicone containing resist and conducting CVD carbon film as a bottom resist. Nanometer patterning as fine as 40 nm can be delineated by very low energy electron exposure with no electron energy dissipation in a substrate layer.
Monolayer and Bilayer High Steps on Si(001)2×1 Vicinal Surface
Authors: Nakayama Tomonobu , Tanishiro Yasumasa , Takayanagi Kunio
Published: November 2005

Atomic steps on Si(001)2×1 surfaces are observed by reflection electron microscopy. On the Si(001)2×1 vicinal surface having the inclination of 0.01°-0.1° towards the [100], the 2×1 and 1×2 domains are formed alternately, being separated by a monolayer-high step. The width of the terrace varies systematically from domain to domain. This is explained by the fact that the dimers tend to aligh parallel to the step, running along the [110] or [1̄10] direction; the domain in which the dimers are aligned parallel to the step expands and the other domain shrinks.
Crystal Structure of the Orthorhombic Form of Ba2YCu3O7-x at 42 K
Authors: Izumi Fujio , Asano Hajime , Ishigaki Tōru , Takayama-Muromachi Eiji , Uchida Yoshishige , Watanabe Noboru
Published: November 2005

The crystal structure of the low-temperature form of Ba2YCu3O7-x
at 42 K was refined by the Rietveld analysis of TOF neutron powder diffraction data. This material is orthorhombic with space group Pmmm and lattice constants a=3.8800 Å, b=3.8122 Å, and c=11.6264 Å. It has an oxygen-deficient triperovskite structure in which oxygen atomson a z=1/2 plane are lacking completely, two oxygen sites on a z=0 plane are partially occupied, and Ba2+ and Y3+ ions are ordered in a [Ba-Y-Ba]∞ sequence along the c axis. The occupation factors of oxygen at (1/2, 0, 0) and (0, 1/2, 0) are 0.84 and 0.05, respectively.
Phase Transformation in the Superconductor Ba-Y-Cu-O and La-Sr-Cu-O Compounds
Authors: Sugiyama Masaaki , Suyama Ryuji , Inuzuka Takayuki , Kubo Hiroshi
Published: November 2005

The change of microstructure with phase transformation in the superconductor Ba-Y-Cu-O and La-Sr-Cu-O compounds are studied by in situ observation using a transmission electron microscope equipped with heating and cooling goniometer stages. It is confirmed in the Ba-Y-Cu-O system that tetragonal phase is transformed to the orthorhombic phase with (110) internal twins. In the La-Sr-Cu-O system, twins are also observed to appear on cooling, accompanied by the phase transformation, while they disappear reversibly on heating.
Crystal Structure of the Tetragonal Form of Ba2YCu3O7-x
Authors: Izumi Fujio , Asano Hajime , Ishigaki Tōru , Takayama-Muromachi Eiji , Uchida Yoshishige , Watanabe Noboru
Published: November 2005

The crystal structure of the high-temperature form of Ba2YCu3O7-x
was refined by the Rietveld analysis of TOF neutron powder diffraction data taken at 49 K. This compound is tetragonal with lattice constants a = 3.8533 Å and c = 11.7631 Å. It has an oxygen-deficient triperovskite structure, in which oxygen atoms on a z = 1/2 plane are missing, an oxygen site at (0, 1/2, 0) is about 9% occupied, and Ba2+ and Y3+ ions are completely ordered in a [Ba-Y-Ba]∞, sequence along the c axis.
Determination of Oxygen Nonstoichiometry in a High-Tc Superconductor Ba2YCu3O7-δ
Authors: Kishio Kohji , Shimoyama Jun-ichi , Hasegawa Tetsuya , Kitazawa Koichi , Fueki Kazuo
Published: November 2005

In order to elucidate the correlations between composition, structure and electrical properties of a high-T
c superconductor Ba-Y-Cu-O system, thermogravimetric measurement and chemical analysis of oxygen nonstoichiometry were made at a temperature range of 350 to 1000°C and under the oxygen partial pressure of 10-4 to 1 atm.
Within a stability range of the composition Ba2YCu3O7-δ, the oxygen deficiency, δ, was found to vary approximately from zero to 0.9, with associated mean valence of copper ions varying from 2.33 to 1.73. At a possible phase boundary region of tetragonal to orthorhombic crystal structures, no sign of discontinuity in δ was observed, suggesting its phase transition was of higher than a first order.
Electron Diffraction Study of Ba2YCu3O7-y(y=0.1-0.2)
Authors: Tanaka Michiyoshi , Terauchi Masami , Tsuda Kenji , Ono Akira
Published: November 2005

The space groups of the room temperature- and high temperature-phases of a high T
c superconductor Ba2YCu3O7-y
(y=0.1-0.2) have been determined to be Pmmm and P4/mmm by convergent-beam electron diffraction. Ribbon shaped diffuse scattering appeared at h=n, k=m/2 along the c
* direction when the specimen was cooled, but did not transform into superlattice reflections even at the temperature of liq. He. This deffuse scattering can be originated from zone-boundary soft phonons of the longitudinal (or pseudo one-dimensional breathing) mode due to the one-dimensional O-Cu-O chains.
Largely Anisotropic Superconducting Critical Current in Epitaxially Grown Ba2YCu3O7-y Thin Film
Authors: Enomoto Youichi , Murakami Toshiaki , Suzuki Minoru , Moriwaki Kazuyuki
Published: November 2005

Ba2YCu3O7-y
(BYCO) thin films have been epitaxially grown on SrTiO3 substrates by magnetron sputtering. The films exhibit zero resistance at 84 K, with a transition width of 6 K. The resistivity along the basal plane is one order of magnitude smaller than that along the c-axis, and the transport property is more metallic in the former direction. Furthermore, the critical current density is two order of magnitudes larger in the former direction than in the latter direction. These results strongly suggest a quasi-two-dimensional electronic structure in BYCO. The maximum critical current at the liquid nitrogen temperature has reached 1.8×106 A/cm2.
Influence of Annealing Condition on the Superconducting Behavior of High-T
c Oxide (Ba2Y)Cu3O7-x
Authors: Takagi Yoshiki , Liang Ruixing , Inaguma Yoshiyuki , Nakamura Tetsurō
Published: November 2005

The influence of annealing condition is presented for high T
c superconducting oxide (Ba2Y)Cu3O7-x
via investigation of the structure and electrical resistivity. It is found that T
c depends strongly on the annealing temperature and annealing time. T
c is higher for the sample with the greater orthorhombic distortion, that is, the greater difference between the lattice constant a and b.
Dependence of Absorption in Electrochromic V2O5 Thin Films on Crystallinity
Authors: Kobayashi Satoshi , Takemura Toshisato , Kaneko Futao
Published: November 2005

The absorption spectra in the colored state of electrochromic V2O5 thin films are classified into two types. One has the characteristic that the absorption in the visible region enhances with the injection of Na+, the other has an absorption band in the near-infrared region. The former type of film is amorphous and the latter is crystalline. The films prepared at substrate temperatures below 160°C are amorphous and those prepared above 180°C are crystalline. Amorphous films can turn into crystalline ones by the annealing.
FIB Exposure Characteristics of LB Film
Authors: Shiokawa Takao , Kim Pil Hyon , Toyoda Koichi , Namba Susumu , Suzuki Masayoshi , Matsui Shinji , Mori Katsumi
Published: November 2005

Exposure characteristics of 200 nm thick ω-tricosenoic acid Langmuir-Blodgett (LB) film have been investigated by 100 kV Be++ and Si++ focused ion beam. Etch depth and remaining film thickness dependence of LB film on ion dose have been determined. It has been found that the LB film can be used as a negative resist in 100 kv Be++ and Si++ beam exposure because it has the negligible etch depth. A fine pattern of the LB film with a line width of 100 nm and a height of 140 nm has been fabricated by Be++ focused ion beam.
Improvement in Differential Quantum Efficiency of 1.55 µm Distributed Feedback Lasers Grown by MOVPE
Authors: Itaya Yoshio , Fukuda Mitsuo , Noguchi Yoshio , Nakano Yoshinori
Published: November 2005

The effect of active layer thickness on differential quantum efficiency of 1.55 µm distributed feedback (DFB) buried heterostructure (BH) lasers is investigated. Advantages of MOVPE are confirmed in terms of active layer thickness control, which revealed significant improvement in differential quantum efficiency for thicknesses down to 0.06 µm in 1.55 µm range DFB lasers.
Direct Observation of the Incommensurate Superlattice of Rb2ZnBr4 by Transmission Electron Microscopy
Authors: Izumi Kunihide
Published: November 2005

The incommensurate superlattice of Rb2ZnBr4 was observed directly by a transmission electron microscope at room temperature. The lattice image of (001) planes (d=0.971 nm) was modulated by a superlattice image.
The mean distance of the superlattice was 3.38 nm and the wavelength q
0 was 0.286 C
*.
Two Secondary Fusion Reactions in Deuterium Fuel as a Diagnostic for Fuel-Pusher Mixing Rate in Inertial Confinement Fusion
Authors: Nishihara Katsunobu , Tsuji Ryusuke , Azechi Hiroshi
Published: November 2005

A new direct method to measure fuel-pusher mixing rate in deutrium fuel is presented. The method involves two secondary nuclear fusion reactions, D(t, n)4He and D(3He, p)4He, where triton and 3He nucleus are the products of primary fusion reactions. The required conditions for which the method may be applied are also briefly discussed.
Evidence of Antiferromagnetic Ordering in La2CuO4: Reinterpretation of 139La Nuclear Quadrupole Resonance (NQR) Data
Authors: Furó I. , Jánossy A.
Published: November 2005

A reinterpretation of the results of recent 139La nuclear quadrupole resonance (NQR) measurements on La2CuO4 by Kitaoka et al. (Jpn. J. Appl. Phys. 26 (1987) L397) reveals an antiferromagnetic order in this material at low temperature. The magnitude and the direction of the local field at the La sites are calculated. Supposing localized moments on copper atoms as the source of the magnetic field, it is shown that the ordering of magnetic moments on copper sites is not the simplest “chessboard” antiferromagnetic type.
Dynamic Switching Characteristics of Photoluminescence by an Electric Field in AlGaAs Quantum Well Structures
Authors: Ogura Ichiro , Yamanishi Masamichi , Kan Yasuo , Suemune Ikuo
Published: November 2005

Transient photoluminescence measurements for pulsed electric field at room temperature on AlGaAs quantum well structures have been carried out to clarify the characteristics of luminescence switching by an electric field. With our method, the radiative lifetime and nonradiative lifetime can be separately evaluated. Luminescence switching by electric field shows a high speed capability that is free from lifetime limitation. Based on the relationships between radiative and nonradiative processes, the intensity modulation of luminescence under the condition of a constant carrier density is demonstrated.
Anisotropic Upper Critical Fields of Orthorhombic Single Phase YBa2Cu3O7-δ Studied Using Preferentially Oriented Pellets
Authors: Takita Kôki , Akinaga Hiroyuki , Katoh Hideo , Uchino Takashi , Ishigaki Tōru , Asano Hajime
Published: November 2005

Anisotropic behavior of the upper critical fields H
c2 studied in as-sintered disk of YBa2Cu3O7-δ and the characterization of the samples by X-ray diffraction analysis are described. Highly oriented samples with c-axis perpendicular to the disk plane show anisotropic behavior of H
c2 for midpoints and isotropic behavior for the offset field H
c2
off defined at 1 % points: the slope (-dH
c2/dT) for midpoints is 3.8 T/K and 2.6 T/K for the magnetic field parallel and perpendicular to the disk plane, respectively, and the offset field is about 5-6 T at 80 K. An analysis based on a simplified model suggests the anisotropy factor ε of about 0.2 for YBa2Cu3O7-δ. The X-ray powder diffraction combined with Rietveld analysis together with the resistivity measurement show the samples to be single phase with orthorhombic structure and 90 Krange T
c.
RHEED Observation on (001)ZnSe Surface: MBE Surface Phase Diagram and Kinetic Behavior of Zn And Se Adatoms
Authors: Menda Kazunori , Takayasu Ichiro , Minato Tetsuo , Kawashima Mitsuo
Published: November 2005

Reflection high-energy electron diffraction (RHEED) studies have been performed on epitaxial (001)ZnSe surfaces. The phase diagram on the surface grown by molecular beam epitaxy (MBE) was obtained by observing changes of RHEED patterns as a function of beam flux ratio and substrate temperature. The desorption time of Se atoms and the adsorption time of Zn atoms were also obtained by measuring the time taken for the surface structure to change from a Se-stabilized surface to a Zn-stabilized one. The activation energy for the desorption of Se atom from a Se-stabilized surface was 1.02 eV.
Comments on the Delta Lattice Parameter Model
Authors: Ito Tomonori
Published: November 2005

The validity of Stringfellow's DLP model is examined from a microscopic viewpoint using a pseudopotential perturbation approach. The mixing enthalpies and lattice parameters of semiconductor ordered-alloys are calculated to investigate the relationship between them in the DLP model. The calculated results show that the bimodal distribution of the bond lengths does not actually affect the relationship in the DLP model.