bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Implantation of Carbon and Neon Ions in Pyrolytic Graphite
Authors: Yugo Shigemi , Kimura Tadamasa
Published: November 2005

The electrical properties of pyrolytic graphite implanted with carbon and neon ions of 40 keV to fluences ranging from 3×1012 to 3×1016 ions/cm2 were investigated by means of the resistivity, magnetoresistance, Hall effect and thermoelectric power.
An increase in resistivity and a decrease in magnetoresistance were observed with increasing ion fluence up to about 3×1015 ions/cm2, above which they saturated. The Hall effect and the thermoelectric power were found to be more sensitive to the ion fluence than the resistivity and magnetoresistance.
The behaviour with regard to the fluence became more complicated above a fluence of 1015 ions/cm2 than that of neutron-irradiated graphite. The results suggest the formation of many complex defects by ion implantation at high fluences.
Conoscopic Study of Liquid Crystal after Application and Removal of the External Electric Field
Authors: Miyoshi Katsuya , Yamada Shinichi , Miyahara Shinichiro , Yamashita Masafumi , Hashimoto Yoshiro , Yukinari Toshiro , Ishiguro Kozo
Published: November 2005

The temporal changes of conoscopic figures of electrically driven twisted nematic liquid crystal film are observed using a commonly available video camera. The unavoidable time lag effect of 16 ms of the lower side area of the image field of video camera compared with the upper side area which is caused by the finite scan time of the video camera is decreased to 2 ms by introduction of a “montage method”. By this method, the conoscopic figures are observed during a period of 0∼16 ms after turning on and turning off of the external electric field. The general behavior of L.C. molecules during this time interval confirm results reported in the previous paper (Jpn. J. Appl. Phys. 21 (1982) L616).
Crystal optical consideration of the observed conoscopic figure is presented.
Defect States and Electronic Properties of Post-Hydrogenated CVD Amorphous Silicon
Authors: Nakashita Toshio , Osaka Yukio , Hirose Masataka , Imura Takeshi , Hiraki Akio
Published: November 2005

Chemically vapor-deposited a-Si films containing no detectable bonded hydrogen were annealed in a hydrogen plasma. Bonded hydrogen to a density much more than the density of ESR centers in as-grown a-Si was found to be present in the hydrogenated films, with a depth profile described by a complementary error function. The effective spin-elimination-depth is estimated to be 0.5 µm, in which the spin density is reduced to 7×1016 cm-3. Photoconductivity and photoluminescence are closely correlated with the in-depth profile of hydrogens.
Effect of Irradiation on Amorphous Alloy Fe40Ni40P14B6
Authors: Hayashi Nobuyuki , Sakamoto Isao , Takahashi Tetsuo
Published: November 2005

The effect of 40 keV helium ion irradiation on the amorphous alloy Fe40Ni40P14B6 has been studied. Conversion electron Mössbauer spectra taken from the near surface region of the irradiated alloy show the presence of crystalline phases after a total does of 1.6×1018 ions/cm2. The crystallization process is found to be different from that in the thermally-treated amorphous alloy without irradiation. It is also observed that the crystalline phases appear together with surface damage such as blistering and exfoliation.
Superconducting BaPb1-xBixO3 Thin Films by RF Magnetron Sputtering
Authors: Suzuki Minoru , Murakami Toshiaki
Published: November 2005

RF planar magnetron sputtering has been adopted for obtaining superconducting BaPb1-x
Bi
x
O3 (BPB) thin films. Using a target with excess Pb and Bi, smoothly surfaced BPB films with T
c above 9 K were obtained at a deposition rate as high as 400 Å/min. It was found that the film properties do not strongly depend on sputtering pressure and voltage as compared with that of the conventional sputtering method. Furthermore, the reproducibility has been greatly improved.
Angular Dependence of Sputtering Yield of Au on Bombardment by 15 to 60 keV Ar+
Authors: Kojima Shu-ichi , Kimura Kenji , Mannami Michi-hiko
Published: November 2005

The angular dependence of the sputtering yield of Au on bombardment by 15 to 60 keV Ar+ has been studied experimentally. The increase in the sputtering yield as the angle θ of the incident beam is tilted from the normal is proportional to (cos
θ)-1. A critical angle at which the sputtering yield deviates from (cos
θ)-1 dependence is derived, and its dependence on the ion energy is compared with the results calculated from a model of the reflection of ions at the vacuum/target interface.
Isothermal Photocurrent Transient Spectroscopy of Gap States in Amorphous Chalcogenide Semiconductors
Authors: Natio Hiroyoshi , Nakaishi Masafumi , Nakayama Hiroshi , Okuda Masahiro , Nakau Tanehiro , Suzuki Akio , Matsushita Tatsuhiko
Published: November 2005

Gap state spectroscopy for determining the density and distribution of gap states in amorphous chalcogenide semiconductors is described. The method is based on the analysis of the transient current after a light pulse. The applicability of the method for determining the gap states in a-Se:Te films has been experimentally demonstrated. The experiments reveal that the gap states are relatively discrete states at energies of 0.42 eV and 0.34 eV above the valence band edge for 12 at.% Te:Se films and 18 at.% Te:Se films respectively.
Stability of Screen Printed CdS/CdTe Solar Cells
Authors: Uda Hiroshi , Nakano Akihiko , Kuribayashi Kiyoshi , Komatsu Yasumasa , Matsumoto Hitoshi , Ikegami Seiji
Published: November 2005

Some stability studies have been conducted on screen printed CdS/CdTe solar cells. Encapsulated CdS/CdTe modules exhibited excellent stabilities in output performance over 206 days when subjected to outdoor tests under various loading conditions. Accelerated tests were performed on unencapsulated cells. No degradation was observed after 90 days in continuous illumination test, A decrease in conversion efficiency due to an increase in series resistance of the unencapsulated cell took place under high temperature and high humidity tests. It is concluded that the increase in series resistance is caused by a decrease in adhesion between CdTe and C layers, and by swelling of the carbon layer with water absorption. Improved cells showed no degradation in efficiency over periods of 110 days at 100°C and over periods of 28 days at 65°C in 95% relative humidity.
Pressure Dependence of Disaccommodation in a Manganese Zinc Ferrite Single Crystal
Authors: Kuroda Kiyotaka , Kohn Kay , Sekizawa Hisashi
Published: November 2005

The disaccommodation in a Mn0.56Zn0.35Fe2.09O4 single crystal is studied in the temperature range from 250 to 300 K and a pressure range from 1 bar to 3.7 kbar. The results are analyzed using a model of Richter type magnetic after-effect. The values of the activation energy and the activation volume are estimated to be 0.59 eV and 1.2 cm3/mol, respectively. The results are discussed qualitatively in terms of existing theories.
Surface Roughness Dependence of the Dichromatic Elongated Speckle Pattern
Authors: Iwai Toshiaki , Asakura Toshimitsu , Takai Nobukatsu
Published: November 2005

This paper investigates experimentally the surface roughness dependence of the spatial structure of the dichromatic speckle pattern by using the autocorrelation function of the time-varying speckle intensity fluctuation. It is found that the correlation areas of the speckle field (i.e. average speckle shapes) occupying three different structural regions vary depending on the surface roughness of the diffuse object. The experimental results are compared with the theoretical ones and are found to be in fairly good agreement.
Analytical Description of Tunable Diode Laser Derivative Spectrometry
Authors: Sano Hiroya , Koga Ryuji , Kosaka Megumi
Published: November 2005

The instrument functions are investigated, and a quantitative description is given of how a second-derivative spectrometer employing a tunable diode laser attains the power to suppress spectral noise. As a result, it is found that the power can be improved by modifying the source-frequency modulation profile. The essence of this approach is to make the profile at its extreme as sharp as possible, and a hyperbolic sine profile with suitable parameters is proposed as the optimal profile that can be attained in practice.
New Negative Conductance in GaAs n+-n-n+ Ballistic Diode –Time-Dependent Computer Simulation–
Authors: Aishima Asuo , Fukushima Yoshifumi
Published: November 2005

Time-dependent computer simulations were performed to investigate the high-frequency effects of a GaAs n+-n-n+ ballistic diode. A new negative conductance, found previously using a simplified diode model, was confirmed by the numerical simulation, though the results differed considerably from those obtained previously. It is demonstrated that a GaAs n+-n-n+ ballistic diode exhibits negative conductance over a wide frequency range over 1000 GHz. The diode can be expected to act as a new solid-state source in the far-infared frequency range.
A Study of the Electric Discharge across a Shock Wave –Radiation Intensity Ratio–
Authors: Miyashiro Seiji
Published: November 2005

A theoretical study of the electric discharge across a shock wave was conducted. As the radiation intensity is proportional to the rate of generation of excited molecules, the ratio of the radiation intensity in front of the shock wave to that behind it can be obtained as a function of the density, density ratio and electric field.
The calculation results agree qualitatively with the experimental ones for E/P<500 V/cm · Torr.
This type of discharge is used for shock wave visualization and carries with it the possibility of increasing the discharge current and volume.
Fluid Observation with an Optical Fiber Photorefractometer
Authors: Takeo Takashi , Hattori Hajime
Published: November 2005

An optical fiber photorefractometer is used for observing fluid mixtures. The concentration of alcohol or sugar into water is measured by noting the change in refractive index. The flow pattern of insoluble mixture is characterizable by a passage frequency, f, or an occupation ratio in time, α, of inclusions. These parameters are related to the mixture ratio. The flow velocity may be estimated from the cross-correlation between outputs of two photorefractometric sensors placed at distances along the path of flow.
Contrast Ratio of Planar-Type Phase Change Guest-Host Color LCD
Authors: Suzuki Kenkichi , Hasegawa Shinji , Toriyama Kazuhisa , Ishibashi Tadashi
Published: November 2005

Light propagation along the helical axis of a planar cholesteric with dichroic dyes is calculated using the 2×2 Jones matrix formulation. The formulation is proved to be more useful than others for evaluating the dye LCD, as it reduces the number of parameters. The perceived contrast ratios are derived, and the dependences on the various cholesteric parameters are estimated. The results show that a small value of Δ
n and a high-order parameter are essential for improving the dye LCD contrast ratios.
Behaviors of Z-Discharged Plasma Channel for Beam Transport in LIB-Fusion
Authors: Kawata Shigeo , Niu Keishiro , Murakami Hiroyuki
Published: November 2005

The behaviors of a plasma channel for transporting intense ion beams by the z-discharge are studied by computer simulation. The z-discharge current reaches 50 kA, which is large enough to confine the beam in the channel. Two kinds of radial motion are induced in the channel; one is an inward pinch motion by the self-magnetic field and the other is an outward expanding motion accompanied by a shock wave.
Electron and Ion Energy Distribution Functions in Slide-Away Regime of TRIAM-1 Tokamak
Authors: Nakamura Kazuo , Satoh Takemichi , Toi Kazuo , Hiraki Naoji , Nakamura Yukio , Itoh Satoshi
Published: November 2005

The plasma properties, and the electron and ion energy distribution functions in particular, are studied in the slide-away regime of the TRIAM-1 tokamak, with the streaming parameter averaged over the plasma cross-section <ξ> being varied up to 0.4. In the range <ξ>\gtrsim0.1, the soft X-ray spectrum has a tail component, and the electrical resistivity derived from the loop voltage/plasma current characteristics is lower than the Spitzer-Härm resistivity, which is estimated from the experimentally-obtained Z
eff-value, electron temperature and electron density. Anomalous ion heating, however, does not occur, and the ion temperature agrees well with Artsimovich's scaling law.
Reversible Read-Write-Erase Properties of Styrene Oligomer Optical Recording Media
Authors: Kuroiwa Akihiko , Namba Kenryo , Asami Shigeru , Aoi Toshiki , Takahashi Kazuo , Nakagawa Shiro
Published: November 2005

Optical recording media consisting of a thermoplastic oligomer resin blended with a photoabsorbing pigment permit heat-mode pit writing without corona discharge, as well as heat erasure and rewriting. The properties of recording layers consisting of styrene oligomers having number-average molecular weights (M
n) of 400 or 3000 blended with copper phthalocyanine or anthraquinone pigment, when subjected to recording and playback operations with a helium-neon (He–Ne) laser, are investigated. In addition, full-surface heat erasure, and scanning heat erasure are discussed. Pits with an outside diameter of 2.5 µm were recorded (writing time, 2 µsec) with a 10 mW He–Ne laser light. A readout signal contrast (ratio of reflected light intensity in the absence of pits to that in the presence of pits) of 3 was obtained.
Formation of MIS Structure in Organic Cell Al/Pb-Phthalocyanine/ITO
Authors: Kanayama Seiji , Hiroi Masayuki , Okuyama Naoki , Yasunaga Hitoshi
Published: November 2005

The effects of ambient oxygen and air on the current vs voltage characteristic of the sandwich-type cell Al/Pb-Phthalocyanine/ITO (indium tin oxide) were investigated. While the effect of pure oxygen was small, exposure to air caused drastic changes in the characteristic: the linear relation with extremely low resistance observed in vacuum changed into a nonlinear characteristic with enhanced resistivity suggesting a tunnelling conduction, followed by a rectifying and photovoltaic characteristic. The extremely low resistance is a result of the formation of Al spikes penetrating though the PbPc to the ITO during preparation. The rectification and photovoltaic properties are considered to be due to a Schottky barrier with an oxide layer sandwiched between the Al and the PbPc, that is, an MIS-like barrier.
Electron Microscopic Study of the δ-Phase in Titanium Oxide Evaporated Films
Authors: Yamada Yukio , Yoshida Kazuhiko
Published: November 2005

The phase transformation of evaporated films of TiO0.5 into transition structure I has been demonstrated by in situ heating using an electron microscope. Single crystals of the δ-phase precipitate in the film during the transformation. Andersson's hexagonal model of the crystal structure of the δ-phase is verified by analysing diffraction patterns taken from these single crystals. The lattice parameters measured are a
d=5.022 Å and c
d=2.869 Å. The structural relationships among the α-phase, the δ-phase and transition structure I are examined.
Characteristics of Si Films Grown on Ion Processed Sapphire Substrates by Plasma Dissociation of Silane
Authors: Itoh Tadatsugu , Takai Hiroshi
Published: November 2005

Properties of Si films grown on (1̄012) sapphire substrates by means of the plasma dissociation of silane depend on the substrate temperature, the applied r-f power and the ion species implanted on the surface region of sapphire substrate before the epitaxial growth. A Si film with good crystalline quality can be grown with the substrate temperature above 800°C and a r-f power of 100 watts. Silicon ion implantation into the surface region of sapphire substrate with a dose of 5×1013/cm2 at 10 keV contributes in forming the reduction of disorder in the interfacial layer of Si film. Aluminium diffusion from the sapphire substrate to Si film is suppressed by O+ implantation into the sapphire surface, and the electron mobility is shown to have a correlation with Al concentration in the Si film.
Effect of Atmosphere on Dielectric Properties of Plasma Polymerized Ethylene
Authors: Hozumi Naohiro , Takao Toshiyuki , Kasama Yasuhiro , Ohki Yoshimichi
Published: November 2005

The effect of atmosphere after polymerization on dielectric properties of plasma polymerized ethylene (PPE) is studied. ESCA and ESR measurements show that the PPE sample traps oxygen rapidly when it is exposed to air after polymerization. They also show that heat treatment in argon or in hydrogen can reduce the number of residual free radicals. The change in dielectric properties of tan
δ and conduction current with atmosphere after polymerization can be explained if dielectric properties are closely related with residual free radicals and carbonyl groups formed in the sample.
Influence of Antistatic Agent on Electrical Conduction of Polyethylene
Authors: Mizutani Teruyoshi , Mitani Katsuhiko , Ieda Masayuki
Published: November 2005

The doping of an antistatic agent (As-1) into high-density polyethylene (HD-PE) strongly enhanced the charging currents and the thermally stimulated currents (TSC). Doped HD-PE showed a charging current peak due to the transient SCLC (space-charge-limited-current) and also the anomalous TSC flowing in the same direction as the charging current. These suggest an important contribution to the electrical conduction of the carrier injection from the electrode.
The charging current and the TSC in a two-layer (doped/undoped) specimen revealed that the electron injection from the cathode was dominant in doped HD-PE. The enhancement of electron injection is explained in terms of localized levels originating from As-1.
Preparation and Cathodoluminescence of CaS: Eu and Ca1-xSrxS: Eu Phosphors
Authors: Kato Katsuhiro , Okamoto Fumio
Published: November 2005

Red emitting phosphors, CaS: Eu and Ca1-x
Sr
x
S: Eu, have been prepared by the sulfurizing flux method. The products consist of well-crystallized and non-aggregated particles with smooth surfaces. CaS: Eu had the highest luminescence efficiency at 0.04 mole% of europium. The energy efficiency was about 50%, and the visual efficiency about 20% when compared with the standard red phosphor, Y2O2S: Eu. The relation between cathodoluminescence properties and activator concentration is discussed.
Study on Impurity Diffusion in Glow-Discharged Amorphous Silicon
Authors: Matsumura Hideki , Maeda Masaaki , Furukawa Seijiro
Published: November 2005

The diffusion of impurities in glow-discharged hydrogenated amorphous silicon (a-Si: H) films with various hydrogen contents is studied experimentally taking boron and antimony as examples of impurities. Similar impurity diffusion in hydro-fluorinated amorphous silicon (a-Si: F: H) films is also studied for comparison. It is found that the diffusion constant of impurities in a-Si: H depends only weakly on the impurity itself and is equal to the diffusion constant of hydrogen, and that the impurity diffusion is suppressed in a-Si: F: H film.
Electron Diffusion in Amorphous Tungsten Oxide Films
Authors: Yamada Shoji , Nakamura Tsuneo , Hiruta Yoichi , Urabe Kazuo , Kitao Michihiko
Published: November 2005

To elucidate electron diffusion in amorphous tungsten oxide film, the extension of the colored region is investigated in both one and two dimensions. When the film is touched with a metal (In or Sn) in an acid electrolyte, coloration appears from the contact. The colored region grows with the lapse of time. The boundary between the colored and uncolored regions is clearly defined, and the displacement of the boundary increases linearly with time in one-dimensional diffusion. On the other hand, it increases with the square root of time in two-dimensional diffusion. These phenomena can be interpreted from the assumption that the electron mobility in the colored region is much higher than that in the uncolored region.
Si and SiO2 Etching under Low Self-Bias Voltage
Authors: Arikado Tsunetoshi , Horiike Yasuhiro
Published: November 2005

Si and SiO2 reactive ion etching and the associated radiation damage were investigated employing CF4 in the low self-bias voltage region (less than 100 V). The etching was carried out using the substrate tuning method.
In the low self-bias voltage region, both Si etching and SiO2 etching proceed accompanied by the polymerization of CF
x
(x=0–3) radicals generated from the dissociation of CF4. The polymer deposited on the surface is decomposed by the subsequent ion bombardment to form F and CF
x
radicals, which take part in the etching and the polymer formation reaction again.
The radiation damage induced in the Si by energetic fluorocarbons depends strongly on the magnitude of the self bias. However, the damage induced by tens of volts can easily be removed.
High-Resolution Electron Microscopic Studies of CS Structure in Reduced WO3 Thin Crystals
Authors: Miyano Toshio , Iwanishi Masazumi , Kaito Chihiro , Shiojiri Makoto
Published: November 2005

The crystallographic shear (CS) structure in reduced WO3 crystals grown in vacuum-deposited amorphous films by electron heating, is investigated with a 200 kV electron microscope and by computer simulation. A new type of ordered (100) CS structure with the shear vector [101]a/4 is found in the reduced W
n
O3n-1 crystals with the (001) surface. Images which may be associated with ordered (100) oxygen vacancy walls and imperfect (100) CS planes are observed. The most reduced crystal observed is W2O5(n=2).
Development of a Laboratory EXAFS Facility
Authors: Tohji Kazuyuki , Udagawa Yasuo
Published: November 2005

An EXAFS (extended X-ray absorption fine structure) spectrometer incorporating a rotating anode X-ray source and standard optics with flat crystal is decreibed. By using a solid state detector to prevent harmonics and fast detection electronics to achieve a high count rate, we found that the conventional spectrometer can supply EXAFS spectra accurate enough for practical analysis. The systematic errors involved in EXAFS measurement are discussed in relation to the improvements designed into the present system.
AsH3 to Ga(CH3)3 Mole Ratio Dependence of Dominant Deep Levels in MOCVD GaAs
Authors: Watanabe Miyoko Oku , Tanaka Atsushi , Udagawa Takashi , Nakanishi Takatosi , Zohta Yasuhito
Published: November 2005

Dependence of the 0.8 eV electron trap (so-called EL2) concentration on the As/Ga mole ratio during growth in MOCVD GaAs has been investigated by varying growth temperatures. It has been found that a demarcation exists in the growth temperatures, which divides two regions with different trap concentration-As/Ga mole ratio relationships. The trap concentration increases with the As/Ga mole ratio by the one-fourth power at growth temperatures of 630°C and 660°C, while it increases with the As/Ga mole ratio by the one-half power at 720°C and 740°C. Corresponding with this difference, there is a slight difference in activation energies between the materials grown at the lower temperatures and those grown at the higher temperatures. A possible explanation based on thermodynamic considerations is presented.
Dielectric Properties of Sulfopropyl Sephadex Gel Beads Dispersed in Aqueous Solutions
Authors: Ishikawa Akira , Hanai Tetsuya , Koizumi Naokazu
Published: November 2005

Dielectric measurements were carried out on beds consisting of beads of the ion-exchange resin sulfopropyl Sephadex of the strong-acid type over the frequency range 30 Hz to 130 MHz. Striking dielectric relaxations were observed with dielectric increments of 102–103 in dielectric units and relaxation frequencies of 10 MHz. The relative permittivities and electrical conductivities of ion-exchange resins with different ionic froms were evaluated by the method proposed in recent investigations on the basis of theories of interfacial polarization. The values of the relative permittivities thus determined were unchanged irrespective of the ionic form and were smaller than the value for water. The values of the electrical conductivities changed with the ionic species of the counter ions.
Low-Temperature Characteristics of Buried-Channel Charge-Coupled Devices
Authors: Kimata Masafumi , Denda Masahiko , Yutani Naoki , Tsubouchi Natsuro , Uematsu Shigeyuki
Published: November 2005

The characteristics of buried-channel CCDs in the temperature range between 40 K and 300 K were studied. It was found that the transfer loss had a peak at about 130 K and increased rapidly below 90 K. In these specific temperature regions, the transfer loss depended on the clock period, the data cycle time and the clock fall time. The characteristics were analyzed based on free-charge transfer mechanisms and the Shockley-Read-Hall theory. The peak at 130 K was caused by a trap at the energy level 0.22 eV below the conduction band, and the increase below 90 K by the carrier freeze-out. Furthermore, the reduction of impurity concentration in the buried channel turned out to be an effective method of improving the transfer efficiency below 90 K.
Inner Frozen Metal Blanket Concept for an ICF Reactor
Authors: Tsuji Ryusuke , Ido Shunji
Published: November 2005

A new blanket concept for an inertial confinement fusion (ICF) reactor is proposed for protecting the structural materials from the impact of X-rays and plasma and controlling the plasma expansion. The inner blanket consists of several cm of frozen metal with holes for entry of the laser beams and for blow-off of the plasmas. The inner blanket is injected from the top of the reactor chamber at a speed of about 50 m/s. It is located near the fuel pellet (∼10 cm from the pellet and ∼5 m from the structural materials). When a microexplosion occurs, the inner frozen metal blanket is melted by the neutron heating and falls into the liquid metal pool, expanding and being guided by the magnetic field. The performance and neutronics calculations of the inner blanket are presented here using a simple model.
GaAs/AlxGa1-xAs Multilayer Reflector for Surface Emitting Laser Diode
Authors: Ogura Mutsuo , Hata Toshio , Kawai Naoyuki J. , Yao Takafumi
Published: November 2005

GaAs/Al
x
Ga1-x
As multilayer reflectors (MLRs) were fabricated for the cavity mirrors of a surface emitting laser diode by using MBE technique. Absolute reflectivity of the fabricated MLR with 20 repetition pairs of GaAs–Al0.5Ga0.5As reaches 0.94. This means 18 times lower cavity loss than GaAs-air interface when used as cavity mirrors. Good agreement of the reflectivity between theory and experiments is demonstrated.
Improvement of Crystalline Quality of Si Films on CaF2/Si Structures by Ion Implantation and Solid Phase Recrystallization
Authors: Asano Tanemasa , Ishiwara Hiroshi , Orihara Kouzo , Furukawa Seijiro
Published: November 2005

Crystalline quality of Si films grown on CaF2/Si heteroepitaxial structures has been improved by solid phase recrystallization of ion implanted amorphous layers. Both the Si/CaF2/Si(100) and Si/CaF2/Si(111) structures were bombarded with P+ ions to amorphize the surface region of the top Si films, and subsequently annealed at temperatures of 550–750°C. It has been found from ion channeling measurements that the crystalline quality of the Si films on CaF2/Si(100) structures is significantly improved after recrystallization at 750°C, but the quality of the Si films on CaF2/Si(111) structures is not improved by this method.
Modulation Doped GaAs–Ga1-xAlxAs Heterostructures Grown by Atmospheric Pressure MOVPE
Authors: Maluenda J. , Frijlink P. M.
Published: November 2005

Single and multiple period modulation doped GaAs–Ga1-x
Al
x
As heterostructures have been grown by atmospheric pressure metalorganic vapour phase epitaxy (AP-MOVPE). Single period structures exhibit electron mobilities of 6700, 80000 and 90000 cm2·V-1·s-1 at 300 K, 77 K, and 4 K for a sheet carrier concentration of 7.4×1011 cm-2, 8.3×1011 cm-2 and 3.9×1011 cm-2 respectively. To our knowledge, these values represent the best mobilities reported in this structure grown by AP-MOVPE.
Preliminary results on field effect transistors show a three fold increase of transconductance as temperature decreases from ambient to 77 K. Furthermore, we report mobility enhancement in “inverted” structures in which the conducting accumulation layers are located at the interfaces formed by growth of GaAs on top of (Ga, Alcp)As.
Magnetic Field Effects on Preparing Thin Homogeneous Ferroelectric Smectic Cells for Electro-Optical Microsecond Switches
Authors: Kondo Katsumi , Sato Yuzuru , Miyasato Keita , Takezoe Hideo , Fukuda Atsuo , Kuze Eiichi , Flatischler Kurt , Skarp Kent
Published: November 2005

The effects of a magnetic field on the preparation of homogeneously aligned thin cells are examined with a 1∼12 µm wedge-shaped cell of 2-methylbutyl p-(p-n-decyloxybenzylideneamino) cinnamate (DOBAMBC). Analyzing the properties of this cell, we concluded that the wide temperature range where the Sm A and the isotropic phases coexist is desirable for preparing thin cells of good quality. We actually widened this range by using an aged, degraded sample of DOBAMBC, and succeeded in obtaining a reasonably good cell of 3.5 µm thickness by applying 24 KG.
Electrical and Photo-luminescence Properties of ZnSe Thin Films Grown by Molecular Beam Epitaxy: Substrate Temperature Effect
Authors: Yao Takafumi , Ogura Mutsuo , Matsuoka Seiichi , Morishita Toshihide
Published: November 2005

The substrate temperature effect on electrical and PL properties of undoped MBE ZnSe has been investigated. Resistivity (ρ) of the epilayers shows an abrupt change with the substrate temperature (T
s): ρ∼106 ohm-cm for T
s∼250°C or \gtrsim400°C, while ρ∼1 ohm-cm for 280°C\lesssimT
s\lesssim370°C. The substrate temperature dependence of PL spectra of the epilayers reveals that (1) the high resistivity is caused by the increase of the SA centers above 400°C and below 250°C, and (2) the diffusion of As and Ga from the GaAs substrate occurs during the growth process.
Microcrystal Silicon Film of 1.7 eV Optical Band Gap
Authors: Fang P. H. , Bai Peiguang , Schubert C. C. , Kinnier J. H.
Published: November 2005

A prominent optical band gap of 1.7 eV has been observed in microcrystal silicon film prepared in vacuum at a substrate temperature of 625°C by electron beam evaporation.
Resistivity, Hall Mobility and Leakage Current Variations in Undoped Semi-Insulating GaAs Crystal Grown by LEC Method
Authors: Matsumura Takao , Emori Haruo , Terashima Kazutaka , Fukuda Tsuguo
Published: November 2005

The resistivity and Hall mobility (measured at 400 K) variations across undoped semi-insulating GaAs wafers obtained from the upper part of the LEC grown ingot have been measured and are compared with the dislocation density variation. It has been found that the resistivity is almost inversely proportional to the dislocation density and Hall mobility is proportional to the logarithm of the dislocation density. We have further measured the leakage current variation in comparison with the resistivity and dislocation density variation. Both the leakage current and resistivity show an M shaped variation across the wafers which have a W shaped dislocation density variation.
Anodic Dissolution Behaviour of Si- and Ti-Implanted Iron
Authors: Okabe Yoshio , Iwaki Masaya , Takahashi Katsuo , Yoshida Kiyota
Published: November 2005

Effects of silicon and titanium ion-implantations on anodic dissolution behaviour of iron have been investigated by multi-sweep cyclic voltammetry in acetate buffer solution (pH∼5), secondary ion mass spectrometry and scanning electron microscopy. Ion-implantations have been carried out with a dose of 1×1017 ions/cm2 at an energy of 150 keV at room temperature. It is found that electrochemical properties of Si+- and Ti+-implanted irons are more inert than that of pure iron. Anodic dissolution phenomena of ion-implanted irons are discussed in relation to the shape of an electrochemically corroded surface observed by SEM and to the concentration profiles of implanted atoms measured by SIMS.
A Novel Technique for Measuring the Frequency Deviation of Semiconductor Lasers Under Direct Modulation
Authors: Tsuchida Hidemi , Tako Toshiharu , Ohtsu Motoichi
Published: November 2005

A novel technique is proposed for measuring the frequency deviation of semiconductor lasers under direct modulation using a Michelson interferometer. This technique is applicable to a wide range of modulation frequency and does not require high-speed photo-detectors. The accuracy of the measurement is not reduced by the spectral line-width of lasers, the misalignment of the optical axes, or the depth of intensity modulation.
Observation of Lattice Defects in GaAs and Heat-treated Si Crystals by Infrared Light Scattering Tomography
Authors: Moriya Kazuo , Ogawa Tomoya
Published: November 2005

Most semiconductor crystals are transparent for infrared rays but some of them are difficult to study by X-ray methods if they are composed of heavy elements.
An infrared light scattering tomography, which is developed in this paper to characterize semiconductor crystals, successfully gives clear images of micro-defects in a heat-treated Si crystal and dislocation networks in a GaAs crystal grown by a horizontal Bridgman method.
Two-Dimensionally Collimated Output Beam from GaAlAs Diode Lasers with Two-Dimensional Distributed Bragg Reflectors
Authors: Uomi Kazuhisa , Yamanishi Masamichi , Suemune Ikuo
Published: November 2005

A stable and highly collimated output beam (≃1° with 2:1 aspect ratio) was obtained from a two-dimensional distributed Bragg reflector GaAlAs diode laser as a result of a large lasing internal spot (≃50 µmφ), which resulted from a widening in the gratings due to distributed Bragg reflection and the coupling out by the grating coupler. Optimization of the laser structure allowed room temperature operation with low threshold currents. Single longitudinal modes were observed in these two-dimensional oscillations.
Bias Sputtering of Superconducting Nb3Ge
Authors: Nakamura Kiko , Asano Hidefumi , Terada Akira
Published: November 2005

Crystalline growth of metastable, stoichiometric A15Nb3Ge on sapphire has been investigated through the use of bias sputtering. When the substrate holder was set at a constant potential, the A15 phase lattice parameter stayed near a constant value of 5.14 Å for the ordered, high-T
c A15Nb3Ge over a wide thickness range of 450–3500 Å. A superconducting transition onset at 17 K was obtained for 450 Å thick films. With a floating holder, on the contrary, ordered A15Nb3Ge was formed epitaxially on the expanded A15 lattice layers. It was surmised that bias-induced ion-bombardment facilitates ordered A15Nb3Ge growth.
Electron Dynamics and Strong Ion Beam Production in Magnetically Insulated Ion Diode Operated in Long Pulse Mode
Authors: Nakagawa Yoshiro
Published: November 2005

By an annular magnetically insulated ion diode operated in long pulse mode, total ion current of 5 kA and ion current density over 30 times the Child-Langmuir limit are achieved. Average length of electron drift by E×B force in the gap is measured to be about three times the gap length. Based on fundamental theory, the ion production efficiency is estimated by this length consistent with the experimental value (20%). The value of E×B current evaluated from this length is enough to change the applied magnetic field. It is predicted by the theory describing ion flow enhancement.
Microwave Plasma CVD System to Fabricate α-Si Thin Films out of Plasma
Authors: Kato Isamu , Wakana Shin-ichi , Hara Shinji
Published: November 2005

This study has been concerned with the development of a system to fabricate thin films by a microwave plasma chemical vapour deposition method while keeping the substrate out of the discharge plasma. Si thin films are fabricated in a deposition region using an improved coaxial line type microwave CW discharge tube without a silicon deposition on the discharge tube wall.
A very uniform Si thin film has been fabricated over a circle with a 10 cm diameter and the deposition rates are 50 to 400 Å/min. The structure of the fabricated films is amorphous and the optical band gap is 1.8 to 2.0 eV.
Determination of Integrated Reflecting Power of Silicon Crystal by Means of Mössbauer γ-Ray Diffraction
Authors: Kashiwase Yasuji , Minoura Masayuki
Published: November 2005

Integrated reflecting powers of the flat surfaces parallel to (111) planes of a Si crystal polished mechanically only and etched chemically further were determined by using 14.4 keV Mössbauer γ-rays from Co57 and its resonant absorber ahead of a position sensitive detector. The experimental values of the integrated reflecting powers of the crystal with chemically etched surface were close to those calculated on the theoretical basis of the model of absorbing perfect crystal.
Nb/Nb oxide/Pb Josephson Tunnel Junctions Fabricated Using CF4 Cleaning Process
Authors: Michikami Osamu , Katoh Yujiro , Yoshii Shizuka
Published: November 2005

Effects of an Ar and CF4 RF plasma mixture, in which the base electrode surface was cleaned prior to oxide barrier formation, on Nb/Nb oxide/Pb Josephson tunnel junction characteristics have been investigated. Good quality junctions with less leakage current (Vm=39.3 mV) and no knee at voltages just above the gap voltage have been obtained using the CF4 cleaning process (CFCP). It is speculated that the chemical etching reaction and a carbon layer generated on the cleaned Nb surface by CF4 plasma play an important role in achieving a cleaned based electrode surface free from damage and the formation of a good quality oxide tunnel barrier, respectively.
Electronic Properties of RF-Sputtered Unhydrogenated Amorphous Silicon-Germanium Alloy
Authors: Takano Yoshiki , Kitaoka Nobuyasu , Ozaki Hajime
Published: November 2005

The electronic properties of RF-sputtered unhydrogenated amorphous silicon-germanium binary alloy, a-Si
x
Ge1-x
, were investigated. In the intermediate region of the composition x, an enhancement of the density of states at the Fermi level was observed through variable-range hopping conduction, indicating a disorder. The optical energy gap was observed to vary approximately linearly with x. The effect of the compositional disorder was also observed in the B coefficient of the interband optical absorption.
Ultrasonic Behavior of Wood's Metal upon Melting and Solidification
Authors: Kamioka Hiroaki
Published: November 2005

The compressional and shear wave velocities in a multicomponent alloy, Wood's metal, were accurately determined by the pulse transmission method at temperatures between room temperature and 100°C. The melting point of Wood's metal was found to be 71.4°C, and the rates of temperature change upon heating and cooling were 1.887–0.063°C/min and 0.830–0.049°C/min, respectively. A large hysteresis loop in the relation between the sound velocity and temperature were observed around the melting point. The hysteresis depended strongly on the degree of supercooling, which was in turn affected by the rate of temperature change. The significance of the hysteresis loop in the melting-solidifying process is discussed by combining the present ultrasonic data with observations of the metal texture by metal-reflecting microscope.
Surface Defects on MBE-Grown GaAs
Authors: Suzuki Yoshifumi , Seki Masahiro , Horikoshi Yoshiji , Okamoto Hiroshi
Published: November 2005

The most common macroscopic defects in GaAs layers grown by MBE, i.e. oval defects, were studied. TEM observation shows that oval defects include stacking faults and that the crystalline quality is considerably inferior around these stacking faults. The successive optical microscopic observation of step-etched surfaces reveals that for an epitaxial layer with an oval defect density of more than 104/cm2, the majority of the oval defects originate in the epitaxial layer, while for an epitaxial layer with an oval defect density of less than 103/cm2, they originate at the interface between the epitaxial layer and the substrate. X-ray topography and observation of the dislocation etch pits clearly show that substrate dislocations are not responsible for the oval defects.
Investigation of Transport Properies in Pb1-xSnxTe Doped with Indium
Authors: Takaoka Sadao , Itoga Takashi , Murase Kazuo
Published: November 2005

The electrical resistivity and the Hall coefficient (R

H
) vs temperature (4.2K≦T≦300 K) in Pb1-x
Sn
x
Te/In (0.21≦x≦0.35) have been measured. In the semi-insulating region (x=0.30), a sign inversion of R

H
with respect to the magnetic field is observed at (60 K≦T≦100 K), and this is due to the coexistence of electrons and holes. From this phenomenon, the mobility ratio of electrons and holes has been determined for the first time in this system. Using these results, the composition and temperature dependence of the chemical potential in Pb1-x
Sn
x
Te/In have been determined systematically. The results can be explained qualitatively by the autocompensation model (the Anderson negative U model).
Simulation Study on Sloshing Ion Formation and Sustainment of Associated Potential Dip in a Plug Cell of GAMMA 6
Authors: Hoshino Motonobu , Tamai Hiroshi , Yatsu Kiyoshi , Katanuma Isao , Sawada Katuro , Miyoshi Syoichi
Published: November 2005

A Monte Carlo simulation on sloshing ion formation and the associated potential dip is described. It is shown in the GAMMA 6 tandem mirror machine that the sloshing ion distribution can be sustained for about 500 µs. The warm passing ions have a density depression in the region of the sloshing-ion density dip because of the acceleration due to the potential. This effect is included in the evaluation of the potential dip self-consistently. The potential dip is sustained for the duration of sloshing ion formation because the trapped cold ions obtain energy from the passing ions and escape from the potential dip.
Density Measurement of Helium Metastable Atoms in a Plasma by the Laser-Induced Fluorescence Method
Authors: Tsuchida Kazuki
Published: November 2005

Density profiles of helium metastable atoms in 23S and 21S levels have been measured in a plasma (n

e
∼1012 cm-3, T

e
∼7 eV, radius of the plasma column ∼1 cm) by the Laser-Induced Fluorescence Method (LIFM), where both quenching effects of fluorescence by plasma and characteristics of laser radiation are taken into account. The He(23S) metastable atoms are distributed in inverse proportion to the radius in the periphery of the plasma column (r>1 cm), while the profile of He(21S) metastable atoms has a gentle slope compared with that of He(23S) atoms. The difference in the density distributions is thought to be caused by the production of He(21S) atoms in the plasma periphery through the n1P (n≧2) levels due to optical excitation processes of He(11S) by resonance lines emitted from the plasma column.
Study of the Sloshing Ion Formation in a Minimum B Mirror Field
Authors: Tamai Hiroshi , Hoshino Motonobu , Yatsu Kiyoshi , Kusama Yoshinori , Kiwamoto Yasuhito , Kiyohara Yoichi , Sakasai Akira , Wakaida Ikuo , Inutake Masaaki , Sawada Katsuro , Miyoshi Syoichi
Published: November 2005

As a step towards the creation of a thermal barrier in a tandem mirror, formation of sloshing ion distribution is studied by oblique injection of neutral beams into one of the minimum B mirrors of GAMMA 6. Formation of the sloshing ion distribution is verified from the observations of the pitch angle distribution. The distribution is kept in a quasi-steady state, against relaxation of sloshing ions, to form a broad distribution. Potential dip is also observed in association with the sloshing ion distribution. The potential dip is sustained because the density of cold ions trapped in the dip is small.
Soft X-Ray Grating Spectrometer for Secondary-Excitation Using Synchrotron Radiation
Authors: Taniguchi Kazuo
Published: November 2005

A concave grating spectrometer of a new mounting mode for fluorescence X-rays in the region of 25 Å–300 Å excited by synchrotron radiation source has been constructed. This spectrometer is discussed from the stand point of (1) a ray tracing method, and (2) calibration of wavelength. The X-ray spectra for several sulfide compounds were obtained with this grating spectrometer using the synchrotron radiation as an excitation source.
Tunable Wavelength-Selection Characteristics of Multilayered Thin-Film Optical Separators Using Surface Acoustic Waves
Authors: Goto Nobuo , Miyazaki Yasumitsu , Akao Yasuo
Published: November 2005

Wavelength separation and tunable filtering characteristics in a multilayered optical coupler consisting of ZnS/Ta2O5/Nb2O5 films on a Y-cut LiNbO3 substrate are studied experimentally. By comparing the experimental data with theoretical analysis, the filtering pass bandwidth of the fabricated device is estimated to be approximately 24 Å with tuning sensitivity of 4.3×10-3 MHz-1 at the optical wavelength of 0.7950 µm. Wavelength separations are demonstrated for the wavelengths of 0.6328 µm and 0.7950 µm, and also for 0.7859 µm and 0.7950 µm. Hence the multi-wavelength laser beam guided in the device can be separated into its component wavelengths by controlling the SAW frequency.
Intervalence-Band Absorption in Relation to Auger Recombination in Laser Materials
Authors: Takeshima Masumi
Published: November 2005

A theory is presented for the intervalence-band absorption on the basis of the Green's function formalism, in which the electronic level broadening due to the phonon and ionized-impurity scatterings is taken into account. The theory is examined using experimental data of the absorption coefficient for p-type GaAs. The theory is then applied to In1-x
Ga
x
As
y
P1-y
, giving the absorption coefficients useful for analyzing laser operations. It is shown that temperature dependence of the absorption, assisted by the scattering processes, is much weaker than that of pure absorption which has been considered in almost all previous analyses. A close relation between the absorption cross section and the Auger coefficient is derived and it is shown that experimental values of the absorption cross section and the Auger coefficient can be explained with the present theory.
Electron Microscopic Study of Alloy Particles Produced by the Coalescence of Al Smoke and Cu Smoke
Authors: Kaito Chihiro
Published: November 2005

The structure of the particles in a mixture of Al and Cu smokes prepared by gas evaporation has been studied by electron microscopy in order to clarify the nature of the smoke particles. A mixed particle consisting of low- and high-temperature phase was observed near the evaporation sources. An Al particle containing a small amount of Cu showed many phases of the precipitation process. The appearance of the high and low temperature phases at different places in the smoke was consistent with the temperature of the particles in the smoke.
Highly Sensitive Optical Detector Using Superconducting Oxide BaPb0.7Bi0.3O3 (BPB)
Authors: Enomoto Youichi , Suzuki Minoru , Murakami Toshiaki
Published: November 2005

Highly sensitive optical detectors have been fabricated by using superconducting BaPb0.7Bi0.3O3 (BPB) thin films. Optical signals create quasi-particles and induce energy gap changes which can be detected by Boundary Josephson Junctions (BJJs) in the films. The sensitivity is 104 V/W in the 1.0∼10 µm wavelength range and they can respond up to 500 MHz. This device is useful as a detector in an optical communication system or an infrared spectrometer.
A WSi/TiN/Au Gate Self-Aligned GaAs MESFET with Selectively Grown n+-Layer using MOCVD
Authors: Imamura Kenichi , Yokoyama Naoki , Ohnishi Toyokazu , Suzuki Shoichi , Nakai Kenya , Nishi Hidetoshi , Shibatomi Akihiro
Published: November 2005

A WSi/TiN/Au gate self-aligned GaAs MESFET was formed using MOCVD. The WSi/TiN/Au gate acts as a selective growth mask for the n+-layer. This new process is demonstrated to be effective for reducing the gate resistance and source resistance of FETs simultaneously. The gate resistance, R
g, was 3.4 Ω (L
g=1.3 um, W
g=30 um) and was reduced one tenth compared to that of the WSi gate. A high-speed MSI and high performance microwave device can be obtained by using the WSi/TiN/Au gate self-aligned GaAs MESFETs.