bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Carrier Concentration Profiles for Heavily Si-Implanted Semi-Insulating GaAs
Authors: Sakashita Toshihiko , Tamura Akiyoshi , Yoshioka Yoshiaki , Onuma Takeshi
Published: November 2005

A dip in the carrier concentration profile at a depth of 0.2 µm has been observed when Si was ion-implanted into a semi-insulating GaAs with a dose of 5×1014 cm-2 at an energy of 150 keV with subsequent annealing at 850°C for 30 min without encapsulant. Such a dip was not observed when infrared rapid thermal annealing at 1000°C for 10 s was employed. SIMS and PL analyses revealed that the dip in the carrier profile was closely correlated with the damage or defects remaining after annealing and that such defects were essentially eliminated by infrared rapid thermal annealing at 1000°C.
Detailed Study of Si-H Stretching Modes in µc-Si: H Film through Second Derivative IR Spectra
Authors: Satoh Takashi , Hiraki Akio
Published: November 2005

Infrared absorption (IR) spectra corresponding to stretching modes of Si-H bondings in hydrogenated Si microcrystalline (µc-Si:H) film with such structures as SiH, SiH2, SiH3 and \rlap (–SiHm\rlap)–n [chain-like] were studied in detail by taking the second derivative modes. Two absorption peaks due to SiH on Si(111) and Si(110) surfaces of the microcrystalline grains in the film, respectively, near 2100 cm-1 were clarified and the presence of both the symmetric and asymmetric modes of stretching in SiH2 on Si(100) and SiH3 on Si(111) and Si(110) surfaces was assigned successfully.
NMR and ESR Studies on a-Si:H Prepared by Glow Discharge Decomposition of Si2H6
Authors: Kumeda Minoru , Komatsu Hiroshi , Shimizu Tatsuo , Fukuda Nobuhiro , Kitagawa Nobuhisa
Published: November 2005

A hydrogen incorporation scheme and the density of defects are investigated by means of NMR and ESR for hydrogenated amorphous Si films prepared by glow discharge decomposition of disilane gas. Both the high rf power of decomposition and the high substrate temperature bring the films with a low density of defects, because in these films the content of dispersed hydrogen effective for relaxing the structural strain is large in spite of the small total hydrogen content.
Photoluminescence from AlGaAs-GaAs Single Quentum Wells with Growth Interrupted Heterointerfaces Grown by Molecular Beam Epitaxy
Authors: Fukunaga Toshiaki , Kobayashi Keisuke L. I. , Nakashima Hisao
Published: November 2005

Photoluminescence measurements have been carried out for AlGaAs-GaAs single quantum well structures grown by molecular beam epitaxy. At both 77 and 4.2 K a few exciton lines are observed for single quantum wells grown with a few minutes growth interruption at heterointerfaces under As4 pressure. The energy splittings of these peaks well correspond to monolayer well width fluctuations. The full widths at half maximum (FWHM) of these peaks are much narrower than those of peaks obtained from no growth interruption samples. Wide FWHM with no growth interruption sample comes from the small lateral extent of fluctuations comparable to the exciton diameter. Monolayer growth steps are much diminished after a few minutes growth interruption due to the migration of surface atoms.
Boron Doping Effects in Lateral Solid Phase Epitaxy of Amorphous Si Films
Authors: Ishiwara Hiroshi , Tamba Akihiro , Yamamoto Hiroshi , Furukawa Seijiro
Published: November 2005

Lateral solid phase epitaxy (L-SPE) of boron (B) doped amorphous Si films onto SiO2 patterns was investigated. The L-SPE rate in B-doped films was found to be about 8 times higher than that in undoped films and the L-SPE length measured from the pattern edge was twice enhanced by the doping effect. It was also found that the L-SPE rate in B-doped samples is proportional to the amount of B atoms introduced in the Si film, if the maximum concentration of B atoms does not exceed the solid solubility limit in Si.
Linewidth Enhancement Factor in GaAs/AlGaAs Multi-Quantum-Well Lasers
Authors: Ogasawara Nagaatsu , Ito Ryoichi , Morita Ryuji
Published: November 2005

The linewidth enhancement factor α in GaAs/AlGaAs multi-quantum-well (MQW) lasers has been determined from the spontaneous emission spectra below threshold. It is demonstrated that the value of α in MQW lasers is appreciably smaller than that in conventional double heterostructure (DH) lasers because of the enhanced carrier-density-derivative of the optical gain.
Electron Spin Resonance Study of Boron Doped a-SiNx:H (x=0.07)
Authors: Nojima Hideo , Hayakawa Takashi , Narikawa Shiro , Ehara Shaw
Published: November 2005

The electron spin resonance (ESR) has been measured on boron doped a-SiN
x
:H (x=0.07). It is found that the spin density of neutral silicon dangling bonds in a-SiN
x
:H (x=0.07) decreases as the Fermi level shifts toward the mid gap by doping boron. This decrease of spin density is considered mainly due to the decrease of the dangling bond density by chemical or electrical compensation of four-fold coordinated nitrogen and boron.
Influence of Low-Energy Atomic Hydrogen on Argon-Implanted Silicon Schottky Barriers
Authors: Ashok S. , Giewont K.
Published: November 2005

Low-energy (0.4 keV), high-dose (∼1018 cm-2) H+ implantation into n-type and p-type Si previously implanted with Ar has resulted in unusual modification of the Si surface barrier. The complex interaction of these ions in Si has resulted in Al/p-Si Schottky diodes with an effective barrier height of 0.83 eV, the highest reported value for any metal/p-Si contact. The corresponding complementary influence of atomic hydrogen on n-Si is not seen, suggesting specific interactions between H and the dopant or the formation of a surface layer of hydrogenated amorphous silicon.
High Relaxation Oscillation Frequency (beyond 10 GHz) of GaAlAs Multiquantum Well Lasers
Authors: Uomi Kazuhisa , Chinone Naoki , Ohtoshi Tsukuru , Kajimura Takashi
Published: November 2005

Direct modulation bandwidth of GaAlAs multiquantum well (MQW) lasers with 5 nm-thick GaAs wells was investigated. It was experimentally found that relaxation oscillation frequency of MQW lasers is beyond 10 GHz, which is twice that of double heterostructure lasers. This result was confirmed by theoretical analysis.
Spin-Polarized Scanning Electron Microscope for Magnetic Domain Observation
Authors: Koike Kazuyuki , Matsuyama Hideo , Todokoro Hideo , Hayakawa Kazunobu
Published: November 2005

Spatial resolution of magnetic domain images obtained with a spin-polarized scanning electron microscope has been improved to a level of 1 µm for an iron sample. This value has been primarily obtained by using a field emission gun.
Polyvinyl Alcohol Film Coating Effect on Novolac-Based Positive Electron Resist Sensitivity in X-Ray Lithography in an Atmospheric Environment
Authors: Okada Koichi , Ohfuji Takeshi , Matsui Junji
Published: November 2005

The polyvinyl alcohol (PVA) film coating effect on novolac-based positive electron resist (NPR) has been studied in X-ray lithography using a Si X-ray source in an atmospheric environment. Extremely striking deterioration in NPR sensitivity was observed in an atmospheric environment compared with in vaccum. It was also found that the sensitivity deterioration was to a greater extent improved by using the PVA/NPR scheme.
AlGaAs/GaAs Multiquantum Well Lasers with Buried Multiquantum Well Optical Guide
Authors: Semura Shigeru , Ohta Tsuneaki , Kuroda Takao , Nakashima Hisao
Published: November 2005

Transverse mode stabilized AlGaAs/GaAs multiquantum well (MQW) lasers with buried MQW optical guide (MQW-BOG) have been fabricated utilizing Zn-diffusion-induced disordering of AlGaAs/GaAs MQW. Lasers with such an optical guide structure operate in the fundamental transverse mode up to an output power as high as 30 mW. A small kink is observed in the L-I curve at an output power exceeding 30 mW. Above the kink, a twin peak appears in the far-field pattern while a single peak appears in the near-field pattern. From these results, it is confirmed that the MQW-BOG laser acts as an index guided laser with partial gain-guided effect.
Characteristics of Heterojunction Consisting of Conducting Polymers of Polythiophene and Polypyrrole
Authors: Kaneto Keiichi , Takeda Shinji , Yoshino Katsumi
Published: November 2005

A rectifying heterojunction consisting of polythiophene and polypyrrole films was prepared by the electrochemical method. It shows the forward-reverse current ratio of larger than 50 at ±0.5 V. The junction characteristics at the interface of metallic polypyrrole and p-type polythiophene are found to be Schottky-like in large sense from I-V, C-V and photovoltaic measurements.
Compression of a Cylindrical Thin Electrode in a New Relativistic Electron Beam Diode
Authors: Mizui Jun-ichi , Sato Morihiko , Yonezu Hiroaki , Tazima Teruhiko
Published: November 2005

Compression of a cylindrical thin electrode is optically observed in a new coaxial diode (called the “Ring Pinch Diode”) in which an electron beam circularly pinches. In the positive polarity case of an inner cylindrical electrode, the pinched electron beam irradiates and compresses the cylinder. Compression dynamics are divided into an explosive and an ablative mode according to the electron stopping range. In the negative polarity case, the pinched electron beam produces a ring plasma on the outer electrode, and the inner cylinder is also compressed under the stagnation pressure produced by the expanding plasma.
Angle-Resolved Plane Wave X-Ray Topography
Authors: Ishikawa Tetsuya , Kikuta Seishi , Kohra Kazutaka
Published: November 2005

A new X-ray topographic scheme was constructed by using a three crystal diffractometer of the (+, -, +) parallel setting. The first, second and third crystals are used as the collimator, sample and analyzer, respectively. With this scheme a plane wave image of a dislocation was angularly analyzed and the diffracted wave selected by the crystal analyzer was recorded on a photographic plate. A minute difference in direction of the diffracted X-rays, which is responsible for the fine structures of the image, was topographically observed. The formation mechanism of defect images is discussed.
Control of Crystal Orientations in Lattice-Mismatched SrF2 and (Ca, Sr)F2 Films on Si Substrates by Intermediate CaF2 Films
Authors: Ishiwara Hiroshi , Kanemaru Seigo , Asano Tanemasa , Furukawa Seijiro
Published: November 2005

Crystal orientations of SrF2 and (Ca, Sr)F2 films on Si(100) and (111) substrates were controlled by intermediate CaF2 films which were grown on the substrates prior to growth of lattice-mismatched fluoride films. SrF2 films with good crystalline quality were grown epitaxially on the CaF2/Si(100) structure, though the SrF2 films directly grown on Si(100) were mainly composed of preferentially (111) oriented crystallites. Similarly, (Ca, Sr)F2 films on Si(111) changed from epitaxial films with internal boundaries between regular and rotationally twinned crystallites to single crystal ones by use of the intermediate CaF2 films.
X-Ray Photoelectron Spectroscopy Study of GaAs (001) and InP (001) Cleaning Procedures Prior to Molecular Beam Epitaxy
Authors: Contour J. P. , Massies J. , Saletes A.
Published: November 2005

The effect of chemical etching by H2S04/H202/H20 (5/1/1) mixtures and of mechanopolishing by bromine-methanol diluted solution on GaAs (001) and InP (001) substrates for molecular beam epitaxy (MBE) has been studied using X-ray photoelectron spectroscopy (XPS). The final rinse in running deionized water does not produce any passivating oxide layer on the substrate surface. Oxidation observed on GaAs and InP after these cleaning procedures occurs during substrate handling in air. The H2S04/H202/H20 mixture produces arsenic rich surface layers having an atomic ratio As/Ga of 1.15, whereas the bromine-methanol mechanopolishing leads to an arsenic or phosphorus depleted surface with atomic ratios As/Ga=0.7 and P/In=0.65.
200 kV Mass-Separated Fine Focused Ion Beam Apparatus
Authors: Shiokawa Takao , Kim Pil Hyon , Toyoda Koichi , Namba Susumu , Gamo Kenji , Aihara Ryuso , Anazawa Norimichi
Published: November 2005

A 200 kV mass-separated focused ion beam apparatus using alloy liquid metal ion sources has been developed. Focusing characteristics have been estimated by scanning ion microscope images of the metal mesh and the sputter etching pattern fabricated by the focused ion beam. A beam diameter smaller than 80 nm was obtained for Ga+ with 100 pA at 200 kV.
Heavily Si-Doped GaAs and AlAs/n-GaAs Superlattice Grown by Molecular Beam Epitaxy
Authors: Ogawa Masaki , Baba Toshio
Published: November 2005

Heavy Si doping of GaAs and AlAs/n-GaAs superlattice prepared by molecular beam epitaxy has been studied. By lowering the substrate temperature below 420°C during the growth, carrier concentrations of 1.8×1019 cm-3 with a perfect mirror surface morphology were realized for GaAs and AlAs/n-GaAs superlattice, respectively. The high carrier concentration is ascribed to the suppression of Si-Si pair formation by the low temperature growth procedure.
Measurements of Atomic Hydrogen-Density Profiles in the RFC-XX-M Machine Using Laser Fluorescence Spectroscopy at the Hα Transition
Authors: Muraoka Katsunori , Uchino Kiichiro , Itsumi Yoshio , Hamamoto Makoto , Maeda Mitsuo , Akazaki Masanori , Kawamoto Toshikazu , Kumazawa Ryuhei , Okamura Shoichi , Adati Keizō , Aoki Takashi , Fujita Hideki , Hattori Kazutoshi , Hidekuma Shigeru , Okubo Yoshimi , Sato Teruyuki , Garner Harold R. , Baker Dan R. , Price Harry D.
Published: November 2005

To assist in the study of the power balance in a linear confinement machine, atomic hydrogen-density profiles in plasmas of the RFC-XX-M device were measured using laser fluorescence spectroscopy tuned to the Balmer alpha line. Measured profiles showed marked decreases of neutral densities in the centre of the plasma, which are explained by charge-exchange and electron ionization pumping by the plasma. It is important to note that the neutrals are well burned out in the central cell, Nl/Ne \lesssim0.01. Further, charge-exchange losses are quantitatively evaluated and discussed from the neutral-density profiles and parameters of the plasma.
Emitter-Base Junction Size Effect on Current Gain Hfe of AlGaAs/GaAs Heterojunction Bipolar Transistors
Authors: Nakajima Osaake , Nagata Koichi , Ito Hiroshi , Ishibashi Tadao , Sugeta Takayuki
Published: November 2005

A current gain reduction with emitter-base junction size decrease is found in uniform base AlGaAs/GaAs heterojunction bipolar transistors (HBTs). This characteristic is analyzed using a model that takes into account a lateral diffusion of injected electrons, and is shown to be well explained by this model. The results show the importance of excess base leakage current due to minority carrier recombinations in the external bases of uniform base HBTs.
Flux-Flow-Type Josephson Linear Amplifier with Large Gain and Wide Linear Range
Authors: Nagatsuma Tadao , Enpuku Keiji , Iwakura Hiroaki , Yoshida Keiji
Published: November 2005

A linear amplifier using a flux-flow phenomenon in a long Josephson junction has been designed and tested by connecting a load resistance. The present experiment has demonstrated that a current gain of 500/W
s (1/µm) is obtained for the load resistance of 9 mΩ when an input signal is applied with a control line of width W
s (µm). An equivalent circuit of the amplifier has also been presented, which shows that the device is most suitable for current amplification with large gain in low impedance circuits.
Si Atomic-Planar-Doping in GaAs Made by Molecular Beam Epitaxy
Authors: Sasa Shigehiko , Muto Shunichi , Kondo Kazuhiro , Ishikawa Hideaki , Hiyamizu Satoshi
Published: November 2005

Si atomic-planar-doping in GaAs was studied with the use of molecular beam epitaxy. It was found that doped Si impurities are entirely activated with a sheet doping concentration of up to about 3×1012 cm-2. A heavy doping experiment in GaAs was conducted by repeating Si planar doping. The average electron concentration of the n+-GaAs layer was as high as 1.14×1019 cm-3 which is comparable to the highest value ever reported for Si-doped GaAs.
Cross Sectional Transmission Electron Microscopy of Zn Diffusion Induced Disordering of GaAlAs-GaAs Multiquantum-Well Structures
Authors: Ishida Koichi , Ohta Tsuneaki , Semura Shigeru , Nakashima Hisao
Published: November 2005

Zn diffusion induced disordering of a GaAlAs-GaAs multiquantum-well (MQW) structure has been studied by cross sectional transmission electron microscopy. The disordering is found to occur uniformly along the lateral direction within a transition region of about 0.2 µm. The narrow width of the transition region is explained by the steep Zn concentration gradient of the diffusion front.
Variable-Focus Liquid-Crystal Fresnel Lens
Authors: Sato Susumu , Sugiyama Akira , Sato Rumiko
Published: November 2005

Liquid-crystal lens-cells shaped like a plano-convex Fresnel lens with homogeneous alignment are prepared. Their focal length can be varied from the value f
e for an extraordinary ray to nearly f
o for an ordinary ray by applying an electric field across the cell. The response and recovery times within several seconds are attained in the liquid-crystal lenses. More transparent (\gtrsim80%) variable-focus liquid-crystal lenses are achieved in the double-layered structure of two identical liquid-crystal Fresnel lenses with a mutually orthogonal optic axis.
AC-Electroluminescent Device Having a ZnS:Mn Single Crystal Phosphor Layer
Authors: Hirabayashi Katsuhiko , Katoh Katsumi
Published: November 2005

A ZnS:Mn single crystal phosphor layer is prepared on a Si(111) substrate by EB-evaporation. AC-Electroluminescent (EL) cells having this ZnS:Mn single crystal phosphor layer have been shown to have a lower threshold voltage than AC-EL cells having a polycrystal phosphor layer on glass. The decrease in threshold voltage is considered to be due to the longer electron mean-free path.
MES-FETs Fabricated on Doped a-Si Films
Authors: Okamoto Kotaro , Shimaya Katsuhisa
Published: November 2005

P atoms are doped into a-Si films by varying the mole fraction of PH3 to SiH4 (M
P/S) while keeping the mole fraction of Ar to SiH4 at 11. MES-FETs are fabricated on doped a-Si films and g
m=1.3 ·10-4 mS/mm is obtained for those fabricated on films deposited at M
P/S=1.5 ·10-3. Effective mobility of 1.9 cm2/V·s is obtained from transfer conductance and pinch-off voltage of MES-FETs, which is about one order higher than that obtained from MIS-FETs.
Phase Diagram of the Nd-Fe-B Ternary System
Authors: Matsuura Yutaka , Hirosawa Satoshi , Yamamoto Hitoshi , Fujimura Setsuo , Sagawa Masato , Osamura Kozo
Published: November 2005

An experimental study of the liquidus projection in a phase diagram of the Nd-Fe-B ternary system has been carried out. In the Nd-poor region, it is found that two phases, Fe2B and Nd2Fe7B6(T2), coexist with the liquid. Two monovariant curves, L\rightleftharpoonsFe+Fe2B and L\rightleftharpoonsFe2B+T2, join and form the transition reaction, L+Fe2B\rightleftharpoonsT2+Fe. The end point of the liquid in the Nd-poor regions is the ternary eutectic point, L\rightleftharpoonsFe+Nd2Fe14B(T1)+T2. The T2 and Nd2FeB3(T3) phases simultaneously solidify from the liquid. In the Nd rich region. T1 phase, T2 phase and (Nd) solid solution solidify from the liquid at the end point of the liquid.
An Interpretation of Discrete Energy Loss in He+ Ion Scattering from W Surfaces Containing Oxygen
Authors: Shoji Fumiya , Hanawa Teruo
Published: November 2005

In ISS with He+ ions, a double peak spectrum is found for the W surface including oxygen. The double peak is due to the inelastic scattering process concerned. To interpret this inelastic process, characteristics of the peak are investigated by varying the incident energy and the impact angle. The loss peak separated by about 20 eV is interpreted as the re-ionization loss of the once Auger neutralized He ions.
Far-Infrared Magnetooptical Study of Semi-Insulating Gallium Arsenide: A New Model for the Metastable State of EL2
Authors: Ohyama Tyuzi , Nakata Hiroyasu , Otsuka Eizo
Published: November 2005

Measurements of the far-infrared magnetooptical absorption in various semi-insulating GaAs crystals have been carried out at 4.2 K under photo-excitation. Unexpected new features are 1) dipole formation of impurities in Cr- and In-doped crystals and 2) photo-quenching of the Zeeman absorption of shallow donors in LEC-grown crystals. Based on our experimental results, we propose a new model of a complex center consisting of a shallow donor drawing to its neighborhood the EL2 center that is raised to its metastable state.
Preliminary Experiment on Electron Beam Injection for Tokamak Current Drive
Authors: Tanaka Hitoshi , Ando Akira , Ogura Kazuo , Maekawa Takashi , Terumichi Yasushi , Tanaka Shigetoshi , Mohri Akihiro , Kubo Shin , Hasegawa Mitsuru , Narihara Kazumichi
Published: November 2005

Electron beams with moderate energies, 0.4 to 2 keV, were injected for 5 ms into a small tokamak WT-2 by using the plasma anode method. The injection into a currentless plasma with a density 2.5×1018m-3 at a toroidal field 1.1 T formed a toroidal current 4 kA, which was nine times the injected beam current. Additionally, an inductively produced toroidal current was sustained during the injection.
AlGaAs Window Stripe Buried Multiquantum Well Lasers
Authors: Nakashima Hisao , Semura Shigeru , Ohta Tsuneaki , Kuroda Takao
Published: November 2005

Transverse mode controlled high power AlGaAs lasers with a window stripe buried multiquantum well structure have been developed using the simple and reliable Zn-diffusion-induced disordering process. The maximum pulsed light output of the laser is 240 mW. The lasers operate in a fundamental transverse mode up to 100 mW. The threshold current and external differential quantum efficiency depend on the total window region length, because of large free carrier absorption in the Zn diffused window region. By controlling the diffusion depth and window region length, the lasers with low threshold current and high external differential quantum efficiency are realized.
Striations in Undoped Semi-Insulating LEC GaAs
Authors: Nakajima Masato , Katsumata Tohru , Terashima Kazutaka , Ishida Koichi
Published: November 2005

Striations in undoped semi-insulating GaAs grown by liquid encapsulated Czochralski (LEC) technique were revealed by photoetching with diluted AB etchant and X-ray transmission topography. The striations had two different periods; one with shorter period of about 30 µm was due to crystal rotation, and the other with longer period of about 300 µm was due to melt convection. The formation of the striations in undoped semi-insulating GaAs was ascribed to stoichiometric inhomogeneity.
High Frequency Time Modulation of Neutrons by LiNO3 Crystals with Surface Acoustic Waves Excited under the Diffraction Condition
Authors: Takahashi Toshio , Granzer Erwin , Tomimitsu Hiroshi , Kikuta Seishi , Doi Kenji
Published: November 2005

High frequency time modulation of neutrons was investigated by using Y-cut LiNbO3 crystals with surface acoustic waves excited. A double crystal arrangement of (+, -) parallel setting was used for 030 symmetric Bragg-case reflections. Synchronized standing waves with a resonance frequency of 14.26 MHz were excited on the both crystals. Variation of the diffracted intensity with phase difference between two standing waves was studied. The result showed an intensity change of diffracted neutrons with twice the resonance frequency.
LPE Growth of Lattice-Matched InGaAsP on GaAs0.69P0.31 Substrates and Low Threshold Current Density Operation of Visible InGaAsP DH Lasers
Authors: Fujimoto Akira , Watanabe Hideaki , Takeuchi Masashi , Shimura Mikihiko
Published: November 2005

Lattice-matched InGaAsP epitaxial layers with various energy band gaps (E
g=1.874–2.115 eV) have been grown on (100)GaAs0.69P0.31 substrates by a ramp cooling liquid phase epitaxial (LPE) method. Energy band gaps and crystal compositions were determined by photoluminescence and double-crystal X-ray diffraction. Double-heterostructures were successfully grown and lased under a pulsed condition with low threshold current density (J
th=2.21 kA/cm2) and short wavelength (λp=659 nm) at room temperature. The highest external quantum efficiency was 21.7%/facet.
Nanosecond Switching in Thin Fims of Vinylidene Fluoride/Trilluoroethylene Copolymers
Authors: Furukawa Takeo , Matsuzaki Hisashi , Shiina Masahiro , Tajitsu Yoshiro
Published: November 2005

High-field switching characteristics have been investigated in the spin-coated thin films of vinylidene fluoride/trifluoroethylene copolymers containing 52, 65, 73 mol% of the former. The switching times of three copolymers are identical af fields from 150 to 500 MV/m, following an exponential dependence on the reciprocal field. The observed fastest switching time is 100 nsec which is shorter than the dielectric relaxation time associated with crystalline dipole motions. The result indicates that total reorientation of crystalline dipoles occurs faster than the correlation time of their natural fluctuations.
Molecular Orientation in the Physical-Vapour-Deposited Thin Films of Calcium Stearate
Authors: Miki Tomoharu , Inaoka Kimio , Sato Kiyotaka , Okada Masakazu
Published: November 2005

Molecular orientation of the physical-vapor deposited thin films of calcium stearate was observed by a transmission electron microscopy. We found that the thin films consisting of the long chain molecules normal to the substrate can be formed either by decreasing the deposition rate or by increasing the temperature of substrate. This means that the normally-oriented thin films of the long chain compounds can be achieved by the physical-vapor-deposition at a very low deposition rate.
The observations of the step morphologies showed that the growth of normally-orientated calcium stearate films occurred by a spiral growth mechanism and by a birth and spread mechanism at lower and higher supersaturations, respectively.
Observation of X-Ray Standing Wave Field during Bragg Reflection in Multilayer of Lead Stearate
Authors: Iida Atsuo , Matsushita Tadashi , Ishikawa Tetsuya
Published: November 2005

Evidence for the excitation of an X-ray standing wave field during Bragg reflection in a Langmuir-Blodgett multilayer (220 monolayers) of lead stearate was obtained by measuring the intensity of PbLα fluorescence emitted from the stearate film as a function of glancing angle of monochromated (13.4 keV) synchrotron X-rays. A dip and a hump were observed in the fluorescence intensity curve just below and above the Bragg peaks corresponding to the first and second order reflections. This feature is reproduced in calculations which take multiple scattering of X-rays into account.
Application and Characteristics of Conducting Polymer as Radiation Shielding Material
Authors: Yoshino Katsumi , Tabata Munehiro , Kaneto Keiichi , Ohsawa Toshiyuki
Published: November 2005

Conducting polymers with high electrical conductivity like doped polypyrrole are used successfully as radiation shielding meterials. They are especially effective to shield an electric field with an attenuation higher than 30 dB in the range of 3 MHz–300 MHz with doped polypyrrole of 35 µ thickness, bu not effective for shielding a magnetic field with attenuation less than 10 dB in the same range.
Formation of Mono-Dispersed Fe3O4 Fine Particles
Authors: Oda Masaaki , Saegusa Norio
Published: November 2005

Mono-dispersed single crystal Fe3O4 fine particles with an average diameter of 240 Å and distribution full width at half maximum of 60 Å are prepared using an improved gas evaporation method.
Local Temperature Rise during Laser Induced Etching of Gallium Arsenide in SiCl4 Atmosphere
Authors: Takai Mikio , Nakai Hiroyuki , Tsuchimoto Jun'ichi , Gamo Kenji , Namba Susumu
Published: November 2005

Localized etching of GaAs using an argon laser beam in an SiCl4 atmosphere has been performed for various laser powers to investigate the threshold power, i.e., the minimum local temperature, for pyrolytic etching. Local temperature rise during laser induced etching was measured by the peak shift of in situ photoluminescence and was also estimated by solving the three dimensional heat equation. It was found that the threshold power for pyrolytic etching at an SiCl4 pressure of 76 Torr was about 0.25 W, turning out to be about 190°C, which was in good agreement with the calculated temperature.
Misfit Dislocation Generation for MBE Grown GaAs on In-Doped LEC-GaAs Substrates
Authors: Shinohara Masanori , Ito Tomonori , Yamada Kohji , Imamura Yoshihiro
Published: November 2005

Nearly dislocation-free indium-doped LEC-GaAs crystals are applied to substrates for MBE-GaAs growth. Misfit dislocation generation at the epi-layer/substrate interface is found by electron beam induced current method. The critical trhickness for generating misfit dislocations agrees with theoretical predictions. The relationship between the critical thickness and indium concentration is deduced. This result suggests that misfit dislocations generate at small epi-layer thickness (< 1.5 µm) when the indium concentration is more than 5×1019/cm3.
Redox States and Absorption Losses of 3d Transition Metals in Fluoride Glasses
Authors: Nakai Tetsuya , Mimura Yoshinori , Shinbori Osamu , Tokiwa Hideharu
Published: November 2005

The effect of oxidizing and reducing atmospheres (Ar and NF3) on the valency states of several 3d transition metals (Cu, Cr, Mn, Ni and Co) in fluoride glasses and on their absorption losses have been investigated. NF3 atmosphere processing reduces the absorption loss due to chromium ions, but increases the loss due to copper ions.
Structure of the Commensurate Phase P'' of Wüstite Fe0.902O Studied by High Resolution Electron Microscopy
Authors: Ishiguro Takashi , Nagakura Shigemaro
Published: November 2005

Atomic level observations have been made of the commensurate phase P'' of Fe0.902O. In the ideal state, the crystal structure is monoclinic with lattice parameters a=b=\frac{5}{2} √2a
0, c=5a
0 and γ=90^°, and belongs to the space group P21/m. Here, a
0 is the lattice parameter of the fundamental cell taking the NaCl type of structure. The unit cell contains four iron vacancy clusters, each of which is made of two vacancy tetrahedra with a common edge and contains no tetrahedral iron atoms. This ideal structure is not usually realized in a real crystal, where stacking disorders in the cluster layers are successively introduced and in some cases the cluster itself is heavily deformed.
Observation of X-Ray Diffraction Spots from the (√3 ×√3)R30° Bi Structure on the Si(111) Surface under the Condition of Large Incidence Angle
Authors: Takahashi Toshio , Takayama Isamu , Ishikawa Tetsuya , Ohta Toshiaki , Kikuta Seishi
Published: November 2005

X-ray diffraction intensities from the (√3 ×√3)R30° Bi structure on the Si(111) clean surface were measured in an experimental geometry similar to that of LEED. Two diffraction spots of 1/3, 1/3 and 2/3, 2/3 were observed at the scattering angle of 133° for X-rays with the wavelength of 1.76 Å. A silicon wafer about 5 µm thick was used to reduce the background scattering from the bulk crystal.
Inhomogeneity of Resistivity in In-Doped Dislocation-Free Semi-Insulating LEC GaAs
Authors: Miyairi Hiroo , Inada Tomoki , Obokata Takeshi , Nakajima Masato , Katsumata Tōru , Fukuda Tsuguo
Published: November 2005

In-doped dislocation-free semi-insulating GaAs crystals were prepared from various melt compositions and measurement of resistivity distributions and infrared absorption at 1 µm were carried out. Inhomogeneity of resistivity, both along the radial and longitudinal directions, was observed even in some dislocation-free crystals. This inhomogeneity strongly depends on melt composition, and is mainly due to non-uniform distribution of stoichiometry-related defects revealed by infrared absorption measurement.
Low-Temperature Thermal-Oxidation of Amorphous-Silicon and Its Application to Amorphous-Silicon MOS Transistors
Authors: Uchida Yasutaka , Ikegami Takashi , Matsumura Masakiyo
Published: November 2005

A new low-temperature method of thermal-oxidation for amorphous-silicon has been proposed, and preliminary experimental results on its application to amorphous-silicon MOS transistors are presented. The resistivity of the oxide was over 1014 Ωcm and the field-effect mobility deduced from the saturation region of the transistor characteristics was 0.003 cm2/Vs.
Effect of Localized Recombination Planes on Minority-Carrier Diffusion Length in Silicon Solar Cells
Authors: Shimokawa Ryuichi , Hayashi Yutaka
Published: November 2005

The spatial variation of minority-carrier diffusion length in the vicinity of a stress-relieved boundary surface in monocrystalline and semicrystalline silicon solar cells has been measured for the first time by the scanned monochromatic light beam induced current (MBIC) technique with a very small spot size (2 µmφ) and 750–1050 nm long-wavelength light beam. The technique we developed uses a short-arc xenon lamp source with line spectra. It was found that the effect of a boundary surface extended beyond the distance of minority-carrier diffusion length. Furthermore, it was indicated that the output currents of semicrystalline silicon cells could be described by a monocrystalline device model using the concet of the effective minority-carrier diffusion length.
Preparation of High Purity a-Si:H Films and Their Light Soaking Effects
Authors: Muramatsu Shin-ichi , Nakamura Nobuo , Matsubara Sunao , Itoh Haruo , Shimada Toshikazu
Published: November 2005

The preparation of high purity a-Si:H films is discussed in order to improve material quality and to reduce the Staebler-Wronski (S-W) effect. This letter presents the preparation technique and its relationship to the S-W, or light soaking effect. By using a hot-wall type symmetric-plasma CVD system and high rate deposition method, contaminant impurity levels in a-Si:H films are significantly reduced. Photoconductivity measurements of the films show that light soaking effects are reduced with oxygen content decreases to as low as 4×1017/cm3.
Shock-Loading Effect on Molybdenum Nitride Prepared in Ammonia Gas
Authors: Kagawa Masahiro , Ono Tomoshige , Fukuoka Kiyoto , Syono Yasuhiko , Ikebe Manabu , Muto Yoshio
Published: November 2005

Shock loading effect on the hexagonal δ-MoN prepared by nitriding metal molybdenum in ammonia gas was investigated. δ-MoN decomposed to form γ-Mo2N with increasing shock pressure. The porosity of the specimens showed no effect on the amount of the formed γ-Mo2N, indicating that the decomposition reaction is predominantly due to the pressure effect at shock compression. The specimens shocked to 39 GPa had newTc's at 5.8 and 5.0 K besides 13 K of δ-MoN. At 50 GPa δ-MoN converted to γ-Mo2N completely and the lattice constant of γ-Mo2N became smaller, thus implying the release of nitrogen. No B1 type MoN was observed up to this pressure region.
Crystallization Characteristics of ZrF4-Based Fluoride Glasses in Cooling and Reheating Processes
Authors: Kanamori Terutoshi , Takahashi Shiro
Published: November 2005

Crystallization kinetics of ZrF4-based fluoride glasses in melt-cooling and reheating processes have been investigated by calorimetry. Critical cooling rates for glass-formation are estimated using the relation between undercooling and cooling rate. Kinetic parameters of crystallization in reheating are obtained just above deformation temperatures using the Avrami equation. It has been found that a ZrF4-BaF2-LaF3-YF3-AlF3-LiF glass shows high stability against crystallization in both cooling and reheating. An optical fiber has been fabricated from this glass, having a loss of 3.8 dB/km at a wavelength of 2.55 µm.
Temperature Dependence of Reverse Current in Be Ion Implanted InSb p+n Junctions
Authors: Fujisada Hiroyuki , Kawada Masakuni
Published: November 2005

Temperature dependence of the reverse current in Be ion implanted InSb p+n junctions is studied. Results indicate that the generation-recombination is a dominant mechanism for the reverse current in metallurgical junctions. A combination of tunneling and thermal excitation via surface states is proposed as a surface conduction mechanism in field induced junctions.
Low Interface Recombination Velocity in GaAs-(Al, Ga)As Double Heterostructures Grown by Metal Organic Vapour Phase Epitaxy
Authors: Hooft G. W.'t , Leys M. R. , Roozeboom F.
Published: November 2005

The interface recombination velocity in GaAs-(Al, Ga)As double heterostructures has been investigated at room temperature. The structures were grown by metal organic vapour phase epitaxy using the so-called “chimney” reactor. With the technique of photoluminescence decay, interface recombination velocities as low as 53 cm/s were found for n-isotype structures. For injection laser structures the lowest interface recombination velocity obtained was about 100 cm/s at high injection levels as deduced from luminescence efficiency measurements.
Measurement of Field-Emission Current-Fluctuations by Digital Autocorrelation of Electron-Counting
Authors: Okano Tatsuo , Honda Tohru , Tuzi Yutaka
Published: November 2005

A new method of field-emission current-fluctuation analysis is presented. Digital autocorrelation of counting-fluctuations of field-emitted electrons is discussed on the basis of the theory of photon-counting fluctuations. The measurement of the digital autocorrelation function is made by using a pulse-counting system of field-emitted electrons and a microcomputer. The surface diffusion of Xe adsorbed on a (110) vicinal plane of W is studied with the present method. Measured digital autocorrelation function agrees well with the theory and surface diffusion coeffcient of 2.9×10-7cm2/s is obtained at 78 K.
Critical Current Density in Superconducting Nb3Ge and NbN Films at Fields up to 30 T
Authors: Suzuki Mitsumasa , Anayama Takeshi , Watanabe Kazuo , Toyota Naoki , Kobayashi Norio , Noto Koshichi , Muto Yoshio
Published: November 2005

The superconducting critical current densities J
c of Nb3Ge and NbN films prepared by sputtering have been studied in fields up to 30 T for the perpendicular field direction H⊥ to the film surface and up to 23 T for the parallel field direction H//. The Nb3Ge film exhibits J
c exceeding 1 ×105(1 ×104) A/cm2 in fields below 21(30) T for H⊥ and below 23 T for H//. The J
c of the NbN film for H⊥ is higher than 1 ×105 A/cm2 in fields below 21 T, while that for H// is much reduced. Their pinning properties and upper critical fields H
c2 are presented.
Fluxon Transfer Device
Authors: Sakai Shigeki , Akoh Hiroshi , Hayakawa Hisao
Published: November 2005

A fluxon transfer device, consisting of a Josephson transmission line partially having a shunt resistor, is fabricated. Experiments are performed using a Josephson sampler. The results show that a fluxon stops at the resistively shunted portion and is moved again by applying a drive current, and that the stopping fluxon does not move for at least ∼100 µs, i.e., the stopping state is stable. The bit transfer time is as fast as ∼25 ps.
(InAs)1(GaAs)1 Layered Crystal Grown on (100)InP by MOCVD
Authors: Fukui Takashi , Saito Hisao
Published: November 2005

The crystal growth process is investigated for a (InAs)1(GaAs)1 layered crystal (LC) grown on (100) oriented InP by metallorganic chemical vapor deposition (MOCVD). It is shown that substrate misorientation strongly affects the layered crystal properties. Macroscopic growth steps are observed when these LCs are grown on (100) vicinal oriented InP substrates (α=2^°). Furthermore, the superlattice orientation is in the (100) direction and does not reflect the original substrate surface. The results indicate that preferential layer nucleation of InAs/GaAs takes place along (100) singular surfaces.
Influence of Melt Composition on Uniformity of Electrical Properties in Semi-Insulating LEC GaAs
Authors: Obokata Takeshi , Katsumata Tooru , Fukuda Tsuguo
Published: November 2005

Influence of melt composition on uniformity of resistivity and mobility in semi-insulating, undoped GaAs grown by liquid encapsulated Czochralski technique was investigated in detail. Microscopic two-dimensional resistivity distribution was measured using the three-electrode guard method, and Hall mobility was measured by the van der Pauw method. Relatively uniform, four fold symmetric resistivity distribution was observed in crystals grown from stoichiometric or slightly As-rich melt, whereas very significant fluctuations in resistivity were found in crystals grown from Ga-rich or heavily As-rich melt. High and rekatively uniform mobility along both axial and radial directions is obtained at near stoichiometric melt compositions.
Epitaxial Growth of GaN1-xPx (x \lesssim0.04) on Sapphire Substrates
Authors: Igarashi Osamu , Okada Yasumasa
Published: November 2005

Gallium nitride phosphide (GaN1-x
P
x
) was epitaxially deposited on (0001) sapphire substrates by the vapor phase reaction of the Ga-NH3-PCl3-N2 system. The growth rate was 0.80 µm/hr at 1100°C and decreased with decreasing growth temperature. Composition x increased with decreasing growth temperature. The maximum composition x obtained was about 0.04 at 1050°C.
Planar DC SQUID with a Damping Resistor
Authors: Ohkawa Norio , Noguchi Takashi , Hamanaka Koichi
Published: November 2005

A planar dc SQUID (Superconducting Quantum Interference Device) with a damping resistor is made, and its current-voltage characteristics and output voltage as a function of applied magnetic flux are studied. As the result of inserting a damping resistor parallel with the self-inductance of the SQUID loop, self-induced resonance dc components in the current-voltage characteristics are eliminated, and the amplitude Δ
V of the output voltage increases. Consequently, the value of the flux-to-voltage transfer function also increases compared with that of a dc SQUID without a damping resistor.
Single Crystal Measurements of Anisotropy Constants of R2Fe14B (R=Y, Ce, Pr, Nd, Gd, Tb, Dy and Ho)
Authors: Hirosawa Satoshi , Matsuura Yutaka , Yamamoto Hitoshi , Fujimura Setsuo , Sagawa Masato , Yamauchi Hiroshi
Published: November 2005

The first order anisotropy constants K
u1 of the recently found tetragonal rare earth-iron borides R2Fe14B (P42/mnm) have been measured for R=Y, Ce, Pr, Nd, Gd, Tb, Dy and Ho in a magnetic field up to 1600 kA/m from 4.2 K to about 600 K on single crystal samples.
8 nm Wide Line Fabrication in PMMA on Si Wafers by Electron Beam Exposure
Authors: Emoto Fumiaki , Gamo Kenji , Namba Susumu , Samoto Nobuhiko , Shimizu Ryuichi
Published: November 2005

The ultimate limit of electron beam lithography in practical samples, e.g., thick PMMA on bulk Si substrate, was investigated in both experiment and theory. For this, the nanometer electron beam lithography system (NSF-1) was used to perform nanometer structure patterning. Monte Carlo calculation with secondary electron generation included was done to simulate the experiment. Eight nanometer wide lines with 100 nm period were delineated in 230 nm thick PMMA on a bulk Si, probably attaining the ultimate limit of electron beam fabrication. This has also been supported by evaluation based on the Monte Carlo simulation.
Proposed Planar-Type Amorphous-Silicon MOS Transistors
Authors: Uchida Yasutaka , Matsumura Masakiyo
Published: November 2005

Novel planar-type amorphous-silicon metal-oxide-semiconductor transistors have been proposed and their features have been demonstrated. The gate insulator of silicon-dioxide grown inside the original amorphous-silicon layer makes transistor characteristics highly stable. The source and drain of micro-crystal silicon make the fabrication process simple and the parasitic elements small. The on-current of the prototype transistor was extrapolated to decrease to one-half of its initial value 1010 years after the application of dc bias. The on-off current ratio was about 106 and no voltage offset was observed. The field-effect mobility was 0.6 cm2/Vs.
A Simple Calculation of the DX Center Concentration Based on an L-Donor Model
Authors: Tachikawa Masami , Mizuta Masashi , Kukimoto Hiroshi , Minomura Shigeru
Published: November 2005

The DX center concentration in Al
x
Ga1-x
As which depends on composition and hydrostatic pressure has been calculated, based on a model wherein the donor level which is associated with the L conduction band forms the DX center. The calculation shows good agreement with the results of observation. The present model can be applied to a similar center observed in GaPAs. The possibility of DX center formation in other III-III'-V and III-V-V' ternary alloy systems has also been pointed out.
Reduced Carbon Contamination in OMVPE Grown GaAs and AlGaAs
Authors: Kobayashi Naoki , Makimoto Toshiki
Published: November 2005

Trimethyl and triethyl organometallic source materials were compared through the investigation on the optical and electrical properties of undoped GaAs and AlGaAs layers grown from these materials. Our experimental results indicate that the carbon contamination in the grown GaAs and AlGaAs is greatly reduced when triethyl organometallic compounds are used insteads of trimethyl organometallic compounds.
Relationship between Scattering Loss and Oxygen Content in Fluoride Optical Fibers
Authors: Mitachi Seiko , Sakaguchi Shigeki , Yonezawa Hiroki , Shikano Kohji , Shigematsu Toshio , Takahashi Shiro
Published: November 2005

To clarify the cause of scattering loss in fluoride optical fibers, oxygen content in fibers having various loss values is analyzed by activation analysis using a cyclotron. It is found that fibers with higher loss contain a higher oxygen content. It is concluded that oxygen tends to cause scattering loss in fluoride optical fibers.
The Role of Hydrogen in the Staebler-Wronski Effect of a-Si:H
Authors: Ohsawa Michio , Hama Toshio , Akasaka Toshiaki , Ichimura Takeshige , Sakai Hiroshi , Ishida Sueshige , Uchida Yoshiyuki
Published: November 2005

We have studied the effects of hydrogen concentration and hydrogen configuration on the light-induced change, called Staebler-Wronski effect, in a-Si:H. A strong correlation is found between the light-induced spin density and the fractional hydrogen content evolved at low annealing temperature. The light-induced defects are supposed to be created through the breaking of weak Si-Si bonds in the regions containing clustered SiH or SiH2 bonds.
An/TaN/WN/GaAs Structure Schottky Gate Formation for Self-Aligned GaAs MESFET
Authors: Yamagishi Haruo , Miyauchi Masayoshi
Published: November 2005

An Au/TaN/WN/GaAs structure Schottky gate forming process was investigated for self-aligned microwave GaAs MESFET. Multi-layers of transition metal nitride were formed by reactive rf sputtering. Good Schottky contacts were obtained for the Au/TaN/WN/GaAs system even after a high-temperature rapid infrared lamp annealing for ion implantation. A gate forming process for self-aligned GaAs MESFET was developed using the Au/TaN/WN multi-layers gate. The self-aligned GaAs MESFET with 0.7 µm gate length showed a noise figure of 1.7 dB with an associated gain of 7.3 dB at 12 GHz.
Improved Performance of the Pulsed Copper-Vapor-Laser; CuCl-Vapor-Laser with a Compact Device by Applying an AC Continuous-Glow-Discharge
Authors: Saito Hiroshi , Taniguchi Hiroshi , Ohgami Kosei
Published: November 2005

An additional continuous-glow-discharge was applied to the aperiodic pulsed CuCl-vapor-laser. The experimental results exhibited an increase of up to 60% the laser-output average power at the maximum point, an increase of 1.5 times the peak power and pulse repetition frequency, and twice the pulse width in the laser oscillation against the laser without the continuous-glow-discharge. Further, the additional technique led the CuCl-vapor-laser to operate in the higher operating-temperature region.