bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Surface Composition during ECR Discharge Cleaning in JFT-2M
Authors: Matsuzaki Yoshimi , Ohtsuka Hideo
Published: November 2005

Surface composition on a molybdenum sample has been observed during ECR discharge cleaning (ECR-DC) by Auger electron spectroscopy in JFT-2M. ECR-DC reduces oxygen levels to one-thrid of those before exposure within thirty minutes, and the molybdenum concentration increases up to a factor of three during ECR-DC. Carbon levels decrease once, then increase gradually. In the later phase Auger line shapes are similar to pure carbon. Sulfur, which appears under 120°C baking, surfaces from the stainless steel of the chamber as a result of the baking, and is sputtered by plasmas and deposited on the sample.
Tunneling Current in a-Si:H/a-Si1-xCx:H Multilayer Structures
Authors: Yoshimoto Masahiro , Du Kai-Ying , Fuyuki Takashi , Matsunami Hiroyuki
Published: November 2005

Tunneling current in a-Si:H/a-Si1-x
C
x
:H multilayer structures is observed at room temperature for the first time. The effective barrier height for tunneling is estimated to be 0.577 eV in a multilayer structure consisting of a-Si1-x
C
x
:H with an optical energy gap of 3.0 eV and a-Si:H. The effective barrier height and the value of tunneling current can be varied by changing the optical energy gap of a-Si1-x
C
x
:H.
GaAs Atomic Layer Epitaxy by Hydride VPE
Authors: Usui Akira , Sunakawa Haruo
Published: November 2005

GaAs atomic layer epitaxy is demonstrated in hydride vapor phase epitaxy by a dual-grown-chamber method. GaAs substrate is alternatively exposed to GaCl and As4 gases by transferring the substrate between two chambers. The growth rate was examined for differing growth conditions and was found to depend only on substrate transfer cycles. Furthermore, the present method can be applied to selective growth.
High Resolution Electron Microscopy of Composite Films of Gold and Magnesium Oxide
Authors: Nagao Masaru , Tanaka Nobuo , Mihama Kazuhiro
Published: November 2005

Composite films of gold and magnesium oxide are prepared by a simultaneous vacuum deposition technique. An important feature of the films is that gold is grown epitaxially and separately with the size of 1 to 3 nm inside (001) and (11̄0) magnesium oxide films about 20 nm in thickness. The structures of the composite films are studied by high resolution electron microscopy. The results suggest that the crystallites are embedded without strain in the matrix. The resistance property of the films is also measured by the four-probe method.
Preparation of Free γ-Iron Particles Quenched to Room Temperature
Authors: Kusunoki Michiko , Ichihashi Toshinari
Published: November 2005

A smoke of α-iron particles was produced by evaporation and subsequent condensation of iron in an atmosphere of argon. The smoke thus produced was introduced into a furnace at about 1000°C, where the γ-phase was stable. It was then blown against a surface cooled by liquid nitrogen. The smoke particles deposited there were examined at room temperature by electron diffraction and electron microscopy. It was proved that about 10% of the deposited particles (diameter, 500 Å ) were of the γ-phase.
Effects of In Doping on Cr-Related Luminescence in GaAs
Authors: Fujiwara Yasufumi , Kita Yasushi , Tonami Yoshiyuki , Nishino Taneo , Hamakawa Yoshihiro
Published: November 2005

We have investigated effects of In doping on the Cr-related luminescence lines in In, Cr-codoped GaAs and observed for the first time new Cr-related luminescence lines in addition to the well-known Cr–VAS zero-phonon line. The peak position of the Cr–VAS line in GaAs:In:Cr shifts slightly towards the lower-energy side and the half width is about five times broader than in the normal GaAs:Cr. These Cr-related luminescence lines have not been observed for GaAs:Al:Cr. Analysis of a series of the results of luminescence measurements for GaAs:In:Cr shows these newly observed Cr-related luminescence lines to be originated from a complex involving a Cr–VAS pair influenced by the existence of In in the second-nearest neighbors of the Cr atom in GaAs.
Origins of Midgap Electron Traps in Plastically Bent GaAs1-xPxTernary Alloys
Authors: Chino Ken'ichi
Published: November 2005

Electron traps in plastically bent VPE n-GaAs1-xPx(0≤x≤1) have been investigated using DLTS. While EL2 is dominant atx\lesssim0.5, two additional levels, one a midgap (EP1) and the other a deeper (EP2) level, dominate atx\gtrsim0.55. The energy level of EP1 atx=1.0 is in good agreement with that of the antisite PGadefect level in GaP estimated using ESR studies. EP2 energy levels have little dependence onx. EP1 as well as EL2 shows alloy broadening in DLTS spectra while EP2 remains unchanged. These findings indicate that EL2 and EP1 are due to antisite AsGaand PGadefects, respectively. EP2 is attributable to group V atom site defects.
Selective Deposition of Silicon Oxide and Its Application
Authors: Awaya Nobuyoshi , Arita Yoshinobu
Published: November 2005

This paper presents the results of an investigation on selective deposition of silicon oxide using poly-perfluoro-alkylacrylate (PPFAA) which has a significantly low surface energy. Under the condition that silicon oxide film can be deposited on Si, SiO2 and OFPR resist, no deposition is observed on PPFAA. This technique is successfully applied to the formation of fine patterns having a minimum dimension of 0.1 µm.
Hybrid Orbital Energy for Heterojunction Band Lineup
Authors: Hasegawa Hideki , Ohno Hideo , Sawada Takayuki
Published: November 2005

It is shown that the alignment of the hybrid orbital energy, EHO, is required at the heterojunction interfaces. The locations of EHO are tabulated for AlAs, GaP, GaAs, InP and InAs. The matching of EHO reproduces remarkably well the valence band discontinuity observed experimentally. An interpretation based on a simple thermodynamic consideration is given to explain why matching of EHO is required at the heterojunction interface, which involves inevitable formation of interface dipole as opposed to Tersoff's quantum dipole theory.
Hydrogenated Amorphous Silicon Germanium Alloys Prepared by Triode rf Glow Discharge
Authors: Ichimura Takeshige , Ihara Takurou , Hama Toshio , Ohsawa Michio , Sakai Hiroshi , Uchida Yoshiyuki
Published: November 2005

The a-SiGe:H films produced in the triode system possess better photoconductivity, lower density of dangling bond and very sharp Urbach tail as compared with film produced in the conventional diode system. Such superior properties are attributed to their homogeneous structures, as confirmed by hydrogen evolution experiments and TEM observation.
Metalorganic Molecular Beam Epitaxial Growth of ZnSe Using Diethylzinc and Diethylselenide
Authors: Ando Hideyasu , Taike Akira , Kimura Ryuuhei , Konagai Makoto , Takahashi Kiyoshi
Published: November 2005

ZnSe epitaxial layers have been grown for the first time on (100) GaAs substrates by metalorganic molecular beam epitaxy using diethylzinc and diethylselenide. Diethylselenide is cracked by the cracking furnace. Smooth single-crystalline layers can be grown at substrate temperatures above 200°C. Photoluminescence spectra vary noticeably with the substrate temperature. Above 400°C, the spectra measured at 71 K were dominated by intense blue donor-acceptor pair bands, and broad luminescence bands at longer wavelengths were weak.
Molecular Beam Epitaxy of Controlled Single Domain GaAs on Si (100)
Authors: Kawabe Mitsuo , Ueda Toshio
Published: November 2005

Single domain GaAs layers have been grown on Si (100) surface by molecular beam epitaxy. RHEED observation indicates that antiphase disorder could be suppressed by tilting the orientation of Si (100) surface around <110> axis but were unavoidable on just (100) surface. The off-axis substrates also improve the surface morphology.
A Super Thin Film Transistor in Advanced Poly Si Films
Authors: Ohshima Takefumi , Noguchi Takashi , Hayashi Hisao
Published: November 2005

A super thin film transistor (SFT), the active layer poly Si of which is 150–200 Å thick, is advanced by Si+ implantation and solid phase growth. Poly Si films were amorphized by Si+ implantation, and then regrown by annealing at 600°C in N2 atmosphere for 15 hrs. The maximum grain size increases to 1 µm and electrical properties are advanced. SFT's were fabricated using this technique, and the Si- dose and acceleration energy dependence of field effect mobility µFE were evaluated. µFE of more than 100 cm2/V·s is obtained at 40 keV and above 2×1015/cm2 Si+ dose in 800 Å thick films before oxidation.
Fabrication of SiO2-GeO2 Glass by the Sol-Gel Method
Authors: Shibata Shuichi , Kitagawa Takeshi
Published: November 2005

In the lower GeO2 content region, fabrication of GeO2-doped silica glasses by sol-get method was investigated with emphasis on the influence of GeO2 crystal generation. The generation of GeO2 crystal depends on the ammonia water content in the sol solution. The conversion efficiency of Ge alkoxide is related to the content of GeO2 crystals.
Minority Carrier Lifetime in Laser Recrystallized Polysilicon
Authors: Sakata Isao , Hayashi Yutaka , Ishii Ken-ichi , Takahashi Tetsuo , Yamanaka Mitsuyuki
Published: November 2005

We have measured the minority carrier (electron, in this case) lifetime in the laser recrystallized polysilicon on ceramics substrates by the open circuit voltage decay (OCVD) method and by the modulated photocurrent (MPC) method. We have found from both measurements that the lifetime in the Si film is comparable to or longer than 1 µs. We have discussed briefly the possible reasons for this rather long lifetime for recrystallized material.
Polymeric Product of Carbon Disulfide and Its Electrical Properties
Authors: Tsukamoto Jun , Takahashi Akio
Published: November 2005

The polymeric product of carbon disulfide (CS2) was obtained at normal pressure below room temperature by chemical polymerization with anionic catalyst. This product is very similar to CS2 polymer obtained by conventional method using a high pressure technique (55 kilobars), inferring from the results of IR measurement. The conductivity can be increased to 10-2∼10-3S/cm with ammonia and iodine doping. The structure is discussed from the results of XPS measurement.
Reversible Write-Erase Properties of CuTCNQ Optical Recording Media
Authors: Hoshino Hiroshi , Matsushita Shunsuke , Samura Hideo
Published: November 2005

Homogeneous thin films of CuTCNQ were prepared by vapor-deposition method and were found to be writable and erasable with LD beams. Threshold irradiation time to write spots was 3 to 5 µs with LD power of 16 mW at the wavelength of 810 nm. The readout signal contrast was 27. About fifty write-erase cycles were achieved by applying a ZnS protective layer on the CuTCNQ film.
Photoinduced Effect on Surface Spin Wave Modes in Hydrogen Ion-Implanted YIG Thin Films
Authors: Tsuchiya Toshio , Uematsu Kenichi
Published: November 2005

Photoinduced effect is observed by the decrease ΔH
p of ferromagnetic resonance field of surface spin wave modes in the H+
2 implanted layer of YIG films during light irradiation. Etching depth dependence of the resonance field H
r of surface spin wave modes and ΔH
p is measured. The depth for the maximum of ΔH
p is deeper than that of H
r. With 250°C, 30 minute annealing ΔH
p is remarkably reduced. The decrease ΔH
p in as-implanted films is attributed mainly to generation of Fe2+ ions with hydrogen presence. Relaxation of ΔH
p with annealing is also studied.
Atomic Resolution TEM Images of the Au(001) Reconstructed Surface
Authors: Hasegawa Tsuyoshi , Kobayashi Kunio , Ikarashi Nobuyuki , Takayanagi Kunio , Yagi Katsumichi
Published: November 2005

Au(001) reconstructed surface is directly observed in the profile-imaging mode of the surface observation with use of an ultra-high vacuum high resolution 1 MV electron microscope. Au particles are deposited in-situ in the microscope and clean (001) surfaces are observed along the [110] direction. In the image, six atomic rows in the top Au layer form a corrugation so as to fit five atomic rows in the underlying (001) atomic plane of the fcc lattice. The corrugation is due to the reconstruction along the 5 times superperiod direction of the Au(001)5×28 structure. The height of the corrugation is about 0.03–0.11 nm in agreement with recent scanning tunneling microscope study of the Au(001) surfaces.
Si Etching with a Hot SF6 Beam
Authors: Suzuki Keizo , Ninomiya Ken , Nishimatsu Shigeru , Okada Osami
Published: November 2005

Si surface etching using a hot SF6 (SF*
6) molecular beam has been studied in the interests of studying an effect of vibrational energy on surface reaction and developing a damage-free etching technique. The SF*
6 beam is produced by free expansion of SF6 gas heated in a quartz furnace. It is seen that SF*
6 vibrational energy enhances the Si etch rate. This conclusion is supported by an experimental evidence that Si etch rate under a 915°C substrate temperature increases 3.7 times if the furnace temperature is raised from 100°C to 730°C.
Photo-Ionization of Aluminum Atoms by Vacuum Ultra Violet Light
Authors: Fuyuki Takashi , Dohmae Shin'ichi , Matsunami Hiroyuki
Published: November 2005

Photo-ionization rate of AN atoms by vacuum ultra-violet light has been measured quantitatively for the first time. The ionization rate increased with increasing photon intensity, and the maximum value of 14 ppb was obtained. Simple theoretical analyses of the measured dependences of the ionization rate on the Al flux density and photon intensity revealed that the absorption cross section for ionization was independent of the Al flux density and the photon intensity, and the one-photon ionization process was dominant.
SIMS Study of Compositional Disordering in Si Ion Implanted AlGaAs–GaAs Superlattice
Authors: Kobayashi Junji , Nakajima Masato , Bamba Yasuo , Fukunaga Toshiaki , Matsui Kazunori , Ishida Koji , Nakashima Hisao , Ishida Koichi
Published: November 2005

Compositional disordering in Si ion implanted AlGaAs–GaAs superlattices (SL's) has been studied by SIMS. It is found that Si diffuses fast when the Si concentration exceeds 3×1018 cm-3. The disordering of the SL's always occurs with this fast Si diffusion. It is suggested that the disordering of the SL's is induced by the substitutional exchange of (Si
I
I
I
–Si
V
) pairs with the matrix vacancies. The Si diffusion in the SL layer is not enhanced by the presence of the GaAlAs/GaAs interface.
Subgap Absorption of Boron-Doped and Undoped a-SiC:H Detected by Photothermal Deflection Spectroscopy
Authors: Asano Akihiko , Ichimura Takeshige , Sakai Hiroshi , Uchida Yoshiyuki
Published: November 2005

Subgap absorption of boron-doped and undoped a-SiC:H alloys is studied by photothermal deflection spectroscopy(PDS). In undoped a-SiC:H, the PDS deduced mid-gap states density N
s shows saturation at 2–5% carbon flow ratio (C2H2/SiH4), while Urbach energy monotonously increases with increasing carbon content. Doping with boron to a-SiC:H also increases N
s and Urbach energy, which tendency is similar to that of a-Si:H. There is no evidence of boron compensating the carbon-induced defects in a-SiC:H. The photoconductivity enhancement of a-SiC:H by doping boron must be attributed to the change of occupation in the gap states.
Damage Profile in GaAs, AlAs, AlGaAs, and GaAs/AlGaAs Superlattices Induced by Si+-Ion Implantation
Authors: Matsui Kazunori , Takatani Shin-ichiro , Fukunaga Toshiaki , Narusawa Tadashi , Bamba Yasuo , Nakashima Hisao
Published: November 2005

Rutherford backscattering of 2-MeV He+ with channeling was used to study the damage distribution produced in GaAs, AlAs, Al0.4Ga0.6As, and GaAs/Al
x
Ga1-x
As superlattices by Si+-ion implantation. The results indicate that (1) the amount of damage in Al0.4Ga0.6As is less than that in GaAs, although that in AlAs is almost the same as that in GaAs, and (2) GaAs layers are selectively damaged in superlattice structures independent of Al composition in Al
x
Ga1-x
As.
Hole Transport in Glow-Discharged a-Si:H Films Compensated with Boron
Authors: Shirafuji Junji , Shirakawa Kazuhiro
Published: November 2005

In lightly boron-doped a-Si: H films electrons become highly dispersive in time-of-flight measurement while holes clearly show a non-dispersive transport, in drastic contrast with observations in undoped or lightly phosphorus-doped films. Mechanisms responsible for the drastic change in the electronic transport characteristic between undoped or phosphorus-doped slightly n-type and lightly boron-doped films are briefly discussed.
Velocity-Field Measurement of a Vortex by Dynamic Image Processing
Authors: Miike Hidetoshi , Kurihara Yasushi , Koga Kazutoshi , Hashimoto Hajime
Published: November 2005

A new dynamic image processing technique is applied to the measurement of the velocity of a vortex flow. Velocity-field of the vortex (i.e., the spatial distribution of speed and that of moving direction) is measured and visualized by pixel-based analysis calculating the mutual-correlation functions among temporal brightness changes at each pixel. It is shown that the dependence of the measured local speed V on the distance from the center of the vortex r is approximately V\varpropto(1/r), consistent with the results of pioneers in the field.
Growth of High-Quality ZnSe Layers in Hydrogen Plasma
Authors: Matsumoto Takashi , Yoshida Shigeki , Ishida Tetsuro
Published: November 2005

High-quality ZnSe layers have been grown on (100) GaAs substrates at a temperature as low as 320°C in hydrogen plasma using metallic Zn and Se as source materials. ZnSe layers grow coherently on GaAs substrates up to epitaxial-layer thicknesses of about 0.2 µm. The growth rate is about 1.4µm/h. The photoluminescence spectrum at 4.2K is dominated by a neutral-donor bound exciton emission at 2.7966 eV and a free exeiton emission with lower and upper polariton peaks. The near-bandgap emission dominates the spectrum even at room temperature, deep-center emissions being very weak.
Low Threshold Field of Electro-Optic Effect in Ferroelectric Liquid Crystal with Extremely Large Spontaneous Polarization
Authors: Yoshino Katsumi , Kishio Shin-ichi , Ozaki Masanori , Sakurai Takao , Mikami Naoko , Higuchi Ryo-ichi , Honma Masao
Published: November 2005

Electro-optic effects in newly synthesized ferroelectric liquid crystals (2S,3S)-3-methyl-2-halopentanoic acid 4',4''-alkoxybiphenyl ester have been studied and it is clarified that these materials demonstrate low threshold fields and high response speeds of electro-optic effects corresponding to their large spontaneous polarization.
Phased-Array with the “YY" Shaped Symmetrically Branching Waveguide (SBW)
Authors: Taneya Mototaka , Matsumoto Mitsuhiro , Kawanishi Hidenori , Matsui Sadayoshi , Yano Seiki , Hijikata Toshiki
Published: November 2005

An AlGaAs phased-array laser diode with the SBW structure like the character “YY” is described. In such arrays, single 0° phase mode operation is achieved up to output power about 50 mW. This shows that SBW structure has the ability to select 0° phase mode and to suppress higher order array modes.
Reduced Rate Equation for Atomic Process in High-Z Plasmas
Authors: Itoh Motoshi , Yabe Takashi , Kiyokawa Shuji
Published: November 2005

A new atomic model is proposed which takes advantage of unified characteristics in the level dynamics of excited states. This unified behavior is justified by the collisional-radiative model for medium-Z plasmas and is found to be well approximated by the average ion model. In the new model, the energy functional form of the population probability constructed from the average ion model is used to estimate the level population of ions having different charge from that of the average ion. The model is applied to the X-ray generation in laser-irradiated Au plasmas.
Measurement of Intensity and Polarization of HeI Forbidden Lines for Diagnostics of Electric Field in a Plasma
Authors: Takiyama Ken , Usui Tatehito , Kamiura Yositomo , Fujita Toshiaki , Oda Toshiatsu , Kawasaki Ken
Published: November 2005

Intensity of the HeI 491.1 nm (41P→21P) forbidden line due to the Stark effect, with respect to the HeI 396.5 nm (41P→21S) allowed line, was measured to obtain radial distribution of the electric field in a hollow cathode discharge. The polarization of the lines was also observed to show a capability of detecting the field direction in plasmas. The measured electric field distribution satisfactorily yielded the cathode fall potential, and the polarization was well in agreement with the theoretical prediction. The experiment demonstrated that field strength as low as 250 V/cm could be accurately measured using the present line pair.
Anneal Behavior of Zn Acceptor Implanted In0.53Ga0.47As Layers : a Study of Carrier Distributions
Authors: Rao E. V. K. , Djamei M. , Krauz P.
Published: November 2005

We show here that acceptor Zn or Zn and As dual implants in In0.53Ga0.47As followed by either conventional furnace anneals for short periods (∼1 min at 625°C) or rapid thermal anneals using halogen lamps, permit to achieve high hole concentrations (∼2×1019 holes·cm-3) and abrupt distributions. An explanation to these results is furnished by analysing the measured carrier distributions in terms of defect enhanced Zn diffusion in In0.53Ga0.47As.
A Catalytic Effect of Hexafluorodisilane in Plasma Chemical Vapor Deposition of a-Si:H Films from Monosilane
Authors: Koinuma Hideomi , Manako Takashi , Fueki Kazuo
Published: November 2005

a-Si:H film formation was markedly accelerated by the addition of a small amount of Si2F6 in low power RF glow discharge of SiH4. The observed catalytic effect of Si2F6 is considered to be originated from one of its easily decomposable properties as was expected from a quantum chemical calculation which indicated a low excitation energy and very weak Si–Si bond. The a-Si:H films prepared are highly photosensitive and substantially identical to those prepared in the absence of Si2F6.
Residual Carbon and Oxygen Surface Contamination of Chemically Etched GaAs (001) Substrates
Authors: Saliètes A. , Massies J. , Contour J.P.
Published: November 2005

Several different cleaning procedures for GaAs (001) substrates are compared using X-ray photoelectron spectroscopy. This work emphasizes the effect of the last etching step: HCl-, HF-ethanol (10%), bromine-methanol (1%), performed on a spinner (3000 rpm) operated in a nitrogen dry box, and running deionized water (RDIW). These four etchants lead to deoxidized surfaces, although RDIW leaves a fractional coverage of sligthly bounded oxygen species (≃0.15 monolayer). The residual carbon contamination is around 0.2 monolayer whatever the etchant used and is removable by flash heating at 400°C under ultrahigh vacuum. RDIW, HCl- and HF-ethanol do not produce any significant etching of the GaAs matrix whereas bromine-methanol (1%) removes ≃0.2 µm per cm3 of solution.
Photoluminescence at 0.5 µm Wavelength in Fluoride Optical Fibers
Authors: Sakaguchi Shigeki , Kanamori Terutoshi , Terunuma Yukio , Ohishi Yasutake , Takahashi Shiro
Published: November 2005

Photoluminescence was found at 0.5 µm in Zr-based fluoride optical fibers. The 0.5 µm luminescence is attributed to Zr ions in a reduced state which is formed during the melting process in glass synthesis. By introducing O2 into the glass melting atmosphere, concentration of the reduced Zr can successfully be decreased. It is also found that the reduced Zr causes a considerable increase in the absorption loss.
A New Interferometric Displacement-Detection Method for Mask-to-Wafer Alignment Using Symmetrically-Arranged Three Gratings
Authors: Itoh Junji , Kanayama Toshihiko
Published: November 2005

A new interferometric detection method of lateral displacement between the mask and the wafer using three gratings was developed. Experimental results show that the present method with 0.86 µm-period gratings has a detection sensitivity better than 0.005 µm independently of mask-wafer gap variations from 79 µm to 93 µm. This method is quite suitable for the precise mask-to-wafer alignment required in such proximity exposure systems as used in the X-ray lithography. The principle and experimental results are described.
Time-of-Flight Separation of Secondary Electrons Due to Metastable He and HeI Photon Beams Produced by Pulsed Hot-Cathode Discharge
Authors: Nishigaki Satoshi , Sugihara Masato , Ohara Mutsuo , Fukui Shinji , Matsuo Kenji , Noda Tamotsu
Published: November 2005

Velocity distribution of He metastable atoms produced by hot-cathode discharge has been measured by a time-of-flight technique. It is comparable to Maxwell's velocity distribution characterized by the temperature around 1400 K. Secondary electrons from a target Si(111) surface ejected late from discharge pulses presented metastable-atom deexcitation spectra, whereas electrons ejected in coincidence with discharge pulses showed photoelectron spectra. The possible mechanism of metastable-atom deexcitation at the surface is described.
InGaAsP/InP Hetero Junction Bipolar Transistor with High Current Gain
Authors: Fukano Hideki , Itaya Yoshio , Motosugi George
Published: November 2005

N-InP emitter, p-InGaAsP base and n-InGaAsP collector hetero junction bipolar transistors (HBT's) were fabricated. It has been shown that a maximum current gain of more than 10,000 is obtained with a base carrier concentration of 5×1017 cm-3 and a 0.15 µm base width. The current gain decreases notably as the base carrier concentration increases. This behavior is explained by the decrease in emitter efficiency caused by the increase in recombination-generation current in the emitter-base depletion region.
MBE Growth of High-Quality GaAs Using Triethylgallium as a Gallium Source
Authors: Kondo Kazuhiro , Ishikawa Hideaki , Sasa Shigehiko , Sugiyama Yoshihiro , Hiyamizu Satoshi
Published: November 2005

High-quality GaAs was grown by gas source MBE using TEGa (triethylgallium) and metal arsenic. An unintentionally doped GaAs layer (6.5 µm thick) exhibited p-type conduction with the carrier concentration as low as 8×1014 cm-3 (room temperature) and highest hole mobility of 5930 cm2/Vs (39 K). The carrier concentration in GaAs obtained is the lowest ever reported for GaAs grown by gas source MBE or MO–MBE.
Generation Rule of the Slip Dislocation in LEC GaAs Crystal
Authors: Kitano Tomohisa , Ishikawa Tetsuya , Ono Haruhiko , Matsui Junji
Published: November 2005

In a (001) low dislocation density wafer, an eight-fold circular strain field was observed near the periphery between <110> and <100> radii. The observed result was explained from the viewpoint of ease of slip dislocation generation by calculation of Schmid factor magnitude distribution under the condition that major thermal stress was applied to tangential direction at the round ingot surface. While, in a (001) high dislocation density wafer, a four-fold strain field was observed around the <100> radii. The result was explained by intersection of slip dislocation generated from eight positions at the periphery between <110> and <100> radii as well.
Guiding Principle in the Preparation of High-Photosensitive Hydrogenated Amorphous Si–Ge Alloys from Glow-Discharge Plasma
Authors: Matsuda Akihisa , Koyama Masato , Ikuchi Nozomu , Imanishi Yuichiro , Tanaka Kazunobu
Published: November 2005

A guiding principle has been proposed for the preparation of high-photosensitive hydrogenated amorphous Si–Ge alloys (a-SiGe:H) via the plasma chemical-vapor-deposition technique. According to this principle, plasma parameters in a diode-type reactor were systematically controlled, resulting in high-quality a-SiGe:H films in the optical-gap range between 1.4 and 1.8 eV. Photoconductivity-to-dark-conductivity ratio of the best-designed a-SiGe:H with 1.45 eV optical gap was found to reach 104.
The Effect of Lattice Misfit on Lattice Parameters and Photoluminescence Properties of Atomic Layer Epitaxy Grown ZnSe on (100)GaAs Substrates
Authors: Yao Takafumi
Published: November 2005

The effect of lattice misfit on photoluminescence properties and lattice parameters of ZnSe thin films grown by atomic layer epitaxy on (100)GaAs substrates has been investigated. It is observed that ZnSe layers thinner than 0.17 µn suffer complete tetragonal distortion, while films thickner than 0.17 µm show relief from the misfit strain. The residual stress in the epilayers amounts to 1.84×109 dyn/cm2 assuming complete tetragonal distortion. The thin films exhibit both free exciton emission and deep emission, while the thick films exhibit dominant bound exciton emission at donors and weakdeep emission.
Room-Temperature Characterization of Midgap Level (EL2) in GaAs Diodes without Metallization Processes
Authors: Okumura Tsugunori , Hoshino Minoru
Published: November 2005

A midgap level (EL2) in GaAs has been characterized at room temperature by the TDS-ICTS technique in samples without metallization processes. Liquid metals (Hg and In–Ga alloy) and electrolyte (0.1N–HCl) have been used for a rectifying contact to bulk GaAs crystals. For epitaxial p+/n diodes, deep levels have been measured in a cleaved dice just with a liquid metal on both surfaces. The spectrum for EL2 in these samples has been the same as that in the usual Schottky diodes with an evaporated metal.
Near-Band-Edge Photoluminescenee of High-Purity GaxIn1-xP Grown by Chloride Vapor-Phase Epitaxy
Authors: Kodama Kunihiko , Hoshino Masataka , Kitahara Kuninori , Ozeki Masashi
Published: November 2005

A bound-exciton (BE) emission was studied for high-purity Ga
x
In1-x
P layers grown at various temperatures by chloride VPE. In contrast to the results for the metalorganic-VPE layers, its photon energy did not depend on growth temperature in the range examined (560–760°C). Furthermore, two faint bands were iuavestigated which were observed at photon energies lower than that of BE. They were interpreted from their dependences on temperature and excitation intensity as being due to a donor-acceptor pair emission superimposed by a phonon replica of BE, and to a phonon replica of BE with emission of two phonons.
Threshold-Voltage Stability of P-Channel AIGaAs/GaAs MIS-like Heterostructure FETs
Authors: Hirano Makoto , Kondo Naoto
Published: November 2005

Threshold-voltages V
th of p-channel AlGaAs/GaAs MIS-like heterostructure FET
s
(p-MIS HFETs) were found to be constant -0.5(±0.05) V at 77 K, independent of the AlGaAs layer thickness (8 to 30 nm), when the impurity concentration of the buffer layer was a smaller value than 5×1015 cm-3. The standard deviation of V
th was measured to be 24 mV at 77 K with the 3 µm gate FET devices in a quartering 2-inch-diameter wafer. Turn-on voltages of p-channel diodes were measured with 1 MHz to be in good agreement with the threshold voltage of the FET devices.
Barrier Height in Indirect Bandgap AlGaAs/GaAs Hetero-Junction Determined with n-Semiconductor/Insulator/Semiconductor Diodes
Authors: Maezawa Koichi , Mizutani Takashi , Yanagawa Fumihiko
Published: November 2005

Electron transport through the GaAs/Al
x
Ga1-x
As/GaAs n-semiconductor/insulator/semiconductor diodes (x>0.45) is studied to clarify the valley which determines current conduction. The potential barrier for thermionic emission current was shown to be determined by the X valley of AlGaAs in the indirect bandgap region. It was also directly shown that conduction band discontinuity decreases when increasing the Al mole fraction of AlGaAs layer beyond the band cross over point. The most suitable Al mole fraction of undoped AlGaAs used as the gate insulator of n-channel GaAs MISFETs is concluded to be about 0.45.
Formation of Polycrystalline SiC in ECR Plasma
Authors: Chayahara Akiyoshi , Masuda Atsuhiko , Imura Takeshi , Osaka Yukio
Published: November 2005

Crystalline films of SiC were formed using CVD method in electron cyclotron resonance plasma, generated by microwave (2.45 GHz) discharge in mixed gas of silane, methane, and hydrogen under the magnetic field. Depositionrate was ∼4 A/s and film composition C/Si=1.1. The largest grain size is at least 800 A which is estimated from X-ray diffraction measurements.
Emission Stability of Au–Si–Be LM Ion Source in Various Gas Environments
Authors: Arimoto Hiroshi , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

Emission stability of a Au–Si–Be liquid metal (LM) ion source under various gas environments has been investigated. It was found that the ion emission stability was influenced by oxygen or water vapor which seemed to result in oxidation of the alloy surface. Water vapor is particularly active with Be atoms in the alloy.
We have confirmed that stationary, stable ion beams (Si, Be) with a constant ion current and a beam diameter can be obtained by operating the ion source under a high vacuum enclosure of 2×10-7 Torr in a 100 kV focused ion beam implanter (FIBI).
Far-Infrared Magneto-Absorption of Bound Excitons in Beryllium Doped Germanium
Authors: Nakata Hiroyasu , Otsuka Eizo , Haller Eugene E.
Published: November 2005

A bound exciton is observed in far-infrared magnetoabsorption measurements of photo-excited beryllium doped germanium below 4.2 K. The absorption corresponds to the 1s to 2p± like transition of the electron in the bound exciton. Fifteen branches of peaks converge to about 3.4 meV at zero magnetic field. The 1s like ground state splits into more than two levels at zero magnetic field. The 2p± like excited state with an ionization energy of 1.7 meV is well described by the effective mass approximation.
Selective Coordination Epitaxial Growth of Quasi-One-Dimensional Transition Metal Coordination Compounds
Authors: Tanino Hiroshi , Takahashi Kazuhiro , Yao Takafumi
Published: November 2005

Selective coordination epitaxial growth (SCE) of transition metal coordination compounds, a new growth technique of new materials in the field of electronics, is proposed and demonstrated. A heterostructure of halogen-bridged mixed-valence metal complexes is epitaxially grown successfully for the first time. This method is a powerful technique, which produces various kinds of superlattice of transition metal coordination compounds.
Changes of Structure and Magnetization of Amorphous Rare Earth-Transition Metal Films by Annealing
Authors: Saito Nobuo , Togami Yuji , Morishita Tadataka , Sato Ryuji
Published: November 2005

Magnetization (M) and X-ray diffraction patterns of amorphous Gd–Tb–Fe films were measured. The film annealed at 330°C for 3 hours under a pressure of low vacuum (1×10-3 Torr∼1×10-2Torr) showed X-ray diffraction peaks corresponding to bcc Fe and oxides of rare earth metals, and its M increased. We concluded that these results and the irreversible increase of M at temperatures higher than 200°C are caused by clustering of Fe due to immiscibility of Fe with selectively oxidized rare earth metals. To determine the exact crystallization temperature of amorphous RE-TM films, oxidation of the films must be carefully avoided.
A Shaped Projectile for Hypervelocity Impact as a Driver of Nuclear Fusion
Authors: Ikuta Kazunari
Published: November 2005

Design criteria are given of a shaped projectile for implosion by hypervelocity impact using black body radiation. The cavity inside the projectile should be covered by a sufficiently thin film made of high atomic weight material.
Diffusion from SiO2:Zn Spin-on Films into n-In0.53Ga0.47As
Authors: Albrecht H. , Lauterbach Ch.
Published: November 2005

Zn-diffusion from SiO2:Zn spin-on films into n-InGaAs for the preparation of p-n junctions has been investigated. The measured p-n junction depths versus diffusion time are in accordance with a diffusion model which considers the spin-on film as an exhaustable diffusion Zn-source. Depending upon the composition of the SiO2:Zn-films diffusion depths proportional to the square-root of diffusion time t or depths nearly independent of t were observed.
Optimization of the Growth Conditions of Heteroepitaxial GaAs Films on CaF2/Si Structures
Authors: Lee Hee Chul , Asano Tanemasa , Ishiwara Hiroshi , Furukawa Seijiro
Published: November 2005

Dependences of the crystallinity and surface morphology of GaAs films grown on CaF2/Si structures on such growth parameters as substrate temperature, growth rate and substrate orientation have been investigated. It has been found that GaAs films having both good crystalline quality and smooth surface can be grown on the (111) substrates by decreasing the growth rate and the substrate temperature, while the crystalline quality of the films on the (100) substrates is virtually independent of the growth rate.
Freezing Point Depression within a Shear Field and the Effect of a Shear Field on Crystallization of Bi-Pb-Sn-Cd Alloy
Authors: Mishina Hiroshi , Sasada Tadashi , Watanabe Kunio
Published: November 2005

A melting (or freezing) temperature, in general, is considered to be dependent only on pressure. However, in a recent paper a new idea was proposed, i.e. the temperature of a phase transition between a liquid and a solid is depressed when a shear field is applied to the materials. In this investigation an experimental study was made with a Bi-Pb-Sn-Cd alloy (Wood's metal) to investigate the depression of freezing temperature within a shear field for a shear rate from 0 to 900 s-1 and the effect of the shear field on crystallization.
Mechanism of Light-Impurity Release in a Tokamak
Authors: Maeno Masaki , Yamamoto Shin , Hirayama Toshio , Ogawa Hiroaki , Ohtsuka Hidewo , Matsuda Toshiaki
Published: November 2005

The dependence of spectral line-intensities on both the electron temperature and the partial pressure of gaseous contaminants in the scrape-off layer has experimentally been studied on the JFT-2M tokamak. The intensities of light-impurities increase with the electron temperature. On the other hand, the intensities are independent on the pressure of the contaminants such as CH4, CO, CO2 and H2O. The relation between the line-intensity and the impurity influx is simulated by using a one-dimensional impurity transport model. The cause of the light-impurity release relevant to physical and chemical sputterings is discussed.
Output Power Change Associated with Longitudinal Mode Jumping in Semiconductor Injection Lasers
Authors: Ogasawara Nagaatsu , Ito Ryoichi
Published: November 2005

Output power change associated with longitudinal mode jumping in an AlGaAs injection laser has been examined. It has been found that the power level for a shorter wavelength mode is higher than that for a longer wavelength mode both at hysteretic mode-jumping and at random mode-switching. The results have been interpreted in terms of asymmetric mode coupling in laser diodes.
Direct Comparison of Quantized Hall Resistance between Si-MOSFET and GaAs/AlGaAs Heterostructure Devices on the Same Sample Holder
Authors: Shida Katsunori , Wada Toshimi , Nishinaka Hidefumi , Igarashi Takashi
Published: November 2005

A direct comparison of quantized Hall resistance between a Si-MOS and a GaAs device on the same sample holder has been made for the first time. The vertical direction of the GaAs device surface is inclined about 60° in the direction of the supplying magnetic field, making the magnetic field of the GaAs device half that of the Si-MOS on the same sample holder. The sample-independences of quantum Hall effect were experimentally verified with an uncertainty of 3×10-7
Electroreflectance Spectra and Field-Induced Variation in Refractive Index of a GaAs/AlAs Quantum Well Structure at Room Temperature
Authors: Nagai Hideo , Kan Yasuo , Yamanishi Masamichi , Suemune Ikuo
Published: November 2005

Observed electroreflectance spectra for a GaAs/AlAs quantum well structure show very clear exciton-induced features at room temperature. A maximum rate for the field-induced modulation of refractive index, Δn/n/E in each quantum well is deduced to be 4%/105 V/cm at a photon energy close to the excitonic gap. Such a large variation in the refractiveindex is attributed to excitonic transitions.
Conduction Band Edge Discontinuity of In0.52Ga0.48As/In0.52(Ga1-xAlx)0.48As(0≦x≦1) Heterostructures
Authors: Sugiyama Yoshihiro , Inata Tsuguo , Fujii Toshio , Nakata Yoshiaki , Muto Shunichi , Hiyamizu Satoshi
Published: November 2005

In0.52Ga0.48As/In0.52(Ga1-x
Al
x
)0.48As/In0.52Ga0.48As potential barrier structures (x=0.25, 0.5, 0.75, 1), lattice-matched to InP, were grown by MBE using a pulsed molecular beam method. The conduction band edge discontinuity, ΔE
c(x) between In0.52Ga0.48As and In0.52(Ga1-x
Al
x
)0.48As, was obtained for the first time by measuring the current-voltage characteristics through the barrier structure as a function of temperature in the range of 77–300 K. It was confirmed that the conduction band edge discontinuity varies linearly with Al composition, x, (ΔE
c(x)=0.53x(eV) for 0≦x≦1) and is proportional to the band gap difference, ΔE
g(x), (ΔE
c(x)=0.72ΔE
g(x)(eV) for 0≦x≦1).
Implantation Energy Dependence of Composilional Disordering in Si Implanted GaAs/AlGaAs Superlattices Studied by Secondary Jon Mass Speetrometry
Authors: Matsui Kazunori , Kobayashi Junji , Fukunaga Toshiaki , Ishida Koichi , Nakashima Hisao
Published: November 2005

Compositional disordering in Si implanted GaAs/AlGaAs superlattices has been studied for various implantation energies by secondary ion mass spectrometry. It is found that at higher energy implantation the disordering is suppressed in the surface region and that the disordering in the deeper region becomes incomplete with the implantation energy. These results are well explained by the formation of damage in the surface region and the reduction of Si concentration, respectively.
Light-Induced Effects and Their Annealing Behavior in a-Si:H
Authors: Kumeda Minoru , Yokomichi Haruo , Morimoto Akiharu , Shimizu Tatsuo
Published: November 2005

It is found from ESR measurements in a-Si:H films that dangling bonds created by short-time illumination can be removed by short-time annealing and that photo-created dangling bonds removed by short-time annealing can be recovered by short-time illumination. Combining these results with temperature dependence of illumination effects for two kinds of films prepared at 100°C and 250°C, a mechanism of the photo-creation of dangling bonds is proposed. The illumination effect on photoconductivity and photoluminescence is also compared with that on ESR.
TEM Observation of Segregated Microstructure in Sputtered Co–Cr Film
Authors: Maeda Yasushi , Asahi Masayoshi , Seki Masahiro
Published: November 2005

TEM observation of the segregated microstructure in sputtered Co–Cr films was conducted. The specific segregated microstructure was observed in the film composition range of 15.3–24.3 at%Cr–Co. The results present a new model for the origin of the segregation where two-phase separation into magnetic and non-magnetic phases occurs in a single hcp phase. The ferromagnetic Co-rich regions in a crystallite are supposed to be embedded in nonmagnetic Cr-rich matrix, with a wall-like figure perpendicular to the substrate plane.
Subharmonic Gap Structure Observed in a Series Array of Thin-Film Josephson Junctions
Authors: Matsui Toshiaki , Ohta Hiroshi , Hayashi Risao
Published: November 2005

The subharmonic gap structure was observed as a striking conductance depression effect in a series array of eleven Josephson junctions. Each element is a type of short superconducting weak-link comprising microshorts in an oxide layer sandwiched between two niobium film electrodes. The experimental observation implied that the ac Josephson effect significantly raised the strong structure at the voltage: V=N2Δ/n
e, where N is a cascade number (N=11), and the integer n means the n-th subharmonic gap structure.
Back-Gated Field Effect in a Double Two-Dimensional Electron Gas Structure
Authors: Sasa Shigehiko , Muto Shunichi , Hiyamizu Satoshi
Published: November 2005

Selective ohmic-contacts were made to double two-dimensional electron gas (2DEG) layers spatially separated by 1000 Å in a GaAs–AlGaAs quantum well heterostructure. A HEMT-type device was fabricated by utilizing a surfaceside 2DEG layer as an active channel and substrate-side 2DEG as a backside gate conductor. The transconductance increased by 50% with an applied back-gate bias as low as 1 V. This bias is about three orders of magnitude lower than any previously reported back-gated HEMT structures. Hot-electron transfer between the two 2DEG layers, induced by the applied electric field, was also observed.
A Proposal of a New Technique of Atomic Beam-Doppler Speetroscopy for Electric Field Measurement in Plasma
Authors: Mimura Mikio , Sakai Yoshiyuki , Katsumata Itsuo
Published: November 2005

A new diagnostic technique for the measurement of the electric field in a magnetically confined plasma is proposed. A neutral atomic beam is injected into the plasma as the probe. The local electric field in the plasma can be determined from the optical Doppler shift, which is related to the so-called E×B drift, of a spectral line emitted by those ions which are ionized from the probing beam. The photon number and the spectrum profile is evaluated using a simple model. Two important factors for the present proposal, the necessary intensity of the beam and the resolution of the spectroscopie system are discussed.
Fabrication of Index-Guided AlGaAs Multiquantum Well Lasers with Buried Optical Guide by Si-Induced Disordering
Authors: Ishida Koji , Matsui Kazunori , Fukunaga Toshiaki , Takamori Takeshi , Nakashima Hisao
Published: November 2005

Transverse mode controlled AlGaAs–GaAs multiquantum well(MQW) lasers with buried MQW optical guide (MQWBOG) have been developed using compositional disordering induced by Si ion implantation and subsequent annealing. It is confirmed that the MQW-BOG lasers fabricated by these simple and completely planar processes operate in a fundamental transverse and single longitudinal mode.
Compression of a Cylindrical Thin Target by Intense Ion Beams Generated in the “Point Pinch Diode”
Authors: Tazima Teruhiko , Sato Morihiko , Yonezu Hiroaki
Published: November 2005

A new concentric elliptic diode (called the “Point Pinch Diode”) is proposed in which relativistic electron beams tightly pinch at a point on the outer anode center. The pinched beam forms a dense plasma and an intense ion beam from the plasma is generated. This ton beam flows to a cylindrical thin target on the cathode and compresses it. Observed ion beam fluxes are 3 kA/cm2∼15 kA/cm2 when respective voltage, pulse duration time, and a gap length are 250∼380 kV, 40∼70 ns, 0.5∼3 mm. Major components of the ion beam are hydrogen, oxygen, and carbon, the origin of which is gas absorbed on the anode.
Nb/Al-oxide/Nb Tunnel Junctions for Josephson Integrated Circuits
Authors: Nakagawa Hiroshi , Nakaya Kenji , Kurosawa Itaru , Takada Susumu , Hayakawa Hisao
Published: November 2005

A new fabrication process of small Nb/Al-oxide/Nb tunnel junctions for integrated circuits is presented. Prior to making tunnel junctions of Nb/Al-oxide/Nb sandwich structure with a full wafer size, an Nb electrode layer was prepared on the wafer, whose patterns were duplicated from each junction base electrode pattern. This additional underlayer of Nb plays an important role in improving I–V characteristics, especially in the small size Nb/Al-oxide/Nb junctions. A reactive ion etching process was employed to define each junction size precisely. Using the present process, Vm=40 mV and Rsg/Rnn=26 with a critical current density of 1000A/cm2 have been achieved in an one-hundred 2.5 µm square junction array.
A New Method for Preparing Fluoride Glass Preforms
Authors: Nakai Tetsuya , Mimura Yoshinori , Shinbori Osamu , Tokiwa Hideharu
Published: November 2005

A new method for preparing fluoride glass preforms has been developed. This technique utilizing a double crucible permits the conduct of all fabrication processes under an NF3 atmosphere.
Surface Extended Energy Loss Fine Structure (EELFS) above Cr L2,3 Edge
Authors: Ishida Tadashi
Published: November 2005

The oscillations of extended energy loss fine structure (EELFS) have been clearly observed above the L2,3 edge of polycrystalline Cr in the reflection mode with a conventional CMA electron analyser. The spectrum and the result of its Fourier analysis have been very similar to the previous results of extended X-ray-edge energy loss fine structure analysis. The observed Cr spacing 2.51 Å by this EELFS analysis is very close to the Cr bulk spacing (2.50 Å).