bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Nonradiative Processes in Benzene Vapor by Photoacoustic Spectroscopy
Authors: Nakamura Hiromichi , Hiura Yuko , Tsubouchi Kazuo , Mikoshiba Nobuo
Published: November 2005

A photoacoustic (PA) and an absorption spectra of benzene vapor have been measured in the wavelength region from 280 to 220 nm. We determined nonradiative yields at the absorption peaks. We found that the relaxation process of benzene vapor at the wavelengths shorter than 242 nm, whose process has been called the third channel, is a nonradiative relaxation process with temperature rise of the benzene vapor. We also observed a drastic decrease of the nonradiative yields at wavelengths shorter than 233 nm, which seems to suggest an increase of quantum yield for photochemical isomerization.
Photo-Induced ESR in Amorphous Si1-xNx:H Films
Authors: Kumeda Minoru , Yokomichi Haruo , Shimizu Tatsuo
Published: November 2005

A large increase in the spin density for ESR signals originating from Si dangling bonds is observed by illumination at liquid nitrogen temperature for a-Si1-x
N
x
:H films prepared by magnetron-sputtering and glow-discharge-decomposition. The photo-induced ESR can be explained as arising from the following three types of centers; (1) negative U centers which have unpaired spins metastable only under illumination, (2) positive U centers which are converted from negative U centers by illumination and (3) dangling bonds created by a bond-breaking by the intense illumination.
Helically Assisted Low-q Tokamak with l=2 Helical Winding
Authors: Hamaguchi Satoshi , Yamada Hiroshi , Yoshida Zensho , Kamada Yutaka , Hattori Ken-ichi , Inoue Nobuyuki , Uchida Taijiro
Published: November 2005

An l=2, m=5 short-pitch helical field has been applied to low safety factor (q(a)∼2) discharges in the TORIUT-5 tokamak. The externally applied helical field increases the safety factor effectively to avoid the current driven instabilities. An l=2 helical winding has the advantage, in comparison with an l≧3 system, of controlling the pitch near the magnetic axis and reducing the internal instability. The experimental results show a good agreement with theoretical estimates.
Far-Infrared Magneto-Absorption of Bound Excitons in Zinc Doped Germanium
Authors: Nakata Hiroyasu , Otsuka Eizo
Published: November 2005

Bound exciton in zinc doped germanium is observed in far-infrared magneto-absorption measurement. The spectrum is well explained by a donor-like model. The absorption is due to excitation of an electron from “1s” ground state to “2p±” excited state. It thus gives information on the odd parity states of the complex that is inaccessible in a photoluminescence experiment. The lifetime of a bound exciton is 0.8 µs at 4.2 K in the magnetic field of 2 T.
Extremely Low Resistance Ohmic Contacts to n-GaAs for AlGaAs/GaAs Heterojunction Bipolar Transistors
Authors: Ito Hiroshi , Ishibashi Tadao , Sugeta Takayuki
Published: November 2005

New AuGe/Ni/Ti/Au multi-layer structure ohmic contact to n-GaAs is reported which is suitable to fabricate fine emitter and collector patterns of AlGaAs/GaAs heterojunction bipolar transistors. According to an Auger electron spectroscopy investigation, a new alloying mechanism takes place in reducing contact resistivity. A contact resistivity of 3×10-7Ω·cm2 for 3×1018cm-3 doped n-GaAs was achieved through optimum alloying at 370°C.
Mono- and Bi-Layer Superlattices of GaAs and AlAs
Authors: Sano Naokatsu , Kato Hiromu , Nakayama Masaaki , Chika Shigeaki , Terauchi Hikaru
Published: November 2005

The synthesis and X-ray diffraction study of superlattices grown by exactly alternate depositions of monolayers of GaAs and AlAs are reported. The mono- and bi-layer superlattices were synthesized by molecular beam epitaxy utilizing the intensity oscillations in the specularly reflected beam in the RHEED pattern during growth. The X-ray diffraction profile implies that the synthesized monolayer crystal has a simple cubic symmetry. The satellite diffractions for the synthesized bilayer superlattice were clearly detected at L=0.5, 1.0, 1.5, 2.5, 3.0 and 3.5.
Ion-Trapping Effect in UVSOR Storage Ring
Authors: Kasuga Toshio , Yonehara Hiroto , Kinoshita Toshio , Hasumoto Masami
Published: November 2005

UVSOR is an electron-stage ring dedicated to vacuum ultraviolet synchrotron radiation research. The first beam was stored in the ring in November 1983, and from that time on, efforts have been devoted to improving the performance of the ring. Some inconvenient phenomena have been found during the accelerator studies. One of the most serious problems is the growth of the vertical size of the electron beam. This phenomenon is explained by the ion-trapping effect, in which the ions trapped in the electron beam change the operating point of the storage ring and enhance the coupling between horizontal and vertical oscillations, resulting in a considerable increase in the vertical beam size. This ion trapping was successfully cured by the RF knockout method, which excited the betatron oscillation.
Effect of Ion-Irradiation on Silicide Formation in Metal-Silicon System with Interfacial Silicon Dioxide Layer
Authors: Horino Yuji , Matsunami Noriaki , Itoh Noriaki
Published: November 2005

The thermal and ion-induced formation of Pd2Si in a Pd-Si system with an interfacial SiO2 layer has been investigated. It is found that the blocking of the thermal silicide formation by the SiO2 layer is partially removed by pre-irradiation with ions, inducing a quadratic, laterally non-uniform thermal growth of the silicide. The growth of the silicide layer under irradiation with light ions is found to be a linear function of the ion fluence. Light ion irradiaticn is shown to induce laterally non-uniform silicide formation, whereas uniform silicide is formed by heavy ions. The result is analyzed using a model in which the blocking of the reaction by SiO2 is partially destroyed by ion-irradiation. A criterion for uniform silicide growth from a contaminated metal-silicon system is presented.
Effect of Arsenic Source on Electron Trap Concentrations in MBE-Grown Al0.2Ga0.8As
Authors: Naritsuka Shigeya , Yamanaka Kenichi , Mannoh Masaya , Mihara Minoru , Ishii Makoto
Published: November 2005

Electron traps in n-Al0.2Ga0.8As layers grown by molecular beam epitaxy (MBE) have been studied by deep level transient spectroscopy. When compared among the layers grown sequentially, the concentrations of the two dominant trap levels, ME5 (activation energy 0.63 eV) and ME6 (0.71 eV), are found to decrease markedly with the growth run number. The trap concentrations also depend sensitively on the choice of arsenic source material. These results show that the traps are closely associated with volatile impurities in arsenic materials.
Effect of Contamination on Arc Initiation on a Metal Surface Exposed to Plasma
Authors: Kudo Kouichi
Published: November 2005

The initiation of arcs on a metal surface stained by contamination and exposed to a plasma has been studied experimentally and with the use of a calculation model. It is assumed in the calculation model that a negative voltage is applied to a metal specimen with respect to the plasma potential, arcs are initiated when the electric field strength due to the voltage drop produced in the contaminant layer is large enough to induce dielectric breakdown in the layer, and that the conditions for arc initiation in the gap between the plasma and the metal surface are fulfilled by the burst of vapor produced when dielectric breakdown occurs. The variation of the arc initiation voltage with the plasma density and the variation of the time lag before arc initiation with the applied voltage were obtained experimentally. These experimental results can be qualitatively explained by the results obtained from the calculation model.
Numerical Solution of the Free Surface Drainage Problem of Two Immiscible Fluids by the Boundary-Element Method
Authors: Natori Makoto , Kawarada Hideo
Published: November 2005

A numerical method is presented for solving the unsteady porous flow problem of two immiscible fluids with free surfaces. The velocity potential of each fluid is expressed as the solution of the Laplace equation, which is solved by the boundary-element method. The free surface equation is solved by a Crank-Nicolson type procedure.
Photochromic Evaporated Films of Spiropyrans with Long Alkyl Chains
Authors: Hayashida Shoichi , Sato Hirotsugu , Sugawara Shungo
Published: November 2005

Organic thin films consisting of spiropyrans with long alkyl chains were prepared by evaporation. These films crystallized immediately or gradually in an ambient atmosphere. It has been demonstrated that introduction of long alkyl chains is an effective way to obtain transparent and smooth films by evaporation and that reversible photo-isomerization, a kind of on-off switching, is performed in the films.
New Donor Formation in n-Type Czochralski-Grown Silicon
Authors: Fukuoka Noboru
Published: November 2005

The effects of preannealing in the temperature range from 350°C to 550°C on new donor formation were studied in n-type Czochralski-grown silicon, and it was found that the new donor formation rate is controlled by the density of electrically inactive embryos of new donors. The energy of formation of new donors was found to be 1.7 eV.
The effect of new donors on the thermal donor formation was studied through 650°C annealing and subsequent 450°C annealing. The thermal donor formation is suppressed in the sample containing new donors. The results indicate that carbon atoms have a complex effect on the formation of oxygen donors.
AC-Thin Film ZnS:Mn Electroluminescent Device Prepared by Metal Organic Chemical Vapor Deposition
Authors: Hirabayashi Katsuhiko , Kogure Osamu
Published: November 2005

AC-thin film ZnS:Mn electroluminescent devices are fabricated by the Metal Organic Chemical Vapor Deposition, using dimetylzinc and H2S as source materials. The crystal structure of the MOCVD-prepared ZnS film on glass is (111)-oriented cubic polycrystalline. The electroluminescent center Mn is added into MOCVD-prepared ZnS film through thermal diffusion. The brightness and efficiency of the MOCVD-prepared EL devices are higher than those of the EB-evaporation prepared EL devices having the same structure. The MOCVD-prepared EL devices exhibit few dark spots, and therefore exhibit high stable operation and high breakdown voltage.
Characterization and Surface Cleaning Technique for MOCVD Growth-Interrupted GaAs Films
Authors: Sugiura Hideo , Asai Hiromitsu
Published: November 2005

This paper presents a study of the electrical properties and impuritiy profiles for MOCVD GaAs films fabricated by a sequence consisting of growth interruption, exposure of the surface to air, and resumption of growth. The growth-interrupted interface is depleted of electrons, and carbon, oxygen, and silicon impurities accumulate. The cause of the carrier depletion is found to be carbon acceptors which compensate donors. Wet chemical etching of the air-exposed surface (about 300 Å) is very effective in removing the surface contaminants, and this then eliminates the carrier depletion.
Experimental Raman Cross-Section of Hydrogen and Deuterium Molecules for Absolute Density Calibration of Thomson Scattering Device
Authors: Yamauchi Toshihiko , Yanagisawa Ichiro
Published: November 2005

The Raman scattered light is polarized only 14% by linearly-polarized ruby laser light incident in D2.
The total Raman cross-sections of H2 and D2 for the ruby-laser wavelength of 6943 Å were estimated from an experiment. The Raman cross-section σH2
(J) of the J=2 →0 pure rotational transition for H2 was found to be 2.5·10-30 cm2, while σD2
(J) of the J=3 →1 pure rotational transition for D2 was 2.3·10-30 cm2.
Low-Temperature Formation of β-Type Silicon Carbide by Ion-Beam Mixing
Authors: Kimura Tadamasa , Tatebe Yuki , Kawamura Akira , Yugo Shigemi , Adachi Yoshio
Published: November 2005

This paper reports on the ion mixing of a carbon-silicon system induced by the Ar-ion bombardment of carbon layers deposited by an arc-discharge on single-crystalline silicon substrates. A study using infrared absorption spectroscopy has shown that a disordered carbon-silicon mixture can be obtained immediately after bombardment and that subsequent annealing causes the formation of a crystalline β-type silicon carbide phase at about 800°C. The formation temperature is lower by about 100°C than that for carbon-silicon mixed layers formed by the direct implantation of carbon ions into silicon substrates. Argon-ion bombardment, itself, is found to play an important role in a reduction of the formation temperature.
Possibility of Ion Beam Pulse Compression by X-Ray Conversion
Authors: Yabe Takashi
Published: November 2005

A previously proposed scheme for ion beam pulse compression is reexamined from a different viewpoint. It is shown that the criticisms made by Unterseer and Meyer-ter-Vehn are not reasonable in a real target configuration. In addition, the spherically converging effect is shown to offer further advantages.
Motion of Surface Atoms on Small Gold Particles Revealed by HREM with Real-Time VTR System
Authors: Iijima Sumio , Ichihashi Toshinari
Published: November 2005

A new method of high resolution electron microscopy utilizing a real time VTR-TV monitor system has been developed for the study of small metal particles less than 100 Å in size. The study for the first time revealed the real time motion of the surface atoms on a 100 Å gold cluster. The particle is a cuboctahedron and its {111} and {100} type surface are viewed as their edge-on projections along the <110 > direction. The surface atomic steps are formed on the {100} type surfaces but not on the {111} surfaces. The steps frequently change their positions within less than one tenth of a second. This motion is direct evidence of the random walk of the surface atoms on metal surfaces.
Pulsed Operation of InGaAsP/InGaP Double Heterostructure Visible Lasers Grown by Metalorganic Chemical Vapor Deposition
Authors: Iwamoto Takashi , Mori Kazuo , Mizuta Masashi , Kukimoto Hiroshi
Published: November 2005

Pulsed laser operation of the InGaAsP/InGaP double heterostructure, which was grown on GaAs for the first time by metalorganic chemical vapor deposition, was achieved in the temperature range 100–200 K. The lasing wavelength was 710 nm and the threshold current density was 5.9 KA/cm2 at 100 K. The characteristic temperature T
0 was found to be 67 K.
Ion Induced Auger Electron Emission from Al-Mg Alloy under Low Energy Argon Ion Bombardment
Authors: Yamauchi Yasushi , Ogoh Ikuo , Shimizu Ryuichi , Hashimoto Hatsujiro
Published: November 2005

Ion induced Auger electron emission was investigated by measuring the polar angular distribution for the bulk-like shoulder in the Auger spectrum obeys the cosine law whilst that of the atomic-like peaks shows a spherical distribution, suggesting a model that the former Auger electrons are generated inside the sample and the latter from the sputtered atoms. This model was examined for Al-Mg alloy which showed the surface enrichment of Al. This surface enrichment clearly appears in the ion induced Auger spectrum.
Rapid Thermal Annealing of Si+ Implanted GaAs in the Presence of Arsenic Pressure by GaAs Powder
Authors: Hiramoto Toshiro , Saito Toshio , Ikoma Toshiaki
Published: November 2005

Rapid thermal annealing of Si+ implanted GaAs is carried out using halogen lamps in the presence of arsenic pressure to study the effects of annealing temperature and time on sheet carrier concentration and mobility. The activation efficiency of the implanted layer is primarily affected by the annealing temperature and depends little on the annealing hold time. The surface morphology of GaAs annealed for 30 min at 800°C is smooth, indicating that the presence of arsenic pressure prevents arsenic atoms from evaporating and enables the implanted layer to be annealed for a long time at high temperature without surface dissociation and degradation of electrical properties. The activation energy of implanted Si+ in GaAs is found to be 0.53 eV.
Effects of Error Field on a Reversed Field Pinch Plasma
Authors: Yasuoka Koichi , Tukada Tokuaki , Hayashi Izumi , Kitamura Hiroshi
Published: November 2005

The effects of error fields at a shell gap are measured both optically and magnetically in a Reversed Field Pinch experiment. The measurements show that the increase of poloidal flux consumption is caused by the error fields in the start up phase of discharge. The vertical components of error fields drive the plasma column to the tube wall. In large error fields, the plasma column touches the wall and the plasma current decays quickly.
Linewidth Reduction of a 1.5 µm InGaAsP Laser by Electrical Feedback
Authors: Ohtsu Motoichi , Kotajima Shinichi
Published: November 2005

An electrical feedback technique was proposed for stable reduction of the spectral linewidth of a 1.5 µm InGaAsP laser (DFB type). By controlling the injection current with a servo control circuit of 0.5 kHz∼0.8 GHz bandwidth, the linewidth was reduced by more than five times that of the free running laser. The minimum value obtained here was 2 MHz. Attainable minimum value, which was limited by the shot noise of the detector, was estimated as being 1.0×10-6 times that of the value given by the modified Schawlow-Townes formula.
Laser-Spectroscopic Measurement of Subnanosecond Fluorescence Lifetime of Na 3P Level in Atmoshperic N2 Gas
Authors: Takubo Yoshitaka , Okamoto Tatsuki , Yamamoto Manabu
Published: November 2005

We present the collisional quenching lifetime of Na 3P level in atmospheric N2 gas measured by time-resolved laser-induced fluorescence spectroscopy. This method is a combination of a mode-locked dye laser and a single-photon counting system. The measured lifetime is 0.15±0.02 ns at 800 Torr of N2, and depends linearly on N2 gas pressure below this pressure.
Ar+ Ion Bombardment Effect on Composition Variation in Ni-Fe Film Formed by Ion Beam Sputtering
Authors: Nagai Yasuhiro , Nishimura Chikara , Toshima Tomoyuki
Published: November 2005

This paper reports results of experimental investigations on composition variations in Ni-Fe films formed by ion beam sputtering. The composition variations, depending on both substrate angle and temperature, are caused by high energy Ar+ ions. The Ni fraction in Ni-Fe film and its deposition rate decrease as the ion current increases; this is because of preferential resputtering. Conversely, the Ni fraction increases as the substrate temperature increases without deposition rate change under Ar+ ion bombardment; this has not previously been reported.
Current-Voltage Characteristics of BP p-n Junction
Authors: Yoshida Tohru , Shono Katsufusa , Lee Jong Duk
Published: November 2005

A step (one side) BP p-n junction was formed by B+-implantation and subsequent annealing. A large current density extrapolated to the zero bias can be explained by considering the thermionic emission current over a barrier height of 0.8 volts. The p-BP layer formed by B+-implantation works as a metal electrode, because of the short minority-carrier lifetime of electrons injected into.
Electronic States in Selectively Si-Doped N-AlGaAs/GaAs/N-AlGaAs Single Quantum Well Structures Grown by MBE
Authors: Sasa Shigehiko , Saito Junji , Nanbu Kazuo , Ishikawa Tomonori , Hiyamizu Satoshi , Inoue Masataka
Published: November 2005

Electronic states and transport properties of 2DEG were investigated in selectively Si-doped N-AlGaAs/GaAs/N-AlGaAs single quantum well (SQW) structures grown by MBE. The number of the quantum levels below Fermi energi in the SQW structures varied from one to three with increasing thickness of the GaAs quantum well layer from 60 to 1000 Å. The effect of unintentionally asymmetric Si-doping in the SQW structures due to the surface segregation of Si was found to be essential in explaining the observed results.
Measurements of Potential-Driven Electrostatic Ion Cyclotron Oscillations in a Plasma
Authors: Hatakeyama Rikizo , Muto Fumio , Sato Noriyoshi
Published: November 2005

Temporal and spatial evolutions of plasma parameters are measured during a cycle of electrostatic ion cyclotron oscillations driven by applying a positive potential to a small electrode immersed in a magnetized plasma. The measurements clarify a direct plasma response to the applied potential, confirming a mechanism of two-dimensional potential-driven oscillations.
Emission Characteristics of Au-Si-Be LM Ion Source
Authors: Arimoto Hiroshi , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

Variation of relative fluxes of ion species emitted from a Au-Si-Be liquid metal (LM) ion source with various alloy compositions has been studied for the practical use of the ion source. The Si ion flux (Si++Si++) decreases with an increase in Be concentration because of the reduction of Si solubility in the molten alloy. As the flux of Si ions decreases, the ratio of Si++/Si+ increases remarkably. The mechanism of these phenomena is also discussed.
Intracenter Transition in EL2 Observed in Photocurrent Spectrum
Authors: Tsukada Noriaki , Kikuta Toshio , Ishida Koichi
Published: November 2005

At low temperature (4.2 K) photocurrent spectra of undoped semi-insulating GaAs crystals exhibit an extra band centered at about 1.17 eV and a fine structure between 1.04 and 1.10 eV. These structures are virtually identical to those of the optical absorption spectra recently reported by Kaminska et al., who claimed that they are ascribable to the intracenter transitions in EL2, because the structures are never observed in their photocurrent spectra. We discuss the cause of inconsistency between their result and ours and also some mechanisms in which the intracenter transition in EL2 is observed in the photocurrent spectrum.
Giant Resistivity Anomaly in A15 Nb3(Ge, Si) Superconductive Films with Compositionally Modulated Superstructure
Authors: Yamamoto Hiroshi , Ikeda Masanori , Tanaka Masaichi
Published: November 2005

A15 Nb3(Ge, Si) films with compositionally modulated superstructure have been synthesized by sputtering from rotated targets. Some of the films exhibit a remarkable maximum of resistivity in the vicinity of the onset temperature of superconductive transition between 7 K and 19 K on the abscissa, when the dc current in the resistivity measurement is low enough. The resistivity peak height vs current plots are similar to those for the giant resistivity anomaly recently observed on TaSe3. The anomaly seems closely correlated to the multilayered structure containing ultrathin superconductive layers.
New Center Formation in Silver Halide Crystals Doped with Sulphur
Authors: Nagashima Toshio , Sonoike Sanemi
Published: November 2005

It is reported that a new center is formed in silver halide crystals doped with sulphur by pulse annealings above 300°C after exposure to light at room temperature. The excitation spectra of the centers well fit with the Mollwo-Ivey line for the F centers in alkali halides. The center is suggested to be an F center produced from S2--halogen-vacancy complexes.
DLTS Study of Pulsed Ruby Laser Irradiation Effects on n-CdTe
Authors: Tomitori Masahiko , Kuriki Makoto , Ishii Sugio , Fuyuki Shigeru , Hayakawa Sohachiro
Published: November 2005

DLTS measurements were carried out for Au/n-CdTe junctions which were formed on surfaces irradiated by a pulsed ruby laser. Electron trap levels at 0.65 eV and 0.83 eV below the conduction band were induced in high concentration by the irradiation of more than 0.8 J/cm2energy density. The irradiation of 0.3 J/cm2improved the characteristics of Schottky junction of Au/n-CdTe and ohmic contact of In/n-CdTe.
A New p-Channel AlGaAs/GaAs MIS-Like Heterostructure FET Employing Two Dimensional Hole Gas
Authors: Oe Kunishige , Hirano Makoto , Arai Kunihiro , Yanagawa Fumihiko
Published: November 2005

A new p-channel two dimensional hole gas (2DHG) heterostructure FET (HFET) which operates in MIS transistor-like mode has been fabricated on an undoped AlGaAs/GaAs heterostructure grown by molecular beam epitaxy (MBE). The device operates entirely in an enhancement-mode with a threshold voltage of -0.3 V at both 300 K and 77 K. Maximum values of transconductances of 17 ms/mm at 300 K and 40 mS/mm at 77 K have been achieved in a 1 µm gate length structure. As the present p-channel device is very simple, a complementary circuit scheme using a p-channel 2DHG HFET of this type will be most promising in future.
Iodine Atoms Structured in (SN)x
Authors: Isoda Seiji , Kawaguchi Akiyoshi , Uemura Akio , Katayama Ken-ichi
Published: November 2005

Electron diffraction pattern of iodinated (SN)
x
shows that iodine atoms are structured as a chain along the molecular axis of (SN)
x
. High resolution electron micrograph and its optical transform show that the crystalline lattice is severely distorted by iodination, but the (1̄02) plane is comparatively stable for iodine invasion. Iodine atoms are considered to be settled on the (1̄02) plane, where iodine atoms are structured as iodine chains and the two iodine chains tend to pair.
Role of Line and Continuum Opacities in X-Ray Transmission Through A Laser-Heated Au Foil
Authors: Yabe Takashi , Kiyokawa Syuji , Nishimura Hiroaki , Yamanaka Chiyoe
Published: November 2005

The roles of line and continuum opacities in laser-heated high-Z plasmas are investigated by comparing the non-LTE simulation with the experiment. The line opacity is found to critically determine mass ablation rate, whereas the continuum opacity determines X-ray transmission only in a high density region. The Bloch-type hydrodynamic model for photoionization gives a more acceptable result than the average ion model.
Mass and Energy Analyses of Gallium-Indium Liquid-Metal-Ion Sources
Authors: Ishitani Tohru , Umemura Kaoru , Tamura Hifumi
Published: November 2005

Mass and energy analyses of ions emitted from Ga-In alloy LMI sources were carried out using a double-focusing mass spectrometer to compare these data with those from single-element Ga and In LMI sources. A more distinct low energy shoulder was observed on the Ga+energy distribution curve for the Ga-In source at the lower source-current and the higher emitter temperature. A similar shoulder was also observed for the Ga source but not for the In source. The Ga shoulder for the Ga-In source suggests Ga preferential vaporization at the emitter and/or Ga preferential ionization in the vicinity of emitter.
Substrate Current of Submicrometer Buried-Gate MOSFET
Authors: Ikeda Hiroshi
Published: November 2005

A buried-gate MOSFET is proposed for submicrometer devices, especially for 1/4 micrometer level devices. In this structure, reduced short channel effects are shown and very shallow junctions are not required. The results of two-dimensional device simulation indicate that the buried-gate MOSFET shows less substrate current than conventional MOSFET for low gate voltages and different gate voltage dependence of the substrate current.
Recovery Effect of Deep Level Luminescence Induced by Below Band-Gap Excitation in GaAs
Authors: Tajima Michio
Published: November 2005

New photoluminescence (PL) recovery effects induced by below band-gap excitation have been observed for the fatigued emission bands associated with the deep donor EL2 in undoped semi-insulating liquid encapsulated Czochralski-grown GaAs crystals. The PL intensity quenched by a pre-excitation with a 1.06-µm light is restored gradually by a persistent irradiation of the same 1.06-µm light with a reduced excitation intensity in some samples and by a 1.32-µm light in all the samples. These recovery effects are explained by the occurrence of optical transition from the metastable state to the normal state of the EL2 level.
Surface Stoichiometry and Morphology of MBE Grown (001)GaAs through the Analysis of RHEED Oscillations
Authors: Briones Fernando , Golmayo Dolores , Gonzalez Luisa , Miguel José Luis De
Published: November 2005

Analysis of RHEED oscillations under static conditions and during MBE growth has been used to study the surface departure from stoichiometry and related microscopic morphology for the As-stabilized 2×4 (001)GaAs surface reconstruction when substrate temperature and arsenic pressure are systematically varied. Specular beam intensities under static conditions are related to the first transient peak and phase shift of the oscillations during growth. Phase shifts are linear with the logarithm of arsenic pressure and depend on substrate temperature with an activation energy of 3.2 eV in the same way as surface stoichiometry. A discussion of the results based on a surface morphology model is presented.
Periodic Surface Energy Driven Single Crystallization on Flat Surface
Authors: Egami Koji
Published: November 2005

This letter demonstrates the single crystallization of thin films on unordered substrates (amorphous materials) with a discrete surface energy distribution, even if the substrate surface is flat. This crystallization, called periodic surface energy driven single crystallization, arises from the periodic stripe patterns of different materials with different surface energy. An example that facetted KCl single crystals can be grown on the SiO2-Si3N4 stripe patterns is shown.
Correlation between Mode Fluctuations in a Semiconductor Laser
Authors: Akabane Hideo , Tsuchiya Tohru , Kawakubo Tatsuyuki , Abe Hideaki
Published: November 2005

The correlation between fluctuations of different modes of a single mode semiconductor laser has been measured at several temperatures. The lasing mode is found to have a strong coupling with its adjacent nonlasing modes, but the coupling is exceptionally weak if the adjacent mode does not become a lasing mode when the temperature is changed.
Comparison of Sorption Process in Titanium and Vanadium Films
Authors: Konishi Ryosuke , Miyada Yoshinori , Sasakura Hiroshi
Published: November 2005

We observed the sorption process of hydrogen atoms beneath titanium and vanadium films using an electrical resistance method, AES and AEAPS.
Applying Toya's theory to our measurements of the resistance, we may derive that both r- and s-type adsorption states exist in titanium films, whereas only the r-type state seems to be present in vanadium films. From the results of AES and AEAPS, we may assume that the V-H bond is formed beneath the metal surface as is the Ti-H bond; nanely, the r-type adsorption state in the vanadium films is apparently present beneath the metal surface as well as the s-type adsorption state in the titanium films.
Compositional Disordering of GaAs-AlxGa1-xAs Superlattice by Ga Focused Ion Beam Implantation and its Application to Submicron Structure Fabrication
Authors: Hirayama Yoshiro , Suzuki Yoshifumi , Tarucha Seigo , Okamoto Hiroshi
Published: November 2005

Using a focused ion beam technology, Ga ion is implanted into a GaAs-Al
x
Ga1-x
As superlattice epitaxial wafer. The compositional disordering of the superlattice occurs during an annealing after ion-implantation. Interdiffusion coefficient of Ga and Al is measured from the photoluminescence peak energy shift as a function of annealing time and the result shows that it is as large as that for Si ion implanted superlattice. By line-and-space scan of the Ga ion beam, a submicron periodic structure of the superlattice and the mixed crystal is fabricated over the epi-wafer and examined by low temperature cathodo-luminescence topography.
Transient Characteristics of Photoluminescence from GaAs/Ga0.7Al0.3As Single Quantum Well Structure
Authors: Miyoshi Tadaki , Aoyagi Yoshinobu , Segawa Yusaburo , Namba Susumu , Nunoshita Masahiro
Published: November 2005

Transient characteristics of luminescence from single quantum well (SQW) structure have been examined using a time-correlated single photon counting method. The decay time of the SQW luminescence is shorter than that of bulk sample. The rapid decay is considered to reflect the enhancement of recombination due to localization of excitons. The disagreement between the present results and those reported by other researchers is discussed.
Room Temperature Operation of Visible (λ=658.6 nm) InGaAsP DH Laser Diodes on GaAsP
Authors: Fujii Sadao , Sakai Shiro , Umeno Masayoshi
Published: November 2005

A suitable GaAs1-z
P
z
substrate composition (z) for InGaAsP double heterojunction laser diodes is discussed. In1-x
Ga
x
As1-y
P
y
(x=0.83, y=0.64)/In1-x'Ga
x'As1-y'P
y' (x'=0.67, y' ≧0.98) laser diodes fabricated on GaAs1-z
P
z
(z=0.3) substrate by a two-phase-solution technique operated under pulsed conditions at room temperature. The peak wavelength and the threshold current density (J
th) were 658.6 nm and 12 kA/cm-2, respectively. This J
th is lower than in the previously reported planer type laser diodes fabricated from the same material system.
Far Infrared Spectroscopy by the Fabry-Perot Interferometer V
Authors: Yoshihara Kunio , Zhao Bao-Chang
Published: November 2005

The spectrum of radiation is reconstructed from the multiple-beam interferogram of the Fabry-Perot interferometer by the general method of Hilbert and Schmidt even when the reflectivity of the reflecting surfaces varies with wavenumber, and consequently the kernel of the integral equation is not symmetric. The instrumental function has infinitely narrow width, as before. The effect of noise on the reconstructed spectra is greater than in Fourier spectroscopy, but the reconstruction is not seriously disturbed in practice.
Transient Response of Photoluminescence for Electric Field in a GaAs/Al0.7Ga0.3As Single Quantum Well: Evidence for Field-Induced Increase in Carrier Life Time
Authors: Yamanishi Masamichi , Usami Yuichi , Kan Yasuo , Suemune Ikuo
Published: November 2005

Transient photoluminescence measurements for pulsed electric field at room temperature on a GaAs/AlGaAs single quantum well structure have been carried out to clarify the field-dependence of the recombination life time of carriers. The life time increases with the increasing electric field in a marked contrast to the previously reported results. The present results are consistently explained in terms of the field-induced reduction in the overlap between the electron and hole wave functions inside the GaAs well.
Electric Field Effect on Subband State Transitions Peaks in the Photoluminescence from a GaAlAs Quantum Well Structure
Authors: Kan Yasuo , Yamanishi Masamichi , Suemune Ikuo , Yamamoto Hiroaki , Yao Takafumi
Published: November 2005

Photoluminescence measurement on a GaAlAs quantum well structure subjected to an electric field has been performed. The photoluminescence peak is remarkably shifted to the lower energy side with increasing field. Moreover, the difference in the field-induced polarization effect between heavy and light holes is clearly observed in the photoluminescence spectra. The n=1 electron and heavy hole rtransition spectrum shows a more sensitive response to an electric field than n=1 electron and light hole one. The experimental result is successfully explained in terms of the field-induced carrier separation model.
Influences of AlGaAs Emitter Band Gaps on Current Gains in AlGaAs/GaAs HBTs
Authors: Ito Hiroshi , Ishibashi Tadao
Published: November 2005

The influences of an emitter Al content on current gains in AlGaAs/GaAs heterojunction bipolar transistors are investigated experimentally. In the HBTs examined, a linearly graded band-gap base with heavy doping of 1×1019 cm-3 is utilized, in which the AlAs mole fraction at the emitter-base interface is 0.1. Current gain increases from 6 to 68 for emitter Al content from 0.1 to 0.3. Experimental results are compared with the calculation, including Fermi-Dirac carrier distribution, band-gap shrinkage, and diffusion and drift transport in the base. The Al content difference between emitter and base junction necessary for obtaining sufficient current gain value is found to be approximately Δ
x= 0.1.
Observation of Striations in Nd: YAG with Circularly Polarized Light
Authors: Hayakawa Hirohiko , Umino Masami , Mori Hiroshi , Fujii Yoshimasa
Published: November 2005

Birefringence associated with growth-striations of Nd-doped yttrium aluminum garnet crystals (Nd: YAG) was measured along the growth direction by using circularly polarized light and an auto-scanning stage. This allowed precise measurement of the magnitude of birefringence of the order of the 10-6. The residual strain and the fluctuation of the Nd concentration are determined by a model in which the stress birefringence is caused by the lattice-mismatch due to the compositional change at striations. Two main origins of the compositional change are proposed.
A New One-Dimensional Long Period Superstructure in Pd5Ce
Authors: Kuwano Noriyuki , Higo Shinji , Yamamoto Keisuke , Oki Kensuke , Eguchi Tetsuo
Published: November 2005

The crystal structure of Pd5Ce phase has been analyzed by X-ray diffraction and electron microscopy. It is revealed that the Pd5Ce has two phases, one stable at low temperature and the other at high temperature. The structure of the low temperature phase is identified as a kind of long period antiphase structure with fcc fundamental cells.
Direct Pattern Fabrication of Substituted Phthalocyanine Films
Authors: Tabei Hisao , Fujiki Michiya , Imamura Saburo
Published: November 2005

A new technique for high resolution lithography of phthalocyanine molecules is described. The phthalocyanine substituted with long chain alkyl amide groups was found to show good solubility in chloroform and the phthalocyanine films show good sensitivity to electron beams (Dn
0.5=6.8 µC/cm2), with a contrast value of γ=1.6, and with semiconductivities (<10-6 S/cm).
Photo-Electron Paramagnetic Resonance Study of AsGa Antisite Defect in As-Grown GaAs Crystals of Different Stoichiometry
Authors: Tsukada Noriaki , Kikuta Toshio , Ishida Koichi
Published: November 2005

The photoresponses of the antisite defect AsGa
+ electron paramagnetic resonance signal have been investigated in as-grown, undoped, semi-insulating GaAs crystals grown from melts of different As atoms fractions. The observed photoresponses are well explained by assumting that the AsGa antisite and the deep donor EL2 have identical photoionization cross sections and their concentrations exhibit the same dependence on melt stoichiometry. We have also reported the first observation of an extra singlet superimposed on the third component of the AsGa
+ quadruplet in as-grown GaAs. The photoresponse of the singlet is very different from that of the AsGa
+ quadruplet.
Optoelectrical Properties of Hydrogenated Amorphous Silicon-Polycrystalline Cadmium Telluride Heterojunctions
Authors: Mimura Hidenori , Kajiyama Shigetoshi , Nogami Minoru , Hatanaka Yoshinori
Published: November 2005

Optoelectrical properties of heterojunctions consisting of hydrogenated amorphous silicon (a-Si:H) and polycrystalline cadmium telluride (pc-CdTe) have been investigated in current-voltage characteristics and spectral photoresponses. It was found that the a-Si:H/pc-CdTe heterojunctions had depletion layers on both sides of a-Si:H and pc-CdTe and provided a high and flat photosensitivity over the wavelength range from 400 to 850 nm. These results hold promise for application to a highly efficient solar cell and a photo-sensor.
Metal Precipitation in Transparent Layer Ionic Crystals (CnH2n+1NH3)2MCl4 with n=1, 2 and M=Mn, Cd
Authors: Yoshinari Takehisa , Matsuyama Tomochika , Yamaoka Hitoshi , Aoyagi Kiyoshi
Published: November 2005

Layer ionic crystals (C
n
H2n+1NH3)2MCl4 with n=1, 2 and M=Mn, Cd have been irradiated with X- or γ-rays at 77 K. After warming the crystals up to room temperature, metallic luster as a silver mirror has been observed in them. Taking into account optical absorption spectra and elimination of chlorine from the crystals, it is concluded that the metallic luster is caused by metal precipitation in the crystals. The mechanism of the precipitation is considered with the concept of color center formation and destruction in low dimensional crystals.
Photothermal Interference Spectroscopy
Authors: Hoshimiya Tsutomu
Published: November 2005

A new spectroscopic measuring scheme, photothermal interference spectroscopy (PIS), has been proposed, analyzed and demonstrated for the first time. A sample under study is set in one of the arms of a Mach-Zehnder interferometer, and its refractive index is modulated by a periodically modulated pump laser beam. A signal dependence on a sample concentration is proportional to the product of the trigonometric function and the Bessel function. Applications of this method to gas monitoring and to gas and liquid chromatographies are also discussed.
High Rate and Low Temperature Deposition of Co-Cr Films by Exposed Pole Magnetron Co-Sputtering System
Authors: Takahashi Takakazu , Miyata Tsutomu , Yoshida Junsaku , Hata Tomonobu
Published: November 2005

Co-Cr films were successfully deposited using the exposed pole (EP) magnetron co-sputtering system, obtaining a larger leakage magnetic field, at a high rate (1400 Å/min) and a low substrate temperature (70°C) for a power density of 7.6 W/cm2. Differences in the radial profiles of film thickness and Co content in the films were as small as 17% and 5 wt.%, respectively within a 70 mm diameter of the films. The target utilization efficiency at the surface is more than 85 %. The films have a c-axis orientation of Δθ50=8–10^° and a perpendicular magnetization of M
s
⊥=550–670 emu/cc and H
c
⊥=250–300 Oe to the film plane.
High Spatial Resolution Spin-Polarized Scanning Electron Microscope
Authors: Koike Kazuyuki , Matsuyama Hideo , Todokoro Hideo , Hayakawa Kazunobu
Published: November 2005

Spatial resolution of a spin-polarized scanning electron microscope has been improved to 0.2 µm for domain images of an iron sample. This value is comparable to that of the colloid-SEM (scanning electron microscope) method and is superior to that of other conventional reflection-type domain observation methods. This spin-polarized scanning electron microscopy is an excellent method for surface magnetic domain observation, due to not only high spatial resolution but also its other capabilities which conventional methods including the colloid-SEM method do not have.
Growth Condition Independence Observed for DX Center in Si-doped AlGaAs Grown by Molecular Beam Epitaxy
Authors: Ashizawa Yasuo , Watanabe Miyoko Oku
Published: November 2005

Growth condition dependence of donor levels in Si-doped Al0.3Ga0.7As grown by molecular beam epitaxy has been studied by DLTS, C-V and low temperature (4.2 K) photoluminescence measurements. Concentration ratio of shallow donor to total donor is independent of growth temperature and group V/III flux ratio. This suggests that DX center is dominated only by AlAs mole fraction.
Observation of the Persistent Photoconductivity Due to the DX Center in GaAs under Hydrostatic Pressure
Authors: Tachikawa Masami , Fujisawa Toshimasa , Kukimoto Hiroshi , Shibata Akio , Oomi Gendo , Minomura Shigeru
Published: November 2005

Persistent photoconductivity due to the DX center in GaAs under a hydrostatic pressure of about 30 kbar has been observed for the first time. The characteristic temperature-dependent photoconductivity observed in GaAs under pressure is quite similar to that in AlGaAs alloy system. This indicates that the DX center in GaAs under hydrostatic pressure has also a large lattice relaxation owing to the AlGaAs-like conduction band structure.
Composition Dependence of Equal Thickness Fringes in an Electron Microscope Image of GaAs/AlxGa1-x As Multilayer Structure
Authors: Kakibayashi Hiroshi , Nagata Fumio
Published: November 2005

A new method is presented for the composition analysis of GaAs/Al
x
Ga1-x
As multilayer structure using transmission electron microscopy. It is found that the position of equal thickness fringe observed at the edge of a cleaved chip is closely related to the composition. Change in Al composition in GaAs/Al
x
Ga1-x
As superstructure is observed as a shift of the equal thickness fringe. Compositional abruptness at the heterointerface and compositional fluctuation in the thin layer can be estimated in the electron microscope image.
High Devitrification Growth Rate in As-Doped Oxide Film on Silicon-Dioxide Layer
Authors: Tsunoda Yoshihiro
Published: November 2005

Devitrification growth rates in As-doped oxide films on SiO2 substrates were measured using an optical microscope. Comparisons were then made with growth rates on Si and Si3N4 substrates. Subsequent to heat-treatment at 1050°C, 1100°C, and 1150°C, it was found that devitrification rates on SiO2 substrates were higher than those on Si and Si3N4 substrates. From the relation between devitrification growth size and heating time on three kinds of substrates, it has been concluded that the devitrification growth rates in As-doped oxide films depend both on the values of activation energies, and of incubation periods.
X-Ray Standing Wave Method Applied to the Characterization of InGaAsP Alloy Semiconductor Thin Film
Authors: Akimoto Koichi , Ishikawa Tetsuya , Takahashi Toshio , Kikuta Seishi , Matsui Junji
Published: November 2005

The X-ray standing wave method was applied to the characterization of InGaAsP thin film epitaxially grown on an InP substrate. The yields of Ga Kα and As Kα fluorescent X-rays were measured around the Bragg angle of both 200 and 400 reflections. By comparing the profiles of the experimental yield curves with those of calculated ones, it was shown that the atomic sequence of Group III and Group V elements at the interface was an alternating one, as expected. The amount of lattice mismatch was also discussed.
Growth and Properties of Low-Resistivity n-Type ZnSe Crystals Grown from the Melt with Excess Zn under Argon Pressure
Authors: Kikuma Isao , Furukoshi Mitsuo
Published: November 2005

This paper describes a technique for growing low-resistivity n-type ZnSe crystals from the melt under pressure and the electrical and optical properties of the crystals. The low-resistivity ZnSe crystals are grown from the melt with excess Zn of 3 to 9.3 mol%. The resistivity of the crystals is of the order of 0.1 Ω·cm and the electron Hall mobility is 220 to 380 cm2/Vs. Near-band-edge emission is observed from the low-resistivity ZnSe crystals at room temperature in photoluminescence measurement.
Cathodoluminescence of Ga2(S0.73Te0.27)3
Authors: Iwamura Yasuo , Negishi Hitoshi , Moriyama Makoto
Published: November 2005

Intense and stable orange cathodoluminescence emission is discovered in Ga2(S0.73Te0.27)3 at room temperature. Solid solutions of the Ga-S-Te system were grown by the closed tube chemical transport method using GaI3 as a transporting agent. Intensity of the cathodoluminescence increases linearly with an incident electron beam current, and with an accelerating voltage. The line-shape of the spectrum is broad and independent of the condition of the incident beam. The peak wavelength is 6900Å and corresponds to the energy gap, 1.80 eV, obtained from the optical transmission measurement.
Current and Field Characteristics and Memory Mechanism of TFEL Devices
Authors: Onnagawa Hiroyoshi , Shibata Miki , Miyashita Kazuo
Published: November 2005

The apparent current-controlled negative resistance resulting from current and triangular voltages in memory and nonmemory devices is considered to be due to hot electron injection fom the ZnS layer into the insulating layer. Further studies of the current wave in memory devices has revealed a voltage-controlled negative resistance. This fact is used to construct a two-level model of primary electron sources for impact excitation to explain the memory behavior of such devices. The model takes account of the interface state for initial high-field excitation and the trap level for sustaining low-field excitation.