bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of EXAFS Spectrometer and Structural Characterization of Amorphous Silicon
Authors: Nishino Yoichi , Takano Yukio
Published: November 2005

The design features and performance of an EXAFS (Extended X-ray Absorption Fine Structure) spectrometer are presented. This device allows soft X-ray absorption experiments for structural studies of thin films composed of light elements such as silicon. The spectrometer is equipped with a totally reflecting mirror to reduce the intensity of higher harmonics to about 1% of that of the fundamental. The application of the spectrometer to amorphous silicon has shown that an increment in the deposition rate gives rise to a larger magnitude of the first peak in the radial distribution, indicating the formation of a more ordered phase during deposition.
Multiple Scattering Correction to the Channeling Surface Peak for Thin Overlayers
Authors: Ito Toshimichi
Published: November 2005

The multiple-scattering contribution to the surface peak for MeV ion channeling studies of crystals covered with thin films (< 50 Å thick) can be experimentally subtracted since it is expressed in the form of an approximate error function. The method is based on experimental observations and computor calculations. Monte Carlo simulations give precise angular variations of the backscattering probabilities of probing ions from substrate atoms and angular distribution of incident particles after the passage of probing ions through a thin amorphous overlayer. The proposed method requires coverage-dependent signals in an energy region well behind the surface peak, where the spectrum height increases proportionally with film thickness. The limitations of the present method, including the case of substrate intermixing at the interface, are discussed.
On the Origin of Oval Defect with Nucleus on Epilayers Grown by Molecular Beam Epitaxy
Authors: Nishikawa Yasumi , Kanamoto Kyozo , Tokuda Yasunori , Fujiwara Kenzo , Nakayama Takashi
Published: November 2005

By careful cross-sectional and surface observations of an oval defect with a macroscopic nucleus on epilayers grown by molecular-beam epitaxy, the origin was identified to be macroscopic surface contamination.
Characterization of Cu/Ti Multi-Layered Structure by Improved Sputter Crater Method
Authors: Hatano Takeshi , Nakamura Keikichi , Asada Yuji , Ogawa Keiichi , Oguchi Atsushi
Published: November 2005

Layered Cu/Ti superlattice structures have been studied by an improved sputter crater method. A low-energy and large-area rastering Ar-ion beam was intensitionally used to produce a shallow and homogeneously etched crater. The Cu and Ti layers 10-20 Å thick could be observed as concentric circles with a magnification factor (lateral/depth) of 104∼105.
On Optical Absorption in Semiconducting KTa0.87Nb0.13O3
Authors: Tsukioka Masayuki , Nagata Eiji , Ehara Shaw , Tanaka Junzo
Published: November 2005

In order to investigate the source of the optical absorption observed in some semiconducting oxides in the nearinfrared region, measurements of the optical absorption, photoconduction, electrical resistivity and Hall coefficient were carried out in semiconducting KTN. From these experimental results, it is concluded that the intense optical absorption was not due to conduction electrons.
Practical Expression for Reflectances of GaP
Authors: Endo Tamio , Taniguchi Shizuo , Yamanaka Tohru , Kamota Masanori , Sugiyama Koichi
Published: November 2005

A practical expression for reflectances below the energy gap of GaP was determined from measured reflectances in the region of visible light at 300 K by the Kramers-Kronig technique. The temperature dependence of the reflectances was taken into account in the expression.
Optical Properties of Cd3InGaS6
Authors: Irie Taizo , Endo Saburo , Kurogane Hideo , Nakanishi Hisayuki , Toyoda Taro
Published: November 2005

The optical absorption and photoluminescence spectra of Cd3InGaS6 were measured. It was found that Cd3InGaS6 has a direct energy gap of 2.43 eV at room temperature. When excited with photons at 2.54 eV at low temperatures, an intense green emission at 2.38 eV and a red emission at 1.7 eV were observed. The time-resolved spectra indicate that the green emission at 2.38 eV is due to donor-to-acceptor transitions.
Volume Change due to Intermetallic Compound Formation at the Al-Au Bond in Semiconductor Devices
Authors: Kato Hiroshi
Published: November 2005

The molar volume of an Al-Au intermetallic compound was calculated and compared with those of Al and Au individually. It is well known that, though the molar volume of an AlAu4 compound is smaller than the sum of those of Al and Au, it is larger than that of Al. It is shown that this fact can be explained by taking into consideration the differences between the densities of Al, Au and Al-Au alloys and the component ratio of the compound. Practically, it is pointed out that this volume effect can induce pores at an imperfect bond between Al films and Au wires in Si devices. This suggests that such partial openings should be distinguished from Kirkendall voids.
Emission Cross Sections of Excited Fragments Produced by 0-100 eV Electron Impact on SiH4: Application of the “He Standard”
Authors: Sato Toshihiko , Goto Toshio
Published: November 2005

The emission cross sections of excited fragments, SiH(A2Δ-X2∏), H Balmer lines and Si I, II lines produced from SiH4 by electron impact were obtained in an energy range below 100 eV. The performed measurements were based on the “He standard”. The uncertainties of the obtained values were estimated to be less than 12%.
The emission cross section of the Si I(4s1Po-3p21D) singlet was shown to be almost the same magnitude as that of the Si I(4s3Po-3p23D) triplet in contrast with the result obtained from a VUV photolyses of SiH4. The freatures of the optical excitation functions of the atomic fragments were explained in terms of the “ionic core” model.
Molecular Beam Epitaxial Growth of GaAs with Arsenic Molecules Transported by Hydrogen Gas
Authors: Sugiura Hideo , Kawashima Minoru , Horikoshi Yoshiji
Published: November 2005

GaAs films have been grown in an ultra-high vacuum chamber using molecules transported by a hydrogen carrier gas. The hydrogen gas flow rate through a heated arsenic cell varied over a range of 0.3-100 cm3/min. This corresponds to a background hydrogen gas pressure range of 1×10-6∼3×10-3 Torr. Arsenic was clearly transported from the heated arsenic ingot to the substrate surface when the hydrogen gas flow rate was greater than 5 cm3/min. This suggests the possibility of a more precise arsenic pressure control. The low-temperature photoluminescence spectra of these GaAs films reveal that hydrogen gas flow effectively reduces acceptor type impurities in the crystals.
Changes of Structural, Electrical, and Optical Properties of Microcrystalline SixGe1-x Films by Annealing
Authors: Kohno Kenji , Iwaoka Teiji , Nakashima Toshio , Imura Takeshi , Osaka Yukio
Published: November 2005

The dependence of the structural, electrical and optical properties on annealing was investigated for microcrystalline films of a Si
x
Ge1-x
alloy prepared by the sputter-assisted-plasma CVD method. An essential morphological change by annealing below 700°C was not found by a TEM observation. ESR and IR absorption measurements, however, suggested that the network in a grain-boundary zone was reconstructed upon annealing above 400°C. The activation energy of dark conductivity had a close connection with the states of a Ge dangling bond and a donor-like defect.
Interpretation of Capacitance-Voltage Profiles from Delta-Doped GaAs Grown by Molecular Beam Epitaxy
Authors: Schubert E. F. , Ploog K.
Published: November 2005

Molecular beam epitaxy allows to grow narrow doping profiles which are described by the Dirac-delta function. Ionized impurities of delta(δ)-doped GaAs layers form a V-shaped potential well. Capacitance-voltage (C
V) measurements on δ-doped GaAs with two-dimensional donor concentrations of N
D
2D=4-6×1012 cm-2 performed at 77 and 300 K show a maximum C
V-concentration of 6.8×1018 cm-3 and a full-width at half-maximum of 46 Å, which does not depend on the sample temperature. A new theoretical model of C
V-profiles from δ-doped GaAs is presented which takes into account the quantum-size effect. The quantum-mechanical interpretation of the C
V-profiles shows that the measured profiles reflect neither the dopant concentration nor the free-carrier concentration. The C
V-profiles reflect the shift of the electron wavefunction in the V-shaped potential well, which is tilted by the applied voltage. A good agreement between calculated and measured C
V-profiles is found.
Electron Emission Properties and Surface Atom Behavior of an Impregnated Cathode Coated with Tungsten Thin Film Containing Sc2O3
Authors: Yamamoto Shigehiko , Taguchi Sadanori , Watanabe Isato , Kawase Susumu
Published: November 2005

A new cathode has been developed which shows similar electron emission characteristics as a previously reported Sc2O3 mixed matrix impregnated cathode (Sc2O3 MM Cathode). Contrary to the Sc2O3 MM cathode, the new cathode is resistive to prolonged heating at high temperatures and to ion bombardment. This has been made possible by applying to a standard impregnated cathode a tungsten thin-film containing about 5 weight percent Sc2O3. The electron-emission property is found to be strongly linked to the surface atom composition as well as to the distribution of surface atoms.
Synthesis of A15 Nb-Si Films on Si-Precoated Substrate Using Dual-Target Sputtering
Authors: Nakamura Kiko , Takei Koji , Maeda Yasushi
Published: November 2005

This paper describes metastable A15 Nb-Si films synthesized by dual-target dc-magnetron sputtering. The approximate 40-Å Si precoating on a surface of sapphire substrates is found to greatly affect the suppression of a competing stable Ti3P-type phase formation. It is confirmed that T
con (1% onset of superconductivity) > 13 K films can be prepared with good reproducibility using compositional grading. The crystal growth of A15 Nb-Si films on Si-precoated substrates is investigated and a model for A15 film growth is presented.
Formation of GaAs-on-Insulator Structures on Si Substrates by Heteroepitaxial Growth of CaF2 and GaAs
Authors: Asano Tanemasa , Ishiwara Hiroshi , Lee Hee Chul , Tsutsui Kazuo , Furukawa Seijiro
Published: November 2005

Epitaxial GaAs layers have been grown on (100) and (111) oriented CaF2/Si structures by molecular beam epitaxy, and characterized mainly by ion channeling and cross-sectional transmission electron microscopy. GaAs films were found to grow epitaxially at conventional growth temperatures (≤600°C). GaAs films having better crystalline quality could be grown on (111) substrates, though the surface of these GaAs films was not flat. Planar defects were peculiarly observed in GaAs films grown on (100) substrates.
Anodic Oxidation of Zinc Phosphide
Authors: Suda Toshikazu , Murata Yoshitada , Kurita Shoichi
Published: November 2005

Initial stages of a native oxidation on Zn3P2 by anodization have been investigated for the first time using 3% tartaric acid/propylene glycol electrolyte. A constant-current anodization is found to be superior to a constant-voltage anodization because of the rapid growth of the initial stage in the constant-voltage mode in view of controlling thin oxide layers. The surface composition of anodized Zn3P2 was examined by AES and XPS. The oxide layer was identified as a mixture of ZnO, P2O5, and P2O3: the increased [P2O5+P2O3]/[ZnO] ratio of ∼ 1.3 was obtained at acidic and basic pH values, whereas the composition ratio was ∼ 0.2 near a neutral pH value as a result of selective dissolution of either ZnO or PO
x
.
Precise Control of Resonant Tunneling Current in AlAs/GaAs/AlAs Double Barrier Diodes with Atomically-Controlled Barrier Widths
Authors: Tsuchiya Masahiro , Sakaki Hiroyuki
Published: November 2005

The resonant tunneling current is studied in AlAs/GaAs/AlAs double barrier heterostructures in which the barrier widths L
B are precisely controlled to be exactly 5, 8 and 11 atomic monolayers. It is demonstrated for the first time that the density of resonant current in these diodes can be controlled from 5×102 Acm-2 to 1.2×104 Acm-2 by the choice of L
B, in accordance with the theoretical calculations. Furthermore, I–V characteristics of these devices are shown to be excellent with peak-to-valley ratios of 2.3 at room temperature and 10 at 80 K, the highest values ever reported.
Comment on “Intracenter Transition in EL2 Observed in Photocurrent Spectrum”
Authors: Lagowski J. , Skowronski M. , Gatos H. C.
Published: November 2005

Low temperature photocurrent spectra of undoped semi-insulating GaAs reported recently by Tsukada et al. were claimed to be virtually identical to those of optical absorption spectra published by Kaminska et al. This claim is unfounded, as the two types of spectra were systematically different, and accordingly the interpretation of the subject photocurrent spectra is erroneous.
Reply to “Comment on `Intracenter Transition in EL2 Observed in Photocurrent Spectrum'”
Authors: Tsukada Noriaki , Kikuta Toshio , Ishida Koichi
Published: November 2005

In order to examine the propriety of the claim by Lagowski et al., the simultaneous measurements of optical absorption and photocurrent were performed with undoped semi-insulating GaAs crystals. The experimental results show that both optical absorption and photocurrent spectra at low temperature are systematically identical with respect to the structures of zero-phonon-line and its phonon replicas and the intracenter transition band of EL2. Accordingly, it is concluded that the intracenter transitions in EL2 lead to generation of free carriers.
Conical Liner Implosion as a Projectile Injector for Mass Drivers
Authors: Ikuta Kazunari , Kristiansen Magne
Published: November 2005

An electro-magnetic method for injecting a projecting a projectile into a mass driver using a conical liner in proposed.
Molecular Selective Pre-Tilt on Glass Surfaces and Color Difference between Two Twisted States in Surface Stabilized Ferroelectric Liquid Crystal Cells
Authors: Shingu Toshiaki , Tsuchiya Tsuyoshi , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo
Published: November 2005

Transmission spectra and chromaticities of surface stabilized states were numerically calculated by Berreman's 4×4 matrix method. It was found that molecular selective pre-tilt on both glass surfaces causes a color difference between two twisted states distinguished by the sense of C-director rotation. These colors alternate with each other when a cell is rotated by the apparent cone angle under crossed Nicols. This is consistent with the experimental observation. In relatively thin cells, the existence of the pre-tilt gives a contrast instead of a color difference.
Raman Image Measurements of Laser-Recrystallized Polycrystalline Si Films by a Scanning Raman Microprobe
Authors: Nakashima Shin-ichi , Mizoguchi Kohji , Inoue Yasuo , Miyauchi Michihiro , Mitsuishi Akiyoshi , Nishimura Tadashi , Akasaka Yoichi
Published: November 2005

We have measured two-dimensional Raman intensity images of laser-recrystallized polycrystalline silicon islands on insulators by a scanning Raman microprobe. It is found that crystallites with about ten µm size grow along the scanning direction of an annealing laser. The crystallographic orientations of the crystallites have been determined by Raman microprobe polarization measurements.
White Light Emitting Thin-Film Electroluminescent Devices with SrS:Ce,Cl/ZnS:Mn Double Phosphor Layers
Authors: Tanaka Shosaku , Mikami Yoshiro , Deguchi Hiroshi , Kobayashi Hiroshi
Published: November 2005

White light emitting thin-film electroluminescent devices have been fabricated. The devices consist of double phosphor layers of a greenish-blue light emitting SrS:Ce, Cl and a yellowish-orange light emitting ZnS:Mn. A brightness level of 1100 cd/m2 at 5 KHz drive has been obtained.
Study of the Phase Transition in BaSm2Mn2O7
Authors: Kamegashira Naoki , Umeno Shigeru
Published: November 2005

The existence of phase transition in BaSm2Mn2O7 was revealed by high temperature X-ray diffractometry to be near 520 K. The phase transition is largely affected by the oxygen nonstoichiometry of this compound. For stoichiometric composition this phase has an orthorhombic distortion due to Jahn-Teller effect of Mn3+ ion and is transformed into a tetragonal phase above the transition temperature. Structure of the high temperature phase is isotypic with that of the oxygen nonstoichiometric phase at room temperature; the latter has a Sr3Ti2O7-type crystal structure with double perovskite bloc.
Anomalous Permeation of Low Energy Neon Atoms in Tungsten at Low Temperatures
Authors: Fukatsu Susumu , Hashizume Tomihiro , Sakai Akira , Sakurai Toshio , Hyodo Shin-ichi
Published: November 2005

Atomic depth profiles of tungsten tips irradiated with neon atoms of low thermal energy [i) 77 K ii) 300 K] were measured with the aid of an atom-probe field ion microscope. The tip temperature was maintained usually at 25 ± K during the course of atom-probe measurements to practically eliminate thermal diffusion. In the case of i), neon atoms were detected at locations as deep as 300 layers from the surface, a depth much greater than that predicted assuming the usual diffusion mechanism. In the case of ii), however, no neon atoms were detected in the matrix. At present no theory seems to have been established to explain such anomalous penetration of low energy neon atoms.
Optimization of Shell Implosion Driven by Black Body Radiation
Authors: Murakami Masakatsu , Nishihara Katsunobu
Published: November 2005

We have studied a spherical ablative shell implosion under an assumption of a constant mass ablation rate. It is found that implosion dynamics is determined only by one parameter. The theory is applied to a shell implosion driven by a steady black body radiation and compared with computer simulations. We have estimated scaling laws of optimum aspect ratio and shell radius on the radiation intensity I
R, which lead to the maximum hydrodynamic efficiency, as R
0/ΔR∝I
R
-1/2 and R
0∝R
I
1/6.
MOCVD Growth of GaAs0.6P0.4 on Si Substrate
Authors: Takeyasu Masanari , Soga Tetsuo , Sakai Shiro , Umeno Masayoshi
Published: November 2005

Single crystalline GaAs0.6P0.4 is grown on (100)2° off Si substrate by metalorganic chemical vapor deposition with the intermediate layers of GaP, (GaP/GaAsP) superlattice and (GaAsP/GaAs) superlattice. PL intensity of GaAs0.6P0.4/Si is about 40% of commercially available GaAs0.6P0.4 grown on GaAs substrate by VPE. Very smooth mirror-like surface is obtained and no crosshatch pattern such as is seen on GaAs0.6P0.4 on GaAs is observed on GaAs0.6P0.4/Si surface.
Enhancement of Gamma-Ray Tolerance in Forward-Biased AlGaAs and GaInAsP Light-Emitting Diodes
Authors: Takagi Toru
Published: November 2005

Bias dependence of light output degradation cuased by gamma-ray irradiation has been investigated for AlGaAs and GaInAsP LEDs. When the device is forward-biased during irradiation, the light output degradation is reduced for both AlGaAs and GaInAsP LEDs. Isochronal and current annealings carried out after exposure to a gamma-ray dose of 108 rad(Si) reveal that this reduction in degradation is attributable to annealing enhanced by carrier injection.
Photo-CVD of Tantalum Oxide Film from Pentamethoxy Tantalum for VLSI Dynamic Memories
Authors: Yamagishi Koji , Tarui Yasuo
Published: November 2005

Recent VLSI requires materials with high dielectric constant in order to reduce their storage capacitor areas. We attempted to form a tantalum oxide film from Ta(OCH3)5 at a low temperature by photo-CVD method. Our evaluation shows that the photo-CVD film obtained in this study has good step coverage, high dielectric constant (20–24), and low leakage current, and is superior to the thermal-CVD film in various characteristics.
Ultra-Thin Amorphous-Silicon Transistors Fabricated by Two-Step Deposition Method
Authors: Katoh Yuukoh , Sugiura Osamu , Takeuchi Yuusuke , Matsumura Masakiyo
Published: November 2005

Ultra-thin amorphous-silicon field-effect transistors have been fabricated using a novel two-step deposition method. Effects of the first active layer on transistor performances have been systematically investigated. Field-effect mobility of the 15 nm-thick transistor fabricated by the two-step deposition method was drastically improved in comparison with that by the conventional single-step deposition method. Operation of a 5 nm-thick transistor has also been described.
Correlation between Infrared-Light Scattering and Absorption Images in an In-Doped LEC GaAs Crystal
Authors: Ogawa Tomoya
Published: November 2005

Infrared light scattering tomography combined with infrared absorption imaging is developed for characterization of semi-insulating GaAs crystals to take simultaneously both the IR absorption and light scattering images.
Very close correlation of many dislocation lines and point defects was found between these images in a semi-insulating In-doped LEC GaAs crystal grown from a stoichiometric melt, while a few dislocation lines showed only light scattering of 1.15 µm laser beam.
A Common Energy Reference for DX Centers and EL2 Levels in III–V Compound Semiconductors
Authors: Hasegawa Hideki , Ohno Hideo
Published: November 2005

The lack of energy reference level for deep levels, which has been one of the major difficulties in previous deep level research, is overcome by Hasegawa-Ohno's hybrid orbital energy level, EHOrecently found for insulator-semiconductor and metal-semiconductor interfaces. EHOis shown to serve as the energy reference for DX centers and EL2 donors in the major III-V compound semiconductors and their alloys. Based on the novel alignment of DX centers with respect to EHOa proposal is made that the DX center is related to the anti-bonding state formed by the substitutional donor impurity atom itself.
Light-Induced Effects in a-Si:H Studied by ESR and Electrical Measurements
Authors: Kumeda Minoru , Uno Mitsuhiro , Morimoto Akiharu , Shimizu Tatsuo
Published: November 2005

Changes in photoconductivity and dangling bond density with strong illumination are measured for a-Si:H films prepared by magnetron sputtering and glow discharge decomposition. The change in the photoconductivity with illumination time and the change in the light intensity dependence of the photoconductivity depend largely on the sample preparation condition. The results are explained in relation to the Fermi level position of the sample.
Surface Reconstruction on a Clean Si(110) Surface Observed by RHEED
Authors: Yamamoto Youiti , Ino Shozo , Ichikawa Toshihiro
Published: November 2005

A “16-structure" was found from careful surface cleaning manners and RHEED observations to be only a superstructure appearing on a clean Si(110) surface. The present work also confirmed clearly that almost all surface structures reported previously were superstructures characteristic of Ni-contaminated Si(110) surfaces.
Growth of ZnSe Films on InxGa1-xAs Substrate by Metalorganic Vapor Phase Epitaxy
Authors: Shibata Noriyoshi , Zembutsu Sakae , Miyashita Tadashi
Published: November 2005

This letter discusses ZnSe epitaxial layers grown on lattice-matched In
x
Ga1-x
As (x=0.032) substrates by metalorganic vapor phase epitaxy. These films emit a stronger near-bandedge photoluminescence at room temperature than ZnSe layers on GaAs substrates do when the film thickness is less than 1 µn. However, self-activated emission intensity, which has been reduced remarkably by decreasing the impurities piled up near the substrate surface, is independent of the lattice parameter of the substrate.
Correlation between the Location of the Interface State Minimum at Insulator-Semiconductor Interfaces and Schottky Barrier Heights
Authors: Ohno Hideo , Hasegawa Hideki
Published: November 2005

Correlation between the energy location of the minimum density of the interface states in insulator-semiconductor systems and the location of the Fermi level pinning in metal-semiconductor systems is reported. The correlation extends over the major III-V semiconductors, which can be explained by the surface disorder model. The unified defect model is not capable of explaining the present correlation.
Photoluminescence Studies on Semi-Insulating In-Doped Dislocation-Free GaAs Grown by LEC Method
Authors: Noto Nobuhiko , Kitagawa Yutaka , Takahashi Tohru , Takenaka Takao
Published: November 2005

Photoluminescence studies were performed at 4.2 K for In-doped dislocation-free GaAs. Large inhomogeneity of carbon-related PL intensity was observed along axial growth direction in an as-grown ingot. It was revealed that the PL intensity was strongly affected by thermal history to which it was subjected during crystal growth. After wafer or ingot annealing, the PL intensity increased and the inhomogeneity was imporved significantly. These observations cannot be explained only by concentrations of carbon and deep donor EL2. Consequently, the PL intensity depends mainly on nonradiative recombination centers and less on EL2.
Electromigration of In Ultrathin Film on Si(111)
Authors: Yasunaga Hitoshi , Kubo Yasunori , Okuyama Naoki
Published: November 2005

The electromigration of a pad of In ultrathin film with a thickness of several monolayers on a Si(111) 7×7 surface was investigated by scanning Auger electron spectroscopy. Indium atoms moved to the cathode in the ultrathin film contrary to conventional electromigration in bulk materials and in thin films and had a mobility of 8.5×10-5 cm2/(V·s) at 80°C. This is three orders of magnitude greater than the mobility of ordinary films. The morphology of the ultrathin film in the process of the movement was studied particularly carefully and proved to be associated with the growth mode of the In film on Si(111).
Oxidation of Si by Microwave-Excited Oxygen-Plasma through Protective Al Coating
Authors: Matsuda Tetsuro , Niu Hirohiko , Maeda Muneo , Takai Munezo
Published: November 2005

An Al film was formed as a protective layer on a Si wafer. Oxidizing species generated in a microwave-excited oxygen-plasma penetrated the Al protective layer under a UV-light irradiation. The depth profile of the chemical composition of the oxidized film was measured by XPS with Ar-ion sputtering. It was found that the UV-light enhances the oxidation rate through a surface excitation. In O2+N2 mixture plasma, intermixed-insulator films on Si (SiO2-Al2O3-SiO2-Si substrate) were prepared by one sequential plasma process. In O2+H2 mixture plasma, the inner SiO2 layer was not recognized.
Selectively Doped n-GaInP/GaAs Heterostructures Grown by MOCVD
Authors: Tone Kiyoshi , Nakayama Takao , Iechi Hiroyuki , Ohtsu Kazuyoshi , Kukimoto Hiroshi
Published: November 2005

We report the first growth of selectively doped n-GaInP/GaAs heterostructures by low pressure metalorganic chemical vapor deposition (MOCVD) using trimethylindium, triethylgallium, phosphine and arsine as source materials. The Shubnikov-de Haas oscillation and the temperature dependence of electron mobility indicate that a two-dimensional electron gas is present at the GaInP/GaAs interface. It is noted that the persistent photoconductivity observed in these heterostructures was very weak. These results suggest potential application of this material system to high electron mobility transistors (HEMT).
BH InGaAsP Lasers with an LPE Grown Semi-Insulating Layer
Authors: Shi S. L. , Yu P. K. L.
Published: November 2005

DCPBH lasers with LPE grown cobalt-doped semi-insulating InP layer for lateral current confinement are described. The lasers with this cobalt-InP layer have higher external quantum efficiencies than the ones without. Low threshold current lasers (15–35 mA) are obtained for active region width of 2–3 µm.
Performance of the TOPAZ Thin Superconducting Solenoid Wound with Internal Winding Method
Authors: Yamamoto Akira , Kichimi Hiromichi , Kimura Nobuhiro , Inoue Hitoshi , Yamaoka Hiroshi , Haruyama Tomiyoshi , Mito Toshiyuki , Araoka Osamu , Tadano Mikito , Suzuki Shoji , Kondo Yoshinari , Kawai Masanori , Doi Yoshikuni , Hirabayashi Hiromi
Published: November 2005

A large thin wall superconducting solenoid magnet was constructed as a major component of the high energy particle detector “TOPAZ” for the TRISTAN e+e- collider at KEK. A newly developed “internal winding method” was an essential technique to fabricate a large coil as thin as possible. The magnet has been successfully tested with iron return yoke. It has been cooled down to 4.5 K and excited up to the rated current of 3650 A with a magnetic field of 1.21 T. Results of the tests and preliminary analyses are reported.
Intermediate Structure at the Ferro-to-Paraelectric Phase Transition of VDF/TrFE Copolymer (54/46 mol%)
Authors: Horiuchi Toshihisa , Matsushige Kazumi , Takemura Tetuo
Published: November 2005

Precise X-ray diffraction measurements for a VDF/TrFE copolymer (54/46 mol%) have been conducted. The computer profile analysis suggests that the crystal structure at room temperature is a mixed one of ferroelectric and paraelectric structures, with increasing temperature the transition from a ferroelectric structure to a paraelectric one occurs passing through an intermediate structure in the ferroelectric phase transition region. This three-component model explains well the temperature variation of the specific volume observed for a bulk specimen.
Preparation of Elevated NA Fluoride Optical Fibers
Authors: Kanamori Terutoshi , Sakaguchi Shigeki
Published: November 2005

Elevated NA fluoride optical fibers having minimum losses of less than 1 dB/km have been prepared using a dry processing technique. NA ranging from 0.19 to 0.24 has been obtained by substituting LiF and/or ZrF4 in basic core and cladding glasses consisting of ZrF4–BaF2–LaF3–YF3–AlF3–LiF by NaF and/or HfF4, respectively. It has been demonstrated by measuring critical cooling rates for glass-formation that glasses containing NaF applied to elevated NA fibers have high glass-forming ability, It is found that elevating NA enables low OH impurity absorption to be successfully reproduced in FEP coated fibers and that applying glasses containing NaF to elevated NA fibers effectively reduces extrinsic scattering.
Secondary Defects in 2 MeV Phosphorus Implanted Silicon
Authors: Tamura Masao , Natsuaki Nobuyoshi
Published: November 2005

Annealing behavior of secondary defects in 2 MeV phosphorus ion implanted (100) silicon has been investigated through cross-sectional and plan-view TEM observation at doses of 2×1013 1×1014 and 5×1014 ions/cm2. The critical dose for generating secondary defects is between 2×1013 and 1×1014 ions/cm2. The maximum defect density is located at a mean depth of 2.1 µm from the surface, a location is deeper than that of the projected range of phosphorus ions and the primary defect peak. This defect position in the crystal is constant under all annealing conditions (e.g., a temperature range of between 750 and 1100°C, annealing time of up to 6780 min at 1000°C), although the vertical distribution width of defects changes with both annealing temperature and time.
Development of ac Calorimetric Method for Thermal Diffusivity Measurement I. Contribution of Thermocouple Attachment in a Thin Sample
Authors: Hatta Ichiro , Kato Ryozo , Maesono Akikazu
Published: November 2005

In a very thin sample, the contribution of addenda, thermocouple, glue etc., to the precise measurement is considered especially in two typical cases, in which the thermocouple is attached to the sample surface using glue. In the one case, glue is painted over the whole one-sided region starting from the thermocouple on the surface and in the other, a small amount of glue is used to fix the thermocouple at a particular point on the surface. Consistent with the theoretical consideration, it is experimentally verified in both cases that the addenda do not affect determination of the thermal diffusivity.
A New Self-Aligned Structure for (GaAl)As High Power Lasers with Selectively Grown Light Absorbing GaAs Layers Fabricated by MOCVD
Authors: Nakatsuka Shin-ichi , Ono Yuuichi , Kajimura Takashi
Published: November 2005

A new transverse-mode stabilizing self-aligned structure for (GaAl)As laser diodes by metal organic chemical vapor deposition (MOCVD) is developed. This structure is characterized by an n-GaAs layer grown selectively outside of a mesa stripe using an SiO2 mask. To control the distance between active and n-GaAs layers a highly selective (GaAl)As etching technique by boiled HCl is used. Furthermore, the laser diodes can operate in the fundamental transverse-mode at light output power up to 70 mW with a threshold current of 60 mA under CW operation at lasing wavelengths of 750–760 nm.
Maskless Etching of AN Using Focused Ion Beam
Authors: Ochiai Yukinori , Shihoyama Kazuhiko , Shiokawa Takao , Toyoda Koichi , Masuyama Akio , Gamo Kenji , Namba Susumu
Published: November 2005

Maskless submicron etching of AN has been performed using ion beam assisted etching (IBAE) technique. 35 keV Ga focused ion beam and chlorine gas was used for the etching. Al target was prepared by evaporation on Si substrate. When the pressure of chlorine gas ambient was varied from 0 to 32 mTorr, the etching rate of Al exhibited a maximum value which was 4.3×10-5cm3·mA-1·min-1 at a pressure of 5 mTorr. This value was about 10 times larger than that of physical sputter etching. Chlorine contamination was found to be below detection limit by Auger analysis.
Donor-Related Deep Level in S-Doped Ga0.52In0.48P Grwon by Chloride VPE
Authors: Kitahara Kuninori , Hoshino Masataka , Kodama Kunihiko , Ozeki Masashi
Published: November 2005

A deep level in S-doped Ga0.52In0.48P grown on GaAs by chloride vapor-phase epitaxy was studied by deep-level transient spectroscopy (DLTS). The deep level concentration obtained by DLTS is increased with donor doping intensity as also the case for the obtained by persistent photoconductivity. The energy of this level strongly depends on thermal and optical ionization processes. These properties are the same as those of the DX center. However, the deep level concentration is considerably smaller than that in Al
x
Ga1-x
As(0.3<x<0.7), which makes Ga0.52In0.48P favorable for heterostructure electron devices.
Lateral GaAs Photodetector Fabricated by Ga Focused-Jon-Beam Implantation
Authors: Iguchi Hidehiko , Hirayama Yoshiro , Okamoto Hiroshi
Published: November 2005

A photodetector with lateral GaAs n+-π-n+ structure is studied. This structure is fabricated by Ga ion implantation into n+-GaAs epilayer on a semi-insulating GaAs substrate using focused-ion-beam (FIB) technology. This photodetector behaves as a phototransistor in low-bias region and avalanche multiplication appears beyond a breakdown voltage. Multiplication gain of more than 50 and impulse response of less than 200 ps were obtained. These characteristics make this device suitable for application in monolithic optoelectronic circuits.
Artificial Membrane System Prepared by Semiconductor Technology
Authors: Shimoide Kouji , Qingde Zhuang , Moriizumi Toyosaka
Published: November 2005

An excitable artificial membrane system fabricated by semiconductor processes was studied. This system had a single fine pore in the middle of the Si3N4. membrane, and an excitable artificial membrane, the triolein membrane, was formed in this pore. It showed rhythmic and sustained oscillations when it was immersed between aqueous solutions of Nail and KCl. It was found that there were two states of the oscillation period, a long term (>10 min) and a short term (<3 s).
Effect of Silicon Doping Profile on I–V Characteristics of an AlGaAs/GaAs Resonant Tunneling Barrier Structure Grown by MBE
Authors: Muto Shunichi , Inata Tsuguo , Ohnishi Hiroaki , Yokoyama Naoki , Hiyamizu Satoshi
Published: November 2005

The effect of Si doping profile on I–V characteristics of an AlGaAs/GaAs resonant tunneling barrier (RTB) structure was studied by changing the thickness of an undoped GaAs “spacer” layer placed adjacent to the RTB. We found that the peak and the valley current density in the negative differential resistance region at 77 K depends strongly on the thickness of the spacer layer. By using a spacer layer of 50 Å, we achieved a resonant tunneling diode with the highest peak current density of 2×104 A/cm2 with a good peak-to-valley ratio of 3.5 at 77 K.
Annealing Effects on Al and AN-Si Contacts with 3C–SiC
Authors: Daimon Hiroshi , Yamanaka Mitsugu , Sakuma Eiichiro , Misawa Shunji , Yoshida Sadafumi
Published: November 2005

Annealing effects on the current-voltage characteristics of Al and Al–Si contacts with n-type and p-type 3C-SiC films, epitaxially grown on Si by chemical vapor deposition, have been investigated. Al electrodes on n-type 3C-SiC show ohmic characteristics stable up to 400°C, but show distinct rectifying characteristics with annealing at 900°C. To the contrary, Al on p-type 3C-SiC clearly changes from non-ohmic into ohmic with annealing at 900°C. Al–Si alloys, which are usually used as ohmic electrodes for p-type SiC, show same behavior as AN on n-type 3C-SiC. These results suggest the diffused Al atoms to yield a certain p-type layer.
InGaAlAs /InGaAs and InAlAs/InGaAlAs Quantum-Well Structures Grown by MBE Using Pulsed Molecular Beam Method
Authors: Fujii Toshio , Nakata Yoshiaki , Muto Shunichi , Hiyamizu Satoshi
Published: November 2005

High-quality In0.52(Ga0.5Al0.5)0.48As/In0.52Ga0.48As (In0.52Al0.48As) multi-quantum-well (MQW) structures with ternary Inlays welts (quaternary InGaAlAs welts) lattice-matched to InP, were grown by MBE using the pulsed molecular beam method. Very narrow full width at half maximums (FWHMs) of photoluminescence spectra (4.2 K) of 10.8 mcV to 5.7 meV for 15-Å-to 100-Å-thick-InGaAs welts were obtained. These values are the narrowest FWHMs ever reported for MQW structures with quaternary InGaAlAs.
Influence of Substrate Temperature on Magnetic Properties and Domains of Amorphous Tb31Fe69 Films
Authors: Takeno Yukio , Suwabe Masatsugu , Sakurai Tomoaki , Goto Kimiyoshi
Published: November 2005

Magnetic properties and domains have been studied for amorphous Tb31Fe69 films prepared by flash evaporation with substrate temperatures T
sub=77 K, 300 K and 473 K. With the increase of T
sub, the perpendicular uniaxial anisotropy conslant of 106 erg/cm3 order increases rapidly from negative to positive. From domain observations on films having positive perpendicular anisotropy, it is found that in film with T
sub=300 K the reversal of magnetization takes place by the rotation of magnetization without domain wall displacement, while when T
sub=473 K the reversal proceeds by nucleation and growth of narrow reverse domains.
Photoconduction of Poly (p-phenylenevinylene) Films
Authors: Tokito Shizuo , Tsutsui Tetsuo , Tanaka Ryuichi , Saito Shogo
Published: November 2005

Large photoconduction in PPV films prepared via sulfonium salt process was found. The photocurrent was proportional to 0.5–0.7th power of the intensity of incident light. This suggested that recombination of photo-generated carriers played an important role in the photoconduction in PPV films. Photocurrent spectrum showed a huge broad peakin a near infrared region at which optical absorption was very weak.
Structural Inhomogeneily in Ge-Doped Silica Core of Optical Fibers Made by the VAD Method
Authors: Nagasawa Kaya , Ohki Yoshimichi
Published: November 2005

Surface of a Ge-doped silica core of optical fibers etched by chloric acid was investigated under a scanning electron microscope. The core made by the VAD method has an inhomogeneity of 20∼100 nm, which is not seen in the core made by the CVD method. Preservation of the structure of fine glass particles where SiO2–GeO2 mixture surrounds SiO2 is considered to cause the inhomogeneity.
Low Noise Oscillator Stabilized by Mechanically Modulated Cavity
Authors: Ohashi Masatake , Tsubono Kimio , Hirakawa Hiromasa
Published: November 2005

A 9.5-GHz oscillator stabilized by a mechanically modulated superconducting cavity has been developed. The vibration of a bar which makes a part of the cavity wall modulates its resonant frequency. The modulation is utilized to detect frequency offset between the cavity and the oscillator. Phase noise reduction in the oscillator of more than 40 db, at 1.5 kHz apart from the carrier, was attained. This type of low phase noise oscillator is useful for a high sensitive parametric vibration transducer of gravitational radiation detectors.
Two-Dimensional Patterson Synthesis of Al–Mn Quasicrystal by Optical Method
Authors: Saito Yahachi
Published: November 2005

The Patterson functions of Al–Mn quasicrystal are derived by optical transformation. The τ3 scaling is found in the Patterson map projected along a 2-fold symmetry axis. Comparison with golden rhombohedra constructing a three-dimensional Penrose tiling leads to the value 4.66±0.10 Å for the edge length of the rhombohedra. Several atomic structure models are discussed in comparison with the results.
Properties of Photoluminescence from ZnTe–ZnSe Superlattices
Authors: Kuwabara Hiroshi , Fujiyasu Hiroshi , Aoki Masaki , Yamada Shoji
Published: November 2005

Excitation spectra and temperature dependence measurements of the photoluminescence(PL) were carried out for the various kinds of the ZnTe–ZnSe superlattices (SLs) prepared by hot wall epitaxy. First observation of strong absorption band by about 0.2 eV above the PL emission band and observed activation energy (0.2 eV) of the thermal quenching which are independent of the SL structures suggest that the PL is related to the radiative recombinations between band edge and localized centers, i.e. Free-to-Bound transitions.
Preparation of Phenylacetylene Polymer Thin Films by Photochemical Polymerization
Authors: Inoue Masumi , Takai Yoshiaki , Mizutani Teruyoshi , Ieda Masayuki
Published: November 2005

Polymer thin films were prepared by photochemical polymerization of phenylacetylene and the chemical structure was investigated. Photochemically polymerized phenylacetylene has few structural defects such as triple bonds left unreacted and is soluble in organic solvents. Its π-electron delocalization is a little more widely extended than that of plasma-polymerized phenylacetylene (P-PPA), indicating that the structure of photochemically polymerized phenylacetylene is much closer to that of polyphenylacetylene synthesized by conventional chemical method.
Critical Current Density of Superconducting Pb–Bi Alloys with Normal Bi Precipitates in a Longitudinal Magnetic Field
Authors: Matsushita Teruo , Miyamoto Yoshihiro , Kikitsu Akira , Yamafuji Kaoru
Published: November 2005

Critical current density was measured for superconducting Pb–Bi stabs with normal Bi precipitates in a longitudinal magnetic field. It was found that the critical current density is proportional to N
p
f
p
d
p, where N
p is the concentration of Bi precipmtates, d
p is their mean spacing and f
p is the elementary pinning force of an interface of Bi precipitate and the superconducting matrix. This result supports the hypothesis that the critical current density in the longitudinal field geometry is determined by the balance between the driving torque and the restraining moment of the pinning forces.
Characteristics of Rechargeable Battery Using Conducting Poly(p-phenylene) Film
Authors: Satoh Masaharu , Tabata Munehiro , Kaneto Keiichi , Yoshino Katsumi
Published: November 2005

A secondary battery utilizing electrochemically prepared poly(p-phenylene) film as cathode material in an electrolyte of LiAsF6/propylenecarbonate with Li anode was studied. A high cell voltage of 4.1 V and energy density of 300 Wh/kg (based on the weight of electroactive materials) were obtained. The cell demonstrates excellent discharge characteristics under the extremely large discharge rate of 2.5 kA/kg with an energy efficiency of more than 85%.
Highly Conductive and Transparent Silicon Doped Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering
Authors: Minami Tadatsugu , Sato Hirotoshi , Nanto Hidehito , Takata Shinzo
Published: November 2005

Highly conductive and transparent films of Si-doped ZnO have been prepared by rf magnetron sputtering of a ZnO target with SiO2 or SiO dopant added. Films with resistivity as low as 3.8×10-4 Ω cm and average transmittance above 85% in the visible region can be produced on low temperture substrates at below 250°C. Great improvement in the stability of the resistivity for use at high temperatures was obtained for Si-doped ZnO films in comparison with undoped films.
Si(001)-2×1 Single-Domain Structure Obtained by High Temperature Annealing
Authors: Sakamoto Tsunenori , Hashiguchi Gen
Published: November 2005

Si(001)-2×1 single-domain structure has been observed by reflection high-energy electron diffraction (RHEED) after a substrate annealing at a temperature of 1000°C for 20 min. This implies surface steps have been changed from monatomic layer to biatomic layer height by the annealing. It was found that the single-domain 2×1 surface structure is a necessary condition to observe stable RHEED intensity oscillations on the Si(001) surface during the growth.
Investigation of Defects in High-Resistivity Undoped CdTe Using the EBIC Method
Authors: Wada Morio , Suzuki Junichi , Hosomatsu Haruo
Published: November 2005

The Electron Beam Induced Current (EBIC) method using an aluminum Schottky barrier was applied to high-resistivity undoped CdTe crystals to obtain images of crystal defects. The defects such as cellular dislocation structures and twins were observed to produce distributions of dark spots in EBIC images. When the crystals were etched with PBr etchant, it was found that the etched patterns corresponded to high intensity regions in the EBIC images.
Fabrication of Index-Guided AlGaAs MQW Lasers by Selective Disordering Using Be Focused Ion Beam Implantation
Authors: Ishida Koji , Takamori Takeshi , Matsui Kazunori , Fukunaga Toshiaki , Morita Tetsuo , Miyauchi Eizo , Hashimoto Hisao , Nakashima Hisao
Published: November 2005

AlGaAs multiquantum well (MQW) lasers with buried optical guide (BOG) were fabricated using Be focused ion beam (FIB) implantation. The process is based on the effect wherein the compositional disordering of Si doped MQW is suppressed by Be ion implantation and subsequent annealing. The proposed process is very simple and does not require any lithographic procedure. It is confirmed that the fabricated laser acts as an index-guided laser. This technique is a promising new step toward optoelectronic integrated circuits.
Elementary Pinning Force of Grain Boundaries in Supereonducting V3Ga Tapes
Authors: Matsushita Teruo , Kikitsu Akira , Sakata Haruhisa , Yamafuji Kaoru , Nagata Masayuki
Published: November 2005

The elementary pinning force of grain boundaries was estimated for superconducting V3Ga tapes prepared by the surface diffusion method on pure and zirconium-doped vanadium tapes. It is 1.6-3.7×10-4 N/m for pure vanadium tapes and 3.8-6.2×10-4 N/m for zirconium-doped tapes. These values are much larger than the theoretical values by Zerweck, by Yetter et al. and by Welch based on the electron-scattering mechanism. Although Thuneberg's theory givesa value comparable to the observed results, it is incompatible with the observed increase in the elementary pinning force with the addition of zirconium.
Characterization of Photo-CVD a-Si:H Films by Thin-Film Transistor Structure
Authors: Suzuki Kazuhiko , Yukawa Yohsuke , Takao Hiroaki , Kuroiwa Koichi , Tarui Yasuo
Published: November 2005

To investigate the dependence of transport properties of photo-CVD a-Si:H on deposition temperature, field effect mobility (µFE) and threshold voltage (V
th) of thin film transistor (TFT) fabricated on a-Si:H prepared at different substrate temperatures were measured. Both µFE and V
th and corresponding photoluminescence (PL) intensity show an optimum value at the deposition temperature of 200°C.