bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Y-Ba-Cu-O Superconducting Films on Cu Substrates by an Electrophoretic Deposition Technique
Authors: Nojima Hideo , Nagata Masaya , Shintaku Hidetaka , Koba Masayoshi
Published: February 2005

Direct formation of Y1Ba2Cu3O7-x
films on Cu substrates by electrophoretic deposition is studied, Electrophoretic deposition was carried out using presintered Y1Ba2Cu3O7-x
powder dispersed in distilled acetone. The deposited films were annealed in air at 900°C. We succeeded in obtaining superconducting Y1Ba2Cu3O7-x
films on Cu substrates. The films on Cu plates and Cu film/YSZ exhibited the zero-resistance state at 66 K and 76 K, respectively. Interfacial chemical reactions at the Y1Ba2Cu3O7-x
/Cu interface are discussed. The achievement of the zero-resistance state is considered to be due to the reduction of the interfacial reactions.
Minority Carrier Lifetime Measurement in HF Solution to Evaluate Si Substrates for Solar Cells
Authors: Nammori Takayuki , Okamoto Koji , Nunoi Tohru , Hayashi Yutaka
Published: February 2005

Minority carrier lifetime measurement using a microwave photoconductivity decay method was examined. A simple method of immersing a silicon wafer in a toxic HF solution by using a plastic envelope is introduced. An effective lifetime in 50% HF solution is much higher than that in air due to reduction of the surface recombination velocity and is almost the same compared with that of an oxidized and well-passivated substrate. This method provides the effective lifetime, which approximates a bulk lifetime, without an oxide layer and is useful in estimating the short circuit current of solar cells prior to the cell fabrication.
Quantum-Confined Stark Effect in Stepped-Potential Quantum Wells
Authors: Morita Masahiko , Goto Katsuyuki , Suzuki Takeo
Published: February 2005

A multi-quantum well pin diode which contains quantum wells where the band gap changes in a steplike manner along the growth direction has been grown by molecular beam epitaxy. The quantum-confined Stark effect has been observed by photocurrent spectroscopy at room temperature, and a larger red shift of the lowest exciton absorption peak in comparison with the conventional rectangular-shaped quantum well has been observed under a considerably large amount of applied electric field.
Novel Window-Structure AlGaInP Visible-Light Laser Diodes with Non-Absorbing Facets Fabricated by Utilizing GaInP Natural Superlattice Disordering
Authors: Ueno Yoshiyasu , Fujii Hiroaki , Kobayashi Kenichi , Endo Kenji , Gomyo Akiko , Hara Kunihiro , Kawata Seiji , Yuasa Tonao , Suzuki Tohru
Published: February 2005

Window-structure AlGaInP visible-light ( λL=680 nm) laser diodes (LDs) have been fabricated, for the first time, by utilizing GaInP natural superlattice (NSL) disordering with selective Zn diffusion. The bandgap energy for the active layer near the mirror facets is increased by 70 meV by the NSL disordering. An 80 mW output power in a fundamental transverse-mode has been achieved for the uncoated window LDs under 1 µsec long pulsed operations. The maximum output power density for the window LDs is estimated to be 10 MW/cm2, which is five times higher than that for conventional LDs.
632.7 nm CW Operation (20°C) of AlGaInP Visible Laser Diodes Fabricated on (001) 6° off toward [110] GaAs Substrate
Authors: Kobayashi Kenichi , Ueno Yoshiyasu , Hotta Hitoshi , Gomyo Akiko , Tada Kentaro , Hara Kunihiro , Yuasa Tonao
Published: February 2005

632.7 nm continuous wave operation was achieved at 20°C, by an AlGaInP visible laser diode (LD) with an AlGaInP quaternary active layer fabricated on a (001) GaAs substrate with a misorientation angle of 6° toward the [110] direction. The epitaxial layers for the laser structure are grown by metalorganic vapor phase epitaxy. The lasing wavelength is almost the same as that for He-Ne lasers. Lasing wavelengths for the LDs were also compared with wavelengths for those fabricated on an exact (001) orientation substrate.
Degradation of Performance due to Photoinduced Index Change in a Ti:LiNbO3 Two-Mode Interference Wavelength Division Multi/Demultiplexer
Authors: Byun Young Tae , Kim Sun Ho , Kim Dong Hwan , Choi Sang Sam
Published: February 2005

The effect of photoinduced index change in a Ti:LiNbO3 wavelength division multiplexer, based on the wavelength-dependent two-mode interference, is investigated experimentally at 0.633 µm (pump beam) and 0.82 µm (probe beam) wavelengths. The experimental result shows that the device performance is degraded due to a photoinduced index change. This effect is also calculated numerically by the beam propagation method using the periodic index perturbation inside the waveguide. The calculated result agrees qualitatively with the experimental result.
Effect of Binder Matrices on Charge Transport in Polymers Doped with a Butadiene Derivative
Authors: Aratani Sukekazu , Saito Toshiro , Kawanishi Tsuneaki , Kinjo Noriyuki
Published: February 2005

The effects of polymer matrices on charge transport in polymers doped with a butadiene derivative have been studied. Transient photocurrent shapes in polysulfone and polyestercarbonate are very different from those in polystyrene and polycarbonate. It appears that the low-energy levels of the polymer matrices affect transient current shapes.
Mössbauer Effect of Decagonal and Amorphous Phases in Al-Ni-Fe System
Authors: Tsai An-Pang , Kataoka Noriyuki , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

Decagonal (D) and amorphous phases in an Al-Ni-Fe system have been examined by the Mössbauer effect. The Mössbauer spectrum of the D-phase is similar to that of a rapidly solidified Al-Cu-Fe icosahedral (I-) phase, indicating the similarity of the environmental structure around the Fe atom site between D- and I-phases.
Transmission Electron Diffraction Pattern of Electron-Irradiation-Induced {113}-Faulted Loops in Si
Authors: Takeda Seiji , Muto Shunsuke , Hirata Mitsuji
Published: February 2005

Transmission electron diffraction patterns from {113}-faulted loops in Si, which are introduced by electron irradiation in a high-voltage electron microscope, have been observed for the first time. The diffraction patterns were observed after removing the perfect crystal of Si by ion-thinning. The patterns were taken under the plan-view condition. The patterns were consistently interpreted by assuming a 1×1 unit cell on a {113} plane.
A System for Detecting Metal Atoms Ejected from Solid Surfaces by Means of Multiphoton Resonance Ionization
Authors: Yamada Muneo , Inoue Masahiko , Morita Kenji , Nadahara Sohichi , Watanabe Masaharu
Published: February 2005

A multiphoton resonance ionization system combined with a time-of-flight technique has been developed. It consists of an excimer laser-pumped dye laser, a SHG crystal for generation of the second harmonic radiation and a time-of-flight system for measuring the velocity of photoions. Using this system, the resonance wavelengths for multiphoton ionization of Ni and Fe atoms are determined, and the ionization efficiency for sputtered Ni is demonstrated to be saturated to 100%.
One-Step Growth of GaAs Layers on Si Substrates by Low-Pressure MOCVD
Authors: Sato Kiyotaka , Togura Kenji
Published: February 2005

GaAs epitaxial layers have been successfully obtained on Si(100) <011 > 4°-off substrates by 3∼4 Torr low-pressure MOCVD using TEG and AsH3 at 590∼610°C. This method consists of one-step growth in which the initial buffer layers or intermediate layers were neglected. As-grown 5 µm GaAs layers revealed an etch pit density of 1×106∼5×106/cm2. The FWHM of X-ray diffraction was about 180 arc sec for the (400) reflection of 4.5∼5 µm GaAs layers. Hall mobilities of Si-doped GaAs layers were 3900 cm2·V-1·s-1 with an electron concentration of 1.4×1017/cm3 and 5100 cm2·V-1·s-1 with 1.6×1016/cm3 at room temperature.
Low-Damage GaInAs(P)/InP Nanometer Structure by Low-Pressure ECR-RIBE
Authors: Ravikumar K. G. , Kudo Koji , Arai Shigehisa , Suematsu Yasuharu
Published: February 2005

Low defect nanometer structures of 70 nm ∼25 nm width are formed in GaInAs/GaInAsP/InP multi-quantum-well layers with low ion extraction voltage (20 V) and at low-pressure (LP) of etching gas (5×10-6 Torr) using electron cyclotron resonance reactive ion beam etching (ECR-RIBE) system for the first time. The room temperature photoluminescence peak intensity after etching and slight cleaning, taking into account the remaining volume of the GaInAs/GaInAsP layer, was almost 60% of that before etching, which proved the very low-damage nature of the present etching method. Moreover we also report for the first time the fabrication of multi-layered GaInAs/InP quantum wire (3 periods) structure using LP-ECR-RIBE.
Effect of Reduction in Impurity Content for a-Si:H Films
Authors: Morimoto Akiharu , Matsumoto Minoru , Kumeda Minoru , Shimizu Tatsuo
Published: February 2005

a-Si:H films with various impurity contents were prepared by three kinds of glow discharge decomposition systems. The impurity content for films prepared by these systems was determined by SIMS, and the dark conductivity and the density of charged dangling bonds were also measured. The following results were obtained: the dark conductivity σd, the activation energy E
a and the density of charged dangling bonds are closely correlated with the N and/or O impurity content. These results suggest that the Fermi level and the charged dangling bond density in a-Si:H are largely affected by the presence of the impurity-defect pair such as N4
++Si3
- and/or O3
++Si3
-.
Tunneling Time between Resonantly Coupled Quantum Wells: Measurement and Comparison with h/ΔE
Authors: Shimizu Naofumi , Furuta Tomofumi , Waho Takao , Mizutani Takashi
Published: February 2005

The electron tunneling time between double quantum well structures is investigated by a photoluminescence decay time measurement. In order to compare the measured tunneling time near resonant conditions with the coherent tunneling time h/Δ
E, two samples are examined: one with a thick inner barrier and hence large h/Δ
E, and the other with a thin inner barrier and small h/Δ
E. The measured tunneling times for both samples do not agree with h/Δ
E. This result suggests that the resonant tunneling time derived from the photoluminescence decay time is different in nature from the coherent tunneling time. Possible mechanisms responsible for the measured tunneling time are discussed.
A Soft X-Ray Microscope Using an Imaging Detector
Authors: Inoue Soichi , Ogawa Yoji , Ueda Katsunobu , Sumiya Mitsuo , Takigawa Tadahiro , Aoki Sadao
Published: February 2005

An X-ray microscope, consisting of a Wolter-type mirror and an imaging detector, was constructed. The configuration of the mirror was optimized by the ray-tracing procedure. The resolution of the imaging detector was estimated to be better than 1 µm from the spot diagram of the electron lenses. A photocathode made of a CsI layer as a photoemitter and a SiNx membrane as a support for the CsI layer is presented. The fundamental performance of the X-ray microscope has been evaluated, and its resolution has been estimated to be better than 2 µm.
Characterization of Column III Vacancies in AlxGa1-xAs/GaAs Heterostructures Grown by Molecular Beam Epitaxy through Slow Positrons
Authors: Lee Jong-Lam , Wei Long , Tanigawa Shoichiro , Nakagawa Tadashi , Ohta Kimihiro
Published: February 2005

Several types of selectively doped Al
x
Ga1-x
As/GaAs heterostructures were grown by molecular beam epitaxy, and were characterized by slow positron beams to obtain the depth distribution of vacancy-type defects. The results indicate that GaAs layers grown on Al
x
Ga1-x
As contain a number of Ga vacancies V
Ga in comparison with those grown on GaAs layers. This could be a reason for the low mobility of carriers in an inverted high-electron-mobility transistor because the V
Ga in the channel layer can act as a scattering center for the motion of electrons. It is also observed that the dependence of the creation of V
III, namely V
Ga or V
Al, in Si-doped Al
x
Ga1-x
As on the Si concentration is much weaker than that in Si-doped GaAs.
Coherent Growth of ZnSe Thin Film at Low Growth Temperature by Hydrogen Radical Enhanced Chemical Vapor Deposition
Authors: Gotoh Jun , Kobayashi Tohru , Shirai Hajime , Hanna Jun-ichi , Shimizu Isamu
Published: February 2005

ZnSe thin films were grown epitaxially on (100) GaAs substrates from metalorganic compounds with the aid of atomic hydrogen at low substrate temperature, i.e., 300°C or less. The film of 1 µm or more in thickness was grown coherently at the growth temperature of 230°C. This pseudomorphic structure with the thickness of 0.1 µm was quite stable and did not deform when it was annealed at a temperature of as high as 600°C. The lattice relaxation is strongly correlated with the crystallinity depending on the growth conditions which is a specific feature of this technique that enables the preparation of a stable pseudomorphic structure. The balance between adsorption and desorption of the precursors is considered to be the major factor responsible for the arrangement of atoms in the vicinity of the growth surface at rather low temperature.
Oriented Structure and Superconducting Properties in Dense Y1Ba2Cu3 Oxides Prepared by Press Forging
Authors: Matsuzaki Kunio , Inoue Akishisa , Masumoto Tsuyoshi
Published: February 2005

Dense Y1Ba2Cu3 oxides with a highly oriented structure were prepared by press forging at temperatures above 1248 K in air. The c plane of the oxides is preferentially oriented perpendicular to the pressing direction, and the orientation factor (F) and density attained by press forging at 1273 K are 0.58 and 6.19 Mg/m3, respectively. Subsequent annealing treatment for 36 h at 1173 K and for 200 h at 773 K in O2 for the press forged oxides causes a high-T
c superconductivity with T
c of 90 K and J
c of 800 A/cm2 at 77 K in zero field. The J
c value seems to be attributed to the highly oriented and densified structure.
Nonstoichiometry and Mixed Pr Valency in (Pr1-xSrx)(Pr1-yCey)CuO4-z
Authors: Kito Hijiri , Sawa Hiroshi , Akimitsu Jun , Izumi Fujio , Ishigaki Tōru , Asano Hajime
Published: February 2005

The structural parameters of a nonsuperconductor (Pr0.6Sr0.4)(Pr0.75Ce0.25)CuO4-z
(z=0.012) were refined by the Rietveld analysis of TOF neutron powder diffraction data. It is isomorphous with a superconductor (Nd1-x
Sr
x
)(Nd1-y
Ce
y
)CuO4-z
and consists of K2NiF4- and Nd2CuO4-type units stacked alternately along the c-axis. An apical oxygen site in the K2NiF4 unit is 1.2% deficient. Pr atoms in the Nd2CuO4 unit are, at least partially, in the oxidation state +4. The origin of nonsuperconductivity in this compound is discussed from a crystal chemical point of view.
Single-Crystal Growth of (LaSmSr)2CuO4
Authors: Oka Kunihiko , Unoki Hiromi , Hayashi Kunihiko , Nishihara Yoshikazu , Takeda Yasuo
Published: February 2005

A superconducting crystal of (LaSmSr)2CuO4 with T*-phase structure has been grown by the travelling-solvent floating-zone (TSFZ) method. A phase diagram between La0.8Sm1.0Sr0.2CuO4 and CuO was produced to determine the constituent of the solvent. Single crystals with a maximum size of 3×3×6 mm were obtained, which were annealed in a high-pressure oxygen atmosphere and exhibited superconductivity at about 17 K.
Fine Pattern Formation of Gallium Arsenide by In Situ Electron-Beam Lithography Using an Ultrathin Surface Oxide as a Resist
Authors: Taneya Mototaka , Sugimoto Yoshimasa , Hidaka Hiroshi , Akita Kenzo
Published: February 2005

Formation of fine patterns such as lines and spots on a GaAs surface by in situ electron beam (EB) lithography is demonstrated. An ultrathin surface oxide (<1 nm) of GaAs is used as a resist film, which can be patterned by EB-assisted etching. The minimum pattern size of less than 1.0 µm is obtained; it is limited by the electron beam shape in the present experiment. The EB-induced patterning of the oxide resist is not due to substrate heating or minority carrier generation, but to excitation of the sample surface and/or the chlorine atoms adsorbed on the oxide resist film.
Proposal for Device Transplantation using a Focused Ion Beam
Authors: Ohnishi Tsuyoshi , Kawanami Yoshimi , Ishitani Tohru
Published: February 2005

Device transplantation using a focused ion beam (FIB) has been proposed as a new high-resolution technique for microdevice assembly as well as device repair. FIB sputtering, redeposition, and FIB-induced deposition each work as a cutter or a fixer. Feasibility experiments have been carried out both for dummy-device transplantation on a silicon substrate and for microgear fabrication.
A Ferroelectric Layer in a Cell Containing a Polar Molecular Mixture in Nematic and Isotropic Phases
Authors: Mochizuki Akihiro , Motoyoshi Katsusada , Kobayashi Shunsuke
Published: February 2005

A polarization switching current has been observed in a cell containing highly polarized molecules, which normally takes a nematic phase, with highly polarized orientation films for a triangular-voltage waveform both in the nematic and isotropic phases. The observed polarization current is thought to originate from the switching of the longitudinal dipole moments of the moelcules which form the layers that are made of decomposed liquid crystal monomers adsorbed on the orientation films. The results suggest the existence of a ferro-electric layer in the vicinity of the orientation layers in the cell.
Void Formation and Its Effect on Dopant Diffusion and Carrier Activation in Si-Implanted GaAs
Authors: Chen Samuel , Lee S.-Tong , Braunstein G. , Ko K.-Y. , Zheng L. R. , Tan T. Y.
Published: February 2005

GaAs samples, implanted with 220 keV Si to doses ranging from 3×1013 to 1×1015 cm-2 and annealed at 850°C were studied. Using transmission electron microscopy (TEM), voids were found in samples with implant doses ≥3×1014 cm-2 after an annealing time as short as 5 s. In the same region where voids were found, capacitance-voltage measurements showed abnormaly low electron concentrations. Also in the same region, secondary ion mass spectrometry (SIMS) measurements showed anomalies in the Si concentration profiles and required the interpretation that a Si redistribution process had occurred. At high Si implant doses, the onset of void formation, the abnormaly low electron concentration, and the Si accumulation anomaly are concurrent. Based on these results, we conclude that voids inhibit the Si electrical activity and lead to the Si diffusion anomaly.
Vapor Phase Epitaxial Growth of Highly Conductive P-Type ZnSe Films with Codoping of P and Li
Authors: Muranoi Tetsuo , Fujita Yasuhiro , Watanabe Toshio , Ishii Nobunao , Moto Yoshinori , Furukoshi Mitsuo
Published: February 2005

Highly conductive p-type ZnSe films were grown at 450–500°C onto (100)GaAs by vapor phase epitaxy with codoping of P and Li. Vapors of Zn, Se and impurities were transported separately to the vicinity of the substrates. Hall effect measurement revealed that p-type films were degenerate. When either only P or Li was doped, the resistivity was very high and its conductivity type was unknown. The SIMS analysis showed a uniform profile of both impurities in the p-type epitaxial film: the Li concentration was estimated as 1019 cm-3; P was an order of 1018 cm-3 with the aid of EPMA.
Selectively Doped n-InAlAs/InP Heterostructures Grown by MOCVD
Authors: Fukuhara Junji , Shimizu Saburo , Yamakawa Hiroyuki
Published: February 2005

For obtaining an abrupt interface in InAlAs/InP heterostructure by MOCVD, it is very important to suppress the formation of the transition layer induced by the substitution of group-V atoms at the interface. A new switching valve has been designed for obtaining an abrupt heterointerface. A selectively doped n-InAlAs/InP heterostructure grown using this new valve has exhibited SdH oscillation. The 2DEG mobility has been observed to be as high as 99000 cm2/(V ·s) at 77 K.
Characterisation of Incommensurate Bi2+xSr2-xCuOz by X-Ray Powder Diffraction and Oxygen Content Determinations
Authors: Sinclair D. C. , Irvine J. T. S. , West A. R.
Published: February 2005

The composition-temperature stability region of the solid solution Bi2+x
Sr2-x
CuO
z
, phase R, has been determined. At 800°C, 0.15<x<0.40, and at melting temperatures 0.10<x<0.40. The X-ray powder diffraction pattern can be indexed using a pseudo-tetragonal subcell, a=b=5.390(1), c=24.59 Å, with a supercell vector q
* given by q
*=n δb
*-n
ε
c
*, where δ=0.21, ε=0.55, for x=0.30 and n=1, 2 …. Both a and ε increased with x, c decreased with x and δ was independent of x. The excess oxygen content, α, was determined to be (0.18±0.02) by citrate iodometry and was independent of x. The total oxygen content z, given by z=6+x/2+α, was confirmed to be 6.33±0.04, for x=0.30, by hydrogen reduction thermogravimetry.
Synthesis and Properties of YBa2Cu4O8 Superconductor by Aerosol Flow Reacting Method
Authors: Nishio Kozi , Sakai Takenobu , Ogawa Naoyuki , Yamaguchi Koji , Hirabayashi Izumi , Tanaka Shoji
Published: February 2005

The superconducting phase YBa2Cu4O8 has been synthesized using an aerosol flow reacting method with starting solutions containing stoichiometric compositions of Y/Ba/Cu=1/2/4. The powders obtained were spherical and their diameters were uniformly distributed below 1 µm. The heat treatment was made at about 800°C for 5 h in flowing oxygen. The sintered bodies fabricated from these powders show the onset of superconducting transition at 80 K. Our result shows that the YBa2Cu4O8 phase can be synthesized in a short time in the form of the fine powder using an aerosol flow reacting method.
Quench and Melt Growth Process of Suspension-Spun Y-Ba-Cu-O Superconducting Filament
Authors: Goto Tomoko , Kino Yuzuru
Published: February 2005

A quench and melt growth process was used to enhance the J
c of the suspension-spun Y-Ba-Cu-O filaments. By controlling the melt growth process of the filament, dense and highly oriented textures were produced, and transport J
c of more than 4.5×104 A/cm2 at 77 K, 0 T was achieved.
Dynamic Optical Interconnection in BaTiO3
Authors: Sakamoto Akira
Published: February 2005

A dynamic optical interconnection is demonstrated using self-pumped phase conjugation which is automatically built up in a BaTiO3 crystal. The connection is reconfigurable according to positions, intensities and modulations of incident beams. Although the response to establish the connection is relatively slow, phase-conjugate outputs respond to rapid modulation once the connection has been made.
Designing a Binary Fourier-Phase-Only Correlation Filter Using a Simulated Annealing Algorithm
Authors: Nomura Takanori , Nagase Takamitsu , Itoh Kazuyoshi , Ichioka Yoshiki
Published: February 2005

A method of designing a multiple-object recognition filter using a simulated annealing algorithm is presented. This filter has only binary phase information and is correlated with a binary Fourier-phase component of a test object. The filter is used in an incoherent-optical/digital-electric hybrid system. Computer simulations confirm the superior performance of this filter.
MBE Growth Method for Pyramid-Shaped GaAs Micro Crystals on ZnSe(001) Surface Using Ga Droplets
Authors: Chikyow Toyohiro , Koguchi Nobuyuki
Published: February 2005

Micro crystals of GaAs which were pyramid-shaped and 35 nm in bottom length were grown epitaxially on a ZnSe(001) surface by using As-incorporated growth into Ga droplets for the first time. These micro crystals consisted of (111) facets. The size distribution was controlled within 16% in deviation. The As-incorporated lateral growth of GaAs was not observed. A newly proposed method was thought to be useful in fabricating quantum well boxes.
Super Large Grain Polycrystalline Silicon Obtained from Pyrolysis of Si2H6 and Annealing
Authors: Scheid Emmanuel , Mauduit Bernadette De , Taurines Philippe , Bielle-Daspet Danielle
Published: February 2005

Polycrystalline silicon films on SiO2 are formed by Low Pressure Chemical Vapor Deposition from disilane at 450°C and subsequent annealing at 600°C. Homogeneity performances of the deposition are given, which compares with those of Si deposition from SiH4. The structure of the polysilicon material obtained after annealing is shown. The resulting grain size is much larger than the one that could be obtained by Si deposition from SiH4 and annealing. An optical evaluation of the film is given, confirming the potential of Si2H6 for the fabrication of high field effect mobility thin film transistors.
Improvement of Oxide Leakage Currents in MOS Structures by Postirradiation Annealing
Authors: Lin Jing-Jenn , Hwu Jenn-Gwo
Published: February 2005

Postirradiation annealing was used to efficiently reduce the oxide leakage currents in MOS structures after sample preparation. Generally, it is found that leakage currents exist more or less in oxide no matter how the oxidation process changes. However, when a sample receives an irradiation of 60Co with a total dose of 106 rads (SiO2) and an anneal in N2 at 400°C for 10 minutes successively, its high-frequency and quasi-static capacitance-voltage (C-V) curves are nearly coincident in the accumulation region. It is shown that in each postirradiation annealing, the irradiation improves the oxide leakage current while the anneal recovers the radiation-induced damage. Both the bulk oxide leakage current and the surface leakage current are suitably improved after postirradiation annealing.
Ion Beam Collider for Fusion Using Ion-Beams Trapped in a Radial Potential Well
Authors: Mohri Akihiro , Yuyama Tetsumori , Michishita Toshinori , Tanaka Hitoshi
Published: February 2005

A new method for D-3He fusion is proposed. To generate the fusion reaction, counterstreaming energetic ions are produced and trapped in the radial effective potential well which is formed by a radial electric field and an axial magnetic field. Deformation of the magnetic field due to diamagnetic currents increases the counteraction of the motion. Study of the local power balance by a 2D-Fokker-Planck code shows that a net fusion output is obtainable at an electron energy confinement time in a probably accessible range.
Growth of GaAs by Cold-Wall Metalorganic-Chloride Vapor Phase Epitaxy
Authors: Ikeda Hitoshi , Kamisawa Masaru , Koukitu Akinori , Seki Hisashi
Published: February 2005

This report describes the first successful growth of GaAs by metalorganic-chloride vapor phase epitaxy in a cold-wall-type reactor. Triethylgallium was adopted as the group III source material, and AsCl3 instead of fatally toxic AsH3 was used as the arsenic source. Growth rates of about 10 µm/h with mirror like surfaces were obtained at the growth temperature of 650°C. The growth rate study on this system showed that mass transport was the rate-determining step in the overall process.
An SCR with Simple MIS Structure
Authors: Chang D. C. Y. , Lee C. L. , Lei T. F.
Published: February 2005

A device to work as an SCR with a simple MIS p-n Structure is proposed and demonstrated. It employs two junction diodes, with a thin oxide layer grown prior to metallization. This device can act as a triac when a bi-directional ac voltage is applied, while acts as an SCR when a bias voltage is applied to the N-substrate.
Crystal Orientation of YBa2Cu3O7-y Thin Films Prepared by RF Sputtering
Authors: Arikawa Tadashi , Itozaki Hideo , Harada Keizo , Higaki Kenjiro , Tanaka Saburo , Yazu Shuji
Published: February 2005

The effect of growth temperature on the crystallinity and morphology of YBa2Cu3O7-y
thin films was investigated. Thin films were grown on MgO (100) single-crystal substrates by RF magnetron sputtering. Preferred orientations of thin films can be controlled by adjusting the substrate temperature, T
s; (100) a-axis oriented films were deposited at 540°C<T
s<550°C, (110) oriented films were deposited at 565°C<T
s<600°C and (001) c-axis oriented films were deposited above 610°C.
Current-Voltage Characteristics of YBa2Cu3Oy/La0.7Ca0.3MnOz/YBa2Cu3Oy Trilayered-Type Junctions
Authors: Kasai Masahiro , Ohno Toshiyuki , Kanke Yoko , Kozono Yuzoo , Hanazono Masanobu , Sugita Yutaka
Published: February 2005

YBa2Cu3O
y
(superconductor)/La0.7Ca0.3MnO
z
(magnetic material)/YBa2Cu3O
y
(superconductor) trilayered-type junctions were prepared on MgO(100) single-crystal substrates, and the current-voltage characteristics were examined. The top and bottom YBa2Cu3O
y
layers were 200 nm thick, and the La0.7Ca0.3MnO
z
layer was 20, 30, 50 or 100 nm thick. A supercurrent was observed through all the La0.7Ca0.3MnO
z
layers, even the thickest one. Further investigation showed that a supercurrent could he observed through the 500-nm barrier layer.
Low Threshold Current and High Relaxation Oscillation Frequency of Short-Cavity Integrable InP/InGaAsP BRS Laser
Authors: Bouadma Nordine , Sermage Bernard , Devoldere Pascal
Published: February 2005

We describe the fabrication and modulation characteristics of short cavity InP/InGaAsP buried ridge stripe (BRS) lasers with ion beam etched facets. A CW threshold current as low as 9 mA is achieved for 50 µm-long cavity laser. A relaxation oscillation frequency in excess of 17 GHz is observed in such laser for an output optical power of only 9 mW/facet. The small signal -3 dB modulation frequency of such device is 11.5 GHz and is limited by the parasitic impedances of the BRS structure.
Temperature Dependence of the Half-Wave Voltage in Ti:LiNbO3 Waveguide Devices at 0.83 µm
Authors: Fujiwara Takumi , Kawazoe Takemi , Mori Hiroshi
Published: February 2005

We report on experimental results of the temperature dependence of the refractive index change induced by an electric field in Ti-diffused LiNbO3 waveguide phase modulators for a wavelength of 0.83 µm in the temperature range from 0°C to 105°C.
Effect of Electron and Neutron Irradiation on the Cathodoluminescence of Nitrogen-Doped CVD Diamond
Authors: Yokota Yoshihiro , Kawarada Hiroshi , Hiraki Akio
Published: February 2005

The effect of 20 MeV electron and neutron irradiation on the cathodoluminescence (CL) spectra of nitrogen-doped CVD diamond has been investigated. The center called 5RL and the center with a zero-phonon line at 3.19 eV (389 nm) are induced by irradiation alone. The center with a zero-phonon line at 2.16 eV (575 nm) has been formed by annealing at 900°C subsequent to the irradiation. The distributions of these centers have been revealed by CL imaging.
Tilted Homeotropic Alignment of Liquid-Crystal Molecules Using the Rubbing Method
Authors: Seki Hidehiro , Itoh Yasuhisa , Uchida Tatsuo , Masuda Yoichiro
Published: February 2005

It is well known that slightly tilted homeotropic alignment of liquid-crystal molecules is obtained by oblique evaporation followed by homeotropic treatment. However, this method has disadvantages in obtaining large area uniformity and productivity because of the requirement of large vacuum equipment. In this paper, a new alignment technique of slightly tilted homeotropic alignment using the rubbing method (THR method) is proposed, and its applicability to display devices is discussed.
Two Types of Anchoring Structure in Smectic Liquid Crystal Molecules
Authors: Iwakabe Yasushi , Hara Masahiko , Kondo Katumi , Tochigi Kenji , Mukoh Akio , Garito Anthony F. , Sasabe Hiroyuki , Yamada Akira
Published: February 2005

The anchoring structures of smectic liquid crystals, n-alkylcyanobiphenyl (mCB: m=8, 10, 12), on molybdenum disulfide (MoS2) are directly observed by scanning tunneling microscopy (STM) in order to analyze the alignment mechanism of liquid crystals. For 8CB, the anchoring structure is of the periodic monolayer type, while 10CB and 12CB take a bilayer structure in which there is no interdigitation of the cyano groups. These structures on MoS2 depend on the length of the alkyl group in contrast to those on graphite. The mechanism of alignment is discussed based on the STM results.
p+-n+ GaAs Tunnel Junction Diodes Grown by Flow-Rate Modulation Epitaxy
Authors: Makimoto Toshiki , Horikoshi Yoshiji
Published: February 2005

This paper discusses the p+-n+ GaAs tunnel junction diodes grown by flow-rate modulation epitaxy using carbon and silicon as p-type and n-type dopants, respectively. It also investigates the effect of the conditions of p+-n+ junction interfaces on the excess current. While the excess current drastically increases when p+- and n+-layers are overlapped on an atomic scale, it gradually decreases and tends to saturate when the undoped layer thickness inserted at the interface is increased. These results indicate that the p+-n+ junction interfaces grown by flow-rate modulation epitaxy are quite abrupt.
DC-Resistive-Heating-Induced Step Bunching on Vicinal Si (111)
Authors: Homma Yoshikazu , Mcclelland Robert J. , Hibino Hiroki
Published: February 2005

Step bunching on a 1°-misoriented Si (111) surface induced by DC resistive heating is observed by ultrahigh-vacuum scanning electron microscopy. Step band regions of the DC-heating-induced bunching surface break up into finer step bands (subbands) and (111) facets below the (7×7)↔(1×1) phase transition temperature (T
c=830°C). The temperature dependence of bunching-inducing current direction on the vicinal surface is the same as that of nearly flat (111) surfaces previously reported, except that bunching is induced for the opposite current direction to nearly flat (111) surfaces below T
c.
Transport in Novel Gated Quantum Wires: The Impact of Wire Length
Authors: Eugster Cristopher C. , Alamo Jesús A. del , Rooks Michael J.
Published: February 2005

Split-gate quantum wires of various lengths including 0.0 µm (constrictions), 0.5 µm, and 1.0 µm have been fabricated on an AlGaAs/GaAs modulation-doped heterostructure. Confinement is achieved using a split-gate formed by two 40 nm Au/Pd lines, resulting in small gate leakage and short electron-beam writing times. In a two-probe measurement, we have observed strong conductance steps at 4.2 K in 0.5 µm long split-gate quantum wires. These features, which are characteristic of near ballistic electron transport through the wire, are present at temperatures as high as 10 K. Transport through the 0.0 µm constrictions was dominated by tunneling and transport in the 1.0 µm long wires was of a diffusive nature.
Electronic Structure of Polyfuran and Poly(3-alkylfuran)
Authors: Wang Shenglong , Kawai Tsuyoshi , Yoshino Katsumi , Tanaka Kazuyoshi , Yamabe Tokio
Published: February 2005

The electronic structure and optical spectrum of polyfuran and poly(3-hexylfuran) have been studied both experimentally and theoretically. The band gap of poly(3-hexylfuran) is narrower than that of polyfuran. The result is explained based on the theoretical results of the electronic structure of a model polymer.
Three Dimensional Transient Simulation of Complex Silicon Devices
Authors: Conti Paolo , Heiser Gernot , Fichtner Wolfgang
Published: February 2005

We present a general-purpose program for the simulation of semiconductor devices in three dimensions. This program solves the Poisson and continuity equations in steady-state and transient conditions. The implemented grid allocation scheme allows for spatial grid adaption in all directions. The linear systems are solved using preconditioned conjugate gradient-like methods. We describe the investigation of parasitic latchup in a CMOS structure and of the turn-off of a bipolar transistor with our program. Transient simulations on meshes with several tens of thousands of points can be performed within hours on a supercomputer.
Coupling of Monte Carlo and Drift Diffusion Method with Applications to Metal Oxide Semiconductor Field Effect Transistors
Authors: Kosina Hans , Selberherr Siegfried
Published: February 2005

To describe the electron transport in both the high and low field region of a semiconductor device more accurately a method to couple Monte Carlo and drift-diffusion model has been developed. The space dependent parameters occurring in the drift-diffusion equation are calculated by means of the Monte Carlo method. Their definitions are derived from the Boltzmann transport equation without restricting assumptions about the underlying band structure. With this method regional Monte Carlo device analysis can be performed. The transport coefficients have to be calculated just in the high field region by the computationally demanding Monte Carlo method, thus including non-local effects such as velocity overshoot and ballistic transport, whereas in the remaining regions the solution of the drift-diffusion current relation with local parameters is sufficient.
Hot Carrier Relief of Metal Oxide Semiconductor Field Effect Transistor by Using Work-Function Engineering
Authors: Schwalke Udo , Hänsch Wilfried , Lill Arnulf
Published: February 2005

A detailed analysis of hot-carrier-degraded NMOS and PROS devices with either n+ or p+ gates is presented. For this analysis, we utilized a new simulation tool which allows direct monitoring of the buildup of charge and interface states during the DC stress experiments. The impact of the work-function difference of the n+ and p+ gate material on the injection conditions of hot carriers into the gate oxide will also be considered. Our results indicate that both NMOS and PMOS FETs with p+ gates are superior regarding hot-carrier stability.
Ion Energy Distributions at the Electron Cyclotron Resonance Position in Electron Cyclotron Resonance Plasma
Authors: Samukawa Seiji , Nakagawa Yukito , Ikeda Kei
Published: February 2005

The extremely high selective phosphorus-doped polycrystalline silicon etching is achieved at the electron cyclotron resonance (ECR) position in a new developed ECR plasma etching system. To characterize these etching results, the ion energy distribution in an ECR plasma is measured. The mean ion energy and the width of ion energy distribution decrease as they near the ECR position. The ECR position in the ECR plasma has a high ion current density and low ion energy at the same time. These characteristics correspond to the etching results.
A Model for SiNx CVD Film Growth Mechanism by Using SiH4 and NH3 Source Gases
Authors: Ishitani Akihiko , Koseki Shiro
Published: February 2005

This paper theoretically explores the SiN
x
CVD film growth mechanism by means of the ab initio molecular orbital method. In a chemical vapor deposition (CVD) reactor, an SiH4 and NH3 gas mixture produces silylenes (X-Si-Y: X and Y are substituents). The insertion of silylene into a surface Si-H or N-H bond is the important part of the CVD film growth mechanism. Following the insertion, H2-elimination reaction occurs from the surface. The film growth mechanism explains Si-H and N-H bonds remaining ih an SiN
x
film and the deviation from the stoichiometry. Based on the mechanism, it is suggested that a new source gas, SiNH5, instead of SiH4 deposits a stoichiometric SiN
x
film, and that a transition layer exists between the native oxide and the bulk SiN
x
film.
Fabrication of Storage Capacitance-Enhanced Capacitors with a Rough Electrode
Authors: Hayashide Yoshio , Miyatake Hiroshi , Mitsuhashi Junichi , Hirayama Makoto , Higaki Takashi , Abe Haruhiko
Published: February 2005

In order to produce high-performance capacitors with a rough surface polysilicon film as a storage electrode, we investigate various fabrication conditions for polysilicon films. We fabricated such capacitors that attained 1.55 times as much capacitance as those with a conventional polysilicon electrode. Capacitors with the rough electrode show almost identical leakage current characteristics to those of conventional ones. In the evaluation of their reliability, we found that they have lifetimes of more than 1×1010 seconds, which is sufficient for next-generation DRAM applications.
Numerical Simulations of Amorphous and Polycrystalline Silicon Thin-Film Transistors
Authors: Hack M. , Shaw J. G. , LeComber P. G. , Willums M.
Published: February 2005

In this paper we present results of two-dimensional numerical simulations of both amorphous silicon and NMOS and PMOS polycrystalline silicon thin-film transistors. Both types of devices are modeled using an effective medium approach whereby the defects and grain boundaries in the material are treated as a spatially uniform density of localized states in the band gap. The field-effect mobility is self-consistently calculated from the appropriate band mobility and using one set of parameters for each material we obtain very good agreement between simulations of both output and transfer characteristics and experimental data. The experimental activation energy of the source-drain current for the polycrystalline devices is also found to be in excellent agreement with the numerical simulations.
Top-Gate Amorphous-Silicon Thin-Film Transistors Produced by CVD Method
Authors: Kanoh Hiroshi , Yasukawa Masahiro , Sugiura Osamu , Breddels Paul A. , Matsumura Masakiyo
Published: February 2005

Chemical-vapor-deposited (CVD) amorphous-silicon films have been applied as the active layer in thin-film transistors with a top-gate structure for the first time. The maximum field-effect mobility and the typical on/off current ratio were more than 0.5 cm2·V-1·s-1 and 107, respectively. The characteristics were better than the ones based on plasma-enhanced CVD.
Large-Area Doping Process for Fabrication of poly-Si Thin Film Transistors Using Bucket Ion Source and XeCl Excimer Laser Annealing
Authors: Kawachi Genshiro , Aoyama Takashi , Suzuki Takaya , Mimura Akio , Ohno Yasunori , Konishi Nobutake , Mochizuki Yasuhiro , Miyata Kenji
Published: February 2005

A large-area doping process for polycrystalline Si (poly-Si) thin-film transistor addressed liquid crystal displays (TFT/LCD's) has been developed. A large ion beam that was extracted from the bucket ion source and a XeCl excimer laser were utilized for impurity doping and impurity activation. A sufficiently low value of sheet resistance (500±25 Ω/\Box) was obtained for an implantation time of 10 s. The poly-Si TFT's fabricated by using this technique have good characteristics and uniformity. This technique seems suitable for the fabrication of large area poly-Si TFT/LCD's.
High-Performance a-Si:H Thin Film Transistor Driven Linear Image Sensor with New Multiplex Structure for G4 Facsimile
Authors: Miyake Hiroyuki , Sakai Kazuhiro , Abe Tsutomu , Sakai Yoshihiko , Hotta Hiroyuki , Ito Hisao , Ozawa Takashi
Published: February 2005

A new 400DPI, A3 page width (310 mm) and 4864 dot, linear image sensor has been developed on a glass substrate. To achieve high speed and photoresponsivity for the G4 facsimile, the sensor has a new parallel multiplex structure called meander lines. The sensor can be driven at 4 MHz clock frequency, and its photoresponsivity is 20 V/lx ·s under a G54 fluorescent lamp. The reproduced image quality of the sensor is good for 8-point kanji characters.
Low-Temperature Polysilicon Thin Film Transistors by Non-Mass-Separated Ion Flux Doping Technique
Authors: Masumo Kunio , Kunigita Masaya , Takafuji Satoshi , Nakamura Nobuhiro , Iwasaki Atsushi , Yuki Masanori
Published: February 2005

A low-temperature, high-throughput self-aligned poly-Si TFT fabrication process has been developed. The process includes two key techniques. The first one is a laser-induced crystallization of a-Si occurring in the solid phase using a CW Ar+ laser beam with high scanning speed, which was previously reported. The second is large-diameter ion flux doping without mass separation. The maximum processing temperature is 450°C, which is sufficiently low for use of inexpensive glass substrates. With this process, excellent poly-Si TFT characteristics of I
on/I
off>106 and µFE=40 cm2/(V ·s) were obtained.
Numerical Analysis of the Optical Response Characteristics of Thin Film Transistor Addressed Liquid Crystal Displays
Authors: Numano Yoshinori , Hayama Masahiro , Yamazaki Teruhiko
Published: February 2005

A simulation method is proposed to analyze the optical response characteristics of TFT-LCDs. Our method using an equivalent circuit takes into account the time and voltage dependence of the dielectric constant of the TN-LC cell. We obtain good agreement between simulations of the optical response characteristics of the TN-LC cell and experimental results. The 30 Hz flicker, which appears in the optical rise state of the TFT-LCD, is analyzed by using our method. Our method enables a large amount of calculation of the optical response characteristics of TFT-LCDs at high speed.
Two-Dimensional Device Simulation for Polycrystalline Silicon Thin-Film Transistor
Authors: Yamada So , Yokoyama Shin , Koyanagi Mitsumasa
Published: February 2005

An accurate device simulator for polycrystalline silicon thin-film transistors is developed. In this simulator, the influences of grain boundaries (GBs) are incorporated into the mobility model, and the basic semiconductor equations are solved combining with the carrier generation/recombination model. As a result, it becomes possible to quantitatively analyze the influence of the GBs on the kink effect and the avalanche breakdown phenomenon, and the influences of the GB trap density and the grain size on the device characteristics.
Optical Absorption in Silicon Oxide Film Near the SiO2/Si Interface
Authors: Haga Takashi , Miyata Noriyuki , Moriki Kazunori , Fujisawa Masami , Kaneoka Tatsunori , Hirayama Makoto , Matsukawa Takayuki , Hattori Takeo
Published: February 2005

The contribution of SiO2/Si interface structure to optical absorption below the optical absorption edge of fused quartz was studied by measuring the reflectance of thermally grown ultrathin silicon oxide films. From the modified Kramers-Kronig analysis of reflectance, it was found that optical absorption at the photon energy of 7.8 eV arises from Si-Si bonds in the oxide film within 6 nm of the interface and does not depend on the oxidation temperature. Approximate areal density of Si-Si bond is 7×1014 cm-2
Particle Counting in Semiconductor Processing Gas and Apparatus with a New Flow-Cell-Type Laser Particle Counter
Authors: Ichijo Kazuo , Kondo Kaoru , Hoshina Tamio , Tsubouchi Kazuo , Masu Kazuya
Published: February 2005

A new flow-cell-type laser particle counter has been developed in order to measure particles at low and high pressure or in flammable and toxic gases. The minimum detectable particle diameter was 0.17 µm. The helium leak rate of this particle counter was lower than 2×10-11 atm ·cm3/s by using a double O-ring seal structure. We have successfully measured particles in a CVD apparatus at low pressure and in SiH4 gases.
The Role of Fluorine Termination in the Chemical Stability of HF-Treated Si Surfaces
Authors: Sunada Takeshi , Yasaka Tatsuhiro , Takakura Masaru , Sugiyama Tsutomu , Miyazaki Seiichi , Hirose Masataka
Published: February 2005

The principal role of silicon-fluorine bonds in the chemical nature of HF-etched Si surfaces has been investigated by angle-resolved X-ray photoelectron spectroscopy. The native oxide growth thickness and the fluorine coverage have been systematically measured as functions of HF concentration, pure water rinse time, air or N2+O2 gas exposure time and gas phase H2O concentration. It is shown that the native oxide growth is strongly suppressed by the existence of Si-F bonds of about 0.12 monolayers on the surface. This is explained by a model in which Si-F bonds chemically stabilize the surface reactive sites such as atomic steps as supported by the result of the layer-by-layer oxidation of Si.
A Vertical Integration of GaAs/GaAlAs LED and Vertical FET with Embedded Schottky Electrodes
Authors: Hong Chang-Hee , Kim Chang-Tae , Kwon Young-Se
Published: February 2005

A GaAs/AlGaAs surface-emitting light-emitting diode (LED) and a vertical field-effect transistor (FET) are vertically integrated using the selective atmospheric pressure metalorganic chemical vapor deposition (MOCVD) technique. The embedded Schottky metal between the epitaxial GaAs layers is employed as the gate electrode of the vertical driver FET. As the drain current of FET flows through the LED, the light output of LED is effectively controlled by the gate voltage of the driver FET. This device operates as a three-terminal optoelectronic device controlled by an electric input.