bluuebunny/crossref_metadata_2025 huggingface dataset:
Advantages of Fluorine Introduction in Boron Implanted Shallow p+/n-Junction Formation
Authors: Ohyu Kiyonori , Itoga Toshihiko , Natsuaki Nobuyoshi
Published: February 2005

The advantages of fluorine introduction on fabrication of shallow p+/n-junctions have been demonstrated. This was done by implanting fluorine onto the boron implanted p+/n-junction area prior to annealing. By introducing optimized amounts of fluorine, (1) the boron redistribution after annealing is suppressed, (2) the concentration of activated boron becomes higher, and (3) the leakage current level of the p+/n-junction decreases. These behaviors may be due to interactions between fluorine and defects in the silicon substrate or at the SiO2/Si interface.
Superconducting Property and Structure Studies of YBa2Cu3O7–Ag2O Composites
Authors: Lin J. J. , Chen Teng-Ming , Yao Y. D. , Chen J. W. , Gou Y. S.
Published: February 2005

We have studied the superconducting property and the structure of YBa2Cu3O7 added with Ag2O, with the weight ratios of YBa2Cu3O7 to Ag equal to 4, 6, 8, and 10. Resistance and magnetization measurements show that the normal-state transport behavior and the superconducting transition temperature, T
c, are insensitive to the amount of Ag added. The normal-state resistance decreases linearly with temperature, reaching a large value of \cong 3 for the ratio R(300 K)/R(100 K). This value is evidently larger than that (≤ 2.5) generally observed in polycrystalline YBa2Cu3O7, and is ascribed to the improved grain growth behavior resulting from Ag addition. X-ray diffraction and scanning electron microscopy studies have also been performed. X-ray diffraction study indicates the Ag peaks appear as a separate phase. Scanning electron microscopy study reveals large YBa2Cu3O7 grains (\cong20–60 µm). Finally, we point out that the microstructures of the samples depend much on the subtle preparation conditions.
Anisotropic Magnetoresistance of Amorphous Fe–Zr Alloy Films
Authors: Tsunashima Shigeru , Bayreuther Günther , Hoffmann Horst
Published: February 2005

Anisotropic magnetoresistance and related properties were measured for amorphous Fe100-x
Zr
x
(x=10, 14) films at temperatures between 20 K and the Curie point. The anisotropic magnetoresistance was found to be 0.4–0.5% at 20 K, decreasing with increasing temperature roughly in proportion to the third power of the magnetization. This agrees with the power law derived from the molecular field approximation.
ESR and Nonresonant Microwave Absorption in the High-TcPhase of the Bi(Pb)–Sr–Ca–Cu–O System
Authors: Tagaya Kimihito
Published: February 2005

ESR measurements were performed for the high-Tcphase of the Bi(Pb)–Sr–Ca–Cu–O system, and a clear ESR signal was observed. The angular variation of theg-value exhibited a uniaxial anisotropy. Similar measurements were performed for Ca2CuO3. A nonresonant microwave absorption was also observed, and the lower critical field was investigated.
Superconductivity in the Y–Sr–Ba–Ca–Cu–O System
Authors: Kurihama Tadashi , Iwasaki Kazuya , Izumi Takatoshi
Published: February 2005

Superconducting properties of YSrBaCaCu
x
O
y
(x=2, 3, 4, 5, 6, 8, 10, 11 or 12) were investigated by electrical resistivity, magnetic susceptibility and powder X-ray measurements. The samples with x ranging from 3 to 11 have superconducting transition points T
C with temperature ranging from 30 to 61 K. The powder X-ray diffraction analyses of all samples show that the samples have tetragonal or pseudotetragonal symmetry.
Studies of Relaxation Oscillations in Cu/CuCl Vapor Lasers by Comparison of Experiments with Computer Analysis
Authors: Taniguchi Hiroshi , Saito Hiroshi
Published: February 2005

The transient phenomenon of relaxation oscillation in copper vapor lasers is studied experimentally and theoretically. Relaxation oscillations are observed in the 510.6 nm laser line of discharge-pumped CuCl vapor lasers under appropriate conditions which are furthermore shown to agree with the theoretical considerations. Computer solutions of the coupled rate equations are obtained for an explanation of the relaxation oscillations. Comparisons with experimental observations show qualitative agreement.
A Relation Between Short and Open Circuit Measurements Due to the Motion of the Zero Field Plane
Authors: Ferreira G. F. Leal
Published: February 2005

A relation between short circuit current and open circuit voltage and its time derivative in samples initially at the same electric state is derived. Reference is made to an argument advanced by Yamanaka, Fukuda, Sawa and Ieda to explain results obtained in polyethylene samples, appeared in this Journal.
Thin-Film Single-Crystal Growth of BiI3 by a Hot Wall Technique
Authors: Takeyama Shojiro , Watanabe Katsuyosi , Komatsu Teruo
Published: February 2005

A hot wall technique has been applied to a layered compound material, BiI3, for growth of thin-film single crystals, utilizing van der Waals epitaxy on the selected layered-material substrates of PbI2 and CdI2. The thickness of the films ranged from 100 to 1000 Å. The quality of the films prepared under different growth conditions was evaluated by optical absorption spectra of a band-edge exciton, which turned out to be quite sensitive to the growth conditions of this material. The optimized conditions were established to obtain the best quality thin films, and consequently, it was found that crystal growth took place at very low temperatures around 50∼60°C.
A Molecular Beam Study of the Trapping and Desorption of Oxygen from Si(100) Surfaces
Authors: Miyake Tatsuya , Namiki Akira , Takemoto Takayuki , Soeki Shinya , Katoh Hiroyuki , Kamba Hideto , Suzaki Tetsuo , Nakamura Tetsurou
Published: February 2005

The trapping and desorption kinetics of oxygen on, Si(100) surfaces have been studied by a pulsed molecular beam method. The trapping process in a physisorbed well is a dominant process for the incident energy below 0.09 eV. Above 0.3 eV, the trapping probability decreases with increasing incident energy or with increasing surface temperature. The trapping process is explained by a simple hard cube model. The desorption yield increases with surface temperature for a low coverage surface. Taking the decrease in the sticking probability with surface temperature into account [M. P. D'Evelyn, et al.: Surf. Sci. 186 (1987) 75], this is direct evidence for the physisorbed oxygen-mediated dissociative adsorption which is considered to be an initial stage of the oxidation of Si. The activation energy for dissociative adsorption of physisorbed oxygen increases with oxygen coverage.
Resistivity Correction Factor for the Four-Probe Method: Experiment III
Authors: Yamashita Masato , Nishi Toshifumi , Kurihara Hiroshi , Enjoji Hideo , Iwata Atsushi
Published: February 2005

Experimental verification of the theoretically derived resistivity correction factor F is presented. Factor F is applied to a system consisting of a rectangular parallelepiped sample and a square four-probe array. Resistivity and sheet resistance measurements are made on isotropic graphites and crystalline ITO films. Factor F corrects experimental data and leads to reasonable resistivity and sheet resistance.
Segregation of Zinc in InGaAs/InP Heterostructures During Diffusion: Experiment and Numerical Modeling
Authors: Dildey F. , Amann M.-C. , Treichler R.
Published: February 2005

Zn diffusions from spin-on films were performed into InP/InGaAs/InP heterostructures suited for fabrication of heterojunction bipolar transistors. A strong segregation occurred at the InGaAs/InP heterojunctions enriching the Zn concentration in InGaAs by about an order of magnitude. From the Zn concentration profiles the relevant diffusion and segregation parameters were determined. Using these data an accurate numerical modeling and improved process control of the Zn diffusion into InGaAs/InP multilayer heterostructures can be achieved.
Preliminary T-T-T Curve of Bi–Pb–Sr–Ca–Cu–O Thin Films
Authors: Lin W. J. , Wang L. C. , Lu H. B. , Lin I. N. , Young C. C. , Lin W. Y. , Yang S. J. , Hsu S. E.
Published: February 2005

Films of Bi–Pb–Sr–Ca–Cu–O with desired 2201, 2212 and 2223 phases have been successfully prepared by means of DC magnetron sputtering and precise control of the postannealing process. A preliminary temperature-time-transformation (T-T-T) diagram is proposed from the observation. Pb-loss control is found to be crucial to the high-T
c (2223) phase obtained by the postannealing process, a higher PbO content in the films is observed to extend the temperature region of availability of the high-T
c phase and vice versa.
A Magnetically Induced Anomalous Ring Flame and Quenching Characteristics of Butane Flames
Authors: Aoki Takashi
Published: February 2005

A butane diffusion flame is quenched when encircled with magnetic gradient fields. This phenomenon originates from magnetic forces F

r
which accelerate combustion products and O2-decreased air in the direction of the flame, thereby resulting in a shortage of oxygen supply. Under a constant value of a gap width d between the magnet poles, the time τq needed for the quenching decreases with increasing current I in a magnet coil because F

r
increases with increasing I. Under a constant value of I, τq decreases with decreasing d because F

r
increases with decreasing d. It has been found that the flame-light intensity more than doubles, and that an anomalous ring flame appears under certain conditions of magnetic gradient, gap width, etc.
Measurements of Cloud Densities Surrounding Impurity Carbon Pellets
Authors: Ozaki Tetsuo , Morita Shigeru , Kawatoh Eizou
Published: February 2005

Cloud densities surrounding plastic carbon impurity pellets (polystyrene) injected into high-temperature hydrogen plasma are measured from Stark broadening of spectral lines. The line profiles from carbon ions are observed by a 1 m visible spectrometer and multichannel optical system. Electron densities measured from C+ and C+5 ions are 1-1.5×1017 and 4×1014 cm-3, respectively. The results are compared with calculations from an ablation model.
X-Ray Photoelectron Spectroscopy Using A Focused 300 µm-Diameter X-Ray Beam
Authors: Ninomiya Ken , Honda Kazunari , Aoki Sadao , Suzuki Keizo
Published: February 2005

A Au(4f) XPS spectrum has been obtained for a Au thin film deposited on a fine W wire using a 300 µm-diameter X-ray beam (MgKα, 1253.6 eV) produced by a Wolter type I mirror. The Au(4f) photoelectron count rate has also been measured as a function of beam center position when the focused beam is moved across the sample surface. This is the first microscopic XPS measurement that has been achieved using the Wolter type mirror. The observed count rate (6–7 cps) and its change across the sample surface are compared with the Au(4f) photoelectron count rates calculated in consideration of the focused X-ray beam intensity profile and the geometric configuration of the XPS measurement system. The present results suggest that XPS analysis in the micrometer range is possible with a highly brilliant X-ray source.
Large-Area MOVPE Growth of AlGaAs/GaAs Heterostructures for HEMT LSIs
Authors: Tanaka Hitoshi , Tomesakai Nobuaki , Itoh Hiromi , Ohori Tatsuya , Makiyama Kozo , Okabe Tadao , Takikawa Masahiko , Kasai Kazumi , Komeno Junji
Published: February 2005

We report the large-area metalorganic vapor phase epitaxy growth of AlGaAs/GaAs heterostructures for high-electron-mobility-transistor LSI applications. We used a barrel reactor with a load capacity of twelve 3-inch wafers. Wafer rotation results in ultrauniform epitaxial layers. The variations in both layer thickness and the carrier concentration of a Si-doped AlGaAs layer are less than ±1% over an entire 3-inch wafer. Wafer-to-wafer variations among the twelve wafers are ±1.1% for layer thickness and ±1.8% for the carrier concentration. The particle density on an epitaxial layer is less than 10 cm-2.
Influence of Beam Current Ripple on Secondary Electron and RBS Mapping Images
Authors: Agawa Yoshiaki , Takai Mikio , Ishibashi Kiyotaka , Hirai Kouichi , Namba Susumu
Published: February 2005

The influence of beam current ripple on Rutherford backscattering (RBS) and secondary electron mapping images using 400 keV He+ ion beams with a beam spot size of about 1 µm has been investigated to clarify the degradation of mapping images due to the current fluctuation. It was found that the secondary electron mapping images were deteriorated by a beam fluctuation of more than a few percent, while the RBS mapping image was rather insensitive to fluctuations of up to 50%.
Formation of KrF Excimer Using a Laser-Induced Harpooning Reaction through Two-Photon Pumping
Authors: Hakuta Kohzo , Nakayama Kunihiko , Fujino Masashi , Takuma Hiroshi
Published: February 2005

A new formation process of the KrF excimer by irradiating the Kr/F2 gas mix with KrF laser beam is reported. The formation process is assigned as a laser-induced harpooning reaction through two-photon pumping. This process has made it possible to prepare KrF excimers in highly excited vibrational states under simple and control lable conditions, and has enabled the quantitative investigation of the vibrational relaxation processes of the KrF excimer.
A Study of Cold Dopant Sources for Gas Source MBE: The use of Disilane as an N-Type Dopant of AlxGa1-xAs (x=0–0.28) and Trimethylgallium as a P-Type Dopant of GaAs
Authors: Sandhu Adarsh , Fujii Toshio , Ando Hideyasu , Ishikawa Hideaki
Published: February 2005

Disilane (Si2H6) was shown to be a suitable n-type gaseous dopant source for the gas source MBE (GSMBE) growth of Al
x
Ga1-x
As (x=0–0.28) using arsine, triethylgallium and triethylaluminium as host material sources. The carrier concentration of the Al
x
Ga1-x
As epilayer was controlled between 5×1017–2×1018 cm-3 (x=0–0.28) by varying the Si2H6 flow rate from 0.3 to 10 sccm. Furthermore, the hole concentration of GaAs grown using trimethylgallium as both the dopant and also the host material source, was controlled from 1.3×1020 to 6.3×1018 cm-3 by varying the V/III ratio from 0.5 to 6.5.
Effects of PN-Junction on Negative Differential Resistance of InGaAs/InAlAs Multiple Quantum Well Resonant Tunneling Diodes
Authors: Kawamura Yuichi , Asai Hiromitsu , Naganuma Mitsuru
Published: February 2005

Effects of the pn-junction on the negative differential resistance (NDR) of InGaAs/InAlAs multiple quantum well resonant tunneling diodes (MQW-RTD) are studied. It is found that in order to observe a clear NDR, a pn-junction is necessary when the electrode (cladding) layers on both sides of the MQW layer are composed of wide-band-gap InAlAs layers. This is explained by the recombination of electrons with holes near the p-InAlAs electrode layer.
Properties of Metalorganic Precursors for Chemical Vapor Deposition of Oxide Superconductors
Authors: Zama Hideaki , Oda Shunri
Published: February 2005

In an attempt to improve the reproducibility of chemical vapor deposition of YBaCuO films from metalorganic compounds, we have investigated some properties of several metal β-diketonates by means of thermogravimetric analysis and mass spectroscopy. The results suggest that Ba-compounds should be vaporized under a reduced pressure of as low as 1 Torr. The vaporizing temperature becomes 180°C, being separated from the decomposition temperature of 250°C. Mass spectra of several metal β-diketonates have been obtained for the first time by paying much attention to the vaporizing temperature and ionization voltage.
Critical Current Densities of Y1-xCaxBa2Cu4O8 (x=0 and 0.1) Superconducting Ceramics
Authors: Miyatake Takayuki , Yamaguchi Koji , Takata Tsutomu , Gotoh Satoshi , Koshizuka Naoki , Tanaka Shoji
Published: February 2005

From magnetization measurements of Y1-x
Ca
x
Ba2Cu4O8 superconducting ceramics with critical temperatures T
c of 83 K for x=0.0 and 91 K for x=0.1, the critical current densities, J
c(H), at 5 K and 77 K are obtained by employing the Bean critical-state model. The J
c at 77 K is evaluated to be 1.5×103 A/cm3 at 2 kOe for the sample of x=0.1. Compared with YBa2Cu3O7, the J
c(H) values in Y1-x
Ca
x
Ba2Cu4O8 are lower and more sensitive to the magnetic field. These J
c(H) properties are discussed on the basis of the superconducting properties, i.e., critical fields and Ginzburg-Landau parameters.
Textured Thick Films of Bi2Sr2Ca1Cu2Ox
Authors: Dietderich Daniel R. , Ullmann Bernd , Freyhardt Herbert C. , Kase Junichiro , Kumakura Hiroaki , Togano Kazumasa , Maeda Hiroshi
Published: February 2005

Thick textured films of Bi2Sr2Ca1Cu2O
x
are obtained by partially melting and slow cooling doctor-blade-processed tapes. Heat treatment between 890 and 870°C produces aligned microstructures on substrates of either Ag or Ag coated MgO. During heat treatment dissolution of Ag into the liquid oxide occurs. Because silver lowers the melting point of the oxide, the processing temperatures must be increased by about 10°C when an MgO substrate is used. The resulting films show that the oxide surface plays an important role in grain alignment. The Bi2Sr2Cu1O
x
phase, stable for temperatures greater than about 870°C, always transforms to the desired Bi2Sr2Ca1Cu2O
x
phase regardless of the heat treatment history (quenched from 890°C and annealed at 870°C or slowly cooled from 890°C to 870°C). The texture of the microstructure, however, is dependent upon the heat-treatment path, with a higher texture obtained with slower cooling.
Heteroepitaxial Growth of Y-Ba-Cu-O/Bi-Sr-Cu-O/Y-Ba-Cu-O
Authors: Harada Keizo , Tanaka Saburo , Itozaki Hideo , Yazu Shuji
Published: February 2005

Heteroepitaxial films of YBa2Cu3O7-x
/Bi2Sr2CuO
y
/YBa2Cu3O7-x
have been successfully grown using the in situ process. The RHEED pattern of each layer observed in situ showed streaks. The result of cross-sectional transmission electron micrograph (TEM) observation indicates virtually no disruption at the interfaces with the 6 nm-thick intermediate layer. Temperature dependence of resistance through the trilayer also indicates that there is no disruption which would cause short passes for supercurrent between the top and base superconducting layers.
GaInAsP/InP Semiconductor Multilayer Reflector Grwon by Metalorganic Chemical Vapor Deposition and its Application to Surface Emitting Laser Diode
Authors: Imajo Yoshihiro , Kasukawa Akihiko , Kashiwa Susumu , Okamoto Hiroshi
Published: February 2005

A GaInAsP/InP multilayer reflector was fabricated by low pressure metalorganic chemical vapor deposition. Peak reflectivity of as high as 0.98 was obtained, which was in good agreement with the calculated value. This multilayer reflector was applied to a 1.5 µm GaInAsP/InP vertical cavity surface emitting laser diode, and room temperature pulsed oscillation was achieved for the first time with a threshold current density of 124 kA/cm2.
Optical Modulation of the Signal in Total Internal Reflection Light Modulator Utilizing Bismuth Silicon Oxide
Authors: Kim Sangkuk
Published: February 2005

Utilizing the high photoconductivity of bismuth silicon oxide, we fabricated a total internal reflection light modulator in which optical modulation of the signal is possible. The modulation is implemented by photoconductive collapse of the electric field distribution surrounding a given electrode pair, which results in reduced diffraction efficiency. We discuss the operational characteristics of the resulting optical modulation.
13C NMR Observation of Molecular Motions at the Smectic-A-Smectic-C (Smectic-C*) Transition in a Recemic (Chiral) Smectic Liquid Crystal
Authors: Yoshizawa Atsushi , Kikuzaki Hiroshi , Hirai Toshihiro , Yamane Mamoru
Published: February 2005

We have studied molecular motions and the microscopic environment at the SmA-SmC (SmC*) transition in a racemic (chiral) smectic liquid crystal by means of 13C NMR with CP/MAS and without sample spinning. Fast overall fluctuation caused by the existence of the molecular chirality has been observed in the SmA phase by T
1 measurements. Static NMR spectra indicate that the conformation of the enantiomer in the SmC* phase is different from that of the corresponding racemic compound in the SmC phase.
Effects of Ammonia on the Growth of ZnSe by Metalorganic Chemical Vapor Deposition
Authors: Morimoto Keizo
Published: February 2005

The electrical and luminescence properties of ZnSe films grown on GaAs(100) substrates by metalorganic chemical vapor deposition in an atmosphere of dilute ammonia have been investigated. The observed properties correlate well with each other. The growth rate R
G and the electron mobility at low temperatures increased markedly. Films with a maximum mobility of more than 10000 cm2/(V ·s) at 40 K have been obtained at R
G>20 µm/h. It is suggested that active hydrogen produced by the decomposition of ammonia expedites the decomposition of dimethylzinc on the film surface and reduces carbon contamination.
Low-Temperature Si Surface Cleaning by Hydrogen Beam with Electron-Cyclotron-Resonance Plasma Excitation
Authors: Shibata Tomohiro , Nanishi Yasushi , Fujimoto Masatomo
Published: February 2005

Si surface cleaning is successfully carried out at as low as 400°C using hydrogen ECR plasma. SIMS analysis reveals no detectable accumulation of either carbon or oxygen at the grown-layer/Si interface. Hydrogen plasma cleaning is found equally effective for unbiased and positively biased Si substrates. On the other hand, helium plasma is not as effective as hydrogen plasma for cleaning. These results imply that the major mechanism involved in the plasma cleaning is chemical reaction between silicon oxide and chemically active hydrogen radicals, rather than physical bombardment by hydrogen ions.
Observation of Liquid Crystals on Graphite by Scanning Tunneling Microscopy
Authors: Shigeno Masatsugu , Mizutani Wataru , Suginoya Mitsuru , Ohmi Manabu , Kajimura Koji , Ono Masatoshi
Published: February 2005

Molecules of liquid crystals adsorbed on graphite were observed by scanning tunneling microscopy (STM). Liquid crystals of both smectic and nematic phases provided periodic STM images of 3-nm-spacing lines, seemingly composed of molecules with their axes vertical to the line. Detailed investigation of the images revealed that several different patterns existed in smectic liquid crystal. On the other hand, nematic liquid crystal exhibited one reproducible pattern. Monolayer, multilayer, and dimer-based molecular arrangements are discussed. Models for the molecular arrangement of the nematic liquid crystal are proposed.
Surface Profiling Using the Photothermal Displacement Method
Authors: Umeda Norihiro , Itoh Ken-ichi
Published: February 2005

This paper describes a surface profile measurement by the photothermal displacement method. This technique is based on the thermal expansion of a sample absorbing a pumping beam and on the change in the deflection of a reflected probe beam due to the slope of displacement. A vertical resolution of about 0.1 µm is experimentally obtained. The surface profile measurement of a Mn-Zn ferrite magnetic head is demonstrated.
A New Ion Counting System Devised for Mass-Selective Detection of Sputtered Neutrals in Laser SNMS
Authors: Ichimura Shingo , Goto Keisuke , Kokubun Kiyohide , Shimizu Hazime , Matsuura Shigeki
Published: February 2005

A new ion counting system was devised for time-of-flight mass detection in sputtered neutral mass spectrometry (SNMS), using a pulse laser for postionization. A microchannel plate (MCP) intensifier used as a detector was gated by a retarding grid in front of the MCP for particular masses. High peak-counting ability (exceeding 1010 counts per second) of the system for ionization with a laser pulse (20–30 ns) was maintained for mass-selective detection. The performance of the new counting system at a high count rate was analyzed, and the detection limit and the accuracy were discussed.
Fabrication of First-Order Gratings for GaAs/AlGaAs LD's by EB Lithography
Authors: Suehiro Masayuki , Hirata Takaaki , Maeda Minoru , Hosomatsu Haruo
Published: February 2005

High-precision first-order gratings, 110 nm pitch, for GaAs/AlGaAs LD's were successfully fabricated using EB lithography. The field stitching error of EB lithography caused by height difference between reference marks for calibration and the samples, was reduced to 5 nm by controlling the EB deflection voltage calibrated by the detection of the position of the marks on the samples. We also investigated the effect of field stitching error on lasing characteristics using measurement and calculation. We found that a 20 nm stitching error is sufficiently small for single-mode LD operation.
Fabrication of Submicron Contact Hole with a Focused Ion Beam
Authors: Yasuoka Yoshizumi , Harakawa Kenichi , Gamo Kenji , Namba Susumu
Published: February 2005

In order to obtain reproducibility for fabricating microcontact holes in insulator film on the semiconductor substrate, a method of controlling focused ion beam irradiation by monitoring the absorption current was examined. The holes which penetrated the insulator (SiO2) film and just reached the surface of the semiconductor (Ge) substrate were fabricated by stopping the irradiation of the ion beam just after the absorption current of the sample passed through its maximum value. Using this method, holes with a contact area of the order of 10-10 cm2 were obtained with good reproducibility.
Experimental Demonstration of Novel Dynamical Memory Function in a Nonlinear Electro-Optical Ring Resonator
Authors: Aida Tahito , Davis Peter
Published: February 2005

We demonstrate control of nonlinear oscillations to realize a novel memory function in a simple optical device, a hybrid electro-optic ring resonator. Input digital codes are used to selectively excite stable nonlinear oscillation modes in the device. The modes can be easily decoded with intensity thresholding. Modes with bit capacity up to 21 bits have been switched, thus demonstrating the potential for large capacity optical devices.
Inference Engine Using Optical Array Logic
Authors: Iwata Masaya , Tanida Jun , Ichioka Yoshiki
Published: February 2005

An implementation method for an inference engine using optical array logic is presented. Optical array logic is a technique for parallel neighborhood operation using spatial coding and 2-D correlation. For efficient execution of inference in artificial intelligence problems, a large number of data must be searched effectively. To achieve this demand, we apply a template matching technique to the inference operation. By introducing a new function of data conversion, the inference operation can be implemented with optical array logic, which utilizes parallelism in optical techniques.
Optical Pattern Fuzzy Logic
Authors: Liu Liren
Published: February 2005

An optical two-stage system with multi-imaging and thresholding is described in this paper to execute the parallel fuzzy logic function in disjunctive or conjunctive normal form. On this basis, the parallel fuzzy logic functions are suggested to process the images of continuous grey level. Examples are given on nonlinear transformation, thresholding, and comparison between two images.
Optical Implementation of a Second-Order Neural Network Discriminator Model
Authors: Horan P. , Uecker D. , Arimoto Akira
Published: February 2005

Some of the symmetries inherent in a second-order translation invariant classifier model are described. The operational characteristics of this model for pattern recognition tasks such as fault and noise tolerance are explored. A particular optical architecture is detailed which exploits particular features of the model suited to optics and the operation of this system described.
Selective Area Epitaxy of GaAs Using GaAs Oxide as a Mask
Authors: Hiratani Yuji , Ohki Yoshimasa , Sugimoto Yoshimasa , Akita Kenzo , Taneya Mototaka , Hidaka Hiroshi
Published: February 2005

The use of GaAs oxide as a mask material for in situ selective-area epitaxy of GaAs by metal organic molecular beam epitaxy (MOMBE) was studied. The GaAs oxide mask was patterned by electron-beam-induced chlorine etching. Using trimethylgallium (TMG) and As4 as source materials, an epitaxial layer of GaAs was obtained on the opening of the GaAs oxide mask; no deposition was observed on the GaAs oxide. An observation of the thermal decomposition of TMG by mass spectrometry indicated that the thermal decomposition of TMG occurred above 350°C on an arsenic-stabilized surface, while decomposition did not occur below 550°C on the GaAs oxide surface. This surface-catalyzed reaction explains the selectivity of GaAs growth.
5 nm Gate Oxide Grown by Rapid Thermal Processing for Future MOSFETs
Authors: Fukuda Hisashi , Uchiyama Akira , Hayashi Takahisa , Iwabuchi Toshiyuki , Ohno Seigo
Published: February 2005

Formation of 5-nm-thick SiO2 film has been studied by rapid thermal processing (RTP). The SiO2/Si(100) interface of 5-nm RTP-grown SiO2 film evaluated by high-resolution TEM is quite uniform, at least ordered within one or two atomic layers. The TDDB characteristics have indicated that short-time breakdown failure diminishes with decreasing oxide thickness, drastically below 6 nm in thickness. However, leakage current at low field, which is related to oxide wear-out, is observed in ultrathin RTP-SiO2 film (<6 nm). We have applied 5-nm-thick RTP-SiO2 as a gate oxide of MOSFETs and obtained sufficient subthreshold and transconductance characteristics as device performance.
Role of Hydrogen Atoms in the Formation Process of Hydrogenated Microcrystalline Silicon
Authors: Nomoto Katsuhiko , Urano Yuichi , Guizot Jean Luc , Ganguly Gautam , Matsuda Akihisa
Published: February 2005

We have investigated the role of hydrogen atoms in the formation process of the hydrogenated microcrystalline silicon ( µc-Si:H) by using a layer-by-layer deposition technique in which an abundance of H atoms were supplied after the growth of every several monolayers of films. It has been found that whether or not µc-Si:H is formed is strongly dependent on the parameters (substrate temperature and waiting time before the growth of every several monolayers after H2 plasma is turned off) which change the hydrogen coverage of the top surface. These experimental results illustrate the idea that the major role of H atoms for µc-Si:H formation is not to make “growth-zone” reactions below the top surface but to achieve sufficient hydrogen coverage of the top growing surface.
Coevaporation Effect of Te on P-Type CdTe:Cu Film Formation
Authors: Nishitani Mikihiko , Hisamoto Kazue , Ikeda Mitsusuke , Hirao Takashi
Published: February 2005

Cu-doped CdTe films were prepared by coevaporation of CdTe and Cu, and the effect of the additional Te vapour supplement during the coevaporation was studied. It was found that the Cu-doped CdTe films coevaporated under a sufficient additional supplement of Te vapour were about one order of magnitude more conductive than other Cu-doped CdTe films in this work. From measurement of X-ray diffraction and Hall effect, it was concluded that the additional Te vapour supplement enhanced the p-type conductivity of the Cu-doped CdTe film due to the more effective doping of Cu impurities as acceptors into the Cd sites.
Formation of a Cu-Al-Se Phase with a Long-Range Order by Molecular Beam Epitaxy
Authors: Morita Yoshio , Narusawa Tadashi
Published: February 2005

A new phase in the Cu-Al-Se system was found on GaP substrates under growth conditions of an excess Cu vapour pressure and a growth temperature of 1073 K by use of molecular beam epitaxy. The mean composition of this film is close to the formula Cu3AlSe5, and differs considerably from the chalcopyrite structure compound CuAlSe2. We provide the first evidence of the presence of a new Cu-Al-Se phase with a long-range order.
MOS-Type Micro-Oxygen Sensor Using LaF3 Workable at Room Temperature
Authors: Katsube Teruaki , Hara Masashi , Serizawa Izumi , Ishibashi Norio , Adachi Nobuo , Miura Norio , Yamazoe Noboru
Published: February 2005

A sputtered LaF3 film was applied to construct a semiconductor micro-oxygen sensor consisting of a Pt/LaF3/SiO2/n-Si/Al structure. The sensor showed a stable response in the oxygen partial pressure range of 0.1–1.0 atm at ambient temperature. The sensitivity and response time strongly depended on the fabrication conditions of LaF3 and Pt films, and the optimum sputtering conditions to prepare the films were investigated. It was also demonstrated that water vapor treatment was effective in improving the response rate and the response reversibility.
Influences of Nb Addition on Superconducting Properties in Bi, Pb-Sr-Ca-Cu-O Glass-Ceramics
Authors: Nasu Hiroyuki , Kuriyama Nobuya , Kamiya Kanichi
Published: February 2005

The influences of Nb addition on superconducting properties in Bi, Pb-Sr-Ca-Cu-O glass-ceramics were investigated. The glass-forming tendency decreased as Nb contents increased, and a superconducting phase appeared even in asquenched bodies. The T
c(onset) and T
c(end) were strongly dependent on the Nb concentration, and the highest T
c(end) was 102 K for Bi1.6Pb0.4Nb0.2Sr1.9Ca2Cu3O
x
. The increase of T
c is basically related to the change in melting points caused by the addition of Nb.
Diffusion Bonding of Bi-Pb-Sr-Ca-Cu-O High-Tc Superconductors
Authors: Mutoh Yoshiharu , Inoue Michihiro , Komatsu Takayuki
Published: February 2005

Diffusion bonding of Bi-system ceramic rods produced by the melt-pump-up method was accomplished without dissimilar insert materials under a wide range of bonding conditions. Results showed that T
c, J
c and shear strength of the bonded joints were almost identical to those of the bulk.
Large Vessels of High-TcBi-Pb-Sr-Ca-Cu-O Superconductor for Magnetic Shield
Authors: Hoshino Kazutomo , Ohta Hiroshi , Sudoh Eichi , Katoh Kazuhiko , Yamazaki Shigeru , Takahara Hidefusa , Aono Masakazu
Published: February 2005

We have developed a relatively large high-TcBi-Pb-Sr-Ca-Cu-O superconducting magnetic shield vessel of 150 mm in inner diameter, 320 mm in depth and 10 mm in thickness, which has a potential application for biomagnetic measurements with a SQUID. Magnetic fields inside the vessel were measured by using an RF SQUID magnetometer or measuring induced voltages in a pickup coil. The shielding factors, defined as the ratio of the magnetic field at 290 K to that at 77 K, were around 106. The high attenuation ratio indicates that magnetic shielding of high-Tcsuperconductor is promising for neuromagnetic measurements with SQUIDs.
Magnetic Flux Motion of Superconducting Bi-Sr-Ca-Cu-O Films after Ion Irradiation
Authors: Hoshiya Taiji , Takamura Saburo , Aruga Takeo , Kobiyama Mamoru
Published: February 2005

The temperature dependence of electrical resistance under applied magnetic fields was measured by the resistive method in polycrystalline Bi-Sr-Ca-Cu-O films after He ion irradiation at room temperature. The broadening of the transition temperature in the low resistance region was suppressed as the irradiation fluence increased. The effective activation energy was raised by ion irradiation. These changes are due to the presence of pinning centers produced by ion irradiation.
High Tc Superconducting Film Formation at the Bi-Pb-O/Sr-Ca-Cu-O Interface
Authors: Lee Kiejin , Lee Jaegab , Park Gwangseo
Published: February 2005

The high T
c superconducting films with a T
c (zero resistance) of 104 K were prepared by two liquid-phase-reaction steps at 830°C and 850°C with the mixture of Bi2O3 and PbO powders and Sr-Ca-Cu-O(Sr:Ca:Cu=2:2:4) ceramic substrates. The high T
c phase was well stabilized on the Sr2Ca2Cu4O
z
substrate with Bi2Pb0.6O
y
. The reaction steps, the role of PbO and microstructural analysis for the formation of high T
c films have been studied by XRD, DTA and SEM.
Electrical Properties of Boundary between YBa2Cu3O7-δ and Ba1-xKxBiO3 Thin Films
Authors: Enomoto Youichi , Moriwaki Kazuyuki
Published: February 2005

We have fabricated a contact between an epitaxially grown YBa2Cu3O7-δ thin film and a polycrystalline Ba1-x
K
x
BiO3 thin film. This contact exhibits the typical I-V characteristics of quasi-particle tunneling which are observed for junctions consisting of electrodes having different superconducting energy gaps. From the I-V characteristics, the superconducting energy gap, 2 Δ, is estimated to be 1.5 meV along the c-axis for YBa2Cu3O7 and 3 meV for Ba1-x
K
x
BiO3. The 2 Δ/k
T
c for the Ba1-x
K
x
BiO3 is about 3.5, which is equal to that derived from a boundary Josephson junction. These properties show that the contact boundary between YBa2Cu3O7-δ and Ba1-x
K
x
BiO3 works as the tunneling barrier.
Narrow-Linewidth Tunable Visible InGaAlP Laser, Application to Spectral Measurements of Lithium, and Power Amplification
Authors: Ohtsu Motoichi , Suzuki Hiromasa , Nemoto Kouhichi , Teramachi Yasuaki
Published: February 2005

Coarse and fine tuning of a 3.3 THz sweep range for an optically stabilized InGaAlP laser were realized for the first time by varying the angle of an external grating surface and the length of an external confocal Fabry-Perot cavity while maintaining the narrow linewidth of less than 50 kHz. Optogalvanic spectral shapes of D1 and D2 lines in Li vapor were measured by this laser, and the spectral splitting due to D.C. Stark effect was clearly observed. The laser power was amplified 25 dB by a dye solution which was optically pumped by the second harmonics of a pulsed YAG laser.
Transient Carrier Injection in Layered Organic Photoconductors
Authors: Aramaki Shinji , Murayama Tetsuo
Published: February 2005

Transient photocurrents within layered organic photoconductors using copper phthalocyanine and hydrazone derivatives were measured with two different means of carrier generation: one contained a carrier injection process between the two different layers and the other did not. By means of deconvolution of these two transients, the carrier injection rate was observed as a function of time. The injection rate of the layered photoconductor containing copper phthalocyanine and the hydrazone derivative had a long time tail. The observed low photoinjection efficiency of the transport material which possesses a high ionization potential is not attributed to recombination but to a broad distribution of carrier injection rates.
Electric-Field-Induced Transitions among Antiferroelectric, Ferrielectric and Ferroelectric Phases in a Chiral Smectic MHPOBC
Authors: Hiraoka Kazuyuki , Chandani A.D.L. , Gorecka Ewa , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

A T-E phase diagram of MHPOBC (C8H17O–--COO–-COO*CH(CH3)C6H13) has been obtained by means of the temperature (T) dependence of the dielectric constant under a dc biased electric (E) field. It is presumed from the T-E phase diagram that there is a temperature range where the field-induced antiferroelectric-ferrielectric-ferroelectric phase transitions take place. These transitions have been confirmed as five transmittance states between crossed Nicols under a triangular wave, i.e., ferro-ferri-antiferro-ferri-ferro. The field-induced antiferroelectric-ferrielectric phase transition has also been identified through conoscopic observation.
Photopolymerization for Orientated Liquid Crystalline Polymers under the Application of Electric Fields
Authors: Imanishi Yasuo , Kondo Katsumi , Kitamura Teruo
Published: February 2005

The photopolymerization of 4-4'-cyanobiphenylyl 4-(6-acryloyloxyhexyloxy)benzoate in the liquid crystalline phase was performed both with and without an external electric field, and controlled patterning in a film was achieved. Referring to the thermal behavior of the polarized light transmittance of the polymerized film, the possible coexistance of two different glass transition temperatures for the main chain and the mesogen groups in the polymer is discussed.
The Synthesis and Formation Process of a New Cubic Conductive Cu7O8-y(NO3) Compound
Authors: Yazawa Ichiro , Sugise Ryoji , Terada Norio , Jo Masatoshi , Oka Kunihiko , Hayakawa Hiroshi , Ihara Hideo
Published: February 2005

The synthesis and formation process of a new cubic conductive Cu7O8-y
(NO3) compound was studied. This material was formed as an intermediate compound in the decomposition process of copper nitrate by a firing process in oxygen flowing gas. It has a CuO2 plane in its lattice structure and is a parent material of the new metallic copper oxide compounds.
Ternary Phase Diagram of the YO1.5-BaO-CuO System and the In Situ Observation of Crystal Growth
Authors: Kawabata Sanemasa , Hoshizaki Hiroki , Kawahara Nobuaki , Enami Hiroyoshi , Shinohara Toshiyuki , Imura Toru
Published: February 2005

The ternary phase diagram of the YO1.5-BaO-CuO system was proposed based on the in situ observation of the transformation structures and their reaction temperatures in the growth process of YBa2Cu3O7-y
crystal from self-flux of various compositions. This phase diagram enables us to explain many phenomena in the growth process of YBa2Cu3O7-y
single crystals, such as flux flow and concentration deviation.
An Off-Equilibrium Property of Current Fluctuation Passing through Electrical Resistors
Authors: Agu Masahiro , Shimizu Kazuo , Okawa Shouichi
Published: February 2005

The property of time-reversal asymmetry of electrical direct current fluctuations x(t) passing through solid carbon resistors at 77 K was examined with the use of the asymmetrical correlation function <x(t)x
2(t+τ)-x
2(t)x(t+τ) >. Here  means the ensemble average of x. It is shown that the current fluctuations come to exhibit time-reversal asymmetry as the Joule heat generated by the current increases in the resistor. This experimental fact is interpreted in such a way that the current fluctuations tend to show a non-Markovian property (i.e., memory effect) as the Joule heat increases.
Experimental Demonstration of Optical Three-Layer Neural Network
Authors: Kasama Nobuyuki , Hayasaki Yoshio , Yatagai Toyohiko , Mori Masahiko , Ishihara Satoshi
Published: February 2005

An optical three-layer neural network using a microchannel plate spatial light modulator (MSLM) is firstly demonstrated. The back-propagation learning algorithm is used to calculate optimum weight matrices. Experimental results on learning of exclusive OR operation are presented.
Effect of Charged Defects on Properties of Amorphous Si-Based Alloys
Authors: Kumeda Minoru , Yoshita Masahiro , Morimoto Akiharu , Shimizu Tatsuo
Published: February 2005

Effects of both neutral and charged defects on optoelectronic properties have been investigated in a-Si:H, Si1-x
C
x
:H, Si1-x
N
x
:H and Si1-x
O
x
:H films by separating both kinds of defects. The increase in the density of neutral defects decreases the photoconductivity because they work as a recombination center for optically excited electrons in the conduction band. On the other hand, the increase in the density of charged defects increases the decay time of the photocurrent after the light-off because they work as a trapping center for the electrons.
Interdiffusion of Si and Ge Atoms during Gas-Source MBE of Ge on Si(100) at 500–800°C
Authors: Suemitsu Maki , Chiba Kazuhiro , Miyamoto Nobuo
Published: February 2005

Germanium growth on Si(100) using GeH4 gas-source molecular beam epitaxy has been performed in the temperature range of 500–800°C with the grown film thickness of about 1000 Å. From electron-probe microanalysis, Raman spectroscopy, and Auger electron spectroscopy measurements, it was indicated that a noticeable interdiffusion of Si and Ge atoms occurred during growth in this temperature range.
Correlation between Tc and Eu Lattice Vibration in T'-Phase Superconductor (La1-xEux)2-yCeyCuO4-δ Observed by 151Eu Mössbauer Effect
Authors: Itoh Hideaki , Kusuhashi Mikio , Taniwaki Masafumi
Published: February 2005

The electronic state and lattice vibration of Eu in T'-phase (La1-x
Eu
x
)2-y
Ce
y
O4-δ was studied by 151Eu Mössbauer effect. The isomer shift and the Debye temperature of Eu, \varThetaD, showed that Eu is trivalent, and the Eu-O distance is larger than those in the hole-doped superconductors. With increasing Eu concentration, in spite of the shortening of the lattice constants, \varThetaD in T'-phase decreased. This is probably caused by the increase in the Eu-O distance with the change of Eu-O-La bonding into Eu-O-Eu bonding. A tight correlation between T
c and \varThetaD was found and the relation, T
c=0.772\varThetaD exp
(-\varThetaD
2/13000), was derived.
Effect of Sulfur Doping on the Structure and Properties of La2-xSrxCuO4 Superconductor
Authors: Kozuka Hiromitsu , Fujihara Shinobu , Yoko Toshinobu , Sakka Sumio
Published: February 2005

Effects of the substitution of sulfur for oxygen on the structure and electrical properties of La1.84Sr0.16CuO4 superconductor have been studied. It was found that the superconducting transition temperature decreases, the temperature dependence of electrical resistance at low temperatures becomes semiconducting and the electrical resistance increases with increasing sulfur content. The crystal structure at room temperature changed from tetragonal to orthorhombic, while the in-plane lattice constants a and b increased and the lattice constant c decreased with increasing sulfur content.
Improvement of Critical Current Density in YBa2Cu3O6+x Superconductor by Sn Addition
Authors: Osamura Kozo , Matsukura Norikazu , Kusumoto Yukihide , Ochiai Shojiro , Ni Baorong , Matsushita Teruo
Published: February 2005

When SnO2 was added to Y-123 (YBa2Cu3O6+x
) powder and sintered at 1223 K for 86.4 ks, the densification was enhanced remarkably, and the density reached 99% of the theoretical value for the 2-mol%-SnO2-added specimen, while the average grain size became smaller with Sn addition. Fine spherical BaSnO3 precipitates were observed to be distributed in the grains and at grain boundaries. The AC magnetization measurements indicated that Sn addition causes intragrain J
c
m to increase at 77 K in the magnetic field between 0.02 and 0.12 T. The J
c
m exceeded 106 A/cm2 at 0.04 T for the 3-mol%-SnO2-added specimen.
Work Function of a High-Tc Superconductor, YBa2Cu3O7
Authors: Koshida Nobuyoshi , Saito Kazuya
Published: February 2005

To characterize the electronic properties of superconducting YBa2Cu3O7, its work function \varPhi has been measured by two different methods. From the photoelectric and electrical determinations, it is shown that \varPhi of polycrystalline YBa2Cu3O7 is close to 4.0 eV. The relatively high work function of YBa2Cu3O7 for its low electron density implies that a strong exchange-correlation potential exists in the bulk. Systematic studies are necessary in order to determine whether or not the work function is a useful parameter for the new high-T
c superconductors as well as for the conventional ones.
Suspension-Spun Tl-Ba-Ca-Cu Oxide Filament with High Critical Current Density
Authors: Goto Tomoko , Yamaoka Chiaki
Published: February 2005

High T
c Tl-(Ba, Sr)-Ca-Cu-O superconducting filaments were successfully prepared using a technique in which suspension-spun and pyrolyzed filaments were densified by pressing and sintering. A high J
c at 77 K, 0 T of 12000 A/cm2 was attained for the filament sintered at 840°C for 1200 s with a zero resistance state of 102 K. Although the starting powder had a high T
c phase of Tl2Ba2Ca2Cu3O
x
, the structure of the filament with high J
c was a high T
c phase of Tl1Ba2Ca3Cu4O
x
due to the volatility of Tl oxide from the large surface area of the filament.
Thin Film Structure of YBa2Cu3O7-δ on (001) MgO Substrate Studied by TEM
Authors: Suzuki Hajime , Kurosawa Hideyuki , Miyagawa Katsumi , Hirotsu Yoshihiko , Era Masanori , Yamashita Tsutomu , Yamane Hisanori , Hirai Toshio
Published: February 2005

A plan-view TEM observation was made for YBa2Cu3O7-δ (YBCO) thin films prepared by MOCVD on (001) MgO substrates. For the TEM observation, the MgO substrate plates were ion-thinned before the YBCO deposition. The YBCO thin films were found to be polycrystalline with a grain size of about 0.5 µm. Most of the YBCO grains are grown with their [001] axes nearly normal to the MgO substrate plane. Between the neighboring YBCO grains, a small-angle misorientation was observed quite frequently. Most of the misorientation angles measured by selected-area electron diffraction were less than about 5 degrees. At the small-angle grain boundaries, a nearly periodic array of dislocations was observed in the high-resolution lattice images. The AC and DC Josephson effects of YBCO thin film bridges reported previously are discussed in relation to the small-angle grain boundaries.