bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two–dimensional image–reconstruction method from holograms sampled by fresnel zone plates
Authors: Suzuki Yoichi , Yamashita Eikichi 
Published: July 2007

AbstractThe hologram of a single‐point object is called a Fresnel zone plate (FZP), and the hologram of a general object is represented as a superposition of FZP's. Since a point image can be reconstructed from the FZP at a reasonable location, there can be considered an image reconstruction method based on FZP. This paper proposes the FZP sampled hologram and the corresponding two‐dimensional image reconstruction method. The FZP sampled hologram is sampled with small interval at the central part and large interval at the periphery. By multiplying the phase function with the one‐dimensional hologram and performing the Fourier transform, the two‐dimensional image distribution can be determined for the azimuth and range. By analyzing the point‐image distribution, it is seen that the azimuth resolution of 6 mrad is obtained for the millimeter wave frequency of 35 GHz and the hologram length of 25 cm. It is seen also from the distribution that there exist side peaks of −4.8 dB at an azimuth angle of ± 11 mrad apart from the peak. An experiment was made for the millimeter‐wave holography with a simple object, and a satisfactory agreement with the theory was observed.
Substrate temperature dependence of perpendicular anisotropy for amorphous nickel ferrite films
Authors: Hiratsuka Nobuyuki 
Published: July 2007

AbstractAn amorphous nickel ferrite film was deposited by double source vacuum evaporation using Ni – Fe2 alloy and P2O5 sources. The film formed at the substrate temperature between 100 and 573 K showed an increase in the perpendicular anisotropy (Ku) as the substrate temperature increased. One reason for the increase in ku appeared to be due to a shape anisotropy caused by the formation of a columnar structure. Another reason seemed to be the decrease in the concentration of Fe2+ ions in the film. Specifically, since the deposited films were oxidized with an increase of the substrate temperature, the concentration of Fe2+ ions decreased and Ku increased. As the substrate temperature increased, the film became amorphous because the P2O5 content increased although the Ni/Fe ratio remained constant; P2O5 not only provided the oxygen to the NiFe2 film, but also played an important role in the formation of the amorphous state. The forementioned reaction accelerated as the substrate temperature increased. Therefore, this deposition method has been determined to be a kind of reactive evaporation technique.
Carrier conduction characteristics of si gate mnos memory device
Authors: Sato Kazuo , Hirano Kanji , Fukutomis Tsuyoshi , Misaki Hirozumi 
Published: July 2007

AbstractThe carrier conduction characteristics during erase and write in Si‐gate‐type MNOS memory devices with thin oxide (∼2 nm) have been investigated by comparison with the conventional Al‐gate type. As a result, it has been confirmed that as in Al‐gate type, the carrier injection between the substrate and the gate insulator is dominated by electron injection from the substrate into the gate insulator under positive gate bias, and by hole injection from the substrate into the gate insulator under negative gate bias. However, unlike in the conventional Al‐gate type, the carrier conduction mechanism in nitride for Si‐gate MNOS memory is determined by different mechanisms under positive and negative gate biases, attributed mainly to the difference in carrier injection from the gate electrode.
Lightning–surge observation using optical fiber
Authors: Kuwabara Nobuo , Koga Hiroaki , Motomitsu Tamio 
Published: July 2007

AbstractThis paper describes lightning‐surge characteristics induced in different terminations of subscriber paired cable due to the same lightning discharge and its measurement method using optical fibers. Lightning‐surge‐inducing mechanisms in telecommunication lines have been developed from lightning‐surge data and calculated lightning‐surge values. From the results of study, it has been clarified that: (1) lightning surges in the telecommunication line are induced mainly from the horizontal component of electromagnetic fields based on the lightning discharge; (2) lightning‐surge voltage in underground cable is almost the same value as the surge in aerial cable; and (3) lightning‐surge voltage is reduced by the metalsheath shielding effect based on the metal sheath grounding.
Characteristic of hydrogen storage of TixFe100‐x alloy thin film
Authors: Konish Ryösuke , Okasaka Yasuhiko , Imai Hiroshi , Osaki Tomoyuki , Harada Hisamochi , Sasakura Hiroshi 
Published: July 2007

AbstractThe dependence of amounts of absorbed hydrogen upon compositions of TixFe100‐x thin film is studied. The bonding states of these hydrogenated metal films also are investigated.The films of various compositions were prepared by a sputtering method using face‐to‐face targets. Compositions and structures of the films were measured by XPS, x‐ray diffraction and Mössbauer spectroscopy methods.After introduction of hydrogen into these films under the pressure 1 kg/cm2, the maximum amount of hydrogen was absorbed in Ti89Fe11 film. XPS measurements indicated that 2 p spectra of Fe and Ti shifted to the lower energy side, and the maximum shift was observed in Ti45Fe55 film. These results suggested that stable TiFe hydride was not formed in the film which absorbed the maximum amount of hydrogen, and large amounts of absorbed hydrogen were present as solid solution in the film.
Interface circuit between solar cell and commercial AC bus
Authors: Harada Koosuke , Murata Katsuaki 
Published: July 2007

AbstractSince the power generated by a solar cell depends strongly on the weather condition, particularly the intensity of the solar light, these cells are usually employed in combination with secondary batteries. However, the latter has problems in maintainability and safety. Therefore it is desirable to use ac power in place of a secondary battery if the solar cells are used in general households. For such a purpose, it is necessary to insert between the solar cell and the ac power source an inexpensive interface circuit that is simple and reliable. In this paper, an interface circuit made of a voltage‐controlled variable‐frequency oscillator, an inverter and a coupling inductor is reported. With this circuit, it became possible to extract an almost maximum power from the solar cell at the varying solar intensity. The output is converted to ac and connected automatically with the commercial ac source. The operating principle and the experimental results will be reported.
Cerenkov radiation from a relativistic electron beam propagating through a circular waveguide
Authors: Tanaka Toshiyuki , Yasumoto Kiyotoshi 
Published: July 2007

AbstractThe problem of Cerenkov instability by the relativistic electron beam propagating along a constant static magnetic field applied in the axial direction of the slow‐wave structure with a circular cross section is analyzed based on the relativistic equation of motion for cold electrons and Maxwell's equations. As practical slow‐wave structures, a circular corrugated waveguide, a coaxial corrugated waveguide, and a dielectric loaded waveguide have been assumed. The maximum growth rates of the space charge and cyclotron Cerenkov instabilities are calculated numerically for each structure. It is found that for both instabilities, the growth rate is the maximum in the case of a corrugated coaxial waveguide in which the electron beam is propagating near the waveguide wall. In all three slow‐wave structures, the growth rate of the cyclotron Cerenkov instability can be made substantially smaller than that of the space‐charge Cerenkov instability.
Detection of faults in optical fibers by the phase compensated reflectometer
Authors: Hangai Seiichiro , Kosaka Yoshihiro , Taki Yasuo 
Published: July 2007

AbstractThe Fresnel reflection is influenced strongly by defects in the optical fiber. As the fiber attenuation is decreased, the Fresnel reflection becomes useful for fault detection if it is measured accurately.This paper proves theoretically that the phase‐compensated reflectometer can be the optimum detection system of the Fresnel reflection when it is used for fiber‐defect detection. In addition, the results of computer simulations for some typical operating conditions for defect detection are shown.
Characteristics of the transient wafer temperature distribution in a furnace for semiconductor fabrication processes
Authors: Mokuya Kinji , Matsuba Ikuo , Aoshima Takaaki 
Published: July 2007

AbstractIn the high‐temperature process of semiconductors, the temperature distribution on the wafer surface during the procedures of the wafer insertion into and removal from the oxidation or diffusion furnace is important in determining the density of the dislocation due to the thermal stress and the uniformities of both the oxide thickness and the diffusion depth. As the size of a wafer and the density of integration increase, the analysis of the thermal transient characteristics becomes more important.This paper analyzes the model of the temperature transient characteristics proposed previously and describes the transient characteristics on a wafer by measuring the temperature distribution en a wafer in a furnace using an infrared radiometer.The simulation for a case where a wafer of 150 mm in diameter is inserted into a furnace at a speed of 20 cm/min indicates that the temperature variation on a wafer at every moment is as high as 150°C. This result agrees with the experimental result within an accuracy of 25°C. When the insertion speed is 100 cm/min, the temperature variation increases by 20 to 30 percent and is maintained until the wafer reaches the high‐temperature zone. This is caused by the increase in the rate of temperature change with time due to the radiation from the tube wall which is the external heat source. This tendency is more noticeable for waters located at the middle row.
Improved circular disk 3–dB hybrids
Authors: Ohta Isao , Hagino Ichiro , Kaneko Takenori 
Published: July 2007

AbstractMethods of improvement on a planar‐circuit‐type 3‐dB hybrid consisting of a four‐port circular disk‐shaped resonator are proposed and described. The characteristics of a conventional circular disk hybrid are degraded gradually by higher‐order modes of the disk resonator as the ratio of the disk radius to the port width decreases, i.e., as the center frequency becomes higher. This is caused mainly by the fact that the ports arrangement is based only upon the field distribution of the fundamental (1, 1) resonant mode (dipole mode). It is important in practice to prevent the deterioration of the hybrid characteristics because of the suitability of the hybrid for application at relatively high microwave frequencies. This is due to simplicity of its structure, and a small value of the ratio is desired for broadening the bandwidth. From the foregoing viewpoint, the purpose of this paper is to improve the hybrid characteristics without loss of simplicity. Great improvement is obtained by rearrangement of the four ports upon consideration of the higher‐order resonant modes and/or addition of a capacitive stub at the circumference of the resonator. Furthermore, the bandwidth of the hybrid is broadened considerably by adding an impedance step between the resonator and each 50‐Ω coupling port. These improvements also are confirmed experimentally.
High‐frequency switching regulator controlled by magnetic amplifier
Authors: Harada Koosuke , Member Takashi Nabeshima, 
Published: July 2007

AbstractBy taking a forward‐type converter, the control characteristics of a switching regulator controlled by a half‐wave magnetic amplifier were analyzed using the models of the dc‐magnetizing characteristic and the reverse recovery of the diode so that the relationship between the switching frequency and the controllable region were described quantitatively. The results show that the dead angle in a magnetic amplifier can represent a function of the dynamic resistance of the core and the magnetic permeability of the core, and that this in a high‐frequency operation cannot be determined by the rectangularity alone. When the magnetic amplifier is used for a pulse‐width modulator of a converter, the reverse recovery of rectifier diodes considerably affects the control characteristic of the magnetic amplifier, limiting its maximum on‐time at the frequency above a few hundred kilohertz. By using the model of the dc‐magnetizing characteristic, the power loss of the core is represented by a function of the parameters of the core and switching frequency so that the iron loss of the magnetic amplifier is expressed quantitatively.
Electromagnetic fields excited by an electric dipole located over a conducting concave spherical surface
Authors: Sawaya Kunio , Maeda Tadahiko , Members Saburo Adachi, , Member Yasuto Mushiake, 
Published: July 2007

AbstractThe dome antenna has been proposed for high‐speed scanning of the main beam of the antenna in a wide‐angle range. For the design of the dome antenna, an analysis for the electromagnetic field in the concave side of the conducting sphere is indispensable. In connection with this problem, several studies have been reported on the cylindrical concave surface. However, no report is available to date on the electromagnetic field for a practical concave conducting sphere for which both the source and the observation points are removed from the boundary. This paper describes the results of analysis for this type of electromagnetic problems. First, the integral expressions for the electric field are obtained in the form of a sum of Whispering Gallery (WG) modes and a continuous spectrum. In the derivation of the field expression, spurious diffracted waves are included due to a hypothetical conical absorber, and these waves are eliminated. A scheme is implemented in which the pole contribution of the wavenumbe in the zenith angle θ so that the numerical difficulty is removed. Actual numerical calculations have been performed and the validity and range of applicability have been studied for the expression. It is found that the expression derived in this paper provides a valid field solution for the case where kα (k is the wavenumber and α is the sphere radius) is sufficiently larger than unity and is an integral multiple of π/2.
Characteristics of a‐Si films prepared by compressed magnetic field (CMF)‐magnetron sputtering
Authors: Hata Tomonobu , Kamide Yukihiro , Nakagawa Shigeki , Hattori Kouji 
Published: July 2007

AbstractIraditionally, Ar gas has been used forring. However, when a hydrogenized amourphous film is formed by reactive sputtering the disturbance of the bonding network in Si by the incorporated Ar atoms and the collision of the highly energized Ar particles to the Si substrate cause a high density defects in the film.The compressed magnetic field magnetron sputerring system has been developed to minimize the damage to the substrate and to enable film deposition at low temperature. High‐quality a‐Si:H film has been formed by using He whose atomic radius is smaller than of Ar. In this paper, the characteris of the compressed magnetic field‐magneting sputtering system are described. The film is characterized by using the pressure of hydrogen as a parameter. over, the characteristics and thermoprotion of the film by He sputtering are computer with those of the film by Ar sputter.As a result: (1) in case where He was the film characteristics depended higly on the partial pressure of H2 when low (<1.0 mtorr). The best film was when the partial pressure of hydroling was 0.5 mtorr; and (2) the film by He harring did not show degradation by the treatment at temperatures up to 400°C.
Energy theory on discharges of E x B type devices
Authors: Tanizuka Noboru 
Published: July 2007

AbstractA systematic theory to interpret discharge phenomena generated in E x B structural discharge devices (magnetron type, PIG type, concentric quasi‐spherical type, and so forth) is developed by applying the classical magnetron theory to E x B structural systems. The transforming efficiency h, γ) from the electrostatic energy of a charged particle (mass m) in an electrode system (voltage between the electrodes VCA) to the discharge energy and the coefficient ε(η, r)/(JQVCA/r2) of the energy ε per unit time in unit volume of the discharge bulk are obtained where a device constant k = e (r2 B)2 gives the dimensionless quantity h = √m/k; γ(<1) is a ratio of the electrodes' radii, JQ is the current density at the inner electrode γr2, r2 is the outer‐electrode radius, the potential U2 is U2 = VCA/(1 ‐ r2), and B is the magnetic flux density.The discharge occurs under the condition h2 + r2 < 1. Because 1 ‐ η is consumed for heating electrodes (raising the temperature of a device), one may select the optimum condition of h and γ for η → 1 if possible. The coefficient of ε is advantageous for γ +1, but care must be taken because it has a maximum value with the parameter h. The energy ε is related to the density and the temperature of discharge products, and the purposes of the device use.As for experimental examples of the forementioned types of devices, considerations and comparisons with calculated results of h, γ η and ε are given.The theory presented in this paper is useful for designing such devices as ion sources for ion beam technology, and fundamental researches on cosmic plasmas and nuclear fusion plasmas and for interpreting discharge phenomena generated in these types of devices.
Effects of heat‐treatment on dielectric properties of anodized Al‐Ta double oxide layer thin‐film capacitors
Authors: Dobashi Tsuyoshi , Umezawa Toshiji , Sasaki Katsutaka 
Published: July 2007

AbstractThe effect of the heat‐treatment on the dielectric properties of capacitors with the structures of Al‐Ta2O5‐Al2O3‐Al and Al‐Al2O3‐Ta2O5‐Ta were investigated. The Ta and Al films were deposited by sputtering in the Ar‐N2 gas mixture (2.5% N2 in volume) and Ar gas, respectively. The layers of Ta and Al were anodized to form Ta2O5 and Al2O3. As the treatment temperature is increased up to 200°C, the improvements on tan δ and TCC were observed. However, when the capacitors were treated at 300°C, the loss characteristic of the Al‐Ta2O5‐Al2O3 type capacitor degraded. However, the Al‐Al2O3‐Ta2O5‐ type capacitor did not show any degradation and tan δ decreased to 0.0023. To discuss the difference in the losses between the two capacitors, the devices were investigated by Auger analysis. The loss degradation in the Al‐Ta2O5‐Al2O3‐Al type capacitor was related to the nonstoichiometric interface layer between the aluminum oxide and the base metal layers, while the decrease of the loss in the Al‐Al2O3‐Ta2O5‐Ta type capacitor was due to both the recovery of the stoichiometry in the interface between the tantalum oxide and the base metal and the decrease of the metallic aluminum atoms in the aluminum oxide which degraded the stoichiometry of the aluminum oxide layer.
InP metal‐insulator‐semiconductor field‐effect transistors using vacuum‐evaporated films
Authors: Takagi Shinichi , Sugano Takuo 
Published: July 2007

AbstractThe characteristic of the interface between InP and an insulator was investigated using an MIS structure on an InP substrate fabricated by using vacuum‐evaporated SiO or ZnS for the gate insulator and vacuum‐evaporated aluminum for the gate electrode. An interface state density of 5 × 1011 cm−2 eV−1 was obtained from the C ‐ V characteristic of the MIS diode fabricated on an n‐type InP. Annealing at a temperature between 100 and 200°C was effective in decreasing the hysteresis and the interface state density. InP MIS FET transistors were fabricated using vacuum‐evaporated SiO and ZnS films for the gate insulator, resulting in an excellent dc FET characteristic. The effective mobilities were as high as 3100 cm−2/V.s and 1400 cm−2/V.s when SiO was used on semiinsulating and p‐type InP substrates, respectively. When ZnS was used on a semiinsulating substrate, the effective mobility was 1800 cm−2/V.s.The mobility of the device was influenced strongly by the activation temperature of the ion‐implanted substrate. When the activation temperature was increased from 660°C to 700°C, the mobility decreased. This mobility decrease is considered to be due to Coulomb scattering in the channel.
Phase‐matched second harmonic generation of an Nd: YAG laser in a 2‐methyl‐4‐nitroaniline (MNA) single‐crystal thin‐film waveguide
Authors: Itoh Hiroshi , Hotta Kazushi , Takara Hidehiko , Sasaki Keisuke 
Published: July 2007

AbstractA single‐crystal thin‐film of 2‐methyl‐4‐nitroaniline (MNA), which is an organic compound with a very large optical nonlinearity was formed on a pyrex substrate. Using the structure as a waveguide, the phase‐matched second harmonic generation (SHG) of a YAG laser (wavelength 1.064 μm) was observed. The phase‐matching was achieved utilizing the TE mode phase‐dispersion of the guided wave. This is the first report where MNA thin‐film is used as a waveguide. The conversion efficiency for SHG is estimated as approximately 0.3 percent for the input power of 10 W, waveguide‐length of 2 mm and beam diameter of 0.2 mm.
Effect of compositionally grading on DC characteristics of A1GaAs heterojunction bipolar transistors
Authors: Takano Chiaki , Taira Kenichi , Kawai Hiroji , Arai Michio 
Published: July 2007

AbstractAn A1GaAs bipolar transistor which is expected to be a superhigh‐speed device for the future, was fabricated by using the MOCVD technique. The dependencies of the collector current, base current, and current gain on the vertical structure, especially, A1 compositionally grading in the emitter and base, were investigated. The effective barrier height between the emitter and base was evaluated from the temperature characteristic of the collector current. The base current was evaluated from the dependence on the n value and the size. The base current is due mainly to the surface recombination current and the recombination current in the neutral base layer. The reverse injection of holes from the base is negligible. The ratio of the base current which is due to the recombination in the neutral base layer to the collector current can be decreased by grading in the base. Finally, to improve the uniformity of the collector current, the emitter should be graded and the base should be formed of GaAs.
Transport analysis of a resonant‐tunneling hot electron transistor (RHET)
Authors: Ohnishi Hiroaki , Yokoyama Naoki , Shibatomi Akihiro 
Published: July 2007

AbstractResonant‐Tunneling Hot Electron Transistors (RHETs) are expected to be an ultra‐high speed and new‐functional device. In this paper the operating principles of RHETs are analyzed and the optimization of the device structure is discussed. For the analysis of the resonant tunneling barrier at the base‐emitter, a self‐consistent method using the Schrödinger and Poisson equations is adopted. To analyze the transport properties of hot electrons in the base, the Monte Carlo method is used. The transfer ratio and device transit time are investigated. Also, a comparison is made between the calculated and measured results.