bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of heat and compression treatment on magnetic and demagnetization properties of CoCr perpendicular magnetic recording media
Authors: Honda Yukio , Futamoto Masaaki , Yoshida Kazuetsu 
Published: July 2007

AbstractCoCr alloy thin films considered useful for perpendicular magnetic recording media and films deposited by vacuum evaporation and sputtering have been evaluated. In this study, a CoCr was vacuum‐deposited on Ge underlayers to prepare preferentially oriented films in the c‐axis direction. The influences of the thermal and pressure treatments on the magnetic properties were investigated. The influences of thermal and pressure treatments on the remanence magnetization where the magnetization was carried out in one direction normal to the film surface and the perpendicular magnetic recording were also investigated. As a result, it was found that the thermal treatment at a temperature higher than the deposition temperature reduced the saturation magnetization and increased the perpendicular coercivity and perpendicular magnetic aniso‐tropy. The amount of these changes was greater for the films deposited at lower substrate temperature which had smaller coercivity values. The changes in the magnetic properties were thought to be due to the Cr diffusion during heat treatment. On the other hand, during the pressure treatment, no change in the magnetic properties was observed. The decrease of magnetization due to the thermal treatment was smaller when a film was recorded perpendicularly magnetic than when it was magnetized in one direction perpendicular to the film surface. The decrease of the magnetization was smaller as the recording density increased. In the pressure treatment, the remanence magnetization where magnetization occurred in one direction decreased monotonically as the applied pressure increased. On the other hand, when the perpendicular magnetic recording was carried out on films, less decrease in magnetization was observed.
Effect of Mn‐codeposition on electroless Co alloy magnetic recording films
Authors: Matsuda Hitoshi , Takano Osamu , Furusawa Satoshi 
Published: July 2007

AbstractThis paper describes the fabrication technique of a longitudinal magnetic recording film by the electroless plating method. When 1 percent Mn is codeposited in Co‐P film, coercivity of 12.0 × 104 A/m (1500 Oe) could be achieved if the film is thicker than 0.05 μm. Furthermore, this high coercivity is also observed in a film as thick as 10 μm. The high coercivity is thought to be due to Mn(OH) formed in the deposition bath and which segregates at the grain boundaries of the film. Moreover, not only does it magnetically isolate each grain but also inhibits the lateral growth of grains during film growth.
Light‐induced degradation characteristics of MIS junction using hydrogenated amorphous silicon
Authors: Kawai Shintaro , Hatanaka Yoshinori 
Published: July 2007

AbstractIn an MIS device composed of a transparent electrode, amorphous silicon nitride insulator, and hydrogenated amorphous silicon, optically induced degradation in the optical current characteristic was observed after optical irradiation at an intensity of 2000 1x. This degradation was strongly dependent on the material used for the transparent electrode. The highest degradation was observed when ITO was used. However, when a Pt electrode was used, no degradation was observed even after optical irradiation for 100 hr. The degradation was lowered by coating the surface of the ITO electrode with a thin Pt film.A change in the optical current due to the difference in the optical bandgap of the silicon nitride used as a thin insulating layer was not observed. However, as the optical bandgap of the silicon nitride increased, the threshold voltage for the I‐V characteristic under illumination tended to shift to the higher voltage.It was concluded from the experimental result that the characteristics of an MIS device are strongly dependent on the transparent electrode. Therefore, special care must be taken in the fabrication of the transparent electrode, and coating the electrode with a thin Pt film is an effective way to stabilize the device. The amorphous silicon nitride film should be of high quality and as thin as possible to minimize the optically induced degradation.
Self‐injection locked gunn oscillator using nonradiative dielectric waveguide
Authors: Takada Masayuki , Yoneyama Tsukasa 
Published: July 2007

AbstractA Gunn oscillator is developed using a nonradiative dielectric waveguide which is employed in millimeter‐wave integrated circuits. First, the structure and operation mechanism of the oscillator are described. The test of the oscillating properties shows the possibility of determining its frequency, and the maximum output power can be compared to that of the waveguide oscillators. Then a self‐injection locked Gunn oscillator using a dielectric resonator is developed for frequency stability and noise reduction. It is found that a TEQ2δ mode high‐dielectric ceramic resonator gives the best results when installed, and the oscillator was proved to be practical by measured performances which show the pushing figure and temperature coefficient as 1 MHz/V and ‐5 ppm/°C, respectively.
Finite element analysis of discontiuities in nonradiative dielectric waveguide
Authors: Endo Yoshinori , Yoneyama Tsukasa 
Published: July 2007

AbstractDiscontinuity problems in the nonradiative dielectric waveguide are treated by the finite element technique. Both computing time and memory can be reduced significantly by introducing infinite elements which take into account the evanescent nature of the fields outside the dielectric strip. The hybrid nature of the fields is also taken into account to improve numerical accuracy when the analysis expression for the far fields and the FEM solution for the near fields of discontinuities are matched. Various structures, such as gaps, high‐permittivity dielectric sheet inserts, bandpass filters and even T‐junctions have been analyzed. Some results are confirmed by experimental value.
The law of total reflection in geometrical optics based on wave normals
Authors: Hashimoto Masahiro 
Published: July 2007

AbstractA geometrical law describing the reflection of wavefronts and wave normals of non‐spherical waves at interfaces is presented. Generally speaking, the angle of incidence and the angle of reflection are different, and the difference is a function of the configuration of the wavefront of the incident wave. With regard to plane wave reflection, the present results are in agreement with conventional laws.
Properties of a‐Si1‐xCx:H protective surface‐layer for electrophotographic photoreceptor
Authors: Ohno Toshiyuki , Ishikawa Fuminori , Tamahashi Kunihiro 
Published: July 2007

AbstractFor an application for electrophotographic photoreceptors, a‐Si1‐xCx:H film was prepared by a plasma CVD method with C2H4 or CH4 as a carbon source, and the dependence of water wettability on the source gas and carbon concentration as well as the dependence of the contact angle with water on the corona exposure has been examined. Surface reactants formed after the corona exposure have also been examined. As a result, it was found that the wettability of the a‐Si1‐xCx:H film decreases with the carbon concentration independent of the source gas. However, corona exposure for one hour increased the water wettability. This trend was found to be independent of the carbon concentration in the film. As a result of the infrared absorption spectrum, this was attributed to the formation of Si‐Ox bond (x = 1.7 ‐ 2.0) by corona exposure.
Dual‐frequency (40/100 GHz) SIS receiver for nobeyama millimeter‐wave array
Authors: Yamamoto Masayuki , Yamaji Katsutoshi , Watazawa Keiichi , Inatani Junji , Kawabe Ryohei , Kasuga Takashi 
Published: July 2007

AbstractThe authors developed a dual‐frequency (40/100 GHz) SIS receiver with SIS quasi‐particle tunneling junction element as the mixer, for use in the millimeter‐wave array at Nobeyama Radio Observatory, National Astronomical Observatory. The SIS element used is an array composed of four series‐connected Nb/Al‐AlOx/Nb junctions. The receiver is refrigerated to 4.3 K by a closed‐cycle He refrigerator. The receiver realized a very low receiver noise temperature for a wideband, such as 50 to 80 K for 43 to 49 GHz, and 60 to 100 K for 86 to 115 GHz. A wide dynamic range is also realized. At 40 Ghz, the saturation noise temperature is 2000 to 3000 K, compared with the wideband noise. These results indicate that the SIS array element can effectively improve the mixer saturation level without degrading the receiver performance.
A realization of a wide‐band second‐generation current conveyor by using complementary transistors
Authors: Horita Motoshi , Kitajima Yasuhiko , Ma Zhiqiang , Yamamoto Gaishi 
Published: July 2007

AbstractAlthough a number of realization circuits for second‐generation current conveyors (CCII) and their applications to active RC networks have been reported, the bandwidth of CCII itself is not sufficient. It is pointed out that one of the causes of degradation of the RF characteristics of the CCII using the complementary transistors is the effect of signal current flow through the collector capacitance Cc. A method is described also for broadband operations by compensating this effect actively. In practice, a transistor with the gain bandwidth product fT of 100 MHz is used for construction of a positive‐type CCII. The voltage transfer factor and the impedance looking into the X terminal have improved with or without compensation while the current transfer factor has improved with compensation so that those are almost ideal characteristics within the measurement up to 10 MHz. The magnitudes of the impedances looking into the Y and Z terminals decreased beyond about 100 kHz due to the effect of the stray capacitance of each terminal and fT. However, there is improvement as the magnitude is larger by an order than the uncompensated case. As an application, the compensated positive‐type CCII is used for construction of a biquad low‐pass filter with the pole frequency of about 3 MHz. The operation was satisfactory.
Planar integration of laser‐recrystallized SOI‐Tr's fabricated by lateral seeding process and bulk‐Tr's and its application to fabrication of a solid‐state image sensor
Authors: Fujii Eiji , Senda Kohji , Emoto Fumiaki , Nakamura Akira , Uemoto Yasuhiro , Kano Gota 
Published: July 2007

AbstractTo realize functions which cannot be achieved by conventional integrated circuits composed of bulk transistors (bulk‐Tr), part of an integrated circuit was formed by laser‐recrystallized SOI transistors (SOI‐Tr) using the lateral seeding process. The uniqueness of this structure is that the bulk‐Tr's and SOI‐Tr's are formed in the same plane. To realize this planar structure, the necessary basic technology was developed and bulk‐Tr's and SOI‐Tr's were formed in the same plane to test the structure. The characteristics of the transistors were compatible to those of transistors formed by conventional MOS processes. For the application of this structure to integrated circuits, a solid‐state image sensor was fabricated where the driver circuits were formed by the bulk‐Tr's and the read‐out of the picture elements was carried out by using the SOI‐Tr's. As a result, a high‐quality image was obtained and the smear noise caused by photoleakage current was suppressed.
Improvement of asymmetrical characteristics in submicron CMOS devices
Authors: Yabu Toshiki , Kurimoto Kazumi , Yamauchi Hiroyuki , Fukumoto Masanori , Ohzone Takashi 
Published: July 2007

AbstractIn the substrate current characteristics and the drain current characteristics in a submicron nMOSFET with an LDD structure, the problem of asymmetry caused by ion implantation occurs if the measurement is done with the source and drain interchanged. It is found also that significant asymmetry appears in the subthreshold current characteristics (threshold voltage) in a submicron pMOSFET with EPS (efficient punchthrough stops). By introducing the four‐step implantation method as a technique to form LDD and EPS regions, an attempt was made to improve asymmetry. By this method, symmetric electrical characteristics are obtained without changing the conventional process and without reducing the throughput. Further, the unbalance of the threshold voltages between the pair transistors was measured because they have the greatest effect on the sensitivity of the sense amplifier important in the VLSIDRAM. It was found that the four‐step implantation method is extremely effective for suppressing the asymmetry without changing the circuit design.
Basic study on Si‐HBT using plasma‐deposited μc‐Si for heteroemitter
Authors: Sasaki Kimihiro , Fukazawa Takeshi , Furukawa Seijiro 
Published: July 2007

AbstractThis paper describes the crystallinity, electric properties and bandgap of Si films deposited on a single‐crystalline substrate by plasma CVD, and the application of this film to the heteroemitter of an Si‐HBT.The plasma CVD Si film is grown epitaxially near the interface with a single‐crystalline substrate (in this experiment, the thickness was less than 10 nm). However, as the film thickness increases, the crystallinity of the film degrades and the film eventually becomes μc‐Si. The crystallinity depends on the surface orientation of the substrate. The epitaxial growth occurs more easily on a (100) surface than on a (111) surface. The film resistivity is dependent on the degree of the epitaxy and is lower in a film grown on a (100) substrate than on a (111) substrate, and lower near the interface than the surface.The bandgap estimated from the optical absorption characteristic is 1.34 eV. This value is smaller than that of a film deposited on a glass substrate but is larger than that of single‐crystalline Si. Therefore, it is expected that this film can be used to form a wide bandgap heteroemitter structure. In the Si‐HBT formed by using this film for the emitter, the current gain was as high as 480. When a polycrystalline film was used, the current gain was only 15. Therefore, the high current gain of a μc‐Si heteroemitter transistor is not due to the oxide layer at the interface but to the wide bandgap heteroemitter.
Surface‐emitting lasers
Authors: Iga Kenichi , Koyama Fumio , Kinoshita Susumu 
Published: July 2007

AbstractSurface‐emitting lasers which emit laser beams in the direction normal to the substrate are attractive devices in applications for two‐dimensional laser arrays and parallel optical communications.Recently, horizontal cavity and bent cavity devices have been investigated. Among such devices, the microvertical cavity surface‐emitting laser, which has a cavity normal to the substrate, has a cavity only several times longer than the wavelength. The length of the cavity in the lateral direction also can be reduced to a size several times longer than the wavelength. Therefore, by using this type of laser, superior longitudinal mode selection, low‐noise operation and low threshold current are expected.Furthermore, a high‐density two‐dimensional array can easily be manufactured with this device and its application to parallel optical communication is expected. This paper will describe our vertical‐cavity,surface‐emitting laser, as well as our view of surface‐emitting lasers now and in the future.
An evaluation of shield effects in semicoaxial wiring board
Authors: Fukutomi Naoki , Nakamura Hidehiro , Yoshida Norinobu , Fukai Ichiro 
Published: July 2007

AbstractWith the advancement of miniaturization and performance of electronic equipment, high‐density mounting technology has become important. Specifically, as the density of wiring board and the frequency of operation are increased, crosstalks can increase generation echos and cause degradation of the reliability of the equipment. Hence, it is desirable to reduce the equipment noise. A semicoaxial wiring structure is introduced to reduce the crosstalk in a multiwire board. The spatial network method is used for the electromagnetic field analysis to determine its effect. In the analysis, a rectangular model and a cylindrical model are introduced and the time responses of the electromagnetic field are observed qualitatively. Further, the propagation delay and the degree of coupling between the parallel wires are studied quantitatively as the basic electrical characteristics of the wiring board. It is found that there is no significant difference in the analysis of the two models. It is seen that the cylindrical model which is closer to reality can be simplified by a rectangular model. The relationship between the semicoaxial wiring structure and the degree of coupling is such that the shielding effect depends on the location of the shielding conductor and the degree of coupling decreases substantially by wrapping the structure more deeply than the center of the wire.
Optical filter using a fabry–perot type semiconductor laser amplifier
Authors: Koga Masafumi , Kikushima Koji , Nawata Kiyoshi 
Published: July 2007

AbstractThis paper discusses the filtering function used in channel selection, due to selective amplification characteristics of the longitudinal mode of resonant‐type semiconductor laser amplifiers (FP‐SLA). The bandwidth of filter passband B and the crosstalk from unselected channels X which depend on the facet reflectivity R and signal gain G FP‐SLA are determined theoretically. From calculations of the number of channels N, for the crosstalk X to be less than −10 dB, the following results are obtained: 1 if R is reduced to below 5 percent, to obtain bandwidths wider than 10 GHz which can be used in selection of wide‐spectrum directly modulated signals, N must be limited to 8; 2 if R = 32 percent, G = 30 dB, then B is narrowed to less than 1 GHz which permits N to be increased up to 20. Finally, using the light signals of a two‐channel multiplexed system directly modulated at 400 Mbit/s, a transmission experiment is carried out in which sufficiently good optical filtration characteristics are achieved using a an FP‐SLA with R = 0.7 percent.
Defect characterization and gettering effect in excimer laser gettering
Authors: Sakai Akira , Ohshita Yoshio , Ishitani Akihiko , Takemura Kazumi , Toyokawa Fumitoshi , Mikami Masao 
Published: July 2007

AbstractThe mechanism and effect of a new extrinsic gettering method utilizing excimer laser irradiation called excimer laser gettering (ELG) was examined by transmission electron microscopy (TEM) observation and measurements of the electric properties of metal‐oxide‐semiconductor (MOS) capacitors. By means of TEM, stacking fault tetrahedra and V‐shaped dislocations were found in the irradiated regions of Si wafers and these defects were proved to be thermally stable. Dielectric breakdown failure of SiO2 films and generation lifetime of minority carriers were improved remarkably by ELG. It was confirmed that the gettering effect of ELG has higher temperature persistence than sandblasting methods used heretofore.
Wide dynamic range photodiode arrays sensitive and stable to ultraviolet radiation
Authors: Yazawa Yoshiaki , Katoh Iwao , Sonobe Sigeru 
Published: July 2007

AbstractA photodiode array with 512 elements was fabricated for analysis and measurement, and its characteristics were evaluated. By placing a DMOS‐type capacitor in the separation area between the photodiodes, their capacitance was as high as 13.5 pF. The dynamic range was as high as 1000 under normal operating conditions.The photodiode was sensitive to wavelengths ranging from 200 to 1000 nm. The initial sensitivity to the wavelength of 254 nm was over 0.1 A/W. The ultraviolet ray dependence of the device characteristic was also investigated. It was found that even after the photodiode was exposed to a high‐intensity ultraviolet ray corresponding to exposure for 10,000 hours under standard conditions, the sensitivity of the photodiode to ultraviolet was higher than 0.06 A/W.
Theoretical analysis and fundamental characteristics of triplate spiral inductors
Authors: Yabuki Hiroyuki , Makimoto Mitsuo 
Published: July 2007

AbstractThis paper presents a theoretical analysis method and basic characteristics of triplate spiral inductors. The analysis is based on low‐frequency band transmission line theory from which three different transmission line circuits are used to model the inductor; after obtaining the circuit impedances for different potential profiles, we consider the high‐frequency problem using a model in which the interline electric field couplings are simulated as lumped capacitances. Based on these techniques, it is possible to investigate the basic properties such as the inductances, self‐resonant frequencies and losses.The triplate inductors can be used as three‐dimensional hybrid IC elements in the UHF band (0.3 – 3 GHz) such as broadband matching circuits, various filters, and decoupling circuit for the power supply line.
Polarization state and gain of lights interacting through stimulated Raman scattering in single‐mode optical fibers
Authors: Seikai Shigeyuki , Takahashi Masaki 
Published: July 2007

AbstractThe polarization states and gain of the signal and pump lights in an optical amplifier using stimulated Raman scattering in an optical fiber were investigated. Taking into account circular birefringence caused by fiber twist, a coupling equation for the signal and pump lights was obtained. It was assumed that the fiber had a circular core and was uniform in the longitudinal direction and that the field distribution of the dominant mode was Gaussian.With the aid of numerical calculation of the coupling equation by the Runge‐Kutta method, the propagation properties of the polarization states and gains of the signal and pump lights were investigated. When the fiber was not twisted, the propagation property depended on the polarization state of incident light. However, except when the incident light was in a special polarization state, the signal light generally came close to linearly polarized light in the direction of the major axis of the elliptically polarized incident pump light.The difference between the signal optical gains of linear and circular polarization was 3 dB at most. When the twist rate in a fiber was over 1 turn/m, the signal light polarization state was almost unchanged during propagation and the optical gain was stable for various polarization states of the incident pump light.
Characteristics of superconducting Bi‐Sr‐Ca‐Cu‐O thin films prepared by a multilayer evaporation method
Authors: Honda Yukio , Tsukamoto Akira , Futamoto Masaaki , Takagi Kazumasa 
Published: July 2007

AbstractThis paper describes the production of Bi‐Sr‐Ca‐Cu‐O superconducting films by oxidizing multilayer films composed of Bi2O3SrO/Cu/Ca deposited by vacuum evaporation. Heat‐treatment conditions for oxidizing and influences of layer thickness on formation of the high Tc phase are studied. To mix each element well, it is important to melt the multilayer film partially at the initial stage of heat treatment. Furthermore, it is a key point in preventing the formation of the Ca‐Cu oxide.The thickness of a unit layer composed of Bi2O3/SrO/Cu/Ca is varied from 20 nm to 86 nm. By thinning the unit layer, the volume fraction of the high Tc phase is increased; Tc of 98 K is achieved when the unit layer thickness is 21.1 nm.