bluuebunny/crossref_metadata_2025 huggingface dataset:
A solid electrolytic paper battery containing electroconductive polymers
Authors: Osawa Toshiyuki , Kimura Okitoshi , Kabata Toshiyuki , Samura Tetsuya , Yoshino Katsumi
Published: July 2007

This paper describes a solid paper rechargeable battery using an electrolytically polymerized polyaniline film as the electrode and nonaqueous electrolyte gel with high ionic conductivity as the solid polymer electrolyte.

A high‐strength fibril polyaniline film with a tensile strength of 5 kgf/cm2 was formed by electrolytic polymerization in tetrafluoro‐boric acid. It was found that the film had an excellent oxidation‐reduction characteristic in the solid polymer electrolyte. In addition, by bridging a highly concentrated nonaqueous electrolyte in monomer, the ionic conductivity of the solid polymer electrolyte was comparable with that of liquid electrolyte.

Since the solid polymer electrolyte was fabricated using a solution with low viscosity, a solid paper lithium rechargeable battery with a highly efficient discharging property was realized by combining a polyaniline film.
Properties of GaAs1 ‐ xPx epitaxial films prepared by ion beam sputter deposition
Authors: Takaishi Yoshihiro , Itoh Tadatugu
Published: July 2007

Many works on heteroepitaxial growth of III—V compound semiconductors on an Si substrate have been reported. However, many problems must be solved. In this study, GaAs1 ‐ xPx heteroepitaxial growth on Si and GaAs substrates at 250°C was carried out using the ion beam sputter‐deposition method. The dependencies of crystallinity and electrical properties of deposited films on x were investigated.

The film composition was investigated by evaluating the core level spectra for As‐3d and P—2p levels in X‐ray photoelectron spectroscopy. In this evaluation, the composition was independent of the kind of substrate and film crystallinity.

When a polycrystalline GaAs target was sputtered by Xe ion beam, the deposited film was neither single‐crystalline nor stoichiometric. When a mixture of Xe and PH3 ion beams was used, the deposited film was stoichiometric and RBS revealed that the film had excellent crystallinity. When a film was deposited on a GaAs substrate, the carrier mobility was higher than when it was deposited on Si.
Three‐dimensional memory LSI with optical interconnections
Authors: Koyanagi Mitsumasa , Takata Hirokazu , Okano Hiroshi , Yokoyama Shin
Published: July 2007

As devices are miniaturized and device operation speed increases by the progress of fine fabrication technology, the problems associated with interconnections such as interconnect delay and crosstalk are becoming important. Therefore, an optical connection as a new interconnect technique to solve these interconnection related problems is becoming noticed. On the other hand, three‐dimensional LSIs are again becoming noticed as an LSI to overcome the limitations of high integration and to incorporate new functions such as parallel processing function. Consequently, this paper examines the possibility of LSI with new function surpassing the present LSIs by combining the optical interconnection and three‐dimensional LSIs by combining the optical interconnection and three‐dimensional LSI. As an example of this kind of LSI, a three‐dimensional optically coupled common memory is described and the performance improvements are specifically shown by combining the optical interconnection and three‐dimensional LSI.
Single‐mode selection in pulsed lasers by injection seeding
Authors: Taira Takunori , Ogishi Hisataka , Kobayashi Takao
Published: July 2007

A high‐power pulsed solid‐state laser for single‐mode oscillation is considered to be an important device in the new coherent optoelectronic fields such as super‐high‐resolution optics and heterodyne lidar. The injection seeding method has been utilized for single‐mode operation of high‐power Q‐switched lasers but the analyses of the basic characteristics and detailed experimental evaluation have not been carried out.

In this paper, the conditions for single‐mode oscillation are analyzed using the multimode oscillation model and basic laser equations. Then the seeding characteristics are investigated using a laser diode (LD) pumped tunable wavelength single‐mode Nd : YVO4 microchip laser for the master laser and a pulsed Q‐switched Nd : YAG laser for the slave laser. As a result, it was found that single‐mode operation could be realized by the extremely low power of 0.9 μW which was close to the theoretical limit.

In about 140 μm injection, the detuning width was 282 MHz which was close to the longitudinal mode separation. A seeding bandwidth of 71 GHz, which is almost half the fluorescence spectrum width of Nd : YAG, was realized.
Synthesis of biquadratic filters from current conveyors
Authors: Ikeda Katsuji , Tomita Yasushi
Published: July 2007

This paper describes a circuit configuration for a biquad filter which utilizes the second‐generation current conveyors (CC II) and is capable of synthesizing an arbitrary second‐order transfer function.

The circuit is composed of a subblock circuit with two positive CC IIs and a differential input circuit with two positive CC IIs.

The subblock circuit realizes a lowpass, high‐pass, and bandpass filter. Combining this with the differential input circuit produces an all‐pass and notch filter.

Each filter has a high input impedance because its input is the Y terminal of the CC II and can be cascaded without a buffer. The quality factorQof the filter is determined by a ratio of passive elements, and its sensitivity to the passive element values is less than 0.5. These characteristics make the filters suitable for monolithic IC implementations. The effects of CC IIs voltage error ϵvand current error ϵion the filter characteristics were studied. It was found that the center frequency ωois independent of these errors,Qis affected only by ϵi, and the gain factor is a function of both ϵvand ϵi. Each filter was prototyped and was verified to operate as predicted.
Eigenstates of quantum wire structures with quasi‐bound geometry
Authors: Tsuji Yasuhidé , Hayata Kazuya , Koshiba Masanori
Published: July 2007

The eigenstate calculation of quantum‐wire mesoscopic structures with quasi‐bound geometry is reported. In this geometry, electron wave packets are confined quantum mechanically into an effective potential cavity created by the crossing of quantum wells.

First, a variety of quasi‐bound quantum wire structures is presented. Subsequently, the eigenenergies and the eigenfunctions are analyzed numerically by using a two‐dimensional finite element method (2‐D FEM). In this analysis, effects due to the finiteness of the barrier height are studied in contrast to earlier simple models where the height is assumed to be infinite.

Structural dependencies of the eigenstates show evidence of the critical parity selectivity for wave functions trapped in the quasi‐bound quantum wire system. A comparative study of analysis methods is made as well. Comparison of the results obtained by the 2‐D FEM with those by the weighted potential method shows the limitation of the latter reproduced approach to the present problem.
Discrete frequency sweeping of a semiconductor laser by temperature change and electrical feedback
Authors: Yoshizawa Akio , Iwasaki Takashi
Published: July 2007

In a constant interval multifrequency measurement to evaluate optical device characteristics, considering that a constant time is required for the measurement at each frequency, a sweeping method that maintains the frequency during the measurement is desirable. Although this stepwise frequency sweeping can be achieved by changing the injection current of the semiconductor laser, the possible sweep frequency range is much wider for the temperature change than for the current change.

In this paper, noting this wideband sweeping range by the temperature change, two frequency sweeping methods are proposed. In these methods, the frequency changes stepwise for the temperature change proportional to the time that is easy to realize, and are verified and compared experimentally. In this method, a part of the laser light is incident on the Fabry‐Perot resonator with the temperature change, and the transmitted light signal or its differential signal is fed back into the injection current. As a result, the feedback signal corresponding to the resonant characteristics controls the shift of the resonance frequency by the temperature change in the neighborhood of the resonance frequency, realizing the frequency sweep that changes stepwise with the spacing equal to the free spectral range of the Fabry‐Perot resonator.
Analysis of lossy dielectric gratings using pseudo‐periodic green's function
Authors: Minami Kouji , Yamakita Jiro , Sawa Shinnosuke
Published: July 2007

Differential equation methods often are used for the analysis of the waves scattered by a dielectric grating. It is known that accurate numerical solutions can be obtained if the number of expansion terms of the spatial harmonics is increased. However, when the differential equation method is applied to a dielectric grating with an extremely large permittivity, the convergence speed of the solution becomes excessively slow in the TM wave analysis. Because of the increase of the computation time and the memory capacity, an analysis based on the differential equation method becomes difficult in practice.

In this paper, it is shown that a boundary element method using Green's function satisfying the periodic condition is effective for the analysis. By introduction of pseudo‐periodic Green's function, the definition region for the integral equation is limited to the grating surface. In comparison to the boundary element method using the Hankel function, the number of linear equations is reduced. By means of numerical examples, it is shown that the convergence speed of the solution by the present method is faster and the computation time is significantly shorter than the solution by the differential equation method even in the TM wave analysis of a dielectric grating with a large loss.
Three‐dimensional finite element solutions of electron waveguide discontinuities
Authors: Gotoh Hitoshi , Koshiba Masanori
Published: July 2007

A numerical approach based on the finite element method using tetrahedral elements is proposed for the three‐dimensional discontinuity in electron waveguides. A three‐dimensional finite element method is applied for a region containing a discontinuity with an arbitrary shape. The uniform waveguide region connected to the discontinuity is treated analytically. The reflection probability and transmission probability are calculated, in addition to the current density, by combining the finite element method and the analytical solution. The transmission characteristics of a rectangular cavity between two electron waveguides are examined. It is found that the transmission probability of the three‐dimensional structure is much different from that of the two‐dimensional one.
Finite element analysis of open‐type waveguides with homogeneous cladding by the use of multipole expansion
Authors: Ise Tomoyuki , Maruta Akihiro , Matsuhara Masanori
Published: July 2007

Open‐type waveguides with homogeneous cladding can be analyzed by the finite element method (FEM) with the multipole expansion method. In this paper, we propose a new connection method in which the fields described by the FEM and by the multipole expansion are combined at the connection boundary between the finìte inner region and the infinite outer region by using Galerkin method. By means of this method, we can analyze open‐type waveguides with higher accuracy and less amount of calculation than conventional FEM. In addition, there is no difficulty arising from spurious mode and no restriction between the number of the basis functions of the FEM and that of the multipole expansion functions on the connection boundary. The final matrix equation is symmetric. The validity and usefulness of the method has been demonstrated in the example of a rectangular dielectric waveguide and an elliptical fiber.
Fixed pattern noise from charge transfer loss in CCD imager
Authors: Ohkubo Yoshio , Ohmae Masanori , Ishikawa Kiyotsugu
Published: July 2007

It has been analyzed theoretically and verified experimentally that fixed pattern noise (FPN) is generated by the charge transfer loss when the charge in the CCD imager device generated by photoelectric conversion is imaged with a charge partitioning mode. This is done by removing the unnecessary nonsignal charge and reading out the signal charge. The result shows that the transfer loss due to the removal must be less than 10−4 to achieve even an ordinary picture quality with signal‐to‐noise (SN) ratio of 60 dB when the signal in the charge partitioning mode is one‐tenth the total charge. Furthermore, for a high‐quality image with SN ratio above 70 dB, the transfer loss in reading two kinds of charge must be less than 10−5 which is almost a perfect charge transfer.
Comparison of some characteristics of contact resistances on four kinds of Ag‐Pd alloy contacts with frequent switching of a 30V, 10A DC resistive circuit
Authors: Kubono Takayoshi
Published: July 2007

Twenty‐four pairs of respective Ag, AgPd70/30, AgPd40/60, and Pd contacts are mounted on 24 miniature relays as pairs of electrical contact and switched the 30V, 10A DC resistive circuit on and off 100,000 times with the 1‐s closing period and 2‐s opening period. At each closing period, the contact resistance was measured with 10‐A circuit current.

For all the materials, the histograms of the contact resistance averaged over 24 contact pairs from the start of opening/closing operations to 100 operations are clustered at approximately one location. The relation of the average contact resistance value among the four materials is the same as the relation of the resistivity and hardness. Therefore, the contact resistance at the initial stage of opening/closing operations is attributed to constriction resistance.

For the case of Ag and Pd samples, the average contact resistance during the 100,000 operations depends little on the number of operations. Also, it is approximately the same as the average contact resistance during the initial 100 opening/closing operations. However, for the AgPd30% sample, the variation width increases with the switching operations. This is attributed to the fact that a selective evaporation of Ag from the contact surface during the arc discharge occurs and the alloy composition at the true contact surface changes repeatedly for each switching, with a resultant increase in variation of the average contact resistance.
Silicon surface nitrification using hydrogen and ammonia by hybrid excitation
Authors: Yamamoto Shigeichi , Migitaka Masatoshi
Published: July 2007

A hybrid‐excitation technique using plasma excitation and photoexcitation in chemical vapor phase reaction has been developed. Using this technique, the silicon surface was nitrified in a mixture of ammonia (NH3) and hydrogen (H2) gases. First, a (100) Si substrate heated at 180°C was illuminated by ultraviolet ray (wavelengths: 184.9 nm and 253.7 nm) under NH3 atmosphere. At the same time, hydrogen radicals generated by decomposition of H2 gas in an RF (13.56 MHZ) inductive discharge tube were supplied to the substrate. Auger analysis indicated that the (100) Si surface up to about 1 nm in depth was nitrified and that the hybrid excitation was based on the synergy effect of photoexcitation and hydrogen radical excitation.

Next, staggered‐structure thin‐film transistors were fabricated using amorphous Si whose surfaces nitrified by the foregoing method and the conventional plasma excitation method. It was found that when the hybrid‐excitation method was used, the field effect mobility was highest. In the gas analysis of hydrogen radical excitation, the presence of hydrazine was confirmed. Using this observation, the direct nitrification mechanism in the hybrid excitation was assumed.
A theoretical study of the I‐V characteristic distribution of polysilicon TFTs
Authors: Shinohara Toshiro , Tarui Yasuo
Published: July 2007

A method to calculate the current‐voltage characteristics and its distribution of a polysilicon thin‐film transistor as a function of grain size has been developed. The simulation was based on a model for a potential distribution in each grain and the grain size distribution in a channel. The grain sizes (both observed and assumed) were used to set a grain size distribution in a channel, leading to determination of the number of grains and their location in the channel.

The thermionic emission by taking into account the modulation of a grain potential barrier due to a gate‐drain electric field was calculated, and then the current‐voltage characteristics were determined by a self‐consistency method. Applying this method to a large grain polysilicon thin‐film transistor grown by a solid‐phase growth method, the static characteristic and its variation could be simulated successfully by having only two adjustable parameters of interface trap density and grain boundary trap density. Based on the present method, one can obtain a grain size distribution necessary to obtain desirable electric characteristics and thus can have a guideline for a process development.
Development of technologies for 2‐Gb/in2 areal density recording
Authors: Futamoto Masaaki , Kugiya Fumio
Published: July 2007

Hard disk technologies to realize 2‐Gb/in2 magnetic recording have been developed. An areal density is determined by a combination of a linear density and a track density.

In this newly developed recording scheme a track density has been increased to 17 kTPI, equivalent to a level in an optical recording. A flying height is 0.055 m̈m and a longitudinal recording method has been employed. Several new technologies including a narrow‐track composite magnetic head, a low‐noise longitudinal bilayer magnetic medium, high‐sensitive position detection scheme using a semiconductor laser, and accurate positioning mechanics using a dual‐stage actuator have been developed. These technologies are combined into a 3.5‐inch rigid disk drive system. An ultrahigh‐density recording of 2‐GB/in2, which is 10 to 20 times larger compared to a current density, has been confirmed to be possible in combination with a signal processing technology which can cope with a deterioration in the reproduced signal‐to‐noise ratio (SNR).
Diode decoder circuits for ultrahigh‐speed memory
Authors: Ohhata Ken'Ichi , Homma Noriyuki , Kanetani Kazuo , Nambu Hiroaki , Yamaguchi Kunihiko
Published: July 2007

Diode decoders are often used in ultrahigh‐speed memory. The AND gate in this type of decoder consists of several diodes and the output voltage of the decoder varies depending on the number of conducting diodes. Although this variation in the output level is an important problem, it has not yet been studied in detail. This paper describes the mechanism of this effect and shows how it affects the performance of the decoder. The parasitic capacitance of the output node, the deviation of the output voltage, and the operating speed are compared for three kinds of diode decoders: a downward diode decoder, an upward diode decoder, and Schottky barrier diode (SBD) decoder, using 0.8‐μm SICOS (sidewall base contact structure) technology. It is shown that the upward diode decoder provides the highest performance. This high performance is demonstrated using the upward diode detector in a 64‐kb RAM.
Use of the faraday effect for frequency stabilization and control of a semiconductor laser
Authors: Ueno Takashi , Rikukawa Hitoshi , Nakazawa Takao , Sato Takashi , Shimba Minoru
Published: July 2007

To date, frequency stabilization methods for semiconductor lasers mainly use the absorption line of an atom or molecule to modulate the frequency of laser light slightly so as to obtain a control signal. As a result, an oscillation bandwidth broadening will appear and the stabilization point will be restrained at the center frequency of the absorption line. This paper reports a frequency stabilization method using a magneto‐optical effect, the Faraday effect of an atomic absorption line, instead of direct modulation of the oscillation frequency. This stabilization method made it possible to control the stabilization point frequency by changing the dc magnetic field. With an Rb absorption line as the frequency reference, the controlled frequency range was about 1.5 GHz, which is wider than the Doppler width of the Rb absorption line at room temperature. The experimental results were consistent with the theoretical analysis.
Recording characteristics of perpendicular magnetic recording medium using a stretched‐disk interface
Authors: Uchiyama Hiroshi , Honda Naoki , Oyanagi Eiki , Kawano Norikazu , Urakawa Yoshiyuki
Published: July 2007

The FM and digital recording performance of a stretched disk system with a good interface between a perpendicular magnetic recording medium and an MIG‐type ring head has been examined. Little evidence of the low‐frequency enhancement and high‐frequency suppression effect has been found in a short wavelength FM recording. No reversal noise was detected at a carrier wavelength of 0.3 μm in a short wavelength static image recording. However, a harmonics distortion and a cross‐modulation distortion were found to be significant and are believed to be due to a sharp transition of the magnetization direction of the medium, which is not suitable for two‐signal multiplex recording.

On the other hand, the error rate of digital recording is found to depend on signal‐to‐noise ratio (SNR) for a longer wavelength and a peak shift pattern for a short wavelength recording. The error rate better than 10−4 was obtained by using PRIV coding at 0.88 μm2/bit (Tw = 5 μm, λ = 0.35 μm). This result demonstrates the applicability to a high‐density recording. By improving a frequency response of a head and medium and by optimizing further pulse slimming, the wavelength limitation for error rate due to a peak pattern shift can be improved more.
High‐density magnetic tape recording by a nontracking method
Authors: Himeno Takuji , Tanaka Masato , Katoku Takashi , Matsumoto Kissei , Tamura Masafumi , Min‐Jae Han , Sasaki Toshikazu , Ito Jota
Published: July 2007

Conventional high‐density digital recording using a rotary head requires a high‐accuracy servo system with a high precision in mechanics. By combining double‐track scanning and data rearrangement, a nontracking method by which all data can be reproduced in order has been developed. By using this method, it is shown that a tracking accuracy of ± 100 μm for a track pitch of 9.8 μm is obtained compared to a conventional value of ±5 μm. A stamp‐sized cassette and a compact digital audio tape recorder are developed using this nontracking method and evaporated metal tapes.
Magnetic force microscopy for high‐density point magnetic recording
Authors: Ohkubo Toshifumi , Yanagisawa Keiichi , Kaneko Reizo , Kishigami Junichi
Published: July 2007

A scanning probe microscope (SPM) which can depict physical properties by scanning a sharp tip onto the surface of a material of interest has recently been developed. Further intensive work is being carried out for imaging finer patterns in an attempt to apply its technique to high magnetic recording density.

This paper considers a magnetic case and very fine bits are written in a Co‐Cr/Permalloy perpendicular medium by using a very sharp tip of a magnetic material and then detected by the same tip. As one attempt to increase recording density, a bidirectional field recording scheme has been examined where an overwriting was performed. The recording density in connection with a detection signal (magnetic field gradient) is discussed.

Based on a systematic experiment using various radii of the tips, the recording density in the bidirectional case was found to be twice that for a unidirectional field recording. The linear density of 4000 ‐ 5000 fr/mm and the bit‐line width of about 500 nm were confirmed.
Influence of plating bath treatment on characteristics of non‐electrolytically plated metal film resistors
Authors: Aoki Hiroo , Moriyama Minoru
Published: July 2007

A plated metal film for a resistor with medium resistance around 1 kω is too thin to achieve reproducibility in the characteristics. However, it was found that if the oxygen content in the plating solution is reduced by boiling and feeding nitrogen gas through the solution, the plating time is reduced and the reproducibility of the resistance is improved.

It was found also that as the aging period of the plating solution increases, the plating efficiency increases. The damp proof, initial resistance distribution, current noise, thermal coefficient of resistivity (TCR), and resistance change before and after thermal treatment of the resistive films plated in a nitrogen gas‐bubbled solution with low oxygen content are superior to those of resistive films plated in untreated solution. The superior properties of resistors plated in the modified plating solution are due to a more uniform film thickness. However, the short period load characteristics of the resistors plated in the modified and nonmodified solutions exhibit no difference.
Desired mode excitation by power additive signal injection in a multiple‐device cavity combiner
Authors: Tanaka Satoshi , Nogi Shigeji , Fukui Kiyoshi
Published: July 2007

This paper describes the elimination of undesired mode suppression in a multiple‐device cylindrical cavity combiner caused by the effect of excitation of the desired power‐combining mode due to external signal injection. Mode analysis is carried out to derive the condition of undesired mode suppression and of sustaining the desired mode oscillation and to prove the capability of perfect combining of the output powers of the multiple‐device structure and the power of injected signal. Experiments with TM020‐mode cavity confirmed the theory.
Finite element analysis of excitation and transmission problems of magnetostatic forward volume wave
Authors: Hano Mitsuo , Kondo Motomi , Awai Ikuo
Published: July 2007

A finite‐element formulation is described and some numerical results are presented for excitation and transmission problems of magnetostatic forward volume wave. The governing equation for the vector potential is obtained through Maxwell's equations under the magnetostatic approximation.

First, numerical results for radiation impedances of the magnetostatic wave agreed well with analytic solutions. Second, the reflection and transmission characteristics of the magnetostatic wave for a metal strip are analyzed. The reflection coefficient changes periodically with the width of the conductor and its periodicity agrees with a wavelength of the magnetostatic wave. In the case of a narrow strip, the interaction of evanescent waves becomes significant, resulting in a finite reflection coefficient when the width approaches zero.
Nanometer‐fabrication process and ghz‐range low‐loss saw filters
Authors: Yamanouchi Kazuhiko , Lee Chang‐Soo
Published: July 2007

Recently, the frequency range allocated to mobile communication has been extended to the gigahertz band (quasi‐microwave). The filters used in RF stages for this high‐frequency application require wide bandpass characteristics and must have ample attenuation outside this bandpass frequency.

This paper describes the fine lithography technology necessary for fabricating surface acoustic wave devices used at the gigahertz band and also a low insertion loss surface acoustic‐wave (SAW) filter.
Reliability improvement of polyimide‐insulated al‐alloy interconnection against package resin shrinkage stress
Authors: Sakuma Noriyuki , Homma Yoshio
Published: July 2007

New methods to reduce the deformation failure of the polyimide‐insulated multilevel interconnection and nondestructive measuring method to estimate the failure are presented. Deformation failure of the interconnection was found to be detected more sensitively by electrically measuring yields of via‐chain patterns of the two‐level interconnection located around test chip corners than by observing the first‐level Al‐alloy line deformation directly. Reduction of the alloy line failure was examined by analyzing which part of the resin causes the shrinkage stress which in turn causes the alloy line failure. It is shown that both improving the package resin adhesion to the LSI chip and using a resin with a smaller thermal expansion coefficient were remarkably efficient in reducing the alloy line deformation failure.
Admittance characteristics of au/p‐si schottky diode with damage induced by reactive ion etching
Authors: Asai Akira , Ohachi Tadashi , Taniguchi Ichiro
Published: July 2007

Reactive ion etching (RIE) is known to alter electrical characteristics by creating a damaged layer on the surface of the etched substance. An Au/p‐Si Schottky diode was formed on a silicon surface which was etched by RIE using CF4 gas. It was found that excess dc conductance and inductive susceptance were observed in the current voltage (I‐V) and the admittance frequency (Y‐f) characteristics under forward bias conditions, respectively. These results are explained by assuming the existence of deep‐level traps induced by RIE in the depletion region of the diode. Assuming a damage depth distribution of 10 nm, the experimental values of inductive susceptance are able to calculate by following parameters of the deep‐level traps induced by RIE; Er ‐ Ev = 0.33 (eV) and NT = 1 × 1019 (cm−3).
Tantalum electrolytic capacitor employing polypyrrole as solid electrolyte
Authors: Yamamoto Hideo , Fukuda Minoru , Isa Isao , Yoshino Katsumi
Published: July 2007

The conventional tantalum electrolytic capacitor is made by anodically oxidizing sintered porous tantalum metal powder to form tantalum oxide film, followed by precipitating manganese dioxide by thermal decomposition of the tantalum oxide film soaked in manganese nitrate solution. The electrical conductivity of manganese dioxide is as low as 10−2 to 10−1 S/cm, and manganese dioxide is poor in its electrical property, in particular, the high‐frequency characteristic.

In this paper, a precoating layer with a slightly higher resistance is used. The polypyrrole film is deposited by electrolytic polymerization using the precoating layer as the anode. It is found that the capacitor with polypyrrole formed by chemical oxidative polymerization has superior electrical properties compared to the capacitor formed by using manganese dioxide instead of a precoated layer. Using hydrogen peroxide as the oxidizer for chemical oxidative polymerization, polymerization of pyrrole can be achieved even inside the sintered body and the electrical conductivity and thermal stability of the polymer were excellent. The resultant capacitor has excellent electrical and temperature characteristics, its lifetime is long, and it can be surface‐mounted.
Analysis of overwrite mechanism in magnetic recording
Authors: Itoh Kenya , Tagawa Ikuya , Nakamura Yoshihisa
Published: July 2007

Although there is a necessity to achieve excellent overwrite (O/W) in magnetic disk write‐read equipment, the O/W mechanism has not been clarified sufficiently. Accordingly, the investigation of the O/W mechanism by experiment and by a finite element method simulation incorporating a magnetization model has clarified that during O/W, not only the field of the head but also the field generated by the magnetization distribution of the medium (inside field) and rewrite action exert influence on O/W characteristics. From the fact that the inside field changes with the recording density of the signal, modeling was done on the write density dependence of O/W characteristics and verification was made by simulation and experiment.

Moreover, from the viewpoint of O/W, a comparison was made of perpendicular magnetic recording and longitudinal magnetic recording. As a result, for the combination of ring head and longitudinal film medium, although the O/W characteristics are degraded with the increase of the O/W signal recording density, in perpendicular magnetic recording the experimental result that the O/W erased value takes a maximum value when the recording density of the overwrite signal is half that of the prerecorded signal in perpendicular magnetic recording is obtained. Thus, it became possible to clarify the mechanism by using a model taking into consideration the inside field.
Frequency stabilization of a semiconductor laser using the faraday effect of the saturated absorption spectroscopy signal of rb atoms
Authors: Ueno Takashi , Nakazawa Takao , Nakano Hiroyuki , Sato Takashi , Shimba Minoru
Published: July 2007

To stabilize the oscillation frequency of a semiconductor laser by using an absorption spectrum of atoms and molecules as a frequency reference, modulation of an injection current of the laser has commonly been adopted since it gives a high detection sensitivity. However, as a result, the oscillation frequency becomes broadened, which is a drawback.

To overcome this difficulty, a new method has been proposed which utilizes the modulation scheme resulting from the Faraday effect of Rb atoms and thus no direct modulation is needed. In a conventional method using a normal absorption spectrum, detection sensitivity is limited by a spectrum broadening due to the Doppler effect. The stability has been improved one order of magnitude by using a saturated absorption spectroscopy method, compared to the conventional method. Also, with this method, a number of stabilized frequency points is increased. An oscillation frequency can be controlled by changing the dc magnetic field for the Faraday effect modulation for a frequency range over about 8 GHz around the frequency corresponding to Rb‐D2 lines.
Analysis of nonreciprocal phase characteristics of magneto‐optic channel waveguides using finite‐element method
Authors: Zhuang Xiu‐Ping , Koshiba Masanori
Published: July 2007

To evaluate nonreciprocal phase characteristics of a magneto‐optic channel waveguide, the formulation of a finite‐element method based on a scalar wave approximation is discussed here for the first time. This problem is ascribed to the problem of solving a nonlinear eigenvalue equation. However, a simple iterative method is proposed here for solving the nonlinear eigenvalue equation. The validity and usefulness of the present method are demonstrated in analyzing magneto‐optic rib waveguides and magneto‐optic ridge waveguides. A discussion to increase a nonreciprocal phase shift in those waveguides also is given.
Evaluation of heating condition for collapse of fluoride glass tubes
Authors: Sakaguchi Shigeki
Published: July 2007

A heating condition for the collapse of fluoride glass tubes is examined, and a thermal history is discussed. So far, theoretical discussions on the collapse have been made only for the case of a contraction along a tube‐radial direction as a viscous flow of glass. This paper discusses an evaluation method of a contraction along not only the radial but also axial directions by taking into account the effect of heat source traverse. The evaluation is made by numerically solving simultaneous equations, a thermal conduction equation and a viscous flow equation. The method provides the information of a thermal history time temperature relation. Heating conditions are discussed for various traverse speeds and temperature profiles of a heating source. Based on the thermal history thus obtained, the distribution of crystallites grown in a glass is calculated. An excess scattering loss after a collapse is estimated.
A method for analyzing properties of rectangular waveguides of steeply tapered width
Authors: Suga Takashi , Ishihara Fujio
Published: July 2007

A method is described for calculations of the characteristics of the tapered waveguide by means of the electromagnetic field method (normal mode expansion method) in which many higher‐order modes are taken into account. The tapered waveguide to be treated is assumed to be straight along the axis and its thermal loss is assumed negligible. The shape is such that the generated higher‐order mode sequence contains only one parameter. (As an example, either m or n is constant in the TEmn modes.) In the eigenmode analysis of such a tampered waveguide, it is possible to derive solutions which agree with the rigorous solutions taking into account the infinitely many higher‐order modes with sufficient accuracy in practice by means of an application of the extrapolation with relatively few higher‐order modes. The validity of the results is confirmed by experiments. The present method can be applied to a structure in which the slope of the taper is almost 90° (or a step shape) so that it has a wide application range.
Fabrication of a monolithic capacitive pressure sensor for gauge pressure measurement
Authors: Esashi Masayoshi , Uehara Daiji
Published: July 2007

A pressure sensor integrated with a capacitive relative pressure detector and capacitance‐detection circuit was fabricated and its characteristics were evaluated. The humidity resistance of the pressure sensor was discussed, and it was confirmed that the influence of humidity to the device could be minimized.
Microcrystallization process of hydrogenated amorphous silicon films
Authors: Motohashi Mitsuya , Kashu Akiko , Homma Kazuaki , Fukami Toyoji
Published: July 2007

The interface barrier height at the a‐Si:H/a‐SiO:H interface to hydrogen increases with the microcrystallization of a‐Si:H. In this study, using the fact that the barrier height is dependent on the hydrogen effusion characteristic, the microcrystallization time of a‐Si:H was measured.
Zno thin films prepared by rf magnetron sputtering method on sio2/si substrate
Authors: Takada Syuichi , Fujinaka Masaharu
Published: July 2007

A zinc oxide (ZnO) thin film was formed by RF magnetron sputtering and the dependencies of the crystallinity, optical propagation characteristic and electrical resistivity of the film on the substrate temperature during film deposition were investigated.

The ZnO film crystallinity was excellent and the standard deviation of the angle in the X‐ray rocking curve which represents the sharpness of the c‐axis orientation was less than 1°. The crystallinity was improved and the film resistivity decreased from 107 to 102 Ω ± cm as the substrate temperature increased.

The optical propagation loss was around 1.78 dB/cm for the TE0 mode. It was concluded that not only the film orientation but also the film density must be taken into account to achieve a ZnO film with good optical propagation characteristic.
Circuit theoretical study on the lifetime of the resonant state
Authors: Ohtani Naoki , Sanada Hirofumi , Nagai Nobuo , Suzuki Masakiyo , Miki Nobuhiro
Published: July 2007

With a view to investigating the operating speed of a quantum effect device, considerable work has been carried out on the lifetime of the resonant state. The lifetime of the resonant state in a multiple barrier structure is defined as the time constant with which the existence probability of the electron is attenuated. This is a quantum theoretical transient phenomenon.

In this paper, by means of a complex‐valued equivalent circuit proposed previously by the authors, this transient problem is discussed from a circuit theoretical viewpoint. First, the complex frequency variable (Laplace variable) is related to the complex energy which permits a circuit theoretical investigation on the lifetime. It was found that the real part of the complex frequency, which makes zero the sum of the admittances looking to the left and the right, corresponds to the lifetime. By means of a numerical experiment, a double‐barrier structure is studied and compared with the research results reported previously. The error of the lifetime estimated from the half‐value width also is studied. In addition, a symmetric triple barrier structure is studied. It is found that a lifetime exists that cannot be estimated from the half‐value width.
Generalized rat‐race circuit with an arbitrary power‐split ratio
Authors: Ohta Isao , Kawai Tadashi
Published: July 2007

A rat‐race circuit consists of four constituent transmission lines whose length at the center frequency is an odd multiple of one‐quarter wavelength. One of these four lines is designed to have a difference in length by an odd multiple of one‐half wavelength in comparison to the remaining three. Especially, the circuit made of three one‐quarter wavelength transmission lines and one three‐quarter wavelength line with a total length of 3/2 wavelengths has been used most widely as the basic circuit.

In this paper, with a view to finding the general constitutive conditions for a rat‐race circuit with an arbitrary power‐split ratio, a uniaxially symmetric circuit made of transmission lines with an arbitrary length and an arbitrary characteristic impedance is treated and the relationship is found between the electrical lengths and the admittance values of each transmission line section determined by the matching condition and the power‐split ratio. It is found that a circuit design is fundamentally possible if the ring length is more than one‐half wavelength.

It is shown that a power divider with an arbitrary power‐split ratio can be designed with a circuit longer than one wavelength and that there is flexibility in the choice of the admittance values and the lengths of each section for a given power‐split ratio if the ring length is constant. Further, from the practical viewpoint, the foregoing results are used for miniaturization of the circuit and for design of large differences of power division with appropriate admittance values. The theoretical results are validated by experiments.
Extended ray theory for analyzing electromagnetic scattering process on two‐dimensional smooth objects
Authors: Ikuno Hiroyoshi , Ohmori Toshiyuki , Nishimoto Masahiko
Published: July 2007

When the field scattered by a cylindrical object is analyzed using a pulse of short duration, the scattered field can be observed as a pulse train with appropriate propagation times for responses containing information on the polarization direction of the incident wave, object shapes, and materials. By analyzing and discriminating these pulses, the scattering phenomena can be resolved. In the present study, an extended ray theory (ERT) is proposed as a method to systematically analyze the scattering process of the electromagnetic wave by a smooth two‐dimensional object.

Here, it is demonstrated that the scattering process of the electromagnetic wave can be represented by six elementary processes. For the analysis of these elementary processes, two charts are constructed on the geometrical optics ray and the diffraction ray by means of the ray‐tracing technique. It is shown that the use of these charts can evaluate the scattered field including the contribution from the complex ray in the caustic shadow region in addition to the real ray. In fact, to verify this theory, the propagation times of the scattered rays from the real scattering center and the complex scattering center extracted from the charts were computed. When the transient responses are analyzed based on the results, it was possible to explain all response waveforms in terms of the contribution from the real and complex geometric rays and the diffraction rays.
Asymmetry analysis of two‐dimensional optical phase‐modulation characteristics of a microchannel spatial light modulator (MSLM)
Authors: Hori Terushige , Toyoda Haruyoshi , Hara Tsutomu
Published: July 2007

The two‐dimensional optical phase modulation characteristics are described for an optical address‐type microchannel spatial light modulator (MSLM). Especially, the asymmetry of the optical phase modulation characteristics is analyzed. Here, the diffraction efficiency is measured when a fringe pattern is written into the device in addition to the optical phase modulation of the MSLM. The results obtained are an optical phase modulation of 2π radian and a diffraction efficiency of about 17 percent. This is believed to be caused by the change of index of refraction due to the lateral electric field at the boundary between the bright and dark patterns. Also shown is the result of the correlation experiment using this characteristic effectively.
Design of miniaturized dielectric duplexer with attenuation poles
Authors: Matsumoto Haruo , Nishikawa Toshio
Published: July 2007

A design method is conceived for a miniaturized antenna duplexer with attenuation poles. Its effect is indicated by using it as an antenna duplexer for the 800‐MHz portable telephone. The transmitting filter has a band‐rejection filter characteristic of an elliptic function type while the receiving filter has a Chebyshev bandpass filter with attenuation poles. Previously, the design of these filters has been carried out by an optimum design using an iterative approximation from an initial design value. Hence, a large amount of computation time was required.

This paper proposes a design method without an iterative approximation. In the transmission filter, resonators with a low characteristic impedance are used. In the conventional band‐rejection filter design of an elliptic function type, the linearity of the reactance slope of the resonators is degraded and the insertion loss near the passband edge increases. A method of compensating for this increase is presented. In the receiving filter, the design equation for the conventional Chebyshev characteristic was modified. It is shown that a bandpass filter characteristic with attenuation poles can easily be designed. A branching circuit is added to these filters, and an antenna duplexer is constructed with a minimum number of components by the circuit transformation. The computed values of the filter characteristic agreed well with the actual example. In comparison with the optimization method based on the iterative approximation, the amount of computation for the design was about one‐twentieth.
Computer numerical analysis of the high‐speed performance of a two‐phase schottky barrier CCD with a metal shielding layer
Authors: Yonei Kenji , Omoto Osamu
Published: July 2007

A two‐phase Schottky barrier CCD structure with a metal shielding layer that is designed to be a highspeed transfer device is described, and its performance is numerically analyzed in order to estimate its characteristics. The proposed CCD is a device structure electrically shielded by the metal layer so that the clock pulse applied voltage at the transfer electrode does not influence the external circuit, thus making it suitable for three‐dimensional ICs. The transfer electrodes are formed by arranging 1‐bit, four‐metal electrodes alternately in narrow gaps and wide gaps. The transfer electrodes are driven by a sawtooth pulse voltage, and the charge is transferred between two wide gap regions. In order to theoretically analyze the charge transfer phenomenon and to clarify the high‐speed characteristics, a two‐dimensional computer simulation using the Schottky‐Read‐Hall model and the dependence of electric field on drift velocity is developed. The charge transfer is produced by a potential well moving in the charge transfer direction in the initial period of the charge transfer process and is done by the drift current in a high electric field in the final period. The clock frequency is 3 GHz in the Si‐CCD and 8 GHz in the GaAs‐CCD for an applied voltage of 3.5 V and a charge transfer efficiency of 99.99 percent at a bit length of 4 m̈m.