bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Solar Cells Fabricated by a New Ion Implantation Concept
Authors: Itoh Haruo , Tokiguchi Katsumi , Warabisako Terunori , Saitoh Tadashi , Tokuyama Takashi
Published: March 2014

The effects of implanted H+, H2
+ and PH+ ions on the P+ ion implanted solar cell characteristics are first investigated. It is clarified that H+ ions have a detrimental effect on cell performance, whereas the effects of H2
+ and PH+ ions are less than for H+ ion. According to the results, a new ion-implanter is designed. It has a simple mass separator which only removes H+ ions from the main ion beam extracted from the PH3 gas discharge source. This enables improvement of the phosporus dose rate.
Solar cells are fabricated using this implanter, and conversion efficiencies over 10% are obtained without an anti-reflection coating. The feasibility of high throughput and low cost in cell fabrication is demonstrated.
Instability Observed in InP (MIS) Schottky Barrier Solar Cells
Authors: Kamimura Kiichi , Kunioka Akio
Published: March 2014

Instabilities have been observed in the electric and photovoltaic characteristics of InP (MIS) Schottky barrier solar cells. The degradation has been more serious for n-type sample than for p-type sample. The degradation in n-type sample seems to be caused by the decrease of the barrier height and in p-type sample, it seems to be explained in terms of the increase in sheet resistance of the gate metal.
High Efficiency MOS Solar Cells by Anodic Oxidation Processes
Authors: Yamamoto Hidekazu , Moniwa Masahiro , Sawada Takayuki , Hasegawa Hideki
Published: March 2014

Preparation of GaAs, InP and Si single-crystal MOS solar cells by anodization in various modes is investigated. Both passive and active modes of anodization are found to increase the open-circuit voltage with respect to that of the bare Schottky cell. Best result is obtained by active anodization of n-GaAs. Passive anodization with a high formation voltage results in an anomalous reduction in photocurrent. A detailed analysis of cell currentvoltage characteristics indicates that cell behavior is dominated by interface-states.
Reflection Characteristics of Open Metal Strip Arrays for SAW Resonators
Authors: Kojima Toshihiro , Tominaga Junichi , Suzuki Tatsuo
Published: March 2014

This paper presents theoretical and experimental results for the reflection characteristics of open metal strip arrays. In the analysis, the equivalent circuit model for an interdigital transducer is applied, and the expression of the reflection coefficient is derived in a closed form by the image parameter theory. In the investigations on the substrate of LiNbO3 (128° rot. Y, X-prop.), a good agreement between the calculated and experimental results is obtained.
A Piezoelectric Composite Resonator Consisting of a ZnO Film on an Anisotropically Etched Silicon Substrate
Authors: Nakamura Kiyoshi , Sasaki Hiromasa , Shimizu Hiroshi
Published: March 2014

A thickness-mode piezoelectric composite resonator consisting of a ZnO film on a silicon substrate was studied. The relation between the effective electromechanical coupling factor and the ratio of the substrate thickness to the piezoelectric-film thickness was theoretically analyzed. In order to obtain a lower-order overtone composite resonator with high electromechanical coupling, a thin diaphragm structure fabricated by anisotropic etching of a silicon wafer was utilized as a substrate. An effective electromechanical coupling factor of 8.9% was experimentally obtained for the 2nd overtone mode.
Dependence of Transducer Performance of Lamb Wave Multiplexer on Terminal Condition
Authors: Toda Kohji , Shinoda Yoshiaki
Published: March 2014

The performance of a Lamb wave transducer is strongly affected by the electrical termination. The transducer consists of three electrodes; one is on the bottom surface, the others are interdigital electrodes on the top surface. Interdigital electrodes have the phase difference of one quarter of the wavelength of the Lamb wave and are terminated by resistances. Using the characteristic of the dependence of the acoustical signal passing through the transducer region on terminating resistances, two types of Lamb wave multiplexers are demonstrated.
Statistical Analysis of the Effects of Finger Dispersion on the Electrical Characteristics of SAW Filters
Authors: Ono Masaaki , Wakatsuki Noboru , Tominaga Hideki
Published: March 2014

Dispersion of the electrical characteristics of SAW filters mainly depends on the variations of the finger width and the finger defects of interdigital transducers. Statistical analyses are performed to estimate the effect of variations of the finger parameters on the electrical characteristics, using a Smith's equivalent circuit and Monte Carlo computer technique. This theoretical approach was practically applied to a SAW filter for the NTSC/USA TV system and was compared with experimental results to confirm its validity.
ZnO Piezoelectric Films Formed by RF Reactive Ion Plating
Authors: Machida Mitsuzo , Shibutani Masanobu , Murai Tsuneo , Murayama Yoichi
Published: March 2014

Highly oriented ZnO films were synthesized successfully on glass, fused quartz, silicon and sapphire substrates with high reproducibility by RF reactive ion plating. Metal zinc was evaporated from an alumina crucible in an RF discharge of oxygen gas at a pressure of 10-4 Torr (10-2 Pa). The piezoelectrical properties of the ZnO films for the surface acoustic wave (SAW) device were evaluated by electrical measurements. The high coupling factor (k) of the ZnO films was measured at between 0.08 and 0.09. The SAW TV-PIF filters fabricated by the ion plated ZnO films were found to be excellent.
Temperature-Stable SiO2/LiTaO3 Structure for SAW Devices
Authors: Inaba Ritsuo , Wasa Kiyotaka
Published: March 2014

A temperature dependence of delay time and phase velocity of SAW on a layered structure of SiO2/X-115°Y LiTaO3 was studied. A zero temperature coefficient of delay time was obtained for a normalized SiO2 film thickness of k·h≃1.0 at room temperature. The temperature variation of delay time observed was less than 10 ppm in a temperature range from 0°C to 60°C. The bandpass filter characteristics with a center frequency of 170 MHz were also demonstrated.
Focusing Effects of Surface Acoustic Waves in Crystalline Solids
Authors: Tamura Shin-ichiro , Honjo Katsuhiko
Published: March 2014

Focusing of surface acoustic waves (SAW) due to elastic anisotropy of substrate crystals is investigated theoretically. For propagation on the (001) plane of GaAs, we find strong focusing effects of the SAW along certain directions. We also find that the number of independent pure-mode axes lying in the focusing directions is just one on the (001) surface.
Measurement of Flow Rate by Ultrasonics
Authors: Yamamoto Miaki
Published: March 2014

This paper deals with ultrasonic flowmeters based on the sing-around method and Doppler effect. The principles of the flow measurement are shown and essential points concerned with the design of the transducers and their arrangement on the pipe walls are discussed. Some applications for pipe and open channel flow measurement are described and explained briefly.
An Electrostatic Voltage Sensor Using Surface Acoustic Waves
Authors: Kasahara Yukio , Inaba Ritsuo , Wasa Kiyotaka
Published: March 2014

A compact electrostatic voltage sensor has been developed using a delay line type SAW oscillator. An additional collecting electrode is settled on a surface of a piezoelectric substrate between input and output interdigital transducers. The electrostatic voltage applied to the collecting electrode is detected by a frequency change of the SAW oscillator. Piezoelectric ceramics with d=-42×10-12
C/N are used for making the SAW oscillator. The sensitivity achieved is 0.64 Hz/V at oscillation frequency of 23 MHz.
Study on Measurement of Pile Driven into the Ground by Impulsive Driving Method
Authors: Motooka Seiichi , Watanabe Tsutomu , Okujima Motoyoshi
Published: March 2014

A technically new pulse-echo method was devised to measure the full length of a steel pipe pile driven into the ground through the impulsive driving method. Then, various experiments were performed to examine the possibility of measurement by this method. Measurements of frequency characteristics of sound attenuation constant in a steel pipe buried in a pit filled with sand were made. Consequently, it is expected that the impulsive driving method is useful for measurement of the full length of pipe pile driven into the ground.
Nonlinear Effects in Surface Acoustic Waves
Authors: Nakagawa Yasuhiko
Published: March 2014

Theoretical and experimental investigations are made of nonlinear effects in surface acoustic waves, such as harmonic generation, parametric mixing, convolution, bulk-wave generation, and dc effects. The normal-mode method is used to solve nonlinear problems, and good agreement is obtained between theory and experiment.
Optical Transmission Modulation Mechanisms Caused by Acoustic Domains in CdS
Authors: Hata Tomonobu , Niwa Masaaki , Hada Toshio
Published: March 2014

An acoustic domain in CdS crystals modulates a radiated optical beam near the intrinsic absorption edge. This paper reports that the equivalent band-gap alteration caused by the scattering effect and intrinsic absorption are superimposed and cause optical modulation. The equivalent band-gap alteration is dependent on sample thickness but the intrinsic absorption is caused by the Franz-Keldysh effect and is not affected by sample thickness.
Acoustical Farfield of Short Impulsive Sounds Radiated from Baffled Pistons
Authors: Otani Takahiko , Takeda Masayuki
Published: March 2014

The sound field of short impulsive sounds shows quite different aspects from those of steady sinusoidal sounds. Impulsive waveforms are considerably deformed in radiation as well as in reception, even in linear propagation. Direct analytical calculations (in function of time) of directional deformation in farfield of short impulsive sounds are resolved in cases of rectangular and circular piston in infinite baffle. Farfield sound pressure for arbitrary shaped pistons is expressed by the retarded acceleration from the piston and the piston shape function in terms of time.
Measurement of Ultrasonic Attenuation in Solid under Hydrostatic Pressure
Authors: Kosugi Toshio , Hiki Yosio
Published: March 2014

A problem in measuring sound attenuation in a solid in hydraulic fluid has been treated on a theoretical and an experimental basis. When an ultrasonic pulse reflection method is used for the measurement, an apparent attenuation due to the sound transmission from the ends of the solid specimen into the fluid is fairly large and strongly dependent on applied pressure. The attenuation was represented as a function of pressure, and calculated results were compared with experiments. Attenuation measurements were made at 30–90 MHz sound frequencies on a LiF crystal under pressure up to 3000 kg/cm2. Agreement between the calculated and experimental pressure dependences was satisfactory.
Frequency Variable Oscillator Using a Monolithic SAW Phase Shifter
Authors: Urabe Shuuji , Yuki Shuomi , Habuka Tatsuzi
Published: March 2014

A new frequency variable oscillator with a monolithic SAW phase shifter is reported. A 214 MHz monolithic SAW phase shifter is fabricated on a silicon substrate with ZnO film. A voltage controlled phase shift is measured and discussed. An SAW oscillator is implemented with this phase shifter and its frequency is controlled by external voltage. A frequency shift of 120 kHz (a relative variation of 560 ppm) and excellent modulation characteristics are obtained without an external phase shifter.
The Piezoelectric Properties of Fluorinated Copolymers
Authors: Yamada Takeshi
Published: March 2014

The piezoelectric properties were studied for vinylidene fluoride (VDF)-trifluoroethylene (TrEE) copolymers. The melt-crystallized films, without any stretching, showed strong piezoelectricity in the wide range of VDF molar composition. Especially for the copolymer with 55 mole % of VDF, large piezoelectric constant was obtained under a poling condition at a low electric field. The ferroelectric to paraelectric phase transition was observed at the temperature range between 60°C and 125°C for the copolymers with a VDF molar content between 37 and 80% by the measurements of dielectric and piezoelectric constants.
Electromechanical Characteristics of Tungsten-Bronze Type Solid Solution Crystals in BaO–SrO–Na2O–Nb2O5 System
Authors: Mikami Noboru , Ikeda Takuro
Published: March 2014

Characteristics of the tungsten-bronze type solid solution crystals in the BaO–SrO–Na2O–Nb2O5 system have been investigated. The crystals were pulled from the melts, and their elastic, piezoelectric and electrooptic constants were measured. Some noticeable performance was found.
Interrelation of Electrostriction with Phase Transition Diffuseness –Improvement of the Temperature Characteristics of Electrostriction–
Authors: Uchino Kenji , Kuwata Jun , Nomura Shoichiro , Cross Leslie E. , Newnham Robert E.
Published: March 2014

Recently-developed electrostrictive materials have been classified on the basis of the origin of their diffuse phase transitions for the purpose of seeking how to improve the temperature characteristics of transducers. A simple interrelation between the temperature coefficient of electrostriction and the phase transition diffuseness is demonstrated in the solid solution systems Pb(Mg1/3Nb2/3)O3–Pb(Mg1/2W1/2)O3 and Pb(Mg1/3Nb2/3)O3–PbTiO3, in conjunction with the short-range order in B-site cations. A cluster model, extended from the random compositional fluctuation model by Smolensky and Rolov, is proposed for a diffuse phase transition in complex perovskites with short-range ordering of the cation. Based on this model, the improvement of the thermostability has been made in the Pb(Mg1/3Nb2/3)O3–PbTiO3 ceramics by adding Pb(Mg1/2W1/2)O3 or Ba(Zn1/3Nb2/3)O3, resulting in a temperature coefficient less than 1% deg-1.
Investigation of Amorphous State of PbTiO3 and Its Crystallization Process
Authors: Takashige Masaaki , Nakamura Terutaro
Published: March 2014

Investigations have been made of rapidly quenched amorphous PbTiO3 utilizing, Raman spectroscopy, dielectric measurement and electron microscopy. The as-quenched samples crystallize on heating in the temperature region between 500 and 600°C. By annealing samples above the crystallization temperature, gradual changes in physical properties toward the perfect crystalline state have been observed.
Phase Transition of PbTiO3 in the Low Temperature Region
Authors: Uesu Yoshiaki , Sakemi Yuji , Kobayashi Jinzo
Published: March 2014

The lattice constants of PbTiO3 were accurately measured in the low temperature range by using an x-ray dilatometer for clarifying the existence of phase transitions. The lattice constants a and b begin to differ from -90°C with the decrease of temperature. The difference is extremely small but unequivocal within the accuracy of our experimental method. It is also found that the lattice constant c begins to deflect there from the linear temperature dependence in the higher temperature region.
A Piezoelectric Ceramic Material and a Bimorph for Auto-tracking in VTR
Authors: Kitamura Tomosaburo , Kodera Yoichi , Miyahara Kosuke , Tamura Hidemasa
Published: March 2014

In order to improve auto-tracking device, a piezoelectric ceramic material and a carbon fiber-reinforced-plastic shim plate of bimorph were investigated. Introduction of Bi and Zn atoms into a ternary Pb(Ni1/3Nb2/3)O3–PbTiO3–PbZrO3 system gives rise to a pronounced increase in piezoelectric activity and densification when material is subjected to the usual sintering procedure. It was found that the deflection of the bimorph is 1.5 times as large as the deflection of conventional bimorph with isotropic metal shim plate when the direction of fiber orientation falls along the length of the bimorph element.
A CCD Imager Using ZnSe-Zn1-xCdxTe Heterojunction Photoconductor
Authors: Terui Yasuaki , Yoshino Masaru , Ogura Mototsugu , Nakayama Mitsuo , Yoneda Masato , Chikamura Takao , Miyata Yutaka , Horiuchi Shiro
Published: March 2014

A new CCD imager, having ZnSe-ZnCdTe heterojunction photoconductor as a photosensor which is vacuum-deposited on the CCD scanner, has been fabricated. The device has 404 (H) × 506 (V) scanning elements, each element measures 24 µm(H) by 14 µm(V), and the imaging area is 9.0 mm(H) × 6.7 mm(V) in size which is applicable to 2/3 inch camera format. The CCD scanner is fabricated with denuded zone which defines the defect-free device. A glass-reflow process is introduced to obtain the high breakdown of the heterojunction diode.
The experimental result are as follows,; The sensitivity is 0. 16 µA/lx (3200 K). The horizontal and the vertical resolution are 280 and 450 TV lines, respectively. Dark current is 2 nA/cm2 for the photosensor (27°C). The signal to noise ratio is above 60 dB. The smearing suppression is effective for reducing the blooming phenomenon under the intense light illumination. The successful blooming suppression is achieved by this PLOSS structure device with metal screen grid. The high light exposure is allowable up to 1000 times as intense as the saturation exposure.
Experimental Study of Amorphous Silicon Integrated Circuit
Authors: Nara Yasuo , Matsumura Masakiyo
Published: March 2014

Integration of amorphous silicon field-effect-transistor is investigated. It is shown experimentally that the new inverter circuit which consists of an n-channel enhancement mode driver FET and a p-channel load FET has excellent step-like transfer characteristics. A small-signal gain of more than 10 was obtained. A nine-stage integrated ring-oscillator operated for the first time. The power delay product and the minimum propagation delay time were about 480 pJ and 110 µs, respectively, which agreed well with the analytical results. It is pointed out that power-delay product could be reduced by more than three orders of magnitude.
Solid-State Color Image Sensor Using Hydrogenated Amorphous Silicon
Authors: Baji Toru , Shimomoto Yasuharu , Matsumaru Haruo , Koike Norio , Akiyama Toshiyuki , Sasano Akira , Tsukada Toshihisa
Published: March 2014

The device structure, fabrication and performance of a solid-state color image sensor using hydrogenated amorphous silicon as a photoconductive materal are reported in this paper. The number of photodiodes made of nitrogen doped amorphous silicon is 485 (V) × 384 (H), and they are scanned by n-MOS switches. An RGB color filter array is put on the chip to make a 2/3'' size single chip color sensor. This device features high spectral sensitivity, high blooming suppression, low lag and little burning.
A High-Speed I2L Process/Structure for VLSI
Authors: Hirao Tadashi , Ishikura Hidenobu , Ohsaki Saburo , Tubouchi Natsuro
Published: March 2014

A high-speed I2L gate for VLSI application has been successfully designed, characterized and demonstrated. The high-speed performance has been achieved in an oxide isolated I2L with a buried-base structure by means of a thin epitaxial layer and heavily doped extrinsic base, and characterized by 0.87 ns of minimum delay time at fan-out of 1 and 1.6 ns at fan-out of 3. The I2L characteristics have been superiorly controlled by optimizing the impurity profile with the reduced pressure epitaxy: For example, the deviation of breakdown voltage (BVCEO) is almost 10% and the deviation of delay time is less than 4%. The influence of device structure on the gate speed has been investigated and then the typical performance for the high-speed gate array which allows propagation delay time down to 3.7 ns at 275 µA/gate injection current has been obtained with the use of 3.4 µm design rule, a dual injector structure and the optimized process.
A Josephson Latch-Decoder
Authors: Hanyu Isamu , Suzuki Hideo , Hasuo Shinya , Yamaoka Toyoshi
Published: March 2014

This paper proposes a Josephson decoder named a latch-decoder. It is constructed from two-input AND gates operated in the latching mode. Main features of this decoder are high speed operation and simple circuit construction. Discussions are focused on the principle and design of the latch-decoder. An experimental 3-to-8-bit decoder is also demonstrated.
Characterization of Loss Mechanism in 1.3 µm InGaAsP/InP Laser Diodes by Acoustical and Optical Measurements
Authors: Yamanishi Masamichi , Suemune Ikuo , Nonomura Kazuhiro , Mikoshiba Nobuo
Published: March 2014

1.3 µm InGaAsP/InP lasers were investigated by the measurement of currentinjection-induced acoustic (CIA) signals. The experimental results are explained by our theory, based on saturable absorption model due to inter-valence-band transitions. An unsaturated loss coefficient over 30 cm-1 in 1.3 µm InGaAsP/InP lasers is predicted with k.p perturabation theory, explicitly taking into account of the effect of anisotropy of effective masses of heavy hole and split-off valence bands. A characteristic temperature T
0 of 86 K at room temperature is estimated by the present theory.
Impact-Ionization of Excitons and Application to Gate-Controlled Bistable Switching
Authors: Yamaguchi Eiichi , Kobayashi Takeshi
Published: March 2014

Excition impact-ionization effects on low temperature photocurrent were investigated in Ge pin-MIS triodes. A simple model, taking into account the exciton impact-ionization process, was given to account for the observed anomalous temperature dependence and field dependence of the photocurrent on the device. The feasibility of the exciton impact-ionization due to the gate field was checked on the MIS-structure. On this device, gate-controlled bistable switching behaviour was expected to be obtained and was experimentally demonstrated.
Preparation of Nd3+ Doped Gd3Ga5O12 Films by Liquid-Phase Epitaxy
Authors: Okuda Takashi , Ando Koji , Koshizuka Naoki
Published: March 2014

Epitaxial films of Nd3+ doped Gd3Ga5O12 garnet were grown on pure Gd3Ga5O12 substrates up to 130 µm in thickness at a growth rate as fast as 2 µm/min. The films were examined by means of X-ray diffraction, X-ray fluorescence analysis, optical absorption, fluorescence, and Raman scattering. Fluorescence decay time of 170 µs was obtained for the films doped with 1.4 mol% of Nd3+. Possibility of an application of the films to a thin-fil m laser is discussed from the points of waveguiding property and optical quality of the films, and it is concluded that epitaxially grown films of Nd3+ doped Gd3Ga5O12 possess requisite material qualities for waveguiding laser application.
B, Sb and Si Liquid Metal Alloy Ion Sources for Submicron Fabrication
Authors: Gamo Kenji , Inomoto Yasumasa , Ochiai Yukinori , Namba Susumu
Published: March 2014

B, Sb and Si liquid metal alloy ion sources have been fabricated and basic characteristics such as current-voltage relations, angular current intensity, energy distribution and mass spectra have been measured. Characteristics of ion beam focusing systems are also discussed. It was observed that the energy distribution width (FWHM) of various ion species obtained for Sb alloy sources decrease with increasing the charge to mass ratio of the ion beam. It was also observed that the mass spectra varied slightly with a total ion source current. These ion sources could be operated for more than 10 h without any change in mass spectra.
(Invited) VLSI Fine Technology and Its Problems
Authors: Arai Eisuke
Published: March 2014

This paper reviews problems encountered in the 1 µm process development for 256K MOS RAM and forecasts submicron technology in the future. The 1 µm process consists of electron beam direct writing, dry etching, Mo-poly double gate and faulttolerant technologies. The major problems encountered are various process-induced defects caused by using electron beam direct writing, dry etching and thinner films.
To realize an efficient submicron process, it is necessary to further reduce all the defects as well as to develop a device structure with high applicable voltage. The limiting device dimensions for MOS devices depend upon circuit form. The minimum dimensions are obtained for the CMOS form.
High Voltage Low On-Resistance VDMOS FET
Authors: Nakagawa Akio , Yoshida Jiro , Utagawa Tadashi , Tsukakoshi Tsuneo , Tanabe Hirohito , Kuramoto Tsuyoshi
Published: March 2014

Recent theoretical analyses on MOS FETs revealed that most of the on-resistance came from the epi-layer so that thin and low resistivity epi-layer was desirable for low on-resistance. This paper presents a new junction termination technology suitable for achieving near ideal breakdown voltage for such low resistance epi-layer. This paper also describes design optimization of source pattern and impurity diffusion profile with aid of a two dimensional numerical model. On the basis of these techniques, a power MOS FET with 450 V sustaining voltage and 0.35 Ω on-resistance was realized at a high manufacturing yield.
Arc-Discharge Produced Amorphous-Silicon Solar-cells
Authors: Uchida Yasutaka , Kobayashi Osamu , Matsumura Masakiyo
Published: March 2014

Quality and uniformity of the arc-discharge produced amorphoussilicon (a-Si) films have been investigated by using pin type solar cells. Six substrates, each of which being 5 cm×30 cm, were inserted into a reaction tube of 7.5 cm in diameter and a-Si films were deposited simultaneously on every substrate. A film thickness of 1 µm±0.2 µm and solar Cell efficiency of 1.24%±0.5% were obtained in more than a half of the substrate area. The cell fabricated in a smaller reaction tube showed an efficiency of 5.3%. These results indicate that the arc-discharge decomposition method is applicable for depositing a-Si films of high quality and large area.
Difference of Characteristics of a-Si: H Solar Cells between under Illumination and Dark
Authors: Warashina Masatoshi , Ushirokawa Akio
Published: March 2014

The purpose of this paper is to show that the a-Si: H p-i-n type solar cells become more conductive as the incident light intensity increases. A new method for the determination of the series resistance R
s, the shunt resistance R
sh and the diode factor (n-value) is given from the measured dc current I-the dc voltage V curve under the illumination of a fixed light intensity. Consequently, as the light intensity increases from zero to 140 mW/cm2, it is found that R
s decreases from 47.3 ohm to 0.1 ohm and that R
sh decreases from 2.2×105 ohm to 7×102 ohm in the case of #E7-1 sample as well as the other samples. The increase of the n-value with increasing light intensity suggests that the a-Si: H cells show a tendency toward the property due to the recombination current in the space charge region near the p-i junction.
Analysis of the Photovoltaic Characteristics of p-i-n a-Si Solar Cells
Authors: Tsuda Shinya , Nakamura Noboru , Nakashima Yukio , Tarui Hisaki , Nishiwaki Hidenori , Ohnishi Michitoshi , Kuwano Yukinori
Published: March 2014

Theoretical considerations were made on an amorphous solar cell, called the “multi-bandgap structure”, with a realistic model. It is shown that the theoretical limit efficiency of the three-bandgap amorphous solar cell is estimated to be 24% by using materials which have optical bandgaps of 2.0 eV, 1.7 eV, and 1.45 eV. The materials of this structure were also considered, and the possibility of multi-bandgap amorphous solar cells was shown.
Characterization of a-SiC: H as a Window Material for p-i-n a-Si Solar Cells
Authors: Tawada Yoshihisa , Tsuge Kazunori , Nishimura Kunio , Kondo Masataka , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: March 2014

A series of experimental investigations on the characterization of methane based and ethylene based a-SiC: H as a window mateial has been made. Chemical bonding structure of two kinds of a-SiC: H films has also been explored from infra-red absorption structural analysis. An experimental verification for the wide gap window material in the amorphous silicon solar cell is shown on methane based and ethylene based a-SiC: H.
The methane based a-SiC: H/a-Si : H heterojunction solar cell shows a larger short-circuit current density than the ethylene based one. IR absorption analysis shows that methane based a-SiC: H film is a rather ideal amorphous SiC alloy as compared with the ethylene based one. It has been found through these investigations that the chemical bonding structure is an important factor for a window material.
Zn3P2/ITO Heterojunction Solar Cells
Authors: Suda Toshikazu , Kobayashi Mitsuyoshi , Kuroyanagi Akio , Kurita Shoichi
Published: March 2014

Heterojunction solar cells of Zn3P2/ITO have been fabricated by rf sputter depositing ITO films onto Zn3P2 multiple crystal, and their electrical and photovoltaic properties are studied. Multiple crystal boules of Zn3P2, 12–16 mm in diameter and 3 cm long with grain size of 1–5 mm in diameter, and resistivity ρ of 40–105 Ω-cm have been formed by vapor phase transport. The ρ of as-grown Zn3P2 has been reduced significantly by Ag doping above 400°C. A V
oc of 0.24–0.32 V and a J
sc of 13–26 mA/cm2 are measured and the power conversion efficiency of 1.1% is obtained without AR coating at simulated AM 1. The J-V characteristics suggest tunneling as the dominant conduction mechanism. A spectral response of J
sc shows a good band-pass behavior between 360 nm and 830 nm.
High-Efficiency Selenium Photovoltaic Solar Cells
Authors: Kunioka Akio , Nakada Tokio
Published: March 2014

Selenium thin layer solar cells have been fabricated in an ITO–Se structure. The cells exhibit an acceptable conversion efficiency of about 2.5 percent under AMI illumination, with an open-circuit voltage of 0.5 V, a short-circuit current density of 10 mA/cm2, and a fill factor of 0.5. The photovoltaic performance makes a very good comparison with that of ordinary selenium cells.
Wavelength Division GaAlAs/GaAs Solar Cells Grown by MOCVD
Authors: Nobuhara Hiroyuki , Sakai Shiro , Umeno Masayoshi
Published: March 2014

GaAs and GaAlAs are grown on GaAs substrates by MOCVD method. The crystal growth conditions and doping characteristics are clarified. The wavelength division solar cell which is one of the most promising candidate to overcome the conversion efficiency of the conventional heteroface solar cell is fabricated. The results show poor photovoltaic properties of Ga1-x
Al
x
As(x≃0.3) p-n junction compared with that of GaAs. This degradation in sensitivity is attributed to the oxygen contamination in GaAlAs.
Application of Ultrasonic Fractography to Visco-Elastic Materials
Authors: Takahashi Kiyoshi , Matsushige Kazumi , Sakurada Yasuhiro
Published: March 2014

In order to explore the possibility of ultrasonic fracture modulation in visco-elastic materials, a comparison is made of fracture velocity values for PMMA and Epoxy which were obtained simultaneously by high speed photography and ultrasonic fractography. A satisfactory agreement between the two sets of values confirms the applicability of the method to visco-elastic materials. In connection with the fractographical results, some advantages of this method are discussed.
Acoustic Interferometry (Measurement of Internal Stress Distribution in Solid)
Authors: Imamura Tatsuo , Ueha Sadayuki , Tsujiuchi Jumpei
Published: March 2014

An acoustic interferometric method is proposed to measure the internal stress distribution in a solid. The stress distribution can be determined from the shift of acoustic interference fringes, which was experimentally shown using aluminum test blocks.
New Types of Ultrasound Focusing Transducer Sysmtems
Authors: Yamada Ken , Shimizu Hiroshi
Published: March 2014

New types of focusing transducer systems are proposed and their performance is verified by experiments. One focusing system is composed of a conventional focusing transducer and an isotropic solid medium with high longitudinal wave velocity. This system can generate a narrow sound beam and contribute to the improvement of a lateral resolution over a wide axial range. Another system is a zone lens that has circular grooves of varying diameter on its radiating surface. This lens can easily be fabricated and gives focused fields almost equal to those by conventional acoustic lenses.
Holographic Sonar 3D Underwater Ultrasonic Imaging Using Thinned-out Image Reconstruction
Authors: Sato Tomomasa
Published: March 2014

This paper describes a thinned out image reconstruction method which reduces the amount of calculations with a little sacrifice of image SN ratio. By establishing such role separations as the transmitting array being used to obtain only lateral resolutions and the receiving array only the field of view, the redundant elements are thinned out if the transmitting aperture length and the distance between one receiving element and the next are equivalently kept. Three dimensional imaging experiments show that this method can effectively be used for the purpose of obtaining images for rough survey or measuring distance.
SAW Convolver Utilizing Sezawa Wave in a Monolithic ZnO/Si Configuration
Authors: Minagawa Shoichi , Okamoto Takeshi , Asai Ryuichi , Tsubouchi Kazuo , Mikoshiba Nobuo
Published: March 2014

The optimum design for the monolithic Sezawa wave ZnO/Si convolvers is clarified on crystal cuts and SAW propagation directions in silicon. Theoretical analysis was carried out using an equivalent transmission line circuit model of SAW. The calculated bilinear convolution characteristics well agree with the experimental results. The terminal convolution efficiency FT=-47.5 dBm was obtained in the [001] direction on (110) Si. Dynamic range over 80 dB was observed in the [011] direction on (100) Si. The temperature and dc gate bias stability characteristics are described.
Preparation of Highly C-Axis Oriented ZnO Thin Films by Plasma-Enhanced Metalorganic Chemical Vapor Deposition
Authors: Shimizu Masaru , Yamamoto Takashi , Shiosaki Tadashi , Kawabata Akira
Published: March 2014

Thin-film ZnO with a high degree of c-axis orientation has been grown on glass substrate by plasma-enhanced metalorganic chemical vapor deposition at a substrate temperature of 200°C and rf input powers higher than 220W. In this system the ZnO films were fabricated by reacting diethylzinc with CO2 gas. The crystallographic properties and surface morphology of the films were greatly affected by the rf input power level, the substrate temperature and the growth rate.
Brillouin Scattering in BiVO4 at High Temperatures
Authors: Tokumoto Hiroshi , Unoki Hiromi , Ishiguro Takehiko
Published: March 2014

The Brillouin scattering in BiVO4 was measured at high temperatures up to 600°C stressing the dependence of the Brillouin frequencies on the propagation direction of phonons. From the angular dependence of the Brillouin frequencies, we have found that the directions where the velocities of phonons have extreme values differ from the crystalline axes by either 10° or -35° in the tetragonal (001) plane because of the non-vanishing elastic constant c
16. In the temperature dependence curve of Brillouin frequency for a [110]-phonon with [11̄0]-polarization, softening behaviour was observed at around 255°C.
Critical Slowing Down in Lipid Bilayer Membrane Studied by a Differential Ultrasonic Resonator
Authors: Mitaku Shigeki , Jippo Toshiyo , Kataoka Ryoichi , Date Takeshi
Published: March 2014

A differential ultrasonic resonator was developed for the measurements of ultrasonic velocity as well as absorption in dilute aqueous suspensions of biological materials. The accuracy of the resonator was improved by analyzing the resonance peak shape with the aid of a microcomputer; the accuracy of 1×10-5 for velocity and 5×10-5 for absorption per wavelength was obtained in the frequency range between 0.8 and 8 MHz. An aqueous suspension of multilamellar lipid bilayers was measured by this apparatus, and a marked slowing down of the relaxation time was observed in the vicinity of a gel-to-liquid crystal phase transition.
Ultrasonic Attenuation in Ice Crystals
Authors: Tamura Junichi , Hiki Yosio
Published: March 2014

Ultrasonic attenuation in single crystals of ice grown by the Bridgman method has been measured as functions of frequency (15∼85 MHz) and temperature (-8.0°C∼–0.1°C). A resonance damping of ultrasound was always observed in the crystals. Experimental data were analyzed on the basis of the vibrating string model of dislocation, and the following results have been obtained: Dislocation density in the crystals is of the order of 106 cm -2; pinning of dislocations in the crystals may be due to impurity ions, probably Cl- ions; density of dislocations fluctuates violently and increases rapidly near the melting point.
An Acoustic Imaging System by Use of a Lamb Wave Device
Authors: Hayama Masaru , Toda Kohji
Published: March 2014

An imaging technique suitable for constructing acoustic images of flaws inside materials is presented. A Lamb wave device, with arched interdigital electrodes divided into four parts, operates at a liquid-solid boundary. The device is useful to examine the acoustic discontinuity in two orthogonal directions. The frequency of the electrical signal applied to the arched electrodes and the thickness of the liquid layer between the Lamb wave device and the test sample are essential for the adjustment in obtaining acoustic images. The technique in a reflection mode and some results are described.
Composite SAW IF Filter Separating the Sound and Picture Signals
Authors: Yamada Jun , Toyama Tatsuro
Published: March 2014

A new surface acoustic wave filter for a sound multiplexing broadcasting system has been developed. It has two channels of a sound and a picture filter, which is fabricated in 128° Y cut LiNbO3. The self and adjacent sound traps in the picture filter are much deeped than the previous one by improved diffraction compensation techniques for anisotropic substrate. The twin peaks in the sound filter has broad enough, and suppresses the band between the sound and picture carriers sufficiently.
Effect of Porous Structure to Piezoelectric Properties of PZT Ceramics
Authors: Hikita Kazuyasu , Yamada Kouji , Nishioka Michihiro , Ono Mikiya
Published: March 2014

Porous Pb(Zr0.53 Ti0.47)O3 ceramics with three dimensionally interconnected structure were prepared by modifications of conventional powder sintering methods. The piezoelectric and elastic properties of the porous PZT were investigated by related with pore structures such as porosity and pore size. As porosity increased, permittivity decreased linearly and
piezoelectric coefficient d
33 increased gradually, so the voltage output coefficient g
33 increased. The g
33 value was 200–300×10-3 (Vm/N) at the porosity of 0.65.
Piezoelectric and Dielectric Properties of Composites of Synthetic Rubber and PbTiO3 or PZT
Authors: Banno Hisao , Saito Shigeo
Published: March 2014

The piezoelectric and dielectric properties, particularly those important for hydrophone application, of flexible composites of synthetic rubber and piezoelectric ceramic particles are reported in this paper. Also a theoretically derived “modified” cubes model is presented, which generalizes the parallel, series and cubes models.
Dielectric Characteristics of Modified SrTiO3 Ceramics and Their Application to a High-Voltage Capacitor
Authors: Nishigaki Susumu , Nakamura Junichi , Murano Kanji , Tatsuki Koichi
Published: March 2014

Dielectric characteristics of the ceramics in the (100-x) (Sr0.50Pb0.25Ca0.25)TiO3·x(Bi2O3·3TiO2) system were investigated for x=0∼8.25. The maximum dielectric constant at Curie temperature increased markedly under a DC biasing field. 100% increase, for example, was observed at -22°C under a 3 kV/mm DC biasing field for x=1.56. The increase of the dielectric constant under a high DC biasing field was also found in ceramic capacitors for high-voltage use which were fabricated with the use of the present material with x=4.3.
Self Focusing of Surface Acoustic Waves
Authors: Nakagawa Yasuhiko
Published: March 2014

Theoretical and experimental results are reported for self focuning of surface acoustic waves in LiNbO3. The scalar wave equation that includes the third order nonlinear term could be solved numerically. The correspondence between theory and experiments was obtained.
SAW Propagation Characteristics on Li2B4O7
Authors: Ebata Yasuo , Suzuki Hitoshi , Matsumura Sadao , Fukuda Katsuyoshi
Published: March 2014

Lithium tetraborate (Li2B4O7) was reported as a new piezoelectric material which has zero temperature coefficient of delay (TCD) and moderately high coupling coefficient (k2). This paper estimates SAW propagation properties (k2 and TCD) on Li2B4O7 over the full cuts and propagation directions. Further, the TCD dependency on aluminum layer is also assessed, considering construction of a SAW device with aluminum electrodes. As a result, it is found that there is a region of zero TCD and high coupling coefficient (≧1%).
Numerical Calculations on Ultrasonic Fields and Echoes in Fluid
Authors: Yamada Hisao
Published: March 2014

By the method of Rubinowicz and Schoch, the CW field of a curved circular radiator was calculated numerically. The results were visualized by contour maps of amplitude and phase. Echoes from a rigid circular reflector were calculated assuming an idealized simple distribution of sound pressure around the surface of the reflector.
Two-Dimensional Precise Measurement of the Fracture Velocity in Acrylic Polymers Using Ultrasonic Fractography
Authors: Takahashi Kiyoshi , Matsushige Kazumi , Sakurada Yasuhiro
Published: March 2014

Using ultrasonic fractography two-dimensional fracture velocity measurements of acrylic polymers, PMMA and P(MMA/MA), with different specimen configuration are performed under various temperatures. The fracture just after the onset of instability starts almost discontinuously. The initial velocity is shown to fall in a small range, 90 to 150 m/s, almost independent of the experimental conditions with an exceptional case loaded slowly at a low temperature.
Light Scattering Study of UHF Ultrasonic Properties in Fused Quartz
Authors: Choi Pak-Kon , Takagi Kenshiro
Published: March 2014

High-resolution Bragg reflection technique, which had originally been developed for ultrasonic measurement in liquids, was recently modified for the investigation of solids. Output of an Ar+ laser is scattered by sound waves and the scattering angle is determined with an optical beating system, which gives sound velocity. The longitudinal and the shear wave velocities were measured in a fused quartz at 20°C over the range 200–1200 MHz and 90–310 MHz, respectively. The obtained results, v
L=5973 m/s and v
s=3755 m/s are in good agreement with the previous values at low frequency. The absorptions were obtained using the optical detection of the resonance spectrum of the standing wave within the sample.
Measurement of Elastic Anisotropy of Solid Using an Interdigital Transducer for Underwater Ultrasonic Wave Excitation
Authors: Nomura Tooru , Nakamoto Takamichi , Shiokawa Showko , Moriizumi Toyosaka , Yasuda Tsutomu
Published: March 2014

One interdigital transducer couple (IDTs) on a piezoelectric substrate has been used to investigate the acoustic properties of anisotropic materials. An IDT can radiate underwater ultrasonic wave in oblique directions with respect to the substrate surface. When the acoustic beam is incident on the solid sample-water interface near the Rayleigh angle, the reflection field is equal to the superposed fields of the specular reflection and the reradiation from the leaky SAW excited on the sample. The velocity and the attenuation of the leaky SAW on the sample can be obtained from the measured trailing field due to the reradiation.
A Liquid Velocity Meter Using a Liquid Delay Line Oscillator
Authors: Toda Kohji , Urabe Heijiro
Published: March 2014

A system for liquid velocity measurement is proposed using a liquid delay line oscillator with interdigital transducers. The transducer operating at a liquid-solid boundary is used as a sound beam radiator or a detector. The oscillation frequency of the delay line oscillator is a function of the velocity of a flowing liquid. The operation principle for the velocity meter is presented with confirming experimental results.
Arrangements of Transmitter- and Receiver-Arrays to Collect Acoustic Holographic Data without Redundancy
Authors: Nagai Keinosuke , Kimura Minoru
Published: March 2014

This paper presents two arrangements of transmitter- and receiver-arrays to collect acoustic holographic data rapidly without redundancy. For uncomplicated utilization, such arrangements should be adapted to conventional numerical imaging procedures: the Fourier transform method and the backward propagation method. These procedures are modified first for suitability to multiple transmitters and receivers. Then, two arrangements of arrays are obtained corresponding to the two procedures. Experimental results are also displayed to demonstrate the discussion.
Effect of Lanthanum as a Promoter on Fe-Co/SiO2 Catalyst for Fischer-Tropsch Synthesis
Authors: Abbasi Ali , Ghasemi Mohamadreza , Sadighi Sepehr
Published: March 2014

Iron-Cobalt catalyst is well known from both operational and economical aspects for Fischer-Tropsch synthesis. Effort to increase the efficiency of this kind of catalyst is an important research topic. In this work, the effect of lanthanum on characteristic behavior, conversion and selectivity of a Fe-Co/SiO2 Fischer-Tropsch catalyst was studied. The Fe-Co-La/SiO2 Catalysts were prepared using an incipient wetness impregnation method. These catalysts were then characterized by XRF-EDAX, BET and TPR techniques, and their performance were evaluated in a lab-scale reactor at 250ºC, H2/CO = 1.8 of molar ratio, 16 barg pressure and GHSV=600 h-1. TPR analysis showed that the addition of La lowered the reduction temperature of Fe-Co catalyst, and due to a lower temperature, the sintering of the catalyst can be mitigated. Furthermore, from the micro reactor tests (about 4 days), it was found that lanthanum promoted catalyst had higher selectivity toward hydrocarbons, and lower selectivity toward CO2. © 2014 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)
Activity of Aniline Methylation over Fe-Cu-Cr Ternary Spinel Systems
Authors: George Reni , George Kochurani , Sugunan Sankaran
Published: March 2014

A series of spinels having thegeneral formula CuCr2-xFexO4 with x=0.25,0.75, 1.25, 1.75 were prepared by co-precipitation method. The catalysts werecharacterized by various physico-chemical methods like XRD, BET, UV-DRS, SEM,EDX, TPD etc. The reaction of aniline with methanol was studied in a fixed-bedreactor system as a potential source for the production of various methylanilines. It was observed that systems possessing low ‘x’ values are highlyselective and active for N-monoalkylation of aniline leading toN-methylaniline. Reaction parameters were properly varied to optimize thereaction conditions for obtaining N-methylaniline selectively and in betteryield. Among the systems CuCr1.75Fe0.25O4 isremarkable due to its very high activity and excellent stability. Under theoptimized conditions N-methylaniline selectivity exceeded 91%. CuCr1.25Fe0.75O4gives better conversion than CuCr1.75Fe0.25O4in CuCr2-xFexO4 series. The Lewis acid sitesof the catalysts are mainly responsible for the good catalytic performance.  © 2014 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)
Neural Networks for Optimal Feedback Control
Authors: JAGANNATHAN S. , XU HAO
Published: March 2014

This article describes the use of principles of neural networks and learning mechanism therein to design optimal feedback controllers. Both discrete‐time and continuous‐time dynamical systems, with and without a communication network, that combine features of standard adaptive and optimal control techniques are presented. In addition, advanced neural network controllers and their algorithms are also briefly discussed.