bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrothermal Growth and Characterization of ZnO Single Crystals
Authors: Sakagami Noboru , Shibayama Kimio
Published: March 2014

Large flawless crystals of ZnO up to 25×10×5 mm3 in size have been grown hydrothermally in a specially designed autoclave. Difficulties on the hydrothermal growth of ZnO single crystals were almost surmouted by in situ determination of solution temperatures under operating conditions. The characteristics of the growth crystals are discussed on the basis of the correlation with growth conditions, and it is found that a nonstoichiometry in the grown ZnO is enhanced with being apt to involve O vacancies due to a reductive atomosphere under hydrothermal conditions and also is related to their some properties.
The Pyroelectric Sensor
Authors: Kuwano Yukinori , Yokoo Toshiaki , Shibata Kenichi
Published: March 2014

This report is an outline of pyroelectric sensors. The properties of various materials for pyroelectric sensors were investigated. Various types of construction and performance factors which give pyroelectric sensors their particular features are described. Several applications of the pyroelectric sensor are also listed. In conclusion, the future trend of the pyroelectric sensor is described.
New Electromechanical Materials and Their Applications
Authors: Uchino Kenji , Nomura Shoichiro
Published: March 2014

Three current topics in creative developments of electromechanical materials are reviewed: first, polymeric piezoelectric materials such as polyvinylidene fluoride with low elastic stiffness; second, ceramic-plastic composites with 3–1 phase connectivity; third, electrostrictive materials with large elastic strains free from hysteresis and aging effects.
Preparation of PbTiO3 Ferroelectric Thin Film by Laser Annealing
Authors: Matsui Yasushi , Okuyama Masanori , Hamakawa Yoshihiro
Published: March 2014

PbTiO3 thin films having a considerably good ferroelectric property have been prepared on Pt foil and Si wafer by rf sputtering at low temperatures of 350∼450°C and a subsequent laser annealing treatment using a cw CO2 laser. A clear phase transition from the paraelectric phase to the ferroelectric phase in the irradiated region has been found without temperature rise of the periferal region. Laser annealing effects of electronic properties of SiO2–Si interface have been also investigated in MOS structures with the PbTiO3 film by DLTS method and it is found that Pt electrode on SiO2, is effective to avoid a deterioration of electronic state near the interface.
Ferroelectric Liquid Crystal and Its Application
Authors: Yoshino Katsumi , Inuishi Yoshio
Published: March 2014

Ferroelectricity in chiral smectic liquid crystals and their mixture with various materials are discussed in detail. The various applications of these properties of ferroelectric liquid crystal are also discussed.
CW Measurement of Sound Velocity Difference in Two Liquids
Authors: Toda Kohji , Katayama Kazumi
Published: March 2014

A technique for measuring the sound velocity difference in two liquids which makes use of interdigital transducers is developed. There exists a linear relationship between the sound velocity difference in two liquids and the phase difference of two delayed output signals, which is converted to a dc voltage by using a phase comparation technique. A prototype with an 10.0 MHz input signal and three times reflections at the liquid cavity surface is fabricated and tested successfully.
Trap Depth of KTaO3 Doped with Transition Metal Ions
Authors: Akishige Yukikuni , Yamamoto Yujiroh , Ohi Kikuo
Published: March 2014

The enhancement and bleaching of electron spin resonance of photochromic centers (Ni3+–V0–2e and Fe3+) in KTaO3 have been measured as a function of time in the temperature range from 100 K to 340 K. The electron trap levels associated with the photochromic centers were estimated from the thermally stimulated current measurement. A band model is proposed to explain the kinetics of the electron transfer.
Dielectric Properties of Lossy KH2PO4 Crystals
Authors: Nakamura Eiji , Itoh Kazuyuki , Ushio Satoshi , Abe Kohji , Yoshida Hirohisa
Published: March 2014

Single crystals of KH2PO4 have been prepared from aqueous solutions which contain a large amount of KOH. These crystals have high dielectric constants and dielectric losses at room temperature and show dielectric dispersion below about 105 Hz. The dispersion frequency increases with the increase of the amount of KOH in the aqueous solution. In the ferroelectric phase, these crystals exhibit low dielectric constants and show anomalous frequency dependence of the coercive field.
Electrical and Optical Properties of Hot-Pressed A(A1/3'Nb2/3)O3-PbZrO3-PbTiO3 (A=Ba, Sr, A'=Pb, Ca, Sr) Ceramics
Authors: Yokosuka Masaru , Miura Shinsuke , Ochiai Tsutomu , Marutake Masakazu
Published: March 2014

Investigations have been made on the hot-pressed ceramics of the solid solution xA(A1/3'Nb2/3)O3–(1-x)[(Pb(Zr
y
Ti1-y
)O3], where A=Ba or Sr, A'=Pb, Ca or Sr. Curie temperatures, lattice constants, dielectric constants and electromechanical coupling coefficients have been determined as a function of x for various systems near the tetragonal-rhombohedral morphotropic phase boundary. Polished specimens in the compositional range 0.10<x<0.20 and 0.40<y<0.60 have been found to have high optical transmittance and to show pronounced electrooptic effects. The phase diagram of the system Ba(Sr1/3Nb2/3)O3–PbZrO3–PbTiO3 has been also studied and the existence of the intermediate phase, which is likely to be antiferroelectric, has been confirmed.
Electrical and Optical Properties of Hot-Pressed A(Zn1/3Nb2/3)O3–PbTiO3–PbZrO3 (A= Ba, Sr, Ca) Ceramics
Authors: Ochiai Tsutomu , Yokosuka Masaru , Miura Shinsuke , Marutake Masakazu
Published: March 2014

Electrical and optical properties of hot-pressed ceramics in ternary systems A(Zn1/3Nb2/3)O3–PbTiO3–PbZrO3, where A=Ba, Sr or Ca, have been studied and it has been found that optical transmittances of these ceramics (0.24 mm thick) are more than 60% at 600 nm, and that electromechanical coupling coefficients k
31 are as high as 42% with mechanical quality factors Q
M as low as 27, near the morphotropic boundary between the tetragonal and the rhombohedral phases.
The phase diagram of the ternary system Sr(Zn1/3Nb2/3)O3–Pb(Ti–Zr)O3 has been determined from X-ray analysis combined with dielectric measurements.
(Invited) Microdefects in Czochralski-Grown Silicon Crystals and Their Application to Gettering Technique
Authors: Kishino Seigô
Published: March 2014

Microdefects in Czochralski-grown (CZ) silicon crystals are induced by thermal treatments used in an LSI process. They are detrimental to device performance, if they are formed near the surface. The microdefects originate in the precipitation of oxygen involved in CZ crystals. However, it is possible to reduce the microdefect density after thermal treatments without decreasing the oxygen concentration by controlling crystal growth condition. On the other hand, the microdefects serve as gettering sites for both harmful impurities and surface defects, if their formations are confined to the interior of the wafer. This is called the intrinsic gettering (I-G) phenomenon. The I-G technique is successfully applied to a lifetime improvement, a heavy metal gettering, and an elimination of surface defects.
(Invited) Solution Growth of II–VI Compounds
Authors: Aoki Masaharu , Washiyama Masako , Nakamura Hiroshi , Sakamoto Kunihiro
Published: March 2014

Crystal growth of Zn and Cd chalcogenides from a variety of solutions has been studied. Solutions investigated included Te, Se, Te–Se mixture and As2Se3. Te corner in the Zn–Se–Te ternary phase diagram has been determined. High quality ZnSe crystals have been grown from Se solution, and also from As2Se3. Phosphorus doped ZnSe was grown from (As2Se3 + P) solution. A shallow acceptor related to phosphorus hasbeenestimated to be (84±4 meV). Thinlayers of ZnSe were grown on ZnS and ZnTe substrates by liquid-phase epitaxial technique utilizing Te or Te–Se as solvents.
(Invited) Mechanism of Dry Development and Dry Etch Resistance of Resist
Authors: Tsuda Minoru , Oikawa Setsuko
Published: March 2014

Theoretical investigations were carried out on the mechanism of dry development and dry etch resistance of resists comprised of PMIPK and aromatic azides. The hydrogen bridged system produced in resist coatings by radiations followed by annealing operates as an electronic excitation energy quenching system. The quenching mechanism was elucidated in details.
A Novel Technology for Self-Aligned Contact Formation
Authors: Sakamoto Mitsuru , Saito Manzo , Hamano Kuniyuki
Published: March 2014

A new processing technology that is effective to prepare self-aligned contact (SAC) holes in silicon gate MOSFET's is demonstrated. In this technology, thermally grown silicon nitride film is utilized as a mask for polysilicon gate oxidation and the oxidation of the polysilicon gate is carried out in two separate process steps. As a result, thick silicon oxide with high breakdown voltage and small coupling capacitance has been reproducibly formed on the polysilicon gate. With this technology, MOSFET's with self-aligned contact holes have been successfully fabricated. This SAC formation method is found to be applicable to MOS VLSI's.
Ammonia-Annealed SiO2 Films for Thin-Gate Insulator
Authors: Kato Ichiro , Ito Takashi , Inoue Shin-ichi , Nakamura Tetsuo , Ishikawa Hajime
Published: March 2014

Thermal nitridation of a thin SiO2 film in purified NH3 gas at elevated temperatures produces a strong protective layer against impurity diffusion. This enables fabrication of a reliable MOS structure with a high work function gate material such as p+ polysilicon. This combination is advantageous for miniaturized MOSFETs because a reasonable threshold voltage is obtainable without a high dose of channel ion implantation which deteriorates carrier mobilities and interfacial properties. Experimental results indicate easy incorporation of a nitrified SiO2 film in the conventional MOS process.
Improvement of Characteristics in SOS/MOSFETs by Laser Annealing
Authors: Kobayashi Yutaka , Ikeda Takahide , Nakamura Minoru , Suzuki Takaya
Published: March 2014

The crystalline quality of silicon layers grown on sapphire substrate with a vapor phase epitaxial growth is improved by exposing the layers to multiple laser irradiation of a suitable energy density. MOSFETs are fabricated on the improved SOS wafers. The channel mobilities of these MOSFETs increased to about 130% and the leakage currents decreased to about 1/6 of those of unimproved SOS wafers. Laser Raman spectroscopy and an etching method are used to reveal the cause of these improvements, which is found to be a decrease in crystal defect density brought about by the laser annealing.
Trapped Ar Induced Deformation of Magnetron Sputtered Al Film Overlaid with Plasma SiN Film
Authors: Harada Hiroshi , Yakushiji Hisao , Nishioka Tadashi , Kotani Hideo , Hirata Yoshihiro
Published: March 2014

Effects of heat treatments on magnetron sputtered Al (SP-Al) films overlaid with plasma silicon nitride (P-SiN) films were investigated. Trapped Ar in SP-Al films during sputtering deforms SP-A1 and/or P-SiN films to cause voids ranging from a few to a hundred micrometers in diameter because of the low permeability for the P-SiN film. In cases of CVD-SiO2 and PSG as overlayer materials, less voids are formed because of their higher permeabilities and their higher deposition temperatures. The voids decrease with decreasing line width of patterned SP-Al films since narrower lines trap less amounts of Ar. In order to reduce the voids, substrate heating at 300°C during sputtering and heat treatment at 450°C in vacuum after sputtering were carried out, resulting in reduction of the voids to about one fifth.
Novel Low Temperature (\lesssim300°C) Annealing of Amorphous Si by Scanned High Energy (∼2.5 MeV) Heavy Ion Beam
Authors: Nakata Jyoji , Kajiyama Kenji
Published: March 2014

Novel ion beam annealing (HIBA, High energy heavy Ion Beam Annealing) with high energy (∼2.5 MeV) heavy ion beam is presented. By HIBA, an amorphous Si layer is recrystallized below (∼300°C of substrate temperature (much lower than oridinary solid phase epitaxial growth temperature ∼600°C). Also, the temperature just under the beam spot is estimated to be ∼20°C higher at most than that of surrounding region, because of large beam spot size (∼10 mmφ) and rapid scan speed (∼104 cm/s). This low temperature feature is quite different from the conventional furnace, laser, electron or low energy ion beam annealing. After HIBA, impurity As atoms are located at substitutional site with no tetrahedral interstitial component and
are scarcely redistributed.
Pyroelectric Infrared Sensor Using PbTO3 Thin Film
Authors: Okuyama Masanori , Seto Hiroyuki , Kojima Motohiro , Matsui Yasushi , Hamakawa Yoshihiro
Published: March 2014

A pyroelectric infrared sensor made of PbTiO3 ferroelectric thin film constructed on Si wafer has been developed. Pyroelectric output signal is amplified in current mode by a bipolar transistor which is devised on the same Si wafer. The device performance is much improved in high frequency region as compared with that of previous FET mode monolithic sensors, and it can be operated up to a few tens kHz region. Current responsivity of the PbTiO3 film has been also increased by reducing a heat capacity of the sensitive area and the output voltage of the device is 1.1 mV under the illumination of 120 mW/cm2 at 1 kHz which is one order of magnitude larger than that of the previous FET mode structure attached directly to Si wafer. The detectivity is ∼105 cm √Hz/W with bandwidth of 1 Hz at chopping frequency of 1 kHz. The rise time of the response measured under CO2 laser pulse irradiation is about 2.5 µs.
Optical and Electrical Properties of Nitrogen Doped a-Si: H Films for Solid-State Image Pickup Devices
Authors: Shimomoto Yasuharu , Tanaka Yasuo , Yamamoto Hideaki , Takasaki Yukio , Sasano Akira , Tsukada Toshihisa
Published: March 2014

Hydrogenated amorphous silicon (a-Si: H) films deposited by RF sputtering and doped with nitrogen have been found to have high dark resistivity (1013 Ω·cm) and high photoconductivity at a low field. The Fermi level is shifted by 0.2 eV toward the conduction band, compared with undoped film. The spectral response of this film covers the visible region well and a peak quantum efficiency of 1.0 has been obtained at a wavelength of 500 nm. The γ-value of the film is nearly equal to unity for visible radiation. Rise and fall time constants are shorter than 500 µs for a pulsed radiation of 550 nm emitted from an LED. We have found that nitrogen doped n-type a-Si: H films are quite suitable as a photoconductive material for a solid state color imager.
Analysis of Conversion Efficiency of Large Area a-Si: H Solar Cells
Authors: Haruki Hiromu , Uchida Yoshiyuki , Sakai Hiroshi , Nishiura Masaharu , Kamiyama Michinari
Published: March 2014

The conversion efficiencies of 7.0, 5.5 and 4.7% have been obtained for ITO/n-i-p/SS a-Si: H solar cells with 1.2, 49.and 100 cm2 area under AM1 (100 mW/cm2) illumination, respectively. The short circuit current improvement by changing the cell structure from the ITO/p-i-n/SS to the ITO/n-i-p/SS is explained by the lower absorption coefficient of n-type windowside layer in the latter structure. The decrease of the fill factor with increasing cell area is mainly caused by the series resistance due to the ITO film and the grid electrodes and the contact resistance between the ITO film and the grid electrodes.
Optimization of GD a-Si: H Film Property for Photovoltaic Device by Means of the Cross Field Plasma Deposition Technique
Authors: Hotta Sadayoshi , Nishimoto Naoaki , Tawada Yoshihisa , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: March 2014

A systematic study has been made on the relationship between plasma deposition condition and electronic properties of a-Si: H film by employing the cross field plasma deposition technique. Three important processes of deposition mechanism, i.e. i) plasma decomposition, ii) transport of ionized and neutral radicals and iii) compiling of decomposed species were separately identified by this technique. Remarkable improvements in the film quality have been obtained, that is, AM 1 photoconductivity of more than 5×10-4 mho/cm with the optical gap of 1.73 eV in the undoped film deposited at the optimum bias voltage of -50 V and the substrate temperature of 350°C. Another noticeable result is an enhancement of boron doping efficiency realized by applying an appropriate positive bias voltage of + 100 V. These improved films have been utilized to construct p-i-n heteroface solar cells.
NbN, Nb Double-Layered Base-Electrode Josephson Junctions
Authors: Kosaka Shin , Kojima Kazuyoshi , Shinoki Fujitoshi , Shoji Akira , Hayakawa Hisao
Published: March 2014

A new structure of the base-electrode for Josephson devices have been developed in which niobium (Nb) and niobium nitride (NbN) films were sequentially sputtered to form a double-layered structure. Owing to this structure, it is possible not only to reduce the kinetic inductance of the base-electrode due to the small penetration depth of Nb film, but also to obtain good tunneling characteristics with a small subgap conductance due to the surface stability of NbN film. Single-flux-quantum (SFQ) memory cells with this structure have been fabricated and it has been observed that the kinetic inductance is much decreased comparing with that of the SFQ cell with a base-electrode of NbN single layer.
Quasiparticle-Injected Superconducting Weak Link Device
Authors: Sakai Shigeki , Tateno Hiroshi
Published: March 2014

This paper concerns a new three terminal superconducting weak link device, having a third electrode attached to the weak link part for injecting quasiparticles. The structure, the fabrication procedure and the result of the measurement of its static I-V characteristics are presented. As a result, a current gain larger than that of any other Josephson switching devices is obtained. It is found that the larger current gain depends strongly upon the input resistance between the third electrode and the weak link part. The switching speed of the device is also theoretically discussed.
15 mW Single Mode CW Operation of Crank Structure TJS Laser Diodes at High Temperature
Authors: Kumabe Hisao , Tanaka Toshio , Nita Shigeyuki , Seiwa Yoshito , Sogo Toshio , Takamiya Saburo
Published: March 2014

A new high power AlGaAs laser with a window structure, crank type TJS laser, has been developed. The laser operates in a fundamental transverse mode even at 20 mW CW power. The threshold current is reduced to as low as 20 mA by shortening the crank length of the laser and the diode oscillates even above 80°C. The maximum power of the diode is nearly ten times higher than that of a conventional TJS laser. Maximum powers of 200 and 40 mW are obtained in pulsed and CW operation, respectively.
Static characteristics of the diodes and interim status of long term operation are described.
Stable Two-Dimensional Oscillation in a Transverse- Distributed-Feedback Cavity Laser
Authors: Suemune Ikuo , Kohno Motohiro , Yamanishi Masamichi , Uomi Kazuhisa
Published: March 2014

Stable two-dimensional oscillation was otained in a transverse-distributed-feedback cavity laser by establishing the technique to assure the perpendicularity of the grating to the plane mirrors. The threshold current of the two-dimensional mode was lower than that of the one-dimensional mode (conventional Fabry-Perot mode). The measured far-field pattern showed sharp peaks at the theoretically predicted emission angle, and the full width at half maximum of the envelope of the peaks was very narrow (2–3°). The far-field pattern was also highly stable for the change of the injection current.
Anodic Al2O3/InP Interface for Application to Enhancement MISFETs
Authors: Sawada Takayuki , Ishii Kazuaki , Hasegawa Hideki
Published: March 2014

A simple process to grow anodically high quality Al2O3 films on InP using AGW electrolyte is described. Quasi-static and dynamic measurements of the anodic Al2O3/InP MIS interface gave consistent results and indicated that the distribution of interface states was U-shaped in the upper half of the forbidden gap with minimum density of the order of 1011 cm-2 eV-1. Surface Fermi level can be brought up as close as 0.05 eV to the conduction band edge. MISFETs, fabricated directly on semiinsulating InP substrates, operate in enhancement-mode with good saturation characteristics and with an effective mobility of about 850 cm2/V·s.
Film Growth of BeO Using R-ICB Technique and Applications to Electronic Thin Film Devices
Authors: Matsubara Kakuei , Yamada Isao , Takaoka Hiroshi , Takagi Toshinori
Published: March 2014

BeO films prapared by using the reactive ionized-cluster beam (R-ICB) technique are evaluated from the standpoint of crystallinity, and the results of measurements on the optical properties and the thermal conductivities of the films are described. An attempt to grow a BeO film on a Si substrate is made to propose a film formation method for large scale integrated circuits in which both isolation and heatsink are important. In addition, the possibility of surface acoustic wave (SAW) transducers in a GHz-band is proposed on the basis of the experimental properties and of high sound velocity of BeO films grown by the R-ICB technique.
Sputtered n-ITO/p-InP Solar Cells
Authors: Suda Toshikazu , Suzuki Masahisa , Kurita Shoichi
Published: March 2014

Heterojunction solar cells of indium-tin oxide (ITO)/InP have been fabricated by rf sput-tering ITO onto three kinds of p-InP substrates with carrier concentration N
A of ∼1017 cm-3, ∼1016 cm-3, and ∼1015 cm-3 respectively. The forward J-V characteristics for the cells with N
A=∼1017 cm-3 is in good agreement with the tunneling model, whereas the others behave more like emission-recombination current. A fill factor of 0.67, V
oc of 0.73 V, and J
sc of 26.9 mA/cm2 are obtained; the solar power conversion efficiency is then 13.2% under simulated AM 1 illumination without AR coating. From the spectral response of J
sc no evidence for the formation of a buried homojunction is found. This result together with the fact of high efficiency of the cells irrespective of the large lattice mismatch suggests semiconductor-insulator-semiconductor structure.
A Comparison of Spray-Deposited ITO/n-Si and SnO2/n-Si Solar Cells
Authors: Nagatomo Takao , Inagaki Yoshio , Amano Yuji , Omoto Osamu
Published: March 2014

The diode and photovoltaic properties of spray-deposited ITO/n-Si solar cells are very similar to those of SnO2/n-Si devices. These cells have relatively high conversion efficiencies of 11∼13%. The cell performances are affected by the work functions (or electron affinities) of ITO and SnO2 films, and by the interface states. The work functions (or electron affinities) and band gaps of ITO and SnO2 films vary by the preparation techniques. Spray-deposited ITO/n-Si and SnO2/n-Si solar cells do not operate at minority-carrier diodes.
(Invited) Cost Estimates for Flat Plate and Concentrator Collector Arrays
Authors: Shimada Katsunori
Published: March 2014

At the outset of the U.S. National Photovoltaic Program, it was envisioned that a large-scale deployment of grid-connected systems would be essential for photovoltaics to have a significant impact on the solution of the energy problem. To achieve this large-scale deployment, the installed system cost must break even with the net monetary return in terms of deferred energy cost and/or the cost of energy sold back to the grid. However, the current module and installation costs are significantly higher than what are economically viable. Therefore, during the past several years the reduction of the installed module cost has been the major emphasis of the Program.
The cost estimates for three candidate photovoltaic systems (1) flat plate, (2) linear-focus Fresnel concentrator, and (3) point-focus Fresnel concentrator showed that the installed cost of all three systems would be economically viable provided that various technology advancements are achieved and production volume increases as expected.
Light Position Sensitive Silicon Detectors Produced by Using the Epitaxial Growth Technique
Authors: Kim Chisu , Kim Yongcha , Husimi Kazuo , Ohkawa Shoichi , Kikuchi Ko
Published: March 2014

Light position sensitive silicon detector (PSD) of surface barrier type has been made from a N-type epitaxial silicon wafer, in which the epitaxial layer is used as the charge dividing resistive layer. The surface of the epitaxial layer is very clean and at the same time defects in the epitaxial layer is very small compared with the silicon layer produced by using the ion implantation technique. Moreover, uniformity of resistivity of the epitaxial layer is very good. These characteristics are favorable to use the epitaxial layer as the charge dividing resistor of the PSD.
Temperature Dependence of Si Solar Cell Performance under Concentrated Sunlight
Authors: Fujisaki Masahito , Mizukami Noboru , Kitamura Akio , Kuniyasu Hiroshi
Published: March 2014

Temperature dependence of Si Solar Cell performance under concentrated sunlight has been studied. Temperature coefficients of maximum power were found out to have the tendency to decrease against increasing irradiation intensity, and the values were -0.44%/°C and -0.34%/°C under 1 sun and 25 suns respectively.
Temperature and irradiation intensity effects on other performance parameters such as open-circuit-voltage, fill-factor etc. are presented as well.
A 2 kW Photovoltaic Power Generating System Using a-Si Solar Cells
Authors: Nakano Shoichi , Shibuya Hisashi , Yokoo Toshiaki , Tsukamoto Kazuyoshi , Kuwano Yukinori
Published: March 2014

We have developed integrated amorphous silicon (a-Si) solar panels and have applied them to an electric power generating system. The integrated a-Si solar panel consists of 20 integrated type a-Si solar cell modules, each with a size of 10 cm ×10 cm, which have been developed for use in an electric power generating system. The power generating system is set in an experimental model house. The output performance of the solar panels has been measured, and a peak amount of 2 kW was obtained. The conversion efficiency decreased about 10% within one month and then became stable. This stability has continued until the present time. The initial degradation of the conversion efficiency mainly depends on the degradation of the fill factor. It has been confirmed that electric power generating systems using a-Si solar panels are already effective enough for practical use.
Conductivity Control and Photovoltaic Effects in Chalcogenide Amorphous Semiconductor
Authors: Okano Shuichi , Kawachi Ryuichi , Yamazaki Ryoichi , Kakimoto Yoshio , Suzuki Masakuni
Published: March 2014

We found that several metals with strong ionization tendency such as Mg, Al and Zn formed rectifying contacts with amorphous chalcogenide films. The rectifying effects are ascribed to a high-resistivity layer in contact region between such metals and chalcogenide films, which is considered to be formed by the diffusion of small amount of metal ions. We also found that the considerable amount of Cu and Cd diffused into amorphous chalcogenide films below the glass transition temperature in the dark so that conductivity of amorphous chalcogenide films increased drastically. In these phenomena, chemical reactions at the interface are considered to play important roles in the diffusion of metal ions into amorphous chalcogenide films. Metal doping assisted by chemical reaction would be useful and important for the application of amorphous chalcogenide semiconductors to photovoltaic devices.
Radiation Test of Silicon Solar Cells for Space Application
Authors: Matsuda Sumio , Hirano Taizo , Matsutani Toshinobu , Kiyota Yoshiharu , Saga Tatsuo , Uchida Yasunori , Sato Hiroshi
Published: March 2014

The degradation of electrical performance due to electron, high energy proton, and low energy proton irradiations was investigated for various space qualified modern solar cells. Electrical performance data taken under AMO/28°C conditions on the irradiated and annealed cells showed that conventional (Conv.) and BSR cells are the least sensitive to damage under high energy particle (electron and proton) irradiations. Black cells were more tolerant to the high energy particle irradiations than BSF cells, and showed the most excellent electrical performance among all types of solar cells after heavy irradiations.
Covered cells (Black and BSFR cells) were irradiated with low energy protons. The Voc and Isc degradations of the cells could hardly be found, while the Pmax degradations were about 5%.
Effect of the Deposition Condition on Properties of a-Si: F: H Films
Authors: Uchida Yoshiyuki , Ichimura Takeshige , Nabeta Osamu , Takeda Yukio , Haruki Hiromu
Published: March 2014

We prepared a-Si: F: H films from SiF4 and H2 mixture gas by three discharging methods (DC, CSDC, and RF). The fluorine concentrations for the DC, CSDC and RF films are 15 at.% 1.5 at.% and 0.5 at.%, respectively. Optical emission spectra from the discharging gas suggest that the kinetics of the chemical reaction on the substrate surface is essential for the film formation and the cathode screen considerably affects the plasma condition. Even 1.5 at.% incorporated fluorine atoms have the effect to reduce the optically induced conductivity change.
When the nondoped a-Si: F: H layer is deposited onto the doped film, considerable amount of doped atoms are incorporated in to the nondoped layer.
Amorphous Silicon Films Prepared by rf-Bias Sputtering
Authors: Suzuki Masakuni , Suzuki Makoto , Kanada Matahiko , Shimizu Shin , Takayama Yukiyoshi , Yamaura Tadashi
Published: March 2014

Amorphous silicon films were prepared using pure argon by rf-Bias sputtering with a magnetron target. The sample films involved a small amount of hydrogen which is considered to originate from adsorbed water vapour in the sputtering chamber. It was found that ion-bombardment caused the changes in IR absorption spectra and that film quality was improved by ion-bombardment. For bombarded samples photoconductivity reached ∼10-4 S/cm and the spin density associated with dangling bond centers was reduced to ∼1017 cm-3.
Preparation and Photovoltaic Characteristics of a-Si Solar Cells Produced by a Consecutive, Separated Reaction Chamber Method
Authors: Ohnishi Michitoshi , Nishiwaki Hidenori , Nakashima Yukio , Nakamura Noboru , Tsuda Shinya , Fukatsu Takeo , Kuwano Yukinori
Published: March 2014

A new fabrication process of a-Si solar cells is presented. This new process is called the consecutive, separated reaction chamber method, and the p, i and n layers can be separately deposited in different reaction chambers. It was confirmed by IMA measurement that the codiffusion and undesirable mixing of donor and acceptor dopants, which always exist in the conventional single reaction chamber, and which result in a deterioration of the cell performance, are clearly removed by the separated reaction chambers. The best conversion efficiency of p-i-n a-Si solar cells prepared by this new method is 8.15%.
Preparation and Properties of a-Si: H Solar Cells on Organic Polymer Film Substrate
Authors: Okaniwa Hiroshi , Nakatani Kenji , Yano Mitsuaki , Asano Mitsuo , Suzuki Kazutomi
Published: March 2014

The plasma deposited a-Si: H p-i-n/ITO heteroface solar cell on flexible organic polymer substrate has been studied on the photovoltaic properties and their dependence on the deposition temperature and surface morphology of a-Si: H layer. So far, the conversion efficiency of 6.36% was obtained for the cells on the polymer film substrate by utilizing microcrystalline n-layer instead of amorphous n-layer. This figure is a little lower than that of cells on stainless steel plate and is partly attributed to the larger surface roughness of a-Si: H on organic polymer film.
Amorphous Solar Cells Using a-Si: H and a-SiGe: H Films
Authors: Nakamura Genshiro , Sato Kazuhiko , Yukimoto Yoshinori
Published: March 2014

The electric properties of optimized a-SiGe: H films deposited by an R.F. glow discharge in (SiH4+GeH4) and application of these films to the tandem type solar cells were investigated. The dark-conductivity of a-SiGe: H films increase with increasing Ge content and follows quite well to the Meyer-Neldel rule with measured activation energies. Fermi level which was deduced from the activation energy shifts toward mid-band gap under the optimized growth condition. The ratio σph/µn which is related to the lifetime of photogenerated carriers was found nearly constant for various Ge contents in the a-SiGe: H films.
Inverted P-I-N type amorphous solar cell with an intrinsic a-SiGe: H film shows higher spectral response in the red region than other kind of a-Si: H aolar cells. The highest conversion efficiency of 8.5% has been obtained by the three junctions stacked cell composed of two inverted a-Si: H P-I-N cells and one inverted P-I-N cell with an intrinsic a-SiGe: H film.
Plasma Hydrogenation Effects in Cast Polycrystalline Silicon Solar Cells
Authors: Noguchi Kesao , Saito Takeshi , Shimura Akio , Ichikawa Shoji
Published: March 2014

Hydrogen plasma treatment of polycrystalline silicon is performed to eliminate the detrimental effects of grain boundaries and grain itself on solar cell performances. Cast polycrystalline silicon solar cell reached a 13.9% photovoltaic conversion efficiency after hydrogenation. Efficiency improvement ratios after hydrogenation have various values, ranging from 3 to 76%
on the same grain size samples. It is shown that grain boundary hydrogenation effects are small and crystalline grain performance itself is greatly improved by the plasma treatment. The grain hydrogenation effect may be attributed to the vanishing of the unintentionally introduced carbon impurity defect.
Large Area Si Sheet Prepared Using Spinning Method
Authors: Maeda Yasuhiro , Yokoyama Takashi
Published: March 2014

Polycrystalline silicon sheets having a 150 mm diameter or 100 mm square with thicknesses of 0.3 to 0.4 mm have been obtained directly by spinning the silicon melt dropped on the plate. A production time of the sheet formation from the melt is about one second per sheet. The crystallites of the sheet have columnar structures. Material loss in the production process is little or none because of a clean recovery of the surplus silicon. Using this sheet, p-n junction solar cells with AMI efficiencies of 5.8 to 6.1% have been made experimentally.
Efficiency Improvement of Solar Cell utilizing Plasma-deposited Silicon Nitride
Authors: Morita Hiroshi , Sato Akira , Washida Hiroshi , Kato Taketoshi , Onoe Akira
Published: March 2014

Plasma-deposited silicon nitride films prepared by plasma CVD or reactive magnetron sputtering were studied as antireflective coating for various solar cells. Remarkable improvement of performance was found in case of n+/p cells using single crystalline substrate with texturized surface and polycrystalline substrate. These are due to nitrogen atoms contained in the AR coating, which diminish the surface recombination velocity in two ways. One is the effect of the retarding field for minority carriers built in near surface of silicon by the aid of space charge in AR coating, and the other is the result of an inactivation of recombination centers such as dangling bonds or of trapping levels existing at grain boundaries or surfaces of silicon.
Polycrystalline and Amorphous Si MOS Solar Cells by Anodization
Authors: Yamamoto Hidekazu , Moniwa Masahiro , Hasegawa Hideki
Published: March 2014

Anodization in various modes for fabrication of polycrystalline and amorphous Si MOS solar cells is investigated. Anodization is found to be very effective for increasing the open-circuit voltage without reducing photocurrent. It is also found that anodized polycrystalline and amorphous Si surfaces give very much improved yields of successfully operating cells as compared with chemically polished surfaces. The mechanism is explained in terms of passivation of material defects in poly-Si and a-Si by selective anodization.
Poly-Si and a-Si: H MOS Photodiodes for Large-Area, High Spatial Resolution Photosensor Arrays
Authors: Moniwa Masahiro , Arimoto Satoshi , Hasegawa Hideki
Published: March 2014

Performances of poly-Si and a-Si: H MOS photodiodes produced by anodization are investigated. It is shown that these anodized MOS photodiodes posses high reverse breakdown voltage, high speed and acceptable sensitivity as compared with those of single-crystal Si pho-todiodes and a-Si: H p-i-n photodiodes. Enhancement of the reverse breakdown voltage and yields by anodization is achieved, and it is related to selective passivation of material defects by anodization. Such poly-Si and a-Si: H MOS photodiodes appear promising for application in largearea functional photosensor arrays with high spatial resolution.
Characteristics of Silicon Solar Cells Fabricated by Non-Mass-Analyzed Ion Implantation
Authors: Itoh Haruo , Tokiguchi Katsumi , Saitoh Tadashi , Tamura Masao , Tokuyama Takashi
Published: March 2014

Silicon solar cells are fabricated by non-mass-analyzed ion implantation using 100% PH3 discharge gas. The energy conversion efficiency of cells fabricated by implantation at 5–10 keV is 10% without anti-reflection coating. Cell efficiency decreases as ion energy or total ion dose is increased. This decrease in cell efficiency is attributed to the detrimental effect of H+ ion. This is mainly because the damage created by co-implanted H+ ions is not completely annealed out.
Photoacoustic Spectra of CdS: Cu by Piezoelectric Transducers
Authors: Morimoto Jun , Ito Takamichi , Miyakawa Toru
Published: March 2014

Photoacoustic (PA) spectra of undoped and Cu doped CdS single crystals are measured using both PZT and ZnO transducers and are compared with PL emission spectra. PA spectra taken by PZT and ZnO transducers differ, especially in the longer wavelength region. The profile of the ratio of Cu to native center peaks in the PA signal along the direction of Cu diffusion shows a good correlation with the SIMS profile of Cu impurities concentration. Simplified thermal analysis seems to offer a reasonable account of the results.
Absolute Calibration of Acoustic Emission Transducers
Authors: Hatano Hajime
Published: March 2014

Some of the previous research on AE transducer calibration was reviewed briefly, and a few important problems in the calibration which seemed to have been overlooked were discussed. A novel system which employed a large hammeredsteel block as the sound medium for precise calibration was outlined. Absolute sensitivity and its frequency characteristics were determined in Rayleigh- and longitudinal-wave sound fields by a reciprocity technique.
Correction for Refraction on Ultrasonic CT
Authors: Itoh Takashi , Choi Jong-soo , Ksai Chihiro , Nakajima Masato
Published: March 2014

Degradations in attenuation images were evaluated by experiment using agar gel phantom and by computer simulation. As a result, it was determined that large errors on reconstructed attenuation constants are due to refraction of ultrasound. It was also confirmed that the influence of refraction can be corrected by measuring the maximum value of intensity distribution. Although this correction method is not completely accurate as reflection is not considered, it was proved to be practical from the results of the experiments and computer simulation.
Sound Fields of Ultrasonic Array Transducers
Authors: Mochizuki Takashi , Hirose Masanori , Kasai Chihiro
Published: March 2014

Electrical scanning ultrasonic diagnostic equipment enables us to observe B-mode images of soft tissues in real time. The defect of the system, however, is its large artifacts in the B-mode images, caused by the side lobes of an array transducer. This paper describes the theoretical calculations of sound fields of ultrasonic array transducers and the experimental results. The calculations are carried out for both a continuous wave and a pulse wave. The interval of array elements is very influential and the amplitude of the side lobe largely depends upon a distance between blocks of the elements and it becomes larger as the distance increases.
Numerical Reconstruction Systems from Acoustic Holograms Using the Backward Propagation Method
Authors: Nagai Keinosuke
Published: March 2014

In this paper a digital imaging system is studied in terms of an analog point spread function. The Fourier integral representation of the DFT is introduced and applied it to the backward propagation method to analyze a holographic imaging system. Then, without using the Fresnel approximation, A point spread function of the system is derived through which simple formal solutions for basic problems are obtained. Some experimental results are also displayed to demonstrate the discussion.
Ultrasonic Transducer of Piezoelectric Ceramic for Pulse Driving
Authors: Takayama Ryoichi , Tokushima Akira , Ueshiba Nozomu , Ise Yukihiko
Published: March 2014

An ultrasonic transducer of a bimorph-type piezoelectric ceramic, which is mainly used in air for measurement, has high sensitivity but slow transient response because of the high mechanical Q. The authors propose a new construction which consists of a bimorph-type piezoelectric ceramic, a conical diaphragm vibrating in a higher order mode and a damper controlling the mechanical vibration, and they have experimentally confirmed the best dimensions. A faster transient response transducer in air has been developed which has excellent temperature, environmental and aging characteristics.
Electrostatic Precipitation with Ultrasound Field
Authors: Nakane Tomoo , Otsuka Tetsuro , Seya Koichiro
Published: March 2014

One on the industrial applications of high power ultrasound is an agglomeration of very fine particles, and the authors have been working on this subject.
This paper reports on a pilot precipitator made with two units: one an electrostatic precipitation unit and the other a high intensity ultrasound unit. The two units were connected in series and gas density was measured in three circumstances: ultrasound unit operated, electrostatic precipitation unit operated and both two units operated.
As a result, sonic agglomeration reached a sound pressure level of more than 145 dB for the ultrasound unit. For the electrostatic precipitation unit, voltage up to 15 kV was applied and the higher the voltage, the higher the collection efficiency measured. When both units were operated at the same time, higher collection efficiency was obtained even when low voltage was applied to the electrostatic precipitation unit.
Ultrasonic Measurements Under Extreme Conditions. Part I. –Measurements at Ultralow Temperatures.
Authors: Ikushima Akira J. , Fujii Itsuhiro , Nara Koichi
Published: March 2014

With an emphasis on technical aspects, a description is given of an example of ultrasonic measurement at ultralow temperatures.
Ultrasonic Levitation and Positioning of Samples
Authors: Hatano Hajime , Kanai Yoshikazu , Ikegami Yuuji , Fujii Tsumoru , Saito Katsutoshi
Published: March 2014

Several problems on the levitation and contact-free position control of samples using ultrasonic energy were studied in development of an integrated positioning system for space processing. A method which employed a single ring-type radiator was proposed for multiaxial positioning with free access. Positioning in the standing wave field of a cylindrical tube was also studied. Finite element simulation was conducted to evaluate the magnitude and stability of the positioning force acting on a sample in a tube.
Visualization of Ultrasonic Waves by Schlieren Method
Authors: Negishi Katsuo
Published: March 2014

Principle and application of the schlieren method for the visualization of ultrasonic waves are described. Some schlieren photographs of continuous and pulsed ultrasonic waves are shown, and short interpretations of ultrasonic images are also given. It is emphasized that stroboscopic schlieren observation of reflecting ultrasonic pulses reveals their transient behaviors which are quite different from the result of continuous wave theory.
Numerical Calculations of Ultrasonic Fields of a Circular Piston and Its Representations by Contour Lines
Authors: Yamada Hisao
Published: March 2014

Using an improved numerical method to calculate the field of a piston radiator, precise contour maps of the CW field of a circular piston radiator is obtained. The result is compared with a transient field which is obtained by the fourier transformations of the CW fields.
Finite-Element Analysis of Acoustic Surface Waveguides Using Approximate Analytical Solutions
Authors: Koshiba Masanori , Okada Masaya , Hayata Kazuya , Suzuki Michio
Published: March 2014

An efficient finite-element program utilizing approximate analytical solutions is described for the analysis of thin-film weveguides and topographic waveguides for acoustic surface waves. In this method, the only substrate region for the thin-film waveguide and the only ridge region for the topographic waveguide are divided into elements, and therefore it is possible to use computer memory more economically. The results obtained agree well with the earlier theoretical and experimental results.
Reflection and Transmission of Rayleigh Surface Wave at a Surface Crack
Authors: Hirao Masahiko , Miura Yosuke , Fukuoka Hidekazu
Published: March 2014

Scattering of Rayleigh surface waves by a surface crack is numerically analyzed using the finite difference method and the FFT algorithm. For small cracks, the reflection coefficient increases and the transmission coefficient decreases with the depth/wavelength ratio, while the transit time of transmitted signal linearly increases with the ratio. The numerical solutions are in good agreement with the experimental observations by ultrasonic spectrum analysis and the transit time measurements for artificial cracks in mild-steel specimens.
Surface Acoustic Wave Parametric Oscillation
Authors: Nakagawa Yasuhiko
Published: March 2014

Theoretical and experimental results are reported for a parametric oscillation of surface acoustic waves in Si-on-LiNbO3. The threshold power required for parametric oscillation can be substantially reduced by the highly efficient surface acoustic wave reflectors. The conversion efficiency from pumping to the surface acoustic waves was -23 dB at the threshold power of 14.4 dBm.
Measurement of SAW Propagation Properties Using a Laser Probe
Authors: Yoneda Katsumi , Tawata Masahiro , Hattori Shuzo
Published: March 2014

Measurements of surface acoustic waves (SAW) propagation properties such as amplitude profiles and phase and group velocities on LiNbO3 have been done using a very stable and highly sensitive laser probe which is a type two-beam interferometer with minimum detectable SAW amplitude 8×10-3 Å at 56 MHz on 127.86° rotating Y-cut LiNbO3. Amplitude profiles are measured for two types of interdigital transducers (IDT) with ten parallel finger pairs and ten circular-arc finger pairs. Results of phase velocity measurements are shown on a table and compared with the literature1) for certain orientations of LiNbO3 or LiTaO3.
Electrical Characteristics in Al/ZnO/SiO2/Si Structure
Authors: Sakai Takamasa , Sato Yasuhiko
Published: March 2014

Al/ZnO/SiO2/Si structure is experimentally studied for application to SAW devices and other progressive devices. The good agreement between the experimental and theoretical value of Cac/Cinv shows that the high density interface states do not exist at the SiO2-Si interface of the Al/ZnO/SiO2/Si (MZOS) structure. It is found that hysteresis characteristics of the MZOS–C versus the gate bias depends on the voltage sweep rate and the resistivity of ZnO film. It is confirmed that the quasi-stable flat band voltage of the MZOS-C depends on the ZnO thickness and sputtering rf power.