bluuebunny/crossref_metadata_2025 huggingface dataset:
Bright Pure Green Emission from N-free GaP LED's
Authors: Nishizawa Jun-ichi , Okuno Yasuo , Koike Masayoshi , Sakurai Fumitoshi
Published: March 2014

The pure green emission with high external efficiency of 0.12% has been obtained in nitrogen free GaP LED grown by applying the optimum phosphorus pressure at a constant temperature solution growth. The high efficiency N-free LED has a p+n- structure and the peak emission wavelength is 5560 Å at room temperature. The minority carrier lifetime is 1.4 µsec. The crystalline quality has been improved under the optimum phosphorus pressure and the concentration of deep levels in GaP decreases. Therefore, the minority carrier lifetime becomes longer, and the high efficiency pure green GaP LEDs have been produced.
An Improved Etched Buried Heterostructure Laser with Reduced Threshold Current
Authors: Ayabe Masaaki , Matsuda Osamu , Dosen Masashi , Santa Sumio , Watanabe Naozo
Published: March 2014

An improved etched buried heterostructure laser was developed for optical read-out purposes. A curved active layer is formed in a V-shaped groove by a single run of the multi-layer LPE growing procedure on an etched substrate. A semiinsulating region to confine current in the lateral direction is formed by proton implantation.
A CW threshold current of 15 mA is the lowest attained with a cavity length of 200 µm. The transverse mode is usually fundamental. The single longitudinal mode operation is achieved at 1.2 times the threshold current. The far-field beam shows an aspect ratio of less than 2.5. The uncoated devices have catastrophic damage limit larger than 20 mW/facet in CW operation.
(Invited) Materials and Devices for Long Wavelength Optical Communication
Authors: Mizushima Yoshihiko
Published: March 2014

Features of the optical glass fibers in the long wavelength range are briefly mentioned. The present experimental transmission system is outlined. The systems are aiming at either long distance or high speed transmission. The present states of the art of important devices, lasers, LEDs, detectors and isolators are reviewed. Particularly long life has been attained. Peculiar features of GaInAsP alloy are discussed, considering the quaternary compositional freedom and the flexible nature of In-containing alloy. From the physical point of view, several proposals are given.
Thin Film Optical Circuit Fabrication Using a CO2 Laser
Authors: Terui Hiroshi , Kobayashi Morio
Published: March 2014

Film sputtered from SiO2 25 mol%–Ta2O5 75 mol% target presents a refractive index decrease up to 4.1×10-2 by CO2 laser irradiation. Some optical circuits such as mirror, branching circuit, channel waveguide have been fabricated using the index decrease phenomenon. In the experiment, the maximum reflecting angle is 11.5°. A typical
bent channel waveguide with 7.5 mm bent radius has a low propagation loss, 1.1 dB/cm at 0.633 µm wavelength. It is shown that the well-known ray equation is applicable to design the optical circuits.
Signal Processing with Nonlinear Integrated Optics
Authors: Normandin R. , Stegeman G. I.
Published: March 2014

We present here the integrated optics analog to the well-known surface acoustic wave convolver. Picosecond signal processing capabilities are achieved by the non-degenerate four wave mixing in a Ti in-diffused LiNbO3 waveguide. This second order interaction between two oppositely propagating guided modes was observed to generate a radiation field at the sum frequency into a direction normal to the waveguide surface during the pulse overlap. The potential applications of this phenomenon to processing functions such as convolution, time inversion etc., to precision timing and picosecond metrology, and to ultra-fast transient digitizers are discussed.
Preparation and Characterization of Reactively-Sputtered Amorphous Si: H Films
Authors: Iizima S. , Okushi H. , Matsuda A. , Yamasaki S. , Nakagawa K. , Matsumura M. , Tanaka K.
Published: March 2014

Amorphous Si: H films have been prepared by reactive sputtering of crystalline Si in Ar–H2 mixture, under various deposition conditions of substrate temperature and H2 concentration in sputtering gas, and their optical, structural and electronic properties have been mapped out for the first time. The obtained data have been compared with those of glow discharge a-Si: H film and discussed in a unified manner. It has been demonstrated that bonded H content, Si–H bond configuration, Ar content involved in the film and thermal history are main factors affecting optical and electronic properties. The H content associated with SiH as well as that with SiH2 has been calculated as a function of total H content assuming Poisson distribution, which has been compared with the experimental data.
Amorphous Silicon Image Pickup Devices
Authors: Imamura Yoshinori , Ataka Saburo , Takasaki Yukio , Kusano Chushiro , Ishioka Sachio , Hirai Tadaaki , Maruyama Eiichi
Published: March 2014

Reactively sputtered amorphous silicon film is used as a photoconductive target of the vidicon type image pickup tube. Variation of tube characteristics with the hydrogen partial pressure in the discharge gas during sputtering are investigated. The results indicate that hydrogenated amorphous silicon films prepared in hydrogen partial pressures of 1∼2×10-3 Torr are suitable for image pickup tubes. This amorphous silicon vidicon has several excellent characteristics: better sensitivity of about twice that of the conventional tubes, high resolution, little after-image, and no blooming.
High Density Video Signal Recording in a New Amorphous Chalcogenide Thin Film
Authors: Terao Motoyasu , Shigematsu Kazuo , Ojima Masahiro , Taniguchi Yoshio , Horigome Shinkichi , Yonezawa Seiji
Published: March 2014

Tellurium-based compound thin films which contain arsenic as the second component element are found to have high performance for optical video recording. The required incident argon-ion laser-beam power is about 10 mW for recording in an As–Te system thin film on a polymethyl-methacrylate (PMMA) disk with a cellulose acetate (CA) surface coating rotating at 1800 min-1. Addition of Se to the As–Te system thin film greatly increases film stability. A signal-to-noise ratio of about 45 dB is obtained in reproduced color video signals.
Low-frequency Low-noise Transistors Fabricated by Double Ion Implantation
Authors: Yagi K. , Tamura M. , Yanagi Y. , Inaniwa K. , Tokuyama T.
Published: March 2014

A two-stage annealing process composed of first-stage low-temperature wet-oxygen oxidation and second-stage high-temperature dry-nitrogen drive in is proposed to fabricate double-implanted low-frequency low-noise npn transistors. Emitter edge dislocations and surface contaminations such as SiC particles are eliminated by the two-stage annealing process, and the double-implanted transistors having the equivalent noise voltage at 10 Hz of 12 nV/√Hz and the linearity in collector current dependence of h
FE of 0.9–0.95 are achieved. Uniformity in h
FE within ±5% are obtained by the optimization of first-stage low-temperature wet-oxygen oxidation process.
(Invited) Advances in Silicon Crystal Properties
Authors: Huber D. , Sirtl E.
Published: March 2014

The defect situations as they are presented in different categories of silicon material are briefly described. It is stated that oxygen or carbon are predominant factors in forming localized defects. After a brief introduction into lattice kinetics of gettering, different aspects of defect engineering are discussed. For dislocation-free crystals, this article mainly concentrates on the kinetics of two types of defects: oxygen swirl and haze. Substantial efforts to prevent their formation in the surface region of the wafer by applying either internal or external gettering methods have been made more recently. The special nature of polycrystal-line silicon solidified from the molten state, finally represents a different system of internal gettering.
Doping Profile Control in Si MBE Film with Sb Ion Doping
Authors: Sugiura Hideo
Published: March 2014

Arbitrary doping profiles with abrupt transitions have been produced in Si MBE films by means of Sb ion doping. The ion doping could control the doping level in the films over the range 1016–1020 cm-3. The accuracy of controlling the doped layer thickness was within a couple of 100 Å. The doping levels of the doped Sb determined by neutron activation analysis, backscattering measurement, and four point probe technique were all in good agreement. It was also found from the doping profiles determined by the three measurements that the Sb atoms doped by the ion doping did not segregate to the surface of the epitaxial film.
GaAs and GaP Amorphous-Film/Crystal Junctions
Authors: Kumabe Kenji , Matsumoto Nobuo
Published: March 2014

Amorphous thin films of GaAs, GaP, and gallium phosphide-hydrogen alloy(a-GaP(H)) were deposited on crystal GaAs by sputtering in argon or in a mixture of 90 mol.% hydrogen and 10 mol.% argon, and amorphous-film/crystal junctions were fabricated. The current-voltage characteristics of the junctions indicate that the a-GaAs and a-GaP films sputtered in argon and the a-GaP(H) film are p-like. An injection type electroluminescence has been observed in the amorphous-film/crystal junctions. It is concluded from the spectra that minority carrier injection from the amorphous film to the crystal occurs and radiative recombination is observed in the side of the crystal. The quantum efficiency of the a-GaP(H)/c-GaAs surface-emitting diode is estimated to be 10-5.
Photovoltaic Effect of Amorphous InxSe1-x Film–SnO2 Structure
Authors: Matsushita Tatsuhiko , Suzuki Akio , Okuda Masahiro , Sakai Takashi
Published: March 2014

This paper describes the photovoltaic effect on the system of metal electrode–amorphous In
x
, Se1-x
film–SnO2 layer. The electrode-material dependence, the annealing effect and the temperature dependence were investigated. For the system of x=0.2, the maximum efficiency of about 2.8% was obtained at 105°C. A tentative band model for a consistent explanation of the experimental data is proposed.
Electron-Beam Deposited SnO2/a-Si(H) Photovoltaic Device
Authors: Murayama Jin , Kawajiri Kazuhiro , Mizobuchi Yuzo , Nakajima Yosuke
Published: March 2014

A SnO2/a-Si(H) heterojunction photovoltaic device was fabricated by electron-beam deposition of tin oxide on glow discharge deposited amorphous hydrogenated silicon, and the I-V characteristics were measured under illumination. The photovoltaic energy conversion efficiency depends on the angle (θ) which the SnO2 vapor stream makes with the normal to a-Si(H) film, and on the heat treatment in air after deposition. In our experiments at θ=40°with two hours treatment at 300°C, a photovoltaic energy conversion efficiency of 1.4% has been attained under the illumination of 65 mW/cm2 of an AM1 filtered Xe lamp. The optical gap and electrical conductivity of tin oxide film change with θ and heat treatment. It seems that as-deposited tin oxide film is extremely oxygen-deficient and with heat treatment in air it oxidizes to be almost stoichiometric SnO2.
Low Temperature Synthesis of CdTe and Its Application to CdS/CdTe Solar Cell
Authors: Nakayama Nobuo , Matsumoto Hitoshi , Nakano Akihiko , Ikegami Seiji
Published: March 2014

It has been found that CdTe can be synthesized from a paste consisting of Cd powder, Te powder and propylene glycol (binder) in N2 atmosphere at a temperature lower than 300°C. The reaction synthesizing CdTe from the paste begins at about 180°C. This method is also effective for lowering the sintering temperature of CdTe film. We can lower the sintering temperature of the CdTe film down 600°C. The new method of the CdTe synthesis is applied to the preparation of thin film CdS/CdTe solar cells with the screen-printing technique. The cell has an intrinsic conversion efficiency of 4.7%.
Problems in Growth of 4-Inch Wide Silicon Ribbon Crystals
Authors: Matsuda Masatoshi , Kuroda Ekyo
Published: March 2014

Ribbon crystals with 4-inch width are grown using a specially designed rectangular heater. Wide ribbons crack spontaneously during crystal growth or handling. Thermal stress in crystals is calculated using the observed temperature distribution in crystals. It is clarified that larger maximum shear stress is concentrated around the center of the crystal in wider ribbons. Local thermal stress leads to residual stress, which is the main reason for spontaneous cracks in these ribbons.
Simple Method for the Determination of Series Resistance and Maximum Power of Solar Cell
Authors: Warashina Masatoshi , Ushirokawa Akio
Published: March 2014

A simple method is proposed to determine the series resistance R
s and the perfection factor n of solar cells from the measurement of the tangents to the current I–voltage V curve at constant light intensity. The values of R
s and n thus determined are then used to predict the maximum power P
m and the voltage V
m at which the power gets maximum. This new method is applied successfully to the conventional cell, BSF (Back Surface Field) cell and the textured BSF Si cell. A good agreement is obtained between the calculated- and the directly measured values of V
m and P
m.
Low Cost Production of Terrestrial Solar Arrays Utilizing EFG Silicon Ribbon Crystal
Authors: Kimura Kenjiro , Koyama Shizuo , Watanabe Hiroyuki
Published: March 2014

A new production line has been investigated for low cost terrestrial solar arrays using EFG silicon ribbon crystal. This paper describes the recent technical progress on EFG ribbon growth, wafer fabrication process for silicon ribbon, electrical output performance of ribbon solar cells and modules and also commercial solar arrays.
EFG silicon ribbons with 50 mm width and 0.3∼0.5 mm thickness are grown continuously up to 50 meters long. Semi-automatic growth operation with ribbon width control by utilizing TV camera watching system is developed to achieve simultaneous and stable production from several growth stations. From this ribbon, 50×76 mm large area rectangular solar cells are successfully produced using screen printed metallization technology with an average conversion efficiency of 8%.
Improved Efficiency of Si MOS Solar Cell due to Surface States and Oxide Charges
Authors: Katsube Teruaki , Umezaki Shigeo , Ikomat Toshiaki
Published: March 2014

The effects of interface states and fixed oxide charges on a MOS solar cell operation are theoretically analyzed and optimum design condition is deduced. In a p-MOS cell, negative fixed charges or acceptor type surface states with small hole capture cross section and large tunneling capture cross section are found to be effective to improve the efficiency due to the enhancement of the built-in voltage, while give negative effects in an n-MOS cell. However, efficiency improvement rate by surface states is also found to be rather smaller than that by fixed charges. The obtained maximum improvement factor as compared with the corresponding Schottky diode is 2.25 at the fixed surface charge density of 3×1012 cm-2 and the oxide thickness of 12 Å.
Silicon Solar Cells Fabricated by Ion Implantation and Laser Annealing
Authors: Itoh Haruo , Tamura Hiroshi , Miyao Masanobu , Warabisako Terunori , Itoh Kazuo , Sasaki Yoshitomo
Published: March 2014

Silicon solar cells are fabricated using ion implantation and laser annealing. An AM1 conversion efficiency of 10.5% is obtained without an antireflection coating in a cell ion-implanted with 4×1015 P+ ions/cm2 at 25 keV and laser annealed using a Q-switched ruby laser. This efficiency increases after low temperature furnace annealing as a result of improvement in open circuit voltage (V
oc) and fill factor (FF).
The dependence of V
oc on furnace annealing temperature is examined by diode characteristics measurements and deep-level transient spectroscopy. The fact that V
oc increases and diode reverse current density decreases as the furnace annealing temperature increases is related to the decrease in the number of residual defects near the junction.
High Performance BSF Silicon Solar Cell with Fire Through Contacts Printed on AR Coating
Authors: Nunoi Tohru , Nishimura Nobuo , Nammori Takayuki , Sawai Hiroyasu , Suzuki Akio
Published: March 2014

A high performance cell using especially compounded paste was fabricated as follows: First, excellent anti-reflection coating and shallow junction were formed at the same time with a phosphoric-titanate compound solution spun on etched surface. Then, BSF forming was done by an aluminum paste. A silver paste on the front side and an aluminum-silver paste on the rear were fired simultaneously.
As a result, the front paste punched through the TiO2 layer. The conversion efficiencies of 13 %(AMO) and 16%(close to AM2) have been obtained for the 75 mmφ cell without additional treatment such as a solder-dipping.
Life Tests of SnO2/n-Si and ITO/p-Si Solar Cells
Authors: Nagatomo Takao , Katsuta Shiro , Omoto Osamu
Published: March 2014

The SnO2/n-Si and the ITO/p-Si heterojunction solar cells remain stable over 2 year's time onshelf. The degradation is enhanced at elevated temperatures for SnO2/n-Si devices. The series resistances increase 30–230% for SnO2/n-Si devices stressed at a temperature of 150°C for 264 hours in an air. It is concluded that the degradation results from the growth of a semiinsulating interfacial layer (probably SiO2) between the SnO2 and the Si. ITO/p-Si devices are relatively stable as compared to SnO2/n-Si devices. A clue to the stability of ITO/p-Si devices comes from chemical free energies of formation for In2O3, SnO2 and SiO2.
Doping Effects of Group-III and -V Element on a-Si Prepared by High Pressure rf Sputtering
Authors: Suzuki Masakuni , Nakao Akira , Maekawa Toshikazu , Kumeda Minoru , Shimizu Tatsuo
Published: March 2014

Doping effects of group-III and -V element on the a-Si films prepared by “high” pressure rf sputtering were studied. Three different types of doping effects on conductivity were observed for different elements. One is the increase of conductivity due to the shift of the Fermi level, another is the increase of conductivity due to the increase of hopping sites contributing to variable range hopping conduction and the third is that doping is less effective on conductivity. Distinct adsorption effects on conductance were observed for the cases of B- or Al-doping. These phenomena indicate that the band-bending is caused in surface regions by adsorbates because of a relatively small density of localized gap states, so the formation of built-in potential due to Schottky barrier or p-n junction would be possible for those a-Si films prepared by “high” pressure rf sputtering.
Preparation and Optical Properties of ZnIn2Se4 Crystals
Authors: Trykozko R. , Filipowicz J.
Published: March 2014

Absorption edge, photoresponse, and reflectance measurements have been carried out on ZnIn2Se4 crystals grown by means of chemical transport reactions. Indirect and direct energy gaps were determined as E
gi=1.74 eV and E
gd=1.92 eV at LNT. Reflectance measurements have been done in the 1.5–25 eV energy range. The Kramers-Kronig analysis has been performed and optical constants of studied semiconductor have been claculated. Reflectance data (R) and calculated imaginary part (ε
2) of dielectric function allowed to make some conclusions about interband transitions. Singularities in R, ε
2 and valence electron concentration per atom (neff) were basis for conclusion that d band–conduction band transitions at energy about 12.5 eV have been observed.
Fundamental Optical Absorption in Crystals of the CdIn2S4–In2S3 System
Authors: Nakanishi Hisayuki , Endo Saburo , Irie Taizo
Published: March 2014

The optical absorption edge has been measured at 92 K and 300 K on the single crystals of the system CdIn2S4–In2S3. The optical transitions for the edge absorption are of allowed indirect type for all the compositions and the energy gaps have a continuous change in compositional dependence. Thermoabsorption measurement was made on In2S3 single crystal and it was confirmed that In2S3 has indirect band gap of 1.98 eV associated with phonon energy of 0.03 eV. An investigation of the anisotropy of magnetoresistance has also been made at 300 K on single crystals of n-type In2S3. It is proposed for CdIn2S4 that the minimum of the conduction band is at k=0 and the maxima of the valence band are not at k=0 and that the structural defects introduced in the tetrahedral sites in the spinel lattice have no significant influences on the band structure.
Application of InGaAsP and AlGaAsSb for Optical Fiber Transmission
Authors: Furukawa Yoshitaka
Published: March 2014

Brief review on semiconductor lasers and avalanche photodiodes at long wavelength region is presented, in which emphasis is upon the temperature dependence of threshold current and the life for InGaAsP lasers and the noise characteristics for APD's.
The Influence of Alloy Scattering on Electrons and Holes in In1-xGaxAsyP1-y
Authors: Adams A. R. , Hayes J. R. , Greene P. D.
Published: March 2014

The mobility of electrons, µe, and holes, µp, in epitaxial layers of In1-x
Ga
x
As
y
P1-y
grown lattice matched to InP are presented as a function of composition, of temperature and of pressure. A strong downward bowing in µe and µp is observed as a function of y at room temperature. The temperature, T, variation of µe and µp shows that ionized impurity scattering is light but a strong scattering proportional to T
-1/2 exists. The pressure variation of µe indicates that this is due to alloy scattering rather than to space-charge scattering. The alloy scattering potentials Δ
U
e in n-type, and Δ
U
p p-type material both reach a maximum near the centre of the alloy range where Δ
U
e≃0.7 eV and Δ
U
e≃0.3 eV. A simple model suggests Δ
U
p may be associated with fluctuations in the ionization potential, while Δ
U
e may be associated with band gap fluctuations.
Photoconduction in Cd1-xMnxTe
Authors: Yamada K. , Lindström M. , Heleskivi J. , Galazka R. R.
Published: March 2014

The photoconductivity has been studied in the semimagnetic semiconductor Cd1-x
Mn
x
Te in the temperature region 4.2–300 K and in the spectral interval 0.6–2.5 eV. The content of the magnetic Mn2+ ions in the measured single crystals was x=0.05, 0.30 and 0.50. The forbidden gap E
g determined from the intrinsic peak position in the spectral dependence of the photosensitivity showed a normal blue shift down to 4.2 K in all crystals. The E
g values extrapolated to T=0 were E
g(x=0.05)=1.64 eV, E
g(0.30)=2.04 eV and E
g(0.50)=2.24 eV. In external magnetic fields up to 8 T a red shift of E
g was found. An acceptor level responsible for both of the dark conductivity and the sensitizing of the photoconductivity was found 0.15 eV above the valence band in the x=0.05 crystal. The acceptor was found to become deeper with increasing Mn content.
Theory of Antiferromagnetic Superconductors in Rare Earth Ternary Compounds
Authors: Machida Kazushige
Published: March 2014

Superconductivity coexisting with antiferromagnetism in rare earth ternary compounds is discussed theoretically. Two effects of spatially periodic antiferromagnetic molecular field and of spin fluctuations on conduction electrons are taken into account. It is shown that the characteristic dips of the upper critical field H
c2 near the Néel temperature in (RE)Mo6S8 (RE=Gd, Tb and Dy) can be explained by the present theory, and the latter effect is important to interpret H
c2(T) of SmRh4B4.
Anomalies in Ultra-High-Field Magnetic Superconductors (Eu1-xSnx)Mo6S8
Authors: Isino Masahiro , Kobayashi Norio , Muto Yoshio
Published: March 2014

Resistive behavior of three series of Chevrel phase, (Eu1-x
Sn
x
)Mo6S7, (Eu1-x
Sn
x
)Mo6S6.75 and (Eu1-x
Sn
x
)0.9Mo6S6.75, is studied in magnetic fields up to 90 kOe at temperatures down to 50 mK. Compounds with x>0.4 are usual ultra-high-field superconductors, while (Eu0.9Sn0.1)0.9Mo6S6.75 is a simple magnetic superconductor. Resistive behavior of the compounds between the above mentioned two sides is complicated, varying with the composition. For example, in (Eu0.8Sn0.2)Mo6S7 the resistance at high fields keeps roughly constant and the temperature dependence of H
c2 defined as a half of the resistance in the normal state is quite different with that defined at the appearance of the resistance. In (Eu0.85Sn0.15)Mo6S7 the superconductivity (=zero resistance) seems to reappear at high fields and at low temperatures.
Dielectric Constant and Its Temperature Dependence of LiInSe2
Authors: Kamijoh T. , Nozaki T. , Kuriyama K.
Published: March 2014

The dielectric constant of LiInSe2 and its temperature dependence were determined from capacitance measurements. The dielectric constant is 9.4 at room temperature. The value is discussed with the relationship of ε(0)=1+(\hbarωp/E
g)2. The dielectric constant varies linearly with temperature in the temperature range between 77 and 300 K. The dielectric constant extrapolated linearly to 0 K is 8.8. The temperature coefficient λ(=ε(0)-1dε/dT) is 2.3×10-4 K-1.
Flux Growth and Characterization of Multinary Phases in the CuGaTe2-ZnTe System
Authors: Garbato L. , Ledda F. , Manca P.
Published: March 2014

Phase relationships in the CuGaTe2–ZnTe system have been investigated in order to establish the growth techniques for the relative quaternary phases. A number of single crystals of Cu2(1-x)Zn4x
Ga2(1-x)Te4 composition has been grown by using ZnCl2 as flux material. The best growth conditions are: molar ratio flux to solid 20: 1; cooling rate, above 700°C, 3°C hr-1. All crystals behave as p-type semiconductor. The analysis of absorption and reflection spectra give evidence for a heavy doping of crystals. The direct gaps evaluated for crystals of composition CuZn6GaTe8 and CuZn8GaTe10 are respectively E
g=1.49 eV and E
g=1.56 eV at room temperature.
Growth and Characterization of CuInTe2 Single Crystals
Authors: Haworth L. , Tomlinson R. D. , Al-Saffar I. S.
Published: March 2014

A vertical Bridgman technique has been used to grow single crystals of the chalcopyrite semiconductor CuInTe2. Hall effect and resistivity data has been obtained over a range of temperature for several as grown and doped samples.
Vapor Growth of CuInS2 Single Crystals and Its Thermodynamic Considerations
Authors: Sun Cherng-yuan , Hwang Huey-liang , Leu Chung-yieh , Liu Lu-ming , Tseng Bae-heng
Published: March 2014

Single crystals of CuInS2 were grown by the closed tube chemical vapor transport method, using iodine as the transport agent. The charge zone was held at 800°C, while the optimal growth zone temperature was found to be in the range of 740–750°C. The shape and the size of the as-grown crystals were affected by the impurity adding and by the temperature difference between the two zones.
The transport rate of the growth process has been examined on the basis of thermodynamics. The theoretical values are verified by the experimental results, except for some explicable deviations. The transport rate shows a maximum as a function of iodine concentration.
About Defined Compounds in the Cu–In–Se System
Authors: Djega-Mariadassou C. , Rimsky A. , Lesueur R. , Albany J. H.
Published: March 2014

From the back reflexion X-rays diagrams, two defined compounds were evidenced in the copper deficient region in the Cu–In–Se system, (a) A cubic phase (a=11.533(1)Å) belonging to the space group P 4̄3 m, in which the atomic positions were refined on the basis of the formula Cu8In18Se32. A possible electronic disorder of 1.75% cannot be ruled out leading to the formula Cu8.5In18.5Se32. (b) A quadratic phase corresponding to Cu7In19Se32, with a=11.511(1)Å and c=11.503(2)Å. A paracrystalline region was found between these two defined compounds.
High Speed 4 kbit Static RAM with Silicide Coated Wiring
Authors: Morimoto Mitsutaka , Sugimoto Masunori , Terada Kazuo , Takahashi Kazukiyo , Ishijima Toshiyuki , Muta Hiroki , Suzuki Shun-ichi
Published: March 2014

A high speed, fully static, and 4096 word by one bit Random Access Memory has been developed, using short channel MOSFETs with platinum silicide (PtSi) coated polysilicon gate and PtSi coated n+ diffusion layer as low resistive wiring. The present RAM was operated on a single 5±1 volt power supply. Its typical performances are 21 nsec address access time, 23 nsec chip select access time, 500 mW operating power and 50 mW stand by power.
A High Performance I2L Compatible with Subnanosecond ECL Devices
Authors: Hirao Tadashi , Kijima Koichi , Murakami Kenji , Sakurai Hiromi , Akasaka Yoichi , Nakata Hidefumi
Published: March 2014

This paper describes a new approach for realizing a high performance I2L and a subnanosecond ECL circuit simultaneously on a single chip. Significant features of such a technology are a buried base structure for I2L gate and an implanted self-aligned contact (ISAC) structure for ECL circuit combined with dielectric isolation technology. The contributions of device parameters to the I2L characteristics are analyzed to get high speed operation.
Following typical data of these advanced structures on a same chip are obtained with optimizing process parameters for a 4 µm design rule; (1) a maximum toggle frequency of I2L flip-flop circuit is 95 MHz with an average power dissipation of 185 µW/gate, (2) a power-delay product of I2L gate is 45 fJ for the fan-out of 3 at injector current of 1 µA/gate, and (3) ECL gate delay time of 0.68 nsec is obtained with switching current of 0.46 mA on a same chip.
Improvement in CZ Silicon Wafer by Reducing Oxygen Impurity
Authors: Hoshikawa Keigo , Kohda Hiroki , Ikuta Kenji
Published: March 2014

Effects of oxygen and carbon impurities and various annealings on thermally induced defects and on MOS device performance were investigated by using selected silicon wafers with various oxygen and/or carbon concentrations and with distinct thermal history in growth process.
It was found that the thermally induced defects were strongly dependent on oxygen concentration, while carbon concentration hardly affected on them. No thermally induced defects were detected after being annealed at 1000°C for 12 hours in wafers with less than 4×1017 atoms·cm-3 oxgen concentration. Degradation in device characteristics was caused by thermally induced defects due to oxygen impurity. Oxygen reduction in CZ silicon wafer was a promising method to improve MOS device performances.
(Invited) SQUIDs as Potential Elements in Josephson Computers
Authors: Hasuo Shinya , Suzuki Hideo , Imamura Takeshi , Yamaoka Toyoshi
Published: March 2014

This paper presents superconducting quantum interference device (SQUID) type Josephson tunnel junctions for digital applications. Memory and logic circuits using SQUIDs are introduced and some new SQUIDs are described. Josephson computers of the future are also discussed.
V-Bipolar Device Utilizing Built-in Stress Gradient
Authors: Kanda Yozo
Published: March 2014

A new bipolar device utilizing built-in stress gradient caused by V-groove is proposed. The V-grooves are formed in the interdigital or stripe type transistors so that the band gap in the base becomes narrower than that in the emitter when compression is applied by bonding the pellets onto Cu headers because of thermal expansion difference. The band gap change caused by the V-groove is calculated. This band gap gradient greatly increases the downward and/or upward common emitter current gain.
A preliminary experiment was performed with a specially arranged transistor stressed by a sapphire stylus. The upward current gain was increased by a factor of 1000 with stress.
(Invited) Recent Progress in Amorphous Silicon Research and Photovoltaic Applications in the U.S.A.
Authors: Stone Jack L.
Published: March 2014

The recent achievements in the amorphous silicon area indicate a near term, low cost potential for commercialization of solar cells for remote and residential applications. The status of the research program being managed by the Solar Energy Research Institute (SERI) and other contributing programs will be reviewed. Technical problem areas will be addressed and new areas of interest will be briefly discussed.
Performance of 1 kWp AIGaAs/GaAs Terrestrial Concentrator Solar Cell Array
Authors: Yoshida Susumu , Mitsui Kotaro , Oda Takao , Yukimoto Yoshinori , Shirahata Kiyoshi
Published: March 2014

A 1 kWp (electrical output power at 100 mw/cm2 incident power density) concentrating photovoltaic array with 180 square Fresnel lenses and AIGaAs/GaAs concentrator solar cells has been constructed. The AIGaAs/GaAs concentrator solar cells consist of p-AlGaAs/p-GaAs/n-GaAs with an area of 2×2cm2. The p-GaAs layer thickness is set at 3–5 µm so as to keep the spreading resistance low. The concentrator cells are passively cooled by natural convection. The maximum output power from the best concentrator cell is 9.1 W with the efficiency of 22.6% at about 125 suns. The array output power of 977 W (I
sc=8.4 A, V
oc= 184 V, FF=0.632) has been obtained at 125 suns.
Design and Performances of a Triple (GaAs, Si, and Ge)- Solar-cell System with Multi-layered Spectrum Splitters
Authors: Sakaki Hiroyuki , Tanoue Tomonori , Yokoyama Koji , Sun Dian Chau , Sekiguchi Yoshinobu , Yukimoto Yoshinori
Published: March 2014

Calculation has been performed to predict the ultimate conversion efficiency of various split-spectrum multiple-solar cell systems. Based on this analysis, a triple-cell system is designed and fabricated, in which the solar radiation is divided by multi-layered filters into three beams of different spectral bands; the beams are then converted separately by GaAs-, Si-, and Ge-cell. The total conversion efficiency of 22.7% is achieved. The factors determining the efficiency are examined to clarify possible methods of attaining higher efficiencies.
Study of Photovoltaic Cells using Merocyanine-dye Thin Films
Authors: Kudo Kazuhiro , Shinohara Toshiro , Moriizumi Toyosaka , Iriyama Keiji , Sugi Michio
Published: March 2014

The spectral sensitivity of the organic diodes with merocyanine dye films was controlled in the visible spectral range by choosing proper dye molecules, or mixing two or three dyes. The photovoltaic cells with the layered structure of ZnO and merocyanine dye exhibited improved photovoltaic properties compared to the Al/day/Ag cell reported before. An electron diffraction study revealed that the dye films evaporated on the ZnO layer show a weak crystallization, while the dye films on an Al film are amorphous.
Photovoltaic Properties of Lead Phthalocyanine Contacts
Authors: Kanayama Seiji , Okuyama Naoki , Yasunaga Hitoshi
Published: March 2014

Measurement was made of the spectral sensitivity of the short-circuit photocurrent in lead phthalocyanine (PbPc) film cells sandwiched between several varieties of electrode materials. It was deduced from the spectral sensitivity of thick cells with thickness of the PbPc film more than 1 µm that the magnitude of the barrier height φ in the contact was in the following order;

φ(PbPc-Al)>φ(PbPc-SnO2)>φ(PbPc-Au)>φ(PbPc-In2O3).

All of these barriers bend downward in the PbPc toward each contact. The maximum spectral sensitivity was observed to be 2.4 mA/W in the cell In2O3/PbPc/Al. To improve the sensitivity, thin cells with thickness around 0.1 µm were prepared and examined with the result of unexpectedly low sensitivities in the cells with Al electrode.
Effects of Surface Conditions of Substrates upon Performance of a-Si Photovoltaic Cells
Authors: Kuwano Yukinori , Fukatsu Takeo , Imai Terutoyo , Ohnishi Michitoshi , Nishiwaki Hidenori , Tsuda Shinya
Published: March 2014

The growth process of a-Si film deposited onto an ITO substrate by a glow discharge reaction in SiH4 was investigated by transmission electron microscopy. The a-Si film grows to form an island structure at the first step (0–200Å-thick) of the growth process. The p-layer of conventional ITO/p-i-n photovoltaic cells has an island structure with a thickness in the range of 50 to 200Å.
A multi-junction model in which a-Si photovoltaic cells consist of an ITO/p-i-n junction (hetero-face junction) and an ITO/i-n junction (hetero junction) is proposed. The radius of the island structure in the p-type a-Si is calculated with this model. The result of the calculation is in approximate agreement with that of the observation by transmission electron microscopy. The dependence of the open-circuit voltage of Glass/ITO/p-i-n photovoltaic cells upon the p-layer thickness can be explained by the multi-junction model.
Study of Drift Type Photovoltaic Effect in Amorphous Silicon p-i-n Junction Structure
Authors: Yamaguchi Takeshi , Okamoto Hiroaki , Nonomura Shuichi , Hamakawa Yoshihiro
Published: March 2014

Taking account of continuously distributed gap states and a considerably small carrier mobility inherent to amorphous material, a unique photovoltaic behavior in an amorphous silicon has been examined in a p-i-n junction structure. Geminate and non-geminate recombination would play a significant role in the photo-carrier generation and photovoltaic carrier collection process, respectively. It has been shown that in the case of a properly designed a-Si:H p-i-n junction photovoltaic cell the carrier collection loss can be almost saved with the aid of high internal electric field in the i-layer despite of a very small hole diffusion length of about 500Å. While, owing to the geminate recombination, as high as 20% of absorbed photons are still thrown away without being converted to photocurrent.
A New Integrated Type Amorphous Si Solar Cell
Authors: Kuwano Yukinori , Tsuda Shinya , Ohnishi Michitoshi , Nishiwaki Hidenori , Shibuya Hisashi , Nakano Shoichi , Imai Terutoyo
Published: March 2014

The conversion efficiencies of amorphous silicon (a-Si) solar cells were found to decrease with an increase of the cell size. The cause of this effect was investigated, and a part of the cause was indicated by a distributed constant model. In order to enlarge the size of a solar cell with high efficiency, we have developed an integrated structure for the a-Si solar cell module. The best conversion efficiency of this module with a size of 10×10 cm2 was 3.4% in sunlight.
Parallel- and Radial-Current Stream-Line Type Metal-Contacts of Solar Cell
Authors: Yonei Kenji
Published: March 2014

Solar cells are basically composed of a p-n junction with a large surface area and a thin board structure to convert directly solar radiation into electrical energy with high efficiency and low material cost. The output of the converted electrical energy is performed by the metal-contact of the back-side and the window-side, and the transparent-conduction region. In this paper, the output-energy loss in the transparent-conduction region is clarified theoretically in the case of parallel- and radial-current stream-line type metal-contact structures. Also, to appraise the overall output-energy loss, the mean surface resistivity of these window-side metal-contacts is analysed.
A New Structure for High Efficiency and Humidity Resistant AlGaAs/GaAs Solar Cells
Authors: Mitsui Kotaro , Yoshida Susumu , Oda Takao , Yukimoto Yoshinori , Shirahata Kiyoshi
Published: March 2014

For p-AlGaAs/p-GaAs/n-GaAs heteroface solar cells, the results of humidity resistance test under the condition of 65°C and ≥90% relative humidity are described.
Humidity resistant cells with high efficiency over 20% have been attained by (1) covering the side walls of the p-AlGaAs layer as well as the top surface with CVD Si3N4 antireflective coating, (2) covering CVD Si3N4 with relatively thick CVD SiO2, and (3) forming p-contact on p-GaAs.
Introduction to Films of Computer Simulation of Elastic Waves in a Solid
Authors: Harumi Kasaburo , Saito Tetsuo , Fujimori Toshiaki
Published: March 2014

The outline of three films of a computer simulation of elastic waves is summarized. The computer simulation of the radiation of elastic waves from a normal transducer on a solid half space is treated in the first film, and the radiation of elastic waves from a y-cut transducer is shown in the second film. Reflections of a longitudinal or transverse wave by a crack of simple shape are clarified in the third film. Mechanisms of the radiation or refraction of elastic waves are disclosed by computer simulation.
Defects in Synthetic Quartz and the Q-Values of the -18.5° X-Cut Bar
Authors: Oura Nobunori , Kuramochi Naimu , Koshino Masayoshi , Katsumoto Toru
Published: March 2014

-18.5° X-cut bar crystal blanks, 25.0×1.50×1.25 mm in size, were cut from different synthetic mother quartz. Defects in the bars were observed by light scattering tomography and X-ray traverse topography, Q-values were measured in the second overtone mode of 200 kHz in the air gap type holder and the maximum Q of 5.4×106 was obtained. Infrared absorption of the mother quartz, observed defects and the measured Q-values were discussed.
Electrical Properties of Grain-Oriented Piezoelectric Ceramics in Layer-Structure Oxide Family
Authors: Takenaka Tadashi , Sakata Koichiro
Published: March 2014

Electrical properties of some ferroelectric layer-structure oxides related to bismuth titanate have been studied on grain-oriented ceramics. The specimens were prepared by the hot-forging method. The ceramics were highly anisotropic: the ratio of dielectric constants perpendicular and parallel to the forging axis was 3.9–12.3 at the Curie point.
Ferroelectric properties of a hot-forged La
x
Bi4-x
Ti3O12 (0≦x≦1) system were compared with ordinarily fired ones. The remanent polarization P
r perpendicular to the forging axis was much larger than P
r observed in the latter. The hot-forged ceramics of La0.75Bi3.25Ti3O12 are probably useful for piezoelectric materials.
Ultrasonic Mass-Screening System for Breast Examination
Authors: Takamizawa Kinya , Hashiguchi Mutsuo , Uchiumi Isao , Honda Hiroki , Iinuma Kazuhiro , Takehara Yasuaki , Matsukawa Masao , Hisada Yuichi
Published: March 2014

A new ultrasonic mass-screening system for the early detection of breast cancer without palpation is described. This system has been developed in order to detect a tumor larger than 5 mm in size. The entire region where breast cancer may develop can be scanned at one time by rotating the 5 MHz waterproof array transducer in a water bath. The real-time B-mode image with a wide viewing width of 190 mm can be obtained by electronic linear scanning. The screening time is less than 5 minutes per examinee. This trial system is confirmed to be effective for clinical mass-screening.
Critical Divergence of Ultrasonic Absorption in Binary Fluids
Authors: Harada Yoshifumi , Ishida Yoshio
Published: March 2014

Ultrasonic absorption measurements for a critical binary mixture of 3-methylpentane-nitroethane have been made over a wide reduced frequency range, 10-1<ω*106; ω*=ω/ωc, where ω is the frequency of sound and ωc is the relaxation frequency. Near the critical temperature T
c=26.50°C a critical divergence of sound absorption was observed. The experimental results were analyzed numerically within the framework of the existing mode coupling theory for sound propagation. In order to clarify the discrepancy between the theory and the experiment, a computer calculation was made on a set of critical relaxation curves and temperature dispersion relations. As a result, it is shown that the existing mode coupling theory breaks down over a wide range of frequency and temperature. The universal scaling function for this binary mixture has been derived empirically using the extended dynamical scaling approach.
Photoacoustic Effect in Laser Annealing
Authors: Hoh Koichiro
Published: March 2014

The acoustic wave generated in a silicon crystal during the laser annealing has been observed. The acoustic signal increases steeply with the incident laser energy beyond the melting threshold. This is explained by the increase of the optical absorption coefficient and the resultant increase of the temperature gradient in the sample accompanying the surface melting. The photoacoustic effect can be utilized for monitoring the melting state in laser annealing.
Ultrasonic Spectroscopy in Liquids by High-Resolution Bragg Reflection Technique
Authors: Takagi Kenshiro , Choi Pak-Kon , Negishi Katsuo
Published: March 2014

The HRB technique which is useful for measurement of ultrasonic properties is briefly reviewed. This technique observes the k-spectrum of sound by light scattering and optical beat detection of the scattered light, yielding velocity and absorption over a frequency range from 50 MHz to 1.5 GHz. Studies were made on ultrasonic relaxation phenomena in carbondisulfide and in a mixture system of furan and cyclohexane. Brief discussion is given on the mechanism of vibrational relaxation in these liquids.
Low Loss 1–2 GHz SAW Filters with Submicron Finger Period Electrodes
Authors: Asakawa Kiyoshi , Itoh Masaki , Gokan Hiroshi , Esho Sotaro , Nishikawa Katsuhiko
Published: March 2014

Low loss GHz SAW filters with submicron finger-period double electrodes have been developed. One was a 1 µm period 0.9 GHz filter with 5 dB insertion loss and the other a 0.5 µm period 1.9 GHz filter with 7 dB loss, both having three-transducer configurations on a 128° Y-X LiNbO3 substrate. These filters were realized by a new fabrication process, using direct wafer electron beam writing, two step mask transfer from electron resist PMMA to photoresist AZ-1350J and ion beam etching. The insertion loss was lowered mainly by optimizing ion beam etching conditions to decrease acoustic propagation losses due to electrode edge geometries, ion etched surface damages and electrode film absorption.
2.2 GHz SAW Filters Using ZnO/Al2O3 Structure
Authors: Mitsuyu Tsuneo , Ono Shusuke , Wasa Kiyotaka
Published: March 2014

This paper describes 2.2 GHz surface-acoustic-wave (SAW) filters fabricated on ZnO/Al2O3 structures. The single-crystal ZnO films on AL2O3 (sapphire) substrates have been grown by rf magnetron sputtering and are found to exhibit excellent SAW properties. Minimum line-width of electrodes used for the filter is 0.875 µm. High phase velocity of a higher order mode in the substrate structure and harmonic generation by split electrodes make it possible to use such wide electrodes even at 2.2 GHz. The filter has shown considerably low insertion loss of 12.5 dB at the center frequency.
First and Second Order Group Timing Tank Ceramic Filters for PCM Carrier Systems
Authors: Inoue Takeshi , Takahashi Sadayuki , Kawana Takayuki , Ishioka Masatsugu
Published: March 2014

Timing extraction use ceramic bandpass filters for 1st (1.544 Mbit/s) and 2nd (6.312 Mbit/s) order group PCM carrier systems were examined. Two trapped energy piezoelectric ceramic strip resonators operated with thickness shear vibration mode and three ceramic capacitors were used for each filter. Gaussian approximated effective parameter theory is applied in a circuit design. For both filters, temperature coefficients of the center frequencies are below 10 ppm/°C. The aging rates are 0.01%/decade. Both filter sizes are reduced to 1/5 that of the usual L
C filters.
Energy Trapping of Width-Shear Vibrations in Thin Piezoelectric Strips
Authors: Watanaba Hiroshi , Shimizu Hiroshi
Published: March 2014

This paper presents theoretical analyses and experiments of energy trapping of width-shear vibrations in thin piezoelectric strips. By the use of width-shear vibrations, miniaturization of trapped-energy resonators is achieved in the medium-frequency range below several megahertz. The width-shear-mode trapped-energy resonators have some advantages, such as: 1) Excitation electrodes are deposited only on the one side of the plate. 2) The ratio of capacitances of the resonator can widely be varied by the electrode spacing. 3) A specified higher-harmonic mode can easily be suppressed by special electrode arrangement related to stress distribution of the mode. In addition, trapped-energy single-mode filters using the width-shear modes are proposed, and small-sized filters of 455 kHz are constructed.