bluuebunny/crossref_metadata_2025 huggingface dataset:
A 100 W Static Induction Transistor Operating at 1 GHz
Authors: Kajiwara Yasuya , Aiga Masao , Higaki Yukio , Kato Mari , Yukimoto Yoshinori , Shirahata Kiyoshi
Published: March 2014

A 1 GHz 100 W in CW Static Induction Transistor (SIT) has been realized. At 1 GHz CW operation, a power gain of 4 dB and a drain efficiency of 55% with an output power of 100 W were obtained. The saturation output power at 1 dB gain compression point was 100 W. To realize above 1 GHz 100 W SIT, two important techniques were improved. One was the fine patterning technique. Very fine patterns with 1 µm width and total length of 19.8 cm were fabricated in a 100 W SIT. Another was the power combination technique. The power was shared equally with 12 transistor blocks by internal matching networks.
A New Transistor with Improved Safe Operating Area
Authors: Kondo Hisao , Yukimoto Yoshinori
Published: March 2014

Gate Associated Transistor (GAT) has been shown to have larger safe operating areas (SOAs) than conventional transistors in both forward and reverse base drive operations. Improvement in SOAs was achieved by the gate shielding effect, which suppressed both current crowding in base layer and avalanche multiplication in collector region.
High frequency GATs were fabricated with a maximum oscillating frequency F
max of 400 MHz, collector-emitter breakdown voltage B
V
CEO of 240 volts. The output power of 52 W, gain of 20.2 dB, and efficiency of 68% in B class amplifier at the operating frequency of 30 MHz were obtained.
(Invited) LSI Prospects of GaAs FET's
Authors: Zuleeg R.
Published: March 2014

An assessment is presented of the inherent properties of GaAs FET technology which qualify its application to large scale integration. Although the processing technology is not advanced to produce the described optimum logic gate configuration, it is demonstrated that 1 µm channel length FET's produce delay-power products of less than 100 femto-Joules, a prerequisite for LSI. Several exploratory designs will be discussed which have achieved gigabit data rate handling capability not accessible with Si device technology.
Power GaAs MESFETs with a Graded Recess Structure
Authors: Higashisaka Asamitsu , Furutsuka Takashi , Aono Yoichi , Takayama Yoichiro , Hasegawa Fumio
Published: March 2014

A new recess structure called a graded recess structure was developed to improve the performance of power GaAs MESFETs. The investigation on the light emission from the device confirmed that the anomalous electric field outside the gate region was eliminated by the graded recess structure. Due to the elimination of the anomalous field, the drain and the gate breakdown voltages were improved. The linear gain and the output power of the devices were resultantly improved by 1–2dB, and the output powers of 15 W (4 dB gain) and 4.3 W (3 dB gain) were obtained at 6 and 11 GHz band, respectively.
A New Type GaAlAs Monolithic Lensed LED
Authors: Abe Masayuki , Hasegawa Osamu , Komatsu Yasuaki , Tōyama Yoshikazu
Published: March 2014

A new type GaAlAs monolithic lens coupled LED has been proposed and developed to achieve the highly efficient performance for fiber-optical communications. A GaAlAs lens monolithically formed on the LED surface and the spherical-ended fiber furnish efficient coupling under the optimized design. In the lensed LED having the magnification β of 2, the efficiency was improved 4 times better than in a flat LED. The lens radius of 80 µm and thickness of 56 µm are chosen. The improvement factor β2 in efficiency was confirmed for β of from 1.6 to 2.2. For LED with an emitting diameter of 20 µm, operated at the forward current of 100 mA, powers of 0.7 and 1.2 mW were coupled into step index fibers with 0.16 N.A., 85 µm core, and 0.28 N.A., 100 µm core, respectively.
(Invited) Electron Image Projection
Authors: Daniel P. J. , Kramer R. P.
Published: March 2014

An assessment is given of the characteristics of electron image projection as a lithography system for integrated circuit production. The resolution and pattern registration capabilities are considered and factors affecting yield and economics discussed.
A Coupled-Waveguide TE/TM Mode Splitter
Authors: Mikami Osamu
Published: March 2014

A novel channel waveguided TE/TM mode splitter is presented. This splitter can spatially separate the TE and TM mode components and is compatible with single mode fiber systems. The operation principle is as follows. Two straight waveguides are formed closely parallel to each other on c-plate LiNbO3 by preferential Ti diffusion. An Al strip loaded on waveguide 2 induces a large change in the propagation constant for the TM mode, so that the TM mode component, fed into waveguide 1, cannot couple to waveguide 2 (“straight-through state”). By applying external voltages V
1 and V
2 to the two planar electrodes, formed on waveguide 1 with an Al2O3 buffer layer in-between, a complete power transfer from waveguide 1 to waveguide 2 takes place for the TE mode (“crossover state”). Less than -20 dB crosstalk was realized at 1.15 µm wavelength for V
1=20 V and V
2=-15 V. The insertion loss was 1.7 dB.
Metal-Semiconductor-Metal Photodetector for High-Speed Optoelectronic Circuits
Authors: Sugeta Takayuki , Urisu Tsuneo , Sakata Seizo , Mizushima Yoshihiko
Published: March 2014

A new metal-semiconductor-metal photodetector (MSM-PD), which is incorporated with coplanar striplines on high resistivity GaAs and has ultrahigh speed, is proposed and investigated experimentally as well as theoretically. A photocurrent gain over 50 has been observed at low frequency. In the high frequency region, the flat primary photocurrent response up to 1.5 GHz was obtained and the switching speed less than 100 ps was observed for GaAlAs laser pulses. Potentiality for detecting picosecond pulses is predicted. Photoresponse is almost flat in the wavelength region from 0.45 µm to 0.87 µm.
Applications of MSM-PDs to optoelectronic logic circuits, such as AND gate and INHIBITOR, are demonstrated at less than 200 ps switching speeds.
Characterization of InxGa1-xAs1-yPy Epitaxial Layers and Relation to Lattice Matching
Authors: Tamura Akiyoshi , Oka Koji , Inoue Masataka , Shirafuji Junji , Inuishi Yoshio
Published: March 2014

The minority carrier (electron) diffusion length in Zn-doped p-In0.80Ga0.20As0.44P0.56 epitaxial layers (p∼1018 cm-3) ranges from 1.7 to 0.76 µm, almost independent of the magnitude of the lattice mismatch, in the mismatch range ±0.2%. It is found that the minority carrier (electron) diffusion length was determined mainly by point-defect centers or by direct radiative recombination. Two electron traps which locate at 0.60 and 0.67 eV below the conduction band are observed by DLTS in undoped n-In0.77Ga0.23As0.35P0.65 layers (n=1.7×1015∼5.1×1016 cm-3). The density of the 0.67 eV trap is, remarkably dependent on the lattice mismatch, 2.4×1013 cm-3 at the matched condition and 9.7×1015 cm-3 at the mismatch of +0.21%.
Magnetooptical Properties of MnBi Films Prepared by lonized-Cluster Beam Deposition Technique
Authors: Takagi Toshinori , Matsubara Kakuei , Kondo Naoto , Fujii Kenichi , Takaoka Hiroshi
Published: March 2014

Ionized-Cluster Beam (ICB) deposition technique developed by the authors was successfully used to prepare a ferromagnetic MnBi for magnetooptical memory applications. The film deposited simultaneously Mn and Bi onto a glass substrate by the technique, followed by annealing at 300°C for 3 hr was entirely uniform over the large substrate area, and showed a high stability in the thermal writing over a number of cycles. The nucleation and crystal growing processes of the films formed by the method were studied, and it was found that the crystal growth of MnBi starts at the annealing temperature as low as 100°C, which is nearly 1/3 of the corresponding temperature in the conventional vacuum evaporation. These results are interpreted as due to the charged particles and their kinetic energies.
Ion Implanted Grating Type Si Solar Cells
Authors: Hwang Huey-liang , Tang Ru-shyah , Loferski Joseph J. , Yang Ying-Chuan
Published: March 2014

Silicon grating-type solar cells have been fabricated by ion-implantation techniques. The cells as-fabricated showed maximum V
oc of 0.54 V, and maximum I
sc of 34 mA/cm2 (without AR coating) under an AM1 illumination, and maximum FF of 0.68. The series resistance problems were examined, and metal gridding superimposed on the grating was found essential. The effects of impurity profiles and the annealing conditions have
been studied. For a fixed value of junction depth, the cell output peaked for doping levels around 1019 cm-3. For a fixed grating geometry, it was found within the limits of the implanted ion concentration, the deeper the junction the higher the cell efficiency, which is in contrast to the commonly shallow junction cells. It was also found that slow cooling from thermal annealing is essential in improving the ion-implanted solar cell efficiencies.
High Efficiency AlxGa1-xAs–GaAs Solar Cells with High Open-Circuit Voltage and High Fill Factor
Authors: Yoshida Susumu , Mitsui Kotaro , Oda Takao , Sogo Toshio , Shirahata Kiyoshi
Published: March 2014

Solar cells consisting of p–Al
x
Ga1-x
As/p-GaAs/n-GaAs have been fabricated by the liquid phase epitaxial growth of Zn-doped Al
x
Ga1-x
As on (111)B n-GaAs substrates.
High conversion efficiencies of about 21% at air mass 1.4, with a high open-circuit voltage (1.00–1.01 V) and a high fill factor (0.82–0.84), were reproducibly obtained together with the reduction in the dark current. This was realized by driving the p-n junction depth (width of the p-GaAs region) into about 3–5 µm deep below the Al
x
Ga1-x
As–GaAs interface. The p-n junction was controlled by varying the soaking time,during which a substrate was soaked isothermally in the saturated Al–Ga–As Zn doped melt, at fixed Zn content.
Reactive Sputter Etching System with Floating Grid
Authors: Shibayama Hikou , Ogawa Tetsuya , Kobayashi Koichi , Hisatsugu Tokushige
Published: March 2014

A reactive sputter etching (RSE) system with a floating grid (FG) is studied in an effort to eliminate damage to Si wafers during the etching process. In this system, an FG is used as a third electrode between the anode and cathode in an otherwise conventional diode-type RSE system. This causes the discharge current to increase because the FG, together with the cathode, acts as an electrode to generate the hollow cathode effect in glow discharge. As a result, the etch rates for various materials increase, and the self bias voltage at the cathode drops sharply as compared with that of a conventional system. Since the damage depends on the self-bias voltage, it is possible to etch specimens without damage. This paper presents the etching characteristics of the RSE system with the FG.
Experimental Integrated Microwave Circuits with Josephson Junctions
Authors: Wiik Tapio , Ronkainen Hannu , Stubb Tor
Published: March 2014

An experimental thin film circuit consisting of two Josephson tunnel junctions coupled together by a microstrip transmission line is described. One junction is operating as a signal source and the other as a dectector. Changes in the current-voltage characteristics of the detector junction indicate strong coupling between the junctions at microwave frequencies. An approximate calculation for estimating the coupling efficiency is presented.
Fabrication of High Quality NbN/Pb Josephson Junction
Authors: Shinoki Fujitoshi , Takada Susumu , Kosaka Shin , Hayakawa Hisao
Published: March 2014

A fabrication technology of NbN/Pb Josephson tunnel junctions has been developed by using a new microfabrication technique. The Josephson characteristics of NbN/Pb tunnel junctions formed on rf reactive sputtered NbN films are reported. The junctions are found to have large gaps (Δ
NbN+Δ
Pb=3.8 mV), low leakage, and to be quite stable with respect to thermal cyclings and storage at room temperature.
Fabrication of Josephson Weak Links Using Electron Beam Lithography and Ion-Etching, and Proposal of a New Single Flux Quantum Logic
Authors: Tamura Hirotaka , Okabe Yoichi , Sugano Takuo
Published: March 2014

A new single flux quantum device is proposed, and, in conjunction with it, fabrication process of Josephson weak links using electron beam lithography and ion-etching is reported. Two types of niobium weak links, microbridges and thick-thin-thick type bridges, have been fabricated. They showed dc supercurrent, but microwave-induced steps were observed for thick-thin-thick type bridge only. The proposed logic device is constructed with a magnetically coupled rf-SQUID cells. These cells behave in the similar manner as “Domino-toppling”, and basic logic operations, AND, OR and NOT, are demonstrated by numerical calculations. Switching delay of about 10ps is expected to be practical.
Ion Implanted Silicon Molecular Beam Epitaxy (I2 Si MBE)
Authors: Ota Yusuke
Published: March 2014

Arsenic-doped n-type silicon epitaxial films have been grown by molecular beam epitaxial technique, utilizing low energy As+ ion implantation. A convenient acronym for this combination is I2 Si MBE for Ion Implanted SiMolecular Beam Epitaxy. Arsenic ions (As+) accelerated to energies between 400 and 800 eV have shown a high sticking coefficient on a heated silicon surface. Precise control of doping density and profile has been achieved. Growth conditions have been defined at which epitaxial films with bulk characteristics can be grown.
(Invited) Surface-Acoustic-Wave Devices for Spread-Spectrum Communication
Authors: Cafarella John H.
Published: March 2014

The technique of spreading the transmitted bandwidth of a message far in excess of the information bandwidth has long been used in military communication systems for interference rejection. Spread-spectrum systems have also become of increasing interest for domestic applications such as police communication. Additional benefits of spread-spectrum communication include the prevention of eavesdropping and unauthorized use of the channel. There are a variety of surface-acoustic-wave (SAW) devices which are of current interest to the spread-spectrum community because of their powerful ability to demodulate received spread-spectrum signals. One of these devices is the SAW convolver. The operation of SAW convolvers and convolver-based communication systems will be described.
The advantages of spread-spectrum techniques, in terms of their interference
rejection properties will be reviewed. The time-frequency-plane description of large-time-bandwidth-product wave forms will be used to indicate typical spread-spectrum signals such as pseudonoise and frequency hopping.
Correlation reception is convenient when the timing of a message is relatively well known. In circumstances where timing is not so well known, the technique of matched filtering is preferred. Until recently, available technology for matched filtering has dictated the use of a fixed spreading code in spread-spectrum systems. The development of the SAW convolver has allowed the use of continuously changing wave forms while still providing matched-filter operation. The operation of an acoustoelectric, separated-media convolver will be described. Other convolver structures of current interest will will also be reviewed.
Surface Acoustic Solitons
Authors: Ewen J. F. , Gunshor R. L. , Weston V. H.
Published: March 2014

The possibility of solitary wave propagation in SAW materials is examined. A simple, one-dimensional model is developed to describe the system which predicts the existence of solitary waves. A number of SAW configurations are examined using this model.
(Invited) Non-Thermal Carrier Generation in MOS Structures
Authors: Kohyama Susumu , Furuyama Tohru , Mimurat Shouichi , Iizuka Hisakazu
Published: March 2014

Influence of generated carriers originated by hot electrons and radiations is described in MOS structures. A holding time degradation in a dynamic RAM is first presented with the two-step impact-ionization model, which is verified by a series of experiments. The impact ionization rate in the high electric field near the drain is also calculated by a two dimensional analysis, which leads to an accurate substrate current estimation. Effects of hot electron injection into the gate oxide, and of trapping are then studied utilizing a stacked gate MOS structure. From those results, design constraints in small geometry MOS LSI's are discussed.
Design Limitations due to Substrate Currents and Secondary Impact lonization Electrons in NMOS LSI's
Authors: Matsunaga Jun-ichi , Kohyama Susumu , Konaka Masami , Iizuka Hisakazu
Published: March 2014

A quantitative analysis of the substrate current and its secondary effects in NMOS LSI's are described. The substrate current is accurately calculated by a two-dimensional numerical analysis for short channel transistors down to 1 µm channel length. Minority carrier injection in substrate, which results from a secondary impact ionization, is also studied. The minority carrier current in the substrate is measured using a CCD test device, and is found to be nearly proportional to the substrate current. A physical model
for these phenomena is also presented. Minority carrier injection efficiency is then given by an empirical equation as a function of effective channel length. Based on the models and experimental results, limiting voltages for MOS LSI's are estimated in terms of punch-through, parasitic bipolar transistor breakdown, excess electrons and hot electron trapping.
Near Ideal Si–SiO2 Interfaces
Authors: Kasprzak L. A. , Gaind A. K.
Published: March 2014

The Si–SiO2 interface plays a key role in the IGFET (insulated gate field effect transistors). Of principle concern are interface charge (Q
ic) and fast states (N
fs). The properties of the interface Q
ic and N
fs can be optimized by eliminating the transition region and creating an abrupt interface. Our work in the CO2, SiH4, H2 system with and without HCl at 1000°C has demonstrated that CVD SiO2 can indeed equal thermal SiO2 on (100) surfaces. Further by using HCl we have achieved Q
ic...5×1010 and N
fs...1010 on (111) surfaces, which is clearly superior to thermal SiO2 on (111) surfaces. We attribute the excellent results achieved, at least in part, to the abrupt interface between the CVD SiO2 and Si, since deposition rates of 10 to 20 nm per minute were used to deposit 30 to 50 nm of SiO2. In general N
fs was found to be independent of Q
ic.
Deposition and Properties of Polycrystalline Si for Solar Cells
Authors: Mitani Kiyoshi , Nishino Shigehiro , Matsunami Hiroyuki , Tanaka Tetsuro
Published: March 2014

A tin coated graphite substrate was used for growing polycrystalline Si layers by CVD in the SiCl4–H2 system. A mean grain size of poly-Si layers on the tin coated substrate was 50–100 µm, compared with several microns on an uncoated substrate. Moreover the tin intermediate layer seems to play an important role to make a flat surface. The crystalline size could be further enlarged to 100–500 µm by introduction of melting process before normal CVD. A Schottky barrier solar cell using those poly-Si layers showed the open-circuit voltage of 0.25 V, the shortcircuit current density of 12.8 mA/cm2, fill factor of 59% and conversion efficiency of 2.0% under the solar intensity of 92.8 mW/cm2.
Anisotropy of Photovoltaic Properties of Au-CdSnP2 Diodes
Authors: Matsumoto Takashi , Ishida Tetsuro
Published: March 2014

Photovoltage spectra have been measured on surface-barrier diodes prepared on CdSnP2 crystals at room temperature using polarized light. Au metal is vacuum-deposited on the {112} shiny surfaces of CdSnP2. Anisotropy in photovoltage spectrum is observed near the fundamental absorption edge. A strong edge and a weak edge are observed respectively at the A and B band gap in the E//c spectrum. On the other hand, a weak edge and a strong edge are observed respectively at the A and B band gap in the E⊥c spectrum. These structures are discussed on the basis of the band structure and selection rules for the optical transitions in the CdSnP2 crystal. Another peak in photoresponse is observed at an energy 0.03 eV lower than the A energy gap, and it is correlated with photoluminescence spectra.
Effects of the Basal Plane of CdS Single Crystal on the Growth of Cu2S and the Electric Properties of the Cu2S–CdS Solar Cells
Authors: Kobayashi Akihiko
Published: March 2014

Different growth behaviour of the Cu
x
S layer was obtained experimentally when the Cu
x
S layer was grown chemically on the basal plane of the CdS. The growth process of the layer is discussed by assuming the different diffusion velocities of Cd element in the Cu
x
S and Cu2S. The electric properties of the non-heat treated single crystal Cu2S–CdS heterojunction diode are also discussec with respect to the variation of the constituent elements in the transition region of the heterojunction diode.
Screen-Printable Electrode Material for CdS and Its Application to Solar Cell
Authors: Nakano Akihiko , Matsumoto Hitoshi , Nakayama Nobuo , Ikegami Seiji
Published: March 2014

A screen-printable electrode material which makes an ohmic contact to an n-type CdS film was developed. The material consists of 20 wt% of indium fine powder and 80 wt% of a commercially available electroconductive silver paint. The electrodes formed on the CdS film under the optimum condition showed linear current-voltage characteristics, and gave a low contact resistance of 5.0×10-2 Ωcm2.
The material was applied to fabrication of a CdS/CdTe solar cell as electrodes of CdS. The solar cell showed nearly the same intrinsic conversion efficiency, open circuit voltage and short circuit current as those with indium metal electrodes formed by the vacuum evaporation method.
Photovoltaic Properties of Cuprous Selenide-Semiconductor Junctions
Authors: Ohsawa Osamu , Iwase Mitsuo , Okimura Hiroshi
Published: March 2014

Cu2-x
Se thin films were deposited on three kinds of n-type semiconductor substrates of Si, GaAs and InP by vacuum evaporation. The junctions exist in substrate materials and their electrical and photovoltaic properties were strongly influenced by substrate semiconductors. The highest solar conversion efficiencies obtained were 8.3% in Cu2-x
Se–n·Si cells, 6.0% in –n·GaAs and 5.5% in –n·InP cells without antireflection coating at room temperature.
Photoelectric Effects in Organic Diodes
Authors: Iriyama Keiji , Shiraki Masaru , Tsuda Keishiro , Okada Akira , Sugi Michio , Iizima Shigeru , Kudo Kazuhiro , Shiokawa Shoko , Moriizumi Toyosaka , Yasuda Tsutomu
Published: March 2014

Photovoltaic behavior of the merocyanine dye family with a rhodanine ring has been systematically studied by employing eight different derivatives in the diode structure Al/evaporated dye/Ag. Each dye film behaves like a p-type semiconductor with a rectifying barrier at Al interface and an Ohmic contact at Ag electrode. The open circuit photovoltage as high as V
oc≃1.5 V was observed for one of the derivatives, while the fill factor remained f.f.≃0.25 in all cases. The chemical stability of the dye molecules during and after evaporation is also discussed on the basis of the results obtained by the thin-layer chromatography.
(GaAl)As/GaAs Solar Cells–Dopant Study of Zn and Be
Authors: Masu Kazuya , Konagai Makoto , Takahashi Kiyoshi
Published: March 2014

Electrical properties and the acceptor energy level in Zn or Be doped p-Ga1-x
Al
x
As (0<x<0.85) prepared by liquid phase epitaxy have been investigated. The acceptor energy levels in p-Ga0.25Al0.75As were found to be 65 meV for Zn and 47 meV for Be, respectively. The resistivity of p-(GaAl)As layer would be reduced by using Be as p-type dopant, so in the application for the (GaAl)As/GaAs concentrator solar cells Be was found to be more suitable dopant to reduce the surface sheet resistivity as compared with Zn. The increase of the acceptor energy level with increasing x in Ga1-x
Al
x
As has been explained by the modified hydrogenic model proposed by Baldereschi and Lipari. Furthermore, Zn doped or Be doped p-(GaAl)As/p-GaAs/n-GaAs solar cells had the sufficiently high conversion efficiency of 20.3% and 20.7% (AM1), respectively.
A Computer Analysis of CdS–InP Heteroface Solar Cells
Authors: Yoshikawa Akihiko , Yamaga Shigeki , Kasai Haruo , Nishimaki Masao
Published: March 2014

Theoretical analysis of n-CdS/n-InP/p-InP heteroface solar cells was performed. First, the internal spectral responses were calculated taking the n-CdS and n-InP layer thickness as parameters, where the effects of collection from the CdS layer, recombination at the CdS surface, and recombination at the CdS–InP interface were included. Then the internal photocurrent and the corresponding conversion efficiency for AM0 were computed. In the calculation of the conversion efficiency, the effects of two current transport mechanisms, the diffusion current and the recombination current, were considered. It is shown that if the thickness of the CdS layer is less than 0.15 µm, efficiencies more than 20% can be achieved. The highest efficiency for a device with 0.05 µm CdS layer is 21.7% under AM0 condition.
InP (MIS) Schottky Barrier Solar Cells
Authors: Kamimura Kiichi , Suzuki Toshihide , Kunioka Akio
Published: March 2014

InP Schottky barrier solar cells are fabricated and the device parameters are measured under solar illumination. The barrier height of n-InP Schottky contact increases by surface oxidation in wet O2 atmosphere. The oxidation time can be decreased by surface treatment with bromine water. No surface oxidation is carried out for p-type sample. The maximum open circuit photovoltage and the maximum energy conversion efficiency are 0.59 V and 6.9% for n-type sample and are 0.69 V and 5.6% for p-type sample.
New Wavelength-Demultiplexing InGaAsP/InP Photodiodes
Authors: Tobe Miharu , Sakai Shiro , Umeno Masayoshi , Amemiya Yoshifumi
Published: March 2014

The new wavelength-demultiplexing photodiodes which have the ability to demultiplex the incident light into two and three spectral regions were proposed and fabricated. The first type of the diode covers λ<0.95 µm and 0.95<λ<1.41 µm spectral regions. The second type of the diode covers 0.95<λ<1.28 µm and 1.28<λ<1.49 µm spectral regions. The anodic oxide was formed to restrict the electrode area as well as to prevent the reflection at the surface. The fabricated diode exhibited the quantum efficiencies of 85% and 63% and the crosstalks of -35.5 dB and -27.5 dB at λ=0.98 µm and 1.30 µm, respectively. The third type of the diode divides the spectral region into three parts; λ<0.95 µm, 0.95<λ<1.28 µm and 1.28<λ<1.49 µm. These diodes are useful for wavelength-multiplexed optical fiber communication system.
Impurity Gettering of Diffused Solar Cells Fabricated from Metallurgical-Grade Silicon
Authors: Saitoh Tadashi , Warabisako Terunori , Kuroda Ekyo , Itoh Haruo , Matsubara Sunao , Tokuyama Takashi
Published: March 2014

Damage gettering of undesirable impurities is attempted for crystalline wafers grown from commercial and refined metallurgical-grade silicon. The feasibility of impurity gettering is investigated by fabricating diffused solar cells and evaluating the photovoltaic characteristics.
In an O2 annealing, the fill factor of solar cells decreases to 0.25 due to junction leakage, while the factor is drastically improved by annealing in N2. A maximum conversion efficiency is attained to be 9.1% for single crystals grown from refined metallurgical-grade source.
Dark current-voltage characteristics are investigated by preparing small-sized diodes into gettered wafers. It is found that damage gettering affects the remarkable reduction of junction leakage and also enhances minority carrier lifetimes in the bulk crystals.
Electron Transport in Hydrogenated Amorphous Silicon Prepared by rf Sputtering
Authors: Kim Gi Il , Panyakeow Somsak , Shirafuji Junji , Inuishi Yoshio
Published: March 2014

Electrical and photoelectric properties of rf sputtered a-Si prepared under various deposition conditions have been studied. The a-Si films were deposited onto NESA coated glass substrates which serve as optical window for photoelectric measurements. The temperature dependence of the photoconductivity is tentatively understood on the model which includes two kinds of traps located near the conduction and valence bands. The photoconductivity and photovoltage are observed in the spectral region which is determined by the optical gap of a-Si and SnO2. It is confirmed experimentally that high photoconductivity is correlated closely to large photovoltage.
Characterization of Hydrogenated Amorphous Silicon: Some Behaviors of Hydrogen and Impurities Studied by Film Characterization Techniques
Authors: Imura Takeshi , Kubota Kazuyoshi , Ushita Katsumi , Hiraki Akio
Published: March 2014

Rutherford backscattering spectrometry and infrared absorption measurement were applied to determine composition in hydrogenated amorphous silicon fabricated either by glow discharge in SiH4 plus H2 or by reactive sputtering in Ar containing H2 in a tetrode or diode sputtering apparatus. The atomic density of Si, the content and depth distribution of H, and the amount of impurities such as Ar were studied for the films deposited under several conditions of substrate temperature and gas pressure and constitution. Some difference was clarified between glowdischarge and sputter deposited films.
Temperature Variation of Energy Gap Values in CuGa(Se1-xSx)2
Authors: Goodchild Gerald , Woolley John C. , Gonzales Jesus
Published: March 2014

Single crystal samples of CuGa(Se1-x
S
x
)2 alloys have been grown by an iodine transport method and measurements made of the reflectance spectrum of these samples in the temperature range 4–300 K. For each sample the values of energy gap E
A and E
B corresponding to the two higher valence bands A and B have been determined but the third gap could not be observed. The variation of E
A and E
B with temperature has been fitted to the equations proposed by Manoogian and Leclerc, i.e. E-E
0=U
T
s+Vθ(cothθ/2T-1). The variation of the parameters V and θ as a function of composition are discussed. For the case of CuGaS2, E
A-E
B gives the value crystal field splitting Δ
cf and the variation of this parameter with temperature is determined. It is shown that the variation in Δ
cf can be explained in terms of a variation with temperature in the contribution of the upper d orbitals to the valence band, the results being in fair agreement with the values proposed by Yamamoto et al.
Evaluation of ZnGeP2 Crystal for Temperature Dependent Phase-matched Nonlinear Interactions
Authors: Bhar Gopal C. , Ghosh G. C.
Published: March 2014

The chalcopyrite ZnGeP2 crystal possesses a high nonlinear figure of merit and reasonable value of temperature coefficient of birefringence. This makes it an interesting candidate to consider temperature dependent phase-matching characteristics for different nonlinear optical devices. For this purpose the refractive indices at different temperatures are evaluated by analyses of different methods. The peculiar features of temperature tuning (and angle tuning as well) in optical parameteric oscillator for different pumps have been worked out. It is also found that the crystal offers good temperature stability in difference-frequency generation and also in up-conversion. Finally, the importance of temperature tunability of nonlinear devices using other chalcopyrite crystals is pointed out.
An Evaluation of Some Physical Characteristics of CuInSe2 Thin Films Produced by R.F. Sputtering
Authors: Samaan A. N. Y. , Abdul-Hussein N. Abdul-Karim , Tomlinson R. D. , Hill A. E. , Armour D. G.
Published: March 2014

Rf sputtering has been used to produce thin films from pressed and loose powder CuInSe2 targets. A theoretical and experimental assessment of stoichiometry has been made using the Rutherford Back Scattering (R.B.S.) technique. Sputtering parameters and substrate temperatures have been varied and changes in film structure and electrical resistivity have been observed. Some preliminary results from a post deposition annealing program are presented.
Crystal Growth of CdCr2Se4 from High Temperature Solution
Authors: Okuda Takashi , Tsushima Tachiro , Masuda Takeo
Published: March 2014

Two methods of the crystal growth of CdCr2Se4 from high temperature CdCl2 solution were investigated. A conventional slow cooling method resulted in well-formed octahedral crystals with high reproducibility. The growth conditions were determined in detail. Another variation of a solution growth called the “travelling heater method” was adopted and a large single crystal of 8 mm diameter and 6 mm long was obtained. Several physical properties of each crystal grown by slow cooling method and travelling heater method were measured.
Unit Cell Step Structure on Vapour Grown CdCr2Se4 Single Crystals
Authors: Nakada I.
Published: March 2014

In order to study the mechanism of the crystal growth of CdCr2Se4 by the chemical vapour deposition, the surface micro-structure was examined with an interference contrast microscope. On the well-developed {111} face of the spinel we can find often regularly arranged monomolecular step structure which is intimately related with the crystal growth process.
The mean step height was found to be 6.5±0.5 Å which is equal to one third of the unit cell dimension in <111> direction. All the steps are generated either from a single spiral dislocation or from one point at the edge of the crystal. The steps are arranged with a regular separation of several micrometers. The bunching of the steps would have been prevented by the Schwoebel effect.
Vibrational Spectra and Effective Charges in Some Spinels
Authors: Wakamura Kunio , Ogawa Tsutomu , Arai Toshihiro
Published: March 2014

The infrared reflectivity spectra have been observed for sintered MCr2S4(M=Zn, Cd, Hg) near normal incidence in the range from 30 to 900cm-1. The effective charges of Cr and S ions are determined from the frequencies of transverse and longitudinal modes within small error. The Szigetieffective charges e
s
* per effective valency Z
eff for anions show the correlation with the low frequency electronic dielectric constant ε
∞ which has been established for selenide and oxide spinels and expressed as ε
∞-1=2.0/((e
s
*/Z
eff
e)+(e
s
*/Z
eff
e)2). By using this empirical relationship, the magnitude of effective charge of cation M is determined within the error in the charge of Cr ion. By the comparison among the obtained effective charges, dielectric constants ε
∞ and the lattice parameters, the increase of ionicity with the decrease of anion radius and a weak influence of chromium ion in comparison with that of cation M to the dielectric constant are shown. From these results, the similarity and the difference of dielectric properties between binary and ternary compounds are discussed.
Optical and Electrical Properties of Inverse Spinel Compound MgIn2S4
Authors: Wakaki Moriaki , Shintani Osamu , Ogawa Tsutomu , Arai Toshihiro
Published: March 2014

A single crystal of MgIn2S4 was grown by Bridgman method. The crystal structure of the crystal was measured by powdered X-ray diffractometer. By comparison of integrated diffraction intensity between experimental and calculated, the partially inverse structure was best fit to the experimental. The fundamental absorption edge is positioned at 2.14 eV. By using interference fringes of thin sample and prism method, accurate dispersion curve was obtained over the wavelength range 2.5–16µ. Five vibrational modes were observed in the lattice vibration spectrum. High electrical resistivity and n type conduction was obtained at room temperature.
Galvanomagnetic Properties of n-Type HgCr2Se4
Authors: Selmi A. , Gibart P. , Goldstein L. , Tomas A.
Published: March 2014

HgCr2Se4 crystals have been grown from the vapor. Se annealing gives p-type samples whereas Hg annealing gives n-type materials. The low temperature mobility of n-type HgCr2Se4 is about 2000 cm2/V·s. A jump of the resistivity appears around T
c. Under high applied field this jump completely disappears (Δρ/ρ=-0.99 at T
c under 150 kOe).
A defect model is proposed in which Se vacancies act as doubly charged donors and Hg as an acceptor. The carrier density can be controlled by heat treatment. A band scheme consistent with the available data is proposed.
Electrical Properties of the N-type Ferromagnetic Semiconductor HgCr1.9In0.1Se4/Ag Schottky-Barrier Diode
Authors: Koguchi N. , Masumoto K.
Published: March 2014

Measurements of the voltage-capacitance and voltage-current characteristics were performed on n-type ferromagnetic semiconductor HgCr1.9In0.1Se4/Ag Schottky-barrier diodes from 90 to 296 K in magnetic fields up to 1.19×106 A/m. The barrier-height of these diodes increases as the temperature is raised and decreases with the increase of the magnetic field in a manner similar to the optical absorption edge of the HgCr1.9In0.1Se4 single crystal. Temperature and magnetic field variations of both the barrier-height of these diodes and the optical absorption edge of the HgCr1.9In0.1Se4 single crystal can be explained consistently in terms of those of the electron affinity for HgCr1.9In0.1Se4 which decreases with the rise in temperature and increases with increasing magnetic field.
Electrical Properties of ZnCr2Se4
Authors: Watanabe Tsuneo , Endo Saburo , Kasai Akinari
Published: March 2014

The experiments of the electrical resistivity and magnetoresistance effect were performed on undoped p-type ZnCr2Se4 single crystals and Cu-substituted ZnCr2Se4 single crystals between room temperature and below T
N. Hall effect was also measured with Cu-substituted ZnCr2Se4 between 300 K and 4K. Remarkable variations were observed at ∼114 K and ∼22 K in the temperature dependence of electrical resistivity of any undoped samples. Negative magnetoresistance was also observed below ∼110 K and it increases with a peak in the vicinity of T
N. Anisotropy of the resistivity with respect to the crystallographic axes was recognized though it was small. High sensitive measurement of differential thermal analysis was carried out and anomalies of its signal were observed at ∼110 K, ∼64 K, ∼36 K and ∼22 K.
These results seem to indicate the interdependence between magnetic and electrical properties which is the characteristic of ZnCr2Se4.
LPE Growth and Luminescence of InGaAsP Lattice-Matched to (1, 0, 0) GaAs Substrates
Authors: Mukai Seiji , Shimada Jun'ichi
Published: March 2014

An LPE growth method is described for the growth of InGaAsP on (1, 0, 0) GaAs over a wide range of band-gap energy. Melt compositions and distribution coefficients of elements for lattice-matched growth of various layers are given. Observed band-gap energies and lattice constants of the layers are compared with formerly reported calculations. Photoluminescence spectral shape and spectral-peak energies are discussed in comparison with InGaAsP grown on InP. Doping of Zn and Te for p-type and n-type InGaAsP is also reported.
Preparation and Some Properties of CuInSe2 on ZnSe Heterojunction Grown by LPE
Authors: Takenoshita Hiroshi , Nakau Tanehiro , Nakao Itiro
Published: March 2014

CuInSe2 has been grown on ZnSe by LPE from the Bi solution. The value of lattice mismatch is 2.06%. The reflection electron diffraction pattern showed an epitaxial growth. Optimum growth condition was the following: maximum temperature of 600°C, cooling rate of 0.5°C/min, thickness of the over-growth layer of 6 µm and thickness of mixed crystal layer of 4.5 µm. The flatness of overgrowth surface was dependent on the substrate orientation and the quality was in order of (111)Se, (100), (111)zn and (110). Hall measurements on over-growth layer were carried out after the heat-treatment in Se and Zn atmosphere for 10 minutes at 600°C. The p·CuInSe2–n·ZnSe and n·CuInSe2–n·ZnSe heterodiodes were measured for their I–V, C–V characteristics and photoresponse. Especially, the n-n heterodiode showed a high photosensitivity.
Influence of Monovalent Ions on the Crystal Habit of Oxides and Chalcogenides
Authors: Heikens H. H. , Bruggen C. F. Van , Haas C.
Published: March 2014

Photoelectron spectra of α-MnS containing a trace of I- ions show that I- preferentially occupies sites at the (111) faces of these crystals.
It is expected that (100) surfaces of ionic crystals with the rocksalt structure are stable because these surfaces contain both cations and anions and have no surface charge. The (111) planes are expected to be unstable because they have an uncompensated surface charge. However the binding of a monolayer of monovalent ions exactly compensates the surface charge of a (111) plane of crystals of divalent ions. The monovalent ions stabilize the (111) faces, and this explains why oxides and chalcogenides with the rocksalt structure (usually grown in the presence of monovalent ions F-, Cl-, Br-, I-, OH-) crystallize in forms bounded by (111) planes, (octahedra). This effect can not occur for crystals with monovalent ions, and indeed the alkalihalides crystallize as cubes bounded by (100) faces.
Thermodynamic Considerations of Vapor Epitaxial Growth of CuInS2/GaP Heterojunctions
Authors: Hwang Huey-Liang , Tseng Bea-Hung , Sun Cherng-Yuan
Published: March 2014

Thermodynamic considerations were done to interpret the vapor growth mechanisms of CuInS2 layers on GaP substrates. The transport rate (Q
cuIns2
) and GaP etchiog cooceotsatioo were computed. The transport rate of CuInS2 at fixed reaction temperatures peaks at a certain iodine concentration. At fixed source temperature and iodine concentration, Q
cuIns2
increases with the temperature difference between the source and the substrate (Δ
T). Computational results of varying T
source, T
substrate, and Δ
T are included in this paper. The thermodynamic calculations provide accounts for the substrate etching. Furthermore, the transport rate is computed when nonstoichiometric materials are used as the source.
MBE Growth of CuInSe2 on CdS: Initial Stages
Authors: Clark A. H. , Unertl W. N.
Published: March 2014

Realization of the potentially high solar conversion efficiencies of CuInSe2/CdS heterojunctions has been hindered by a lack of knowledge and control of stoichiometry as well as cadmium diffusion in the CuInSe2 layer. In an attempt to understand these effects, we have used in situ Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) to study the early growth stages of CuInSe2 onto (0001B) CdS (T
sub=300°C) using molecular beam epitaxy (MBE). We find that 25Å thick CuInSe2 layers show bulk-like AES and EELS spectra, although several atomic percent cadmium is always present on the surface. The energy loss peaks (12.0±0.5 eV and 21.5±0.5 eV) have widths of about 5–6 eV compared to about 3 eV for CdS loss peaks (instrument limited). In order to produce layers with no detectable cadmium at the surface, the CuInSe2 must be several hundred Ångstroms thick. The metallurgical junction formed at T
sub=300°C is no wider than 10–20 Å, while the junction formed at T
sub=400°C is about 40–50 Å wide.
Solar Cells Made by Chalcopyrite Materials
Authors: Romeo N.
Published: March 2014

After a discussion of the material characteristics, which are necessary for high efficiency solar cells, some chalcopyrite materials are indicated as promising photovoltaic absorbers. Among these, CuInSe2, CuInSe1.66 Te0.34 and CuGaSe0.65 Te1.35 from the I-II-VI group and CdSiAs2 from the II-IV-V group seem to have a greater probability of success owing to their good lattice matching with CdS or ZnCdS. A brief review of the results obtained to date on single crystals and thin film solar cells is given, and this is followed by a description of a new technique, called Quasi-Rheotaxy, which allows one to obtain large grain thin films on amorphous low cost substrates. Quasi-Rheotaxy, which we used to grow ∼10 µm grain thin films of the above mentioned I-III-VI chalcopyrite materials could substancially contribute to achieving low cost high efficiency thin film solar cells.
Crystal Structure of Chalcopyrite AgInSe2
Authors: Benoit P. , Charpin P. , Lesueur R. , Djega-Mariadassou C.
Published: March 2014

The accurate determination of unit cell parameters and x
se position parameter is reported for the chalcopyrite AgInSe2. The structure refinement has been performed with 175 independent reflexions and their Friedel's pair measured on a single crystal with an automatic diffractometer. The unit cell parameters were found equal to a=6.1038 (15) Å, c=11.7118 (47)Å and Se position x to 0.25845 (16).
High Speed MoSi2-Gate CMOS/SOS Devices
Authors: Mizutani Yoshihisa , Maeguchi Kenji , Mochizuki Tohru , Kimura Minoru , Isobe Mitsuo , Uchida Yukimasa , Tango Hiroyuki
Published: March 2014

Characterization and optimization of CMOS/SOS devices with the effective channel length of 1.5 µm utilizing MoSi2-gate technology are investigated from the viewpoint of practical realization of CMOS/SOS VLSI's. Double ion implantation into the channel region was found to be effective for suppressing leakage currents in shorter channel CMOS/SOS devices.
Floating substrate effect due to charge pumping was also studied. Using the MoSi2-gate CMOS/SOS technology, feasibility for a 4K (4K×1)-bit static RAM was verified.
Custom LSI Process with a Micron Geometry, Partially Using Electron Beam Direct Writing
Authors: Endo Nobuhiro , Kurogi Yukinori , Suzuki Katumi , Sugimoto Masunori , Morimoto Mitsutaka , Iida Yasuo , Mori Katsumi
Published: March 2014

A custom LSI with a micron geometry has been developed using a 10 to 1 direct stepper and an electron beam direct writing. The electron beam lithography was used for only data writing, which was achieved by contact-hole opening, just before final metallization, to shorten the ROM production turn around time. Considering alignment and process compatibility between photolithographic step and electron beam lithographic step, all matching symbols for alignment are simultaneously delineated by the stepper and replicated by etching the substrate silicon. The obtained relative overlay accuracy for the electron beam exposure over the stepper image was less than ±0.35 µm. This process technology was successfully applied to the fabrication of a 512 kbit MOS ROM. The device operation was confirmed by displaying Chinese ideographs on the CRT.
N-Channel MNOS EAROM for TV Electronic Tuning System
Authors: Saito Shozo , Hashimoto Kazuhiko , Uchida Yukimasa , Endo Norio
Published: March 2014

A new n-channel MNOS technology for EAROM applications has been developed by introducing a threshold voltage control technique. The technology is principally based on a low energy implantation of boron ions for obtaining a positive center voltage in the threshold window, which results in better retentivity.
By incorporating this MNOS technology and n-well CMOS technology on an isolated epitaxial layer, an n-channel MNOS EAROM is fabricated for TV electronic tuning system. The EAROM utilizes the two MNOS transistors per cell configuration. The device showed a long data retention time over 10 years at 80 °C after 105 erasing/writing cycles, therefore the technology appears to be quite promising for EAROM applications.
Soft Error Improvement in MOS RAM's by the Use of Epitaxial Substrate
Authors: Satoh Shin-ichi , Denda Masahiko , Takano Satoshi , Fukumoto Takaaki , Tsubouchi Natsuro
Published: March 2014

The soft error improvement is discussed for 64 K-bit dynamic MOS RAM with epitaxial substrate, compared with the normal substrates with uniform resistivity. The total charge collected along α particle track is calculated with simplified model. The collection efficiencies which are obtained by comparing the total collected charges for various substrates are well related to the measured soft error rates. The results show that the use of epitaxial substrate for 64 K-bit dynamic MOS RAM is very effective to reduce soft errors due to α particles from radio-active elements.
High Speed Bipolar ICs Using Super Self-Aligned Process Technology
Authors: Sakai Tetsushi , Kobayashi Yoshiji , Yamauchi Hironori , Sato Masaaki , Makino Takahiro
Published: March 2014

We have developed a new bipolar process technology, called SST. The emitter region, base p region, base p+ region, base p+ polysilicon electrode and emitter contact window of NPN transistor are formed by one mask photolithography process. The transistor active regions are all self-aligned. Therefore, small-size transistors can be realized and high performance is achieved by the decreased collector-base junction capacitance. A new bipolar integrated circuit using SST gave a 63 ps/gate propagation delay time and 0.043 pJ/gate speed-power product.