bluuebunny/crossref_metadata_2025 huggingface dataset:
Operation and Stability of SnO2 Gas Sensors
Authors: Tischer Peter , Pink Hans , Treitinger Ludwig
Published: March 2014

Solid state gas sensors based on thin films of SnO2 can be very sensitive to small amounts of hazardous gases like hydrocarbons and carbonmonoxide. There are two models to explain the observed change in conductance, when the sensors are exposed to the gases: (1) Adsorption of the gas molecule at the surface and electron transfer from the gas molecule to the SnO2 or (2) adsorption of the gas followed by a reaction of the gas with previously adsorbed oxygen. The conductivity change is caused by the released electron which was captured by the oxygen during its adsorption. Experiments were carried out which support the second model. In order to get a stable gas sensor it is necessary to keep the surface of the SnO2 thin film in such a condition that the oxygen adsorption/desorption process can operate for a long time.
High Efficiency Silicon Solar Cells Using Minority Carrier MIS Structures
Authors: Godfrey R. B. , Green M. A.
Published: March 2014

Minority carrier Metal-Insulator-Semiconductor (minMIS) devices are electronically equivalent to ideal p-n junction diodes. Solar cells fabricated using minMIS structures have advantages over actual p-n junction cells. Grating minMIS cells with the semiconductor surface between the grating lines inverted produce the most efficient devices. Record V
oc's for Si cells of 655 mV have been obtained on FZ Si substrates, with efficiencies over 17.5% being achieved for both polished and textured surface cells. Using large grain polycrystalline Si substrates, efficiencies of 13.3% have been obtained which are the best for this material.
Design Parameters of a-Si: H High-Voltage Photovoltaic Cells
Authors: Okamoto Hiroaki , Nitta Yoshiteru , Hamakawa Yoshihiro
Published: March 2014

An optimum design for the amorphous silicon high-voltage photovoltaic cells composed of horizontally multi-layered p-i-n cells has been studied. A series of technical data on the design parameters and the device physics for the multi-layered cell are presented. Newly designed cell shows the open circuit voltage V
oc nearly proportional to the number of unit p-i-n junction with almost constant conversion efficiencies of around 4%. Attempts have been made up to ten p-i-n layered cells with a V
oc of 4.5 volts. Another new performance as an arbitrary spectral photosensor having a structure of double p-i-n junctions is proposed.
Si and GaAs SIS Heterostructure Solar Cells Using Spray-Deposited ITO
Authors: Sharma P. P. , Anthony T. C. , Ashok S. , Fonash S. J. , Tongson L. L.
Published: March 2014

A systematic study of semiconductor-insulator-semiconductor (SIS) solar cells has been undertaken on n-type Si and GaAs using spray-deposited indium-tin oxide (ITO) for the window layer of the heterostructure. The optical and electrical characteristics of the ITO layer as well as the thickness of the I-layer have been optimized to yield the following photovoltaic parameters on 1 Ω-cm n-Si: V
oc=0.52 V, J
sc=31.5 mA/cm2 (adjusted for Ag grid area), FF=0.70 and effective area η=11.5%. The dark I-V and C-V characteristics have also been evaluated to identify the mechanisms of barrier formation and current flow.
A Comparative Study of Cu2S–ZnxCd1-xS and Cu2S–CdS Thin Film Solar Cells Prepared by Solid State Reaction
Authors: Tomar M. S. , Garcia F. J.
Published: March 2014

We report here all polycrystalline thin film solar cells of Cu2S–Zn
x
Cd1-x
S and Cu2S–CdS prepared by solid state reaction. The efficiencies in the range of 4 to 5% have been obtained without antireflection coating. The improvement in open circuit voltage is observed in Cu2S–Zn
x
Cd1-x
S cell with little sacrifice in short circuit current. A comparison is also made with the solar cell Zn
x
Cd1-x
S–Cu2S prepared by spray pyrolysis and the electrical conversion efficiency about 1.0% is obtained.
Fabrication of DC-SQUIDs and Their Characteristics for Digital Applications
Authors: Hasuo Shinya , Suzuki Hideo , Dazai Koichi
Published: March 2014

This paper presents a design theory of DC-SQUID type Josephson tunnel junctions. Discussions are focused on the experimental verification of calculated threshold characteristics of the DC-SQUIDs for various device parameters. DC-SQUIDs designed here have been applied to the flux quantum memory cell and also to the full adder circuit, and they have been successfully operated as expected.
Current Injection Logic Gate with Four Josephson Junctions
Authors: Takada Susumu , Kosaka Shin , Hayakawa Hisao
Published: March 2014

A novel current switching Josephson logic gate in which four junctions are connected in a loop is described. This four-junction logic gate can reduce an inductance included in the loop as small as possible, so that the higher switching speed and the smaller device size is expected. The switching threshold and the switching characteristics of the gate are investigated both theoretically and experimentally. Logic circuits based on the gates are also experimentally demonstrated.
Impurity Content Determination in Si by Exciton Decays
Authors: Hammond R. B. , Silver R. N.
Published: March 2014

We report a new method in photoluminescence for determining impurity content in Si. Recently a kinetics model has been developed which explains the low temperature (\lesssim20°K) decays of free (FE) and bound (BE) excitons in Si. Using this model, it is possible to determine absolute impurity concentrations in P and B doped Si from temperature dependent exciton decays.
Characterization of Residual Impurities in Highly Pure Si Crystals by Photoluminescence Technique
Authors: Tajima Michio , Yusa Atsushi , Abe Takao
Published: March 2014

The residual impurities in highly pure Si crystals have been evaluated by the photoluminescence (PL) technique. The PL method makes it possible to identify the species of donor and acceptor impurities in the parts-per-trillion atomic (ppta) range and to determine their respective concentrations. The PL analysis of the float-zoned (FZ) ingot slightly contaminated by Al shows that the Al content increases greatly from the head to the tail, while the P and B contents are hardly changed. This corresponds with the variation of the segregation effect. The purification process by multipass vacuum FZ is also evaluated by the PL technique. The Ga components appear only in the starting material and the P content decreases greatly with pass number, while the B content decreases slightly. The PL analysis directly confirmed that this purification process is due mainly to the evaporation effect.
Polycrystalline Silicon Ribbons Made by Rapid Quenching Methods
Authors: Tsuya Noboru , Takeuchi Toshio , Arai Ken Ichi , Ohmori Kenji , Ebina Atsuko , Takahashi Tadashi , Kuroiwa Akihiko , Ojima Teruhiko
Published: March 2014

Polycrystalline silicon ribbons were prepared by Roller Quenching Methods. Ribbons obtained were produced at an ultra high speed about 20 m/sec, and the size was 20 µm to 200 µm in thickness and 1 mm to 50 mm in width. Microscopic observations of etched ribbon surface showed that the average grain size were 20 µm to 30 µm. Cross sectional view showed the ribbons in columnar grain structure. Any unwanted impurity was undetectable by an Auger analysis except very thin oxygenated layer on the surface of ribbons. The active carrier concentration of the ribbons was nearly the same with the doped impurity concentration from 1014/cm3 to 1020/cm3, and the Hall mobility parallel to the ribbon axis and perpendicular to the ribbon plane was 1 to 150 cm2· V-1· sec-1 and 700 cm2· V-1· sec-1, respectively. A solar cell using the present ribbon was made by a thermal diffusion method. The satisfactory diode characteristics and the conversion efficiency of about 5% were obtained.
(Invited) Integrated Acoustooptical Circuits for Real-Time Wideband Signal Processing
Authors: Tsai Chen S.
Published: March 2014

This paper presents a selective review of the progress on the realization of integrated acoustooptical circuits and some of the potential applications of such integrated acoustooptical circuits in real-time wideband signal processing.
Deposition of Silicon Nitride Films by High Rate Reactive Sputtering
Authors: Hoshi Youichi , Naoe Masahiko , Yamanaka Shun-ichi
Published: March 2014

Amorphous silicon nitride fims have been deposited at a high rate on the substrate without extreme rise of temperature by dc reactive sputtering in the atmosphere of a mixed gas of argon and nitrogen using a planar magnetron type of sputtering apparatus. The composition and deposition rate of the films were strongly depended on the partial pressure of nitrogen P
N2. Deposition rate and the content of silicon in the films decreased with increasing P
N2 especially in the range of P
N2=3∼5 m Torr and became nearly constant in the range of P
N2>5 m Torr. The refractive index, etch rate, resistivity, infrared absorption, transmittance and latent stress of obtained films were determined. The films deposited in the atmosphere of P
N2>5 m Torr exhibited excellent properties even if they were deposited at very high deposition rate above 1000Å/min.
Photovoltaic Properties of a Si–F–H and a·Si–H Prepared by DC Glow Discharge
Authors: Konagai Makoto , Miyamoto Hiroshi , Takahashi Kiyoshi
Published: March 2014

Amorphous Si–F–H films were prepared by DC glow discharge in an atmosphere of SiF4+H2. Optical and electrical measurements have been performed to evaluate the film quality. The photoconductivity of a ·Si–F–H films under sunlight is identical with a·Si–H films produced from SiH4 and Δσph obtained is 4×10-4 (Ωcm)-1. The initial Schottky barrier a·Si–F–H solar cell showed the efficiency of 1% under simulated AM1, 100 mW/cm2 insolation. Furthermore, the fill factor of solar cells is related to the minority carrier diffusion length in the undoped a·Si layer.
An Amorphous-Silicon Film Usable at High-Temperature –Annealing Properties of a New Fluorinated Amorphous-Silicon–
Authors: Matsumura Hideki , Nakagome Yoshinobu , Furukawa Seijiro
Published: March 2014

This is first report on an amorphous-silicon in which only fluorine atoms work as terminator of dangling bonds. This fluorinated amorphous-silicon is produced by radio-frequency sputtering in mixture of Ar and SiF4 gases, and variation of its fluorine content after annealing is measured by backscattering method together with variation of its temperature dependence of conductivity. As results, it is concluded that both fluorine content and temperature dependence of conductivity are kept unchanged even after 600°C annealing, and that this fluorinated amorphous-silicon is high-temperature usable.
Control of Optical Gap in a-SixC1-x: H Alloy Films Produced by Reactive Sputtering Method
Authors: Katayama Yoshifumi , Shimada Toshikazu , Usami Katsuhisa , Ishioka Sachio
Published: March 2014

Hydrogenated amorphous silicon-carbon alloy (a-SixC1-x: H) films are prepared by simultaneous if reactive sputtering of silicon and graphite in a H2–Ar gas mixture. The optical gap E
0 of a-Si
x
C1-x
: H depends on alloy composition x and preparation conditions. The optical gap E
0 of a-Si
x
C1-x
: H prepared under a same condition is ∼1.7 eV at x=1.0 (a-Si: H), increases with the decrease in x, reaches a maximum value of 2.2 eV at x=0.6 and then decreases with decrease in x, reaching ∼1.4 eV at x=0 (a-C: H). For films prepared at lower substrate temperature, the optical gap becomes larger. This behavior of the optical gap is discussed referring to the results of X-ray photoemission spectroscopy, infrared absorption measurements, etc., on a-Si
x
C1-x
: H.
Rapid Quenched Ribbon-Form Silicon
Authors: Tsuya Noboru , Arai Ken Ichi , Takeuchi Toshio , Ojima Teruhiko , Kuroiwa Akihiko
Published: March 2014

Morphological and crystallographical experiments of the rapid-quenched ribbon-formed silicon were studied with X-ray diffraction and microscopic observation on chemically etched ribbon surface. The rapid-quenched silicon ribbon is columnar structure polycrystalline without prominant preferred crystalline orientation. Average grain size of the silicon ribbon is 20 µm. Conductivity and Hall measurements showed, active carrier concentration was nearly equal to the doped impurity concentration in charge material. A conversion efficiency of 5% (94 mW/cm2) is obtained for an epitaxial solar cell on boron 6×1017/cm3 doped silicon ribbon.
A New Model for the Carrier Transport in Amorphous Si: H Schottky Barrier Diodes
Authors: Okushi Hideyo , Yamasaki Satoshi , Nakagawa Katsumi , Matsuda Akihisa , Matsumura Mitsuo , Tanaka Kazunobu , Iizima Sigeru
Published: March 2014

In order to interpret carrier transport in an amorphous silicon Schottky barrier, a new band diagram is proposed. By introducing a phenomenological theory based on the model, relationships between the diode characteristics and the gap states of a-Si: H are discussed. The main results deduced from the theory are as follows: (1) The space-charge density of the depletion region in the barrier is determined mainly by the gap states near the Fermi-energy. (2) The transient space charge limited current flowing when a high forward voltage is applied, decays through the carrier trapping process at the gap states near the Fermi-energy. (3) The breakdown voltage of the diode is closely related with the space-charge due to the localized states at the band tail in the vicinity of a-Si: H/metal interface. Primary experimental results are also presented and discussed.
Amorphous Si Photovoltaic Cells and Cell Module (Integrated Cell Module)
Authors: Kuwano Yukinori , Imai Terutoyo , Ohnishi Michitoshi , Nakano Syoichi , Fukatsu Takeo
Published: March 2014

A new type of the integrated a-Si: H photovoltaic cell module has been developed. The optimization of the cell parameters and dimensions were experimentally determined. The best conversion efficiency was 3.2%. The output power of the p-i-n cell was nearly equal to or larger than that of a crystal Si cell in fluorescent lighting.
High Efficiency AlxGa1-xAs–GaAs Solar Cells with High Open-Circuit Voltage and High Fill Factor
Authors: Yoshida Susumu , Mitsui Kotaro , Oda Takao , 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.
A high conversion efficiency of about 20% at air mass 1.0, with a high open-circuit voltage (1.00–1.02) and a high fill factor (0.82–0.85), was reproducibly obtained together with the reduction of the dark current.
To reduce the dark current, the p-n junction depth (width of the p-GaAs region) was chosen near 3–5 µm below the Al
x
Ga1-x
As–GaAs interface. The junction depth was controlled by varying the soaking time, during which the substrate was soaked isothermally in the saturated Al–Ga–As Zn doped melt.
Preparation and Properties of InGaAsP p-n Junction for Fabrication of Photodetectors in Optical Communication Systems
Authors: Yamazoe Yoshimitsu , Sasai Yoichi , Nishino Taneo , Hamakawa Yoshihiro
Published: March 2014

The opto-electronic properties of diffused InGaAsP p-n junction diodes have been investigated for the fabrication of well-controlled photovoltaic detector in the near-infrared spectral region. These diodes have been fabricated by Zn or Cd diffusion into n-type undoped InGaAsP LPE layers, and it has been found that Cd diffusion into InGaAsP is easier to control than Zn diffusion. The influence of residual impurities or vacancies in InGaAsP LPE layers can be seen in the current-voltage characteristics of the diffused p-n junction in both the current directions. Photoresponse of Cd-diffused diodes shows larger signals than Zn-diffused diodes in the higher energy side of the bandgap. The acceptor levels have been also measured by photoluminescence.
Fundamental Properties of MIS Solar Cells
Authors: Matsunami Hiroyuki , Matsumoto Shigenori , Tanaka Tetsuro
Published: March 2014

Fundamental properties of the MIS (Pt–SiO2–n Si) solar cell are measured, and the role of the insulator is clarified. From current-voltage and capacitance-voltage characteristics, the difference in the MIS and Schottky cells is elucidated. The inversion region exists at the interface between the oxide and the semiconductor, and the holes in the inversion region have an influence on the characteristics. Photovoltaic performances of the MIS cell such as the illumination intensity dependence, spectral response and temperature dependence are discussed.
Solution-Grown Silicon Solar Cells
Authors: Ito Kentaro , Kojima Kunio
Published: March 2014

Silicon pn junction solar cells with the conversion efficiency up to 9.0% were prepared by a liquid phase epitaxial technique in which aluminum was used as a solvent. The estimated surface recombination velocity of the solar cells was one or two orders of magnitude less than that of the conventional silicon solar cells. The fabrication method proposed in this paper is a low temperature process inherently and provides the cells free from the so-called “dead region.”
Development of High Efficiency Epitaxial Silicon Solar Cells
Authors: Usami Akira , Ishihara Shin-ichiro , Sugano Masahide
Published: March 2014

The optimum fabrication conditions for npp+ and n+ npp+ types epitaxial silicon solar cells are described. Epitaxial p-base and n-surface npp+ and n+ -diffused n+ npp+ solar cell structures were grown on both (111) and (100) oriented single crystalline silicon substrates. All the cells have no A.R. coating. The optimum conditions for high efficiency cells are following; resistivity of the p-epitaxial region is the range of 0.1–0.5 ohm-cm and the thickness of it is about 30µm or below, and the n+ npp+ structure is the important condition. Maximum efficiency of 10.0% has been obtained for both the npp+ cell whose resistivity of the p-epitaxial layer was 0.5 ohm-cm and the n+ npp+ cell with 3 ohm-cm.
Silicon Epitaxial Solar Cells by Ion-Plating Deposition
Authors: Saito Takeshi , Noguchi Kesao , Kaneko Sctsuo , Terasawa Yoshizumi
Published: March 2014

Ion-plating deposition has been studied for silicon film groth as a low temperature solar cell fabrication process. The lowest epitaxial temperature was found out about 700°C by an electron diffraction study. Junction solar cells were fabricated by depositing n+-type silicon films onto (100) p-type silicon substrates and showed up to 11% photovoltaic conversion efficiency at AM2.
Paint-on-diffusant SnO2/n+-p Si Heteroface Solar Cell
Authors: Takakura Hideyuki , Choe Moon-Soek , Hamakawa Yoshihiro
Published: March 2014

The optimum design of the SnO2/n+ -p Si heteroface solar cell is systematically investigated and substantial improvements in energy conversion efficiency are reported. Cells were fabricated by the paint-on-diffusant method for the junction formation and CVD method for the SnO2 film deposition. Fabrication processes are much simpler and this solar cell has much higher conversion efficiency than ordinary p-n homojunction solar cells. Efficiency of 14.0% has been obtained for 1×1 cm2 cell under 72 mW/cm2 sunlight.
Hydrogen Implantation into CVD Amorphous Silicon
Authors: Suzuki Tohru , Hirose Masataka , Osaka Yukio
Published: March 2014

Hydrogen ions were implanted into phosphorus-doped CVD amorphous silicon at 20 keV with the dose of 5×1016 cm-2. The native defects in as-grown films were efficiently passivated by the implanted hydrogen atoms, after removal of implantation-induced defects by annealing at 300°C. As a result, the doping efficiency and photoconductive response were dramatically improved. The density of gap states for hydrogen implanted CVD amorphous silicon is estimated to be by about two orders of magnitude lower than that of as-grown one.
Effect of Delocalization of d-Electrons on the Optical Reflectivity Spectra of CuGa1-xFexS2 and CuAl1-xFexS2 Systems
Authors: Sato Katsuaki , Teranishi Teruo
Published: March 2014

Single crystals of CuGa1-x
Fe
x
S2 and CuAl1-x
Fe
x
S2 have been grown by the chemical transport reaction. Crystals with x<x
c were black while those with x≥x
c were golden-colored, where x
c=0.14 for CuGa1-x
Fe
x
S2 and x
c=0.12 for CuAl1-x
Fe
x
S2 Optical reflectivity spectra of these crystals have been measured using a microcomputer-controlled reflectance spectrometer.
The difference between black and golden crystals is quantitatively characterized; reflectivity at 1.5–3 eV region of the golden crystals is much higher than the black crystals. Absorption spectra obtained by the Kramers-Kronig analysis reveal that this reflectivity enhancement is associated with the broadening of d-orbital energies due to delocalization.
Natural Optical Activity of AgGaSe2
Authors: Horinaka Hiromichi , Sonomura Hajimu , Miyauchi Takeshi
Published: March 2014

A method for measuring the optical rotatory power in crystals which have both birefringence and optical activity effect is proposed. The rotatory power of AgGaSe2 is measured by this method. It is found that the optical rotatory power in the [100] direction sharply decreases from 237°/mm to 40°/mm with increase in wavelength, from 750 nm to 950 nm, at room temperature. AgGaSe2 is found to be optically isotropic at a wavelength of 811 nm, the rotatory power at this wavelength being 118°/mm.
Observation of Landau Levels and Two-Dimensional Energy Bands in CdSnAs2 by Electron Tunneling
Authors: Nakashima Yuichi , Kawamata Toshinori , Shirakawa Tsuguru , Nakai Junkichi
Published: March 2014

By tunneling measurements, it has been demonstrated experimentally, for the first time, that surface bound states of electrons localized in an accumulation layer exist at the CdSnAs2-oxide interface. In a CdSnAs2-oxide-Pb junction whose semiconductor electrode has a carrier concentration n=4.4×1018/cm3, the binding energies of the ground and the excited states are 44 meV and 16 meV, respectively. The Landau level structure of the two-dimensional energy band associated with the excited bound state has been observed in magnetic fields up to 55 kG. The effective mass of the electric subband is found to be m
0
*=(0.019±0.002)m
0.
Quaternary Defect Chalcopyrite Compounds I III IV VI4
Authors: Woolley J. C. , Goodchild R. G. , Hughes O. H. , Lopez-Rivera S. A. , Pamplin B. R.
Published: March 2014

The crystallographic and optical properties determined for twelve compounds of the form I III IV □Se4 are reviewed, the compounds being those formed by combinations of the elements I Cu, Ag: III Al, Ga, In: IV Ge, Sn. It is found that all of the compounds have the chalcopyrite structure and lattice parameter values have been determined for each. These values are compared with those of the corresponding ternary chalcopyrite I III Se2 compounds and a systematic variation between the parameters for ternary and quaternary compounds is shown. Energy gap values have been determined for the twelve compounds by optical absorption measurements. These also have been compared with the values for the corresponding ternary compounds and again a systematic variation shown. Finally, reflectance spectra have been determined as a function of temperature for a single crystal sample of CuGaSn □Se4 and hence the temperature variation of the three valence band-conduction band gaps investigated.
A Model Semiconductor for Multinary Compounds
Authors: Garbato L. , Manca P. , Mula G.
Published: March 2014

A simple model derived from the LCAO method is described and applied to a number of elemental, binary and ternary semiconductors. Due to some simplifying assumptions about the interaction integrals the only input parameters are the nuclear effective charges of the constituent atoms and the interatomic distances. The model can be easily extended to multinary compounds.
A particularly interesting feature of the theory is that the volume dependence of physical quantities such as the minimum energy gap is given explicitly and found in reasonable agreement with the experiment. The connection of the model with the pseudopotential method is explicitly analyzed and it has been found that the use of nuclear effective charges amounts to the choice of a reasonable oneparameter pseudopotential.
Crystal Chemistry and Vapor Growth Application to Ternary Semiconductors
Authors: Gibart Pierre , Goldstein Léon , Dormann Jean Louis
Published: March 2014

Many ternary semiconductors do not melt congruently. For these compounds, vapor could be a reliable method to grow single crystals, although it may introduce deviations from the stoichiometry and unintentional doping. The vapor transport of ternary compounds can be predicted with good accuracy from a thermodynamic analysis when data are available.
Most chalcopyrite semiconductors have been grown from vapor. To overcome the difficulty of growing chromium chalcogenide spinels that results from the low vapor pressure of chromium chlorides, H and Cl were used as transport components to grow FeCr2S4 and CoCr2S4. HgCr2Se4 crystals were grown using Al and Cl; a volatile complex, CrAl2Cl8, is formed that allows the transport of chromium. As-grown ternary semiconductors have vacancies of the volatile element. Annealing of vapor grown ternary semiconductors significantly changes the electronic properties.
Influence of Nonstoichiometry on the Properties of Undoped CdCr2Se4
Authors: Kiyosawa Teruo , Masumoto Katashi
Published: March 2014

The behaviour of the deviation from stoichiometry in the ferromagnetic semiconductor CdCr2Se4 is studied.
Specimens of undoped CdCr2Se4 were annealed under variously controlled Se vapor pressures in coexistence with CdSe or Cr2Se3 (or Cr3Se4). The electrical resistivity, Hall coefficient, lattice parameter and X-ray diffraction intensities were measured at room temperature on these specimens. The dependence of the properties on Se vapor pressure and CdSe activity was disclosed. The predominant acceptor-type defect due to the deviation from stoichiometry is found to be a Cd ion substituted for a Cr ion.
Electronic Band Structure of Magnetic Semiconductors with Spinel Structure
Authors: Kambara T. , Oguchi T. , Yokoyama G. , Gondaira K. I.
Published: March 2014

The electronic band structures of ferromagnetic semiconductors CdCr2S4, CdCr2Se4, and HgCr2Se4 are calculated self-consistently by the DV-Xα method. The general features of the band structures are quite similar for three substances except for the relative positions of the 3d bands: Each structure consists of relatively narrow valence bands, fairly wide conduction bands, and very narrow d bands. The d
ε and dγ bands for up-spin lie in the energy region near the top of the valence bands and around the bottom of the conduction bands, respectively, and both d bands for down-spin fall in the conduction bands. The fundamental energy gap at the Γ point is 2.6, 2.3 and 1.8 eV for CdCr2S4, CdCr2Se4, and HgCr2Se4, respectively. The spin polarization of the Cr-3d orbitals is about 3.5, while the spin polarization of the valence p orbitals of a chalcogen ion has the opposite sign.
Properties of CuInSe2 Thin Film Semiconductors
Authors: Isomura Shigehiro , Kaneko Hideki , Tomioka Shinji , Nakatani Isao , Masumoto Katashi
Published: March 2014

Thin films of the chalcopyrite compound CuInSe2 are prepared by D.C. sputtering and by vacuum evaporation on glass substrate. The films prepared by the two methods show remarkable differences in preferential growth orientation and other properties. In this paper, the physical and electronic properties of CuInSe2 films are described, and the influences of the growth conditions on their properties are discussed.
Magnetic Semiconductors: New Interpretation
Authors: Miyatani Kazuo
Published: March 2014

A simple crystallographic model based upon lattice compression ratios is applied to analyze and characterize bonding behavior, bandgap energy, and related basic properties of rare earth chalcogenides and chalcogenide spinels. The basic properties of typical magnetic semiconductors, EuX and AB2X4 (X=O, S, Se, and Te) are discussed relative to this model. Effects of dopants on the magnetic, optical, and electrical properties are analyzed using available data. The extrinsic properties of chalcogenide spinels are interpreted with newly developed ionic distributions.
Differences between EuX and chalcogenide spinels are discussed. Further examination of available models is necessary to explain resistivity anomaly in chalcogenide spinels. The present analysis provides guidance for selecting room temperature magnetic semiconductor material.
Origin of Semiconductive Conduction in Fe1-xCuxCr2S4(0<x<0.5): An Interpretation of Mössbauer Spectra of Fe0.98Cu0.02Cr2S4
Authors: Ando Koji , Nishihara Yoshikazu
Published: March 2014

Mössbauer spectra of Fe0.98Cu0.02Cr2S4 are measured, and analyzed by a model of the electron exchange between Fe2+ and Fe3+. Major features of the spectra are explained by this model. Large amount of Fe3+ is derived from the analysis. Outlines of the compositional dependences of the electrical resistivity and the Seebeck coefficient in the system Fe1-x
Cu
x
Cr2S4(0<x<0.5) are explicable by the compositional change of the densities of Fe2+ and Fe3+. The electrical conduction comes mainly from the 3d band of iron. This model leads to two different mechanisms of the semiconductive conduction in this system. One is the electron transfer from Fe2+ to Cr2+. The other is the change in the mobility. Both mechanisms seem to contribute in this system.
Solid-Solution Oxides for Storage-Battery Electrodes
Authors: Goodenough J. B. , Mizushima K. , Takeda T.
Published: March 2014

Insertion compounds contain a mobile cation of variable concentration over a wide range of solid solution. Charge compensation is achieved by a variation of mobile-electron concentration in the host matrix. Such mixed ionic/electronic conductors are of practical interest as electrodes in secondary batteries and electrochromic displays. Oxides containing transition-metal ions in unusually high valence states can be prepared by room-temperature extraction of mobile cations from such structures. Some properties of the systems Li1-y
CoO2 and Na1-y
CoO2 are presented.
Band Structure and Optical Properties of In1-xGaxAsyP1-y
Authors: Kelso S. M. , Aspnes D. E. , Olson C. G. , Lynch D. W. , Nahory R. E. , Pollack M. A.
Published: March 2014

Dielectric function spectra in the visible-near uv and energy derivative reflectance spectra in the vacuum uv spectral ranges are reported for In1-x
Ga
x
As
y
P1-y
at compositions between y=0 and 1 lattice-matched to InP. Analysis of these spectra yields bowing parameters for the valence-conduction band critical points E
1, E
1+Δ
1, and E'0, estimates of core exciton binding energies, and the ordering of the lower conduction band minima at L and X.
Semiconductor Materials for 2∼4 µm Region Optical Sources and Room Temperature Operation of InGaAsSb/AlGaAsSb DH Lasers
Authors: Kobayashi Naoki , Horikoshi Yoshiji , Uemura Chikao
Published: March 2014

Two III-V quaternary systems, In
x
Ga1-x
As
y
Sb1-y
lattice-matched to GaSb and InAs1-x-y
P
x
Sb
y
lattice-matched to InAs, were investigated to fabricate double heterostructure (DH) lasers for longer wavelength optical sources as compared with InGaAsP/InP DH lasers. DH lasers with an emission wavelength around 2 µm were fabricated by using InGaAsSb with GaSb enriched composition as an active layer and AlGaAsSb as confinement layers. The pulsed room temperature operation at 1.8 µm wavelength was performed for In0.05Ga0.95As0.04Sb0.96/Al0.2Ga0.8As0.02Sb0.98 DH lasers fabricated by liquid phase epitaxy. For 3∼4 µm wavelength optical sources, it has shown that InAsPSb is one of the most promising materials.
Characterization of Defects in InP-InGaAsP Double-Heterostructure Materials
Authors: Yamaguchi A. , Komiya S. , Nishitani Y. , Akita K.
Published: March 2014

Defects in (100) and (111)B InP-InGaAsP double-heterostructure materials for 1.3 µm optical devices which were grown by liquid phase epitaxy were investigated by spatially resolved photoluminescence (SRPL) with a resolution around the wavelength. The defects observed in SRPL images were identified by X-ray diffraction topography and etching techniques. An exact correspondence between dark spots and dislocation clusters and that between dark lines and misfit dislocations are found. SRPL features corresponding to local absence of InGaAsP, meniscus lines, inclusions and interface morphology have also been identified.
Photoconductivity from Free Carrier Absorption in Mercury-Cadmium-Telluride
Authors: Weber Bruce , Kulpa Stanley M.
Published: March 2014

We report the development of the first hot-electron photoconductive detector using crystals of the alloy-semiconductor mercury-cadmium-telluride, [Hg1-x
, Cd
x
]Te. When the detector is irradiated with near-millimeter wave radiation, sensitivity is observed spanning the wavelength region from 0.12 to 4.4 mm. At a temperature of 4.2 K and a wavelength of 2.5 mm, the noise equivalent power is observed to be 9.7×10-11 W/√Hz with a response time less than 40 ns. The voltage responsivity decreases by approximately 50-percent for each 5 K increase in temperature above 4.2 K. Comparative performance measurements are reported for various InSb crystals.
Low-Temperature Anomalies in Photoconductivity of Indium Doped Lead-Tin-Telluride
Authors: Penchina Claude M. , Klein A. , Weiser K.
Published: March 2014

Pb1-x
Sn
x
Te (LTT) doped with indium is found to have some unusual photoconductive and transport properties at low temperatures: These include such effects as persistent photoconductivity, negative photoconductivity, and an anomalous temperature dependence of the Hall effect. A single model involving electronic transitions between various charge states of indium, with negative correlation and large lattice relaxation, is used as a basis for discussion of these various anomalies.
Hopping Conduction and Magnetic Behavior in VxCr3-xS4(0≦x≦3)
Authors: Tazuke Yûichi
Published: March 2014

Electrical resistivity is measured between 4.2 K and 295 K on polycrystalline samples of V
x
Cr3-x
S4 with defect nickel-arsenide structure. A metallic conduction is observed in 0.0≦x≦0.4 and 2.75≦x≦3.0, and a nonmetallic conduction is observed in 0.6≦x≦2.5. In the latter, the activation type conductivity σ∼exp
(-E
A/k
T) is observed only above ∼200 K. Variable range hopping conduction σ∼exp
{-(Q/k
T)1/4} is observed at low temperature in 0.6≦x≦1.75. The conduction behavior has several characteristic features of the Anderson transition. A discussion is made about the conduction behavior in conjunction with the magnetic property.
XPS Valence-Band Densities of States of Ternary Chalcogenide Crystals: Application to Tl3AsSe3
Authors: Kowalczyk S. P. , Kraut E. A. , Ewbank M. D. , Harrison W. A.
Published: March 2014

We report the results of an X-ray photoelectron spectroscopic (XPS) investigation of the total valence-band density of states (VBDOS) of Tl3AsSe3, a ternary sulfosalt-type crystal. The XPS-VBDOS consists of three regions. The upper portion of the VBDOS, Region I, is approximately 8 eV wide and exhibits three distinct broad features (at ∼1.7, ∼4, and ∼6.5 eV below the valence-band maximum). This region is derived mostly from Se 4p orbitals with some contribution from Tl 6s orbitals. Region II lies to the low binding-energy side of and is partially obscured by the Tl 5d core level. These bands of mostly As 4s origin are broad and centered approximately at 10 eV. The last region (III) consists of the very intense Tl 5d
3/2 and Tl 5d
5/2 core levels at 14.8 and 12.6 eV below the top of the valence-band maximum, respectively. These levels probably obscure the much weaker, lowermost, nearly core-like Se 4s derived bands. These results are in qualitatively good agreement with our recent LCAO calculations with the most serious deviation being the position of the lowermost band.
Electrical Properties of TlBiTe2
Authors: Valassiades O. , Economou N. A.
Published: March 2014

Electrical measurements performed on single crystals of TlBiTe2 by the van der Pauw method indicate that it behaves anisotropically in resistance, while the Hall coefficient is isotropic. There is a slight temperature dependence indicating that the nominal concentration increases with temperature. The mobility shows a power law dependence on temperature with the slope depending on the temperature interval. At 672 K an abrupt change in resistivity and Hall coefficient is observed, above which the material behaves isotropically suggesting a transformation of the type D3d→Oh.
Crystal Growth and Properties of Quinary Chalcopyrite Compounds
Authors: Paorici C. , Romeo N. , Tarricone L. , Zanotti L.
Published: March 2014

The quinary compound CuGa
x
In1-x
S2y
Se2(1-y) was prepared as a single crystal by means of a vapor-phase chemical-transport procedure. Complete solid solutions were obtained within the entire range of compositions (0\leqslantx\leqslant1;0\leqslanty\leqslant1). The crystallographic structure was seen to be that of chalcopyrite. The electrical resistivity and the Hall mobility were investigated in several samples with different composition obtaining values within the intervals 10-1∼102 Ω · cm and 5∼10 cm2V-1s-1. The results of optical investigations aimed at correlating the solid-solution composition and the width of the forbidden energy gap are reported.
Possibility of Blue Light Emitting Diode in CuAl1-xGaxS2/ZnS Heterojunction
Authors: Yamamoto Nobuyuki
Published: March 2014

Among many I-II-VI2 chalcopyrite semiconductors, CuAlS2 is an only prospective candidate for blue LED application. Our recent observation of purple to green photoluminescence in CuAl1-x
Ga
x
S2 mixed alloys urges to prepare a heterojunction of p-CuAl1-x
Ga
x
S2/n-ZnS by liquid epitaxial growth. After a brief review of luminescence properties and LED fabrication of CuGaS2, photoluminescence properties and possibility of a blue LED of CuAl1-x
Ga
x
S2 are described.
A High Current Gain and High Speed Power Gate Associated Transistor
Authors: Kondo Hisao , Yukimoto Yoshinori
Published: March 2014

Design consideration and electrical characteristics of power Gate Associated Transistors (power-GATs) are described.
Gate spacing and its depth were critical to reconcile high current gain and high switching speed with high collector emitter breakdown voltage by means of minimum gate area. To retain high current gain and high switching speed in the region of high collector current density, a multi-emitter structure was employed and impurity concentration and thickness of both base and collector regions were also optimized.
By optimization of design parameters, a power-GAT was fabricated having collector emitter sustaining voltage of 630 V, collector current rating of 50 A, common emitter current gain of 30 and rise time of 0.1 µs.
150 V High Voltage Linear IC Technology
Authors: Imaizumi Ichiro , Kimura Masatoshi , Yoshimura Masayoshi , Yamaguchi Takashi
Published: March 2014

A new structure, called a Semi-Well Isolation (SWI) IC structure, suitable for high voltage IC and its process technologies are developed for 150 V consumer ICs. The SWI structure has an epitaxial layer of two different thicknesses, and different impurity profiles if desirable. High voltage elements are formed in the thick portion, the isolation region and small signal elements are formed in the thin portion. As results, both high voltage transistors and low voltage ones are optimized separately on the same chip.
A color TV vertical deflection output IC, which operates from a transformerless voltage source, is developed using the SWI structure.
Flat Emitter Transistor with Self-Aligned Base
Authors: Fujita Tsutomu , Yamada Haruyasu , Komeda Tadao , Takemoto Toyoki
Published: March 2014

A flat emitter transistor with a self-aligned base (FLET) has been developed to realize a high speed and low power dissipation bipolar LSI. This FLET has a flat bottom emitter and eliminates parasitic capacitance in the side wall. Accordingly, current gain (h
FE) is almost independent of the emitter size and shape. Moreover, high cut-off frequency (f
T) and high h
FE can be obtained in low current region. The FLET also has an inactive base of high impurity density formed extremely near the emitter region. As a result, the base resistance can be lowered even though single line base structure is used. This base contact structure enables the reduction of C
TC and C
TS. The divider using FLET operated at frequencies up to 1.3 GHz. The power dissipation was 125 mW, being one fifth that of the conventional divider.
(Invited) Fiber Optics R & D in the 1980's
Authors: Kao C.
Published: March 2014

Optical fiber communication systems will serve, on a large scale, in a wide range of applications in the 80's decade. After almost two decades of research and development into the associated technologies, the advantages, both technical and economic, have been characterized and reliability assured.
In this paper the technological events and market trends of the 1970's are briefly reviewed, leading to an attempt at predicting the events of the 1980's. Telecommunication, computer, and sensor applications are seen flourishing and are to be complemented with specialized applications exploiting the electromagnetic interference freedom, small size, light weight, and high strength advantages of the fiber. The application in broadband distribution network, in particular, is socially and technologically important in the 1980's.
(Invited) Visible Semiconductor Laser
Authors: Susaki Wataru , Takamiya Saburo
Published: March 2014

The state-of-the-art visible semiconductor lasers are reviewed. The characteristics and reliability problems of ternary and quarternary lasers grown on GaAsP compositionally graded layers are presented. The lasing properties and operating life of the transverse mode stabilized AlGaAs visible lasers grown on close lattice matched GaAs substrates are described, particularly on transverse junction stripe (TJS) lasers. TJS lasers oscillate in a single longitudinal mode with the fundamental transverse mode, and have the very low threshold current of 20–30 mA for the wavelengths between 900 and 750 nm. Negligible degradation has been observed in TJS lasers with the lasing wavelength around 780 nm after 4500 hr life test at 50°C with the constant lasing output of 3 mW/facet.
Non-Destructive Analysis of the Si–SiO2 Interface by Electron Energy Loss Spectroscopy Study
Authors: Ito Toshimichi , Kataoka Yoshihide , Iwami Motohiro , Hiraki Akio
Published: March 2014

Thin SiO2 (up to ∼60 Å thick) grown thermally on crystal Si (111) and (100) substrates was examined without any destructive treatments such as ion sputtering and chemical etching by electron energy loss spectroscopy (ELS) technique. The non-destructive ELS measurements were based on an employment of tunable escape length (∼10 to several tens Å) of probing electrons with different energies of 0.2–2.3 keV. With incident energies above critical ones dependent on oxide thickness, the loss spectra indicated a new feature at the transition energy of ∼7.7 eV, which was identified to be associated with the Si–SiO2 interface, probably interfacial plasmons of the Si–SiO2 couple. The possible presence of roughness or undulation in the Si–SiO2 interface, which was considered to be a sharp one in the chemical structure, was discussed.
Effect of Long Term Stress on Hot Electron Trapping
Authors: Matsumoto Heihachi , Sawada Kokichi , Asai Sotoju , Hirayama Makoto , Nagasawa Koichi
Published: March 2014

The threshold voltage shifts through the long term stress are measured for IGFETs. The gate bias dependence shows that the hot electron trapping is affected strongly by the electric field in the gate insulator. The threshold voltage shift versus time is well explained with the simple theory modified by the effect of the trapped charge on the subsequent electron trapping. The access time shifts are measured for actual 16 Kbit dynamic MOS RAM's. The access time degradations correspond well relatively to the threshold voltage degradations for the IGFET's.
Isothermal Capacitance Transient Spectroscopy
Authors: Okushi Hideyo , Tokumaru Yozo
Published: March 2014

A new measurement method for deep levels in semiconductors is demonstrated, by which the measurement of the transient change of capacitance is performed under an isothermal condition (Isothermal Capacitance Transient Spectroscopy). The method allows us to construct a precise measurement and analysis system by a programmable calculator. Detailed experiment and analysis by the method in the case of Au-doped Si in dicate that the method is one of useful tools for spectroscopic analysis of deep levels in semiconductors.
(Invited) Optical, Electrical and Structural Properties of Plasma-Deposited Amorphous Silicon
Authors: Tanaka Kazunobu , Nakagawa Katsumi , Matsuda Akihisa , Matsumura Mitsuo , Yamamoto Hideo , Yamasaki Satoshi , Okushi Hideyo , Iizima Sigeru
Published: March 2014

Amorphous Si: H and Si: F: H films, doped as well as non-doped, have been prepared both by glow-discharge (GD) and reactive-sputtering (SP) methods, and their structural properties have been investigated systematically through X-ray diffraction, Raman scattering, EPMA and ir transmission measurements. Optical and electrical properties are discussed in relation with the contents of Ar, doped element (P), bonded H and dangling bonds and with film structure. It has also been demonstrated that high RF power deposition results in crystallization of Si: H films, independent of whether doped or non-doped, and their structure has been characterized as a mixed phase, consisting microcrystals (100-A size) embedded in amorphous network.
IR-OPFET: Infrared Sensor Using PbTiO3 Pyroelectric Film
Authors: Okuyama Masanori , Matsui Yasushi , Seto Hiroyuki , Hamakawa Yoshihiro
Published: March 2014

IR-OPFET having a structure of PbTiO3 thin film gate on Si FET has been fabricated. The pyroelectric property of a tiny PbTiO3 thin film provides a high speed infrared sensitivity with a wide wavelength range at room temperature. A typical performance as an IR-OPFET is that voltage responsivity R
v and detectivity D
* are 390 V/W and 3.5×105 cm√Hz/W, respectively, at 20 Hz under infrared irradiation coming through a Ge filter from an incandenscent lamp. The rise time of the response measured by one shot of CO2 laser pulse is estimated to be about 3.5 µsec.
An Improved Josephson Interferometer Memory Cell for Nondestructive Read-Out
Authors: Yamamoto Masafumi , Ishida Akira
Published: March 2014

An improved single flux-quantum Josephson interferometer memory cell which brought stable nondestructive read-out (NDRO) operation was proposed. The cell was constructed with an end-fed asymmetric two-junction interferometer, in which the bit operating current level could be set far above the critical point for stable NDRO operation. Damping condition for proper memory operation was studied by computer simulation. The NDRO operation was experimentally obtained for the McCumber damping parameter βc of 300–400.
A Two-Josephson-Junction Memory Cell with Nondestructive Readout
Authors: Kurosawa Itaru , Nitta Matsuo
Published: March 2014

A new-type Josephson junction memory cell with nondestructive readout (NDRO) is proposed. The cell consisting of a planar superconducting loop and two Josephson junctions, is selected by the coincident pulses on the vertical and horizontal lines. Its structure is simple and symmetric, and all drive currents are unipolar. Operations of the cell are considered on both threshold characteristics and potential energy of the cell circuit. Experimental results are given for threshold curves and operating regions, and also shown are the driving pulse sequence and the sense voltage for memory operation.