bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonstoichiometry in Ternary Oxides and Materials Science
Authors: Collongues R.
Published: March 2014

The phenomenon of nonstoichiometry has been extensively studied in binary and ternary oxides. It includes many different aspects strongly connected with order-disorder phenomena. The models developed for oxides have been successfully applied to other nonstoichiometric compounds. Besides its basic interest in crystal chemistry, the nonstoicbiometry is of outstanding significance in materials science. Some examples are described: high temperature superconductors, superionic conductors, lasers and non linear optical materials. Not only the properties but also the conditions of elaboration and crystal growth are strongly dependent on the nonstoichiometry.
Magnetoresistance in the Variable Range Hopping Conduction Regime in n-Type CuInSe2
Authors: Wasim S. M. , Essaleh L. , Galibert J. , Leotin J.
Published: March 2014

Conductions by variable range hopping mechanism following Mott's law in two different temperature ranges are observed in n-type CuInSe2. In low field the relative negative magnetoresistance follows the relation (Δρ/ρ0)∝B
2
T
-3/4, in agreement with the theories based on quantum interference. The variation of Δρ/ρ0 with B at higher values upto 6 T is also discussed.
Optical Absorption and Phase Transitions in CuGa(SxSe1-x)2 Alloys at High Pressure
Authors: González J. , Calderon E. , Capet F. , Aioouy L. , Chervin J. C.
Published: March 2014

The oprncal absorption edge of CuGa(S
x
Se1-x
)2 single crystals was measured as a function of hydrostatic pressure, covering the full stability range (0–30 GPa) of the chalcopyrite phase. For the full range 0≤x≤1, the direct energy gap exhibits a linear increase under pressure, with the corresponding gap deformafion potential being -3.9 eV for x=0, -4.5 eV for x=0.5 and -5.5 eV for x=1. From changes in the light transmission characteristic of the samples under pressure, structural first-order phase transitions were observed. On releasing pressure the observed irreversible shifts in the optical absorption are believed to be associated with the formation of new metastable semiconducting phases.
Luminescent and Photoconductive Properties of AgGa2.5In2.5S8 and CuGa2.5In2.5S8 New Semiconductors
Authors: Anedda A. , Serpi A. , Moldovyan N. A. , Tlginyanu I. M. , Ursaki V. V.
Published: March 2014

Results of a complex study of photoluminescence (PL), photoconductivity (PC) and photo-voltaic (PV) spectra in AgGa2.5In2.5S8 and CuGa2.5In2.5S8 single crystals are presented. The values of indirect (E
g
i=2.25 eV) and direct (E
g
d=2.60 eV, T=300 K) gaps in AgGa2.5In2.5S8 have been determined. PL spectrum of AgGa2.5In2.5S8 is shown to consist of two overlapping bands with the maxima at 1.57 and 1.95 eV (T=77 K), while CuGa2.5In2.5S8 is characterized by a single PL band, the position of its maximum (1.72–1.77 eV) depending upon the excitation power density. The radiative electron transitions in CuGa2.5In2.5S8 are assumed to occur from the quasicontinuously distributed traps below the bottom of the conduction band to an acceptor level with 0.07 eV activation energy.
Shallow Levels in CuInS2
Authors: Ueng H. Y. , Chang D. Y.
Published: March 2014

By correlating the various analytical results of Photo-Hall, Photoluminescence, and Differential Hall measurements with the stoichiometry, the related defect structure distributed in the forbidden gap of CuInS2 semiconductor in which the shallow levels were specified. We obtained four shallow donor levels are 11 meV, 18 meV, 31 meV and 38.5 meV and two more deep donor levels 70 meV and 145 meV below the conduction band edge for the n-CuInS2. The donor level located at 38.5 meV had been identified as sulfur vacancy, and other shallow levels were not identified. We also obtained that there are three acceptor levels as 0.11 eV, 0.155 eV and 0.17 eV above the valence band for the p-type CuInS2. The acceptor level located at about 0.105 eV and 0.155 eV above valence band had been identified. The acceptor level located at 0.17 eV above the valence band were also cognized by the Photo-Hall measurement. It could be identified such acceptor level as an electron trap.
Photoreflectance Characterization of CuAlSe2 Heteroepitaxial Layers Grown by Metalorganic Chemical Vapor Deposition
Authors: Shirakata Sho , Chichibu Shigefusa , Matsumoto Satoru , Isomura Shigehiro
Published: March 2014

Photoreflectance (PR) has been developed as a useful technique for the characterization of chalcopyrite heteroepitaxial layers. PR measurements at 77 K have been done on CuAlSe2 layers grown on GaAs and GaP substrates by means of the low-pressure metalorganic chemical vapor deposition technique. The analysis of the PR spectra in terms of transition energy, intensity and broadening parameter has led us to the successful characterization of the crystal quality, stress and the crystallographic orientation in the CuAlSe2 epitaxial layer.
Photothermal Effect in Compound Semiconductors CdInGaS4 and CdIn2S4
Authors: Toyoda Taro , Sorazawa Mitsumasa , Nakanismi Hisayuki , Endo Saburo , Irie Taizo , Shigenari Takeshi
Published: March 2014

Photothermal spectroscopy using thermistor is applied to study the heat generation by nonradiative processes of compound semiconductors CdInGaS4 and CdIn2S4 together with the optical absorption and reflectance measurements. It shows that the increases of heat generation are different from those of the total rate of optical energy absorption below the fundamental absorption edge regions for CdInGaS4 and CdIn2S4. The incident light power dependence of photothermal signal intensity using Ar ion laser is non-linear for CdInGaS4 and CdIn2S4.
First Fabrication of Low-Threshold AlGaAs/GaAs Patterned Quantum Wells Laser Grown on Si Substrate
Authors: Hasegawa Yoshiaki , Egawa Takashi , Jimbo Takashi , Umeno Masayoshi
Published: March 2014

A low-threshold AlGaAs/GaAs patterned quantum wells laser has been fabricated on a V-grooved GaAs/Si substrate by regrowth using metalorganic chemical vapor deposition. The dimension of the vertically-stacked patterned quantum wells was (20–25 nm)×(75–125 nm). The laser with the p+-GaAs internal current-confining layer has exhibited the cw low-threshold current as low as 16 mA at room-temperature. This result indicates that the small-volume of the active regions contributes to the reduction of the threshold current for the lasers on Si.
Photopleochroism of GaPxAs1-x Surface-Barrier Structures
Authors: Konnikov S. G. , Rud' V. Yu. , Rud' Yu. V. , Melebaev D. , Berkeliev A. , Serginov M. , Tilevov S.
Published: March 2014

The proposed work reported here constitutes the first investigation of the polarimetric effects in III-V surface-barrier structures of metal-semiconductor (Au-n-GaP
x
AS1-x
, Au-n-GaP) type, illuminated with linearly polarized radiation (LPR) at oblique incidence on the entrance plane (Au). As the angle θ increases the coefficient of photopleochroism increases as P∼θ2. The maximum azimutal photosensitivity of the Au-n-GaP
x
As1-x
(x=0.45–1.0) structures is \varPhiI=0.15–0.20 A/W deg at θ=80° (300 K).
Photorefractive Effect in CdGa2Se4
Authors: Mononobe Shuji , Horinaka Hiromichi , Wada Kenji , Yamamoto Nobuyuki , Cho Yoshio
Published: March 2014

We report the first observation of the photorefractive effect in a defect chalcopyrite semiconductor CdGa2Se4. At 633 nm wavelength, the photorefractive two-beam coupling gain was measured for 0.62 µm grating period with rotating the crystal around the nearly [110] axis for both the s-polarised signal and pump beams and the p-polarized beams. The maximum gain 0.88 cm-1 for the rotation angle was obtained when the grating wave vector was oriented to the [001] axis for the s-polarized beams.
Thin Film Cu2S–CdS and Cu2S–Cd1-xZnxS Solar Cells
Authors: Dzhafarov T. D. , Bairamov A. I. , Novrusov V. D. , Nadzhafov H. I. , Rzakuliev N. A. , Mamedov N. T.
Published: March 2014

Electrical, photoelectrical and degradation properties of thin film Cu2S–CdS and Cu2S–Cd1-x
Zn
x
S solar cells on the basis of CdS and Cd1-x
Zn
x
S (x=0.15) film prepared by spray pyrolysis and evaporation in quasiclosed volume were investigated. It was shown that the thin film solar cells produced by evapolation are high efficient (η=7%) and stable.
Lattice Dynamics and the Far Infrared Spectra of PrxLn1-xBa2Cu3O7-y (Ln=Lanthanide)
Authors: Onari Seinosuke , Nishikawa Kiyoshi , Ono Akihiko , Fukunaga Hirota , Makino Hisao , Matsuishi Kiyoto , Arai Toshihiro , Mori Tatsuo
Published: March 2014

Lattice dynamical calculations on high T
c superconductors and non superconductors Pr
x
Ln1-x
Ba2Cu3O7-y
(Ln=Y, Er, Ho, Dy, Gd, Sm, Nd) are studied using the shell model. Far infrared reflection spectra of Pr
x
Ln1-x
Ba2Cu3O7-y
are studied for various Pr concentration x. Carrier density of 4–6×1020 cm-3 is shown from the infrared optical measurement to be the critical carrier concentration for the appearance of the superconductivity for all Ln. “Barium mode” near 154 cm-1 has large oscillator strength for the systems studied here. The oscillator strength of the phonon band by the Kramers-Kronig analysis is found to depend strongly on the absolute value of the broad back ground reflection, and the origin of the anomalously large change of the oscillator strength of the “Barium mode” near 154 cm-1 is attributed to this effect.
Co2+ in Defect Chalcopyrite Solid Solutions and Valence Band Offest in Defect Chalcopyrite Solid Solutions
Authors: Park Hong-Lee , Lee Yang-Lae , Kim Jae-Eun , Park Hae-Yong , Choi Chi-Kyu , Kim Wha-Tek
Published: March 2014

The purpose of this presentation is to report the valence band offset assignment in Zn1-x
Cd
x
Ga2Se4/ZnGa2Se4, Zn1-x
Hg
x
Ga2Se4/ZnGa2Se4, Cd1-x
Hg
x
Ga2Se4/CdGa2Se4, HgGa2-x
In
x
Se4/HgGa2Se4 heterojunctions using transition metal energy level in the gap as a reference. We used the energy level of Co2+ in defect chalcopyrite solid solutions to evaluate the valence band offset. The composition dependent energy gaps E
g(x) are presented along with E
g
Co2+(x), i.e., energy gaps of cobalt doped solid solutions. The valence band offset is expressed as the difference in energy gap between pure and cobalt doped solid solutions.
Possible Site of Co2+ Ions in Zn1-xCdxGa2Se4 Crystals
Authors: Hwang Insun , Lee Nam-Young , Kim Hidong , Kim Jae-Eun , Park Hae Yong , Kim Hyung-Gon , Kim Chang-Dae , Kim Wha-Tek
Published: March 2014

Zn1-x
Cd
x
Ga2Se4 crystals and Co2+-doped ones with values between x=0.0 and x=1.0 at intervals of 0.2 were investigated by XRD and Raman spectroscopy in order to determine the possible site of Co2+ ions in these crystals. It seems from the changes of the lattice parameters and Raman shifts of these samples that Co2+ ions possibly locate at the site of Ga atoms. Since Co2+ ions will act as acceptors in this case, we can also discuss the valence band offset in Zn1-x
Cd
x
Ga2Se4/ZnGa2Se4 heterojunctions.
Growth Mechanisms and Diffusion in Multinary and Multilayer Chalcopyrite Thin Films
Authors: Klenk R. , Walter T. , Schmid D. , Schock H. W.
Published: March 2014

Multisource physical vapor deposition does not only provide the possibility to grow homogeneous multinary films but can also act as a tool for analyzing the growth process and for the interactions of different phases. The present level of knowledge about growth interfaces is reported. Different approaches for studying the growth of films are described in this contribution namely growth of films with excess Cu, CuInSe2/CuGaSe2 multilayers and growth of CuIn(Se, S)2 at different Cu/In ratios.
Calculation of Phonon Frequencies of Predicted CdGeSb2 Chalcopyrite Compound
Authors: Artús L. , Royo S.
Published: March 2014

CdGeSb2 belongs to the group of the predicted ternary chalcopyrite compounds. In the present work, the frequencies of its normal modes at zone center are calculated. A Valence Force Field model which had already been successfully used for other chalcopyrite compounds was applied. In order to determine the bond-stretching and the bond-bending parameters used in the model, the previously determined bondlength dependence of the force constants was used. Therefore, its phonon frequencies can be calculated only from its atomic masses and interatomic distances. The analysis of the results obtained shows that there is a close correspondence between the predicted phonons of this compound and the phonons of CdGeP2 and CdGeAs2 chalcopyrite compounds.
Temperature Dependence of First-Order Raman Scattering in CuGaS2
Authors: González J. , Guinet J. , Fontaine H. , Longueville W.
Published: March 2014

We have measured the temperature dependence of the first-order Raman scattering of CuGaS2 single crystals in the range 10–300 K. The frequency shift analysis shows that the purely anharmonic contribution to the shift is a constant, within experimental error, in the range 100–295 K. The values of (dω/dT)
v
are inversely related to the values of the mode Grüneisen parameter. We show that the model assuming decay of the Raman phonons into two acoustical phonons belonging to the same branch, first proposed by Klemens's, does not adequately represent the temperature dependence of the Raman line width.
Raman and Infrared Spectra of Misfit Layer Compounds MNbS3 (M=Sn, Pb, La, Ce)
Authors: Hangyo Masanori , Nishio Toshifumi , Nakashima Shin-ichi , Ohno Youichi , Terashima Taichi , Kojima Norimichi
Published: March 2014

Raman scattering and infrared reflection spectra of misfit layer compounds MNbS3 (M=Sn, Pb, La, Ce) have been measured to study the interlayer interaction and the charge transfer from the MS layer to the NbS2 layer. Analysis of the Raman spectra indicates that the interlayer interaction is considerably stronger for the La and Ce compounds than for the Sn and Pb compounds, which may be related to the difference in the amount of the charge transfer.
Preparation and Characterization of Cu(Al, Ga)(S, Se)2 Penternary Alloys
Authors: Ogawa Akihiro , Sudo Ryo , Gupta Akhlesh , Shirakata Sho , Chichibu Shigefusa , Matsumoto Satoru , Isomura Shigehiro
Published: March 2014

Photoreflectance (PR) and Photoluminescence (PL) measurements have been performed at 77 K on single crystals of CuAl
x
Ga1-x
(S0.5Se0.5)2 penternary alloys grown by the iodine chemical vapor transport method. The energies of excitons associated with uppermost valence bands have been obtained as a function of composition, and an approximately quadratic dependence has been found. Near-band-edge PL has been observed in the crystal with x≦0.77, and the PL has been discussed in terms of the free exciton.
Optical Propeties of Cd1-xCoxIn2Se4 Single Crystals
Authors: Choe Sung-Hyu , Park Bok-Nam , Yu Ki-Su , Oh Se-Jung , Park Hong-Lee , Kim Wha-Tek
Published: March 2014

Cd1-x
Co
x
In2Se4 (x=0.0, 0.01, 0.05, 0.10, 0.50) single crystals were grown by the vertical Bridgman technique. The grown single crystals have a pseudocubic structure. The optical energy gap of these single crystals has an indirect energy gap whereas its value is decreased with increases in composition x. The optical absorption peaks due to cobalt atoms are observed at each composition. It is suggested that the substituted cobalt atoms for cadmium atoms are located at T
d symmetry of the CdIn2Se4 host lattice as Co2+ ions by the static crystal field theory. These peaks can be attributed to the electronic transitions between the split electron energy levels of Co2+ ions.
Magnetic Circular Dichroism Spectra of Eu-Doped CaS and SrS Single Crystals
Authors: Kijima Satoru , Ohki Shigeharu , Sato Katsuaki , Kishio Koji
Published: March 2014

Spectra of magnetic circular dichroism (MCD) of absorption and photoluminescence in Eu-doped single crystals of CaS and SrS were measured at 20 K. Fine structure bands were observed in both MCD spectra of CaS:Eu, the peak positions being analyzed in terms of the phonon replica associated with zero phonon line (ZPL) of the f-d transition in Eu2+ ion. On the other hand, no fine structures could be observed in SrS:Eu. The MCD lineshape of the ZPL in CaS:Eu was successfully explained in terms of the electric dipole allowed transition between the 8S (4f7) ground muitiplet and the 8P (4f65d) excited muitiplet.
Single Crystals of CuAlS2 Doped with Rare-Earth Ions
Authors: Ohgoh Tsuyoshi , Kudo Yuki , Sato Katsuaki
Published: March 2014

Photoluminescence spectra have been studied in CuAlS2 single crystals doped with a series of rare-earth ions grown by the chemical vapor transport technique. Several sharp emissions originated from electronic transitions between the L-S coupling terms of 4f-shell originated multiplets have been observed for Tb3+, Tm3+ and Ho3+ ions in CuAlS2 host, whereas the spectra of Ce- and Sm-doped crystals showed no significant difference from the undoped crystals.
Defect Levels of AgGaS2 Single Crystals
Authors: Niwa Eiji , Mochizuki Katsumi , Masumoto Katashi
Published: March 2014

The defect levels of as-grown AgGaS2 single crystals with the energy depths of about 20, 50, 100, 170, 230, 390 and 700 meV from the edge of either valence band or conduction band were estimated from the temperature dependence of photoconductivity spectrum. The relations between those levels and the emission peaks in the photoluminescence spectrum were discussed and a possible band diagram was made.
Blue-Band Emission of LiInS2 Single Crystals Grown by the Indium Solution Method
Authors: Kuriyama K. , Kato Tomoharu
Published: March 2014

It is demonstrated that the undoped and Zn-doped LiInS2 single crystals are grown using indium solution technique. The optimum weight ratio between the starting materials (LiIn and S) and In solvent was found to be 1:3. The photoluminescence (PL) emissions in the blue-band region were observed for undoped and Zn-doped crystals. It is proposed that in addition to the donor-valence-band transitions related to the native defects (Vs and InLi) in undoped crystals, the PL emission of Zn-doped crystal consists of a multiple transition related to the intentionally introduced impurity, ZnLi, which act as a donor.
Preparation and Characterizations of CuInxGa1-xSe2 Thin Films Crystallized by Annealing
Authors: Yamaguchi Toshiyuki , Suzuki Masayoshi , Yoshida Akira
Published: March 2014

A new approach for fabrication of polycrystalline CuIn
x
Ga1-x
Se2 (0≤x≤1) thin films by annealing of evaporated Cu–In–Ga–Se alloy films has been presented. X-ray diffraction analyses showed that these thin films had chalcopyrite structure and the lattice parameters were varied linearly with x in the thin films. The thin films had optical absorption coefficients in the high 104 cm-1 range and the band gaps were changed from 0.99 to 1.68 eV with decreasing x. The variation of band gaps yielded the bowing parameter of 0.156 eV.
Optical and Electrical Characterization of CuGaS2 Grown by Vapor Phase Epitaxy
Authors: Morohashi Makoto , Ando Yoshihide , Tsuboi Nozomu , Terasako Tomoaki , Iida Seishi , Okamoto Shoichi
Published: March 2014

Investigations were made on band-edge-region photoluminescence and the electric resistivity of CuGaS2 epitaxial films on GaAs and GaP substrates, which were prepared by vapor phase epitaxy using metal chlorides and H2S gas. The similar temperature dependence was observed on the resistivity and the intensity of 2.40 eV emission, giving nearly the same activation energy of about 0.05 eV. This value suggests the existence of an acceptor shallower than the acceptor of effective mass approximation. A proposed candidate of this shallow acceptor is an interstitial chlorine atom coming from source materials.
The Green Broad Band Photoluminescence in Sulfur Annealed CuGaS2 Single Crystals
Authors: Kobayashi Satoshi , Sagawa Toru , Kimura Takayuki , Kaneko Futao
Published: March 2014

Some properties of the green broad band photoluminescence observed near 516 nm at low temperatures on CuGaS2 are described. It is concluded that the band consists of two bands (516 nm and 513 nm) with the different temperature dependence of the emission intensity. The 516 nm band is predominant at low temperatures and due to the donor-acceptor pair transition, while the 513 nm band is predominant at high temperatures and not due to the donor-acceptor pair transition.
Photoconductivity and Luminescence of CuGaSe2 Single Crystals
Authors: Cantser O. C. , Kulyuk L L. , Shemyakova T. D. , Siminel A. V. , Tezlevan V. E.
Published: March 2014

In this paper the photoconductivity and photoluminescence spectra as a function of temperature (90–300 K) of CuGaSe2 single crystals are discussed. The photoconductivity spectra peculiarities (90 K), have been explained by the interband transitions and by trasitions from splitting levels of valence band and excited 3d level of copper to the top of the valence band. A peculiarities at 300 K (1.28 eV and 1.55 eV) can be connected with a deep acceptor centers. A peculiarity at 1.38 eV can be ascribed to a deep donor center due to iodine impurity. It has been shown that the photoluminescence spectra are greatly influenced by the near-surface layer of the CuGaSe2 single crystals.
Photoelectrical Properties of CdZnSe2
Authors: Lal Manohar , Goyal Navdeep , Grover A. K. , Vohra Anil
Published: March 2014

An investigation of photoconductivity in films of CdZnSe2 prepared by solution growth technique is reported. The measurements were carried out at different temperatures and excitation intensities. Photoconductivity is found to increase exponentially in the temperature range (303–343 K). The value of I
ph/I
d is found to decrease with an increase in temperature. In order to investigate the nature of decay of photocurrent, transient photoconductivity measurements have also been carried out at various temperatures and excitation intensities. The results are well explained by recombination of excess D° states in localized-localized recombination.
Nonlinear Spectroscopy of Deep Levels in Ferroelectric SbSI Crystals
Authors: Gavryushin V. , Račlukaitis G. , Kazlauskas A. , Juodžbalis D. , Puzonas G.
Published: March 2014

Local lattice defects in SbSI crystals and the optical transitions associated with defects, which drastically change under ferroelectric phase transformation, are investigated by means of the spectroscopy of photo-induced absorption (PIA). The thermal changes in the spectra are caused by the replacement of the predominating type of optical modulation of deep level occupation: by direct optical ionization of the center or by capture of non-equilibrium free carriers generated by two-photon absorption of laser radiation. The results are explained by considerable modifications in the band structure under phase transition. It is accompanied by the replacement of impurity absorption from one point of Brillouin zone to the other, thus reflecting a splitting of the valence band. These processes are confirmed by the band-structure calculations for SbSI.
A Self-Energy Correction to LDA Gaps of Ternary Semiconductors
Authors: Pascale T. M. de , Meloni F. , Serra M.
Published: March 2014

The calculated energy gaps of insulators are always underestimated in the Local Density Approximation (LDA) to the Density Functional Theory (DFT). The problem makes difficult an exact assignment of the optical intraband transitions. In this paper we apply a method recently proposed and based on a dielectric model scheme to some ternary semiconductors like chalcopyrites, spinels and layer phases. The results account for the right order of magnitude of their minimum gap and make comparable the complete energy dispersion including the excited states.
Actual Carrier Mobility Determination of GaInAsSb/InAs Grown by Liquid Phase Epitaxy
Authors: Yamaguchi Tomuo , Suzuki Isao , Kan Gong , Aoyama Mitsuru , Kumagawa Masashi
Published: March 2014

A theory for the effective mobility and the density of carriers of a double layer is given and compared with an old theory established by Petritz [Phys. Rev. 110 (1958) 1254]. Validity of the present theory is confirmed by an experiment using an epitaxial layer of Gd-doped GaInAsSb layer grown on an InAs substrate by Liquid Phase Epitaxial (LPE) method.
Crystal Growth and Transport Properties of Ba-Doped Bi(Pb)2Sr2Ca2Cu3Oy Compounds
Authors: Akinaga Masahiro
Published: March 2014

Ba-doped Bi(Pb)2Sr2Ca2Cu3O
y
compounds with several different Ba content have been prepared by sintering method, and their transport properties in normal state and superconducting mixed state were measured in detail. The results of the resistance measurements showed a slight increase of transition temperature by Ba doping. A limited small amount of Ba atom was contained into the layered structure of 2223 phase in spite of large nominal addition. With increasing nominal Ba content, Ba-rich impurity phase appears but the 2223 layered crystal still grows more clearly and in larger scale. The growth of the Ba-rich impurity phase seems to assist the growing of the 2223 layered phase finely.
Influence of Lattice Mismatch on the Electrical and Structural Properties of HgCdTe Epilayers
Authors: Sugiura Lisa , Shigenaka Keitaro , Nakata Fumio , Hirahara Keijiro
Published: March 2014

The influence of lattice mismatch on the electrical and structural properties of HgCdTe epilayers grown on CdZnTe substrates has been investigated. A slight lattice mismatch of the order of less than ±0.1% between the epilayer and the substrate brings about a conductivity-type conversion of HgCdTe layers, which is related to the presence of misfit dislocations. It is considered that the conductivity-type conversion is caused by diffusion of impurities from the substrate to the epilayer due to the high interface dislocation density. This work emphasizes the importance of minimizing the interactions between the epilayer and its substrate by the precise lattice-matching.
Synthesis and Characterization of SrxNbO3 (x≥0.5) of a Perovskite Related Structure
Authors: Isawa Kazuyuki , Sugiyama Jun , Yamauchi H.
Published: March 2014

Polycrystalline samples of Sr
x
NbO3-δ with x≥0.5 were successfully synthesized by a solid state reaction technique using TiO as reducing agent. Powder X-ray diffraction analysis revealed that the samples with 0.75<x≤0.90 were single phase of the cubic perovskite structure. For the single phase samples, the oxygen content and the average oxidation state of niobium in the samples were determined by an IR method and thermogravimetrlc (TG) measurements. It was found that the oxygen content was nearly stoichiometric (i.e. δ∼0), but the TG measurements tended to give somewhat higher values for the oxygen content. According to TEM images, there was neither short-nor long-range ordering of vacancies in the Sr site.
Electrochemical, Room Temperature Reduction, Oxidation and Microscopic Patterning of Multinary Cuprate Superconductors
Authors: Scolnik Yosef , Rappaport Michael , Cahen David
Published: March 2014

YBa2Cu3O7 (1237) was reduced and reoxidized at room temperature (RT), by using wet electrochemistry to extract, or solid state electrochemistry to re-insert oxygen. With thin films this led to homogeneous products, as judged by X ray diffraction and temperature dependence of electrical resistivity. Because reduction leads to loss of superconductivity and re-oxidation restores it, this method allows room temperature control over superconducting properties of (parts of) films and, thus, can be used for patterning of (1237) thin films. We showed this by preparing SNS-like structures by this method. The method affords control not only over bulk properties, but also over the quality of the intergranular contact, possibly via control of oxygen concentration and ordering in the outermost layers of grains (in films and pellets). The results imply rapid, field-assisted, oxygen motion and this was confirmed by independent measurements.
Crystal Growth and Electronic Structure of Metal Substituted BaBiO3
Authors: Shiozaki Ikuyo , Ishii Hiroyoshi
Published: March 2014

Single crystals of BaBiO3 and BaBi1-x
Mo
x
O3 were grown by slow cooling of the molten mixture. The quality of the crystal was improved by addition of the excess BaCO3 of 20% to the mixture of starting materials with the cationic stoichiometry. Golden brown crystals grew, whose sizes ranged from 3×3×2 to 10×10×5 mm3. Quantitative analysis of BaBiO3 showed that the atomic ratios, Ba/Bi, ranged in 0.92–1.14. The oxygen stoichiometry was estimated as 2.83±0.05. The mass density was more than 96% of the calculated one. The ceramic compounds, Ba2BiInO6 and Ba2BiLaO6 were synthesized, too. It was found from the powder X-ray diffraction analysis, that the volume of Ba2BiInO6 is reduced by 5.3% of that of BaBiO3. The band structures of the compounds were examined by XPS. In Ba2BiInO6 4d level appeared below the valence band, while it was not observed in BaBi0.92Mo0.08O3.
Liquid Phase Epitaxy of Bi2Sr2CaCu2O8+x Superconducting Films by the Tipping Method
Authors: Huang Yu , Huang Mei-Hwei
Published: March 2014

Epitaxial film of Bi2Sr2CaCu2O8+x
was successfully grown onto the (001)-oriented NdGaO3 substrate by tipping liquid phase epitaxial method using a Bi-rich solution as self-flux. The resistivity curve is metallic, with 6 K wide transition and zero resistivity at 85 K.
Superconductivity of ZrRuP
Authors: Shirotani Ichimin , Ichihashi Nobuharu , Nozawa Kiyokazu , Kinoshita Minoru , Yagi Takehiko , Suzuki Kazuya , Enoki Toshiaki
Published: March 2014

Hexagonal ZrRuP, HfRuP and Hf0.5Zr0.5RuP and orthorhombic ZrRuP which show an interesting superconductivity have been prepared at high temperatures and high pressures. The electrical resistivity and the dc magnetic susceptibility of these phosphides have been studied at low temperatures. The superconducting transition temperatures of the phosphides with the hexagonal structure were much higher than those with the orthorhombic structure.
Preparation of As-Deposited 80 K-Phase Bi–Sr–Ca–Cu–O Films by RF Magnetron Sputtering
Authors: Kishida Satoru , Tokutaka Heizo , Kinoshita Hideki , Fujimura Kikuo
Published: March 2014

We prepared the as-deposited 80 K-phase Bi–Sr–Ca–Cu–O (BSCCO) films using the rf magnetron sputtering method with a single target. When the substrates were set at the position parallel to the target, the as-deposited 80 K-phase BSCCO films with the zero-resistance temperature of 65 K were prepared at the substrate temperatures from 630 to 650°C under the total gas pressure of 200 mTorr, where the ratio of oxygen to total gas pressure was from 75 to 100%. The regions of substrate temperature and total gas pressure for obtaining the 80 K-phase BSCCO film were extended by setting the substrate at the position perpendicular to the target.
Misfit Layer Compounds Based on Double Layers MX and Sandwiches TX2 (M=Sn, Pb, Sb, Bi, Ln; T=Ti, V, Cr, Nb, Ta; X=S, Se)
Authors: Wiegers G. A.
Published: March 2014

Misfit layer compounds have a composite structure with two interpenetrating subsystems, an MX and an TX2 or (TX2)2 subsystem. Several structure types occur, the main difference coming from the different type of coordination of transition metal T by X atoms of the TX2 sandwiches. All structures show the presence of a common (b
*, c
*) plane in reciprocal space which comes from space fitting and from the interaction between the two subsystems. A classification of structures can be given based on the symmetries of the two subsystems. Since the diffraction pattern of the composite crystal is given by four reciprocal vectors, the symmetry can be described in (3+1)D superspace. The composition, which is generally non-stoichiometric, is determined by the ratio of the unit cell volumes of the two sublattices; the temperature dependence of the composition is governed by the thermal expansion. The physical properties are discussed in relation with chemical bonding. The electrical resistivity for compounds with NbX2, TaX2 or TiX2 sandwiches is metallic, the inplane resistivity being about 10-4 smaller than the resistivity along c. Hall effect and thermopower seem to indicate that the conduction takes place within the sandwich layers. For compounds with M=Sn, Pb, Sb, Bi, the intralayer M-X distances are shorter than the interlayer distances indicating a weak interaction; Hall effect and photoelectron spectroscopy indicate no or hardly any electron transfer from MX to TX2 for such compounds. The interaction between layers LnX and TX2 is strong; intra- and interlayer Ln-X distances are about equal and correspond to those for Ln3+; the magnetic properties also point to Ln3+. Hall effect and thermopower are in a greement with electron transfer and conduction in the TX2 sandwiches. Photoelectron spectroscopy confirms that Ln is trivalent; indications for charge transfer are less clear. Reflection spectra in the range 2000–20,000 cm-1 are in agreement with charge transfer.
Influence of Ga Concentration on the Ordering Process of GaxIn1-xP Grown on GaAs
Authors: Eyal A. , Beserman R. , Wei S. H. , Zunger Alex , Maayan E. , Kreinin O. , Salzman J. , Westphalen R. , Heime K.
Published: March 2014

We study the ordering process of Ga
x
In1-x
P/GaAs, for lattice matched and non-lattice matched samples in the Ga concentration range 0.51<x<0.57. The valence band splitting and the band gap reduction are calculated for partially ordered samples as a function of the Ga concentration and of the long range order (LRO) parameter. Using polarized photoluminescence, we compare the effect of growth temperature and that of Ga concentration on the LRO parameter. The degree of ordering depends strongly on growth temperature, in the range 600°C to 725°C. On the other hand, the change in alloy composition has a minor effect.
Molecular Approach to Surface Control of Chalcogenide Semiconductors
Authors: Moons Ellen , Bruening Merlin , Burstein Larisa , Libman Jacqueline , Shanzer Abraham , Cahen David
Published: March 2014

The interaction between a chalcogenide semiconductor surface and a specific chelating ligand was studied by a number of complementary spectroscopic methods (UV/VIS, FTIR, XPS). FTIR suggests that the chelating ligand (diphenyl hydroxamic acid) complexes an In3+ ion in CuInSe2, and a Cd2+ ion in CdTe, accompanied by the loss of a proton. Contact potential measurements showed that the adsorbed ligand changes the semiconductor electron affinity without significantly influencing the band bending. On the basis of these and other results, we suggest that the molecular dipole of the chelating ligand is responsible for the change in surface potential. Because this dipole can be modified without changing the ligand's binding group, this finding opens the way to control surface potential by varying the dipole moment of the adsorbed ligand without changing the binding functional group.
Conversion of GaAs Layer Grown on GaP Substrate to GaAsP in LPE System
Authors: Udono Haruhiko , Katsuno Hironobu , Tanaka Akira , Sukegawa Tokuzo
Published: March 2014

A new fabrication technique of GaAsP layers with a desired composition on a GaP substrate was developed. A GaAs layer grown on a GaP substrate by step cooling was brought into contact with Ga–As–P saturated solution and kept at 795°C. This annealing process resulted the compositional conversion of the GaAs layer to GaAsP. The composition of the conversion layer could be controlled by adjusting the composition of the Ga–As–P solution. Fairly good GaAsP layers were grown on the conversion layer by a consecutive slow cooling after the conversion process.
Homogeneous GaInSb Bulk Alloy Pulling by Solute-Feeding Czochralski Method
Authors: Watanabe Akiyoshi , Tanaka Akira , Sukegawa Tokuzo
Published: March 2014

Pulling technique of bulk alloys with a desired and uniform composition was developed. Stable CZ-mode growth from GaSb-InSb pseudo-binary solution fed with GaSb solute was realized by the use of a two-chamber (growth and source) crucible. The alloy with 3 mol% InSb was pulled at a constant temperature of 691°C. Subsequently, using this grown alloy as the second seed, the alloy with 5 mol% InSb could be pulled successfully at 672°C.
Optical Study of Localized Exciton States in CdTe/ZnTe Superlattices
Authors: Okamoto Hiroshi , Suzuki Kyoichi , Tsuzuki Ken , Takahashi Masaaki , Oka Yasuo
Published: March 2014

Stokes shift (S) and linewidth (W
em) of exciton luminescence were studied as a function of the well layer thickness in the CdTe/ZnTe superlattice (SL) by the measurements of photoluminescence and photoluminescence excitation spectra. The interface roughness in the SLs was evaluated about ±1 monolayer by taking account of the localized nature of the exciton. The relation S=0.75W
em has been obtained, which could be interpreted by the random distribution of the interface fluctuations.
TlMeX2 Ternary Compounds: Phase Transitions: Non-Linear Low-Frequency Lattice Modes in TlMeX2 Layered Crystals
Authors: Mamedov N. T. , Abdullaeva S. G. , Gadjiev B. R.
Published: March 2014

Possibility of the phase transition accompanied by the modes, different from the well-known soft mode observed in majority of crystals, is pointed out. An evidence for existence of such a mode is also given on the basis of studying the temperature behaviour of quadrupole perturbed nuclear magnetic resonance frequency of gallium nuclei.
Physics and Applications of Metallic Arsenic Clusters in GaAs Based Layer Structures
Authors: Melloch M. R. , Otsuka N. , Harmon E. S. , Nolte D. D. , Woodall J. M. , McInturff D. T.
Published: March 2014

A semimetal/semiconductor composite material is demonstrated consisting of semimetallic clusters of As in high-quality arsenide semiconducting matrices. These composites exhibit several interesting properties including high-resistivity, appreciable optical absorption below the bandgap of the semiconducting matrix material, a large electro-optic effect, and very short carrier lifetimes.
Nonlinear and Photoinduced Optical Phenomena in Multinary Chalcogenide Glasses
Authors: Andriesh A. M.
Published: March 2014

The results of the investigation of the photoinduced absorption in fibers of different multinary glasses As–S–Se, As–Ge–Se, As2S3 are described in terms of the model with carriers multiple trapping in localized states. The nonlinear optical absorption in the chalcogenide was observed. The phenomenon is explained taking into account the processes of nonequilibrium phonons and strong electron-phonon interaction in noncrystalline materials.
New Multinary Layered Chalcogenides with Octahedral and Tetrahedral Cation Coordination
Authors: Moldovyan N. A. , Pyshnaya N. B. , Radautsan S. I.
Published: March 2014

Peculiarities of structure formation of layered chalcogenides with mixed tetrahedral and octahedral cation coodination are considered. The criterion for purposive search of new layered compounds was proposed. New layered compounds as Cu(Ag)Ga2.5In2.5S8, Mg0.5Ga2InS5, CuIn5S3Se5 and others were obtained and studied.
Compensated Electrical Properties of CuInSe2 Single Crystals
Authors: Nomura Shigetaka , Itoh Jun , Takizawa Takeo
Published: March 2014

Electrical properties of stoichiometry-controlled single crystals of CuInSe2 are investigated by the Hall effect measurement over the temperature range of 20 to 300 K. Overshoot characteristics have been observed in the temperature dependence of the Hall coefficient for all p-type crystals. The compensating donor density is shown to be a dominant factor for the Hall overshoot rather than the acceptor density. If we assume a relation that µn/µp=Const.T
-η with η around 1.5, the Hall overshoot is well explained.
Controls on segmentation and morphology along the back‐arc Eastern Lau Spreading Center and Valu Fa Ridge
Authors: Sleeper Jonathan D. , Martinez Fernando
Published: March 2014

Back‐arc spreading centers increasingly depart from mid‐ocean ridge (MOR) characteristics with proximity to the arc volcanic front. The close association of these departures with slab‐derived materials in erupted lavas suggests that subduction‐related chemical effects are their primary cause. The Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) are type examples of this process. Together they constitute a first‐order spreading center in the Lau back‐arc basin that progressively converges on the Tofua arc volcanic front from north to south. Here we use ship multibeam and deep‐towed side‐scan sonar data to examine variations in axial morphology and volcanism at the second‐ and third‐order segment scale along these ridges and develop a model for the processes that control them. Closest to the arc, VFR, and the southern segment of the ELSC shoal toward second‐order segment ends, in contrast to MORs. Northward and beyond ~70 km from the arc, the axis becomes abruptly deeper and flatter and no longer shoals toward second‐order segment ends. At VFR, along‐axis topographic highs correlate with the location of arc volcanoes along slab flow lines. These correlations are weaker along the southernmost ELSC segment and absent along ELSC segments farther north. The observations show a modulation of back‐arc segmentation with arc proximity that rapidly diminishes with distance. They support a model of the mantle wedge with a strongly hydrous domain within ~70 km of the arc within which the arc and ridge interact and a much less hydrous domain farther from the arc without evident arc‐ridge interactions.
Creation of Bifunctional Materials: Improve Electron‐Transporting Ability of Light Emitters Based on AIE‐Active 2,3,4,5‐Tetraphenylsiloles
Authors: Chen Long , Jiang Yibin , Nie Han , Lu Ping , Sung Herman H. Y. , Williams Ian D. , Kwok Hoi Sing , Huang Fei , Qin Anjun , Zhao Zujin , Tang Ben Zhong
Published: March 2014

2,3,4,5‐Tetraphenylsiloles are excellent solid‐state light emitters featured aggregation‐induced emission (AIE) characteristics, but those that can efficiently function as both light‐emitting and electron‐transporting layers in one organic light‐emitting diode (OLED) are much rare. To address this issue, herein, three tailored n‐type light emitters comprised of 2,3,4,5‐tetraphenylsilole and dimesitylboryl functional groups are designed and synthesized. The new siloles are fully characterized by standard spectroscopic and crystallographic methods with satisfactory results. Their thermal stabilities, electronic structures, photophysical properties, electrochemical behaviors and applications in OLEDs are investigated. These new siloles exhibit AIE characteristics with high emission efficiencies in solid films, and possess lower LUMO energy levels than their parents, 2,3,4,5‐tetraphenylsiloles. The double‐layer OLEDs [ITO/NPB (60 nm)/silole (60 nm)/LiF (1 nm)/Al (100 nm)] fabricated by adopting the new siloles as both light emitter and electron transporter afford excellent performances, with high electroluminescence efficiencies up to 13.9 cd A–1, 4.35% and 11.6 lm W–1, which are increased greatly relative to those attained from the triple‐layer devices with an additional electron‐transporting layer. These results demonstrate effective access to n‐type solid‐state emissive materials with practical utility.
The Optical Fiber Tip: An Inherently Light‐Coupled Microscopic Platform for Micro‐ and Nanotechnologies
Authors: Kostovski Gorgi , Stoddart Paul R. , Mitchell Arnan
Published: March 2014

The flat tip of an optical fiber is a unique and unconventional platform for micro and nanotechnologies. The small cross‐section and large aspect ratio of the fiber provide an inherently light‐coupled substrate that is uniquely suited to remote, in vivo and in situ applications. However, these same characteristics challenge established fabrication technologies, which are best suited to large planar substrates. This review presents a broad overview of strategies for patterning the flat tip of an optical fiber. Techniques discussed include self‐assembly, numerous lithographies, through‐fiber patterning, hybrid techniques, and strategies for mass manufacture, while the diverse applications are discussed in context throughout.
Phase‐Transfer‐Catalyzed Asymmetric α‐Arylation of α‐Amino Acid Derivatives
Authors: Shirakawa Seiji , Yamamoto Kenichiro , Tokuda Takashi , Maruoka Keiji
Published: March 2014

Highly enantioselective α‐arylation of α‐amino acid derivatives via nucleophilic aromatic substitution (SNAr) was achieved under phase‐transfer conditions. Various kinds of α‐amino acids and aryl triflates containing a nitro group can be tolerated in this reaction to give α,α‐disubstituted α‐amino acids in good to high enantioselectivity. This reaction demonstrates a valuable method for the catalytic asymmetric synthesis of α,α‐disubstituted α‐amino acids containing an aromatic substituent.
Experimental investigation in rats to identify the cause of sudden death during bathing in Japan
Authors: Suzuki Masaru , Hori Shingo
Published: March 2014

Aim

Approximately 14,000 cases of sudden death during bathing are reported annually in Japan. The cause of the deaths is still unclear. Because Japanese‐style bathing is characterized by whole‐body bathing in high temperature water (41–45°C), we hypothesized that heat exposure causes sudden death as a result of hyperthermia.

Methods

The aim was to clarify the relationship between heat exposure and mortality in an animal experiment. In the experiment, 44 male Wistar rats weighing 180–255 g were anesthetized with sodium pentobarbital, and their body temperature was measured with a thermometer inserted into the esophagus. The animals were immersed up to their shoulder in 40–45°C water until respiratory arrest occurred or until they awoke from the anesthesia.

Results

All animals immersed in water heated to ≥41°C died, whereas all animals immersed in 40°C water awakened from the anesthetic. The mean interval between the start of immersion and respiratory arrest in 41°C, 42°C, 43°C, 44°C, and 45°C water was 105 min, 54 min, 34 min, 27 min, and 22 min, respectively. Regression analysis revealed a significant relationship between the interval and water temperature (r2 = 0.96, P < 0.01), and a Cox proportional hazard analysis revealed that water temperature was a significant predictor (adjusted odds ratio, 23.9; 95% confidence interval, 7.4–77.2). The body temperature of the animals that died during hot water immersion was above 41°C (median, 42.9°C).

Conclusions

Water temperature was correlated with the interval between the start of immersion and respiratory arrest. The results suggest that hyperthermia contributes to the cause of sudden death during hot water bathing.
Usefulness of initial diagnostic tests carried out in the emergency department for blunt trauma
Authors: Ikegami Yukihiro , Suzuki Tsuyoshi , Nemoto Chiaki , Tsukada Yasuhiko , Tase Choichiro
Published: March 2014

Aim

To evaluate the usefulness of the initial diagnostic tests carried out in blunt trauma patients in our emergency department.

Methods

Blunt trauma patients admitted between October 2009 and October 2011 were retrospectively reviewed. A scoring system was developed (0 to 28 points) to differentiate between potential major trauma patients and physiologically stable patients. Patients were classified into three groups: Group I (minor trauma), revised trauma score normal and our score 0–14; Group II (potential major trauma), revised trauma score normal and our score 15–28; Group III (major trauma), revised trauma score low. The proportions of patients with positive initial diagnostic test results (blood tests, X‐rays, and computed tomography) were determined in each group.

Results

The study included 1,291 patients (Group I, 1,019; Group II, 85; Group III, 187). Blood tests and X‐rays were carried out frequently in all groups, but positive results were infrequent in Group I. Comparisons using Pearson's χ2‐test showed significant differences in the proportions of patients with positive blood test, X‐ray, and computed tomography results among the three groups. The proportions of patients with positive blood test and chest X‐ray results were significantly lower in Group II than in Group III, but there were no significant differences in the proportions of patients with other positive results between these two groups.

Conclusions

In physiologically stable blunt trauma patients, diagnostic tests should be selected only after careful patient evaluation. To achieve this, standardized criteria for the identification of minor trauma patients should be established.