bluuebunny/crossref_metadata_2025 huggingface dataset:
EXAFS Study of the Local Structure of Lanthanoid(III) Bromanilate Complexes
Authors: Sudoh Susumu , Miyanaga Takafumi
Published: March 2014

The local structure of lanthanoid(III) complexes such as Ln2(C6O4X2)3 · kH2O ; (X=Cl,Br,H), are studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. The curve fitting procedure was performed by assuming a single shell model for parameterization. The distance between the lanthanoid(III) ions and a coordinated oxygen was determined. The coordination numbers of lanthanoid(III) complexes were also obtained from the amplitude of the EXAFS signal relative to the standard compound of Ln(thd)3.
XANES and EXAFS Study in (R1, R2-DCNQI)2Cu
Authors: Oshima Kokichi , Doi Takashi , Maruyama Hiroshi , Maeda Hironobu , Yamazaki Hitoshi , Kato Reìzo , Kobayashi Akiko , Naito Toshio , Kobayashi Hayao
Published: March 2014

XANES and EXAFS measurements at Cu K-edge are reported for (R1,R2-DCNQI)2Cu. The mixed valence state of Cu proposed in this compound has been confirmed by the XANES study. The systematic XANES and EXAFS studies have revealed differences in the spectra between two groups in this compound (Group I is metallic down to low temperatures, and Group II shows a metal-insulator transition). The local structural change during the metal-insulator transition in the Group II compound has been confirmed using EXAFS analysis. The clear difference in XANES spectra between two groups has been attributed to the difference in the valence states.
The Chemical Shift of Copper(II) Ion by XANES Spectrometry
Authors: Wakita Hisanobu , Yamaguchi Toshio , Yoshida Nobuo , Fujiwara Manabu
Published: March 2014

The XANES spectra of copper(II) ions in solid state and in solution of the square-planar copper(II) complexes with tetraaza macrocycles were measured. The peaks in the measured XANES spectra shifted to lower energy side with increasing the electron density of central copper(II) ions. The clear chemical shift obtained by this XANES study is evaluated by a molecular orbital calculation, and leads to a new concept of π-back donation between the copper(II) complexes and counter anion in aqueous solution.
The Future of XAFS
Authors: Stern Edward A.
Published: March 2014

The ultimate information content of XAFS is discussed. The practical limits for obtaining this information are indicated. The most general case is considered where nothing is known about the structure and there is no orientation dependence of the XAFS with respect to the sample. For close packed structures it ultimately appears possible to obtain the two and perhaps some of the three particle correlation distribution functions between the center atom and the its first neighbors; two particle correlation distribution functions between the center atom and its second nearest neighbors and possibly some of the three particle correlation distribution functions between the center atom and its first and second nearest neighbor atoms. By the fourth neighboring atoms it appears that only the two particle correlation distribution function with the center atom is feasible. Beyond that the information content in XAFS is overwhelmed by the large number of multiple scattering paths contributing and it does not appear possible to obtain even the two particle distribution functions. For open structures it appears to be possible to obtain the two particle correlation distribution function between the center atom and its first three neighboring shells of atoms and perhaps some three particle correlations. When some information about the structure is known, or in special situations, it will be possible to obtain restricted information beyond these limits. The more brilliant future x-ray sources together with computing advances will make feasible the combining of XAFS with other techniques such as microscopy and tomography to produce two or three dimensional imaging of the XAFS spectrum with submicron resolution. Time resolution of XAFS measurements in the nanosecond range appears feasible The time resolution and the imaging will require automating the analysis of data to handle the overwhelming data content of such measurements. XAFS information will be utilized in many more phenomena than presently. Hints of the possibilities are seen in the fine structure of anomalous diffraction. Other future phenomena to be exploited are x-ray Raman scattering and its combination with diffraction, fine structure in electron energy loss and its combination with diffraction. The polarization of x-rays, both plane and circular, will be more intensely exploited, especially when XAFS is combined with diffraction, etc., because richer orientation, spin, and site dependences exist. The most exciting future developments may be awaiting the creative genius of the future scientific generation and not foreseen here.
Magnetic Absorption of Hard X-rays: New Aspects
Authors: Schütz Gisela , Fischer Peter , Stähler Silke , Knülle Matthias , Attenkofer Klaus
Published: March 2014

The study of magnetic XANES of circularly polarized hard x-rays at the K-edges of 3d- and at the L-edges in 4f- and 5d-elements in ferro(i)magnetic materials is a powerful method to study in an element-selective manner magnetic aspects of the electronic structure of solids. It is demonstrated on the basis of simplified single-particle band-structure pictures that for the 5d-elements polarized by 3d- neighbors, information on the local spin and orbital moments can be directly deduced from the magnetic L
2,3-spectra. Although the interpretation of the corresponding data of the rare earth is much more complicated interesting insights in the variation of their magnetic moment in different chemical environments and the binding character are possible as shown for Tb/Fe multilayered sample. The first observation of temperature-dependent changes of the magnetic absorption profile in invar alloys in comparison with theoretical calculations probe the applicability of magnetic K-edge spectroscopy on spin-fluctuating systems.
Simulation Study of Off-Center Shifts in Perovskite Systems
Authors: Joo Minsoo , Sayers Dale
Published: March 2014

An orientational order-disorder phase transition in perovskites has been studied by simulation using the FEFF-5 ab initio program. Off-center shifts of the central atoms toward the <100> directions in perovskite systems have been modeled for three different phases: (i) totally disordered, (ii) partially ordered, and (iii) totally ordered structures. XAFS spectra have been simulated as a function of temperature from these modeled structures. The relative Debye-Waller factors extracted from the simulated XAFS spectra have been quantitatively analyzed using the Einstein model and a single-shell approximation.
Chloride Multi-Source Epitaxial Growth of CuGaS2 and CuGaSe2
Authors: Matsumoto Takashi , Miyaji Yoshisuke , Kiuchi Kenji , Kato Takamasa
Published: March 2014

A novel epitaxial growth technique–chloride multisource epitaxial growth–for ternary compounds is described. Beams of the source vapors, CuCl, Ga and S (Se), are supplied into a high-purity nitrogen or hydrogen atmosphere of 10-4 Torr. The c-axis epitaxial growths of CuGaS2 and CuGaSe2 are attained on GaAs (100) substrates at 600–620°C. The effects of the CuCl/Ga supply ratio on the layer growth are examined. The epitaxial layers are strained compressively along the c-axis by the thermal expansion mismatch between the grown layer and the substrate.
Heteroepitaxial Growth of Chalcopyrite-type CuAlSe2 Compound Semiconductor by Molecular Beam Epitaxy
Authors: Kimoto Kazuhiko , Mochizuki Katsumi , Masumoto Katashi
Published: March 2014

The heteroepitaxial growth of chalcopyrite-type CuAlSe2 has been performed on GaAs (100) or CaF2 (111) substrates by molecular beam epitaxy. In this study, the film properties which depend on the growth conditions such as the beam flux ratio and the substrate temperature were examined. The epitaxial films of CuAlSe2 were obtained under the following conditions: the substrate temperature was 600°C and the beam flux ratio of Cu to Al was about 0.3 on both GaAs and CaF2 substrate.
Growth and Characterization of CuAlSe2 Crystals
Authors: Mochizuki Katsumi , Niwa Eiji , Kimoto Kazuhiko
Published: March 2014

CuAlSe2 crystals were grown by two methods. The one is melt growth by the Bridgman method and the other is chemical vapor transport using iodine as a transport agent. The basic characteristics of the grown crystals were examined. Lattice constants of a and c axes were exactly determined as 5.595 and 10.932 Å, respectively. In photoluminescence (PL) spectra at 4.2 K, an intense blue peak at 2.639 eV in near band-edge region and a weak orange band at 2.0 eV were observed for melt grown crystals, but only the orange band was found for vapor grown crystals. It was known that the blue emission is due to the radiative recombination of donor-acceptor pairs. The color of the crystals grown from the melt changes from yellow to black after exposing them to air for 1 week and this might be due to the oxidation of active (maybe unreacted) Cu and Al on the surface by forming CuO and Al2O3. Similar color change was not observed for vapor-grown crystals.
Single-Crystal X-Ray Diffraction Study on Structural Change of AgGaS2 with Increasing Pressure
Authors: Ishizawa Nobuo , Kitahara Hiromi , Komori Takashi , Noda Yasutoshi , Marumo Fumiyuki
Published: March 2014

Single-crystal X-ray diffraction study under high pressures has been carried out on silver thiogallate, AgGaS2, to investigate the phase transition at about 42 kbar. The crystal of AgGaS2 is tetragonal with the space group I4̄2d having the cell dimensions a=5.7603(6) and c=10.299(2) Å under the ambient pressure. The high-pressure form has a similar unit cell to that of the ambient pressure form. The diffraction pattern around the [221̄] zone axis at 47 kbar indicated that the high pressure form has weak but clear h
h
l reflections which do not satisfy the systematic absence condition, 2h+l=4n, for the space group I4̄2d. It has been concluded that the diamond glide planes parallel to {110} present in the ambient pressure form disappear in the high pressure form.
Crystal Growth of Bi4Ge3O12 by Horizontal Bridgman Techniques Using Gas Jets and Its Heat Transfer Analyses
Authors: Kawano Katsuyasu , Nakata Ryouhei , Sumita Minoru
Published: March 2014

Non-hygroscopic, high radiation absorptivity scintillation crystals of BGO (Bi4Ge3O12) have been grown by the horizontal Bridgman (HB) method using very sharply focused gas jets as a heat source. On the basis of a one-dimensional time-dependent heat transfer model, simulation analyses have been made to examine the validity of this method. Sharply focused burner jets allow this model to be realized under the assumption that the melt region is concentrated in a cross-sectional area which provides both narrow width and depth compared with the boat length.
Systematic Aspects of the Electronic Structure of 3d Transition-Metal Compounds
Authors: Fujimori Atsushi , Saitoh Tomohiko , Mizokawa Takashi , Bocquet Antoine E.
Published: March 2014

Systematic changes in the electronic structure of 3d transition-metal compounds with varying chemical compositions are studied by photoemission spectroscopy and configuration-interaction cluster-model analysis. The changes consist of (i) the smooth variation of model parameters such as the charge-transfer energy Δ and the d-d Coulomb repulsion energy U with atomic number and valence and (ii) the apparently irregular multiplet corrections to Δ and U, which are functions of the nominal electron number. These systematics are reflected upon the band gaps, covalency and character of doped carriers in transition-metal oxides and chalcogenides, and upon the optical absorption spectra and the ionization energies of substitutional transition-metal impurities in semiconductors.
Theoretical Study of Magnetic Ordering of Cu2Sb-type Intermetallic Compounds
Authors: Motizuki Kazuko , Suzuki Masakatsu , Shirai Masafumi
Published: March 2014

Electronic band structures of the Cu2Sb-type intermetallic compounds are calculated by using a self-consistent augmented plane wave (APW) or a linearized APW (LAPW) method. In order to clarify the driving forces for different kinds of magnetic orderings in the Cu2Sb-type compounds, the instability of the non-magnetic phase against formation of the magnetic orderings are studied on the basis of the Hubbard Hamiltonian. The magnetic phase diagram is constructed as a function of the intra-atomic Coulomb interaction and the electron number. The bonding nature of the electronic band near the Fermi level as well as a nesting effect of the Fermi surface plays the important role in causing the different kinds of magnetic orderings observed in the Cu2Sb-type compounds.
First-Order Magnetic Phase Transitions Observed in bct FeRh–Pt, Pd Systems
Authors: Miyajima Hideki , Yuasa Shinji , Otani Yoshichika
Published: March 2014

FeRh1-x
Pt
x
and FeRh1-y
Pd
y
systems with body-centered tetragonal (bct) structure were prepared and the magnetic phase diagrams were determined in a temperature-composition plane. The axial ratio c/a increases with substituting Pt or Pd for Rh. The alloys with 0.25≤x≤0.75 or 0.3<y≤0.5 undergo a first-order transition from antiferromagnetic to paramagnetic behaviours by heating above room temperature. The transition is deeply related to the nature of itinerant electron system with anisotropically distorted lattice. The magnetic behaviours were interpreted in terms of magneto-volume effect and tetragonal elongation effect in the framework of the spin fluctuation theory.
Core Absorption Magnetic Circular Dichroism, Photoemission and Inverse Photoemission of MnAlGa and Mn2Sb
Authors: Suga Shigemasa , Kimura Akio , Imada Shin , Kanomata Takeshi , Kaneko Takejiro , Miyahara Tsuneaki , Kagoshima Yasushi , Muto Sadatsugu , Park S.-Y. , Maruyama Hiroshi
Published: March 2014

Electronic structures of ferromagnetic MnAlGe and ferrimagnetic Mn2Sb have been studied by ultraviolet and X-ray Photoemission spectroscopy (UPS, XPS) as well as by X-ray core absorption (XAS) and VUV inverse photoemission (IPES) spectroscopy. Magnetic circular dichroism (MCD) of the Mn 2p core XAS is also measured. Different spectral features from the nonequivalent Mn sites are clarified. The valence band spectra are discussed in comparison with recent band calculations.
Atomic Imaging, Atomic Processing and Nanocharacterization of CuInSe2 Using Proximal Probe Techniques
Authors: Kazmerski Lawrence L.
Published: March 2014

Defects play a dominant role in the determination of the electro-optical properties of single-crystal and polycrystalline CuInSe2. This paper examines the fundamental nature of point and grain boundary defects in this Cu-ternary semiconductor and, for the first time, provides direct evidence underlying the defect chemistry. Special scanning probe microscopy (SPM) techniques are used for real-time atomic imaging, atomic processing (single-atom manipulation), and nanoscale characterization of the same regions of the sample. The (220)-tri-elemental, p-rype surfaces are examined and imaged. Cu-, In-, and Se-vacancies are created using combined, pulsed electric (SPM tip-surface), and single-wavelength photon fields for selected, single-atom removal. The electro-optical characteristics of these defects (before and after creation) are examined using SPM-based nano-photoluminescence and nano-cathodoluminescence techniques that provide information in the same nanometer regime. Bulk photoluminescence spectra are compared and interpreted with respect to these data that give first time direct, atomic-level correlations. In addition, the healing of these point defects by the placement of single intrinsic atoms of the same type at the vacancy sites is accomplished using the atomic processing techniques. The electronic defect levels are verified and correlated with the atomic-scale observations. Finally, donor and acceptor defects, Cu and Se vacancies, Cu at In sites (CuIn) and Se at Cu sites (SeCu), are created, evaluated, and characterized. The placement of the acceptor heteroimpurity oxygen at Se vacancies is also examined. This is done both at isolated Se vacancies and at vacancies along electronically active grain boundaries. The passivation of these regions (by p-type doping of the grain boundary) is evaluated using nanoscale electron-beam induced-current (NEBIC), and newly-developed, SPM-based minority-carrier spectroscopy techniques. This paper reports, for the first time, the engineering of these defects on the atomic scale, and complements these results with the direct evaluation of the atomic manipulations using nanoscale electro-optical characterization methods.
Magnetic Properties of Pseudo-binary Fe1-xCoxGe2 Alloys
Authors: Shiraishi Hiroshi , Hori Tomiei , Kanematsu Kazuo
Published: March 2014

Magnetic susceptibility measurements ascertained three magnetic phase, A.F. I, A.F. II and A.F. III for C16 type Fe1-x
Co
x
Ge2 alloys. The Néel temperature decreases with increasing x. The 2nd magnetic transition between A.F. I and A.F. II vanishes at x≈0.3. The A.F. III is found in x≧0.3 at low temperature. The magnetic phase diagram of this system was illustrated.
Pressure Effect on the Magnetic Transition Temperatures of Mn7Sn3Ge and Mn7Sn2Ge2
Authors: Ohta Satoru , Hagiwara Naoto , Fujii Seiji , Yoshida Hajime , Kaneko Takejiro , Anzai Shuichiro , Matoba Masanori
Published: March 2014

The pressure (P) derivative of the ferrimagnetic Curie temperature dT
C/dP for the Ni2In-type Mn7Sn4-z
Ge
z
is determined to be dT
C/dP=(1.8±0.1)-(0.4±0.1)z K/kbar. The signs of the pressure derivatives dT
f/dP are negative for z=0 and 0.4, where T
f is the transition temperature from the spin-glass like state to the ferrimagnetic one. These pressure effects are discussed on the basis of the interaction curve for antiferromagnetic Mn alloys.
Pressure Effect on Curie Temperature in MnZnSb
Authors: Matsuzaki Hiroyasu , Endo Shoichi , Notsu Yukio , Ono Fumihisa , Kanomata Takeshi , Kaneko Takejiro
Published: March 2014

Pressure dependence of the Curie temperature in the ternary intermetallic compound, MnZnSb, has been investigated in a high pressure region up to 7.5 GPa by monitoring the electric resistance change. Anomalously large increase of T
c with increasing pressure was observed, with the increasing rate of dT
c/dP=28 K/GPa. This anomalously large positive pressure effect on T
c can be explained by considering the superexchange between Mn-Mn atoms along the c-axis.
RKKY Interaction in Transition-Metal Intercalation Compounds of 1T-Type TiS2
Authors: Suzuki Naoshi , Teshiam Tatsuya , Motizuki Kazuko
Published: March 2014

For intercalation compounds of TiS2 RKKY coupling is calculated by using the first-principles band structure of TiS2 and by assuming the rigid band model. As a function of distance the RKKY coupling shows a characteristic feature depending on the concentration of the intercalant atom. In particular the RKKY coupling along the c-axis is much smaller than that in the c-plane reflecting two-dimensional character of the band structure of TiS2.
Magnetism of (Fe, Co)–Se System with a NiAs-type Structure
Authors: Sato Masaki , Kamimura Takashi , Takahasi Hiroki , Mori Nobuo , Sato Takashi , Sninohara Takeshi
Published: March 2014

High pressure X-ray and zero-field NMR measurements were made on (Fe1-x
Co
x
)7Se8. A pressure-induced phase transition takes place up to the magnetic critical concentration x∼0.6 at room temperature. The Co atom as well as the Fe atom possesses a magnetic moment for x<0.6. These results are discussed in view of a close correlation between the magnetism and the lattice spacing c in these compounds.
X-Ray Absorption Study of the Metal-Nonmetal Transition in NiS and Ni1-xMxS (M=Fe and Co)
Authors: Nakamura Motohiko , Namatame Hirofumi , Fujimori Atsushi , Sacchi Maurizio , Fuggle John C. , Misu Akira , Mamori Takeshi , Tamura Hikaru , Matoba Masanori , Anzai Shuichiro
Published: March 2014

We have studied the electronic structure of NiS using Ni 2p X-ray absorption spectroscopy and subsequent clustermodel analysis. The results indicate that with Fe substitution or with decreasing temperature, the S 3p-to-Ni 3d chargetransfer energy increases and the Ni 3d-S 3p transfer integral decreases leading to the increase in the band gap and with Co substitution the band widths increase through the Ni 3d-to-Co 3d hybridization leading to the collapse of the band gap.
Synthesis and Some Physical Properties of a New Series of Layered Selenides (LnO)CuSe (Ln=Lanthanides)
Authors: Ohtani Tsukio , Hirose Masatomo , Sato Tatsuya , Nagaoka Kazuhiro , Iwabe Makoto
Published: March 2014

A new series of layered selenides (LnO)CuSe (Ln=La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Y) with (LaO)AgS-type structure was prepared. All the compounds were semiconductors. Magnetic susceptibility measurements revealed that the lanthanide ions are in the trivalent state and the values of Weiss temperature θ lie within ±15 K for all the compounds. The preparation and the electrical resistivity of (LaO)Cu(S1-x
Se
x
) (0≤x≤1) and (La1-x
Sr
x
)OCuSe (0≤x≤0.2) systems are also reported.
High-Field Magnetization Study of Sm2Fe17Nx and Related Compounds
Authors: Shiomi Jun , Kato Hiroaki , Iriyama Takahiko , Yamada Motohiko , Kido Giyuu , Nakagawa Yasuaki
Published: March 2014

Magnetic and crystallographic properties of Sm2Fe17N
x
with x>3.0, nitrogenated by using a mixed gas of NH3 and H2, have been investigated by comparing the results of two groups of samples: as-nitrogenated samples which contain hydrogen (0.2 to 0.4/f.u.) and annealed samples which are hydrogen-free. The lattice constant c of the Th2Zn17 structure of the hydrogen-free sample is found to be slightly smaller than that of hydrogen-contained sample, the former value, however , being still larger than that of Sm2Fe17N3.0. The saturation magnetization increased slightly by the dehydrogenation treatment, although it is still considerably smaller than that of Sm2Fe17N3.0.
Preparation Techniques for Thin Film Solar Cell Materials: Processing Perspective
Authors: Başol Bülent M.
Published: March 2014

I-III-VI2 compound semiconductors are important photovoltaic (PV) materials with electrical and optical properties that can be tuned for optimum device performance. Polycrystalline thin films of ternary and multinary compounds from the Cu (In, Ga) (Se, S)2 family have already yielded laboratory size solar cells with over 15% efficiency. Large area PV modules with over 10% efficiency have also been demonstrated using these materials. In this contribution we briefly review the preparation techniques for thin film I-III-VI2 compounds with an emphasis on Cu(In, Ga)Se2 and discuss certain characteristics of these films that are important for good solar cell performance.
Stoichiometric ESR Peak in Spinel-Type Clay Mineral Ion [AlO4Al12(OH)24(H2O)12]7+ by Intercalation of Mn2+ Ion
Authors: Kawano Katsuyasu , Buckmaster Harvey A.
Published: March 2014

The ESR invetigations have been made in the molar ratio range 1≤(Mn/Al)≤ 10% for a Mn2+ doping polyoxocation [AlO4Al12((OH)24(H2O)12]7+ formed upon the base hydrolyses that can be utilized as a kind of modelling crystal in clay mineral pillaring agents. The ratio of the axial Mn2+ to the paired Mn2+ centers had a maximum around the stoichiometric concentration 1/13%. This fact has been explained by connecting a concentration proportional model with a magneticaly condensed model, respectively, in each side of the boundary of the 1/13 concentration.
Photoemission Study of the Electronic Structure of the Ferromagnetic Cr1-δTe System
Authors: Shimada Kenya , Saitoh Tomohiko , Namatame Hirofumi , Fujimori Atsushi , Matoba Masanori , Hatakeyama Kazuo , Anzai Shuichiro
Published: March 2014

The electronic structure of Cr1-δTe (δ=0.05, 0.25, 0.375) has been studied by photoemission spectroscopy. Structures near the Fermi level are qualitatively explained by the density of states (DOS) given by band-structure calculations, but significant discrepancies exist in the higher binding energy region. Configuration-interaction cluster-model calculations have been performed and the overall experimental features have been explained, indicating significant electron correlation effects in these compounds.
Zeeman-Tuning of Heterostructures Consisting of Semimagnetic and Non-Magnetic Semiconductors
Authors: Furdyna J. K. , Luo H. , Dobrowolska M.
Published: March 2014

Conduction and valence band edges in semimagnetic semiconductors (e.g., Zn1-x
Mn
x
Se) undergo enormous Zeeman shifts when a magnetic field is applied, reaching values in excess of 100 meV at low temperatures. We discuss the consequences of this effect for heterostructures consisting of magnetic and nonmagnetic semiconductors, where such Zeeman shifts provide the ability of tuning band alignments at the interfaces of the constituent materials. As illustrative examples of such Zeeman tuning, we discuss spin superlattices, magnetic-field-induced type I→type II conversion, mapping of probability distributions in semiconductors, and opportunities for spin lifetime determination.
New Multinary Semimagnetic Semiconductors for Faraday Rotation Magnetic Field Sensors
Authors: Nikitin P. I. , Grigorenko A. N. , Savchuk A. I. , Lyakhovich A. N. , Medynski S. A.
Published: March 2014

Multicomponent semimagnetic semiconductors are studied for sensor applications. Chemical content of these materials is optimized for sensors working at wavelengths of 633, 670, 850, 1300 nm. The main characteristics of semimagnetic semiconductors are analyzed and their advantages are shown. Sensors working at wavelength of 670 nm are constructed.
Preparation and Properties of Cd1-xMnxSe Microcrystallites Embedded in SiO2 Glass Films
Authors: Yanata Kohei , Suzuki Kyoichi , Oka Yasuo
Published: March 2014

Cd1-x
Mn
x
Se microcrystallites have been prepared by the rf-sputtering method. Subsequent annealing was carried out in an Ar atmosphere. In the presence of magnetic field, the photoluminescence spectra from the Cd1-x
Mn
x
Se microcrystallites shift towards the low energy side due to the exchange interaction of the exciton with contained Mn2+ ions in the microcrystallites. Observed red shifts in the high magnetic fields deviate from the Brillouin function-like dependence which is caused by the single Mn2+ ions. The results indicate that the role of the Mn2+ pairs and the antiferromagnetic interaction between the Mn2+ ions are more significant in the microcrystallites than in bulk crystals.
Far-Infrared Electron Spin Resonance of Cd1-xCoxM (M=Te and Se) in High Magnetic Fields
Authors: Hamamoto Terufumi , Adachi Nobuyasu , Mogi Iwao , Kido Giyuu
Published: March 2014

The ESR measurements of Co-based diluted magnetic semiconductors were carried out in the far-infrared range using pulsed high magnetic fields up to 30 T. The g-factor of Cd0.98Co0.02Te was determined to be g
b
*=2.294±0.003, and the zero-field splitting parameter 2D of Cd0.99Co0.01Se was directly determined to be 0.9±0.1 cm-1. These results were explained by the energy-level diagrams of a single Co2+ ion in a crystal field.
T(x) Diagram of the (MnTe)1-x–(Ga2Te3)x System
Authors: Garbato L. , Geddo-Lehmann A. , Ledda F. , Devoto M.Cannas
Published: March 2014

The phase diagram of the semimagnetic system (MnTe)1-x
-(Ga2Te3)
x
has been determined from SEM, DTA, X-ray and EDS investigations. It has been found that a miscibility gap exists for x<0.50, while for x≥0.50 compositions the two chalcogenides form, at high temperature, a complete solid solution. A structural characterization of the adamantine phase MnGa2Te4 is also reported.
Photoluminescence Study of Zn0.99Mn0.01S
Authors: Joshi N. V. , Martin J. M. , Quintero P.
Published: March 2014

Photoluminescence study of Zn
x
Mn1-x
S has been carried out at 77 K and a strong band in the ultraviolet region is observed. Decomposition of the spectrum reveals two luminescence peaks which are associated with the transitions from higher excited states of Mn++ to the ground state 6A1. The position of the band centered at 3.17 eV is temperature independent and could be considered as the characteristic emission feature of manganese based high band gap semiconductors. Energy transfer mechanism also explains different structures in the samples prepared by different methods.
Fabrication and High-Field Magneto-Absorption Study of CdTe/Cd1-xMnxTe Multiple Quantum Wells
Authors: Akinaga Hiroyuki , Ando Koji , Yosnida Sadafumi , Miura Noboru
Published: March 2014

The high-field magneto-absorption spectra of CdTe/Cd1-x
Mn
x
Te multiple quantum wells (x=0.25 and 0.4) were measured in pulsed magnetic fields up to 40 T. The samples were grown by cluster beam deposition method on GaAs substrates and removed from the substrates before the absorption measurement. The investigation showed that the interaction between the excitons in the well layers and the unpaired Mn-spins at the heterointerfaces play the decisive role of the magneto-optical effect in the multiple quantum wells.
Spin Freezing in High Mn Concentrated Cd1-xMnxTe System
Authors: Irie Yuichiro , Jochi Kazuko , Sato Tetsuya , Ohta Eiji
Published: March 2014

Static scaling analysis was made on the nonlinear susceptibility of high Mn concentrated Cd1-x
Mn
x
Te with scaling function: χnl=τβ
g(H/τ(γ+β)/2). With increasing of Mn content the critical exponents β and γ become larger and depart from the values reported for typical spin glass materials. This behavior of the critical exponents suggests that the increase in Mn content causes a change in the spin freezing mechanism from spin glass like one to disordered antifcrromagnetic one at x∼0.46 in Cd1-x
Mn
x
Te.
Temperature Dependence of Inhomogeneous Broadening and Mn2+ Photoluminescence Energy Shift in CdMnTe
Authors: Gregus Jan , Watanabe Junji , Nakahara Jun'ichirō
Published: March 2014

Energy shift in Mn2+ photoluminescence relating with an excitation energy was observed in CdMnTe at low temperature. The shift is considered as the selective excitation of inhomogeneously broadened states. Using this shift we estimated the inhomogeneous broadening of the d-d transition in Mn2+ ions. The temperature dependence of the inhomogeneous broadening is discussed.
Thermal Expansion of Sputtered Amorphous (Hf, Ta)Fe2 Alloys
Authors: Morita Yûji , Murayama Shigeyuki , Hoshi Kensuke , Obi Yoshihisa
Published: March 2014

Thermal expansion of vapor-quenched itinerant-electron ferromagnetic amorphous Hf1-x
Ta
x
Fe2 alloys for 0≦x≦1 has been measured from 20 to 300 K. A positive anomaly has been clearly observed for x=0 at about and below the Curie temperature. Its magnitude decreases with increasing x and almost disappears for x>0.7. These results have been discussed on the basis of the effect of spontaneous volume magnetostriction due to the ferromagnetic moment.
Diffuse Scattering from the Channel-type Composite Crystals Pb1-pCr2S4-p, Sr1-pCr2S4-p and Ba1-pCr2Se4-p (p∼0.3)
Authors: Onoda Mitsuko , Fukuoka Hiroshi , Saito Taro
Published: March 2014

Diffuse streaks which suggested the existence of diffuse scattering planes were observed on electron diffraction patterns of the channel-type composite crystals Pb1-p
Cr2S4-p
, Sr1-p
Cr2S4-p
and Ba1-p
Cr2Se4-p
(p∼0.3). A model of a two-directional disorder of position of filling column part was proposed and examined by application of the extented matrix method. The calculated diffuse intensity distribution explains the broad maxima observed.
Ambipolar Diffusion Length in CuGaSe2 Thin Films for Solar Cell Applications Measured by Steady-State Photocarrier Grating Technique
Authors: Menner R. , Zweigart S. , Klenk R. , Schock H. W.
Published: March 2014

The steady-state photocarrier grating technique is used to measure the transport properties of polycrystalline CuGaSe2 thin films. The influence of composition and growth temperature is analysed in bilayers grown exactly the same way as absorbers for solar cells. The photocurrent losses in solar cells in `substrate' and `superstrate' configuration are related to the measured diffusion lengths.
Diluted Magnetic III–V Semiconductors and Its Transport Properties
Authors: Ohno H.
Published: March 2014

A new class of diluted magnetic semiconductor (DMS) based on III-V compounds and its transport properties are presented. While the new DMS, (In, Mn)As, films exhibiting n-type conduction were all paramagnetic with the Mn–Mn interaction being antiferromagnetic, ferromagnetic interaction between the Mn ions in p-type films manifested itself in the hysteresis in the magnetic field dependence of the Hall resistivity at low temperatures, indicating the presence of ferromagnetic order. This ferromagnetic order was accompanied by paramagnetic response extending to high magnetic fields. The coexistence of remanent magnetization and unsaturated spins (partial ferromagnetic order; asperomagnetism) can be explained by the formation of bound magnetic polarons with partially aligned spins. The ferromagnetic order observed in the (In, Mn)As based heterojunctions is also discussed.
Photoluminescence of MgGa2Se4 Single Crystals
Authors: Kim Hyung-Gon , Park Kwang-Ho , Park Bok-Nam , Lim Han-Jo , Min Suk-Ki , Park Hong-Lee , Kim Wha-Tek
Published: March 2014

Photoluminescence spectra of MgGa2Se4 single crystals grown by the Bridgman method have been investigated. In the photoluminescence spectrum at 10 K of undoped MgGa2Se4 two broad emission bands are observed at 1.39 and 1.62 eV, which are due to D-A pair transitions.
Y2O2S:Tb Phosphor Thin Films Grown by Multisource Deposition and Their Luminescent Properties
Authors: Ohmi Koutoku , Tanaka Shosaku , Kobayashi Hiroshi , Nire Takashi
Published: March 2014

Y2O2S:Tb phosphor thin films have been grown by using a multi-source deposition (MSD) method. Y2O2S thin films grown by MSD method are highly crystallized with hexagonal structure and strongly oriented to <0001> direction. Tb doped Y2O2S thin films show an efficient green photoluminescence. The growth process of Y2O2S:Tb thin films is also discussed.
Formation of CuIn(Ga)Se2 Thin Films by Selenization and Application to Solar Cells
Authors: Sato Hiroki , Hama Toshio , Niemi Esko , Ichikawa Yukimi , Sakai Hiroshi
Published: March 2014

Preparation conditions of device-quality CuInSe2 (CIS) and CuIn1-x
Ga
x
Se2 (CIGS) thin films were studied. We formed CIS and CIGS films by annealing different types of precursor films, such as Gu/In stacked films and Cu–In–Se co-deposited films, under H2Se atmosphere. We obtained CI(G)S films with large grain size using precursors prepared at 200°C. The grain sizes of CI(G)S film using stacked precursors were larger than those using co-deposited precursors. Use of co-deposited precursors reduced formation of MoSe2 at Mo/CI(G)S boundary during selenization process. Fill-factor (FF) exceeding 0.7 was obtained for CIS cells using co-deposited precursors prepared at substrate temperature of 200°C.
Angle-resolved Photoemission Study of CdGeAs2 along the \varGamma-N Direction
Authors: Fraxedas J. , Artús L. , Paumier E.
Published: March 2014

A preliminary study of the valence band structure of the ternary chalcopyrite compound CdGeAs2 along the \varGamma-N direction has been carried out by means of normal-emission angle-resolved photoemission spectroscopy (ARPES). Synchrotron light from the Super ACO storage ring in the 16 to 25 eV range was used as excitation source. Our experiments are compared to empirical pseudopotential method (EPM) calculations showing a good agreement.
Red Electroluminescent Devices Using Mn-Doped CdS(Se)– and CdTe–ZnS Superlattices
Authors: Hikida Kyoko , Ishino Kenei , Ishida Akihiro , Kiichi Tokutsuka , Nakamura Takato , Fujiyasu Hiroshi
Published: March 2014

Mn-doped CdSSeTe–ZnS superlattices (SLs) have been prepared by a hot wall technique, and double insulating electroluminescent devices of the SL layers have been prepared. The red shifted emission of 10–100 nm wavelength have been observed due to the high strain by the large lattice mismatches (7.5–16%). The characteristics of the most shifted one (CdTe–ZnS case) are the peak photon wavelength of 675 nm and the luminance of 450 cd/m2.
II–IV–V2 Semiconductors: Investigations and Potential Applications
Authors: Rud' Yu. V.
Published: March 2014

This paper is review of our previous work on the anisotropy of the photosensitivity of diode structures on the II-IV-V2 single crystals with the chalcopyrite structure. The photosensitivity spectra of the diodes were analyzed as a function of the polarization and the illumination geometry. It was established that the polarity of the photocurrent of the structures with two opposed barriers in II-IV-V2 single crystals changed with the polarization of the incident light and the photopleochroism coefficient exceeded. 100%. The investigated structures could be used both as wide-range and selective photodetectors and also as photoanalysers of linearly polarized radiation.
Semiconductor Electron-Beam-Pumped Lasers Based on ZnCdS Compounds
Authors: Gribkovskii V. P. , Gurskii A. L. , Davydov S. V. , Lutsenko E. V. , Kulak I. I. , Mitkovets A. I. , Yablonskii G. P. , Gremerik V. F.
Published: March 2014

The parameters of semi conductor electron-beam-pumped lasers based on ZnCdS compound made by using the conventional silver mirrors and new type microrelief mirrors are described. The use of microrelief mirror instead the full-reflected silver mirror permits, all other things being equal, increasing the power and efficiency of radiators by about one order of magnitude.
Preparation of AgGaS2 Thin Films by Excimer Laser Deposition
Authors: Uchiki Hisao , Hirasawa Hiroyuki , Machida Osamu
Published: March 2014

AgGaS2 thin films were prepared on quartz substrates by means of XeCl excimer laser deposition from a mixture target of Ag2S and Ga2S3. Dependence of film quality on laser intensity, laser repetition rate and a mole ratio of Ag2S to Ga2S3 in a target was studied.
Characterization of CuInSe2 Thin Films by Photoluminescence Measurements
Authors: Kushiya Katsumi , Yamada Akira , Hakuma Hideki , Sano Hideki , Konagai Makoto
Published: March 2014

PL measurement has been clearly demonstrated to be an effective technique not only to evaluate the quality of CIS-based thin films but also to investigate the CIS formation process during the selenization stage. The studies investigating the dependence of the PL spectrum on the excitation intensity and the effect of post-annealing in air clarified that the PL spectrum of CIS thin films was dominated by a donor-acceptor (D-A) pair emission and even in a 5 min post-annealing, the PL peak of as-deposited CIS films drastically shifted from 0.93 eV (1340 nm) to about 0.89 eV (1400 nm).
Effects of the Cations on the Raman Spectra of Sulphur Defect Chalcopyrites
Authors: Tiginyanu I. M. , Lottici P. P. , Razzetti C. , Gennari S.
Published: March 2014

We report the Raman spectrum of defect chalcopyrite compounds CdAl2S4, CdGa2S4, ZnGa2S4 and of the isostructural mixed compounds Zn0.7Cd0.3Al2S4, ZnGa0.2Al1.8S4 and ZnGa0.8Al1.2S4. The role of the cations on the vibrational dynamics is discussed in terms of simple models.
Synthesis and Raman Characterization of Some Selenium Defect Chalcopyrite Alloys
Authors: Attolini G. , Lottici P. P. , Razzetti C.
Published: March 2014

We have synthesized by CVT techniques some ternary and quaternary selenide compounds of the defect chalcopyrite families Zn
x
Cd1-x
Ga2Se4, Zn
x
Cd1-x
In2Se4, ZnGa
x
In2-x
Se4 and CdGa
x
In2-x
Se4 These systems have been investigated to determine the effect of the cation mixing on the Raman spectra. The Zn–Cd mixing in isomorphous selenium compounds confirms the results on mode behaviour found for corresponding sulphides, while in non-isomorphous compounds no clear trend is manifested. The In–Ga substitution on the complete range of the solid solution suggests a mixed one- and two-modes behaviour.
EXAFS Studies on (Cu, In)Se2
Authors: Yamaguchi Hirotaka , Kuwahara Yuji , Oyanagi Hiroyuki , Nakanisni Hisayuki , Irie Taizo
Published: March 2014

The local structure of chalcopyrite (Cu, In)Se2 has been investigated by extended X-ray absorption fine structure (EXAFS) measurements on the Cu K- and the Se K-edges. The values of the Cu-Se and the In–Se bond lengths were determined for various values of the Cu/In ratio, and the Se position parameter u was estimated from the obtained bond lengths and the lattice parameters. For the sample with Cu/In=0.96, the u-values obtained from the Cu–Se and the In–Se bond lengths are consistent with each other, and it was determined as 0.223. On the other hand, the relation of these structural parameters show a deviation from the values expected for the chalcopyrite structure as the Cu/In ratio deviates from 0.96. These results indicate that the chalcopyrite single phase is obtained within a narrow range of the Cu/In ratio around 0.96 while a structural disorder due to either the compositional fluctuation or the multiphase occurs as the Cu/In ratio deviates from 0.96.
Resonant Raman Scattering and Excitonic Polariton States in CuGaS2
Authors: Tsuboi Nozomu , Uchiki Hisao , Ishikawa Hideyuki , Iida Seishi
Published: March 2014

Scattering processes and the relevant intermediate state for intense Raman lines appearing in the exciton region spectrum of CuGaS2 under 4765 Å excitation of an Ar+ laser are discussed from measured intensity changes of the lines with temperature as well as photon energy of excitation. Experimental results are consistent with the previous interpretation that the line at 2.504 eV corresponds to a three-phonon Raman scattering in resonance with the upper-branch excitonic polariton (UBP) state. The line at 2.509 eV is thought to correspond to a two-phonon Raman scattering in resonance with the UBP state.
Optical Absorption and Raman Scattering of Spinel Type Semiconductor ZnAl2S4
Authors: Kulikova O. V. , Moldovyan N. A. , Popov S. M. , Radautsan S. I. , Siminel A. V.
Published: March 2014

In this paper investigations of optical absorption and Raman scattering (RS) in ZnAl2S4 cubic modification (α-phase) are presented. An increase of the exciting radiation photon energy causes decrease of the E
g mode intensity compared to the totally symmetric A
1g mode. The minimum intensity of E
g line normalized to A
1g mode reflect band gap value. The value E
g
ind(300 K)=3.2 eV which was determined by such method is in a good agreement with the data from optical absorption measurements (E
g
ind(80 K)=3.50 eV and E
g
ind(300 K)=3.42 eV).
Optical Absorption Study of Laser-Evaporated Cu-Ternary and Quaternary Thin Films
Authors: Kindyak V. V. , Kindyak A. S. , Gremenok V. F.
Published: March 2014

The fundamental transition energies of highly oriented, single-phase, laser-evaporated CuGa
x
In1-x
Se2 (x=0; 0.2; 0.5; 1) thin films were determined using interferential reflectivity and transmission in the system air-film-substrate-air in the range 400–1700 nm. From the detailed analysis of the structure of the fundamental absorption edge, values for the direct allowed valence to conduction band transition energies and corresponding valence band splitting due the crystal-field and spin-orbit interaction were estimated. The optical structure, which was observed at higher energies is attributed to the transitions from the copper d-level to conduction band.
Deep Levels in Undoped and ErCl3-Doped TlGaS2 Single Crystals
Authors: Song Ho-Jim , Yun Sang-Hyun , Kim Wha-Tek , Min Suk-Ki , Lim Han-Jo , Park Hong-Lee
Published: March 2014

TlGaS2 and TlGaS2:ErCl3 single crystals were grown by the Bridgman technique. The optical energy band gaps and the deep levels of the as-grown crystals were investigated by the optical absorption, thermally stimulated current (TSC), and, photo-induced current transient spectroscopy (PICTS) spectra. The electron traps (0.18±0.01 eV and 0.23±0.01 eV) and the hole traps (0.36±0.02 eV and 0.66±0.02 eV) are observed in TlGaS2 single crystal. In the case of TlGaS2:ErCl3 single crystal, two deep levels as donors are located at 0.15±0.01 eV and 0.25±0.01 eV and, one deep level as acceptor, at 0.64±0.02 eV.
Deep Region Emissions of CuGaS2 Crystals
Authors: Yagi Masakazu , Terasako Tomoaki , Tsuboi Nozomu , Iida Seishi
Published: March 2014

The broad emission bands appearing at 6700 Å, 7500 Å and 8600 Å were discussed in terms of preparation processes of epitaxial films and bulk crystals. For the emission at 7500 Å showing spectral shifts during decay, characteristic to donor-acceptor-pair type recombinations, possible relation is pointed out to sulfur vacancies and interstitial halogen (Cl or I) atoms in films or bulk crystals.
Green Emission in CdS Films Deposited on CdInGaS4 by Evaporation Method
Authors: Ando Shizutoshi , Endo Saburo , Nakanishi Hisayuki , Toyoda Taro , Irie Taizo
Published: March 2014

The heterojunction of CdS/CdInGaS4 was prepared by evaporation of CdS films on CdInGaS4 single crystals. Photoluminescence of the CdS/CdInGaS4 showed very intense green emission at 77 K. From the results of X-ray diffraction experiment, it was found that the intense green emission was observed only when the CdS film was highly oriented to CdInGaS4 (009) plane. It is considered that an edge emission in CdS can be enhanced by laminated CdInGaS4.
The Recombination in Zn, Cd and Hg-Doped CuAlS2
Authors: Lipnitskii V. I. , Savchuk V. A. , Korzun B. V. , Makovetskii G. I. , Popelnjuk G. P.
Published: March 2014

Single crystals of CuAlS2 were grown by the chemical vapour transport using iodine as a transporting agent and doped by the elements Zn, Cd and Hg in the growth process or in atomosphere of vapour. The cathodoluminescence investigations of annealed samples at the temperatures 77 and 300 K allowed to determine the recombination mechanism. The outlook of this material for light-emitting devices is presented.
Room Temperature Tailoring of Electrical Properties of Ternary and Multinary Chalcogenide Semiconductors
Authors: Cahen David , Chernyak Leonid , Gartsman Konstantin , Lyubomirsky Igor , Triboulet Robert
Published: March 2014

Semionic behaviour is demonstrated in certain ternary and multinary semiconductors, by following the effects of application of external electric fields at ambient temperature. We find that this can lead to stable, local changes in their microchemical composition and, via resulting changes in carrier concentration, in their electronic properties. Thus, actual device structures are embedded in the material. We summarize these results and our understanding of the mechanisms involved.
Variable Range Hopping Conduction in CuInSe2 in the Presence of a Coulomb Gap
Authors: Albornoz J. G. , Hernández E. , Wasim S. M. , Bocaranda P.
Published: March 2014

Electrical conduction by Mott's variable range hopping mechanism and cross-over above liquid helium temperatures in the same samples to Efros and Shklovskii's type conduction in the presence of a Coulomb gap is observed in p-type CuInSe2. The behaviour of the hopping parameters is discussed.
The Application of van Doorn Apparatus to the Selenization of CuInSe2
Authors: Nakashima Y. , Hashimoto H. , Chiba Y. , Mori Y.
Published: March 2014

Thin film polycrystalline CuInSe2 (CIS) has been fabricated through a selenization process using the van Doorn apparatus, in which Se vapor pressure is in equilibrium with control gas pressure. The film properties of the chalcopyrite crystal structure, the band-gap energy, the dependence of majority carrier type and its concentration on the Cu/In ratio, and the photoluminescence spectrum were tested. The apparatus appears applicable to the fabrication of chalcopyrite CIS thin films of solar cells grade.
Effect of Excess Ca/Cu on Phase Formation in Bi-2223 Superconductors
Authors: Singh S. K. , Singh R. K.
Published: March 2014

We have explored the effect of excess Ca and Cu addition on superconductivity in Bi–Pb–Sr–Ca–Cu–O system. A single phase 110 K high T
C superconductor has been synthesized with Sr, Ca and Cu in the ratios of 1.6:2.4:3.6, respectively. There are two consequences, when Ca and Cu are in excess. Firstly, a single phased 110 K high T
C superconductor is formed with the above mentioned ratio and secondary, the remaining Ca and Cu forms superconducting 2212 phase, non-superconducting Ca2PbO4, Ca2CuO3 and unreacted CuO. The XRD patterns and the results of the resistivity measurements are presented.