bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Mg occupation site in MOCVD‐ and MBE‐grown Mg‐doped InN using X‐ray absorption fine‐structure measurements
Authors: Miyajima Takao , Uemura Shigeaki , Kudo Yoshihiro , Kitajima Yoshinori , Yamamoto Akio , Muto Daisuke , Nanishi Yasushi 
Published: April 2008

AbstractWe analyzed the atomic structure around Mg atoms in MOCVD‐ and MBE‐grown Mg‐doped InN using Mg K‐edge X‐ray absorption fine‐structure (XAFS) measurements. Our experimental data closely fit to the simulated data in which Mg atoms occupy the substitutional sites of In atoms. From this result, we conclude that Mg atoms essentially occupy not N atoms sites but In atoms sites, meaning that Mg atoms can act as acceptors in InN. We believe that observations of p‐type conductivity are prevented by problems such as carrier compensation and electron accumulation at the surface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOCVD growth of GaN‐based materials on ZnO substrates
Authors: Wang Shen‐Jie , Li Nola , Park Eun‐Hyun , Feng Zhe Chuan , Valencia Adriana , Nause Jeff , Kane Matthew , Summers Chris , Ferguson Ian 
Published: April 2008

AbstractThe metalorganic chemical vapor deposition (MOCVD) growth of GaN based materials on ZnO substrates has numerous technical issues that need to be investigated and resolved. These include the thermal stability of ZnO, out‐diffusion of Zn/O from the ZnO into the epilayers, and H2 back etching into the ZnO all of which can cause poor film quality. Cracks and pinholes were seen in the epilayers, leading to the epilayer peeling off. In this study, good quality InGaN films with a wide range of indium incorporation have been grown on (0001) ZnO substrates by MOCVD. No indium droplets and phase separation were observed even at high indium concentrations. The optical microscopy and field‐emission scanning electron microscopy revealed a mirror‐like InGaN surface with no evidence of indium droplets on the surface. Photoluminescence (PL) showed broad InGaN‐related emissions with peak energy lower than the calculated InGaN band gap, possibly due to Zn/O impurities diffused into InGaN from the ZnO substrate. More recently, Al2O3 coated ZnO substrates have been employed for growth to limit Zn diffusion as well as assist epilayer growth. HRXRD result shows that a single crystal InGaN film has been successfully grown on an annealed Al2O3 coated ZnO substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy relaxation processes of photo‐generated carriers in Mg doped (0001)GaN and (1‐101)GaN
Authors: Saida J. , Kim E. H. , Hikosaka T. , Honda Y. , Yamaguchi M. , Sawaki N. 
Published: April 2008

AbstractEnergy relaxation processes of photo‐generated excess carriers in Mg doped GaN epitaxial layers were investigated at room temperature, with photoluminescence intensity correlation method using femto‐second pulse laser as the excitation source. The decay curve was well fitted by exponential decay with two time constants. The slow process of the order of 100 ps was attributed to the energy relaxation of electrons in the conduction band, while the fast process of the order of several pico‐seconds was attributed to the capture process in the impurity band near the valence band. Little difference has been found out between the results for (0001)GaN and those for (1‐101)GaN. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Marked improvements in electrical and optical properties for MOVPE InN annealed at a low temperature (300 °C) in O2 atmosphere
Authors: Sugita K. , Nagai Y. , Matsuoka D. , Hashimoto A. , Harima H. , Yamamoto A. 
Published: April 2008

AbstractWe have found that the material quality of MOVPE InN can be markedly improved after the annealing in the air at around 300 °C. By the annealing in the air, carrier concentration is reduced by about one order of magnitude. In accordance with the carrier reduction, PL intensity is increased and PL peak energy is shifted to the lower energy side by about 0.06 eV for the film annealed for 3 h. The reduction of carrier concentration is also conformed by the shift of LO phonon‐plasmon coupled mode in the Raman spectrum. The FWHM of the E2 (high) mode is decreased, indicating that the crystalline quality is slightly improved by the annealing. Since the FWHM of X‐ray rocking curve is not changed after the annealing, the improvement by the annealing is concluded not to be in macroscopic scale but microscopic scale. No improvements are found for the samples annealed in the N2 flow. No data that show the chemical oxidation of InN are also found. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonpolar GaN layers grown by sidewall epitaxial lateral overgrowth: optical evidences for a reduced stacking fault density
Authors: Paskov P. P. , Monemar B. , Iida D. , Kawashima T. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. 
Published: April 2008

AbstractNonpolar a ‐plane and m ‐plane GaN layers grown by MOCVD employing sidewall epitaxial lateral overgrowth (SELO) are studied by photoluminescence (PL) and spatially resolved micro‐PL. The effects of the groove orientations and the groove/terrace width ratio on the emission spectra, particularly on the stacking fault (SF) related emission bands in the 3.29–3.42 eV spectral region, are examined. The PL spectra of both types of nonpolar layers reveal a significant reduction of the defect related emissions when the grooves are oriented perpendicular to the c‐axis of GaN and the groove/terrace width ratio is smaller than one. The suppression of SF formation in the areas where a lateral overgrowth along the [0001] GaN direction occurs is confirmed by micro‐PL measurements showing no SF related emissions over the terrace regions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New nitridation technique for mosaicity control in RF‐MBE InN growth
Authors: Iwao K. , Yamamoto A. , Hashimoto A. 
Published: April 2008

AbstractMosaicity control is necessary for improvement of crystal quality of III‐V nitride semiconductor materials, especially for InN. However, the mosaicity control for both of the tilt and the twist angle fluctuations has not been achieved still now in the direct growth of InN on the sapphire substrate by nitridation. Moreover, the role of nitridation process has not been so much clear from the view point of the mosaicity control. In this paper, we propose a new nitridation technique, two‐step nitridation, combined with the high‐ and the low‐ temperature nitridation to reduce the mosaicity and also to make clear the roles of the nitridation process in the InN growth. As the result of the new nitridation technique, the considerably improvement of the tilt and the twist angle fluctuations has been successfully achieved in the direct growth of InN without any buffer layer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOVPE growth of high quality AlN layers and effects of Si doping
Authors: Thapa S. B. , Hertkorn J. , Scholz F. , Prinz G. M. , Feneberg M. , Schirra M. , Thonke K. , Sauer R. , Biskupek J. , Kaiser U. 
Published: April 2008

AbstractHigh quality AlN layers were grown by MOVPE on c ‐plane sapphire substrates after optimization of various stages of the epitaxial process. AFM measurements revealed a rms surface roughness of 0.2 nm. The FWHM of HRXRD for the (002) and (114) reflections are 25 and 300 arcsec, respectively. This excellent quality is further confirmed by low temperature (10 K) CL spectra with a FWHM of 10 meV.We observed degrading surface and crystal quality of Si doped samples along with increasing in‐plane tensile strain up to a Si concentration of approx. 2 × 1019 cm–3 and thereafter relaxation for higher concentrations as determined by HRXRD, and low temperature CL measurements. Furthermore, we obtained a weak n‐type conductivity, increasing with temperature with an activation energy of about 200 meV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering analysis of GaN with various dislocation densities
Authors: Kitamura T. , Nakashima S. , Nakamura N. , Furuta K. , Okumura H. 
Published: April 2008

AbstractWe characterized GaN crystals with various dislocation densities by micro‐Raman spectroscopy. Defects and Strain for the GaN layer were examined through measurements of the Raman shift and the width of the TO phonon bands. The broadening of Raman bands in GaN crystals occurred as the dislocation density increased. The up‐shift of the peak frequencies corresponding to compressive strain was observed for the heteroepitaxial samples grown by MOCVD and MBE. The in‐plane distribution of defects and strain in epilayers with various dislocation densities was also examined by Raman mapping. The Raman maps showed that the examined phonon frequency and band width in samples fluctuated spatially. The increase of dislocation density in GaN epilayers induced not only the broadening of Raman bands but also increase of fluctuation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Realization of AlGaN/GaN HEMTs on 3C‐SiC/Si(111) substrates
Authors: Cordier Y. , Portail M. , Chenot S. , Tottereau O. , Zielinski M. , Chassagne T. 
Published: April 2008

AbstractCubic SiC/Si (111) template is an interesting alternative for growing GaN on silicon. As compared with silicon, this substrate allows reducing the stress in GaN films due to both lower lattice and thermal expansion coefficient mismatch, and can provide better heat dissipation. In this work, we first developed the epitaxial growth of 3C‐SiC films on 50 mm Si(111) substrates using chemical vapor deposition. AlGaN/GaN high electron mobility transistors were grown by molecular beam epitaxy on these films. Both the structural quality and the behavior of transistors realized on these structures show the feasibility of this approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication and properties of semi‐polar (1‐101) and (11‐22) InGaN/GaN light emitting diodes on patterned Si substrates
Authors: Hikosaka T. , Tanikawa T. , Honda Y. , Yamaguchi M. , Sawaki N. 
Published: April 2008

AbstractInGaN/GaN light emitting diodes (LEDs) were fabricated on semi‐polar (1‐101) and (11‐22) GaN templates which had been grown on patterned (001) and (113)Si substrates, respectively. The GaN templates were of 300 × 300 μm2 discs formed by the coalescence of GaN stripes grown by selective MOVPE method. The n‐type electrode was fabricated on the back surface of the Si substrate. The electroluminescence (EL) peaks were observed around 440 nm and 420 nm in (1‐101) and (11‐22) LEDs, respectively. The full width at half maximum (FWHM) of the peaks at 20 mA were 33 nm ((1‐101) LED) and 21 nm ((11‐22) LED). The emission peak was slightly blue‐shifted at high drive currents, which was smaller than that of conventional c‐plane LEDs. The turn‐on voltage of the diodes was of the order of 3‐4 V. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controlled local filament growth and dissolution in Ag–Ge–Se
Authors: Schindler Christina , Szot Krzysztof , Karthäuser Silvia , Waser Rainer 
Published: April 2008

AbstractMemory cells based on the cation migration and filament formation and rupture in a solid electrolyte have attracted much interest due to low switching voltages and a prospective high scalability. In this study we indirectly visualized the growth and dissolution of the conductive filament in Ag–Ge–Se samples with Ag bottom electrodes by surface analysis with Conductive Atomic Force Microscopy (CAFM). By application of a negative voltage to the inert CAFM tip, conductive filaments were grown on the scanned area and they were dissolved under reversed bias. The local conductivity changes directly corresponded to changes in the topography, i.e. to the filament protrusion and dissolution. Topography changes could be circumvented by limiting the maximum current. By placing the CAFM tip on a random spot on the sample, filaments with a diameter as low as 20 nm were grown by local current–voltage measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coriolis effects in homogeneous and inhomogeneous katabatic flows
Authors: Shapiro Alan , Fedorovich Evgeni 
Published: April 2008

AbstractKatabatic flows along a planar slope in a viscous stably‐stratified fluid are investigated analytically and numerically, with an emphasis on flow features arising from the action of the Coriolis force. Two idealized flow types are considered: turbulent flow along a uniformly cooled slope, and two‐dimensional laminar flow induced by a cold strip of finite width running down the slope. In the case of turbulent flow along a uniformly cooled slope, the downslope velocity exhibits a boundary‐layer structure, but the cross‐slope velocity and buoyancy fields spread inexorably upward. This behaviour is qualitatively similar to that found in laminar flows along a uniformly cooled slope. In contrast, in the two‐dimensional strip flow, a steady state is reached, in which the cross‐slope wind and buoyancy fields vanish far above the slope, but the downslope and slope‐normal velocity fields do not vanish. These latter two flow components comprise two purely horizontal along‐isentrope counter‐flowing currents: an upslope current entering the top of the boundary layer on one side of the strip, and a downslope current flowing out of the boundary layer into the environment on the other side of the strip. The slope‐normal vorticity associated with these currents originates in the stretching of planetary vorticity in a broad zone of convergent flow over the cold strip. Copyright © 2008 Royal Meteorological Society
Improvements of parametric quantum methods with new elementary parametric functionals
Authors: Ruette Fernando , Marcantognini Stefania A. M. , V. Karasiev Valentin , Sánchez Morella 
Published: April 2008

AbstractA series of elementary parametric functionals (EPFs) for resonance integral, electron‐electron repulsion, electron‐nucleus attraction, core‐core interaction, and bond correlation correction were included in the new version of CATIVIC method [Int J Quantum Chem 2004, 96, 321]. In the present work, a systematic way to improve the precision of parametric quantum methods (PQMs) by using several EPFs in the parameterization of a set of molecules is proposed. Based on the fact that a linear combination of elementary functionals from the exact Hamiltonian is also a functional, a linear combination of EPFs has been proved that can enhance the accuracy of PQMs by considering the convex condition. A general formulation of simulation techniques for molecular properties is presented and a formal extension of the minimax principle to PQMs is also considered. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
A spectral technique for random satisfiable 3CNF formulas
Authors: Flaxman Abraham 
Published: April 2008

AbstractLet I be a random 3CNF formula generated by choosing a truth assignment ϕ for variables x1, xn uniformly at random and including every clause with i literals set true by ϕ with probability pi, independently. We show that for any constants 0 ≤ η2,η3 ≤ 1 there is a constant dmin so that for all d ≥ dmin a spectral algorithm similar to the graph coloring algorithm of Alon and Kahale will find a satisfying assignment with high probability for p1 = d/n2, p2 = η2d/n2, and p3 = η3d/n2. Appropriately setting the ηi's yields natural distributions on satisfiable 3CNFs, not‐all‐equal‐sat 3CNFs, and exactly‐one‐sat 3CNFs. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Hitting time of large subsets of the hypercube
Authors: Černý Jiří , Gayrard Véronique 
Published: April 2008

AbstractWe study the simple random walk on the n‐dimensional hypercube, in particular its hitting times of large (possibly random) sets. We give simple conditions on these sets ensuring that the properly rescaled hitting time is asymptotically exponentially distributed, uniformly in the starting position of the walk. These conditions are then verified for percolation clouds with densities that are much smaller than (n log n)‐1. A main motivation behind this article is the study of the so‐called aging phenomenon in the Random Energy Model, the simplest model of a mean‐field spin glass. Our results allow us to prove aging in the REM for all temperatures, thereby extending earlier results to their optimal temperature domain. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Qualitative and quantitative identification of copper oxides
Authors: Su Yea‐Yang , Shemenski Robert M. 
Published: April 2008

AbstractThe quality, thickness, and chemistry of oxides on metal surfaces play a vital role in a variety of applications. Some of these include adhesion of elastomers to metal surfaces, solar cell efficiency, sealing of electronic packaging, reduction of friction during wet drawing, and degree of biocompatibility of biomaterials. However, contradictory results and misidentification of oxide layers on metallic surfaces have caused ambiguity in interpretation of results leading to incorrect use in industrial application. This study will focus on the effect of experimental parameters such as electrolyte composition and concentration, current density, coating, time constant, surface roughness, and concentration of depolarizer on cathodic reduction of oxides on metallic wires to yield precise measurement and correct identification of oxide layers. Copyright © 2008 John Wiley & Sons, Ltd.
Molecular physiology and pathophysiology of lysosomal membrane transporters
Authors: Sagné C. , Gasnier B. 
Published: April 2008

SummaryIn contrast to lysosomal hydrolytic enzymes, the lysosomal membrane remains poorly characterized. In particular, although the genetic study of cystinosis and sialic acid storage disorders led to the identification of two lysosomal transporters for cystine and sialic acids, respectively, ten years ago, most transporters responsible for exporting lysosomal hydrolysis products to the cytosol are still unknown at the molecular level. However, two lines of investigation recently started to fill this gap in the knowledge of lysosomal biology. First, novel proteomic approaches are now able to provide a reliable inventory of lysosomal membrane proteins. On the other hand, a novel functional approach based on intracellular trafficking mechanisms allows direct transport measurement in whole cells by redirecting recombinant lysosomal transporters to the cell surface. After surveying the current state of knowledge in this field, the review focuses on the sialic acid transporter sialin and shows how recent functional data using the above whole‐cell approach shed new light on the pathogenesis of sialic acid storage disorders by revealing the existence of a residual transport activity associated with Salla disease.
Mesozoic and Cenozoic collisional structures of the southern Great Altai
Authors: Chikov B.M. , Zinoviev S.V. , Deyev E.V. 
Published: April 2008

Abstract
We suggest a model of the continental collisional framework of the southern Great Altai (Central Asia) produced by the convergence of the Tuva-Mongolia and Jonggaria terranes (microplates) during the latest Permian-Mesozoic and Cenozoic tectonic activity. The collisional structures in the region classified on the basis of their geometry and deformation style, dynamic metamorphism, and compositions of tectonites are of three main types: (i) mosaic terranes made up of large weakly deformed Paleozoic blocks separated by younger shear zones, (ii) collisional deformation systems involving post-Paleozoic structures, parallel faults oriented along collisional deformation systems, and relict lenses of Paleozoic orogenic complexes, and (iii) isolated zones of dynamic metamorphism composed mostly of collisional tectonites.
Array magnetotelluric soundings in the active seismic area of Northern Tien Shan
Authors: Rybin A.K. , Spichak V.V. , Batalev V.Yu. , Bataleva E.A. , Matyukov V.E. 
Published: April 2008

Abstract
High-density array MT soundings of the crust in the seismically active northern Tien Shan were performed using Phoenix MTU-5 stations in the Bishkek Geodynamic Polygon, at the junction of the Chu basin and the Kyrgyz Range. The MT transfer functions were determined to an accuracy of 1–2% (amplitude) and about 0.5–0.8 deg (phase) in most of 145 soundings. Preliminary analysis of the collected data aimed at estimating the geoelectrical dimensionality. The Bahr decomposition analysis indicated the presence of local 3D structures in the crust of the area superposed on the regional 2D structure.
Time-dependent stress change during failure of rocks
Authors: Belikov V.T. , Shestakov A.F. 
Published: April 2008

Abstract
The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith’s criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure.
Morphostructures and Cenozoic deposits on the right bank of the Kizir River (East Sayan)
Authors: Popova N.N. , Matsera A.V. 
Published: April 2008

Abstract
Study of morphostructures and Cenozoic deposits is important for reconstructing the history of the recent evolution of East Sayan and search for buried gold placers. Regional positive morphostructures of mountains with well-pronounced relief stages have been recognized in the Altai-Sayan area. The upper stage is referred to the Cretaceous-Paleogene; the middle one, to the Miocene-Pliocene; and the lower stage is dated at the Late Pliocene-Early Pleistocene. Negative morphostructures are recognized as a chain of intramontane basins and graben-like valleys of the Transbaikalian type. Troughs in the section bottom are filled with Cretaceous-Paleogene clayey crusts of weathering overlain by Neogene-Pleistocene deposits of complex composition. We studied the sections of Cenozoic deposits in the valleys of the Shinda and Verkhnyaya Chinzheba Rivers and made their palynological description.
Applying an aggregative dispersive dichotomy (ADD) model to parasitic infections in host populations
Authors: Pal P. , Abu-Madi M.A. , Lewis J.W. 
Published: April 2008

AbstractAn aggregative dispersive dichotomy (ADD) model is presented to describe the distribution of parasites in host populations. The ADD model is a mathematical construct which provides two complementary measures extracted from a reformulated negative binomial (NBD) and an inequality model, which combine to capture observed patterns of a parasitic infection. The dispersion element is modelled using the NBD with the threshold set at a parasite level above zero. By applying binomial dichotomy, the host community is divided into two sub-populations, one including hosts harbouring parasites up to the threshold and the other with parasites above the threshold level. Thekparameter, derived from the NBD, provides a cumulative probability. However,kis relatively insensitive to variations in the degree of aggregation, a known feature of the NBD model. The aggregation of parasites above the threshold in the host sub-population is evaluated by using an inequality model which is indexed by a scale-free parameter δ(δ ≥ 1) and provides an accurate measure of parasite aggregation. Applications of this model are made from field and simulated data in wood mouse populations infected with the trichostrongylid nematodeHeligmosomoides polygyrusfrom a woodland site in Surrey.