bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of high performance 3C‐SiC vertical MOSFETs by reducing planar defects
Authors: Nagasawa Hiroyuki , Abe Masayuki , Yagi Kuniaki , Kawahara Takamitsu , Hatta Naoki 
Published: June 2008

AbstractThe planar defect density of 3C‐SiC can be reduced by growing it on undulant‐Si substrates. However, specific stacking faults (SFs) remain, that expose the Si‐face on the (001) surface. These residual SFs increase the leakage current in devices made with 3C‐SiC. They can be eliminated using an advanced SF‐reduction method called switch‐back epitaxy (SBE) that combines polarity conversion with homoepitaxial growth. Vertical metal–oxide–semiconductor field‐effect‐transistors (MOSFETs) are fabricated on 3C‐SiC with SBE, varying in size from a single cell with an area of (30 × 30) μm2to 12,000 hexagonal cells on a (3 × 3) mm2chip. The MOSFET characteristics suggest that currents greater than 100 A are realistic for blocking voltages of 600–1,200 V by increasing the number of cells with reduced cell‐pitch. The combination of blocking voltage capability with a demonstrable high current capacity shows that 3C‐SiC is well‐suited for use in vertical MOSFETs for high‐ and medium‐power electronic applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Slow waves in magnetic metamaterials: history, fundamentals and applications
Authors: Shamonina E. 
Published: June 2008

AbstractMagnetic metamaterials consist of small metallic resonators of the split ring type. Microscopic properties of these structures are governed by near field coupling between individual elements. This strongly anisotropic coupling leads to propagation of slow magnetoinductive waves with the wavelength much shorter than that of the electromagnetic radiation. This opens up novel possibilities of designing miniaturised subwavelength waveguide components and near‐field lenses in a wide range of frequencies, from radio frequencies, with a potential for medical applications in MRI, to the IR and visible range, aiming at fast signal processing. This paper provides an overview of contributions that led to the birth of the subject of magnetic metamaterials. The properties of slow waves on magnetic metamaterials including their dispersion characteristics, excitation and applications are discussed. The emphasis is laid on phenomena such as backward and forward slow waves, polaritonic hybridization of the interaction of a metamaterial with an incident electromagnetic wave yielding negative values of magnetic permeability, the possibility of positive and negative refraction of slow waves as well as mechanisms for near field subwavelength imaging. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopy and imaging of GaAs/InGaAs/GaAs nanowires grown by selective‐area metalorganic vapor phase epitaxy
Authors: Fukui M. , Kobayashi Y. , Motohisa J. , Fukui T. 
Published: June 2008

AbstractWe have performed micro‐photoluminescence (μ‐PL) spectroscopy and imaging of single GaAs/InGaAs/GaAs nanowires (NWs) grown by selective‐area metalorganic vapor phase epitaxy (SA‐MOVPE) on masked GaAs (111)B substrates. Strong emission was observed from both end of the NW dispersed on a Si substrate. Measurements of excitation power dependence and two types of spatially‐ and spectrally‐resolved image revealed that those emissions, located around 1.40 and 1.44 eV, were from InGaAs quantum well embedded in the GaAs NW, and were suggested to be from different region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical study of InAs/GaAs quantum dots with two different environments
Authors: Kaniewska M. , Engström O. , Kaczmarczyk M. , Surma B. , Jung W. , Zaremba G. 
Published: June 2008

AbstractUnusually complex spectra have been obtained for InAs/GaAs quantum dot (QD) structures when studied as a function of applied bias by deep level transient spectroscopy (DLTS). In spite of their complexity, basic processes for electron escape from the QDs have been recognized. We show that due to the variety of transitions involving direct tunneling and more complex thermal transitions, due to QD size fluctuations, and environmental dependent QD carrier population, measurement conditions have to be carefully suited for characterizing transport properties of the QDs. Additionally, on the basis of results of a comparative study under chosen measurement conditions, we conclude that the states of the InAs QDs shift towards the middle of the energy gap if the QDs are capped with a Ga‐rich InGaAs insertion. It explains a red‐shift of the emission wavelength that was found by photoluminescence measurements (PL). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Telecom single‐photon source with horn structure
Authors: Takemoto K. , Hirose S. , Takatsu M. , Yokoyama N. , Sakuma Y. , Usuki T. , Miyazawa T. , Arakawa Y. 
Published: June 2008

AbstractNearly background free 1.5‐μm single‐photon source has been demonstrated using quasiresonant pulsed excitation. We performed a micro‐photoluminescence excitation together with photon‐correlation experiments, and then we compared photon statistics in nonresonant and quasiresonant excitation case. When we tuned the pump laser to the quasiresonant state which is 18.6 meV higher than the ground state excitonic transmission, almost background‐free luminescence was found at 1524.3 nm. The second‐order correlation function at time delay of zero, g(2)(0), was reduced to 0.017 when we carefully estimated noise contributions of after‐pulses and dark counts in InGaAs APD detectors. This result opens up the possibility of promoting high quality single‐photon source at telecommunication wavelength. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Incorporation of N in high N‐content GaAsN films investigated by Raman scattering
Authors: Sanorpim S. , Panpech P. , Vijarnwannaluk S. , Nakajima F. , Kuboya S. , Katayama R. , Onabe K. 
Published: June 2008

AbstractHigh N‐content GaAs1–x Nx films (0 ≤ x ≤ 0.055) grown GaAs (001) substrates by MOVPE were investigated using micro‐Raman spectroscopy. The nitrogen local vibration mode (N‐LVM) which was clearly observed at around 468 ‐ 475 cm‐1 is used as a tool to examine the N incorporation. No change in the local environment of N is observed for the high N‐containing films with N contents up to x = 0.055. The use of 514.5 nm‐line Ar+ laser as the light source gives a linear dependence of the N contents determined by Raman spectroscopy (xRaman) on the N contents determined by the high resolution X‐ray diffraction (xXRD) for xXRD ≤ 0.055, providing a realizable calibration method to determine N content in the high N‐content GaAs1‐x Nx films. On the other hand, the use of longer wavelength (632.8 nm‐line He‐Ne laser) gives a best coincidence for only the lower N contents (x < 0.02). Since, the use of longer wavelength requires the thicker film owing to a thicker optical penetration depth. Thus, in our case, a deviation from the linear behavior for higher N contents, xXRD ≥ 0.02, is not due to the N‐related reasons, but this is the results of the additional Raman scattering intensity of GaAs‐LO from the substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Size control of nanoscaled MnAs dots fabricated on sulfur‐passivated GaAs (001)
Authors: Okabayashi J. , Ueno Y. , Yoshino J. 
Published: June 2008

AbstractWe have investigated the growth conditions of nanoscaled MnAs dots fabricated on sulfur‐terminated GaAs (001) surfaces with regard to the surface coverage and substrate temperature (Ts) during the growth. Scanning tunneling microscopy (STM) images reveal that the size of nanoscaled MnAs dots is controllable with respect to the values of Ts in the range of 200–300 °C. For high Ts values, the sizes of the dots become large and are limited to a diameter and height of 15 and 8 nm, respectively. Further, STM observations indicate the formation of two types of MnAs dots when more than three monolayers are grown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐twin induced structural misalignment in InSb quantum wells
Authors: Mishima T. D. , Edirisooriya M. , Santos M. B. 
Published: June 2008

AbstractStructural misalignments in InSb quantum wells (QWs) caused by a micro‐twin (MT) defect have been investigated by transmission electron microscopy (TEM). Dark field (DF) TEM images with the 002 reflection of the parent region show the misalignment clearly, in spite of their low image intensity. Equations that relate the width of a MT and some dimensions regarding the misalignment are derived. These equations make it possible to deduce the dimensions by [$ \bar 1 $10]‐directional 220 DF‐TEM images which have a higher image intensity than 002 DF‐TEM images. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigations on anisotropic optical properties in semipolar and nonpolar InGaN quantum wells
Authors: Kojima Kazunobu , Kamon Hiroaki , Funato Mitsuru , Kawakami Yoichi 
Published: June 2008

AbstractThe anisotropic band structures and spontaneous emission of the non c plane InGaN/GaN quantum wells (QWs) were computed based on the k·p perturbation theory. Spontaneous emission due to the A valence band is strongly polarized perpendicular to the c axis, while that from the B band has 90º‐rotated polarization, for the crystal angle θ larger than 50°. However, it was found that excited carriers can distribute into both the A and B bands, so that the effective polarization Peff defined by the integrated luminescence intensity is much reduced even for nonpolar InGaN/GaN QWs. Thus, Peff was systematically studied for arbitrary planes. We found that the energy separation between the A and B bands becomes significant and carrier population of the B valence band is suppressed as the In content increases, when Peff approaches unity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaAs emission from GaInP/Er,O‐Co doped GaAs/GaInP laser diodes grown by organometallic vapor phase epitaxy
Authors: Fujii Kei , Hidaka Keiji , Yamamoto Dai , Terai Yoshikazu , Fujiwara Yasufumi 
Published: June 2008

AbstractWe have fabricated GaInP/Er,O‐codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) laser diodes (LDs) by organometallic vapor phase epitaxy (OMVPE) and investigated their lasing characteristics at GaAs band‐edge. Laser emission at the GaAs band‐edge was observed from the DH LDs at room temperature. The threshold current density (Jth) increased by doping of Er. The slope of the Jth against the reciprocal cavity length (1/L) also increased by the Er doping, indicating reduced relaxation time of injected carriers in GaAs:Er,O. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Band warping effect appeared in commensurability oscillations in antidot lattices of a two‐dimensional hole gas
Authors: Kang Ning , Suzuki Kazuya , Abe Eisuke , Hashimoto Yoshiaki , Iye Yasuhiro , Katsumoto Shingo 
Published: June 2008

AbstractWe have confirmed band warping effect of twodimensional holes confined at GaAs/AlGaAs singleheterojunction through classical commensurability resistance oscillations in anti‐dot lattices (ADLs). The oscillations in the triangular ADLs are decomposed into three peaks, two of which are assigned to localized orbits of holes with a lighter effective math (l‐hole), and the other is assigned to that of holes with heavier average effective math (h‐hole). The latter assignment is possible only when the h‐hole band is heavily warped, thus evidencing the warping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the local absorber layer thickness on the performance of ZnO nanorod solar cells
Authors: Belaidi Abdelhak , Dittrich Thomas , Kieven David , Tornow Julian , Schwarzburg Klaus , Lux‐Steiner Martha 
Published: June 2008

AbstractThe local absorber layer thickness (dlocal) of solar cells with extremely thin absorber was changed between 10 nm and 70 nm. As a model system, ZnO nanorod arrays (electron conductor) with fixed internal surface area coated with In2S3 (absorber) and impregnated with CuSCN (transparent hole conductor) were applied. The performance of the small area solar cells depended critically on dlocal. The highest short circuit current density was reached for the lowest dlocal. In contrast, the highest open circuit voltage was obtained for the highest dlocal. A maximum energy conversion efficiency of 3.4% at AM1.5 was achieved. Limiting factors are discussed.(© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new warranty strategy: Combining a renewing free‐replacement warranty with a rebate policy
Authors: Chien Yu‐Hung 
Published: June 2008

AbstractIn this paper, a new warranty policy is proposed and analyzed for repairable products. This policy combines a renewing free‐replacement warranty with a rebate policy. Under this combined policy, the warranty period is partitioned into two intervals. If a product fails during the first interval, the seller replaces the product with a new or repaired product, and the warranty begins anew for the replacement. If a product fails in the second interval, the seller refunds a pre‐specified proportion of the sales price. We derive conditions under which the combined policy is cost‐effective from the perspective of the seller. A numerical example is presented and a sensitivity analysis is performed. Our results imply that reduced demand due to higher prices can be offset with a longer warranty period. Finally, the future extension as well as the practical application of this warranty policy is discussed through an informal survey. Copyright © 2008 John Wiley & Sons, Ltd.
Simultaneous determination of water‐soluble vitamins in selected food matrices by liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Gentili Alessandra , Caretti Fulvia , D'Ascenzo Giuseppe , Marchese Stefano , Perret Daniela , Di Corcia Daniele , Rocca Lucia Mainero 
Published: June 2008

AbstractA rapid, simple and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) with an electrospray ionization (ESI) source for the simultaneous analysis of fourteen water‐soluble vitamins (B1, B2, two B3 vitamers, B5, five B6 vitamers, B8, B9, B12 and C) in various food matrices, i.e. maize flour, green and golden kiwi and tomato pulp, is presented here. Analytes were separated by ion‐suppression reversed‐phase liquid chromatography in less than 10 min and detected in positive ion mode. Sensitivity and specificity of this method allowed two important results to be achieved: (i) limits of detection of the analytes at ng g−1 levels (except for vitamin C); (ii) development of a rapid sample treatment that minimizes analyte exposition to light, air and heat, eliminating any step of extract concentration. Analyte recovery depended on the type of matrix. In particular, recovery of the analytes in maize flour was ≥70%, with the exception of vitamin C, pyridoxal‐5′‐phosphate and vitamin B9 (ca 40%); with tomato pulp, recovery was ≥64%, except for vitamin C (41%); with kiwi, recovery was ≥73%, except for nicotinamide (ca. 30%). Copyright © 2008 John Wiley & Sons, Ltd.
Mass defect profiles of biological matrices and the general applicability of mass defect filtering for metabolite detection
Authors: Zhang Haiying , Zhu Mingshe , Ray Kenneth L. , Ma Li , Zhang Donglu 
Published: June 2008

AbstractRecent examples have demonstrated that the high‐resolution liquid chromatography/mass spectrometry (LC/MS)‐based mass defect filtering (MDF) technique was effective in selectively detecting drug metabolites regardless of their molecular weights or fragmentation patterns. The main objective of the current study was to evaluate the general applicability of MDF for drug metabolite detection in typical biological matrices. Mass defect profiles of commonly used biological matrices including plasma, urine, bile, and feces were obtained using an LTQ FT mass spectrometer and were compared with those of 115 commonly prescribed drugs. The mass defect profiles were presented as two‐dimensional Y‐X plots with the determined mass defects of components on the y‐axis versus the corresponding m/z values on the x‐axis. The mass defect profiles of the matrices appeared to be similar for each type of matrix across species, yet marked differences were apparent between matrices of a given species. The mass defect profiles of components in plasma, bile, and feces showed significant separation from most of the 115 drugs. The mass defect profiles of urine did not show such clean separation from that of the 115 drugs. The results suggest that MDF has a broad applicability for selective detection of drug metabolites in plasma, bile and feces although the selectivity for detecting urinary drug metabolites is not as good as in the other matrices. In addition, the mass defect profiles of the biological matrices allow for prediction of the effectiveness of MDF for certain applications, and for designing specific MDF windows for selective detection of drug metabolites. Copyright © 2008 John Wiley & Sons, Ltd.
Generation and collision‐induced dissociation of ammonium tetrafluoroborate cluster ions
Authors: Dain Ryan P. , Van Stipdonk Michael J. 
Published: June 2008

AbstractSingly and doubly charged cluster ions of ammonium tetrafluoroborate (NH4BF4) with general formula [(NH4BF4)nNH4]+ and [(NH4BF4)m(NH4)2]2+, respectively, were generated by electrospray ionization (ESI) and their fragmentation examined using collision‐induced dissociation (CID) and ion‐trap tandem mass spectrometry. CID of [(NH4BF4)nNH4]+ caused the loss of one or more neutral NH4BF4 units. The n = 2 cluster, [(NH4BF4)2NH4]+, was unique in that it also exhibited a dissociation pathway in which HBF4 was eliminated to create [(NH4BF4)(NH3)NH4]+. Dissociation of [(NH4BF4)m(NH4)2]2+ occurred through two general pathways: (a) ‘fission’ to produce singly charged cluster ions and (b) elimination of one or more neutral NH4BF4 units to leave doubly charged product ions. CID profiles, and measurements of changing precursor and product ion signal intensity as a function of applied collision voltage, were collected for [(NH4BF4)nNH4]+ and compared with those for analogous [(NaBF4)nNa]+ and [(KBF4)nK]+ ions to determine the influence of the cation on the relative stability of cluster ions. In general, the [(NH4BF4)nNH4]+ clusters were found to be easier to dissociate than both the sodium and potassium clusters of comparable size, with [(KBF4)nK]+ ions the most difficult to dissociate. Copyright © 2008 John Wiley & Sons, Ltd.
An improved method for de novo sequencing of arginine‐containing, Nα‐tris(2,4,6‐trimethoxyphenyl)phosphonium‐acetylated peptides
Authors: Kuyama Hiroki , Sonomura Kazuhiro , Shima Keisuke , Nishimura Osamu , Tsunasawa Susumu 
Published: June 2008

AbstractAn improved method for de novo sequencing of arginine‐containing peptides modified with succinimidyloxycarbonylmethyl tris(2,4,6‐trimethoxyphenyl)phosphonium bromide (TMPP‐Ac‐OSu) is reported. A tagging reagent, TMPP‐Ac‐OSu, was introduced to improve the sequence analysis of peptides owing to the simplified fragmentation pattern. However, peptides containing arginine residues did not fragment efficiently even after TMPP‐Ac modification at their N‐termini. This report describes how fragmentation efficiency of TMPP‐Ac‐modified arginine‐containing peptides was significantly improved by modifying the guanidino group on the side chain of arginine with acetylacetone. Copyright © 2008 John Wiley & Sons, Ltd.
Simplified method for microlitre deuterium measurements in water and urine by gas chromatography–high‐temperature conversion–isotope ratio mass spectrometry
Authors: Gucciardi Antonina , Cogo Paola E. , Traldi Umberto , Eaton Simon , Darch Tegan , Simonato Manuela , Ori Carlo , Carnielli Virgilio P. 
Published: June 2008

AbstractDeuterium (2H) in water and urine can be measured by off‐line and, more recently, on‐line techniques using isotope ratio mass spectrometry (IRMS). We describe a new simple on‐line pyrolysis method for the analysis of 2H/1H in water and urine samples by continuous flow IRMS, normally used for 2H/1H measurements in organic compounds. A deactivated column connected the split injector to a high‐temperature conversion reactor (TC HD), and 0.5 µL of sample was injected. Accuracy and precision were determined with Vienna Standard Mean Ocean Water (VSMOW), Standard Light Antarctic Precipitation (SLAP), and Greenland Ice Sheet Precipitation (GISP). The range of linearity was measured with a calibration curve of enriched water from 0 up to 0.1 atom percent excess (APE) (i.e. −72 up to 6323 delta per mil (δD ‰)) with a precision of <5‰ and accuracy ranging between 1 and 55‰. Blinded reanalysis of urine samples by an equilibration device (Gas Bench) and by a dedicated pyrolysis system (TC/EA) was performed and results compared by the Bland‐Altman test. Enrichments ranged between 600 and 2400‰ δDVSMOW with a precision of ±5‰. Urine enrichments described by our method were strongly correlated with values obtained by Gas Bench and TC/EA (p < 0.0001). There was a significant memory effect that was reduced by injecting the sample 15 times and discarding the first 10 injections, together with accurate furnace conditioning and appropriate cleaning of the syringe. Data indicate that the method is accurate, and that it can be used for water and urine deuterium determination when a Gas Bench or TC/EA instrument is not available and the amount of sample is limited. Copyright © 2008 John Wiley & Sons, Ltd.
Maximal stability region of a perturbed nonnegative matrix
Authors: Haut Bertrand , Bastin Georges , Van Dooren Paul 
Published: June 2008

AbstractFor a class of positive matrices A+K with a stable positive nominal part A and a structured positive perturbation part K, we address the problem of finding the largest set of admissible perturbations such that the global matrix remains stable. Theoretical bounds are derived and an algorithm for constructing this set is presented. As an example, this algorithm is applied to the regulation of water flow in open channels. Copyright © 2008 John Wiley & Sons, Ltd.
Stability and robust stability of positive linear Volterra difference equations
Authors: Ngoc Pham Huu Anh , Naito Toshiki , Shin Jong Son , Murakami Satoru 
Published: June 2008

AbstractWe first introduce a class of positive linear Volterra difference equations. Then, we offer explicit criteria for uniform asymptotic stability of positive equations. Furthermore, we get a new Perron–Frobenius theorem for positive linear Volterra difference equations. Finally, we study robust stability of positive equations under structured perturbations and affine perturbations. Two explicit stability bounds with respect to these perturbations are given. Copyright © 2008 John Wiley & Sons, Ltd.
Universality in two‐dimensional enhancement percolation
Authors: Camia Federico 
Published: June 2008

AbstractWe consider a type of dependent percolation introduced in 2, where it is shown that certain “enhancements” of independent (Bernoulli) percolation, called essential, make the percolation critical probability strictly smaller. In this study we first prove that, for two‐dimensional enhancements with a natural monotonicity property, being essential is also a necessary condition to shift the critical point. We then show that (some) critical exponents and the scaling limit of crossing probabilities of a two‐dimensional percolation process are unchanged if the process is subjected to a monotonic enhancement that is not essential. This proves a form of universality for all dependent percolation models obtained via a monotonic enhancement (of Bernoulli percolation) that does not shift the critical point. For the case of site percolation on the triangular lattice, we also prove a stronger form of universality by showing that the full scaling limit 12, 13 is not affected by any monotonic enhancement that does not shift the critical point. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008