bluuebunny/crossref_metadata_2025_split huggingface dataset:
The future of PV industry and SG‐Si materials
Authors: Zhao Yuwen 
Published: January 2009

AbstractThe future demand of solar grade silicon (SG‐Si) materials is discussed from PV Industry future trend in this paper. The production of ultra‐purity silicon (UP‐Si) materials (including EG‐Si and SG‐Si) will be a big industry and will have a great contribution to world society with high‐speed development of PV industry. For demand of future, the purity issue of SG‐Si is discussed from requirement of solar cell performance and operation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge storage and light emission properties of three dimension controllable Si nanostructures
Authors: Chen Kunji , Huang Jian , Ma Zhongyuan , Wang Xiang , Yao Yao , Wang Jiumin , Li Wei , Xu Jun , Huang Xinfan 
Published: January 2009

AbstractSize controllable nanocrystalline silicon (nc‐Si) materials show novel electrical and optical characteristics of silicon quantum dots. Based on laser induced constrained crystallization principle, the one‐/two‐/three‐dimension (1D, 2D and 3D) ordered controllable nc‐Si array have been successfully obtained by using phase‐shifting grating mask combine with multilayer structures. The tunable photoluminescence (PL) and electro‐luminescence (EL) from this kind of nc‐Si films have been observed. The collective single‐electron resonant tunneling and charge storage in the uniform nc‐Si single layer have been studied by using I‐V and the C‐V measurement at room temperature. The double level charge storage in stacked nc‐Si layer based metal‐insulator‐semiconductor (MIS) structure has been demonstrated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impurity engineering for germanium‐doped Czochralski silicon wafer used for ultra large scale integrated circuit
Authors: Chen Jiahe , Yang Deren 
Published: January 2009

AbstractInternal gettering (IG) technology has been challenged by both the reduction of thermal budget during device fabrication and the enlargement of wafer diameter. Improving the properties of Czochralski (Cz) silicon wafers by intentional impurity doping, the so‐called ‘impurity engineering (IE)’, is defined. Germanium has been found to be one of the important impurities for improving the internal gettering effect in Cz silicon wafer. In this paper, the investigations on IE involved with the conventional furnace anneal based denudation processing for germanium‐doped Cz silicon wafer are reviewed. Meanwhile, the potential mechanisms of germanium effects for the IE of Cz silicon wafer are also interpreted based on the experimental facts. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light emission from ion‐implanted silicon
Authors: Sun J. M. , Helm M. , Skorupa W. , Schmidt B. , Mücklich A. 
Published: January 2009

AbstractSi pn junction light emitting devices (LEDs) with dislocations were prepared by means of high‐dose B+ and Si+ self‐ion implantation. The Si LEDs with dislocations created by high‐dose boron implantation emit much stronger band edge electroluminescence (EL) compared to the ones with dislocations created by Si+ implantation. At 12 K, the EL peaks from the bound excitons around the dislocations created by high‐dose boron implantation show strong blue shift with increasing the injection current, this suggests that the dislocations are decorated with locally heavy p‐type doping, which originated from boron gettering at the dislocations. The thermal dissociation of the bound excitons leads to an anomalous increase of the band edge electroluminescence with increasing temperature. Finally, efficient silicon LEDs with interdigital micro p‐type doping arrays were demonstrated with a wall‐plug external quantum efficiency of 0.15% by implementing the band gap engineering concept from the modulation doping technology. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The migration of gold on large diameter silicon nanowires in oxygenous system
Authors: Wan Yuting , Wang Yewu , Chen Bo , Fang Yanjun , Sha Jian 
Published: January 2009

AbstractSilicon nanowires (SiNWs) of about 200‐500 nm in diameter with branch morphology were fabricated by one step in oxygenous chemical vapour deposition (CVD) system. The catalyst Au particles on branches came from the migration of Au on the tip of trunk. We speculate that the migration of gold is due to the large diameter of gold particles. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐resolution analytical electron microscopy of silicon nanostructures
Authors: Schade Martin , Geyer Nadine , Fuhrmann Bodo , Heyroth Frank , Werner Peter , Leipner Hartmut S. 
Published: January 2009

AbstractWe report on both the fabrication of hexagonally ordered, vertically aligned silicon nanowires (SiNW) and their characterization by means of analytical transmission electron microscopy. Combining colloidal lithography, plasma etching, and catalytic wet etching, SiNW with well defined diameter, length, and density can be obtained. For this purpose hexagonally closed packed monolayers of monodisperse polystyrene particles are transferred into non‐closed packed particle arrays. These arrays are used as a mask for silver deposition by thermal evaporation. After the lift‐off of the spheres, the silver layer serves as a catalyst for the wet‐etching process in an H2O2/HF solution. In this way, arrays of SiNW of sub‐50 nm diameter with an aspect ratio of up to 10 could be fabricated. Scanning electron microscopy as well as scanning transmission electron microscopy have been applied in order to investigate the morphology, the internal structure and the composition of the catalytically etched SiNW. The analysis yielded a single crystalline, porous structure composed of crystalline silicon and SiOx with x ≤ 2. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synchrotron microscopy and spectroscopy for analysis of crystal defects in silicon
Authors: Seifert Winfried , Vyvenko Oleg F. , Arguirov Tzanimir , Erko Alexei , Kittler Martin , Rudolf Carsten , Salome Murielle , Trushin Maxim , Zizak Ivo 
Published: January 2009

AbstractThe paper discusses the synchrotron‐based microprobe techniques XBIC (X‐ray beam induced current), μ‐XRF (X‐ray fluorescence microscopy) and μ‐XAS (X‐ray absorption microspectroscopy) and their application for studying electrical activity of defects and precipitation of transition metals in Si materials. Investigations were performed on samples of block‐cast multicrystalline Si and on model samples cut from a bonded monocrystalline wafer. To analyze the precipitation sites, Ni, Cu and Fe were introduced intentionally into the samples. The detected precipitates were found to consist of silicides. Evidence for metal precipitates was also found in virtually uncontaminated as‐grown block‐cast Si. Besides Ni precipitates detected at a recombination active grain boundary, particles containing one or several metals (Cu, Fe, Ti, V) were observed. Unexpectedly, these particles seem to exhibit low only recombination activity. Further studies are necessary to identify their nature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optoelectronic application of Si/Ge heterostructures
Authors: Kasper E. , Oehme M. 
Published: January 2009

AbstractSilicon germanium heterostructures extend considerably the optoelectronic performance of silicon based systems. Together with small width waveguides on SOI substrates a variety of attractive applications can be tackled as monolithic integrated systems. Examples are on‐chip clock distribution, fiber to the home front ends and infrared arrays for night vision. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelectrochemical roughening of p‐GaN for light extraction from GaN/InGaN light emitting diodes
Authors: Tamboli Adele C. , McGroddy Kelly C. , Hu Evelyn L. 
Published: January 2009

AbstractA method for photoelectrochemical (PEC) etching of Ga‐face, p ‐type GaN is presented using GaN/InGaN heterostructures. This technique, which does not require any special epitaxial structure, flip chip bonding, or complicated processing, is used to roughen p ‐side‐up lightemitting diodes (LEDs) to increase extraction efficiency. The extraction efficiency is increased by 20 ± 5% for roughened LEDs compared to nearby unetched LEDs, without any effect on the electrical properties of the devices. This is the first report of rapid, external‐bias free PEC etching of p ‐type GaN, which could have broad applications to low‐damage selective etching for a variety of electronic and optical devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Off‐state breakdown in InAlN/AlN/GaN high electron mobility transistors
Authors: Kuzmik J. , Pozzovivo G. , Carlin J.‐F. , Gonschorek M. , Feltin E. , Grandjean N. , Strasser G. , Pogany D. , Gornik E. 
Published: January 2009

AbstractUnpassivated InAlN/AlN/GaN high electron mobility transistors off‐state breakdown is analyzed for different gate‐to‐drain distances. The breakdown voltage linearly increases with the gate to drain distance reaching 350 V for a 10 μm contact separation; the sub‐threshold leakage current is < 10–5 A/mm. Similar breakdown voltages and leakage current are obtained on GaN buffer for two Ohmic contacts if their distance is the same. It is suggested that the breakdown is governed by injection/avalanche processes in the GaN buffer layer and is basically not affected by InAlN barrier. Our conclusions are further supported by measuring all currents in the three‐terminal configuration of the transistors before and during the breakdown and by using a drain current injection technique. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN‐based deep green light emitting diodes on silicon‐on‐insulator substrates
Authors: Tripathy S. , Dadgar A. , Zang K. Y. , Lin V. K. X. , Liu Y. C. , Teo S. L. , Yong A. M. , Soh C. B. , Chua S. J. , Bläsing J. , Christen J. , Krost A. 
Published: January 2009

AbstractWe have demonstrated deep green InGaN/GaN light emitting diodes (LEDs) on 100 nm thick (111)‐oriented silicon‐on‐insulator (SOI) substrate. The LED structures are grown by metalorganic chemical vapour deposition. High‐resolution X‐ray diffraction and transmission electron microscopy have been used to characterize the structural quality of the LED layers. The room temperature electroluminescence (EL) spectrum from these LEDs is dominated by multiple interference peaks associated with the reflectivity changes at the bottom Si/SiO2 interfaces beneath AlN buffer. The spectral intensity of the LEDs in the deep green region is higher due to the larger substrate reflectance at longer wavelengths. A greater modulation in the spectral fringes in the longer wavelength regions is due to the presence of Fabry‐Perot modes. Such InGaN/GaN light emitting structures on reflective SOI may be useful for the realization of phosphor‐free white LEDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of diffusion and thermal stability of fluorine ions in GaN by Time‐of‐Flight Secondary Ion Mass Spectroscopy
Authors: Wang Maojun , Yuan Li , Xu Fujun , Shen Bo , Chen Kevin J. 
Published: January 2009

AbstractThe diffusion properties of fluorine ions in GaN are investigated by means of Time‐of‐Flight secondary ion mass spectroscopy. Instead of incorporating fluorine ions close to the sample surface by plasma, fluorine ion implantation with an energy of 180 keV is utilized to implant fluorine ions deep into the GaN bulk, preventing the surface effects from affecting the data analysis. It is found that the diffusion of fluorine‐ions in GaN is a dynamic process, featuring a two‐step process. A defect‐assisted diffusion model is proposed to account for the experimental observations. Fluorine ions tend to occupy Ga vacancies induced by fluorine ion implantation and diffuse to vacancy rich regions. The fluorine ions become stable after continuous vacancy chains are significantly reduced or removed by thermal annealing. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of nitridation on structural and optical properties of MOVPE‐grown m‐plane GaN layers on LiAlO2
Authors: Mauder C. , Rahimzadeh Khoshroo L. , Behmenburg H. , Reuters B. , Bösing M. , Rzheutskii M. V. , Lutsenko E. V. , Yablonskii G. P. , Woitok J. F. , Chou M. M. C. , Heuken M. , Kalisch H. , Jansen R. H. 
Published: January 2009

AbstractIn this paper, we investigate the influence of the nitridation of LiAlO2 substrates on the growth of m‐plane (1‐100) GaN layers by metal‐organic vapour phase epitaxy (MOVPE). Before thin film deposition, we performed an in‐situ substrate pretreatment by exposing the wafer to NH3 for different times between no pretreatment and 300 s. The properties of subsequently grown layers show a significant dependency on this nitridation step. We find that this procedure is essential for obtaining pure m‐plane GaN films and has a beneficial effect on the X‐ray rocking curve (XRC) full width at half maximum (FWHM) value, which decreases by almost two orders of magnitude. Deposited layers with NH3 pretreatment also exhibit much smoother surfaces with a reduction of the root mean square (RMS) roughness value from ∼20 to ∼6 nm. Additionally, the nitridation greatly increases the GaN band edge emission intensity in room temperature (RT) photoluminescence (PL) spectroscopy. Furthermore, we compare the sensitivity of the substrate against water for uncoated LiAlO2 wafers with and without nitridation process. While the untreated surface shows a clear roughening when dipped into de‐ionized (DI) water for 5 min, we can see no significant impact on the nitridated substrate surface. This indicates a change in surface composition which protects the sensitive substrate surface and provides good conditions for the nucleation of high‐quality m‐plane GaN films. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlN/AlGaN/GaN/AlGaN multilayer heterostructures with quantum well channel on heat conducting substrates for power microwave transistors
Authors: Krasovitskiy Dmitry , Alexeev Alexey , Byrnaz Anton , Kokin Sergey , Pavlenko Maxim , Petrov Stanislav , Pogorelsky Michael , Pogorelsky Yury , Sokolov Igor , Sokolov Michael , Shkurko Alexey , Chaly Victor 
Published: January 2009

AbstractMolecular beam epitaxy using ammonia as a nitrogen source is applied to obtain III‐nitride multilayer heterostructures having high structural quality and low dislocation density. To provide strong carrier confinement in two‐dimensional electron gas for collapse‐free transistor operation, GaN quantum well as thin as 5 nm was formed between AlGaN barrier layers of various Al content, keeping high sheet conductivity in 280‐350 Ohm/square range. Due to rather thick AlN “template” grown at extremely high (up to 1200 °C) substrate temperatures directly in the same growth run prior to the growth of heterostructure, technology developed on sapphire is easily transferred to alternative substrates, for example AlN/SiC or Si. In contrast to sapphire, where noticeable drop of transistor saturation current at drain voltages higher than 5‐10 V is usually observed, heat conducting substrates allow to avoid this negative thermal effect and no drop is observed at drain voltages up to 20 V and even higher. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bulk GaN crystals and wafers grown by HVPE without intentional doping
Authors: Łucznik Bolesław , Pastuszka Bogdan , Weyher Jan L. , Kamler Grzegorz , Grzegory Izabella , Porowski Sylwester 
Published: January 2009

AbstractIn this work, bulk crystals of GaN were grown in multiple HVPE runs in order to get about 5 mm thick samples. Then the crystals were sliced in both polar and non‐polar orientations. Dominant morphological defects in GaN bulk crystals grown by HVPE on (0001) oriented substrates are polygonal pits of various depths. Since the pits are composed of semi‐polar surfaces, it is possible to recover their formation and growth history by optical microscopy and photochemical etching sensitive to the fluctuations in concentration of point defects. For example dark triangles on the non‐polar slice in the figure are traces of pits moving along growth direction thus leaving highly oxygen doped trace underneath. Analysis of distribution, properties and origin of these defects, based on measurements of polar and non‐polar slices of the bulk crystals is presented. One of reasons for the pits formation are inversion domains generated at different stages of the HVPE growth. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical polarisation anisotropy in a ‐plane GaN/AlGaN multiple quantum well structures
Authors: Badcock Tom J. , Dawson Philip , Kappers Menno J. , McAleese Clifford , Hollander Jonathan L. , Johnston Carol F. , Sridhara Rao Duggi V. , Sanchez Ana M. , Humphreys Colin J. 
Published: January 2009

AbstractIn this paper we report on the optical properties of a series of a ‐plane GaN/AlGaN multiple quantum well structures of varying well width. The low temperature photoluminescence spectrum of each structure is characterised by two distinct emission bands, both of which shift to higher energy with decreasing well thickness. The origin of the lower energy emission band is attributed to the recombination of carriers trapped in regions of the quantum wells intersected by basal plane stacking faults. The higher energy feature is assigned to localised exciton recombination at well width fluctuations. We have used photoluminescence excitation spectroscopy to reveal details of the bandstructure of the quantum wells. Excitation with unpolarised light resulted in the observation of exciton transitions associated with the n = 1 and n = 2 electron sub‐bands. For linearly polarised (E⊥c and E‖c) excitation, both the transitions observed with unpolarised light were shown to consist of overlapping transitions involving heavy and light hole like valence subbands. Their observed polarisation anisotropy was attributed to anisotropic biaxial compressive strain in the GaN film. As well as the exciton transitions we were also able to resolve well defined continuum edges in some of the excitation spectra. This enabled us to estimate the exciton binding energy of the n = 1 heavy and light hole states for quantum wells of differing width. Values were found to lie in the range of 38 to 76 ±5 meV. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Therapeutic advantages of medicinal herbs fermented with Lactobacillus plantarum, in topical application and its activities on atopic dermatitis
Authors: Joo Seong Soo , Won Tae Joon , Nam Sang Yoon , Kim Yun‐Bae , Lee Young Chul , Park So‐Yong , Park Hee Yong , Hwang Kwang Woo , Lee Do Ik 
Published: January 2009

AbstractThe use of herbal medicines in the therapeutic treatment of atopic dermatitis (AD) has been suggested recently. The present study examined whether selected herbal extracts fermented in Lactobacillus plantarum (FHE) possessed anti‐AD properties. In addition, the study assessed the increased bioavailability of these herbal extracts both in vitro and in vivo. The data from these experiments revealed that FHE inhibited the proliferation of splenic T and B cells in a dose‐dependent manner, when activated with their mitogens. Moreover, the expression of Th1/Th2 mRNA cytokines (IL‐2, IL‐4, IL‐5, IL‐13) from mouse splenocytes was inhibited severely as was cyclosporine A. Furthermore, the release of β‐hexosaminidase in RBL‐2H3 mast cells was suppressed significantly. FHE also reduced the plasma level of IgE in dust mite extract‐induced AD‐like NC/Nga mice. More dramatic results were found in the histological changes, which were observed by hematoxylin–eosin and toluidine blue staining, as well as in the macroscopic features on dorsal lesions of AD‐like NC/Nga mice. In conclusion, the results presented in this study suggest that FHE may have therapeutic advantages for the treatment of AD due to its increased immune‐suppressive and increased absorptive effects, which were fortified by L. plantarum fermentation. Copyright © 2009 John Wiley & Sons, Ltd.
Maximum‐Likelihood Estimation of Predictive Uncertainty in Probabilistic QSAR Modeling
Authors: Pery Alexandre , Henegar Adina , Mombelli Enrico 
Published: January 2009

AbstractQuantitative Structure–Activity Relationships (QSAR) models routinely predict biological activities of interest and the resulting predictions are meaningful only if their uncertainty is properly characterized. Consequently, the availability of a methodology allowing the estimation of predictive uncertainty for QSAR predictions is an issue of practical relevance both for scientific research and for regulatory purposes. In this paper, we present a novel statistical methodology based on maximum likelihood estimation that enables the QSAR prediction of biological activities and the probabilistic assessment of the uncertainty attached to individual predictions. In the formulation of the methodology, chemicals are positioned in a descriptor hyperspace whose coordinates are defined by a set of orthogonal axis such as the principal components determined by Partial Least Squares (PLS) regressions. Each training set chemical contributes in predicting the probability for the query chemical to be active and such a contribution is weighted with respect to the Euclidean distance separating the two chemicals. This study explains how uncertainty can be probabilistically assessed during QSAR modeling of molecular databases and compares the performance of the predictive methodology to published data.
Density fitting for derivatives of Coulomb integrals in ab initio calculations using mixed Gaussian and plane‐wave basis
Authors: Čársky Petr 
Published: January 2009

AbstractThis article presents an efficient way for evaluation of Coulomb integrals of the type (k1 (1)k2 (1)|g1 (2)g2 (2)) and their derivatives with respect to nuclear coordinates by means of density fitting. Symbols k1 andk2 stand for plane‐wave functions and g1 and g2 for gaussians. The study was undertaken with the objective to accelerate electronic structure and electron scattering calculations in which a mixed Gaussian and plane‐wave basis set is used. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical study on the interlay of hydrogen bonds in the trimers involving HCN and water
Authors: Li Qingzhong , Wang Xilin , Cheng Jianbo , Li Wenzuo , Gong Baoan , Sun Jiazhong 
Published: January 2009

AbstractIn this study, the hydration of hydrogen cyanide (HCN) has been investigated by means of quantum chemical ab initio calculations at the MP2/6‐311++G(3df,2p) level. Various HCN· · ·( H2O)2and (HCN)2· · ·H2O complexes were optimized. Geometrics and energetics in these complexes have been analyzed. The hydration of the H atom leads to an elongation of the NC and CH bonds, whereas the hydration of the N atom results in a contraction of the NC bond and a little elongation of the CH bond. The interaction energy between each molecule pair in the trimers (except in HCNH2OH2O trimer) is increased relative to that in the respective dimer. The cooperativity of hydrogen bond in HCNH2OH2O trimer plays a negative contribution to the total interaction energy of the complex, whereas that in the other trimers is a positive contribution. Geometry and energy in H2OH2OOHCNH2O tetramer have also been analyzed. The binding energies in the trimers and tetramer have been studied by means of many‐body interaction analysis. The mechanism of HCN hydration was suggested. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009