bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison between extended microtunnels along different crystal orientations in GaN
Authors: Wu Pei‐Lun , Huang Hsin‐Hsiung , Zeng Hung‐Yu , Liu Po‐Chun , Lai Chih‐Ming , Tsay Jeng‐Dar , Lee Wei‐I 
Published: April 2008

AbstractTriangular prism‐like extended microtunnels (EMTs) can be easily formed in specially designed epitaxial lateral overgrowth GaN thick films by selective wet chemical etching in molten potassium hydroxide (KOH). In this study, extended microtunnels along the 〈1$ \bar 1 $00〉 and the 〈1$ \bar 2 $00〉 directions were fabricated and compared. If tunnels along the 〈1$ \bar 1 $00〉 direction, the {11$ {\bar 2} {\bar 2} $} planes would be the etch stop plane. While the tunnels along 〈1$ \bar 2 $00〉 direction, the etch stop plane would become to {10$ {\bar 1} {\bar 1} $} planes. The activation energies of wet chemical etch for the {11$ {\bar 2} {\bar 2} $} planes and the {10$ {\bar 1} {\bar 1} $} planes were determined to be 23.6 kcal/mol (1.02 eV) and 22.8 kcal/mol (0.99 eV) using Arrhenius plot. On the other hand, the etching depths of the tunnels along the 〈1$ \bar 1 $00〉 direction were more than twice the depths of the tunnels along the 〈1$ \bar 2 $00〉 direction during the same etching time. The highest etch rate of the tunnels along the axial direction can reach 1000 μm/hr in 〈1$ \bar 1 $00〉 direction, which is believed to be the highest etch rate of GaN ever reported. Additional crystal facet of m‐plane in GaN was also observed in the sample with extended microtunnels along the 〈1$ \bar 2 $00〉 direction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and Raman spectroscopy of MBE‐grown InN nanocolumns
Authors: Segura‐Ruiz J. , Garro N. , Cantarero A. , Denker C. , Werner F. , Malindretos J. , Rizzi A. 
Published: April 2008

AbstractInN nanocolumns grown under different conditions by plasma‐assisted molecular beam epitaxy on p‐Si (111) substrates are studied by micro‐Raman and photoluminescence (PL) spectroscopies. The nanocolumns are free of strain and have an improved crystal quality as shown by the frequency and linewidth of the nonpolar E2h mode. Uncoupled polar modes coexist with a couple LO phonon‐plasmon mode and are sensitive to the nanocolumn morphology. Variations in the growth conditions also modify the PL spectra significantly. An increase in the PL energy also involves a reduction of the integrated intensity and an increase of the PL linewidth. This overall phenomenology highlights the role of the surface accumulation layer in these nanostructures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of metallic surface coverage on material quality in III‐nitride MOVPE
Authors: Kondratyev A. V. , Talalaev R. A. , Segal A. S. , Yakovlev E. V. , Lundin W. V. , Zavarin E. E. , Sinitsyn M. A. , Tsatsulnikov A. F. , Nikolaev A.E. 
Published: April 2008

AbstractPinholes and pits are well known types of defects characteristic for nitride growth by MOVPE. This paper reports on studies of the correlation between the defect appearance and MOVPE growth conditions and discusses the ways to improve the material quality. A decrease of the ammonia flow at a constant total flow during MOVPE of GaN in a hydrogen‐ammonia atmosphere at moderate temperatures (750‐900 °C) has revealed the overgrowth of pinholes up to their almost complete disappearance. The same effect was observed by the addition of a certain amount of trimethyindium to the gas phase. In both cases the improvement in morphology was associated with an accumulation of metallic (Ga and In, respectively) atoms in the adsorption layer at the growing surface. This conclusion was supported by surface kinetics model computations. The model suggests possible strategies for the growth of pinhole‐free layers in various device structures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical properties of indium‐rich InGaN islands
Authors: Tsai Wen‐Che , Lin Hsuan , Ke Wen‐Chen , Chang Wen‐Hao , Chou Wu‐Ching , Chen Wei‐Kuo , Lee Ming‐Chih 
Published: April 2008

AbstractIndium‐rich Inx Ga1‐x N islands (x ≥ 0.87) grown by metalorganic chemical vapor deposition at growth temperatures ranging from 550‐750 °C were investigated. With the increasing growth temperature, the InGaN dot size increases while the dot density decreases due to the enhanced surface migration of In/Ga adatoms at elevated temperatures. In addition, the composition of InGaN islands was also found to be varied with the growth temperature. At lower growth temperatures, a higher Ga content can be achieved due to the relatively lower migration ability of Ga adatoms. At higher growth temperatures, the deposited InGaN material tend to decompose into In‐rich islands and a thin Ga‐rich layer. Photoluminescence investigations show that these In‐rich islands exhibit a near‐infrared emission band. For samples grown at higher temperatures, a visible emission band was also observed. The visible emission band may arise from defect bands introduced during the formation of Ga‐rich InGaN layer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐organized growth of InN‐nanocolumns on p‐Si(111) by MBE
Authors: Denker Christian , Malindretos Joerg , Werner Florian , Limbach Friederich , Schuhmann Henning , Niermann Tore , Seibt Michael , Rizzi Angela 
Published: April 2008

AbstractInN‐nanocolumns are an attractive system for light harvesting applications. To understand the mechanism of self organized growth of nanocolumns in plasma assisted MBE, InN samples were produced under various conditions on p‐Si(111). Depending on the growth parameters different growth regimes for nanocolumns were identified according to their final shape. High‐resolution TEM pictures show a very good crystal quality. This is also confirmed by Raman and PL measurements. Nanocolumns with diameters of 20‐200 nm and lengths of up to 2 mm were produced. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of a novel hyperspectral detector using the III‐nitrides
Authors: Tripathi N. , Bell L. D. , Grandusky J. R. , Jindal V. , Shahedipour‐Sandvik F. 
Published: April 2008

AbstractWe report on the growth and characterization of a novel, III‐nitrides based, tunable hyperspectral photodetector. The proposed device structure consists of AlxGa1–xN multilayer heterostructure with Al composition of 0 < x <1 grown on a GaN/sapphire template. The AlxGa1–xN heterostructure forms a stepped triangular profile potential barrier whereby the height of the potential barrier can be tuned by varying the applied voltage. Height of the potential barrier determines the threshold energy of the photoemission current over the potential barrier and hence determines the detection wavelength of the device. Device structures with different AlGaN layer thicknesses are evaluated to understand the dependence of the dark current and the quantum efficiency of the device on the thickness of the barrier structure. Internal photoemission (IPE) measurements have been carried out to measure the potential barrier faced by the photoexcited carriers. A reduction in potential barrier by 0.65 eV is observed over an applied voltage of 1.3 V, confirming the tunability of detection wavelength. Current‐voltage (I‐V) measurements and atomic force microscopy (AFM) have been used to study and improve the device performance. IPE, I‐V and AFM results are presented along with a discussion on the principle of device operation, detection wavelength tunability range and device structure optimization parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective area heteroepitaxy of low dimensional a ‐plane and c ‐plane InGaN nanostructures using pulsed MOCVD
Authors: Jindal V. , Tripathi N. , Tungare M. , Paschos O. , Haldar P. , Shahedipour‐Sandvik F. 
Published: April 2008

AbstractHigh density a ‐plane and c ‐plane InGaN nanostructures have been developed by nanoscale selective area epitaxial growth using pulsed MOCVD. SiO2 was used as a mask with nanopatterning through an anodic aluminum oxide template. The lateral dimensions of the pattern were controlled and varied from 30 nm to 180 nm by changing the anodization voltage and the electrolyte. Different substrates such as a ‐plane GaN on r ‐plane sapphire, r ‐plane sapphire and c ‐plane sapphire were used to develop InGaN nanostructures in a ‐ and c ‐ crystallographic directions respectively. Under identical growth conditions, InGaN nanostructures of various shapes were obtained on different substrates with differences in emission wavelength. The shape of the nanostructures on different substrates is discussed with respect to the stability and growth rates of various planes. However, the difference in emission wavelength is attributed to the In incorporation in the nanostructures. The optical properties of the nanostructures were studied by photoluminescence (PL) spectroscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation into the use of molecular hydrogen on the growth of gallium nitride via metal‐organic molecular beam epitaxy
Authors: Billingsley Daniel , Pritchett David , Henderson Walter , Carver Alexander G. , Burnham Shawn D. , Doolittle W. Alan 
Published: April 2008

AbstractMolecular hydrogen (H2) has been investigated as a means to improve ammonia nitridation efficiency and attempts to reduce carbon contamination in ammonia‐based metal‐organic molecular beam epitaxy (MOMBE). A 30% improvement in crystalline quality, inferred from XRD, as well as an increase in subsequent GaN bulk growth rate was observed when bare sapphire was subject to H2 annealing before nitridation. However, the use of H2 during GaN homoepitaxy on GaN templates resulted in increased carbon contamination and decreased growth rate of GaN. The results demonstrate promise and proper uses of H2 during GaN growth under certain conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence study of hexagonal InN/InGaN quantum well structures grown on 3C‐SiC (001) substrates by molecular beam epitaxy
Authors: Hirano S. , Inoue T. , Shikata G. , Orihara M. , Hijikata Y. , Yaguchi H. , Yoshida S. , Hirabayashi Y. 
Published: April 2008

AbstractWe have studied photoluminescence from hexagonal InN/InGaN multiple quantum well structures grown on 3C‐SiC (001) substrates with an InGaN underlayer by plasma assisted molecular beam epitaxy. We have observed photoluminescence spectra of InN/InGaN MQWs with various well widths. The photoluminescence peak related to quantum wells was clearly observed even at room temperature and found to shift to higher energies with decreasing well width due to the quantum confinement effect. We also discuss the effect of the built‐in electric fields on the PL peak energy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Domain wall thickness variations of ferroelectric BaMgF4 single crystals in the tip fields of an atomic force microscope
Authors: Zeng H. R. , Shimamura K. , Villora E. A. G. , Takekawa S. , Kitamura K. , Li G. R. , Yin Q. R. 
Published: April 2008

AbstractThe ferroelectric domain wall thickness of a fluoride BaMgF4 single crystal was investigated by piezoresponse force microscopy. It was found that the domain wall thickness shows a strong spatial variation in the as‐grown crystal and the polarization reversal process. The original wall thickness is greater (about two to seven times) than that switched by the tip fields of the atomic force microscope. A significantly narrower domain wall was obtained in the higher tip‐field. The trapped defects at the domain wall play an important role in the spatial variation of the polarization width of 180° domain wall in the BaMgF4 single crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrodynamic simulation of the operational management of a proposed flood emergency storage area at the Middle Elbe River
Authors: Förster Saskia , Chatterjee Chandranath , Bronstert Axel 
Published: April 2008

AbstractEmergency storage areas can be an effective structural flood protection measure. By their controlled flooding the risk of inundation for downstream areas with higher vulnerability can be reduced.In the present study, the flooding and emptying process of a proposed storage area at the Middle Elbe River is simulated. The storage area has a maximum capacity of 40 million m3 and is divided into two polder basins. It is designed for the attenuation of extreme floods of 100 years or more return period.A one‐dimensional hydrodynamic model is set up for a 20 km reach of the Elbe River, wherein the storage area is schematised by two storage cells each representing one polder basin. Flow between the storage cells and the Elbe River is controlled by adjustable gates, which operate based on the pre‐defined conditions.Four flood scenarios which differ in flood magnitude and hydrograph shape are simulated. The scenarios are derived from analyses of a 70 years discharge record. Furthermore, for each flood scenario two gate control strategies are investigated.The results show that during large floods the utilization of the storage area with controlled gate operations significantly reduces the Elbe River peak discharges. However, the magnitude of the attenuation depends on the steepness of the flood hydrograph and the applied control strategy with well‐timed gate operations. Copyright © 2008 John Wiley & Sons, Ltd.
Trend analysis of water quality in some rivers with different degrees of development within the São Paulo State, Brazil
Authors: Groppo Juliano Daniel , de Moraes Jorge Marcos , Beduschi Carlos Eduardo , Genovez Abel Maia , Martinelli Luiz Antonio 
Published: April 2008

AbstractTime series of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate, total phosphorus, chloride, ammonia and faecal coliforms (FC), monitored by CETESB (‘Companhia de Tecnologia de Saneamento Ambiental’), in the period from 1979 to 2001, were analysed in seven river basins located in the São Paulo State, one of the most developed regions in Brazil. The selected rivers, Piracicaba, Mogi‐Guaçu, Turvo Grande, Peixe, Aguapeí, São José dos Dourados and Alto Paranapanema have different degrees of development concerning industrial, agricultural and population growth. Trend analysis methodology was based on graphical exploratory analysis followed by confirmation through statistical tests. Results showed impoverishment of the water quality conditions in most of the studied basins, represented by the positive trends of the parameters (BOD, nitrogens, total phosphorus, clorate and FC) and negative trend of the parameter (DO). Among the analysed basins, the Piracicaba River is the most severely affected with higher variations in the magnitude followed by the basins of the Mogi‐Guaçu, Turvo Grande, Peixe and Aguapeí Rivers. On the other hand, the Alto Paranapanema and São José dos Dourados basins are the least affected. Copyright © 2008 John Wiley & Sons, Ltd.
Observation of localized optical near‐field generated by submicron two‐hole structure for novel SNOM probe
Authors: Oshikane Yasushi , Hara Seiji , Matsuda Takuya , Inoue Haruyuki , Nakano Motohiro , Kataoka Toshihiko 
Published: April 2008

AbstractA novel concept for the fabrication of a submicrometer‐structured probe tip for application in scanning near‐field optical microscopy (SNOM) based on a metalized optical fiber and a focused ion beam (FIB) milling is presented and investigated experimentally. This concept has the potential to enable a novel SNOM probe having a reproducible characteristic in the generation of intense and highly localized optical near‐field at the probe tip. As the simplest case designed by the boundary element method (BEM), a fine structure, which sandwiches a small projecting portion between a pair of 100‐nm2 holes, was fabricated by FIB in a 200‐nm silver thin film on a flattened end face of the single‐mode optical fiber. This unique structure was backlit by light from an Ar+ ion laser with a wavelength of 514.5 nm, which passes along the fiber core, and combined optical and topographical measurements for detecting the localized optical near‐field around the holes. A sample scan was performed using a modified SNOM system employing a dielectric spherical probe of 500 nm in diameter, which was illuminated by the evanescent field arising from the total internal reflection of He‐Ne laser light with a wavelength of 632.8 nm. As a result, a small dimple corresponding to the two‐hole structure was observed in the topographic image and a bright spot having high locational correlation with the dimple was simultaneously recorded in the optical image. Further study is required to determine the dependence of the optical near‐field intensity and its localization on the submicrometer two‐hole structure. Copyright © 2008 John Wiley & Sons, Ltd.
A systemic framework for case‐based classroom experiential learning
Authors: Georgiou I. , Zahn C. , Meira B. J. 
Published: April 2008

AbstractThis paper presents the two general types of cases designed for use in the classroom. It discusses how each type implies a particular instructional approach, and outlines the learning consequences of each approach. In doing so, it shows how each instructional approach on its own proves to be educationally deficient. The paper then draws from a systems thinking epistemology to argue that when the two instructional approaches are combined, emergent educational benefits arise. A critical appreciation of Kolb's learning cycle is simultaneously offered. The paper then offers a systemic framework for case‐based classroom experiential learning. The paper concludes with a critical review of this framework which can serve to guide instructors. Copyright © 2008 John Wiley & Sons, Ltd.
Can outstanding performance also be long‐standing?
Authors: Xardel Dominique , Schulz Annegret 
Published: April 2008

AbstractBest practices in the business world are often identified by benchmarking in relation to products and the processes by which those products are created and delivered. This can take place inside a specific industry, but also in other industries and different countries. There, the main challenge for global firms is to decide how and how far to adapt those practices to the local environment, which is, in most cases, very different from their domestic markets.This article examines the performance of selected companies from various industries that have, in recent years, successfully developed and implemented new business concepts and new business processes in both their domestic and global markets while implementing their global strategy. The article also seeks to identify and evaluate the pitfalls or difficulties they had to face, as well as to compare their results with the objectives they wanted to achieve. © 2008 Wiley Periodicals, Inc.
DHL Bangladesh: Managing headquarters‐subsidiary relations. Comment on DHL Bangladesh: Managing headquarters‐subsidiary relations
Authors: Merchant Hemant , Chand Masud , Michiels Caroline 
Published: April 2008

AbstractThis case revolves around Nurul Rahman, a DHL Bangladesh (DHLB) manager who must recommend which of the two human resource information systems (HRISs) DHLB should adopt to alleviate the escalating workload on its human resources (HR) department. The choice between these systems is difficult: the HRIS favored by regional headquarters is significantly more expensive and likely unsuited to DHLB's unique needs, whereas the HRIS favored by DHLB—although likely effective —seems to be incapable of meeting headquarters' strong preference for streamlining human resource systems across disparate Asian subsidiaries. Rahman must carefully balance conflicting stakeholder interests and do so against the backdrop of a politically powerful headquarters that can “make or break” managerial careers. © 2008 Wiley Periodicals, Inc.
Soap‐based detergent formulations: XIX. Amphoteric alkylsuccinamide derivatives as lime soap dispersants
Authors: Micich T. J. , Linfield W. M. , Weil J. K. 
Published: April 2008

Abstract and SummaryA series of amphoteric surfactants was synthesized by reaction of 1,3‐propanesultone with N‐alkyl‐N′‐(ω,ω‐dimethylaminoalkyl)succinamides. The intermediate succinamides were prepared by reacting methyl N‐alkylsuccinamates, obtained from alkylamines containing 8 to 18 carbon atoms, with N,N‐dimethyl‐1,3‐propylenediamine or N,N‐dimethylethylenediamine neat. The amphoterics were isolated as hygroscopic crystalline solids having superior lime soap dispersing ability, water solubility, and calcium ion stability. Detergency studies at 0.2% concentration (300 ppm water hardness) indicated good washing ability when used alone and excellent performance in combination with soap or in soap‐silicate formulations.
Studies of the fluorescent products of lipid oxidation in aqueous emulsion with glycine and on the surface of silica gel
Authors: Shimasaki Hiroyuki , Privett O. S. , Hara Ichiro 
Published: April 2008

Abstract and SummaryThe formation of fluorescent products in the reaction of methyl linoleate hydroperoxide with glycine in aqueous emulsions correlated directly with the decrease in diene conjugation and the increase in thiobarbituric acid (TBA) reactive substances. These correlations also were reflected in the course of the oxidation of methyl linoleate in aqueous emulsions with glycine and indicated that glycine reacted with products of peroxide decomposition as opposed to intermediates of autoxidation in hydroperoxide formation. Thin layer chromatography (TLC) and selective solvent extraction demonstrated that the products of the reaction contained many substances with a fluorescent spectrum similar to those of lipofuscin pigments. When methyl esters of polyunsaturated fatty acids or other polyunsaturated lipids underwent oxidation adsorbed on silica gel particles, products with similar fluorescent spectral properties were formed illustrating that fluorescent substances were formed in a variety of reactions associated with the oxidation of unsaturated lipids.
Survey of aflatoxins in California tree nuts
Authors: Fuller Glenn , Spooncer W. W. , King A. D. , Schade J. , Mackey B. 
Published: April 2008

Abstract and SummarySurveys of the California walnut and almond crops to determine incidence of aflatoxins are reported. Average proportions of contaminated nuts from the field were one in 28,250 for walnuts and one in 26,500 for almonds. It was shown that there is a high correlation of contamination with damaged nuts which are removed by standard sorting procedures. Statistical treatment of data from the surveys indicates some of the problems in sampling tree nuts for analysis.