bluuebunny/crossref_metadata_2025_split huggingface dataset:
No clear winner in MEDAL race
Authors: Plant Michael 
Published: March 2007

AbstractPrescribing an anti‐inflammatory medication is becoming an increasingly complicated therapeutic decision. This editorial will explore whether the recently published results of the Multinational Etoricoxib and Diclofenac Arthritis Long‐term (MEDAL) studies help to inform that decision.1 First of all, it is worth reviewing the convoluted background that has been reported as much in the newspapers and financial press as in the medical journals.It was in the 1990s that unacceptable rates of GI toxicity were linked with NSAIDs. MacDonald et al estimated that someone aged over 50 years taking an NSAID had a 0.7 per cent risk of a bleeding or perforated ulcer per year,2 and one out of three of these ulcers would be directly attributable to the drug. Assuming a mortality of 10 per cent it was estimated that NSAID therapy might account for 1200 deaths per year in the UK.Impressive scientific discoveries showed that benefits and toxicity could possibly be separated. Inhibition of cyclo‐oxygenase‐1 (COX‐1) was found to be the mechanism of GI toxicity, whereas a separate enzyme (COX‐2) mediated the suppression of inflammation. This paved the way for the pharmaceutical companies to develop drugs to selectively inhibit COX‐2. These coxib drugs still caused dyspepsia, but they did not seem to carry the serious GI risks of standard NSAIDs. Admittedly, arguments did rage over the reporting of results for celecoxib (Celebrex) and the lessening of the safety advantage by concomitant low‐dose aspirin.At this exciting stage COX‐2 inhibitors were also being considered for treatment of other diseases. The hope that cognitive decline in Alzheimer's disease might be slowed proved unfounded, however.3 Although rofecoxib and celecoxib did reduce the rate of recurrence of colorectal polyps,4 the three‐year studies against placebo provided a unique dataset to identify other long‐term side‐effects, including a fourfold increase in cardiovascular thrombotic events with rofecoxib.5 Amid a flurry of publicity rofecoxib was withdrawn, and safety warnings were sent to all doctors in the UK about COX‐2 inhibitors as a class. Litigation cases were brought, confidence fell and so did share prices. Copyright © 2007 Wiley Interface Ltd
Atomic layer epitaxy of GaMnAs on GaAs(001)
Authors: Ozeki M. , Haraguchi T. , Fujita A. 
Published: March 2007

AbstractA self‐limiting mechanism in atomic layer epitaxy (ALE) has been investigated for the heterogrowth of GaMnAs on GaAs(001) substrate. In the ALE, trimethylgallium, bismethylcyclopentadienylmanganese and trisdimethylaminoarsine were used as source materials of gallium, manganese and arsenic atoms, respectively. Although the growth of GaMnAs was carried out at a high growth temperature of 500 °C, a distinct self‐limiting mechanism was observed for the manganese alloy composition up to 6% and the epitaxial layer had no indications of including MnAs phase. The layer showed an atomically flat surface morphology reflecting the self‐limiting growth. The self‐limiting mechanism was largely affected by the lattice mismatch between GaMnAs epitaxial layer and GaAs substrate. When the manganese alloy composition exceeded 7%, the self‐limiting mechanism was broken and MnAs precipitates were observed in the epitaxial layer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transistor with organic emitter and electrodeposited Au base
Authors: Delatorre R. G. , Munford M. L. , Zhou Q. , Pasa A. A. , Schwarzacher W. 
Published: March 2007

AbstractIn this work we present results from a metal‐base transistor consisting of organic C60 as emitter, an ultra‐thin Au as base and n‐Si as collector. The Au layer was directly electrodeposited on the n‐Si surface from a commercial electrolyte containing K2SO3 and Au sulphite complexes. The fullerene emitter was subsequently evaporated on top of the Au layer. For a base thickness of 10 nm the common‐base current gain is close to 1, which is a strong evidence that the transistor is a permeable base device. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface modification of EPDM in r.f. plasma: process optimization and surface characterization
Authors: Moraes J. H. , Maciel H. S. , Dutra J. C. N. , Mello S. A. C. , da Silva Sobrinho A. S. , Massi M. 
Published: March 2007

AbstractDue to the excellent thermal and mechanical properties, the EPDM rubber is used as protective film in the aerospace industry. However, its chemical composition and structure do not allow good adhesive properties, making necessary a surface treatment to improve adhesion properties. Most of the conventional chemical methods make use pollutant solvents. Cold plasma is a clean technology that becomes an important alternative for treating these material surfaces. In this work we present a study of the EPDM rubber surface treatment by plasma. The process was conducted in a RIE plasma system excited by r.f. power using N2 and Ar gas mixtures. A significant improvement of the surface properties regarding to the adhesion properties was obtained. An optimization of the plasma parameters, such as gas ratio mixture, rf power, total gas pressure and treatment time is presented. The rubber surface properties were analyzed by goniometry and AFM. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman shift on n‐doped amorphous carbon thin films grown by electron beam evaporation
Authors: Rebollo P. B. , Freire L. F. , Lozada M. R. , Palomino M. R. , Jiménez S. S. , Zelaya A. O. 
Published: March 2007

AbstractThe structural properties of carbon thin films synthesized under an atmosphere of nitrogen by means of electron beam evaporation were studied by Raman scattering spectroscopy. The electron beam evaporation technique is an important alternative to grown layers of this material with interesting structural properties. The observed shift of the Raman G band shows that the structure of the films tends to become more graphitic upon the increase of the deposition time. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of Te diffused into GaSb by photoluminescence and HRXRD
Authors: Vargas‐Sanabria R. , Rosendo E. , Martínez J. , Díaz T. , Juárez H. , García G. , Rosendo‐Francisco P. , Rubín M. , de Anda F. 
Published: March 2007

AbstractPhotoluminescence (PL) and High Resolution X‐Ray Diffraction (HRXRD) measurements were used to study the diffusion of Te on GaSb‐p thin films deposited on GaSb‐n substrates by Liquid Phase Epitaxy (LPE). The studied samples consist of an n‐type layer on a p‐type layer to carry out the diffusion. The diffusion process was done through thermic treatment at 450 °C and 2, 4 and 6 hours in to the hydrogen atmosphere. After carrying out the heat treatment, the n‐type layer was removed with the purpose of studying the diffusion behavior of Te. The PL spectra show that when the time of diffusion increases, the signal produced by the exitonic transitions increases its intesity, this can be attributed to the increase of the concentration of Te in the GaSb‐p film. The X‐ray spectra show that in agreement it increases the time of diffusion, the amount of Te increases until having a single peak to 6 hrs of diffusion. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural evolution of nanocrystalline silicon studied by high resolution transmission electron microscopy
Authors: Ponce A. , Benami A. , Santana G. , Alonso J. C. , Aguilar‐Hernández J. , Contreras‐Puente G. , Ortiz A. , Fandiño J. , Romeu D. 
Published: March 2007

Abstract In this work, nanocrystalline silicon (nc‐Si) embedded in amorphous silicon nitride (a‐SixNy) films have been characterized by High Resolution Transmission Electron Microscopy (HRTEM). The films have been grown by remote plasma enhanced chemical vapour deposition (RPECVD) onto silicon substrates using a mixture of SiCl4, NH3 and H2. Subsequently, the sample has been introduced to an annealed process. The nanocrystalline inclusions have been measured from the analysis of HRTEM images. The size of nc‐Si inclusions is modified due to the annealing process. The diameter of nc‐Si inclusions in as‐grown films vary from 1.3 to 3.1 nm. In annealed films, a high density of new clusters with reduction of 1 nm of those diameters is observed, as well as the coalescence phenomenon among some nc‐Si inclusions is observed too. Consequently, the diameters of annealed films nc‐Si inclusions range from 0.7 to 4 nm. The thin films show an excellent photoluminescence emission. The density per unit area and size of the nc‐Si inclusions are correlated with the PL emissions. The influence of the structural changes of the nc‐Si on the PL emissions is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamics of InxGa1–xN MOVPE using x ‐dependent interaction parameter
Authors: Moon Won Ha , Kim Changsung Sean , Choi Chang Hwan 
Published: March 2007

AbstractThermodynamic properties of Inx Ga1–x N MOVPE are investigated using x ‐dependent interaction parameter. The interaction parameter (Ω = –1.3435x + 6.1607 (kcal/mol)) dependent on In composition is calculated using a molecular‐mechanics method to investigate the phase stability of InGaN. This parameter is more reliable than that proposed until now. The phase diagram and critical temperature (1392 K at x = 0.44) of Inx Ga1–x N are also obtained. With this interaction parameter, many thermodynamic characteristics of InGaN by the change of In composition, input V/III ratio, and input mol ratio of group III sources are calculated to predict the growth condition of InGaN. These results are in agreement with other data for InGaN. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and TEM characterization of (AlyGa1–y)1–xInxP layers grown on graded buffers
Authors: Novak J. , Hasenöhrl S. , Kučera M. , Vavra I. , Štrichovanec P. , Kovác J. , Vincze A. 
Published: March 2007

AbstractComposition, crystallographic quality and low temperature photoluminescence of AlGaInP quaternary layers were studied. These layers were grown on the InGaP/GaP graded buffers by metalorganic vapour phase epitaxy. Final composition of the graded buffer top layer was xIn = 0.24. Incorporation of the small amount Al into quaternary led to a substantial improvement of the surface morpohology and crystallographic quality observed in cross‐sectional TEM view. Incorporation of higher amount of Al (above 1%) led to the increase of lattice mismatch, decrease of In content in the alloy and to the indirect band gap. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of PbI2 with admixture of rare earth elements: Electrical and optical properties
Authors: Matuchova M. , Zdansky K. , Zavadil J. 
Published: March 2007

AbstractLead iodide is a promising material applicable for X‐ray and gamma ray detectors operating at room temperature. It has been prepared by direct synthesis of elements lead and iodine and purified by zone melting. The Bridgman‐Stockbarger method has been used for growth of single crystals. The influence of rare earth elements (cerium, gadolinium, terbium, holmium, erbium, thulium and ytterbium) on the quality of resulting material has been investigated. The electrical properties have been studied by the measurement of resistivity. Optical properties have been evaluated by using low temperature photoluminescence spectroscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bidirectional current 4H‐SiC VJFET
Authors: Brosselard P. , Tournier D. , Mihaila A. , Udrea F. , Rashid S. J. , Godignon P. , Amaratunga G. , Millán J. 
Published: March 2007

AbstractSilicon Carbide is an attractive material to develop new generation of power devices due to its outstanding physical and thermal properties. Due to the JFET performances, the reverse mode shows a great interest for power applications particularly concerning bidirectional current capability. Besides, the device temperature behaviour has been characterised up to 300 °C. We have observed excellent temperature performances in the reverse and forward conduction modes since Ron only shows a ×5 and ×4 increase, respectively, from 30 °C to 300 °C. In blocking mode, the leakage current is below the nA range at room temperature and rises the μA range at 300 °C, remaining very low compared to Si devices. In conclusion, one may state that the SiC JFET is a suitable switch for high temperature power applications, showing bidirectional current capability. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of the influence of GaN and AlN as pseudosubstrates on the crystalline quality of InN layers
Authors: Lozano J. G. , Morales F. M. , García R. , Lebedev V. , Cimalla V. , Ambacher O. , González D. 
Published: March 2007

AbstractA study of the impact of different pseudosubstrates as AlN, GaN or AlN/GaN on the crystalline quality of InN layers by transmission electron microscopy is reported. The temperature of the substrate was found to play an important role: for higher temperatures, low quality InN layers are obtained, poorly supported on the buffers and consequently almost free of dislocations; whereas for lower temperatures, higher qualities, with smooth surfaces and continuous interfaces are observed. In these cases, high resolution electron microscopy showed that the high lattice mismatch existing between the pseudosubstrate and the InN epilayer is mainly accommodated by a network of geometrical misfit dislocations at the heterointerface. Additionally, low densities of threading dislocations, also decaying exponentially with the increasing thickness were observed. The introduction of a GaN buffer layer on top of AlN promotes the reduction in one order of magnitude the density of threading dislocations in the epilayer, partially due to the reduction of dislocations propagating from the pseudosubstrate. However, other relevant factors as the domains coalescence or the generation of secondary misfit dislocation must be taken into account. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controlling of hydrogen and oxygen atoms in CdTe by means of far‐infrared spectroscopy using synchrotron radiation
Authors: Cebulski J. , Sheregii E. M. , Polit J. , Marcelli A. , Robouch B. , Castelli Gudi M. , Piccinini M. , Kisiel A. 
Published: March 2007

AbstractThe work presents far‐and middle‐infrared reflectivity spectra collected with synchrotron radiation on specially prepared CdTe‐monocrystals in the temperature region of 30‐300 K. The investigated samples were of three different types characterized by the three different levels of hydrogenation – strong, middle and the low ones. In order to interpret the experimental data, the imaginary part of the dielectric function was evaluated by means of Kramers‐Kronig transformation. To determine quantitatively the influence of hydrogen atoms on the phonon and vibrational spectra of hydrogenated CdTe crystals we used the special statistical model proposed in this paper. This model takes into account the tetrahedron as the basic structural unit and distinguishes the contribution of the hydrogen bearing tetrahedra from the contribution of the hydrogen free ones to the crystal phonon spectra. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the energy band structure of the GaInP/GaAs heterojunction bipolar transistor
Authors: Mimila‐Arroyo J. 
Published: March 2007

AbstractThe GaInP/GaAs heterojunction bipolar transistor energy band gap close to the junction is determined through the behavior of its collector and base currents and current gain as a function of the temperature. It results that the emitter‐base junction is a gradual one with the emitter bandgap, at the place where the carrier injection takes place, being wider than that of the GaAs by just ∼13 meV. It is also shown that for T > 200 K the diffusion contribution to the base current is due to injected holes into the emitter, imposing a strong limitation on the device current gain. Besides, such bandgap difference between the emitter and the base makes the device current gain to decrease as the temperature increases. In view of these results technological modifications are discussed to improve the transistor performance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of the cathodoluminescence spectral shape and intensity of GaN quantum dots under 10 keV electron beam irradiation
Authors: Sieber B. 
Published: March 2007

AbstractIn‐situ degradation experiments are performed by means of plan‐view spectral cathodoluminescence experiments on GaN quantum dots. The influence of the electron beam current density J in the range of 1 to 5.5 A/cm2 is specially studied. Whatever is the J value, the CL peak red‐shifts between 11 and 6 meV and its intensity decreases. Morevoer, a modification of the CL shape is observed which depends on the J value. The results are interpreted in terms of interdiffusion and strain relaxation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of laser shock waves on As implanted HgCdTe
Authors: Yakovyna V. , Berchenko N. , Kuzma M. , Vlasov A. 
Published: March 2007

AbstractThe principal purpose of our research is to show that low‐temperature treatment of materials can be successfully used instead of annealing. Laser shock waves (LSW) were chosen as an alternative to form p‐n junctions in HgCdTe after arsenic ions were implanted. Electrical characteristics of As implanted HgCdTe bulk crystals were studied to determine the effect of LSW generated by nanosecond laser irradiation pulses. The samples were of n ‐type conductivity immediately after the implantation. Then LSW processing was performed under increasingly growing laser beam power density and shock wave pressure. The experiment demonstrated that a threshold shock wave pressure should be reached to ensure the p ‐to‐n conductivity conversion in the surface layer of samples. On the whole the results provide evidence that LSW combined with ion implantation can be used to form p ‐n junctions in HgCdTe. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural study of ferromagnetic Fe‐implanted 6H‐SiC
Authors: Declémy A. , Drouet M. , Eymery J. P. , Dupeyrat C. , Ott F. , Viret M. 
Published: March 2007

AbstractAssociation of multi‐energy ion implantation with magnetic and structural analysis methods, particularly X‐ray diffraction reciprocal space maps (XRD RSM), is shown to be able to give new original information about the microstructure of Fe‐implanted SiC, a good candidate for diluted magnetic semiconductors (DMS) applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of GaN/ZnO bilayers on sapphire by pulsed laser ablation‐deposition
Authors: Muto Hachizo , Nakamura T. , Wang R. , Kusumori T. , Morita K. 
Published: March 2007

AbstractGaN/ZnO and ZnO/GaN bilayers have been fabricated on Al2O3‐c by pulsed laser ablation‐deposition, since such heteroepitaxial multilayers may be helpful for developing devices and lowering the device cost. Their crystallographic qualities are studied by RHEED and XRD as functions of the deposition conditions; temperature (Th), ambient pressure of oxygen and ammonia, and pulse frequency by fixing the fluence of the Nd:YAG fourth harmonic laser (1.0 J/cm2/pulse). Both epitaxial bilayers with (0001) orientation could be fabricated at optimal conditions. GaN layer can grow on ZnO at lower Th (900‐1000 °C) than on Al2O3 (950‐1100 °C) and gives rise to a better epitaxial bilayer than ZnO/GaN bilayer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical effect of diamond‐like carbon film coating of long‐period optical fiber gratings
Authors: Smietana M. , Szmidt J. , Korwin‐Pawlowski M. L. , Bock W. J. 
Published: March 2007

AbstractThe paper presents diamond‐like carbon (DLC) film as a coating for long‐period grating (LPG) optical fiber structure. The spectral response of a DLC‐coated LPG structure is strictly dependent on Radio Frequency Plasma Chemical Vapour Deposition (RF PCVD) process parameters. The paper discusses the influence of DLC deposition time and self‐bias voltage to shift of the LPG resonance peak and explores the possibility of using the structure as a refractometric sensor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low temperature liquid phase epitaxy with Sn‐based solvent
Authors: Abdo F. , Fave A. , Lemiti M. , Pisch A. , Bernard C. 
Published: March 2007

AbstractSilicon thin film is an attractive option for solar cell applications because of their low cost potential. Liquid Phase Epitaxy (LPE) is an interesting technique because it allows growth of single crystal Si film even at low temperature (<800 °C). Main difficulties are the low solubility of silicon in usual solvent and the presence of a native silicon oxide. In this study, we developed a technique using two successive different Sn‐based melts, one to remove native oxide, second one to grow the active layer under argon or hydrogen flow. This technique leads to smooth and homogeneous Si layer presenting a p/p+ structure. Solar cells were fabricated using standard technology. The photo‐generated current density is in the 16‐19 mA/cm2range after of Si3N4coating deposition. To improve active layer thickness and to enlarge the Si solubility, we proposed to use metallic alloys as Si‐Sn‐Cu‐Al. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffused p‐n GaAs junctions with nano/microrelief active interface
Authors: Borkovskaya O. Yu. , Dmitruk N. L. , Horváth Zs. J. , Mamontova I. B. , Sukach A. V. 
Published: March 2007

AbstractThe technology of a submicron p+‐GaAs layer formation on nano/microtextured n ‐GaAs substrate by a low‐temperature (550 °C) diffusion of Zn is elaborated aimed at ensuring both improved optical and good electronic properties of a textured p‐n junction for the photodiode and solar cells (SC) application. The optical, photoelectric and electrical characteristics of the obtained photodiode structures were studied as a function of the surface microrelief morphology of dendritic or quasigrating type, preliminary processing and the process diffusion duration. Different diffusion conditions were shown to be optimal to obtain maximal improving SC efficiency for structure with different microrelief morphology. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of growth conditions on the spatial non‐uniformities of composition in InGaP epitaxial layers
Authors: Gregušová D. , Kučera M. , Hasenöhrl S. , Vávra I. , Štrichovanec P. , Martaus J. , Novák J. 
Published: March 2007

AbstractComposition uniformity of InGaP thick epitaxial layers grown on InGaP/GaP graded buffer structure was studied by stepwise wet chemical etching and low temperature photoluminescence. We compared properties of two epitaxial layers grown by MOCVD technique on different graded buffers. Influence of strain and growth condition on the properties of both epitaxial layer was studied and related to the buffer design. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Barium titanate thin films plasma etch rate as a function of the applied RF power and Ar/CF4 mixture gas mixing ratio
Authors: Werbowy A. , Firek P. , Chojnowski J. , Olszyna A. , Szmidt J. , Kwietniewski N. 
Published: March 2007

AbstractBaTiO3 (BT) nanocrystalline thin films were plasma etched in the course of several experiments which varied in RF power as well as CF4/(CF4 + Ar) gas‐mixing ratio. The maximum etch rate of approximately 30 nm/min was observed for the maximum power (300 W) and pure Ar plasma atmosphere, which indicates that the process is controlled by the physical mechanism of Ar ion bombardment, while the increasing content of chemically active plasma component (CF4) in the gas mixture slows down barium titanate etch rate. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)