ABSTRACTMicroRaman spectroscopy was used for the characterization of heterostructured SiGe/Si nanowires. The NWs were grown with alloyed AuGa catalysts droplets with different Ga compositions aiming to make more abrupt heterojunctions.... more
ABSTRACTMicroRaman spectroscopy was used for the characterization of heterostructured SiGe/Si nanowires. The NWs were grown with alloyed AuGa catalysts droplets with different Ga compositions aiming to make more abrupt heterojunctions. The heterojunctions were first characterized by TEM; then the NWs were scanned by the laser beam in order to probe the heterojunction. The capability of the MicroRaman spectroscopy for studying the heterojunction is discussed. The results show that the use of catalysts with lower Ge and Si solubility (AuGa alloys) permits to achieve more abrupt junctions.
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ABSTRACTGroup IV semiconductor nanowires are characterized by Raman spectroscopy. The results are analyzed in terms of the heating induced by the laser beam on the nanowires. By solving the heat transport equation one can simulate the... more
ABSTRACTGroup IV semiconductor nanowires are characterized by Raman spectroscopy. The results are analyzed in terms of the heating induced by the laser beam on the nanowires. By solving the heat transport equation one can simulate the temperature reached by the NWs under the exposure to a laser beam. The results are illustrated with Si and Si1-xGex nanowires. Both bundles of nanowires and individual nanowires are studied. The main experimental conditions contributing to the nanowire heating are discussed.
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ABSTRACTThe control of the SiGe NW composition is fundamental for the fabrication of high quality heterostructures. Raman spectroscopy has been used to analyse the composition of SiGe alloys. We present a study of the Raman spectrum of... more
ABSTRACTThe control of the SiGe NW composition is fundamental for the fabrication of high quality heterostructures. Raman spectroscopy has been used to analyse the composition of SiGe alloys. We present a study of the Raman spectrum of SiGe nanowires and SiGe/Si heterostructures. The inhomogeneity of the Ge composition deduced from the Raman spectrum is explained by the existence of a Ge-rich outer shell and by the interaction of the NW with the electromagnetic field associated with the laser beam.
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ABSTRACTRaman scattering of Si nanowires (NWs) presents antenna effects. The electromagnetic resonance depends on the electromagnetic coupling of the system laser/NW/substrate. The antenna effect of the Raman signal was measured in... more
ABSTRACTRaman scattering of Si nanowires (NWs) presents antenna effects. The electromagnetic resonance depends on the electromagnetic coupling of the system laser/NW/substrate. The antenna effect of the Raman signal was measured in individual NWs deposited on different substrates, and also free standing NWs in air. The one phonon Raman band in NWs can reach high intensities depending on the system configuration; values of Raman intensity per unit volume more than a few hundred times with respect to bulk substrate can be obtained.
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ABSTRACTNanocrystals embedded in an oxide matrix have been fabricated by annealing SiGeO films deposited by LPCVD. The composition of the oxide layers and its evolution after annealing as well as the presence and nature of nanocrystals in... more
ABSTRACTNanocrystals embedded in an oxide matrix have been fabricated by annealing SiGeO films deposited by LPCVD. The composition of the oxide layers and its evolution after annealing as well as the presence and nature of nanocrystals in the films have been studied by several experimental techniques. The results are analyzed and discussed in terms of the main deposition parameters and the annealing temperature.
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Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non... more
Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. However, the Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for Si nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation.
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ABSTRACTSemiconductor nanowires (NWs) are fundamental structures for nanoscale devices. The excitation of NWs with laser beams results in thermal effects that can substantially change the spectral shape of the spectroscopic data. In... more
ABSTRACTSemiconductor nanowires (NWs) are fundamental structures for nanoscale devices. The excitation of NWs with laser beams results in thermal effects that can substantially change the spectral shape of the spectroscopic data. In particular, the interpretation of the Raman spectrum is greatly influenced by excitation induced temperature. A study of the interaction of the NWs with the excitation laser beam is essential to interpret the spectra. We present herein a finite element analysis of the interaction between the laser beam and the NWs. The resultas are applied to the interpretation of the Raman spectrum of bundles of NWs.
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Raman spectroscopy provides nondestructive information about nanoscaled semiconductors by modeling the phonon confinement effect. However, the Raman spectrum is also sensitive to the temperature, which can mix with the size effects... more
Raman spectroscopy provides nondestructive information about nanoscaled semiconductors by modeling the phonon confinement effect. However, the Raman spectrum is also sensitive to the temperature, which can mix with the size effects borrowing the ...
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The results of routine influenza surveillance in 13 regions in the Philippines from 2006 to 2012 are presented, describing the annual seasonal epidemics of confirmed influenza virus infection, seasonal and alert thresholds, epidemic... more
The results of routine influenza surveillance in 13 regions in the Philippines from 2006 to 2012 are presented, describing the annual seasonal epidemics of confirmed influenza virus infection, seasonal and alert thresholds, epidemic curve, and circulating influenza strains. Retrospective analysis of Philippine influenza surveillance data from 2006 to 2012 was conducted to determine seasonality with the use of weekly influenza positivity rates and calculating epidemic curves and seasonal and alert thresholds using the World Health Organization (WHO) global epidemiological surveillance standards for influenza. Increased weekly influenza positive rates were observed from June to November, coinciding with the rainy season and school opening. Two or more peaks of influenza activity were observed with different dominant influenza types associated with each peak. A-H1N1, A-H3N2, and two types of B viruses circulated during the influenza season in varying proportions every year. Increased i...
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ABSTRACT We consider the problem u tt -u xx =εf(t,x,u),(1) u(0,x)=u(2π,x),u t (0,x)=u t (2π,π),0<x<π,(2) u(t,0)=u(t,π)=0,0≤t·(3) We propose a method to analyze the problem (1)–(3), leading to sufficient conditions for the... more
ABSTRACT We consider the problem u tt -u xx =εf(t,x,u),(1) u(0,x)=u(2π,x),u t (0,x)=u t (2π,π),0<x<π,(2) u(t,0)=u(t,π)=0,0≤t·(3) We propose a method to analyze the problem (1)–(3), leading to sufficient conditions for the existence of a solution, and a constructive method to obtain approximate solutions that converge to the exact solution in a specified norm.
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Papers in this Volume were published in print format as an Appendix of Volume 1617http://journals.cambridge.org/issue_MRS Online Proceedings Library/OPL1617no-1
We have performed angular momentum projection with double-constrained Hartree-Fock-Bogoliubov wave functions with the Gogny interaction for the 32 Mg . We show that the more relevant degree of freedom is the quadrupole deformation. Minima... more
We have performed angular momentum projection with double-constrained Hartree-Fock-Bogoliubov wave functions with the Gogny interaction for the 32 Mg . We show that the more relevant degree of freedom is the quadrupole deformation. Minima of the ground state obtained in single-constrained calculations with this operator are hardly modified in double-constrained calculations insuring thereby the stability of the solution.
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O trabalho discute o posicionamento de técnicos de nível superior do Instituto Chico Mendes de Conservação da Biodiversidade ICMBIO , em exercício na Amazônia Brasileira, em relação ao ambientalismo e identifica possíveis relações entre... more
O trabalho discute o posicionamento de técnicos de nível superior do Instituto Chico Mendes de Conservação da Biodiversidade ICMBIO , em exercício na Amazônia Brasileira, em relação ao ambientalismo e identifica possíveis relações entre os posicionamentos e visões do conhecimento, concepção de Reserva Extrativista RESEX e de extrativismo. Consoante a base teórica discutida, foram adotadas as seguintes tipologias para as categorias estudadas: correntes ou vertentes ambientalistas: preservacionista, Sustentabilista e Socioambientalista; visões do conhecimento: anarquista, dialógica ou saber ambiental ; interdisciplinar; e, científica pura; visões de RESEX: RESEX como Unidade de Conservação UC de uso sustentável, RESEX servindo à reforma agrária e RESEX oportunista; visões sobre extrativismo: extrativismo legítimo, extrativismo falido e extrativismo oportunista. O método utilizado foi o comparativo com partições cruzadas, verificando similaridades e dissimilaridades de grupos de respon...
Silicon oxide films with excess of Si were deposited by Low Pressure Chemical Vapor Deposition. The growth rate of the films and the excess of silicon in them have been modeled using a Face-centered Central Composite Design experiment.... more
Silicon oxide films with excess of Si were deposited by Low Pressure Chemical Vapor Deposition. The growth rate of the films and the excess of silicon in them have been modeled using a Face-centered Central Composite Design experiment. Samples annealed at 1100°C show luminescence (665 nm) at 80K and at room temperature associated to Si nanocrystals.
We conducted an unlinked seroprevalence survey in a community-based sample of 2,203 adults to estimate the prevalence of hepatitis B and C virus markers in the general adult population of the Murcia region (Spain). The influence of age,... more
We conducted an unlinked seroprevalence survey in a community-based sample of 2,203 adults to estimate the prevalence of hepatitis B and C virus markers in the general adult population of the Murcia region (Spain). The influence of age, sex and place of residence on the seroprevalence of hepatitis was investigated. The overall prevalence was 10.2% for anti-HBc antibodies, 0.9% for HBsAg, and 1% for anti-HCV. There was a trend of increasing prevalence with age for anti-HBc and anti-HCV regardless of sex and urban or rural residence. The prevalence of hepatitis B and C markers was higher in individuals living in urban areas, although there was no significant association. The results indicate that the Murcia region may be considered an area of low-intermediate endemicity for hepatitis B virus infection. This is one of the first reports assessing the prevalence rate for hepatitis C markers for a general population in Europe.
Research Interests: Epidemiology, Adolescent, Spain, Hepatitis B, Humans, and 11 moreFemale, Male, Infectious, Clinical Sciences, Scandinavian, Aged, Prevalence, Middle Aged, Adult, Sex Factors, and Age Factors
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A beyond-mean-field theory of new generation has been developed and applied for the first time to discuss the controversial N=32 and/or N=34 shell closures and the puzzling behavior of the transition probabilities from the ground to the... more
A beyond-mean-field theory of new generation has been developed and applied for the first time to discuss the controversial N=32 and/or N=34 shell closures and the puzzling behavior of the transition probabilities from the ground to the first 2(+) state in the titanium isotopes. In the numerical applications, the finite range density dependent Gogny interaction has been used. As compared with the experimental data for several calcium, titanium, and chromium isotopes, we obtain a good agreement for the excitation energies and a reasonable one for the transition probabilities. Our calculations support a shell closure for N=32 but not for N=34.
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Restricted variation after projection and the Lipkin-Nogami methods. Tomás R. Rodríguez * , JL Egido , and LM Robledo Departamento de Física Teórica C-XI, Universidad Autónoma de Madrid, E-28049 Madrid, Spain. Received 12 July 2005;... more
Restricted variation after projection and the Lipkin-Nogami methods. Tomás R. Rodríguez * , JL Egido , and LM Robledo Departamento de Física Teórica C-XI, Universidad Autónoma de Madrid, E-28049 Madrid, Spain. Received 12 July 2005; published 8 December 2005 ...
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Page 1. Towards full variation after projection solutions through restricted variational spaces This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2006 Phys. Scr. 2006 216... more
Page 1. Towards full variation after projection solutions through restricted variational spaces This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2006 Phys. Scr. 2006 216 (http://iopscience.iop.org/1402-4896/2006/T125/058) ...
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The crystallization kinetics and film microstructure of poly-SiGe layers obtained by solid-phase crystallization of unimplanted and C- and F-implanted 100-nm-thick amorphous SiGe films deposited by low-pressure chemical vapor deposition... more
The crystallization kinetics and film microstructure of poly-SiGe layers obtained by solid-phase crystallization of unimplanted and C- and F-implanted 100-nm-thick amorphous SiGe films deposited by low-pressure chemical vapor deposition on thermally oxidized Si wafers were studied. After crystallization, the F- and C-implanted SiGe films showed larger grain sizes, both in-plane and perpendicular to the surface of the sample, than the unimplanted SiGe films. Also, the (111) texture was strongly enhanced when compared to the unimplanted SiGe or Si films. The crystallized F-implanted SiGe samples showed the dendrite-shaped grains characteristic of solid-phase crystallized pure Si. The structure of the unimplanted SiGe and C-implanted SiGe samples consisted of a mixture of grains with well-defined contour and a small number of quasi-dendritic grains. These samples also showed a very low grain-size dispersion.