Optical Phonon
Mostrando 1-12 de 38 artigos, teses e dissertações.
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1. Structural and Optical Properties of GaN Thin Films Grown on Si (111) by Pulsed Laser Deposition
In this work we present results and analysis concerning the processing and characterization of Gallium Nitride (GaN) thin films (TF) grown on Si (111) substrates by pulsed laser deposition technique (PLD), which were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and Raman spectroscopy (RS). The GaN films show
Mat. Res.. Publicado em: 14/01/2019
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2. Produção e caracterização de vidros de telureto tridopados com íons de terras raras e nanopartículas metálicas para uso em displays coloridos. / Production and characterization of tellurite glasses doped with rare earth ions and metallic nanoparticles for use in color displays.
This works presents studies of the production and the characterization of TeO2 -PbO-GeO2 doped with erbium, thulium and ytterbium ions and also prepared with different metallic nanoparticles for applications in displays. This glass system presents a broad transmission window in the visible and infrared (350 - 6500 nm), high solubility for rare earth ions, lo
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 08/04/2011
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3. Propriedades magneto-óticas e de magneto-transporte de um diodo de tunelamento ressonante contendo Si δ - doping no poço quântico
In this work, we have studied the transport and optical properties of GaAs = AlGaAs resonant tunneling diodes with Si delta-doping at the center of the quantum well. We have studied magneto-transport and polarized resolved photoluminescence from GaAs quantum well and contact layers as a function of applied voltage and magnetic _eld parallel to the tunnel cur
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 11/03/2011
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4. Hot electron transport properties in characteristics of wurtzite GaN MESFETs using a five-valley model
Ensemble Monte Carlo simulations have been carried out to investigate the effects of upper valleys on the characteristics of wurtzite GaN MESFETs. Electronic states within the conduction band valleys at the Γ1, U, M, Γ3 and K are represented by non-parabolic ellipsoidal valleys centred on important symmetry points of the Brillouin zone. The following scatt
Brazilian Journal of Physics. Publicado em: 2010-09
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5. Aspectos eletrônicos e estruturais do grafeno e derivados:: um estudo teórico-experimental
In this work we study the electronic and structural properties of graphene and graphene based materials by means of experimental and theoretical techniques. By means of ab-initio calculations using the Density Funcional Theory (DFT), we study the effect of pressure on graphene multi-layers. We look for an explanation for experimental results on the charge in
Publicado em: 2010
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6. Estudo da interação elétron-fônon em nanotubos de carbono por Espectroscopia Raman Ressonante
In this work, we have used resonance Raman spectroscopy to the study of carbon nanotubes. We reviewed the literature concerning their structural, electronic and vibrational properties, emphasizing the role of many-body effects, particularly the electron-phonon interaction, on the latter two properties. We also reviewed how Raman spectroscopy can be applied t
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 01/09/2009
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7. Influência da radiação gama em filmes de PPV e PTHT: caracterização óptica e elétrica
In this work, we investigated the effects of Gamma ionizing radiation on optical properties of the polyeletrolite poly (chloride Tetrahydrothiophen of xililideno) (PTHT) and the conjugated polymer poly(p- phenylene vinileno) (PPV). The PPV films were processed from PTHT films and it was submitted on the annealing step at low (110oC) and higher (200oC) under
Publicado em: 2009
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8. Propriedades física de molécilas orgânicas e compostos do tipo perovskita CdSiO3 e CaPbO3
In the first part of this work our concern was to investigate the thermal effects in organic crystals using the theory of the polarons. To analyse such effect, we used the Fröhlichs Hamiltonian, that describes the dynamics of the polarons, using a treatment based on the quantum mechanics, to elucidate the electron-phonon interaction. Many are the forms to a
Publicado em: 2009
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9. Síntese e caracterização de vidros de telureto dopados com íons de Eu3+ e Tb3+ com nanopartículas metálicas. / Synthesis and characterization of tellurite glasses doped with Eu3+ and Tb3+ ions with metallic nanoparticles.
This work presents the synthesis and characterization of luminescent properties of vitreous systems TeO2-ZnO e TeO2-ZnO-PbO-Na2O doped with ions of europium and terbium containing silver, gold and copper nanoparticles (NPs), for applications in photonic devices. These glasses have a large window transmission (350-6500 nm), chemical stability, mechanical and
Publicado em: 2009
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10. Processos litográficos em filmes epitaxiais de compostos IV-VI para medidas Hall e o estudo da dopagem do telureto de chumbo com flureto de bário / Lithographic processes in epitaxial films of IV-VI compounds for Hall measurements and the study of lead telluride doping with barium flouride
The first part of the work dealt with the application of lithographical techniques to fabricate Hall geometry of IV-VI films grown on (111) BaF_2 substrates. A previous study of In diffusion in PbTe films confirmed the viability of using In as a metallic contact. During the lithographic process, some solutions were implemented to resolve the problems generat
Publicado em: 2009
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11. Interação plasmon-fônon LO em superredes semicondutoras
This work presents a Raman investigation of the optical vibrations in highly doped In-GaAs/InP and GaAs/AlGaAs superlattices (SLs). The InGaAs/InP SLs grown with different periods were analyzed using polarized Raman techniques. No Raman selection rules were found in the long period InGaAs/InP SLs due to the structural defects in the bulk materials constituti
Publicado em: 2008
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12. Estudo de filmes finos de GaAS (1-x) Nx/GaAS por espectroscopia Raman e de Fotoluminescência
The dependence of nitrogen (N) concentration on optical properties in thermally treated and as grown thin films of GaAs1−xNx, with 0, 0144 x 0, 0370, is investigated through Raman spectroscopy and Photoluminescence. Raman spectra exhibits the presence of two GaAs1−xNx characteristic modes. A systematic decrease of the longitudinal optical GaAs-ty
Publicado em: 2008