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Photoluminescence behavior of Si nanocrystals as a function of the implantation temperature and excitation power density

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Photoluminescence behavior of Si nanocrystals as a function of the implantation temperature and excitation power density

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Título Photoluminescence behavior of Si nanocrystals as a function of the implantation temperature and excitation power density
Autor Sias, Uilson Schwantz
Amaral, Livio
Behar, Moni
Boudinov, Henri Ivanov
Moreira, Eduardo Ceretta
Ribeiro, Euripedes
Abstract In this work we present a study of photoluminescence PL on Si nanocrystals NC produced by ion implantation on SiO2 targets at temperatures ranging between room temperature and 800 °C and subsequently annealed in N2 atmosphere. The PL measurements were performed at low excitation power density (20 mW/cm²) in order to avoid nonlinear effects. Broad PL spectra were obtained, presenting a line-shape structure that can be reproduced by two superimposed peaks at around 780 and 950 nm. We have observed that both PL intensity and line-shape change by varying the annealing as well as the implantation temperatures. Implantations performed at 400 °C or higher produce a remarkable effect in the PL line shape, evidenced by a strong redshift, and a striking intensity increase of the peak located at the long-wavelength side of the PL spectrum. In addition we have studied the PL dependence on the excitation power density (from 0.002 to 15 W/cm²) . The samples with broad NC size distribution containing large grains, as revealed by transmission electron microscopy observations presented a PL spectrum whose line shape was strongly dependent on the excitation power density. While high excitation power densities (saturation regime) induce only the short-wavelength part of the PL spectrum, low excitation power densities bring out the appearance of the hidden long-wavelength part of the emission. The present results are explained by current models.
Contido em Journal of applied physics. Vol. 98, no. 3 (Aug. 2005), 034312 6p.
Assunto Fotoluminescencia
Microscopia eletronica de transmissao
Semicondutores elementares
Silicio
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/96096
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