| Autor: |
Sias, U. S., Amaral, L., Behar, M., Boudinov, H., Moreira, E. C., Ribeiro, E. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 8/1/2005, Vol. 98 Issue 3, p034312, 6p, 1 Black and White Photograph, 7 Graphs |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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