Photoluminescence behavior of silicon nanocrystals produced by hot implantation in SiO2

In this work we present a photoluminescence (PL) study on Si nanocrystals produced by ion implantation on SiO2 targets at temperatures ranging between 25 and 800 °C and subsequently annealed in N2 atmosphere. The PL measurements were performed at low excitation power (20 mW/cm2) in order to avoid nonlinear effects. Broad PL spectra were obtained (from 650 up to 1050 nm), 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.