Effect of ageing on the luminescence intensity and lifetime of porous silicon: roles of recombination centers

Ageing effect on the photoluminescence spectra and lifetime of porous silicon are analyzed in a set of samples containing particles with various sizes. The ageing causes a pronounced increase in the intensity from the sample containing large particles, whereas it causes only a small increase for the sample containing smaller ones. The origin of this phenomenon is the difference in initial concentrations of non-radiative centers in the samples and their passivation in the air. The transition of emission mechanism from recombination between quantum confined states to recombination via radiative centers, as well as passivation levels, have no effect on the dependence of the decay rate on emission energy. The received results reveal strong correlation between particle size, intensity and decay rate during the ageing. (C) 2002 Elsevier Science B.V. All rights reserved.