Characteristic photoluminescence properties of Si nanocrystals in SiO2 fabricated by ion implantation and annealing

We have measured the implantation dose dependence as well as the oxidation effect of the photoluminescence behaviour of Si nanocrystals in SiO2 layers fabricated by ion implantation and a subsequent annealing step. After anne aling at high temperature, a characteristic photoluminescence band, peaking just below the 1.7 eV was observed. The peak energy and the intensity of t he photoluminescence were found to be affected by the dose of implanted Si ions, but to be independent of annealing time and excitation photon energy. We also present experimental results of an oxidation induced continuous pe ak energy shift of the photoluminescence peak up to around 1.8 eV. This pea k energy, however, was found to return to its previous position with re-ann ealing. These results indicate that whilst the excitation photons are absor bed by Si nanocrystals, the emission is not simply due to electron-hole rec ombination inside the Si nanocrystals, but is related to the presence of de fects, most likely located at the interface between the Si nanocrystals and the SiO2, for which the characteristic energy levels are affected by clust er-cluster interactions or the roughness of the interface. (C) 2001 Publish ed by Elsevier Science Ltd.