Ion beam synthesis of undoped and Er-doped Si nanocrystals

Our recent work on the ion beam synthesis of Si nanocrystals (nc) and Er-doped Si nc is presented. We will show that ion beam processing is a quite powerful way to obtain Si nc embedded within SiO2. These nc have average sizes, photoluminescence (PL) peak position and PL time-decay curves dependent on the annealing temperature. In particular, with increasing annealing temperatures they become larger, with a red-shifted PL and with longer lifetimes (denoting a reduction in non-radiative processes and the presence of more isolated nc). When doped with Er ions the energy is preferentially transferred from the nc to the Er, with Er luminescence intensities orders of magnitude above those of Er-doped SiO2. This is demonstrated to be due to an enhanced excitation cross-section for the Er ions caused by the sensitizer action of the nc. Finally, the insertion of Er-doped Si nc within an optical microcavity will be shown to produce a further luminescence enhancement.