Ion beam synthesis of undoped and Er-doped Si nanocrystals

Our recent work on the ion beam synthesis of Si nanocrystals (nc) and Er-do ped Si nc is presented. We will show that ion beam processing is a quite po werful way to obtain Si nc embedded within SiO2. These nc have average size s, photoluminescence (PL) peak position and PL time-decay curves dependent on the annealing temperature. In particular, with increasing annealing temp eratures they become larger, with a red-shifted PL and with longer lifetime s (denoting a reduction in non-radiative processes and the presence of more isolated nc). When doped with Er ions the energy is preferentially transfe rred from the nc to the Er, with Er luminescence intensities orders of magn itude above those of Er-doped SiO2. This is demonstrated to be due to an en hanced excitation cross-section for the Er ions caused by the sensitizer ac tion of the nc. Finally, the insertion of Er-doped Si nc within an optical microcavity will be shown to produce a further luminescence enhancement. (C ) 2001 Elsevier Science B.V. All rights reserved.