The location and size distribution of silicon nanocrystals (Si-nc) formed in SiO2 by Si ion implantation and annealing were investigated. Transmission electron microscopy images revealed that the location and size distribution of the Si-nc were strongly correlated with the location of the vacancies produced in the SiO2 network by the implantation, as simulated by stopping and range of ions in matter and measured by positron annihilation spectroscopy. Simultaneous consideration of positron annihilation spectroscopy and photoluminescence measurements suggested that the diffusion necessary for Ostwald ripening of Si-nc depends on the concentration and location of vacancy-type defects, and when the majority of these defects were removed by annealing, the growth of the Si-nc slows dramatically or stops entirely. The capability for modification and enhancement of emission from Si-nc through the controlled introduction of defects into the oxide prior to annealing was demonstrated.

Role of Vacancy-Type Defects in the Formation of Silicon Nanocrystals. C.R.Mokry, P.J.Simpson, A.P.Knights: Journal of Applied Physics, 2009, 105[11], 114301