Implantation-Induced Nanocavities and Au Nanoparticles in Si and SiO2

In this study, implantation-induced nanocavities have been formed in Si to encapsulate Au particles by H irradiation and annealing. Further Si irradiation was conducted in selected samples to shrink the cavity size and narrow the size distribution. Au was subsequently introduced into the near surface region to a specific dose of 1 10¹⁵ cm^-2 by the same method followed by an anneal at 900-950 C for 30-60 minutes. The annealing results in diffusion and precipitation of metal particles in the cavities. As the metal precipitates start to nucleate, the well-faceted shape of cavities disappears. In addition, we also observed limited Ostwald ripening of precipitates due to the annealing. Wet oxidation and formation of a buried oxide (BOX) were then performed to confine precipitates in an SiO ₂ layer. Results indicate that it is possible to form Au nanoparticles at a precise depth in SiO₂ but it is difficult by the present methods to control their size