Formation and coarsening of near-surface Ga nanoparticles on SiNx

We have investigated the formation and coarsening of near-surface Ga nanoparticles (NPs) in SiNx using Ga+ focused-ion-beam-irradiation of SiNx, followed by rapid thermal annealing. For surfaces with minimal curvature, diffusive growth is apparent, leading to nearly close packed arrays with NP diameters as small as 3 nm and densities as high as ∼4 × 1012 cm−2. The diffusive flux increases with annealing temperature, leading to NP coarsening by Ostwald ripening. For surfaces with increased curvature, diffusion towards the valleys also increases during annealing, leading to Ga NP coalescence and a bi-modal distribution of NP sizes.