Growth mechanism of nanoparticles prepared by radio frequency sputtering

Growth mechanisms of nanometer-sized particles prepared by rf sputtering on silica glass layers were examined. Gold and gallium arsenide (GaAs) particles synthesized with varying sputtering times on a SiO2 sputtered layer were subsequently buried in a SiO2 film by sputtering a SiO2 target. Transmission electron microscopy showed that in both cases, with increasing sputtering time, the number density decreased and the distance between neighboring particles increased in the initial stage of the growth, which suggests that the particles migrate on the SiO2 surface and coalesce with each other as they grow. Differences of GaAs and gold particle formation suggest that the mobility of the GaAs particles is much larger than that of gold. The results suggest that the migration of nanoparticles is activated by the bond-formation energy released during the incorporation of precursors into growing particles.