Size-dependent effect of ion bombardment on Au nanoparticles on top of various substrates: Thermodynamically dominated capillary forces versus sputtering

Hexagonally ordered arrays of Au nanoparticles exhibiting narrow size distributions were prepared on top of Si wafers with either a thin native oxide or a thick thermally oxidized layer as well as on top of crystalline (0001)-oriented sapphire substrates. Subsequent irradiation of these nanoparticles by 200 keV Ar{sup +} and Xe{sup +}, respectively, in combination with transmission electron microscopy analysis (TEM) corroborated the previously reported phenomenon of bombardment-induced burrowing of metallic nanoparticles into SiO{sub x} while conserving their spherical shape [X. Hu et al., J. Appl. Phys. 92, 3995 (2002)]. Performing the ion irradiations on particle ensembles of different radii R{sub 0} (1.3 nm{