Nanostructuring of silicate glass under low-energy Ag-ion implantation

Silicate glasses implanted by 30 keV Ag+ ions with a dose of 5 × 1016 ion/cm2 at ion current densities from 4 to 15 μA/cm2 were investigated using optical spectroscopy and atomic force microscopy (AFM). Optical spectroscopy measurements show a characteristic absorption band of surface plasmon resonance that is associated with nanosize Ag particles formed in the implanted glasses. Observed both the shift of transmittance band minimum to long wavelengths and the intensity change with rise of ion current density are caused by increase of the nanoparticle sizes. AFM images of the implanted glass surfaces show a formation of semispherical hills. These hills are tops of the spherical nanoparticles towering above the surface due to sputtering of the glass surface layer under the implantation. The increase of ion current density leads to enlarge of the hill size, i.e. nanoparticles. The nanoparticle enlargement is explained in terms of enhanced thermal diffusion of the implanted Ag atoms. Increase of the ion current density leads to temperature rise in the glass matrix that elevates atoms mobility and causes effective collection of the silver atoms into nucleated particles and their growth.