RF-sputtering of gold on silica surfaces: evolution from clusters to continuous films

Au/SiO2 nanosystems were prepared by RF-sputtering of gold from Ar plasmas on amorphous silica substrates at temperatures as low as 60°C. The interrelation between nanosystem properties and synthesis conditions was investigated in detail, with particular attention to the nucleation and coalescence processes of Au nanoparticles on the SiO2 surface. To this regard, special emphasis was given to the interplay between the system morphology and the resulting optical properties, as probed by both in-situ and ex-situ characterization techniques. In this context, Spectroscopic Ellipsometry (SE) enabled to gain important information on the energy dispersion of the complex dielectric function and, subsequently, on the evolution from dispersed clusters to continuous films. Such variations were tailored by proper combinations of the bias potential (Vbias) and deposition time, indicating the possibility of a fine modulation of the optical response.