Real-time ellipsometry studies of gold thin-film growth

In-situ ellipsometry was used to monitor the growth of Au thin films deposited on SiO2/Si substrates by magnetron sputtering. To analyze the growth curves, which are Delta vs psi curves measured in real time, we introduced various growth models and calculated the effective dielectric constants of the growing films using effective medium approximations. analysis results show that Au thin films do not grow layer-by-layer, rather they grow as islands following the initial nucleation. As the islands grow bigger, they come in contact with each other and coalesce. The Au thin films continue to grow to become continuous films exhibiting surface roughness. The optical characteristics of the Au thin films in the nucleation and coalescence stages are found to be markedly different from those of the bulk Au.