Structure and morphology of annealed gold films galvanically displaced on the Si(111) surface

The effects of thermal treatment in ultrahigh vacuum (UHV) of gold films galvanically displaced on the Si(111) surface are studied with low-energy electron diffraction, Auger electron spectroscopy, atomic force microscopy, Kelvin probe force microscopy, and X-ray photoelectron spectroscopy. Annealing the galvanically displaced gold on Si substrates to 1100 K produces films with similar structure, composition, and morphology to annealed gold films evaporated on Si in UHV. The surface morphology is consistent with the Stranski-Krastanov growth mode. Compared to the unannealed film, an interfacial gold silicide layer forms upon annealing, although with limited improvement in adhesion. We report the formation of submicrometer Au/Si islands with narrow size dispersion, separated by deep trenches and with local order and shape dictated by the symmetry of the substrate. A mechanism for the formation of these islands is proposed.