Investigation of the early stages of condensation of Ag and Au on the amorphous carbon surface during thermal evaporation under vacuum

The formation of arrays of Ag and Au nanoparticles from the vapor deposition phase on an unheated thin-film amorphous carbon substrate has been systematically investigated using transmission electron microscopy. It has been found that there is a significant dependence of the size of particles and the density of their location on the surface on the amount of evaporated silver or gold. In particular, for a gold sample weighing ∼2 mg, the predominant diameter of clusters is ∼9 nm at a surface distribution density of ∼10000 μm−2, whereas during evaporation of a larger sample weighing ∼11 mg, the predominant diameter of clusters is ∼35 nm at a surface distribution density of ∼200 μm−2. A phenomenological description of the formation of an array of nanoparticles through thermal evaporation and condensation under vacuum onto an unheated surface has been presented. The specific features of the process have been considered. It has been concluded that the nucleation of a silver or gold particle on the surface gives rise to a flow of vaporous silver or gold, which is directed to this particle and, thus, maintains it in a hot state and determines its growth.