Temperature induced change of surface roughness of Au(1 1 1) epitaxial films on mica

Abstract

The epitaxial growth of Au(1 1 1) on mica was studied using scanning tunneling microscopy (STM). Structure and surface roughness of 100 nm thick films evaporated at substrate temperature in the range 580–890 K was examined at deposition rates of 0.2 and 0.5 nm/s. Decrease of the surface roughness at some temperature depending on the deposition rate was observed. It can be explained considering a critical island size R c at which a new layer nucleates on top of the Au(1 1 1) island. The critical size increases with temperature much faster than the size of available 3D islands formed during coalescence on mica substrate. Consequently, at lower temperatures 2D nucleation on the top of pre-deposited 3D Au islands can be observed while at higher temperatures no nucleation takes place and adatoms fill gaps between islands.