Surface roughness of gold substrates at the nanoscale: An atomistic simulation study

The statistical properties of rough surfaces at the nanoscale are studied using classical molecular dynamics. Atomistic fcc blocks of gold are generated with different crystal orientations, and with rough surfaces having the same root-mean-square roughness with variable power spectral density (PSD) slopes and roll-off wavenumbers. The process of rough surface generation may result in thermodynamically unstable sharp spatial features. In order to relax the structure, the blocks are equilibrated at 300K. It is found that all surfaces experience changes in their roughness, regardless of their crystal orientation or temperature, although the changes are only temperature-independent when T≤0.4Tm. Based on the analyzed PSDs of the equilibrated substrates, two methods for generating pseudo-stable rough surfaces are introduced and discussed.