Mechanisms of pit coarsening in ion erosion of fcc(111) surfaces: a kinetic 3D lattice Monte-Carlo study

An atomic simulation approach to ion erosion of fcc(111) surfaces is presen ted. In a fully 3D kinetic lattice Monte-Carlo model thermodynamically acti vated processes Like adatom, step-edge or surface vacancy diffusion are com bined with ballistic effects due to single ion impacts, i,e. sputtering, ad atom and surface vacancy generation. In the course of erosion nucleation of surface vacancy islands, their growth, both laterally and vertically, and subsequent coarsening of these pits is observed. For removal of up to Theta = 6 monolayers the evolution of the surface is characterized in terms of t he roughness and height-height correlation function. The simulation results are discussed with respect to low-energy noble gas ion erosion experiments of Pt(111) surfaces [M. Kalff et al., Surf. Sci. 486 (2001) 103, preceding paper]. By explicitly tuning specific atomic transitions within the simula tion it is demonstrated, that forbidden thermal adatom generation does hard ly influence the surface evolution. Suppressed step-edge diffusion, however , considerably slows down pit coarsening and impedes pit shape relaxation, emphasizing the importance of this smoothening process in ion erosion, (C) 2001 Elsevier Science B.V. All rights reserved.