1990

Likonen, Jari

The binary collision lattice simulation code COSIPO has been used and developed further in order to investigate the sputtering of Cu atoms by Ar ions, collision cascade anisotropies, and the mechanisms behind these phenomena.The sputtering yields, angular distributions, energy distributions and space distributions of the original positions of the sputtered atoms have been calculated for various target structures.The effect of various model parameters in treating the binary collisions was studied.A combination of model parameters was found that relatively accurately reproduces experimental angular distributions and yields.A novel method to study collision cascade anisotropies and their relation to sputtering has been developed for the monocrystalline target.Calculations showed that the preferential ejection directions of sputtering are directly related to the anisotropies of cascade development.The contribution of collision sequence mechanisms to cascades and sputtering has been determined.The sensitivity of the angular distributions of the sputtered atoms on the near-surface structure and the Lehmann-Sigmund model have been studied by varying the thickness of a thin monocrystalline (amorphous) layer on top of the amorphous (monocrystalline) bulk.