Surface structuring by multiple ion beams

Abstract

We study surface patterns produced by low energy ion sputtering of amorphous targets based on a generalized version of the damped Kuramoto-Sivashinsky equation with the focus on the simultaneous incidence of four identical ion beams. This setup allows us to quantitatively investigate the relevance of anisotropic ion-induced effective surface diffusion in theory and in experiments. We find that hexagonal, square, and superstructure patterns can develop depending on the strength of that anisotropy. Squares and superstructures serve as clear indicators for the presence of ion-induced effective surface diffusion. We also discuss the possibility of simulating multiple ion beam incidence by stepwise rotation of the target.