Nanoscale self-affine surface smoothing by ion bombardment and the morphology of nanostructures grown on ion-bombarded surfaces

Surface smoothing by ion-bombardment with the concomitant formation of self-affine fractal surfaces at nanometer length scales is reviewed. Results of investigation of the dependence of surface smoothing on ion fluence and the threshold fluence for the formation of self-affine surfaces are presented. Finally, the morphology of self-assembled nanostructures grown by molecular beam epitaxy on surfaces of different fractal dimensions is investigated via studies of the roughness scaling exponent and the correlation length. While the self-assembled Ge islands grown on a pristine Si(1 0 0) surface are square or rectangular shaped, those on the ion-irradiated surface are nearly diamond-shaped.