Ion-induced self-organized dot and ripple patterns on Si surfaces

The evolution of the surface topography during low-energy Ar+ ion beam erosion of silicon surfaces is studied. Depending on ion-beam parameters, a variety of nanostructured patterns with a very narrow size distribution can be developed on the surface. By rotating the sample, ordered nanodots are formed for ion energies ⩾300 eV at normal and oblique ion incidence angles with respect to the surface normal. Dots evolving at oblique ion incidence of 75° show a very high degree of ordering with a mean dot size λ∼30 nm. Without sample rotation at near normal ion incidence angle (∼15°), remarkably ordered ripple structures develop with a wavelength λ∼45 nm. The degree of ordering and size homogeneity of these nanostructures increases with erosion time eventually leading to the most ordered self-organized patterns on Si surfaces reported so far.