Formation of large-area nanostructures on Si and Ge surfaces during low energy ion beam erosion

Abstract

In this contribution results on self-organized patterns formed during low energy Xe+ ion beam erosion on Si and Ge surfaces are presented. It was found that the evolution of surface patterns depends on ion incidence angle, erosion time, and ion energy. In the case without sample rotation ripple patterns form on the Si and Ge surfaces with a wavelength λ<100nm, for ion energies Eion⩽2000eV at near normal ion incidence (αion∼5°) and at room temperature. The experimental results of a decreasing ripple wavelength with ion incidence angle on Si coincide with the Bradley-Harper [J. Vac. Sci. Technol. A 6, 2390 (1988).] theory of ripple formation. While the independency of λ from the ion flux suggests that thermally activated surface diffusion can be ruled out as the dominant relaxation mechanism. Experiments reveal that the wavelength of ripples increases with ion energy. With sample rotation at 75° ion incidence angle dot patterns form on the surface with a mean size λ<50nm.