Nanoscale self-affine surface smoothing by ion bombardment

The topography of silicon surfaces irradiated by a 2-MeV Si⁺ ion beam at normal incidence and ion fluences in the range 10¹⁵--10¹⁶ions/cm² has been investigated using scanning tunneling microscopy. At length scales below {~}50 nm, surface smoothing is observed; the smoothing is more prominent at smaller length scales. The smoothed surface is self-affine with a scaling exponent {α}=0.53±{}0.03.