Nanopatterning of Si(110) surface by ion sputtering: An experimental and simulation study

Nanopatterning of Si(110) surface by the normal incident Ar+ ion sputtering has been conducted as a function of sample temperature (room temperature-800 degrees C) and ion energy (1-5 keV) with the ion flux of 20 mu A/cm(2). The surface morphology was characterized by an atomic force microscope. For ion energy of 1.5 keV, the sputtered surface morphology changes from a dim dot/hole pattern to a distinct dot one with the increasing temperature. On the other hand, at the temperature of 800 degrees C, the nanodot shape of the dot pattern evolves from being circular -> elliptical -> circular -> elliptical with the increasing ion energy in general. A dynamic continuum model is adopted to describe the experimental results, which includes both the Bradley-Harper (BH) mechanism good for the amorphous surface under ion sputtering and the Ehrlich-Schwoebel (ES) one for the crystalline surface. By adjusting the effective surface tension following its temperature- or ion energy-dependence relationship in the BH or ES mechanism-relevant regime, the processes of surface morphology evolution have been simulated, which agrees with the experimental ones.