Ion-Sputter-Induced Nanodots on Si(110): Ion Energy Dependence

Nanodot arrays were formed on Si(110) surface under normal-incident Ar⁺ ion sputtering at substrate temperature of 800°C. The ion flux was 20μA/cm², and the ion energies were 1-5keV. The surface was imaged by an atomic force microscope (AFM). It was found that with the increasing ion energy, the average ellipticity of the dots changes in an oscillating manner; meanwhile the average dot size increases monotonously. Based on a dynamic continuum model, and taking into consideration the asymmetry of the Ehrlich-Schwoebel diffusions along the <100> and <110> crystallographic directions, we carry out the simulations, which reproduce the experimental results qualitatively.