A refined Ehrlich–Schwoebel effect on the modification of Si surface nanostructures by post ion milling

A modeling work has been conducted on a phenomenon called post ion milling (PIM), a post-treatment of Ar+ ion sputtering to modify nanostructures on solid surface. It was found by experiments that for PIM with a sufficiently low ion flux, both the average dot size and the surface roughness of Si nanodot arrays on Si(1 0 0) decline steadily against milling time. However, the usually adopted Kuramoto–Sivashinsky (KS) model involving the Bradley–Harper (BH) theory failed to explain the experimental results, nor the KS model that combines both the BH and Ehrlich–Schwoebel (ES) effects. We reexamined the ES term in the KS equation, and derived new terms reflecting the ES contribution. With such a modification, the KS model involving both the BH and the refined ES effects finally gave a qualitative explanation to the PIM result.