Nanostructuring of Si(100) by Normal-Incident Ar⁺ Ion Sputtering at Low Ion Flux

We investigate Si(100) surface morphology evolution under normal-incident Ar⁺ ions sputtering with low ion flux of 20μA/cm². The results indicate that under the low flux ion sputtering, the nanostructuring process of Si(100) is governed by the Ehrlich--Schwoebel (ES) mechanism, rather than by the Bradley--Harper (BH) one for the case of high flux (normally the order of 10² μA/cm² or larger). This work reveals that the ion flux plays an important role in the surface morphology evolution under ion sputtering, and a usually accepted classification that the ES mechanism is related to metal single-crystals under ion sputtering, while the BH one is to amorphous, and semiconductor targets is questionable.