Self-Ordering of Nanofacets on Vicinal SiC Surfaces

Abstract

Vicinal $4H$ and $6H\mathrm{\text{−}}\mathrm{S}\mathrm{i}\mathrm{C}(0001)$ surfaces have been investigated using atomic force microscopy and cross-sectional high-resolution transmission electron microscopy. We observed the characteristic self-ordering of nanofacets on any surface, regardless of polytypes and vicinal angles, after gas etching at high temperature. Two facet planes are typically revealed: (0001) and high index $(11\overline{2}n)$ that are induced by equilibrium surface phase separation. A $(11\overline{2}n)$ plane may have a free energy minimum due to attractive step-step interactions. The differing ordering distances in $4H$ and $6H$ polytypes imply the existence of SiC polytypic dependence on nanofaceting. Thus, it should be possible to control SiC surface nanostructures by selecting a polytype, a vicinal angle, and an etching temperature.