Carbon rehybridization at the graphene/SiC(0001) interface: Effect on stability and atomic-scale corrugation

Abstract

We address the energetic stability of the graphene/SiC(0001) interface and the associated binding mechanism by studying a series of low-strain commensurate interface structures within a density functional scheme. Among the structures with negligible strain, the $6\sqrt{3}\phantom{\rule{-0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{-0.16em}{0ex}}6\sqrt{3}\phantom{\rule{0.16em}{0ex}}R{30}^{\ensuremath{\circ}}$ SiC periodicity shows the lowest interface energy, providing a rationale for its frequent experimental observation. The interface stability is driven by the enhanced local reactivity of the substrate-bonded graphene atoms undergoing $s{p}^{2}$-to-$s{p}^{3}$ rehybridization (pyramidalization). By this mechanism, relaxed structures of higher stability exhibit more pronounced graphene corrugations at the atomic scale.