Graphene on the C-terminated SiC (000 $\bar{1}$) surface: An ab initio study

TL;DR

This study uses ab initio calculations to analyze the atomic and electronic structures of graphene on the C-terminated SiC surface, revealing minimal substrate interaction and explaining observed rotational disorder.

Contribution

It provides the first detailed ab initio analysis of graphene on the C-terminated SiC surface, highlighting differences from the Si-terminated face and the role of Si adatoms.

Findings

No C buffer layer on the C-terminated surface.

Graphene exhibits linear dispersion with weak substrate interaction.

Stacking geometry has little effect on interaction and disorder.

Abstract

The atomic and electronic structures of a graphene layer on top of the $(2\times2)$ reconstruction of the SiC (000$\bar{1}$) surface are studied from ab initio calculations. At variance with the (0001) face, no C bufferlayer is found here. Si adatoms passivate the substrate surface so that the very first C layer presents a linear dispersion characteristic of graphene. A small graphene-substrate interaction remains in agreement with scanning tunneling experiments (F.Hiebel et al. {\it Phys. Rev. B} {\bf 78} 153412 (2008)). The stacking geometry has little influence on the interaction which explains the rotational disorder observed on this face.