  The buffer carbon layer obtained in the first instance by evaporation of Si
from the Si-rich surfaces of silicon carbide (SiC) is often studied only as the
intermediate to the synthesis of SiC supported graphene. In this work, we
explore its intrinsic potentialities, addressing its structural and electronic
properties by means Density Functional Theory. While the system of corrugation
crests organized in a honeycomb super-lattice of nano-metric side returned by
calculations is compatible with atomic microscopy observations, our work
reveals some possible alternative symmetries, which might coexist in the same
sample. The electronic structure analysis reveals the presence of an electronic
gap of ~0.7eV. In-gap states are present, localized over the crests, while
near-gap states reveal very different structure and space localization, being
either bonding states or outward pointing p orbitals and unsaturated Si
dangling bonds. On one hand, he presence of these interface states was
correlated with the n-doping of the monolayer graphene subsequently grown on
the buffer. On the other hand, the correlation between their chemical character
and their space localization is likely to produce a differential reactivity
towards specific functional groups with a spatial regular modulation at the
nano-scale, opening perspectives for a finely controlled chemical
functionalization.
