Electronic structures of an epitaxial graphene monolayer on SiC(0001) after goldintercalation: a first-principles study

Abstract

The atomic and electronic structures of an Au-intercalated graphene monolayer on theSiC(0001) surface were investigated using first-principles calculations. The unique Diraccone of graphene near the K point reappeared as the monolayer was intercalated by Auatoms. Coherent interfaces were used to study the mismatch and the strain at theboundaries. Our calculations showed that the strain at the graphene/Au and Au/SiC(0001)interfaces also played a key role in the electronic structures. Furthermore, we found that atan Au coverage of 3/8 ML, Au intercalation leads to a strong n-type doping of graphene. At9/8 ML, it exhibited a weak p-type doping, indicative that graphene was not fullydecoupled from the substrate. The shift in the Dirac point resulting from the electronicdoping was not only due to the different electronegativities but also due to the strain at theinterfaces. Our calculated positions of the Dirac points are consistent with thoseobserved in the ARPES experiment (Gierz et al 2010 Phys. Rev. B 81 235408).