Ab initio study of Ge intercalation in epitaxial graphene on SiC(0001)

We study within a van der Waals density functional theory framework the structural and electronic properties of Ge-intercalated epitaxial graphene on SiC(0001). We argue that the insertion of Ge adatoms at the graphene/SiC interface results in an almost complete detachment of the graphitic layer from the substrate. A stable electron-doped phase is obtained as a result of the pinning of the Fermi level by sp 3-type Ge danglingbond states. Stability is preserved when germanium atoms substitute Si/C atoms of the SiC substrate, while it is compromised when Ge is additionally chemisorbed on the graphene surface. Results are in good agreement with recent experiments. © 2011 The Japan Society of Applied Physics.