Origin of the high p-doping in F intercalated graphene on SiC

The atomic and electronic structures of F intercalated epitaxial graphene on a SiC(0001) substrate are studied by first-principles calculations. A three-step fluorination process is proposed. First, F atoms are intercalated between the graphene and the SiC, which restores the Dirac point in the band structure. Second, saturation of the topmost Si dangling bonds introduces p-doping up to 0.37 eV. Third, F atoms bond covalently to the graphene to enhance the p-doping. Our model explains the highly p-doped state of graphene on SiC after fluorination [A.L. Walter et al., Appl. Phys. Lett. 98, 184102 (2011)]. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3623484]