Transformation of metallic boron into substitutional dopants in graphene on 6 H − SiC ( 0001 )

We investigate the development of the local bonding and chemical state of boron atoms during the growth of B-doped graphene on 6H -SiC(0001). Photoemission experiments reveal the presence of two chemical states, namely, boron in the uppermost SiC bilayers and boron substituted in both the graphene and buffer layer lattices. We demonstrate the participation of the dopant in the π electron system of graphene by the presence of the π ∗ resonance in the near edge x-ray adsorption fine structure (NEXAFS) recorded at the B K-edge. The experimental findings are supported by NEXAFS simulations.