Ab initio studies of isolated boron substitutional defects in graphane

Abstract

We have systematically studied energetics, structural and electronic properties of di erent con gurations of the B atoms substituting C-H pairs located on a single hexagonal ring in a graphane system using the rst-principles density functional theory (DFT). A total number of 12 distinct B dopants con gurations were identi ed and characterized. Based on the formation energy analysis, we found that relative stability of B dopants depends greatly on the defect con gurations. Our results suggest that the B substitutions prefer to be distributed randomly but avoiding the formation of homo-elemental B-B bonds in a graphane system, at any concentration. Generally, the values of band gap decrease as the number of B dopants increases, but the low energy con gurations have large band gaps compared to those that have homo-elemental bonds. As a result, the band gap of graphane can be ne tuned through the change in the structural arrangement of B atoms. The adequate control of the electronic structure of graphane through doping should be essential for technological device applications.