Stability and electronic properties of isomers of B/N co-doped graphene

Abstract

We study and compare some of the possible isomers of BN co-doped graphene on the basis of their composition and electronic properties. The effect of doping has been studied theoretically by substituting the C atoms of graphene with an equal amount of B/N with their concentration varying from 4 % (2 atoms of the dopant in 50 host atoms) to 24 % and choosing different doping sites for each concentration. We made use of VASP (Vienna Ab-initio Simulation Package) software based on density functional theory to perform all calculations. While the resulting geometries do not show much of distortion on doping, the electronic properties show a transition from semimetal to semiconductor with increasing number of dopants as in the case of individual B and N doping. The study shows that the BN doping introduces the band gap at the Fermi level unlike individual B and N doping which causes the shifting of Fermi level. High value of the cohesive energy indicates the stability of the resulting heterostructures. Isomers formed by choosing different doping sites differ significantly in relative stability and band gap introduced and these aspects, to a great extent, depend upon position of B and N atoms in the heterostructure.