First principle investigation of electronic and optical properties of graphene/h-BN bilayers using Tran-Blaha-modified Becke-Johnson potential

We report ab initio DFT calculations to investigate the effect of the BN layer on the electronic and optical properties of graphene. The electronic properties of graphene/h-BN bilayers have been calculated with the Generalized Gradient Approximation (GGA) and modified Becke-Johnson (mBJ) exchange potential. This latter potential is used in the aims to improve the energy band gap value of graphene/h-BN bilayers. The dielectric function, the absorption spectrum and electron energy loss spectra (EELS) of graphene/h-BN bilayers have been evaluated for both parallel (//) and perpendicular (⊥) directions. Our results show a slight gap opening at K-point at the level of the Dirac cone in the graphene/h-BN bilayers band structure. In addition, the superposition of the boron nitride layer on the graphene causes opposite effects on EELS depending on the type of polarizations. Our comparison with the earlier studies shows that the BN-doped graphene gives a better gap value than the graphene/h-BN bilayers. However, the electronic and optical properties of graphene are also enhancing by adding a BN layer which can be promising for the application of bilayer graphene in nanotechnology.