Effect of the Electric Field on the Electronic and Optical Properties of the Bilayer Graphene, Bilayer Boron Nitride and Graphene/Boron Nitride

In this study, we have investigated the effect of the external electric field on the electronic and optical properties of the AB stacked bilayer graphene, bilayer boron nitride and bilayer graphene/boron nitride utilizing the DFT. The results have shown that in the presence of the external electric field, the electronic properties of all structures have been changed and their energy gaps are tunable in this way. Exerting the electric field on the bilayer graphene structure, its energy dispersion relation is changed and the parabolic shape of the bands at the K-point is changed to a new form called the "Mexican Hat". The presence of an electric field of magnitude 1 V/Ang increases the energy band gap of this structure and ultimately reaches 0.28 eV. However, exerting field and increasing its intensity reduced the energy band gap of the boron nitride bilayer, such that in the presence of a field of intensity 3.5 V/Ang, the energy band gap decreases by 88% and reaching about 0.53 eV. Also, we see the semiconductor-metal transition for this structure in the presence of stronger fields. Due to exerting the field, the band gap of the graphene/boron nitride bilayer increased with less intensity and the bands maintains their parabolic shape in the K point. Finally, the effect of electric field on the optical diagrams of these structures is investigated. Applying the external electric field on these structures changes the magnitude and location of the optical diagram peaks. To investigate this, we have applied only the perpendicular polarization. As a consequence of the presence of an external electric field, an increase in the static dielectric function is visible for all three structures. It is also observed that the application of the electric field also affects the plasmonic behavior of the systems.