Investigations on the electronic structure and optical properties of (Ga, N,Ga-N) doped graphene by first-principle calculations

The optical and electronic properties of pure graphene, nitrogen doped graphene, gallium doped graphene and nitrogen and gallium co-doped graphene were researched based on the first-principle method of density functional theory (DFT). Pure graphene has a zero-band structure, and when doped in graphene, its bands are opened. In this study, the bandgap of N-doped graphene was 0.20 eV, Ga-doped graphene was 0.35 eV and N-Ga co-doped graphene was 0.49 eV. They also have different electron density. In the N-Ga co-doped graphene, the N atom gained more electrons (-0.6 1e) than the N-doped graphene (-0.27 e), and the Ga atom lost more electrons (1.80 e) than the Ga-doped graphene (1.75 e). Moreover, the optical properties of pure graphene and doped graphene were analyzed and compared. These properties include complex refractive index, dielectric function and light absorption. From these analysis results, it can be seen that the doping study in graphene has effectively improved the optical and electrical properties of graphene. This study provides an effective theoretical foundation for the future development of graphene-based photoelectric devices.