Optoelectronic Properties of Ag-Au Co-doped LiNbO3 Studied by First-Principles Generalized Gradient Approximation + U Approach

The electronic and optical properties of pure and Ag-Au co-doped lithium niobate crystals are calculated by using density functional theory (DFT). The obtained results indicate that lithium niobate exhibits a non-magnetic semiconducting nature. The co-doping percentage of 8.33% did not change the semiconducting nature of the crystal. However, a significant reduction in the band gap was found in the co-doped structure. For both pure and co-doped structures, the optical properties including dielectric function, refractive index, extinction coefficient, and reflectivity were calculated and thoroughly examined.