First-principles study of the effects of Li/Na/K doping and point defects on the magnetic and photocatalytic properties of monolayer GaN (0 0 1)

Abstract

In the experimental preparation of monolayer GaN (0 0 1) by chemical-vapor deposition, H impurities inevitably remain, and the intrinsic defect VGa inevitably forms. In this research, generalized gradient approximation + U plane-wave ultrasoft pseudopotentials are computed using the density-functional theory framework. The effects of Li/Na/K doping and point defect (Hi-VGa) coexistence on the magnetic properties and photocatalytic properties of monolayer GaN (0 0 1) surfaces are investigated. Results show that the monolayer Ga34MN36 (M = Li/Na/K) (0 0 1) surfaces are magnetic, and the source of its magnetism is primarily the itinerant electrons of N2− ions. The monolayer Ga34MHiN36 (0 0 1) surfaces are relatively more stable, and the separation degree of carriers is better than the monolayer Ga34MN36 (0 0 1) surfaces. In particular, the monolayer Ga34LiHiN36 (0 0 1) surface has a large electric-dipole moment, strong carrier activity, strong absorption efficiency, and strong oxidation-reduction properties. Therefore, the monolayer Ga34LiHiN36 (0 0 1) surface is the most suitable photocatalyst.