First-principles study on electronic and magnetic properties of N mono-doped and (N, Co) co-doped ZnO

Abstract Using first principles calculations based on the density functional theory and local spin density approximation, we predict magnetic and electronic properties of N mono-doped and (N–Co) co-doped ZnO for different dopants concentration. The results show that ZnO doped with N concentration of 12.5% is p-type, semi-metallic and ferromagnetic due to the strong hybridization effect between N 2p and O 2p states, with a total magnetic moment of 1 μ B mainly arises from N 2p orbitals. Nevertheless we find a deep and narrow acceptor level, resulting in large acceptor ionization energy of ZnO (N). With increasing N concentration to 25% we find that the impurity energy level is shallow and shifts downward to the direction of low energy, consequentially, the acceptor binding energy is reduced. (N–Co) co-doped ZnO with a concentration of 12.5% for the two dopants is p-type and half-metallic with an important magnetic moment of 3.98 μ B , due to Co 3d and N 2p states.