Built-in magnetic-electrical coupling enhances photocatalytic performance of GaN/ZnO: A first principle study

The electronic structure and transfer characteristic of holes and electrons of GaN/ZnO heterojunction polar interface with cation vacancy were calculated by first-principle. Results show that the defect levels induced by V-Zn, in Zn-N interface are made up of N-2p and O-2p states. The degeneracy of the defect levels and intrinsic CBM reduce the band gap of system. However, the defect level formed by the O-2p state may become a recombination center, which is not conducive to the separation of holes and electrons. In contrast, the defect level induced by V-G(a) in the Ga-O interface does not become a recombination center, and the larger built-in electric polarization intensity in the interface can effectively prevent the recombination of holes and electrons. In addition, the spin polarization of p states weakly bound electrons induced by cation vacancy leads to spin-band-splitting in the conduction band, which reduces the effective mass of electron and increases the transfer velocity difference between holes and electrons, so that photogenerated holes and electrons can be effectively separated.