Electronic structure of phosphorus dopants in ZnO

We study the defect properties of P dopants in ZnO through first-principles pseudopotential calculations. Because of the large size-mismatch between the P and O atoms, the acceptor level of a substitutional P (P O ) at an O lattice site is deeper than for N acceptors. A substitutional P (P Zn ) at a Zn antisite is found to be the dominant donor. Under Zn-rich condition, the P Zn donors are abundant, leading to n-type ZnO. As going to O-rich condition, Zn vacancies ( V Zn ) are energetically more favorable than the P O acceptors. Energy-lowering interactions between the P Zn defect and two Zn vacancies stabilizes the formation of a P Zn –2 V Zn complex, with a shallow acceptor level. This defect complex is suggested to be an important species in giving p -type ZnO together with the Zn vacancy.