The origin of p-type conductivity in P-doped ZnO

Abstract

Based on first-principles theoretical calculations, we investigate the electronic structure of various defects in P-doped ZnO. We find that a P-O impurity occupying an O site is a deep acceptor while a P-Zn atom at a Zn site is the dominant donor, causing a compenEation of acceptors. Under O-rich growth conditions, Zn vacancies (V-Zn) are the main source of p-type conduction. Since V-Zn is mobile and strongly interacts with abundant P-O and P-Zn defects, resulting complexes, such as P-Zn-2V(Zn) and P-O-V-Zn, which behave as acceptors, are likely to be formed under non-equilibrium growth conditions, and are responsible for the p-type conduction. We also investigate the effect of the strong Coulomb repulsion for the Zn d electrons on the electronic properties of various defects.