Effects of annealing ambience on ZnO:N films grown by MOCVD and the p-type doping mechanism of ZnO:N films investigated by XANES

ZnO:N thin films were deposited on sapphire substrate by metal organic chemical vapor deposition with NH3 as N-doping sources. The reproducible p-type ZnO:N film with hole concentration of ∼1017 cm−3 was successfully achieved by subsequent in situ thermal annealing in N2O plasma protective ambient, while only weak p-type ZnO:N film with remarkably lower hole concentration of ∼1015 cm−3 was obtained by annealing in O2 ambient. To understand the mechanism of the p-type doping behavior of ZnO:N film, X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption near-edge spectroscopy (XANES) measurements have been applied to investigate the local electronic structure and chemical states of nitrogen atoms in ZnO:N films.