Investigation on the p-type formation mechanism of nitrogen ion implanted ZnO thin films induced by rapid thermal annealing

Abstract

N-doped p-type zinc oxide (ZnO) thin films were prepared by rapid thermal annealing (RTA) of nitrogen ion implanted high quality ZnO epitaxial layers. Annealing at 900 °C in a nitrogen atmosphere leads to the conversion of conductivity from n to p-type with a hole concentration of 9.60×1017 cm-3, which is reflected in photoluminescence spectra. To reveal the thermal activation and doping mechanism of this film, the samples were also analyzed by Raman scattering and X-ray photoelectron spectroscopy. The results indicate that elimination of the Zni related shallow donors and the formation of shallow acceptor complex No-VZn account for the stable p-type conductivity of N-doped ZnO. The shallow acceptor state is calculated at 0.161 eV above the valence band edge.