“…Undoped ZnO is usually n-type conductive, which is associated with the presence of native point defects (e.g., oxygen vacancies (V O ) and interstitial zinc (Zn i )) [4] or hydrogen impurities [5], but the fabrication of stable and reproducible p-type ZnO has been difficult due to the self-compensation and low solubility of acceptor dopants. In recent years, several groups have reported the growth of p-type ZnO by doping group V elements N [6,7], P [8], As [9] and Sb [10]. Among the group V elements, nitrogen has been regarded as the most suitable dopant for p-type ZnO due to its similar atomic radius to that of oxygen.…”