Electrical characterization of p-type N-doped ZnO films prepared by thermal oxidation of sputtered Zn3N2 films

We report on p-type conduction in N-doped ZnO (ZnO:N) films that were prepared by oxidative annealing of sputtered Zn3N2 films at temperatures between 500 and 800°C in flowing O2 gas. Room-temperature Hall-effect measurements show a significant improvement of p-type doping characteristics by the oxidative annealing at temperatures between 700 and 800°C, where more N acceptors are activated and the oxidation state is enhanced, as confirmed by deep-level optical spectroscopy and secondary ion mass spectrometry measurements. Therefore, the high-temperature oxidation of Zn3N2 is effective in moderating the self-compensation effect in ZnO:N from the viewpoint of oxygen vacancy annihilation.