Optical properties and electrical characterization of p-type ZnO thin films prepared by thermally oxiding Zn₃N₂ thin films

In this paper, we report a simple method for preparing p-type ZnO thin films by thermal oxidization of Zn₃N₂ thin films. The Zn₃N₂ films were grown on fused silica substrates by using plasma-enhanced chemical vapor deposition from a Zn(C₂H₅)₂ and NH₃ gas mixture. The Zn₃N₂ film with a cubic antibixbyite structure transformed to ZnO:N with a hexagonal structure as the annealing temperature reached 500 °C. When the annealing temperature reached 700 °C, a high-quality p-type ZnO film with a carrier density of 4.16 × 10¹⁷ cm⁻³ was obtained, for which the film showed a strong near-band-edge emission at 3.30 eV without deep-level emission, and the full width at half-maximum of the photoluminescence spectrum was 120 meV at room temperature. The origin of the ultraviolet band was the overlap of free exciton and the bound exciton. The N concentration was as high as 10²¹ cm⁻³, which could be controlled by adjusting the parameters of the annealing processes.