P-type ZnO thin films prepared by in situ oxidation of DC sputtered Zn₃N₂:Ga

The feasibility of a new fabrication route for N and Ga codoped p-type ZnO thin films on glass substrates, consisting of DC sputtering deposition of Zn₃N₂:Ga precursors followed by in situ oxidation in high purity oxygen, has been studied. The effects of oxidation temperature on the structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance and Hall effect measurements. The results were compared to a control film without Ga. XRD analyses revealed that the Zn₃N₂ films entirely transformed into ZnO films after annealing Zn₃N₂ films in oxygen over 500 °C for 2 h. Hall effect measurements confirmed p-type conduction in N and Ga codoped ZnO films with a low resistivity of 19.8 Ω · cm, a high hole concentration of 4.6 × 10¹⁸ cm⁻³ and a Hall mobility of 0.7 cm²/(V·s). These results demonstrate a promising approach to fabricate low resistivity p-type ZnO with high hole concentration.