Realization of p-type ZnO thin films via phosphorus doping and thermal activation of the dopant

Abstract

A p -type ZnO was prepared on a sapphire substrate using P 2 O 5 as a phosphorus dopant. As-grown n -type ZnO films doped with phosphorus showed electron concentrations of 10 16 –10 17 / cm 3 and these films were converted to p -type ZnO by a thermal annealing process at a temperature above 800 ° C under a N 2 ambient. The electrical properties of the p -type ZnO showed a hole concentration of 1.0×10 17 –1.7×10 19 / cm 3 , a mobility of 0.53–3.51 cm 2 / V s , and a low resistivity of 0.59–4.4 Ω cm. The phosphorus-doped ZnO thin films showed a strong photoluminescence peak at 3.35 eV at 10 K, which is closely related to neutral acceptor bound excitons of the p -type ZnO. This thermal activation process was very reproducible and effective in producing phosphorus-doped p -type ZnO thin films, and the produced p -type ZnO was very stable.