Improvement of electrical and optical properties of Ga and N co-doped p-type ZnO thin films with thermal treatment

Ga and N co-doped p-type ZnO thin films were epitaxially grown on sapphire substrate using magnetron sputtering technique. The process of synthesized Ga and N co-doped ZnO films was performed in ambient gas of N2O. Hall measurement shows a significant improvement of p-type characteristics with rapid thermal annealing (RTA) process in N2 gas flow, where more N acceptors are activated. The film rapid thermal annealed at 900 °C in N2 ambient revealed the highest carrier concentration of 9.36 × 1019 cm−3 and lowest resistivity of 1.39 × 10−1 Ω cm. In room and low temperature photoluminescence measurements of the as grown and RTA treated film, donor acceptor pair emission and exciton bound to acceptor recombination at 3.25 and 3.357 eV, respectively, were observed.