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 N-2 gas flow, where more N acceptors are activated. The film rapid thermal annealed at 900 degrees C in N-2 ambient revealed the highest carrier concentration of 9.36 x 10(19) cm (3) and lowest resistivity of 1.39 x 10 (1) Omega 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. (C) 2008 Elsevier B. V. All rights reserved.