N-doped ZnO thin films were prepared by atmospheric pressure mist chemical vapor deposition. The behaviors of H and N impurities were systematically studied, and a hydrogen-assisted nitrogen-doping mechanism was proposed to produce p-type ZnO. The H and N concentrations showed a linear correlation in as-grown samples. The p-type conductivity was realized by rapid thermal annealing in N-2 environment, with the hole concentrations typically of 10(17) cm(-3) at 475-500 degrees C. In this temperature window the dissociated hydrogen showed significant outdiffusion, while the nitrogen still remained stable in ZnO and behaved as effective acceptors resulting in good p-type conductivity. (C) 2007 Elsevier B.V. All rights reserved.