The influence of the post-deposition annealing (PDA) temperature and the use of different ambient gases on the structural and electrical properties of zinc oxide thin films grown by atomic layer deposition were investigated. The PDA did not change the optical properties of the films, but a slight improvement in the crystallinity was observed. The PDA strongly affected the electrical properties of the ZnO films. High-temperature annealing in air ambient led to the increase in resistivity, and high-temperature annealing in reducing N-2/H-2 ambient delayed such an increase. The increase in resistivity was correlated with the generation of deep-level trap states, as manifested by the increase of the red emission band centered at similar to 630 nm (similar to 1.97 eV) from photoluminescence. (C) 2014 Elsevier B.V. All rights reserved.