Electrical properties of ZnO:A1 films deposited on glass substrates by RF magnetron co-sputtering method have been modified by post-deposition annealing treatment in hydrogen atmosphere for potential transparent conductive oxide (TCO) applications. Annealing treatments were carried out at 573K for compatibility with typical display device fabrication processes and annealing time was varied between 10 and 120 min. Whereas there were no significant changes in crystallinity of the films, resistivity decreased from 4.80 x 10(-3) to 8.30 x 10(-4) Omega cm and carrier concentration increased from 2.11 x 10(20) to 8.86 x 10(20) cm(-3) when annealing time was 60 min. Improved electrical properties are ascribed to desorption of the negatively charged oxygen species from the grain boundary surfaces by the hydrogen annealing treatment. The optical properties of the films, which change in accordance with the Burstein-Moss effect, are consistent with the observed changes in electrical properties. (c) 2005 Elsevier B.V. All rights reserved.