The properties of ZnO films were investigated as functions of annealing temperatures in H-2/Ar and vacuum. The resistivities and mobilities of ZnO films decreased with increase of annealing temperatures in vacuum and H-2/Ar ambients. However, the carrier densities of ZnO films increased with increase of annealing temperatures in vacuum and H-2/Ar ambients. The resistivities of ZnO2 films annealed at 300 degrees C were similar to 2186 Omega cm and similar to 798 Omega cm in H-2/Ar and vacuum ambients, respectively. The resistivities of ZnO films annealed in vacuum and H-2/Ar ambients at 600 degrees C were similar with similar to 0.040 Omega cm and similar to 0.035 Omega cm, respectively. The hydrogen donor was more dominant than the oxygen vacancy or Zn interstitial donor in ZnO films annealed in ambient H-2/Ar at low temperatures. The average optical transmission was > 82% and an orientation of the deposition was [0 0 2] for all ZnO films annealed in vacuum and H-2/Ar ambients. (C) 2010 Elsevier B. V. All rights reserved.