H2/Ar and vacuum annealing effect of ZnO thin films deposited by RF magnetron sputtering system

The properties of ZnO films were investigated as functions of annealing temperatures in H2/Ar and vacuum. The resistivities and mobilities of ZnO films decreased with increase of annealing temperatures in vacuum and H2/Ar ambients. However, the carrier densities of ZnO films increased with increase of annealing temperatures in vacuum and H2/Ar ambients. The resistivities of ZnO2 films annealed at 300 °C were ∼2186 Ω cm and ∼798 Ω cm in H2/Ar and vacuum ambients, respectively. The resistivities of ZnO films annealed in vacuum and H2/Ar ambients at 600 °C were similar with ∼0.040 Ω cm and ∼0.035 Ω cm, respectively. The hydrogen donor was more dominant than the oxygen vacancy or Zn interstitial donor in ZnO films annealed in ambient H2/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 H2/Ar ambients.