Influence of annealing in N2 on the properties of In2O3:Sn thin films prepared by direct current magnetron sputtering

In2O3:Sn (ITO) films were deposited on quartz substrates by direct current magnetron sputtering and annealed in N2 at temperatures ranging from 150 to 350 °C for 1 h. The structure and morphology of the films were investigated by X-ray diffraction and atomic force microscopy. The results demonstrate that the as-deposited films are polycrystalline structure and the crystallinity can be apparently improved after annealed above 250 °C. The electrical and optical properties of the films were also studied by van der Pauw method and spectrophotometer, respectively. It is found that the carrier concentration increases and mobility decreases, respectively, after the films have been annealed at high temperature. As a consequence, the resistivity changes from 14.80 × 10−4 Ω cm for the as-deposited film to 3.99 × 10−4 Ω cm for the film annealed at 350 °C. Furthermore, even the optical absorption in the near-infrared region increases for the annealed films, the high quality of transmittance (more than 90%) within the visible region can be retained. The measured transmittance data were also simulated very well based on the modified Drude and Forouhi-Bloomer models. Additionally, the electrical parameters calculated from the optical simulation, such as carrier concentration, mobility, and resistivity, are in good agreement with those obtained electrically by van der Pauw method.