Correlation between diffraction patterns and surface morphology to the model of oxygen diffusion into ITO films

Indium tin oxide (ITO) films post-annealed in air usually have higher resistivity compared to the ITO films post-annealed in vacuum. This is likely due to the incorporation of oxygen atoms into the ITO films during post-annealing treatment in air. In this paper, we studied mainly the electrical properties of ITO films as a function of post-annealing temperature and post-annealing ambient. Our results show that the ITO films post-annealed in vacuum have lower resistivity compared to the ITO films post-annealed in air. From the results, we relate the model of oxygen diffusion with the AFM images and the (4 0 0)/(2 2 2) XRD peak ratio. We observe that the ITO films post-annealed in vacuum have larger grain size through the AFM images. The reduction of grain boundary scattering leads to higher conductivity. Furthermore, the ITO films post-annealed in vacuum have rather constant (4 0 0)/(2 2 2) XRD peak ratio. This result indicates that there is less oxygen atoms diffuse into the ITO films in vacuum. The ITO film post-annealed at 500 °C in vacuum has a grain size of ∼125 nm and resistivity of ∼3.49 × 10−4 Ω cm.