Investigation of diffusion and crystallization processes in thin ITO films by temperature and time resolved grazing incidence X-ray diffractometry
Oxygen diffusion into metallic In/Sn films and crystallite growth of thin indium tin oxide (ITO) films were investigated by in situ high temperature grazing incidence X-ray diffractometry (HT-GIXRD) at temperatures ranging from 100 to 300 °C. The investigated films were deposited by dc magnetron sputtering from a metallic target at different oxygen flows and bias voltages. The deposition process influences not only the film properties but also the film reactions during the post-deposition annealing process. The ITO formation is determined by two processes: the diffusion of oxygen into the metallic grains and a fast crystallization process. Kinetic parameters for both processes were derived. A model was developed which allows the determination of the diffusion coefficient D from the time dependence of the integral intensity of the ITO X-ray reflection. Diffusion coefficients as well as the activation energies are influenced by the bias voltage but not by the oxygen flow. According to the Johnson–Mehl–Avrami theory, the crystallization can be described as a two-dimensional process.