Thin Sn-doped In films were deposited by direct-current magnetron sputtering at various substrate voltages. The metallic films were annealed in a high-temperature vacuum chamber (10-5mbar) and studied by using in situ grazing-incidence X-ray diffractometry. During post-deposition annealing, crystalline indium tin oxide formed in a diffusion-limited process. A mathematical model was used to derive the effective diffusion coefficients Deff from the time dependence of the indium tin oxide (222) X-ray reflection integral intensity. A strong influence of the bias voltage on Deff was observed. From the temperature dependence of the diffusion coefficients, the activation energy values for O diffusion into the metallic films were calculated. To understand the differences in Deff, the microstructure of the as-deposited films was investigated. Information on domain sizes, micro-strains and dislocation densities was obtained from X-ray profile analysis using the Warren–Averbach and Krivoglaz–Wilkens methods. A distinct change in grain size was found, depending upon the negative substrate voltage used. With respect to the film properties, the contribution of mass transport along grain boundaries, as well as through the lattice and dislocation cores, on the effective diffusion coefficient could be separated. It was shown that Deff was influenced mainly by grain boundary diffusion, whereas diffusion within the grains largely determined the activation energy for the process

Influence of Microstructure on Oxygen Diffusion in Plasma-Deposited In/Sn Films. M.Quaas, H.Steffen, R.Hippler, H.Wulff: Thin Solid Films, 2002, 420-421, 306-11