Evolution of element distribution at the interface of FTO/SiOxCy films with X-ray photoelectron spectroscopy

•The effect of diffusion on the conductivity has been proved experimentally.•The value of [O]/[Sn] in the middle layer is about 1.21.•The middle layer may effect a little on the film conductivity.•There are some interstitial Sn atoms in the diffusion layer.•The exacerbated diffusion at the interface makes the conductivity decreased.

X-ray photoelectron spectroscopy was carried out to investigate the element distribution along the film depth, especially at the interface of FTO/SiOxCy films as-deposited and post-treated at 700 °C for 202 s and 262 s in the tempering furnace. The results show that the middle layer may effect a little on the conductivity, while an important diffusion layer exists between the functional layer and the barrier layer. It has been proved experimentally that the exacerbated diffusion at the interface layer makes the conductivity decreased.