Fourier transformation infrared spectrum studies on the role of fluorine in SnO2:F films

In this letter we employed Fourier transform infrared spectroscopy (FTIR) to study fluorine-doped SnO2 films deposited by spray pyrolysis. The role of oxygen vacancy and substitution of fluorine for oxygen are demonstrated by FTIR. It is found that at low doping levels, fluorine ions prefer to occupy oxygen positions in SnO2 lattice. While beyond a certain doping level, fluorine ions start to occupy interstitial positions, which has a negative effect on carrier concentration that, in turn, affects the infrared reflectivity of SnO2 films. FTIR also shows the increase of the disorder of SnO2 films with increasing fluorine doping.