Structural and electrical properties of fluorine doped tin oxide films prepared by spray-pyrolysis technique

Fluorine doped SnO2 films have been successfully prepared at optimized substrate temperature of 723 K by spray pyrolysis technique. The XRD analysis confirmed that films deposited with F/Sn ratio of 0.05 showed a partial amorphous nature whereas films deposited with F/Sn = 0.10 exhibited tetragonal structure (2 0 0) as the preferred orientation and polycrystalline structure. The lattice constants were found to be a = 0.4750 and c = 0.3197 nm. The theoretically constructed XRD pattern for SnO2 was used to compare with experimental pattern, the difference between them is discussed. By using SEM analysis, the surface morphology of the films was observed as an effect of the variation of F/Sn ratio. At low temperature, the mobility due to lattice, polar, impurity, grain boundary and neutral scattering was estimated for SnO2 and the possible scattering mechanisms were assigned to SnO2:F films using experimentally obtained electrical data. The Mott parameters were determined by applying variable range hopping (VRH) conduction mechanism for SnO2:F films (F/Sn = 0.05) where band conduction mechanism shifted to VRH conduction at below about 250 K.