Structural and optical characterisation of undoped and chromium doped tin oxide prepared by sol–gel method

Transparent semiconductor thin films, Cr doped SnO2 (Sn1−xCrxO2: x = 0.0, 0.02, 0.04, 0.06, 0.10, 0.20) were deposited onto glass substrates by a sol–gel method. The thermal gravitational analysis showed that mass lost happened at 120 °C due to evaporation of water and ethanol. X-ray diffraction analysis showed that the Cr doped SnO2 were polycrystalline with SnO2 phases. The crystalline sizes were in the range of 3.7–4.9 nm. The optical property measured using UV-Vis spectrophotometer showed that the transparency of all samples was more than 90% and the calculated band gaps were in the range of 3.84–3.96 eV which was due to the Cr dopant that increased the samples energy band gap.