The effect of Al and Zn Co-doping on the structural, electrical and optical properties of SnO₂ thin films have been studied. The undoped and aluminium and zinc co-doped SnO₂ nano crystalline thin films were prepared on glass substrates at 400 °C by spray pyrolysis technique. The starting material is (SnCl₄.5H₂O) and doping source are aluminium chloride and zinc chloride for tin (Sn), aluminium (Al) and zinc (Zn) respectively. The source materials have been dissolved in ethanol and stirred for four hours at 50 °C. The doping stoichiometric ratio was 4%. The resulting solution was sprayed on glass substrate which was kept at nozzle distance of 25 cm and the spray rate was 10 mL/min. The prepared pure SnO2 thin film, Al and Zn Co-doped SnO₂ thin films have been characterized by different methods such as XRD, FESEM, UV-Vis NIR and EDAX analyses. The obtained results suggested that the prepared nanocrystalline thin films are suitable for gas sensor applications

Keywords: Al - Zn Co-doped SnO₂; Thin Films; Spray Pyrolysis; Nanocrystalline;