Structural and Optical Characterization of Tin Oxide Codoped with Aluminum and Sulphur

Abstract

Thin films of Tin oxide co-doped with 28at%Aluminum and varied concentration of Sulphur were prepared on 1mm thick, 1 × 1 cm2 glass substrates at 470℃ by spray pyrolysis technique. Films were produced from 2.0 M solution of hydrous tin chloride dissolved in ethanol with 38% hydrochloric acid concentration, 1.5M aqueous Aluminum chloride and 2.0M aqueous solution of AmoniumSulphide. Effects of Sulphur concentration on structural and optical properties of transparent Tin Oxide thin films were investigated in the Sulphur content range (0-50) at% with a fixed 28at%Al content. Structural and optical characterization of films was measured with Siemens D5000 X-ray diffractometer and Perkin-Elmer Lambda 900 double beam spectrophotometer respectively. Dispersion analysis based on a model of Drude and Kim terms was used to simulate the experimental transmittance and reflectance data. Films with thickness lying in the range 171nm-247nm were analyzed. Polycrystalline structures without any second phases were observed with preferential orientations along the (110), (101), (200) and (211) planes. Average grain size as determined from the (110) peaks lay in the range 19.2nm-47.7 nm. Optical band gaps lay in the range 3.93-4.02eV. It was observed that co-doping lowered the grain size significantly and increased transparency of the oxide