The relationship between processing and structural, optical, electrical properties of spray pyrolysed SnO2 thin films prepared for different deposition times

Abstract

Abstract SnO2 thin films were deposited on glass substrates at 350\u202f°C by spray pyrolysis technique for different deposition times (i.e. 4, 7, 10 and 13\u202fmin) from tin chloride (SnCl2, 2H2O). The X-ray diffraction analysis showed that all the synthesized films correspond to the tetragonal structure of SnO2. Depending on the deposition time, the estimated average crystallite size varied from 29 to 55\u202fnm using Williamson-Hall analysis (36 to 65\u202fnm using the Scherrer method). Atomic force microscopy analysis revealed homogenous surfaces with low values of roughness (9.9 to 27.7\u202fnm). As measured by spectroscopic ellipsometry, the thickness of the films was ranging from 150 to 350\u202fnm. The obtained SnO2 films displayed an average transmittance of 80% and a direct optical band gap ranging from 3.98 to 4.09\u202feV. The Hall-effect measurements revealed that all the films are conductive with values of conductivity varying from 32.3 up to 127 Ω−1.\u202fcm−1. From the obtained morphological, optical and electrical results, we conclude that spray pyrolysed tin oxide thin films are good candidates to be used in different fields, mainly in solar cell applications.