High-quality spray-deposited fluorine-doped tin oxide: effect of film thickness on structural, morphological, electrical, and optical properties

High-quality fluorine-doped tin oxide (FTO) thin films were deposited using a low-cost homemade spray pyrolysis apparatus and the effect of film thickness on structural, morphological, electrical, and optical properties were investigated. As the thickness increases, the carrier concentration remains almost unchanged (similar to 2.6 x 10(20) cm(-3)). However, as a result of grain size increase, mobility enhanced considerably (from 19.1 to 40.1 cm(2) V-1 s(-1)), which can be a convincing explanation for resistivity reduction (from 12.0 x 10(-4) Omega cm to 6.00 x 10(-4) Omega cm). As expected, the FTO thin films were highly transparent in the visible region and naturally decreased by increasing the thickness. The band-gap value of the spray-deposited FTO thin films was estimated, with results showing a gradual reduction with increasing thickness. The figure of merit was calculated for the prepared FTO thin film and an outstanding value of 9.77 x 10(-3) Omega(-1) corresponding to an average transmittance of 78.60 (400-900 nm) and sheet resistance of 9.21 Omega/sq was achieved.