The effect of precursor concentration and post-deposition annealing on the optical and micro-structural properties of SILAR deposited SnO₂ films

Uniform and well-adherent SnO₂ thin films, with thickness ranging from 60 nm to 6 μm, were deposited on borosilicate glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) technique. A micro-controlled SILAR unit was employed to precisely monitor the deposition conditions. The effect of precursor concentration and post-deposition annealing on the micro-structural and optical properties of SnO₂ thin films were studied in detail. The films were found to possess tetragonal rutile structure. The crystallite size of the films increased with solution molarity. Microstructural properties were analyzed using Scherrer, Modified Scherrer, Williamsons-Hall and Size-Strain plot techniques. Different optical properties such as band gap, skin depth, extinction coefficient, Urbach energy etc were determined. The post-deposition annealing at a moderate temperature of 573 K was found to enhance the crystallite size of the films while the density of the defect energy states reduced.