Optoelectronic properties of SnO_2 thin films sprayed at different deposition times

This article presents the elaboration of tin oxide (SnO₂) thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible (UV-Vis) transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction (XRD) patterns show that SnO₂ film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the (110) plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO₂ thin films are found to be in a range of 3.64 eV-3.94 eV. Figures of merit for SnO₂ thin films reveal that their maximum value is about 1.15×10^-4 Ω^-1 at λ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10^-2 Ω·cm.