Characterization of SnO2 Thin Films deposited with SILAR: Effect of Annealing on Physical Properties

SnO₂ thin films were deposited on glass substrates using the SILAR method at room temperature and subsequently annealed at 250 °C, 300 °C, and 350 °C for 30 min. The structural, morphological, and optical properties of the as-grown and annealed films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDAX), atomic force microscopy (AFM), and UV–Vis spectroscopy. XRD analysis revealed that increasing the annealing temperature improved crystallinity, enhanced peak intensities, and promoted the formation of the rutile SnO₂ phase. SEM and AFM analyses showed that annealing led to grain growth and smoother film surfaces. EDAX confirmed the presence of Sn and O elements, while the Si signal from the substrate decreased at higher annealing temperatures due to improved surface coverage. UV–Vis measurements indicated a reduction in optical band gap from 3.53 eV (as-grown) to 3.21 eV (350 °C), attributed to enhanced crystallinity and reduced structural defects. The results of this study demonstrate the strong influence of annealing temperature on the structural and optical performance of SILAR-grown SnO₂ thin films, which directly determines their suitability for optoelectronic devices. The enhanced crystallinity and increased crystallite size observed after annealing improve charge carrier mobility by reducing grain boundary scattering. This is particularly beneficial for applications such as transparent conducting electrodes, gas sensors, and thin-film transistors, where high electrical conductivity and structural order are essential. © The Author(s) under exclusive licence to Sociedade Brasileira de Física 2026.