Effect of Preparation Temperature on the Microstructure and Physical Properties of Chemically Deposited SnO₂ Thin Films

Abstract

In this work, tin dioxide (SnO₂) thin films were prepared by thermochemical decomposition method with different deposition temperature (325°C to 375°C)) using the precursor concentrations of 0.02 M. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–Visible spectroscopy, and Hall effect measurements were conducted on films, to comprehensively evaluate their structural, optical, and electrical properties and the effect of temperature. Increasing deposition temperature leads initially to improved crystallinity and surface uniformity with optimal microstructural quality being reached at 350 °C with subsequent degradation at 375 °C due to increased lattice disorder and increasing lattice strain. The enhanced transmittance with and widening of the band gap (with increasing temperature) due to reduced film thickness and porosity were supported by optical characterization. Electrical measurements indicate that films fabricated at 350 °C possess the highest carrier mobility and electrical conductivity despite low carrier concentrations. These results show that the best compromise between structural order and charge transport efficiency is achieved at 350 °C. This study shows great promise in understanding how to tune the physical properties of SnO₂ thin films by controlling the thermal process, and their potential for opto-electronic and sensing applications.