Effect of Spin Coating Parameters on Optical and I–V Characteristics of Fe2O3 Thin Films

Iron oxide (Fe₂O₃) thin films were successfully prepared on glass substrates using a simple and cost-effective spin coating technique to study the influence of spin speed on their optical and electrical properties. A 0.5 M ferric chloride (FeCl₃) precursor solution was used for deposition, and films were coated at 2500 rpm and 3000 rpm for 60 s. The deposited films were annealed at 600 °C for 5 h to obtain the crystalline hematite (α- Fe₂O₃) phase with improved structural stability. Optical properties were analysed using UV–Visible spectroscopy, which revealed strong absorption in the visible region along with good transparency at longer wavelengths. The optical band gap, estimated from Tauc plots, was found to range between 1.84 and 1.90 eV, indicating that spin speed influences film thickness and microstructural uniformity. Electrical characterization was carried out through current–voltage (I–V) measurements in the voltage range of 0–14 V at room temperature. The films exhibited semiconducting behaviour with nearly ohmic conduction at lower voltages. The film deposited at 3000 rpm showed higher current and lower resistance compared to the 2500 rpm film, suggesting enhanced crystallinity and improved charge carrier mobility. These findings confirm the significant role of spin coating parameters in tailoring Fe₂O₃ thin films for optoelectronic and energy-related applications