Effect of substrate temperature on the properties of Bi2O3 thin films grown by sol-gel spray coating

Abstract

Bi2O3 thin films have been successfully deposited on glass substrate by sol-gel spray coating technique at different temperatures between 150 °C and 550 °C using bismuth nitrate pentahydrate as raw material. Thin films were then annealed at a temperature of 350 °C. This study aims to analyze the effect of substrate temperature on the structural, morphological, topological, and optical properties by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and UV–Vis Spectroscopy. The diffraction peak position of XRD showed that the as-obtained Bi2O3 thin films were crystalline and different substrate temperatures played a key role in the phase transition β→δ-Bi2O3. The morphology and topology of Bi2O3 show different results which are highly influenced by substrate temperatures whereas Bi2O3 thin film at 450 °C has the highest value of surface roughness. The skewness and kurtosis were also investigated. The optical study showed the band gap energy values of the as-obtained Bi2O3 thin film varied at different substrate temperatures between 2.35 eV and 2.78 eV.