Influence of thermal annealing on the Band-Gap of tio2 thin films produced by the Sol-Gel method

Abstract

In our study, we used the spin coating method to produce TiO2 thin films on quartz glass using a solution with a concentration of 0.5M. After the coating process, the samples were dried in air at 100°C. Subsequently, annealing was carried out at four different temperatures, namely 300°C, 500°C, 700°C, and 900°C, for a duration of 60 minutes. Comprehensive analyzes including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD) and optical measurements were carried out to investigate the structural and optical properties of the samples. Optical measurements showed that the highest average transmittance values were obtained for samples annealed at 300°C and 500°C, with percentages of 82.33% and 80.25%, respectively. Remarkably, the maximum transmittance of 99.58% was recorded for films annealed at 500°C. Additionally, band-gap calculations were performed using the Tauc method based on optical measurements of samples exposed to different annealing temperatures. According to our results, samples annealed at 300°C, 500°C, 700°C, and 900°C exhibited band-gap values of 3.42eV, 3.40eV, 3.38eV, and 3.29eV, respectively.