Structural and optical parameters of sol-gel derived Barium Strontium Titanate (BST) thin film

Barium Strontium Titanate thin film was fabricated successfully on a corning glass substrate via sol-gel process technique. The as-prepared film was found to be amorphous, which crystallizes after annealing at different temperatures (500 °C, 550 °C). The influence of annealing temperature on the structural and optical properties of the fabricated thin films was analyzed. The XRD data reveals that the samples have a cubic structure with preferred orientation along (1 1 0) plane. Ultraviolet–Visible spectroscopy technique was used to determine various optical parameters such as transmittance, extinction coefficient (k), optical band gap, refractive index (n), and Urbach energy of the fabricated thin films. The optical bandgap of the crystalline sample decreased from 3.52 eV to 3.41 eV with the increase in annealing temperature. Optical transmittance spectra in the wavelength range 300 ∼ 1100 nm show good optical transparency of the BST thin film. The variation of the extinction coefficient and refractive index as a function of frequency has been discussed and reported. Optical parameters of the prepared thin film suggest its potential application in optoelectronic devices.