Preparation and characterization of crystalline Ba0.5Sr0.5TiO3 thin films on FTO transparent electrodes

Abstract

To achieve an economic advantage, nanocrystalline Ba0.5Sr0.5TiO3 (BST) thin films were prepared on FTO-coated glass substrates using an aqueous sol–gel process. The crystal structures and chemical states of the obtained thin films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD patterns confirmed the perovskite structure of the BST samples, while XPS analysis demonstrated that Ba element was in its single oxidation state in the film with annealing temperature of 600 °C. In contrast, Ba was present in a mixed oxidation state upon increasing the annealing temperature. It was found that the BST thin film prepared at a relatively low annealing temperature of 600 °C exhibited optimal crystallinity and superior dielectric properties, along with excellent optical transparency. More specifically, this film exhibited a dielectric tunability of 44.81% (1.33 MV/cm), a figure of merit of 56.01, and an average transmittance of 87.2% in the visible region.