EFFECT OF THICKNESS ON MICROSTRUCTURE, DIELECTRIC AND OPTICAL PROPERTIES OF SINGLE LAYER Ba_0.6Sr_0.4TiO₃ THIN FILM

Abstract

Single layered Ba 0.6 Sr 0.4 TiO 3 (BST) thin films were prepared on stainless steel (304) and quartz substrates by solution method. The microstructure, grain size, surface morphology and thickness of the films were reported on the basis of X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and UV-visible spectrometer. Variation in thickness influences the microstructure of the films. The single layered thin film had uniform crack-free surface morphology. The low frequency dielectric constants for the films of thicknesses 663, 476 and 451 nm were found to be 1246, 859 and 703, respectively at room temperature. The dielectric loss values for different thicknesses were found to be 0.238%, 0.170% and 0.120% for 100 kHz and 0.043%, 0.029 % and 0.028% for 1 kHz. The dielectric properties changed significantly with thickness of the film as well as with frequency. The tunability of the single layered BST film increased with film thickness. The refractive index, bandgap and thickness of the single layered thin film were calculated by using envelope method and Tauc's relation from the UV-visible transmission spectrum. The bandgap increases with the film thickness. These results show that this single layered film will be a potential material for tunable devices application.