Study on the Effect of Thickness on Structural and Optical Properties of Nanocrystalline Bismuth Ferrite (BiFeO<sub>3</sub>) Thin Films

Abstract

Nanocrystalline Bismuth ferrite (BiFeO3) thin films of different thickness were deposited on glass substrates using sol-gel processing technique. The effect of thickness on structural and optical properties of BiFeO3thin films has been studied. The as-fired films were found to be amorphous that crystallized to hexagonal structure after annealing at 500°C for 2hr in air. The XRD pattern shows that the samples are polycrystalline in structure. At low annealing temperature (400°C), the thick film samples show amorphous in nature while thinner film shows some crystallinity with the presences of impurity phases. At high annealing temperature, all the samples show single phase distorted perovskite BiFeO3structure. The AFM photograph reveals that there is an increase in the grain size with the increase in film thickness. Optical transmittance spectra shows that, with the increase in film thickness, there is a decrease in transmittance (T%). Further, it is observed that increase in film thickness would lead to the decrease in optical energy band gap of the samples. The effect of thickness on the photoluminescent properties of BiFeO3films have also been studied for their possible application in nanoscale optoelectronic devices.