Tuning leakage current and ferroelectric properties in spin-coated BiFeO3 films through Cr doping and post-annealing atmosphere control

Effective enhancement of ferroelectric properties in BiFe1-xCrxO3 films prepared via the sol-gel method is crucial. Here, by adjusting the Cr content, BiFe1-xCrxO3 films with smooth surfaces and uniform grain structures were successfully synthesized. X-ray photoelectron spectroscopy (XPS) analyses revealed that Cr doping significantly reduces the concentrations of Fe2+ and oxygen vacancies within the BFO films, thereby mitigating leakage currents and enhancing ferroelectricity. Additionally, we investigated the microstructure and electrical characteristics of BiFe0.98Cr0.02O3 thin films subjected to post-annealing in different atmospheres (N2, Air, and O2). Notably, annealing in an O2 atmosphere notably enhanced the crystallinity and grain uniformity of BiFe0.98Cr0.02O3 thin films. This treatment resulted in superior ferroelectric polarization switching behavior, achieving the highest remanent polarization (Pr = 153.1 mu C/cm2) due to reduced defect densities. Our findings underscore the critical roles of Cr3+ ions and O2 annealing atmospheres in suppressing leakage currents and boosting ferroelectric properties in BFO films.