Unveiling the link between preparation conditions and ferroelectric properties in spin coated bismuth ferrite thin films

In solution–based deposition of bismuth ferrite, the annealing temperature and environment affect the film properties. The requirement for annealing above 500 °C makes it incompatible with complementary metal oxide semiconductor (CMOS) technology; however, it can be used as a standalone memory device. This study investigates various annealing temperatures and durations for changes in structural, morphological, compositional, and ferroelectric properties. A balance between the annealing conditions and oxygen vacancies is essential for device applications. Minor changes in the XRD patterns were observed owing to changes in the annealing conditions. Changes include pores as indicated by morphological studies, a drop in bandgap, loss of resistive switching, variation in polarisation, and resistive leakage in the P–E hysteresis loop. PUND measurements show the maximum polarisation of 3.96 µC/cm². First-principles calculations of electronic properties found that oxygen vacancies contribute to increased hybridisation between Fe and O, and aid in magnetisation and conduction. Oxygen vacancies cause distinct changes in the electronic properties of bismuth ferrite. Through experimental and computational means, it is shown that large variations in functional properties such as I–V characteristics, leakage current, and ferroelectric properties occur with minor changes in the deposition parameters.