Ferroelectric properties of Au/Bi3.25La0.75Ti3O12/ITO thin film capacitors deposited under different partial oxygen pressures

Bi3.25La0.75Ti3O12 thin films were deposited onto indium-tin-oxide (ITO) coated glass substrates by the pulsed laser ablation method at a deposition temperature of 400 °C and an annealing temperature of 650 °C. An attempt to control the oxygen-induced defects in the ferroelectric material was conducted by varying the conditions of the deposition pressures. The fatigue properties resulted in a constant polarization switching due to charged oxygen vacancies for oxygen deficient 50 mTorr prepared films, and decreasing polarization with co-existing ferroelectric and pyrochlore phase for excessive oxygen 500 mTorr prepared films. However, for the film prepared at 200 mTorr, an unusual increase in the polarization value was observed. This might be attributed to the formation of a p–n junction with the n-type electrode and p-type ferroelectric material that creates a built-in bias inside the ferroelectric film or near the interface, concentrating the polarity to the direction of the electrode.