The study of open circuit voltage in Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterojunction structure

Bi0.9La0.1FeO3 thin films have been grown on La0.7Sr0.3MnO3/SrTiO3 substrates by using pulsed laser deposition with Ag as the top electrode. The intrinsic open circuit voltage (Voc) (without light illumination) as large as 5.8 V was observed in this hetero-junction structure. Influences of electric pulse treatment, light illumination and measurement duration time on the Voc were studied, significant Voc improvements were observed after shortening the measuring duration time and/or consistent negative pulses, yet Voc dropped obviously with consistent positive pulses and/or with light intensity increasing. Two stable states with high and low Voc can be switched with optical switching, this may be useful in practical application. Accumulation of oxygen vacancies with positive charges near the interface is proposed to explain these results.