Room-temperature giant persistent photoconductivity in SrTiO ₃/LaAlO ₃ heterostructures

SrTiO ₃/LaAlO ₃ interfaces show an unprecedented photoconductivity effect that is persistent even at room temperature and giant as it gives rise to a conductivity increase of about 5 orders of magnitude at room temperature. The persistent photoconductivity effects play a paramount role in the still controversial intrinsic behavior of the SrTiO ₃/ LaAlO ₃ interfaces, as even a limited exposure to visible light is able to strongly modify the electrical transport properties of the interface even above room temperature, while only an appropriate thermal treatment in a dark environment can completely suppress the persistent photoconductivity effect unveiling the intrinsic conduction mechanism of the interface. Moreover, our study demonstrates that the origin of the high conductivity, revealed at the STO/LAO interface at room temperature, is purely electronic.