Thickness dependence of photoresponsive properties at SrTiO₃-based oxide heterointerfaces under different strains

The photoresponsive characteristics of SrTiO₃-based oxide heterointerfaces at different thicknesses and strains are investigated. In addition to the typical persistent photoconductivity, the transient photoconductivity is observed at the heterointerfaces below the critical thickness. More intriguingly, it shows a transition from the transient photoconductivity to the persistent photoconductivity for the interfaces at the critical thickness with enhancing temperatures, which is related to the dominant role of thermal energy. Moreover, larger strain at the LaAlO₃/SrTiO₃ interfaces produces a roughly greater photoinduced change in the resistance than the strain-relaxed (La_0.3Sr_0.7)(Al_0.65Ta_0.35)O₃/SrTiO₃ interfaces. Our results provide deeper insight into the photoresponsive properties and intrinsic mechanisms of two-dimensional electron gas at complex oxide interfaces.