The two-dimensional electron gas (2DEG) at the LaAlO3/SrTiO3 (LAO/STO) interface exhibits many emergent properties, such as high mobility, giant photoconductivity, the light-enhanced gating effect, etc., which are invaluable for basic research and potential applications. In this work, we report an unusual enhancement of persistent photoconductivity (PPC) by electrostatic gating (EG) at the LAO/STO interface. Under the influence of pre-EG processing, the 2DEG at the LAO/STO interface is triggered into a resistance state showing a more pronounced optical response and greatly enhanced PPC under light illumination (LI) at room temperature. These observations are found to be attributed to EG-induced interfacial polarization and the subsequent LI-accelerated depolarization at the interface. Based on these findings, a nonvolatile memory device made by this interface is proposed. Our work offers a new perspective for tuning the photoelectrical properties at the oxide interface, which is helpful for designing advanced photoelectric devices with high performance and multifunctionality.
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