Near-Infrared Photodetection Enable by Atomic-scale Interface Modification in Complex Oxide Heterostructures

The development of high-performance near-infrared(NIR) photodetectors is important for a broad range of optoelectronic applications, such as night sensing, optical communications, and security. In this study, we report the atomic-scale interface modification in SrRuO₃/LaAlO₃/Nb-doped SrTiO₃ (SRO/LAO/Nb:STO) heterostructures for NIR photodetection. The interfacial band alignment by a polar monolayer LAO allows precise tuning of Schottky barrier to achieve a specific energy band profile suitable for the NIR photodetection. The interface-modified SRO/LAO/Nb:STO heterojunctions show a high photoresponsivity up to ~1.1 mA/W under NIR light irradiation (λ=850 nm), while keeping the pA-scale dark current. The increase in the responsivity by the interface modification is evaluated at a maximum of 1,371%. Based on the enhanced NIR photoresponsivity, as a proof of concepts, we demonstrate the spatial imaging of NIR signals using a conceptual array of the SRO/LAO/Nb:STO heterojunctions. In addition, our experimental-data-based simulation verifies that the array device can implement the pulse-number-dependent plasticity, which is based on its characteristic persistent photoconductivity. Our study suggests that the atomic-scale interface modification is a simple and effective method for enhancing the NIR photoresponsive properties of complex oxide heterostructures.