Atomic-Scale Interface\nModification in Complex Oxide\nHeterojunctions for Near-Infrared Photodetection

Photodetectors that detect near-infrared (NIR) light\nserve as important\ncomponents in contemporary energy-efficient optoelectronic devices.\nHowever, detecting the low-energy photons of the NIR light has long\nbeen challenging since the ease of photoexcitation inevitably involves\nincreasing the background current in the dark. Herein, we report the\natomic-scale interface modification in SrRuO<sub>3</sub>/LaAlO<sub>3</sub>/Nb-doped SrTiO<sub>3</sub> (SRO/LAO/Nb:STO) heterostructures\nfor NIR photodetection. The interfacial band alignment by a polar\nmonolayer LAO allows precise tuning of the Schottky barrier to achieve\na specific energy band profile suitable for the NIR photodetection.\nThe SRO/LAO/Nb:STO heterojunctions show a high photoresponsivity up\nto ∼1.1 mA/W under NIR light irradiation (λ = 850 nm),\nwhile keeping the pA-scale dark current. The increase in the responsivity\nby interface modification is evaluated at a maximum of 1371%. Based\non the enhanced NIR photoresponsivity, as a proof of concept, we demonstrate\nthe spatial imaging of NIR signals using a conceptual array of SRO/LAO/Nb:STO\nheterojunctions. In addition, the experimental-data-based simulation\nverifies that the array device can implement pulse-number-dependent\nplasticity, which is based on the characteristic persistent photoconductivity.\nThis study suggests that atomic-scale interface modification is a\nfacile and powerful method for optimizing the photoresponsive properties\nof complex-oxide-based heterojunctions.