Unveiling interface interaction assisted broadband photoresponse of epitaxial 2D Bi2O2Se on perovskite oxides

Abstract

Bi₂O₂Se has established itself as a revolutionary two-dimensional (2D) semiconductor owing to its superior electric, optoelectric and thermoelectric properties. The structural compatibility between Bi₂O₂Se and perovskite oxides makes the investigation of their heterointerfaces an intriguing frontier. Herein, we unveil the Bi₂O₂Se/SrTiO₃ interfacial interaction by studying the photoresponse of the oxide heteroepitaxy. The record-broad photosensitivity (365–1850 nm) is ascribed to a complex interplay between photoconductive, photogating, pyroelectric and photo-thermoelectric (PTE) effects. The distinctive pyroelectricity, which results in a 900-fold decrease in the response time, originates from the surface polarization and relaxation at the Bi₂O₂Se/SrTiO₃ interface. Self-powered behavior is reported for the first time in Bi₂O₂Se-based photodetectors. Under zero bias, the PTE-dominated photoresponse gives rise to a tunable polarity and magnitude of the photocurrent, and an estimated Seebeck coefficient of −127.8 μV K⁻¹. The optimal photoresponsivity of 12.62 A W⁻¹, external quantum efficiency of 1424.08% and detectivity of 1.51 × 10⁹ Jones indicate the performance advancement of the photodiodes based on as-grown Bi₂O₂Se. Our study sheds light on the exploitation of exotic physical phenomena at the heterointerfaces between Bi₂O₂Se and perovskite oxides, and also indicates that 2D Bi₂O₂Se has a wide range of applications in piezoelectrics, ferroelectrics, self-powered nanogenerators and optical communications.