Enhanced Self‐Powered Photoresponse of a Bi₂Te₃‐Based Vertical Heterojunction Broadband Photodetector by Carrier Blocking Layer Engineering

Self-powered broadband photodetectors (SPBDs) have received widespread attention due to their significant applications in optical communication, remote sensing, and imaging. Vertical heterojunctions are promising for SPBDs due to their efficient photogenerated carrier separation and high integration density. However, certain band alignments at the interface can drive carriers to recombine that undermines the former advantage. Here, a SPBD based on the Bi₂Te₃/Sb₂O₃/p-Si vertical heterojunction is developed that introduces the Sb₂O₃ as a carrier blocking layer and achieves improved self-powered photoresponse than Bi₂Te₃/p-Si. A one-step electron beam evaporation approach is adopted to deposit a narrow-bandgap optical-active layer Bi₂Te₃ and a blocking layer Sb₂O₃ on p-type Si substrates. Such photodetector exhibits detection performance across a broad response band of UV-vis-NIR (254-1050 nm). Owing to the built-in electric field within the heterojunction, the blocking effect and the photovoltaic effect induced by the Sb₂O₃ layer, the detector achieves high responsivity (316.5 mA·W^-1), detectivity (6.19 × 10¹¹ Jones) and fast rise and decay times (24.6/25.1 ms). Furthermore, the device exhibits excellent imaging capabilities for UV, visible, and near-infrared light patterns. The work presents a SPBD using Bi₂Te₃-based vertical heterostructure and proposes a novel and instructive performance-enhancing approach using a metal oxide layer based on carrier blocking layer engineering.