Self-powered detection and near-infrared optical communication achieved with Bi₂Se₃/Si broadband photodetectors

As a topological insulator material, bismuth selenide (Bi₂Se₃) exhibits unique physical properties and a narrow bandgap, offering significant potential for applications in next-generation optoelectronic devices. Nevertheless, its narrow bandgap characteristic causes transient carriers generated by photoexcitation to relax rapidly, hindering the realisation of ideal photodetection performance and impeding practical applications. This study addresses this challenge by combining a simple, cost-effective synthesis method with bandgap engineering. By constructing an internal electric field at the heterojunction interface, we effectively suppress carrier recombination, facilitating rapid charge separation and collection. The resulting self-powered photodetector achieves a responsivity of 48.3 mA/W, a specific detectivity of 9.42 × 10¹¹ Jones, and a millisecond-range response time under 808 nm illumination. Furthermore, the device possesses broadband detection capability spanning the visible to infrared spectrum. Moreover, the device functions as a signal receiver for precise near-infrared optical communication at zero bias, demonstrating potential for application in the field of optical communications. In view of the simple, scalable and silicon-compatible fabrication method, the fabrication of Bi₂Se₃/Si photodetectors holds significant application potential in the fields of rapid broadband detection and optical communications, and also offers novel insights for the construction of other silicon-based detectors.