Self-powered photodetection covering UV–visible regime realized in BiSb alloy/silicon heterostructure

This study successfully fabricated a quasi-single-oriented bismuth–antimony (BiSb) (0112) alloy via a dual-target magnetron sputtering method and formed a heterojunction with silicon to construct a self-powered photodetector. Experimental results indicate that the device exhibits a significant on/off ratio under both 365 and 632 nm illumination. In particular, under zero-bias conditions at 632 nm, it achieves a photoresponsivity of 0.163 A/W, a time constant of 0.8 ms, and a detectivity (D*) of 2.4 × 1010 Jones. Based on the energy band structure and carrier transport mechanism, the vital role of topological surface states in low-Sb BiSb alloys in photogenerated carrier separation is revealed, and the positive impact of high film quality on device performance is confirmed. The novelty of this work lies in the first realization of a dual-target magnetron-sputtered BiSb/Si heterojunction self-powered photodetector, clearly elucidating the optoelectronic mechanism of tunable BiSb alloys with topological or semi-metallic characteristics. This research not only broadens the application prospect of BiSb topological alloys in optoelectronic devices but also offers a feasible strategy for high-efficiency, low-power photodetectors toward 6G communication.