Broadband high-performance vertical WS_1.08Se_0.92/Si heterojunction photodetector with MXene electrode

Vertical semiconductor van der Waals heterojunctions are essential for fabricating high-performance photodetectors. However, the range of the spectral response and defect states of semiconductor materials are two critical factors affecting the performance of photodetectors. In this work, the spectral response range of WS₂was changed through WS₂band gap regulation, and a self-powered vertical WS_1.08Se_0.92/Si heterojunction photodetector with MXene electrode was prepared by synthesizing WS_1.08Se_0.92film on Si substrate and vertically stacking Ti₃C₂T_xMXene on the film. Due to the electron collection of MXene and the wonderful junction quality of WS_1.08Se_0.92/Si, the photodetector can detect near-infrared light in the range of 980-1310 nm, which exceed the detection limit of WS_1.08Se_0.92. And the device had high sensitivity in the broadband. The responsivity was 4.58 A W^-1, the specific detectivity was 4.58 × 10¹¹Jones, the on/off ratio was 4.95 × 10³, and the fast response time was 9.81/9.03μs. These properties are superior to previously reported WS₂-based photodetectors. Vertical structure, Energy band tuning, and MXene electrode provide a new idea for preparing broadband high-performance and self-powered photodetector.