Metal‐Semiconductor Phase Transition in Multilayer VSe₂ for Broadband Photodetector with High Sensitivity

Abstract 2D 1T‐VSe 2 is a charge‐density wave (CDW) system that also exhibits room‐temperature ferromagnetism, making it promising for photodetecting devices. However, the sensitivity of 1T‐VSe 2 photodetectors is limited by the high dark current due to its metallic feature of T‐phase VSe 2 . So far, photodetectors based on semiconducting 2H‐phase VSe 2 have ever been reported. In this work, the metal‐semiconductor phase transition (1T to 2H) in multilayer VSe 2 by thermal annealing process, and the fabrication of 2H‐VSe 2 broadband photodetectors with high sensitivity is reported. The 2H‐VSe 2 photodetectors exhibit low dark current and a broad spectral range of 405–1550 nm. The responsivity (R) and detectivity (D*) can reach up to 75.26 A W −1 and 1.45 × 10 10 Jones at V sd of 1 V, outperforming photodetectors based on 1T‐VSe 2 and other 2D materials for the 1550 nm optical communication band. This work showcases a facile method for obtaining the metal‐semiconductor phase transition of VSe 2 and demonstrates the potential of 2H‐VSe 2 for high‐performance near‐infrared photodetectors.