Bias-dependent photoresponse of T d -WTe 2 grown by Chemical Vapor Deposition.

The type-II Weyl semimetal T d -WTe 2 is one of the wonder materials for high-performance optoelectronic devices. We report the self-powered T d -WTe 2 photodetectors and their bias-dependent photoresponse in the visible region (405 nm, 520 nm, 638 nm) driven by the bulk photovoltaic effect (BPE). The device shows the responsivity of 15.8 mAW -1 and detectivity of 5.2×10 9 Jones at 520 nm. Besides, the response time of the WTe 2 photodetector shows a strong bias-voltage dependent property. This work offers a physical reference for understanding the photoresponse process of T d -WTe 2 photodetectors.