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, 520, 638 nm) driven by the bulk photovoltaic effect. 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 the strong bias-voltage dependent property. This work offers a physical reference for understanding the photoresponse process of T d -WTe 2 photodetectors.