Bias-dependent photoresponse of T_d-WTe₂grown by chemical vapor deposition

The type-II Weyl semimetal T_d-WTe₂is one of the wonder materials for high-performance optoelectronic devices. We report the self-powered T_d-WTe₂photodetectors 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^-1and detectivity of 5.2 × 10⁹Jones at 520 nm. Besides, the response time of the WTe₂photodetector shows the strong bias-voltage dependent property. This work offers a physical reference for understanding the photoresponse process of T_d-WTe₂photodetectors.