Ambipolar Photoresponsivity in an Ultrasensitive Photodetector Based on a WSe₂/InSe Heterostructure by a Photogating Effect

Ambipolar photoresponsivity mainly originates from intrinsic or interfacial defects. However, these defects are difficult to control and will prolong the response speed of the photodetector. Here, we demonstrate tunable ambipolar photoresponsivity in a photodetector built from vertical p-WSe₂/n-InSe heterostructures with photogating effect, exhibiting ultrahigh photoresponsivity from −1.76 × 10⁴ to 5.48 × 10⁴ A/W. Moreover, the photodetector possesses broadband photodetection (365–965 nm), an ultrahigh specific detectivity (D*) of 5.8 × 10¹³ Jones, an external quantum efficiency of 1.86 × 10⁷%, and a rapid response time of 20.8 ms. The WSe₂/InSe vertical architecture has promising potential in developing high-performance nano-optoelectronics.