Self‐Powered and Vis‐Infrared Broadband Gr/InSe/MoTe₂ Heterostructure Photodetectors with Ultra‐Fast Response and Low Dark Current

Abstract Self‐powered photodetection devices, which meet the requirement of environmental sustainability, are widely designed by PN heterojunctions. The design of the semiconductor/metal interface is vital in PN‐junction devices. In particular, the elevated potential barrier at the metal/semiconductor interface impedes efficient carrier transport. Therefore, optimizing the semiconductor/metal interface for the PN junction, either by reducing the interface barrier or leveraging the built‐in electric field within the Schottky junction, holds significant importance in enhancing the performance of PN‐junction devices. In this study, an InSe/MoTe 2 Type‐II PN heterojunction photodetector is constructed, with graphene (Gr) and gold (Au) serving as electrodes in contact with InSe and MoTe 2 , respectively. Benefiting from the reduced barrier in Au/InSe interfaces and the built‐in electric field formed at the InSe/MoTe 2 and MoTe 2 /Au interfaces in the same direction, the device achieves an ultra‐fast photoresponse speed of 14 µs and an ultra‐low dark current of 8.5 × 10⁻¹⁴ A at zero bias. Furthermore, the device exhibits a remarkable light on/off ratio up to 10 5 and achieves broad‐spectrum photodetection ranging from the visible to infrared wavelength. This research highlights the enormous potential of the Gr/InSe/MoTe 2 van der Waals heterostructure in the realms of self‐powered photodetection, imaging, and optical communication.