Graphene‐Embedded MoS 2 /WSe 2 van der Waals Heterojunction for Gate‐Tunable High‐Performance Photodetectors

ABSTRACT Photodetectors featuring high responsivity, detectivity, and broadband response are crucial for applications in optical communications, imaging, and sensing. Nevertheless, most reported devices based on conventional van der Waals (vdW) heterojunctions are often limited by interfacial defects and material properties, making it difficult to simultaneously achieve fast response, high sensitivity, and wide spectral detection. To overcome this challenge, we design and fabricate a gate‐tunable MoS 2 /Graphene/WSe 2 vdW heterojunction photodetector. In this configuration, the n‐type MoS 2 and p‐type WSe 2 form a type‐II vdW P‐N heterojunction that effectively suppresses dark current and promotes efficient carrier separation, while the graphene interlayer not only passivates interfacial defects and facilitates efficient carrier transport but also extends the photoresponse range. Under 520 nm illumination with a gate voltage of 20 V and a bias of 1 V, this device achieves a responsivity of 7.8 × 10 3 A/W, a detectivity of 8.7 × 10 1 3 Jones, an external quantum efficiency of 2.4 × 10 6 %, and a broad spectral response spanning from 405 to 1064 nm. Additionally, an ultrafast response time of 20 µs is obtained, and the pronounced gate‐tunable behavior is also observed. Moreover, its potential for applications in high‐speed transmission and imaging is demonstrated. These results suggest that the proposed vdW heterojunction engineering strategy offers a promising pathway toward high‐performance optoelectronic devices.