High‐Performance, Self‐Driven Photodetector Based on Graphene Sandwiched GaSe/WS₂ Heterojunction

Restacking the exfoliated 2D layered materials into complex heterostructures with new functionality has opened a new platform for materials engineering and device application. In this work, graphene sandwiched p‐GaSe/n‐WS 2 vertical heterostructures are fabricated for photodetection. The devices show excellent performance on photodetection from ultraviolet to visible wavelength range, including high photoresponsivity (≈149 A W −1 at 410 nm), short response time of 37 µs, and self‐powered photodetection. The scanning photocurrent microscopy is also employed to investigate the photocurrent generation in the heterojunction and a significant enhancement of the photoresponse is found in the overlapping region. The results suggest that the graphene sandwiched vertical heterojunctions are promising in future novel optoelectronic devices applications.