Highly sensitive and broadband photodetectors based on WSe₂/MoS₂heterostructures with van der Waals contact electrodes

A nanoscale photodetector is a crucial part of intelligent imaging and wireless communication devices. Building van der Waals (vdWs) heterostructures based on two-dimensional transition metal dichalcogenides is thought to be a smart approach for achieving nanoscale photodetectors. However, the pinning effect induced by surface states, defects, and metal-induced gap states during the fabrication process of vdWs heterostructures and contacting electrodes leads to a large Schottky barrier and consequently limits the photoresponse of vdWs heterostructures. In this study, a photodetector based on the WSe2/MoS2 heterostructure with graphene (Gr)/indium tin oxide (ITO) hybrid electrodes has been fabricated. The vdWs contacts established between the exfoliated graphene layers and WSe2/MoS2 heterostructure are able to get rid of lattice damages caused by atom bombardment during the deposition of metal electrodes. In addition, the reduced Schottky barrier at graphene/heterostructure interfaces facilitates the transport of carriers. Experimental results show that the photodetector based on WSe2/MoS2 heterostructures with Gr/ITO hybrid electrodes exhibits a high responsivity of up to 1236.5 A W-1, a detectivity of up to 1.23 × 1013 Jones, and a fast response of 270/130 μs to light from the ultraviolet to near-infrared range.