Electrical Transparency of Tungsten Disulphide-Graphene Heterostructures

Vertical heterostructures of tungsten disulphide on graphene (WS₂/graphene) are relevant for optoelectronic, spintronic, and valleytronic devices, all requiring detailed knowledge of the electronic interface properties.<br/>We investigated the electrical nature of such interfaces without conventional device integration and associated fabrication that is often detrimental to the structural integrity of monolayer materials, by using a four-probe scanning tunnelling microscope. The measurements provided important insights into the electrical transport properties of monolayer WS₂ synthesized by chemical vapour transport on epitaxial graphene, featuring a Schottky-type contact between the metallic probe and WS₂, but Ohmic transport in the WS₂/graphene heterostructure, and a highly transparent interface evidenced by the measured four-probe resistances. <br/>The electrical transparency of the WS₂/graphene interface is of considerable significance to a range of applications related to ultrathin electronics and optoelectronics seeking to overcome challenges associated with achieving optimized and reliable contacts to atomically thin materials.