Tunable photoresponse with small drain voltage in few-layer graphene–WSe2 heterostructures

• Two contact interfaces in the graphene–WSe2 heterostructure are investigated.
• The photoresponse of two contact interfaces behaves differently.
• The properties of contact interfaces are tuned by small drain voltage.

Two-dimensional layered heterostructures show great potential to develop optoelectronic systems. Here, we have investigated the photoresponse properties of two contact interfaces in few-layer graphene–WSe2 heterostructures. The photoresponsivity of graphene–WSe2 contact interface is about 2.67 mA/W, and the photoresponsivity of WSe2–metal contact interface is about 0.2 mA/W. Photocurrent images show that the two contact interfaces behave differently under drain voltage from −0.5 V−0.5 V to 0.5 V. The photoresponsivity of one contact interface increases with the drain voltage, and that of the other decreases with the drain voltage. Experimental results and band diagram studies prove that the photoresponse properties of contact interfaces are tuned by small drain voltage. This study will be beneficial for understanding the effect of drain voltage on the heterostructures.