Annealing effect on photoluminescence of two dimensional WSe2/BN heterostructure

Controlling or eliminating the extrinsic interfacial effects is an important concern in the studies of two-dimensional van der Waals (2D vdW) heterostructures. In this Letter, by using WSe2/BN as a model, the annealing effect on the elimination of extrinsic interfacial effects in 2D vdW heterostructures was studied. The formation of the WSe2/BN interface can generate interfacial defects and significantly regulate the type and peak intensity percentage of WSe2 photoluminescence (PL) peak. It is intriguing to find that the thermal annealing effect on the optical property is opposite to that from extrinsic defects. By optimizing the annealing temperature, the PL of the functional-layer WSe2 in the heterostructure is gradually restored. This finding demonstrates that the thermal annealing can efficiently minimize the extrinsic interfacial effects, which may provide a simple and low-cost route to fabricate high-quality 2D vdW devices.