Strain regulated interlayer coupling in WSe2/WS2 heterobilayer

Abstract

Strain engineering can effectively modify the materials lattice parameters at atomic scale, hence it has become an efficient method for tuning the physical properties of two-dimensional (2D) materials. The study of the strain regulated interlayer coupling is deserved for different kinds of heterostructures. Here, we systematically studied the strain engineering of WSe2/WS2 heterostructures as well as their constituent monolayers. The measured Raman and photoluminescence spectra demonstrate that the strain can evidently modulate the phonon energy and exciton emission of monolayer WSe2 and WS2 as well as the WSe2/WS2 heterostructures. The tensile strain can tune the electronic band structure of WSe2/WS2 heterostructure, as well as enhance the interlayer coupling. It is further revealed that the photoluminescence intensity ratio of WS2 to WSe2 in our WSe2/WS2 heterobilayer increases monotonically with tensile strain. These findings can broaden the understanding and practical application of strain engineering in 2D materials with nanometer-scale resolution.