Formation mechanism and twist-angle dependent optical properties of bilayer MoS2 grown by chemical vapor deposition

Abstract

Twisted molybdenum disulfide (MoS₂) has attracted significant scientific interest due to its unique physical properties. In this work, we report the growth of bilayer MoS₂ with a variety of twist angles by a face-to-face chemical vapor deposition (CVD) method. It has been demonstrated by molecular dynamics (MD) simulations that the formation of the twisted bilayer flakes depends on the sliding and rotation behavior of top triangular layers. The effects of the twist angle on the optical properties of twisted bilayer MoS₂ have been proved by Raman and photoluminescence (PL) analysis. Raman results show that the interlayer coupling can be tuned by the twist angle. The valence-band splitting is related to the PL A and B excitons and the A–B exciton separation, which are dependent on the twist-angles. The current work demonstrates the CVD synthesis of twisted bilayer MoS₂ and its potential in tuning the electronic and photonic properties of MoS₂.