Piezoelectricity enhancement and bandstructure modification of atomic defect-mediated MoS2 monolayer.

Abstract

Piezoelectricity appears in the inversion asymmetric crystal that converts mechanical deformation to electricity. Two-dimensional transition metal dichalcolgenide (TMDC) monolayers exhibit the piezoelectric effect due to inversion asymmetry. The intrinsic piezoelectric coefficient (e11) of MoS2 is ∼298 pC m-1. For the single atomic shift of Mo of 20% along the armchair direction, the piezoelectric coefficient (e11) of MoS2 with 5 × 5 unit cells was enhanced up to 18%, and significantly modified the band structure. The single atomic shift in the MoS2 monolayer also induced new energy levels inside the forbidden bandgap. The defect-induced energy levels for a Mo atom shift along the armchair direction are relatively deeper than that for a S atom shift along the same direction. This indicates that the piezoelectricity and band structure of MoS2 can be engineered by a single atomic shift in the monolayer with multi unit cells for piezo- and opto-electric applications.