Band structure engineering of monolayer MoS₂ on h-BN: first-principles calculations

We have carried out first-principles calculations and theoretical analysis to explore the structural and electronic properties of MoS₂/n-h-BN heterostructures consisting of monolayer MoS₂ on top of h-BN substrates with one to five layers. We find that the MoS₂/n-h-BN heterostructures show indirect bandgap features with both of CBM (in the K point) and VBM (in the Γ point) localized on the monolayer MoS₂. Difference charge density and surface bands indicate there is no obvious charge exchange in the heterostructure systems. We show that the changes from a direct bandgap in monolayer free-stranding MoS₂ to an indirect bandgap in MoS₂/n-h-BN heterostructure is induced by the strain. Moreover, we find that the bandgaps of MoS₂/n-h-BN heterostructures decrease with increasing number of h-BN layers, which is proposed to result from the different strain distributions in MoS₂ due to the varieties of lattice mismatch rates between MoS₂ and h-BN layers. Our results suggest that the MoS₂/n-h-BN heterostructure could serve as a prototypical example for band structure engineering of 2D crystals with atomic layer precision. (paper)