The effect of strain on the electronic properties of MoS2 monolayers

We utilize first-principles calculations within density-functional theory to investigate the possibility of strain engineering in the tuning of the band structure of two-dimensional MoS2. We find that the band structure of MoS2 monolayers transits from direct to indirect when mechanical strain is applied. In addition, we discuss the change in the band gap energy and the critical stains for the direct-to-indirect transition under various strains such as uniaxial, biaxial, and pure shear. Biaxial strain causes a larger change, and the pure shear stain causes a small change in the electronic band structure of the MoS2 monolayer. We observe that the change in the interaction between molecular orbitals due to the mechanical strain alters the band gap type and energy.