Effect of biaxial [110] strain on monolayer MoS2 and its vacancy defect system: A first-principles study

In this paper, the effects of biaxial [110] strain synergistic vacancy defects on the binding energy, electronic structure, and optical properties of monolayer MoS2 were investigated using first-principles based on density functional theory. The results show that the monolayer MoS2 is the most stable in the unstressed state, when it has vacancy defects, the stability decreases slightly, and the binding energy decreases with the increase of the absolute value of the strain. Monolayer MoS2 is a semiconductor with a direct band gap of 1.73 ​eV. When Mo-vacancy appears, the band gap decreases significantly and the metallicity increases. When S-vacancy appears, the direct band gap transforms into an indirect band gap and the forbidden bandwidth decreases. The optical properties of the material are red-shifted by tensile strain, and blue-shifted by compressive strain. The strain coordinated vacancy defects have a significant effect on the regulation of the optical properties of monolayer MoS2. The synergistic strain effect of vacancy provides some theoretical support for the application of monolayer MoS2 in optics and other fields.