Shear strain tunable exciton dynamics in two-dimensional semiconductors

Abstract

Inhomogeneous strain effects on exciton dynamics have become particularly attractive with the emergence of two-dimensional flexible semiconductors. However, a solid understanding of the shear strain effect is lacking. Here, we study tunable exciton dynamics in two-dimensional semiconductors that have inhomogeneous shear strain. The state-of-the-art first-principles calculations based on the GW plus Bethe-Salpeter equation formalism show that in monolayer molybdenum disulfide, an isotropic semiconductor, the exciton excitation energy can be dramatically tuned as an even function of shear strain with a deformation potential of $\ensuremath{-}50$ meV/1%, despite the induced anisotropy of optical absorption with respect to the polarization direction of incident light. For an anisotropic semiconductor such as phosphorene, the modulation of exciton excitation energy is found to be shear-direction dependent. The finite-element simulations further reveal a shear-induced funnel effect of excitons in a micrometer scale ${\mathrm{MoS}}_{2}$ disk. The enhanced understanding of inhomogeneous strain engineering presented in this study has the potential to be instrumental in the design of novel optoelectronic devices.