Optical properties of excitons in two-dimensional transition metal dichalcogenide nanobubbles.

Abstract

Strain in two-dimensional transition metal dichalcogenide has led to localized states with exciting optical properties, in particular, in view of designing one photon sources. The naturally formed nanobubbles when the MoS2 monolayer is deposited on an hBN substrate lead to a local reduction in the band gap due to strain developing in the nanobubble. The photogenerated particles are thus confined in the strain-induced potential. Using numerical diagonalization, we simulate the spectra of the confined exciton states, their oscillator strengths, and their radiative lifetimes. We show that a single state of the confined exciton is optically active, which suggests that the MoS2/hBN nanobubbles are a good candidate for the realization of single-photon sources. Furthermore, our calculations show that the localized exciton gains in activation energy and radiative lifetime inside the nanobubble, the latter decreasing toward the one of free excitons when the nanobubble size increases.