Homogeneous linewidth broadening and exciton dephasing mechanism in MoT e2

Spectroscopic studies of mechanically exfoliated monolayer MoTe2 were performed over a wide temperature range from 4.2 to 300 K. At a low temperature, the photoluminescence spectra for monolayer MoTe2 showed two sharp peaks for excitons and charged excitons (trions). The homogeneous linewidth of the exciton peak broadened linearly as the temperature increased. This linear linewidth broadening was caused by acoustic-phonon scattering of the exciton, i.e., shortening of exciton dephasing. The broadening factor due to exciton-acoustic-phonon interactions was found to be 0.11meVK-1. This small value for the exciton-phonon coupling coefficient and the lack of a Stokes shift suggest that exciton-phonon interactions in monolayer MoTe2 are in the weak coupling regime.