Inhomogeneous saturation of excitons in monolayer transition-metal dichalcogenides
We observe that the apparent inhomogeneous broadening, as measured by two-dimensional coherent spectroscopy (2DCS), of the exciton resonance in transition-metal dichalcogenide monolayers depends on the excitation strength. A key strength of 2DCS is the ability to separate inhomogeneous broadening, which primarily contributes to the diagonal linewidth, from homogeneous broadening, which dominates the cross-diagonal linewidth. We show that the fluence dependence of the diagonal linewidth arises from the effective saturation fluence varying with the exciton's resonance energy, i.e., inhomogeneous saturation. These results are critical for interpreting the exciton linewidths, which are often used as a measure of sample quality.
cond-mat.mes-hall↗