Doping-induced non-Markovian interference causes excitonic linewidth broadening in monolayer WSe2

Strong Coulomb interactions in atomically thin semiconductors like monolayer WSe(2)( )induce not only tightly bound excitons, but also make their optical properties very sensible to doping. By utilizing a microscopic theory based on the excitonic Heisenberg equations of motion, we systematically determine the influence of doping on the excitonic linewidth, line shift, and oscillator strength. We calculate trion resonances and demonstrate that the Coulomb coupling of excitons to the trionic continuum generates a non-Markovian interference, which, due to a time retardation, builds up a phase responsible for asymmetric exciton line shapes and increased excitonic linewidths. Our calculated doping dependence of exciton and trion linewidths, line shifts, and oscillator strengths explains recent experiments. The gained insights provide the microscopic origin of the optical fingerprint of doped atomically thin semiconductors.

Automated summary

In this study, the influence of doping on the excitonic properties of atomically thin semiconductors was systematically investigated using a microscopic theory based on the excitonic Heisenberg equations of motion. The calculated results reveal the effects of Coulomb coupling between excitons and the trionic continuum on the exciton line shape and linewidth, explaining recent experimental observations. These insights provide a microscopic understanding of the optical properties of doped atomically thin semiconductors.