Exciton-phonon interactions and exciton dephasing in semiconductor quantum-well heterostructures

We have investigated exciton-phonon coupling and related exciton dephasing processes in monolayer semiconductor heterostructures with localized quasi two-dimensional (2D) excitonic states. The calculated lateral size dependence of low-temperature Huang-Rhys factors indicates the enhancement of exciton-phonon coupling with decreasing the lateral size of the quasi-2D exciton localization area. This entails the increase of exciton dephasing. At low temperatures, the exciton absorption line exhibits an essentially non-Lorentzian asymmetric shape with the asymmetry increasing with the decrease of temperature and the lateral size of the quasi-2D exciton localization area.