Localization and homogeneous dephasing relaxation of quasi-two-dimensional excitons in quantum-well heterostructures

The mechanisms of dephasing relaxation (homogeneous linewidth) of quasi-two-dimensional excitons in quantum-well heterostructures are clarified for both localized and delocalized excitons. The recently observed energy and temperature dependences of the homogeneous linewidth ${\Gamma }_h$ are explained quantitatively. Furthermore, a new exponent for the temperature dependence of ${\Gamma }_h$ of the localized excitons at low temperatures, the energy dependence of ${\Gamma }_h$ of the delocalized excitons, and the dependence of ${\Gamma }_h$ on the quantum-well thickness are predicted.