We investigate both dephasing and population relaxation of excitons localized in quantum dot like islands in narrow GaAs quantum wells by using stimulated photon echoes. A direct comparison of these two closely related decay processes reveals a pure dephasing contribution that dominates excitonic dephasing at elevated temperatures but does not involve exciton population relaxation. The pure dephasing contribution arises from coupling of excitonic states with a continuum of acoustic phonons and is enhanced by 3D quantum confinement. Both the magnitude and the temperature dependence of the pure dephasing rate can be described by a theoretical model that generalizes the Huang-Rhys theory of F-centers.
ASJC Scopus subject areas
- 化学 (全般)