Optical- and acoustical-phonon-assisted hopping of localized excitons in CdTe/ZnTe quantum wells

Interaction with both acoustical as well as optical phonons contributes to the relaxation of excitons in tail states of coherently strained CdTe/ZnTe quantum wells. The contribution of acoustical phonons is most important in the thinnest well of 1.8 monolayers. Hopping down, which involves the emission of acoustic phonons, leads to a redshift of the luminescence band of about 10 meV within the first 200 ps after excitation. A comparison of the experimental data with results of a quantitative theory allows us to evaluate the concentration of localized states involved in the relaxation process.