Polaron Interaction in InAs/GaAs Quantum Dots and Resonant Photoluminescence

In an adiabatic approach, the efficiency of the electron–phonon interaction (EPI) can be determined by measuring the ratio between the intensities of two of the phonon replicas that EPI induces in photoluminescence (PL) spectra. In low-dimensional structures such as InAs/GaAs quantum dots (QDs), this ratio depends on the excitation energy Eexc. Moreover, the evolution of the PL spectra intensity and lineshape with Eexc is quite elaborate. We reproduce well this evolution forEexc ranging from far below to above the GaAs bandgap by introducing an effective Huang-Rhys factor S, a commonly used measure of EPI. Nevertheless, the value of S remains much higher than predicted in an adiabatic model, which can hardly account for the reported dependence of S on QD size and shape. The likely source of this lack of consistency is briefly discussed.