Influence of the InAs coverage on the phonon-assisted recombination in InAs/GaAs quantum dots

In this work, a study of the relaxation mechanisms in InAs self-assembled quantum dots have been performed by means of photoluminescence (PL), resonant PL (RPL) and PL excitation. The observed phenomenology is different for samples with different InAs coverage. At low InAs coverages, two resonant Raman scattering lines are observed when the excitation energy is chosen inside the emission band. These lines are related to the TO and LO GaAs phonons. Multi-phonon relaxation of carriers (GaAs phonons) is clearly observed in RPL and excitation PL in the lowest InAs coverage sample. Neither such mechanism nor resonant Raman scattering is present in samples with larger InAs coverages, for which the average quantum dot size and areal density remain essentially constant.