Discrepancy between photoluminescence and photoresponse intensities in n-InAs/GaAs and InAs/n-GaAs quantum-dot heterostructures

We report a discrepancy between near-infrared photoluminescence (PL) and far-infrared photoresponse (PR) efficiencies in self-assembled InAs/GaAs quantum-dot (QD) heterostructures with silicon doping in either InAs QDs or GaAs barriers. The structure with n-GaAs barriers reveals a much higher PR intensity in spite of a weaker PL intensity in comparison with n-InAs QD structure. This discrepancy is explained by differences in the electron occupation of QD sublevel associated with the Fermi-level position and in the mean free path of photogenerated carriers in GaAs barriers due to impurity scattering.