Intraband carrier relaxation in quantum dots mediated by surface plasmon-phonon excitations

A new mechanism of the intraband carrier relaxation in quantum dots embedded into a heterostructure at a relatively large distance from its doped elements is proposed. The relaxation process is related to the coupling between the electronic subsystem of a quantum dot and surface plasmon-phonon excitations of the doped components of the heterostructure via the electric potential produced by these excitations. It is found that, in layered heterostructures, the dispersion relations of the surface plasmon-LO-phonon modes display critical points giving rise to pronounced singularities in the relaxation rate spectra. The estimates of the relaxation rates for InAs quantum dots embedded into a GaAs heterostructure have shown high efficiency of the proposed mechanism even when the quantum dots are located at a distance of up to 100 nm from the doped regions of the heterostructure. When this distance lies in the range of a few tens of nanometers, this mechanism appears to be predominant. Possible manifestations of the relaxation mechanism under consideration in the photoluminescence spectra of quantum dots are discussed.