Stimulated emission of terahertz acoustic phonons as a result of action of nonequilibrium phonons upon the localized exciton ensemble

The influence of nonequilibrium phonons created by an external source on the relaxation and lateral migration of excitons in an ultrathin CdTe/ZnTe quantum well was studied. It was found that under action of nonequilibrium phonons upon the localized exciton ensemble the transitions between localized states occur; these transitions are assumed to be accompanied by stimulated terahertz–phonon emission. The surprising fact is that the phonon effect reveals already for a low power of phonon generation. This indicates that a rather intense exciton relaxation in energy under the nonequilibrium phonon action occurs within the range of localized states.