Photoluminescence structure of highly excited quantum dots of type II

The photoluminescence (PL) due to decay of exciton-like e-e-h complex X- (expected to appear for higher levels of activation) in electrically defined quantum dots of type II is analyzed within the Hartree approach for Gaussian confining potential, where the existence of metastable (against far-infrared interband dipole transitions) states is predicted, due to interplay of bare confinement with Coulomb interaction between the carriers. As we will show, when three-particle complexes (e-e-h) are taken into account, three PL peaks can occur at zero magnetic field, which further split into four peaks when external magnetic field is applied, which stands in a good correspondence with the experimental observations. The QD size and external magnetic field dependencies of the PL spectrum are analyzed, also finding good experimental confirmation.