Optical properties of annealed CdTe self-assembled quantum dots

We report on the influence of postgrowth thermal annealing on the optical properties of CdTe/ZnTe self-assembled quantum dots (SAQDs). Ultrasharp emission lines in the micro-photoluminescence spectra demonstrate the continued presence of quantum dots (QDs) after annealing. Upon annealing, the emission from CdTe QDs shifts toward higher energies with a narrowing of the photoluminescence line of QDs ensemble. In addition, the decay time of the excitonic recombination decreases from 300 ps to 200 ps. These results indicate that interdiffusion of Zn and Cd into and out of the QDs leads to an increase of the average dot size and simultaneously a decrease in the confining potentials of the QD. The absence of a wetting layer makes the II–VI CdTe SAQDs much more sensitive to the thermal treatment than the III–V InAs-based dots.