Exciton Spectroscopy of Single CdTe and CdMnTe Quantum Dots

Abstract

Single dot optical spectroscopy results obtained for CdTe and CdMnTe self-assembled quantum dots in ZnTe matrix are reported. In order to resolve the emission from individual dots apertures with diameter below 200 nm were opened in a metal masks. In the case of CdTe dots, sharp emission lines with a linewidth below 200 μeV were observed. From a magnetic field dependence of the emission energy the exciton effective g-factor is deduced to be equal to —3 and it is found to be independent of the energy of the quantum dot emission at B = 0 T. On the other hand, for CdMnTe quantum dots, broad (∼3–5 meV) emission lines related to a single dot emission were observed. Moreover, the Zeeman splitting of these lines is found to be comparable with their linewidth. The observed behavior is attributed to either high manganese concentration in the dots or to confinement induced decrease of exchange constants in magnetic quantum structures.