Growth and characterization of CdSe:Mn quantum dots

In this paper we report the growth by atomic layer epitaxy (ALE) and optical properties of ZnSe/CdSe:Mn magnetic quantum dots. For samples grown without a ZnSe capping layer, dot densities of the order of 10⁹cm^-2 were measured by atomic force microscopy (AFM). In capped samples, the ensemble dot photoluminescence (PL) was observed over a range of energies between 2.1 and 2.5 eV and a spectrally broad emission at 2.15 eV from the internal Mn²⁺ transition was observed at high Mn concentrations. Single dot spectroscopy was carried out by confocal microscopy and the PL linewidth was measured as a function of Mn concentration. At high Mn concentrations the temporal change in magnetization causes a broadening of the FWHM of lines from single dots of up to 4 meV. However, for low concentrations single dot PL linewidths were resolution limited at <0.2 meV.