Origin of luminescence quenching in structures containing CdSe/ZnSe quantum dots with a few Mn$^{2+}$ ions

We present a detailed spectroscopic study of the photoluminescence quenching in an epitaxial sample containing CdSe/ZnSe quantum dots (QDs) doped with low concentration of Mn$^{2+}$ ions. Our time-resolved and time-integrated experiments reveal the origin of the quenching observed in macro-photoluminescence studies of ensembles of such dots. We show that incorporation of even a few ions to an individual dot has little influence on its luminescence. At the same time, the presence of Mn$^{2+}$ ions in the sample significantly affects the luminescence intensity of the wetting layer. However, it does not affect the luminescence decay, which suggests that the observed quenching occurs for excited excitonic states.