Lattice defect assisted incorporation of Mn²⁺ ions in cubic II-VI semiconductor quantum dots

Electron paramagnetic resonance spectra from substitutional Mn²⁺ ions in quantum dots of cubic ZnS with tight size distribution centred at 2 nm were recorded in the 9.8 GHz and 34 GHz frequency bands. Their quantitative analysis with line shape simulation and fitting computer programs accounting for both forbidden transitions and line broadening effects demonstrate the presence of a local axial distortion attributed to a neighbouring extended planar stacking defect. The presence of such extended lattice defects, confirmed from a high resolution transmission electron microscopy study on presently investigated cubic ZnS quantum dots, seems to be essential in the incorporation and localization of Mn²⁺ activating ions in other cubic II-VI semiconductor quantum dots as well.