Nanosize induced effects in luminescent ZnS:Mn2+ quantum dots

• Cubic ZnS:Mn2+ quantum dots were investigated by EPR, XRD and HRTEM.
• Localization of Mn2+ ions next to stacking defects influences the optical properties.
• Surface layers of different composition can influence the structural properties.

Nanocrystals (NCs) of II–VI semiconductors of few nanometers average size, called quantum dots (QDs), are now intensely investigated as radiation detectors. Besides the expected quantum confinement and influence of surface states, our electron paramagnetic resonance investigations of cZnS QDs doped with Mn2+ ions, correlated with structural data, underline that other properties should be also taken into consideration in developing the II–VI semiconductor QDs as radiation detectors. Thus, the preferential localization of Mn2+ in the core of the cubic ZnS QDs at substitutional Zn2+ cation sites next to a stacking lattice defect is expected to lead, besides changes in the impurity energy levels, to specific aggregation properties. An outer shell of different composition can also influence the structural properties of the QDs core with effects on the optical properties as well.