Determination of the number of Mn ions inside CdMnTe self assembled quantum dots

Abstract

We have grown self assembled CdMnTe/CdZnTe quantum dots with small amount of Mn ions by molecular beam epitaxy. Using atomic layer epitaxy growth mode for the deposition of the QDs layer, we were able to add the manganese ions only into the two central monolayers of six monolayers-thick CdTe layers, thus, achieving great dilution of Mn ions. Micro-photoluminescence measurements performed in an external magnetic field confirmed that the Mn ions are successfully incorporated in the CdTe QDs, which manifests itself by the strong circular polarization and the giant Zeeman splitting of PL-lines coming from individual QDs. Studying the magnetic field dependencies of several QDs from our ensemble, we found that the energy shifts acquire, approximately, only few nearly discrete values. We attribute this effect to small number of Mn ions inside our QDs that contribute to the splitting of excitons and we use the saturation values of the shift it to determine this number precisely.