CdSe self-assembled quantum dots grown on ZnMnSe diluted magnetic semiconductors with different Mn concentration

We have investigated magneto-optical properties of a series of CdSe self-assembled quantum dots (QDs) grown on the Zn1−xMnxSe diluted magnetic semiconductors (DMSs). The QDs are formed by depositing 2.5 ML CdSe layer on 1 μm thick Zn1−xMnxSe buffer layer prepared by molecular beam epitaxy (MBE). The Mn concentration x in the Zn1−xMnxSe buffer was varied from 0.05 to 0.25. The photoluminescence (PL) peaks from CdSe QDs and from Zn1−xMnxSe barrier are clearly observed at zero magnetic field. The PL position of CdSe QDs appears to be systematically shifted toward low energy with increasing Mn concentration in the Zn1−xMnxSe buffer layer. The PL intensity ratio of CdSe QDs with respect to the Zn1−xMnxSe barrier also monotonically increases with Mn concentration x. This systematic behavior observed in the series of CdSe/Zn1−xMnxSe QD systems indicates that the CdSe QD formation strongly depends on the Mn concentration of the Zn1−xMnxSe buffer layer. The observed large Zeeman shift of the QD system in the presence of magnetic field was discussed in terms of the wavefunction overlap of carriers with Mn ions in the barrier.