Effect of spin-dependentMn2+internal transitions inCdSe∕Zn1−xMnxSemagnetic semiconductor quantum dot systems

Abstract

CdSe quantum dots (QDs) in a ZnMnSe diluted magnetic semiconductor (DMS) matrix were investigated using both energy- and polarization-selective magneto-photoluminescence (PL). The peaks from ${\mathrm{Mn}}^{2+}$ internal transition, CdSe QDs, and ZnMnSe barrier were observed in the experiment done using above-barrier excitation. By examining the dependence of the PL peak intensity on magnetic field we were able to identify the competition between the Auger-type energy transfer process (i.e., the energy transfer from band electrons to ${\mathrm{Mn}}^{2+}$ ions) and energy relaxation into CdSe QDs in this QD system. The role of energy transfer processes between band electrons and ${\mathrm{Mn}}^{2+}$ ions in the DMS QDs was further studied by using excitation energy below the ZnMnSe band gap, where no change in the intensity of internal ${\mathrm{Mn}}^{2+}$ transitions with magnetic field was observed, indicating that the energy transfer from carriers excited into the ZnMnSe barrier is indeed responsible for the intensity behavior of these internal ${\mathrm{Mn}}^{2+}$ transitions observed in DMS QD structures.