Polarization and excitation power-dependent photoluminescence of magnetic/non-magnetic coupled quantum dots

Abstract

The magneto photoluminescence experiments have been performed on a Coupled quantum clots (QDs) system composed of CdSe and CdMnSe QD double layers. The Photoluminescence peaks from two QD layers forms a wide PL band due to the inhomogeneous broadening of QD ensemble in the Coupled QD system. The intensity of the PL band undergoes significant change when a magnetic Held is applied. Specifically, the QD system shows large difference in intensity between sigma and sigma(+) circular polarizations,, which results from the Spill polarization of carriers in the presence of magnetic field. Interestingly, while the lower energy side of the PL. band was dominated by the sigma(+) circular polarization, the higher energy side of the band was dominated by the sigma(+) circular polarization. Furthermore, the relative PL intensity at the low energy side of the band remarkably increases with decrease in excitation power for the sigma(+) circular polarization, while it showed no significant change for a circular polarization. Such polarization and excitation power-dependent behaviors of PL intensity enable us to identify the relative potential profile of the magnetic/non magnetic coupled QD systems. (C) 2008 Elsevier B.V. All rights reserved.