RELAXATION OF HOT EXCITONS IN INHOMOGENEOUSLY BROADENED CDXZN1-XSE ZNSE NANOSTRUCTURES/

The dimensionality dependence of hot exciton relaxation was studied by means of photoluminescence (PL) spectroscopy comparing CdxZn1-xSe/ZnS e quantum wells and quantum dots. In both systems, an efficient popula tion of radiative excitonic ground states via longitudinal-optical (LO ) phonon scattering is observed for an excess energy of the exciting l aser corresponding to an integer number of LO-phonon energies. Thus, o nly selected areas of the inhomogeneously broadened systems contribute to the PL spectrum immediately after the exciting laser pulse. This r esults in a drastical reduction of the PL linewidth. In quantum wells, the redistribution of excitons occurs due to acoustic phonon assisted migration within the CdxZn1-xSe/ZnSe layer. In contrast, this process is found to be substantially suppressed in quantum dots due to the th ree-dimensional exciton confinement.