Origin of two types of excitons in CdSe dots on ZnSe

Recent micro-FL and time-resolved PL data performed on CdSe dots embedded i n ZnSe show compelling evidence that the FL emission results from two diffe rent kinds of states. We propose a model explaining the origin of these dif ferent states coexisting within a single dot. The main concept of the model is that, while the ground state of the heavy hole is confined to strain-in duced potential pockets at the bottom of the island, the electrons and the first excited state in the valence band are distributed within the entire i sland. That difference in the degree of localization between the two heavy- hole band states is responsible for the different properties of PL transiti ons observed in our experiments.