Abstract
Selectively excited photoluminescence (PL) measurements are performed for CdSe/ZnSe quantum dots (QDs) in order to clarify the electronic excited states and their relaxation mechanisms. From a contour map of PL intensity of CdSe QDs, it is found that the excitons in CdSe QDs are relaxed by multiple longitudinal-optical (LO) phonon emissions. Most CdSe LO phonons in large QDs and ZnSe LO phonons surrounding smaller QDs contribute to the relaxation processes. Furthermore, since high excited states of QDs strongly interact with each other, PL intensity at low detection energy are enhanced at higher excitation energy. Therefore, the distribution curve of PL intensity associated with the 1-LO-phonon structure is considered to resemble the size distribution curve for CdSe QDs.