Investigation of carrier relaxation dynamics in single CdSe/ZnSe self-organized quantum dot by time-resolved micro-photoluminescence

We have investigated carrier relaxation dynamics in single CdSe/ZnSe quantum dot (QB) by time-resolved micro-photoluminescence (PL). The discrete sharp lines, originated from individual QD states, exhibit various rise and decay time constants. The decay times of the sharp lines from ground states and excited states are estimated to be 700 similar to 800 psec and 400 similar to 500 psec, respectively, and the rise times of the ground states become longer compared with those of the excited states. These results are in contrast to successive change of the rise and decay times observed in time-resolved macro-PL with varying the detection wavelength. The quasi-continuum higher states with much shorter decay times are clearly observed over the discrete states of the QDs.