Picosecond charge variation of quantum dots under pulsed excitation

We present a spectroscopic study of excitation dynamics in self-assembled CdTe/ZnTe quantum dots. Insight into details of kinetics is obtained from the time-resolved microphotoluminescence, single photon correlation, and subpicosecond excitation correlation measurements done on single quantum dots. It is shown that the pulsed excitation at an energy above the energy gap of the barrier material results in separate capture of electrons and holes. We found that the capture of electrons by the quantum dot is delayed with respect to the capture of holes: the electron capture takes place in 20–40 ps after the excitation pulse, while the capture of holes is much faster.