We study time-resolved emission from self-assembled single InGaAs/GaAs quantum dots by the time-correlated single photon counting method using near-field optical microscopy. The decay time of the emission from discrete levels of a single quantum dot increases with the decrease in the emission energy and with the increase in the excitation intensity. We develop a rate equation model which accounts for the initial filling of the states, cascade relaxation, state filling and carrier feeding from a wetting layer. High collection efficiency of a double-tapered-type fiber probe enables us to study the emission even at very weak excitation intensities. The direct excitation into a single dot is dominant at this excitation level. State filling, cascade relaxation and extra carrier feeding from the wetting layer become pronounced when the excitation intensity increases.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)
- Physics and Astronomy(all)