Time-resolved studies of single semiconductor quantum dots

We present time-resolved optical studies of single self-assembled quantum d ots. The dots were obtained by Stranski-Krasranow growth of InP on Ga0.5In0 .5P. A selective technique based on etching after electron-beam lithography , combined with the use of an optical microscope to enhance the spatial res olution of a time-resolved photoluminescence system, enabled the observatio n of single quantum dots. The emission linewidth of a single InP dot is obs erved to be around 3 meV. The evolution of the time-resolved photoluminesce nce spectra was studied as a function of excitation intensity. Under intens e pulsed excitation the decay is no more a simple exponential due to feedin g from higher energy levels, as a result of state filling. A four-level rat e equation system is successfully used to model the results. [S0163-1829(99 )06204-9].