Cascaded exciton emission of an individual strain-induced quantum dot

F. J. R. Schülein, A. Laucht, J. Riikonen, M. Mattila, M. Sopanen, H. Lipsanen, J. J. Finley, A. Wixforth, H. J. Krenner

Applied Physics Letters 95, 083122 (2009)

Single strain-induced quantum dots are isolated for optical experiments by selective removal of the inducing InP islands from the sample surface. Unpolarized emission of single exciton, biexciton, and triexciton transitions are identified by power-dependent photoluminescence spectroscopy. Employing time-resolved experiments performed at different excitation powers, we find a pronounced shift of the rise and decay times of these different transitions as expected from cascaded single photon emissions. Good agreement is found for a rate equation model for a three step cascade.