Near-field optical probing of multi-exciton emission from single InGaAs quantum dots

We investigate the luminescence spectra from single quantum dots using low temperature near-field optical probing spectroscopy. We find that single dots containing a few excitons emit into a discrete set of energy states covering a wide-energy range that reflects the internal confinement potential and exciton occupancy. When the exciton number is large, dot emission is channeled through clusters of well-separated energy states. We study different dots from the same ensemble and correlate their multi-exciton energy structure with their confinement condition and growth formation.