Intermixing in quantum-dot ensembles with sharp adjustable shells

State-filling spectroscopy is used to study the effects of alloy intermixing in quantum-dot (QD) ensembles having well-defined electronic shells. Rapid thermal annealing is performed on samples of self-assembled QDs grown with different intersublevel energy spacings. For InAs/GaAs QDs, the intersublevel is tuned between similar to 90 and 25 meV. The intense and sharp shell structures observed in photoluminescence indicate unambiguously that the QDs retained their zero-dimensional density of states after the diffusion of the potential, which also causes strong blueshifts (up to similar to 200 meV) and a pronounced narrowing of the inhomogeneously broadened emission (down to similar to 12 meV). (C) 1999 American Institute of Physics. [S0003-6951(99)00942-0].