Selective excitation of the photoluminescence and the energy levels of ultrasmall InGaAs/GaAs quantum dots

The energy levels of nanometer size InGaAs quantum dots epitaxially grown on GaAs by the coherent islanding effect are probed using selectively excited photoluminescence (PL), and PL excitation. A lateral-confinement-induced interlevel spacing of ∼30 meV between the first two states can be deduced from the spectra.