Onion-like growth of and inverted many-particle energies in quantum dots

By varying the number of shells of the quantum onion, the number of bound states varies. In consequence, the magnitude of many-particle energies like exchange and correlation calculated in the frame of configuration interaction changes dramatically resulting, e.g. in a sign reversal of the biexciton binding energy. This sign reversal is directly observed in single dot spectroscopy using cathodoluminescence employing a shadow mask technique.