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

Growth of quantum dots by MOCVD can be now controlled such that the typical mode resulting in a large inhomogeneous, but continuous distribution of QD sizes and shapes switches to an onion-like one. A manifold of narrow distributions differing in size by exactly one monolayer results. Luminescence and excitation spectroscopy beautifully demonstrate this monolayer size-splitting by multimodal spectra whose peaks are in quantitative agreement with our numerical predictions based on eight-band k·p theory implemented using the method of finite differences. ying 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.