Electronic quantum dot states induced through photon emission

We review the optics of negatively charged excitons in self assembled InAs/GaAs quantum dots. The charging state of a quantum dot was tuned electrostatically in a field effect structure. We investigated in this way the neutral exciton as well as the negatively singly, doubly and triply charged excitons, namely the X⁰, X^1-, X^2- and X ^3- excitons. A Zeeman splitting and a diamagnetic shift in the photoluminescence emission line is clearly observed for X⁰, X ^1- and X^2- exciton as a function of magnetic field. In contrast the triply negatively charged exciton shows a completely different magnetic behaviour. Here, under the influence of a high magnetic field, the quantum dot electronic states are found to be hybridized with the continuum of states in the wetting layer. Such a hybridization turns out to be induced by photon emission of the X^3- exciton. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.