Auger-recomination in self-assembled quantum dots

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The Auger-effect is a many-particle scattering effect and of great significance, for instance, in material analysis (Auger-spectroscopy) and in optoelectronic devices where nanoparticles are used as light emitters like the fluorescence medium in commercially available television screens. In such colloidal nanoparticles, the Auger-process is decisive for inefficiencies in the photon conversion process, as the energy gets dissipated non-radiatively. This leads to spectral wandering (shifts of the emission wavelength) and blinking (on- and off-switching of the luminescence) of the nanoparticles. In single self-organized quantum dots, the Auger-effect has been neglected so far. In the presented project, this Auger-effect will be studied in detail in order to a get a deeper understanding of this fundamental effect on a well-known model system of self-assembled quantum dots. For this purpose, various quantum dot structures will be grown, characterized by a range of methods and finally investigated via resonance fluorescence towards their Auger-characteristics. This will be done in close cooperation of two project leaders located at the Ruhr-Universität Bochum and the Universität Duisburg-Essen. Especially sample structures with quantum dots of different size and shape, having different tunnel-coupling to a charge reservoir and an additional super lattice for creation of sub-band states will be grown and measured by resonance fluorescence. Moreover, the influence of external magnetic- and internal electric field on the Auger-recombination rate will be studied. A detailed understanding of the Auger effect in self-organized quantum dots could reveal external or internal tuning knobs to suppress the Auger-recombination and create structures for quantum-light emitters with high intensity and narrow linewidth.