# Excitons in quantum dots and design of their environment

Löbl, Matthias Christian. Excitons in quantum dots and design of their environment. 2019, Doctoral Thesis, University of Basel, Faculty of Science.

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Official URL: http://edoc.unibas.ch/diss/DissB_13645

Even when the quantum dots have a large distance to surfaces, coupling to interfaces within the semiconductor heterostructure can be a problematic source of noise and decoherence. For InGaAs quantum dots, the so-called wetting layer is an interface that forms during the growth of the quantum dots and is located in their direct spatial proximity. The continuum states of the two-dimensional wetting layer are energetically close to the $p$- and $d$-shells of the quantum dots. Problematic coupling between quantum dot and wetting layer states takes place for charged excitons. The second part of this work shows that a slight modification to the growth process of the quantum dots removes wetting layer states for electrons. The wetting-layer free quantum dots can contain more electrons than conventional InGaAs quantum dots and the linewidths of highly charged excitons significantly improve. Importantly, these quantum dots retain other excellent properties of conventional InGaAs quantum dots: control of charge and spin state, and narrow linewidths in resonance fluorescence.