Excitonic states in GaAs quantum dots fabricated by local droplet etching

Abstract

The influence of dot size and shape on the excitonic structure of GaAs/AlGaAs quantum dots (QDs) is studied experimentally and theoretically. Almost strain-free GaAs QDs are fabricated by epitaxially filling of nanoholes in an AlGaAs surface. The nanoholes are formed in a self-assembling fashion by local droplet etching. As an important point, the size of the QDs can be adjusted by the hole filling level. As a consequence, the exciton recombination energy can be controllably varied over a range of 130 meV by the dot size. We present micro- and macro-photoluminescence measurements of the $s$-shell recombinations. With the hole shape determined using atomic force microscopy and the amount of GaAs filled into the holes, we have quite precise input parameters for a simulation of the excitonic states in the QDs. The measured exciton and biexciton recombination energies are well reproduced by calculations based on eight band $\mathbit{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{p}$ theory and configuration interaction scheme with a deviation of less than 7 meV.