Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking

A sequence of photoluminescence spectroscopy based methods are used to rigorously identify and study all the main spectral features (more than thirty emission lines) of site controlled InGaAs/AlGaAs quantum dots (QDs) grown along [111]B in inverted tetrahedral pyramids. The studied QDs reveal signatures of one confined electron level, one heavy-hole-like level and one light-hole-like level. The various heavy-light-hole hybrid exciton complexes formed in these QDs are studied by polarization resolved spectroscopy, excitation power dependence, crystal temperature dependence and temporal single photon correlation measurements. The presented approach, which only requires a minimal theoretical input, enables strict spectral identification of the fine structure patterns including weak and spectrally overlapping emission lines. Furthermore, it allows the involved electron-hole and hole-hole exchange interaction energies to be deduced from measurements. Intricate fine structure patterns are qualitatively understood by group theory and shown to be very sensitive to the exact symmetry of the QD. Emission patterns influenced by hole-hole exchange interactions are found to be particularly useful for identifying QDs with high \(C_{3v}\) symmetry and for probing symmetry breaking.