Micro-photoluminescence spectroscopy of hierarchically self-assembled quantum dots

Novel, self-assembled quantum dot (QD) structures suitable for single-dot optical spectroscopy are fabricated by combining III–V molecular beam epitaxy and in situ, atomic layer precise etching. Several growth and etching steps are used to produce lateral InAs/GaAs QD bimolecules and unstrained GaAs/AlGaAs QDs with low surface density (≲108cm-2). Micro-photoluminescence is used to investigate the ensemble and single-QD properties of GaAs QDs. Single-QD spectra show resolution-limited sharp lines at low excitation and broad “shell-structures” at high excitation intensity.