Structure and photoluminescence of single AlGaAs/GaAs quantum dots grown in inverted tetrahedral pyramids

Arrays of single GaAs/AlGaAs quantum dot (QD) heterostructures grown by organometallic chemical vapor deposition in inverted tetrahedral pyramids on {111}B GaAs substrates are investigated. Cross-sectional atomic force microscopy images evidence a pronounced thickening of the GaAs quantum well layer at the tip of the pyramid, giving rise to a lens-like QD structure. Low-temperature photoluminescence and cathodoluminescence spectra show distinct luminescence from the dots, exhibiting filling of QD states separated by 33 meV at increased carrier densities. Luminescence linewidths of 15 meV and line energy variations of less than 5 meV are obtained across mm2 sample areas.