Pyramidal quantum dots: High uniformity and narrow excitonic emission

We report on the optical properties of site-controlled InGaAs dots in GaAs barriers grown in pre-patterned, large pitch, pyramidal recesses by metalorganic vapour phase epitaxy. The inhomogeneous broadening of excitonic emission from an ensemble of quantum dots is found to be extremely narrow, with a standard deviation of 1.19 meV. A dramatic improvement in the spectral purity of emission lines from individual dots is also reported (18-30 μeV ) when compared to the state-of-the-art for site controlled quantum dots.