Relevance of the purity level in a MetalOrganic Vapour Phase Epitaxy reactor environment for the growth of high quality pyramidal site-controlled Quantum Dots

We report in this work on the spectral purity of pyramidal site-controlled InGaAs/AlGaAs Quantum Dots grown by metal-organic vapour phase epitaxy on (1 1 1)B oriented GaAs substrates. Extremely sharp emission peaks were found, showing linewidths surprisingly narrow (∼27 μeV) and comparable to those that can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum environment. A careful reactor handling is regarded as a crucial step toward the fabrication of high optical quality systems.