Enhancement of Valence Band Mixing in Individual InAs/GaAs Quantum Dots by Rapid Thermal Annealing

We measure polarization resolved photoluminescence from excitonic complexes in tens of single InAs/GaAs quantum dots (QDs) over a wide range of energies in two samples: one as-grown, the other subjected to rapid thermal annealing (RTA). Using the linear polarization of the X + emission as a probe of the valence band mixing (VBM), we find that RTA enhances QD VBM, attributed to the increase in QD height. We complement our measurements with 8-band $k\cdot p$ calculations, which suggest the increase in height on annealing is responsible for this enhancement.