Modification of energy relaxation of InGaAs quantum dots by postgrowth thermal annealing

Energy relaxation channels of carriers in InGaAs quantum dots (QDs) by multiphonon processes are observed to be changed upon post growth annealing. Self-organized InGaAs QDs in GaAs grown by MOCVD using the Stranski Krastanow (SK) growth mode were systematically thermally treated. The samples were investigated using photoluminescence (PL) and selectively excited photoluminescence (SPL). Upon annealing, the energy states shift towards higher energies, the inhomogeneous broadening is reduced and the phonon energy is changed drastically. It is shown that the changes of the phonon energy are not alone caused by a variation of the In content and the size of the QDs. The Interface phonons is proposed to be the main reason for the changes of the phonon energy.