Annealing of overgrown InAs/GaAs quantum dots: A tight-binding study

The electronic and optical properties of quantum dots (QDs) are determined by their atomic structure. A better understanding of this relationship requires input from electronic structure theory. We employ the empirical sp3s* tight-binding approach, including 2nd-nearest-neighbor interactions and spin-orbit coupling, preceded by structural relaxation using a potential of the Abell-Tersoff type. Large systems with up to 106 atoms can be treated using the folded-spectrum method. We are able to treat large systems up to 106 atoms, folded-spectrum method. We apply our method To simulate the intermixing during annealing of InAs QDs in GaAs, we implemented a strain-driven kinetic Monte-Carlo (kMC) method, where the hopping rate of the cation vacancies depends on the differences of the relaxation energy (calculated with the Tersoff potential). Using strain-dependent rates in the kMC-Simulation leads to faster dissolving of the wetting layer. Because of the different shape of the electron and hole wavefunctions, the exciton is associated with a dipole moment which causes the experimentally observed Stark shift. We investigate how the dipole moment of the ground state exciton in a QD depends on the concentration profiles after annealing