Localized Biexcitons in Quasi-2D and Quasi-3D Systems

The influence of excitonic localization on the biexcitonic binding energy in quasi-3D and quasi-2D structures is investigated. We consider here localization energies smaller than the exciton binding energy, not significantly changing the exciton internal motion. We show, that the biexciton binding energy increases for localization energies comparable to or larger than the biexciton binding energy. In the limit of large localization energies, the biexciton binding energy reaches about 40% of the exciton binding energy, independent of the initial dimensionality of the system. This is discussed considering the zero-point kinetic energy of the exciton–exciton motion in the biexciton. The biexciton binding energy accordingly shows a dependence on the localization depth and on the shape of the exciton localization potential.