Influence of confinement on biexciton binding in semiconductor quantum dot ensembles measured with two-dimensional spectroscopy

The emission energy dependence of the biexciton binding energy is investigated in three semiconductor quantum dot (QD) systems that exhibit different quantum well -> QD confinement. Using two-dimensional Fourier-transform spectroscopy, we demonstrate that in strongly confining InAs QDs, the binding energy is independent of exciton emission energy and fluctuations in the ground state -> exciton transition energy are strongly correlated with those of the exciton -> biexciton. In contrast, the biexciton binding energy increases with emission energy in weakly confining interfacial GaAs QDs, and the level of correlation of exciton-biexciton broadening is reduced. A comparison with simulations reveals the significance of the strength and nature of confinement on Coulomb interactions responsible for biexciton renormalization. DOI: 10.1103/PhysRevB.87.041304