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

Abstract

The emission energy dependence of the biexciton binding energy is investigated in three semiconductor quantum dot (QD) systems that exhibit different quantum well $\ensuremath{\rightarrow}$ 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 $\ensuremath{\rightarrow}$ exciton transition energy are strongly correlated with those of the exciton $\ensuremath{\rightarrow}$ 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.