Mixed biexcitons in single quantum wells

Abstract

Biexcitonic complexes in a ZnSe single quantum well are investigated by spectrally resolved four-wave mixing (FWM). The formation of heavy-heavy-hole ${\mathrm{XX}}_{h}$ and of mixed heavy-light-hole ${\mathrm{XX}}_{m}$ biexcitons showing binding energies of ${\ensuremath{\Delta}}_{h}=4.8\mathrm{meV}$ and ${\ensuremath{\Delta}}_{m}=2.8\mathrm{meV}$ is identified by polarization selection rules. The coherent dynamics of the FWM response and the observed FWM intensity ratio between the ${\mathrm{XX}}_{h}$ and ${\mathrm{XX}}_{m}$ biexciton-induced nonlinear signals are in agreement with the solution of an extended optical Bloch equation.