Dephasing and interaction of excitons in CdSe/ZnSe islands

The dephasing of excitons in self-organized CdSe/ZnSe islands grown by mole cular-beam epitaxy is investigated using spectrally resolved four-wave mixi ng. A distribution of dephasing times is observed, indicating the existence of localized excitons with different relaxation times at comparable transi tion energies. Polarization-dependent measurements identify the formation o f biexcitons. The observed large biexciton binding energy of 22 meV increas es with decreasing exciton energy, which is attributed to an increasing thr ee-dimensional confinement. (C) 2000 Elsevier Science B.V. All rights reser ved.