EXCITON DYNAMICS IN DISORDERED QUANTUM-WELLS - LOCALIZED AND DELOCALIZED REGIMES

The electronic states in a disordered solid may be localized or deloca lized, depending on their energy and the disorder potential. By examin ing exciton dynamics with transient four-wave mixing experiments we sh ow that low-energy excitons in CdTe/(Cd,Mg)Te quantum wells are locali zed, while higher-energy excitons are not. In the delocalized regime t he excitonic dephasing rate decreases with increasing energy, a theore tically predicted, but experimentally unreported result.