Dephasing of negatively charged excitons in ZnMgSe/ZnSe single quantum wells

We investigate the interaction and dephasing of excitons and negatively cha rged excitons (trions) in ZnSe/Zn0.9Mg0.1Se single quantum wells by intensi ty- and temperature-dependent spectrally resolved transient four-wave mixin g. The studies show that the incoherent electrons which are involved in the formation of trions are optically excited from the GaAs substrate. The hom ogeneous linewidths of the exciton- and trion-transition increase with incr easing captured electron density that saturates at high excitation intensit ies. With increasing temperature the electron density in the quantum well i s reduced due to thermal activation and a decrease of the trion peak intens ity and of the exciton and trion homogeneous linewidths is observed. (C) 20 00 Elsevier Science B.V. All rights reserved.