EXCITON SATURATION IN ROOM-TEMPERATURE GAAS ALGAAS MULTIPLE-QUANTUM WELLS/

We report time resolved studies of optically induced circular dichrois m in room temperature GaAs/AlGaAs multiple quantum wells to resolve sp in-dependent and spin-independent contributions to exciton saturation. Phase-space filling and Coulomb contributions were separated by spin dependence while the effects of broadening and screening were distingu ished using different pulse bandwidths. Bound and free carrier contrib utions were compared bq observing the temporal dependence of the circu lar dichroism on femtosecond timescales, The spin independent contribu tion to exciton saturation was found to be independent of whether the carriers were bound or free. (C) 1997 American Institute of Physics.