Femtosecond exciton broadening in ternary II-VI semiconductor quantum wells

Femtosecond exciton dynamics are selectively investigated in a ZnCdSe-ZnSe multiple quantum well at low photoexcited carrier density by means of a two -color absorption saturation technique. Broadening of the exciton lines by the photoexcited carriers is found to dominate the observed nonlinear respo nse, with a carrier distribution dependent dynamics indicating that Pauli e xclusion principle effect plays an important role in ternary quantum well s ystems. On a picosecond time-scale, localized excitons modify the nonlinear response, inducing a frequency shift of the absorption change peak as the system approaches quasiequilibrium. (C) 1999 Published by Elsevier Science B.V. All rights reserved.