EFFECT OF COULOMB ENHANCEMENT ON OPTICAL GAIN IN (ZN,CD)SE ZNSE MULTIPLE-QUANTUM WELLS/

The optical-gain spectra of a 40-Angstrom (Zn,Cd)Se/ZnSe multiple quan tum well has been measured at various temperatures using a variable-st ripe method. By comparison with a gain calculation including many-body effects, we have shown that gain in this structure arises from an ele ctron-hole plasma (EHP) for temperatures higher than 140 K. Excellent agreement between experiment and theory allows us to demonstrate the s ignificance of many-body effects such as carrier dephasing and Coulomb enhancement. The breakdown of the EHP model below 140 K indicates an increasing excitonic contribution.