RECOMBINATION MECHANISMS AND LASER ACTION IN OPTICALLY PUMPED ZnCdSe/ZnSe QUANTUM WELL STRUCTURES

Photoluminescence and magnetoluminescence spectroscopy as a function of the photogeneration rate have been performed to investigate the main recombination mechanisms occurring in Zn0.9Cd0.1Se/ZnSe multiple quantum well structures (MQWS). The photopumped spontaneous and stimulated emission has been studied to elucidate the actual excitonic or free carrier nature of the recombination mechnisms at low temperatures. We observe that lasing originates from free-carriers transitions, although the main spontaneous recombination processes have excitonic character.