We investigated the excitonic or free-carrier nature of lasing in ZnCdSe/ZnSe quantum wells through stimulated emission measurement in high magnetic field and at by pump-probe nonlinear transmission. A free-exciton to free-carrier gas-phase transition with increasing photoinjected density was found to determine the recombination mechanism responsible for lasing. A self-consistent theory based on the mass-action law, including many-body renormalization of the exciton binding energy and of the hot-carrier effects, was used to extract the phase diagram of the exciton -plasma gas from the pump-probe experiments. In deeper walls exciton localization at sample inhomogeneities is demonstrated by time-resolved photoluminescence experiments. Correspondingly, the exciton to free-carrier phase transition does not change the dominant excitonic character of lasing, which reflects the increasing screening threshold of localized excitons. (C) 1996 Optical Society of America

Radiative recombination processes in wide-band-gap II-VI quantum wells: The interplay between excitons and free carriers

LA ROCCA, Giuseppe Carlo
1996

Abstract

We investigated the excitonic or free-carrier nature of lasing in ZnCdSe/ZnSe quantum wells through stimulated emission measurement in high magnetic field and at by pump-probe nonlinear transmission. A free-exciton to free-carrier gas-phase transition with increasing photoinjected density was found to determine the recombination mechanism responsible for lasing. A self-consistent theory based on the mass-action law, including many-body renormalization of the exciton binding energy and of the hot-carrier effects, was used to extract the phase diagram of the exciton -plasma gas from the pump-probe experiments. In deeper walls exciton localization at sample inhomogeneities is demonstrated by time-resolved photoluminescence experiments. Correspondingly, the exciton to free-carrier phase transition does not change the dominant excitonic character of lasing, which reflects the increasing screening threshold of localized excitons. (C) 1996 Optical Society of America
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11384/5841
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