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
Titolo: | Radiative recombination processes in wide-band-gap II-VI quantum wells: The interplay between excitons and free carriers |
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Data di pubblicazione: | 1996 |
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Digital Object Identifier (DOI): | http://dx.doi.org/10.1364/JOSAB.13.001268 |
Appare nelle tipologie: | 1.1 Articolo in rivista |