Free versus localized exciton recombination in Zn1-xCdxSe/ZnSe multiple quantum wells

Time-resolved photoluminescence studies of Zn1-xCdxSe/ZnSe multiple quantum wells as a function of photoinjected carrier density show a typical exciton localization dynamics at all injection levels in the high-x samples (x similar to 0.2-0.3). On the contrary, the low-x samples (x similar to 0.1) exhibit a gradual saturation of the exciton localization process and band-filling behavior with increasing photoinjection. A rate-equation model provides a description of the time-dependent luminescence in all samples and allows a quantitative determination of the concentration of exciton localization centers. (C) 1996 American Institute of Physics.