Dynamics of exciton localization in aCdSe0.5S0.5mixed crystal

Dynamic processes of exciton localization in a ${\mathrm{CdSe}}_{0.5}$ ${\mathrm{S}}_{0.5}$ II-VI mixed semiconductor have been studied by time-resolved photoluminescence. We found experimentally that the exciton-transfer rate depicts a power-law behavior near the mobility edge ${\mathit{E}}_{\mathit{m}}$. Our results indicate that the exciton-localization radius behaves according to the law a(E)∼‖${\mathit{E}}_{\mathit{m}}$-E${\mathrm{\Vert }}^{\mathrm{-}\mathit{s}}$ (E≤${\mathit{E}}_{\mathit{m}}$), s being nearly equal to 0.7, which is analogous to the behavior of the localized carriers in the Mott-Anderson model. The spectral shift with delay time has been shown to be a natural consequence of the observed exciton-lifetime behavior.