Influence of exciton ionization on recombination dynamics inIn0.53Ga0.47As/InP quantum wells

We have investigated the carrier dynamics in ${\mathrm{In}}_{0.53}$ ${\mathrm{Ga}}_{0.47}$As/InP quantum wells with various well widths as a function of temperature and carrier density using time-resolved photoluminescence spectroscopy. At low temperatures (T<50 K), we find pure excitonic recombination. At elevated temperatures, two radiative recombination paths are present, and the proportion of free-carrier recombination to excitonic recombination increases as the temperature is raised. We observe a nonlinear increase of the radiative lifetime caused by thermal ionization of excitons. Exciton binding energies in the range between 9 and 15 meV and majority carrier concentrations of about 1.2×${10}^{10}$ ${\mathrm{cm}}^{\mathrm{-}2}$ are deduced from the ratio between the high and low injection lifetimes. The exciton binding energy increases with decreasing well thicknesses, in good agreement with theoretical predictions.