Cooling of an electron-hole plasma in a ${\mathrm{Ga}}_{0.47}$${\mathrm{In}}_{0.53}$As multiple-quantum-well structure

Time-resolved photoluminescence experiments on a ${\mathrm{Ga}}_{0.47}$${\mathrm{In}}_{0.53}$As/${\mathrm{Al}}_{0.48}$${\mathrm{In}}_{0.52}$As multiple-quantum-well structure grown by molecular-beam epitaxy yield a strong dependence of plasma cooling on excitation density. Theoretical fits of the cooling behavior necessitate an enhancement of the polar-optical-phonon scattering time by a factor of 100 when the carrier density is increased from ${10}^{16}$ to ${10}^{18}$ ${\mathrm{cm}}^{\mathrm{-}3}$.