Recombination Enhancement due to Carrier Localization in Quantum Well Structures

Picosecond luminescence experiments on $\mathrm{GaAs}/{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ quantum well structures reveal a significant influence of localization on the transition probabilities of photoexcited carriers. The spontaneous lifetime of electrons and holes within the quantum well decreases with well thickness $L_z$ from 1 ns for $L_z=14\mathrm{}$ nm to 350 ps for $L_z=5\mathrm{}$ nm because of the enhanced recombination due to localization of the carriers.