OPTICAL INVESTIGATION OF CARRIER TUNNELING IN SEMICONDUCTOR NANOSTRUCTURES

The tunneling dynamics of excitons and free carriers in AlxGa1-xAs/GaA s asymmetric double quantum well and near-surface quantum well structu res has been investigated by means of time-resolved optical techniques . The competing processes of carrier tunneling out of the quantum well and exciton formation and recombination inside the quantum well have been thoroughly studied in the range of the excitation densities relev ant to device applications. A consistent picture capable of fully desc ribing the carrier and excition-tunneling mechanisms in both types of structures has been obtained and apparently contrasting results in the recent literature are clarified.