Band-Edge Electroabsorption in Quantum Well Structures: The Quantum-Confined Stark Effect

We present theory and extended experimental results for the large shift in optical absorption in GaAs-AlGaAs quantum well structures with electric field perpendicular to the layers. In contrast to the Stark effect on atoms or on excitons in bulk semiconductors, the exciton resonances remain resolved even for shifts much larger than the zero-field binding energy and fields > 50 times the classical ionization field. The model explains these results as a consequence of the quantum confinement of carriers.