Longitudinal electric field effects on GaAs-AlAs type-II superlattices

Abstract
We have studied photoluminescence of direct-gap and ‘‘indirect-gap’’ GaAs-AlAs superlattices under electric field perpendicular to the layers. In the former case, the quantum confined Stark effect is observed as expected. In the latter case, reverse effects are found, providing evidence that X-like electron states are confined in the AlAs slabs.