Atomic segregation and the optical properties of GaAs/AlAs heterostructures

Atomic segregation is a surface chemical phenomenon which may prevent the a bruptness and structural perfection of epitaxially grown heterointerfaces. Contrary to atomic interdiffusion, segregation at GaAs/AlAs (001) heteroint erfaces is not symmetric regarding which material is deposited first: GaAs- on-AlAs interfaces are not equivalent to AlAs-on-GaAs. Adopting a real-spac e supercell approach, we investigate optical signatures of segregation-indu ced phenomena in short-period superlattices and quantum wells. The atomic-s cale configurations are generated through a kinetically limited segregation model which allows for vertical and lateral atomic exchanges. We show that segregation in general degrades the light-emission properties of GaAs-base d structures, but in some cases it may contribute to improve them.