Polarization spectra of quantum wells with imperfect-grid insertions

By perturbation theory it is demonstrated that elongated island structures in submonolayers of AlAs inserted into GaAs/AlAs quantum wells cause anisotropies in the optical-polarization spectra. Therefore, measured optical anisotropies alone do not furnish sufficient proof of lateral quantum confinement. Ordering the islands into even a very imperfect grid structure significantly enhances the magnitude of the optical anisotropies when the grid spacing and the quantum-well width are chosen appropriately.