ROLE OF SYMMETRY REDUCTION IN THE POLARIZATION DEPENDENCE OF THE OPTICAL-ABSORPTION IN NON-COMMON-ATOM SUPERLATTICES

Ab initio calculations of the dielectric tensor elements show that the mechanism underlying the experimentally observed giant polarization a nisotropy of the optical absorption in non-common-atom superlattices i s a ''selection rule'' by which the radiation polarization along the 1 10 or -110 directions chooses only one transition of the doublet degen erate in common-atom superlattices. The magnitude of the anisotropy de pends only on the energy splitting between the two hole states. Our re sults suggest ways to enhance the anisotropy through manipulation of i nterface structure or chemistry or strain condition.