ELECTRONIC-STRUCTURES OF HETEROVALENT (001) SEMICONDUCTOR SUPERLATTICES - GAP/ZNS AND GAAS/ZNSE

Electronic structures of GaP/ZnS and GaAs/ZnSe (001) heterovalent superlattices with different interface configurations are calculated by the first-principles pseudopotential method. As for superlattices with plane interfaces, it is shown that the appearance of interface states makes these systems direct-pp type-II semiconductors and shows large anisotropy in the conductive and optical properties. Moreover large lattice relaxation is expected to occur at the interface. In superlattices with charge-compensated interfaces, an electric field runs along the interface and a quantum well picture is applicable to the states around the fundamental pp. However the calculated band offsets are strongly dependent on the valency of interface atoms, some of which is compared with experiments.