Electronic structure of disordered intrinsic semiconductor and s-d systems: Two-band localisation

Abstract

Electronic structure of disordered two-band systems is investigated by both the direct diagonalisation and the real-space renormalisation method with an emphasis on the interplay of disordered bands connected by the inter-band mixing. The nature of the Anderson-localised states is clarified for the cases of a direct-gap intrinsic semiconductor and a hybridised s-d system. It is shown that, in the case of a semiconductor, there exists a significant correlation in the two-band components of localised states in the pseudo-gap region. In the case of the s-d model, the s band drastically affects the structure of d band, giving rise to eigenstates with characteristic hybridisation.