Miniband landscape of disordered dimer superlattices

Abstract

We investigate numerically the universal quantum fluctuations of the resistance and conductance in disordered dimer semiconductor superlattices. These systems exhibit sets of extended states (in spite of being disordered) due to the resonance induced by the dimer structure. We show that the transmission amplitude r (E) is a function of the energy of injected electrons and that its main characteristic is a "center" where r(E) ~ 1. This region of energy can be considered as consisting of weakly localized states proper of mesoscopic systems. On the other hand, the landscape of the allowed energies is a complex one, because close to the band edges, where r(E) « I, states are strongly localized. We attempt to understand these two regions by investigating the universal fluctuation properties of the resistance and conductance in both ofthem. We also hope that this study will contribute to the knowledge about universal fluctuations in mesoscopic systems.