Electronic structure of intentionally disordered AlAs/GaAs superlattices

摘要

We use realistic pseudopotentials and a plane-wave basis to study theelectronic structure of non-periodic, three-dimensional, 2000-atom(AlAs)_n/(GaAs)_m (001) superlattices, where the individual layer thicknessesn,m = {1,2,3} are randomly selected. We find that while the band gap of theequivalent (n = m = 2) ordered superlattice is indirect, random fluctuations inlayer thicknesses lead to a direct gap in the planar Brillouin zone, strongwavefunction localization along the growth direction, short radiativelifetimes, and a significant band-gap reduction, in agreement with experimentson such intentionally grown disordered superlattices.