Interface phenomena at semiconductor heterojunctions: Local-density valence-band offset in GaAs/AlAs

The valence-band offset {Δ}Eᵥ at the lattice-matched GaAs/AlAs(001) interface is derived from highly precise self-consistent all-electron local-density band-structure calculations of the (GaAs)ₙ(AlAs)ₙ(001) superlattices (with n{≤}3). We calculate {Δ}Eᵥ by using the core levels---available uniquely from an all-electron approach---as reference energies. Since these are experimentally accessible quantities, a direct comparison with experiment is, in principle, possible. We find that {Δ}Eᵥ=0.5±{}0.05 eV, in very good agreement with recent experimental results ({Δ}Eᵥ=0.45--0.55 eV). Calculated core-level shifts are also compared with experiment. These results, which are closely related to changes in the charge-density distribution at the interface, contribute to understanding the underlying mechanism of the band discontinuity.