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

The valence-band offset 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 n3). We calculate Ev by using the core levelsavailable uniquely from an all-electron approachas reference energies. Since these are experimentally accessible quantities, a direct comparison with experiment is, in principle, possible. We find that Ev=0.50.05 eV, in very good agreement with recent experimental results (Ev=0.450.55 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.