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

Abstract

The valence-band offset \ensuremath{\Delta}${E}_{v}$ 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\ensuremath{\le}3). We calculate \ensuremath{\Delta}${E}_{v}$ 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 \ensuremath{\Delta}${E}_{v}$=0.5\ifmmode\pm\else\textpm\fi{}0.05 eV, in very good agreement with recent experimental results (\ensuremath{\Delta}${E}_{v}$=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.