We examined band discontinuities in AlAs-Ge-GaAs(001) and GaAs-Ge-AlAs(001) single-quantum-well structures, as well as individual isolated Ge-GaAs(001), Ge-AlAs(001), GaAs-Ge(001), and AlAsGe(001) heterojunctions. We found that well-defined inequivalent neutral interfaces are established in III-V/IV/III-V structures for Ge coverages as low as 1-2 monolayers. Deviations from the transitivity and commutativity rules of heterojunction behavior reflect inequivalent local interface environments rather than charged interfaces.
