Huge electric fields in Ge/GaAs (001) and (111) superlattices and their effect on interfacial stability

Self-consistent relativistic pseudopotential calculations of Ge₆/(GaAs)₃ (001) and (111) superlattices yield a sawtooth potential resulting in electric fields of magnitude 10⁹ V/m. This has little effect on the (111) energy bands but localized states on the two (001) interfaces are shifted in opposite directions, resulting in a negative energy gap. Formation-enthalpy calculations indicate the (111) interface is probably stable against reconstruction while the (001) interface is probably unstable.