LCAO calculations of sulphur interlayers on Ge(001) and Si(001)single bondK interfaces

We present the results of an LD-LCAO (local-density linear-combination-of-atomic-orbitals) study on the effect of introducing an interlayer of S into Ksingle bondGe(001) and Si(001) interfaces. Total energy calculations of the Ge and Si interfaces, indicate that the S interlayer appears to chemically stabilise the interface, leading to a 1 × 1 S-interlayer on a bulk terminated semiconductor. Subsequent deposition of K produces a non-disruptive K monolayer in which the K atoms occupy a ‘bridge’ position (corresponding to that of a continued bulk structure). The DOS (density of states) of the K overlayer shows that the surface is metallic with the Fermi level pinned near the top of the Ge and Si band gaps.