LCAO CALCULATIONS OF SULFUR INTERLAYERS ON GE(001) AND SI(001)-K 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 K-Ge(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, lending to a 1 X 1 S-interlayer o n a bulk terminated semiconductor. Subsequent deposition of K produces a non-disruptive K monolayer in which the K atoms occupy a 'bridge' p osition (corresponding to that of a continued bulk structure). The DOS (density of states) of the K overlayer hows that the surface is metal lic with the Fermi level pinned near the top of the Ge and Si band gap s. (C) 1998 Elsevier Science B.V.