title: Metallization of the potassium overlayer on the β-SiC(100) c(4 × 2) surface.
abstract: We present new data on the potassium-induced semiconducting to metallic transition of the silicon-terminated β-SiC(100) c(4 × 2) surface, resulting from density functional theory simulations. We have analysed many different SiC(100)-K surface topologies, corresponding to K coverages ranging from 0.08 to 1.25 monolayers (ML), paying special attention to the 2/3 ML and 1 ML cases where a metal-insulator transition has been reported to occur. We find that the SiC(100)-K surface is metallic in all the cases. In spite of that, the potassium layer shows a very low density of states in the semiconductor gap up to potassium coverages of ~1 ML, beyond which the potassium layer undergoes a transition to metallic behaviour, explaining the experimental observation. We propose a new atomic model for the surface reconstruction of the 1 ML case which is lower in total energy than the previously suggested model based on linear potassium chains.
authors.affiliation: School of Physics, Dublin Institute of Technology, Dublin 2, Ireland. barry.haycock@mail.wvu.edu
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Haycock
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Trabada
authors.forename: José
authors.initials: J
authors.lastname: Ortega
authors.forename: J D
authors.initials: JD
authors.lastname: O'Mahony
authors.forename: J P
authors.initials: JP
authors.lastname: Lewis