Metallization of the potassium overlayer on the β-SiC(100) c(4 × 2) surface

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 0.0...

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Published inJournal of physics. Condensed matter Vol. 24; no. 48; p. 485001
Main Authors Haycock, Barry J, Trabada, Daniel G, Ortega, José, O'Mahony, J D, Lewis, J P
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 05.12.2012
Institute of Physics
Subjects
Condensed matter
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Density functional theory
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Exact sciences and technology
Impurity and defect levels; energy states of adsorbed species
Metal-insulator transition
Monolayers
Physics
Potassium
Semiconductors
Simulation
Surface and interface electron states
Topology
Ultrathin films
Surface reconstruction
Total energy
Silicon carbide
Surface electron state
Density functional method
Overlayers
Coverage rate
Potassium
Semiconductor metal transition
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Summary: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.
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ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/24/48/485001