The role of Pb wetting layer conduction in tunneling spectroscopy of Pb nanoislands on Si(1 1 1) surface

We have experimentally determined that a Pb wetting layer grown on Si(1 1 1)-7 × 7 is conductive, while In and Ag wetting layers are not, despite the fact that they are all made of metallic atoms. We have further demonstrated that the conduction of the Pb wetting layer at low temperatures plays an important role for the study of low temperature tunneling spectroscopy of metal nanostructures formed on Si(1 1 1) substrates.