Dense single-atomic 14×3-reconstructed Pb layer on Si(111): Structural and superconducting properties

A highly ordered, Pb-dense $14\ifmmode\times\else\texttimes\fi{}\sqrt{3}$-Pb overlayer was grown on Si(111) using the two-step procedure with formation of the $\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\text{\ensuremath{-}}\mathrm{Pb}$ surface [displaying the $1\ifmmode\times\else\texttimes\fi{}1$ structure at room temperature (RT)] at the first step and RT deposition of additional Pb at the second step until formation of the $14\ifmmode\times\else\texttimes\fi{}\sqrt{3}\text{\ensuremath{-}}\mathrm{Pb}$ phase with 1.286 monolayers of Pb is completed. The single-domain orientation of the $14\ifmmode\times\else\texttimes\fi{}\sqrt{3}\text{\ensuremath{-}}\mathrm{Pb}$ layer persists along the entire surface of the terraces which are typically as wide as dozens of nanometers and in the selected areas might exceed a hundred nanometers. The $14\ifmmode\times\else\texttimes\fi{}\sqrt{3}\text{\ensuremath{-}}\mathrm{Pb}$ phase hosts the superconductivity with the critical temperature ${T}_{c}=2.08$ K which exceeds all ever reported values for the single-atom Pb layers on Si(111).