Hydrogen at the surface and interface of metals on Si(111)

Abstract

The depth-resolved measurement of hydrogen using the resonant nuclear reaction of ${}^{1}{\mathrm{H}(}^{15}{\mathrm{N},\mathrm{\ensuremath{\alpha}}\mathrm{\ensuremath{\gamma}})}^{12}\mathrm{C}$ in the formation of (Pb, Ag, and Cu)/Si(111) interfaces is reported. It was found that Pb deposition on $\mathrm{Si}(111)1\ifmmode\times\else\texttimes\fi{}1\ensuremath{-}\mathrm{H}$ at 110 and 360 K leads to the formation of the Pb/H/Si(111) interface. Upon deposition of Ag at 110 K, however, it was found that a quarter of the monolayer of H migrates to the surface of Ag with the rest of H remaining at the Ag/Si(111) interface. The preadsorbed H atom was desorbed from the surface by deposition of Ag and Cu at 360 K, suggesting that (Ag, Cu)/H/Si(111) is a metastable structure. The relative stability of the interface H is discussed.