Surface and bulk core-level shifts of the Si(111)<i>√3 √3</i>-Ag surface: Evidence for a charged<i>√3 √3</i>layer

Abstract

Si 2p and Ag 4d photoelectron spectra have been measured for the Si(111)\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 -Ag surface at both surface- and bulk-sensitive photon energies. A dramatic shift of the bulk Si 2p component for the \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 surface has been observed and is attributed to the presence of an inherently charged \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 layer. A single component of surface Si 2p levels is found for the \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 surface. Discussion of structural and growth models of the \ensuremath{\surd}3 -Ag surface is made.