In and Si adatoms onSi(111)5×2-Au: Scanning tunneling microscopy and first-principles density functional calculations

Abstract

Structural properties of monatomic indium chains on $\text{Si}(111)5\ifmmode\times\else\texttimes\fi{}2\text{-Au}$ surface are investigated by scanning tunneling microscopy (STM) and first-principles density functional calculations (DFT). The STM topography data show that submonolayer coverage of indium leads to a well-ordered chain structure with the same periodicity as the Si adatoms form on $\text{Si}(111)5\ifmmode\times\else\texttimes\fi{}2\text{-Au}$ surface. Bias-dependent STM topography and spectroscopy reveal two different mechanisms of In-atoms adsorption on the surface: bonding to Si adatoms and substitution for Si atoms in the adatom positions. Those mechanisms are further corroborated by DFT calculations. The obtained structural model of In-modified $\text{Si}(111)5\ifmmode\times\else\texttimes\fi{}2\text{-Au}$ surface remains in good agreement with the experimental data.