Atomic structure of the Sb-terminated Si(111) surface: A photoelectron diffraction study

Abstract

The deposition under certain conditions of antimony on a $\mathrm{Si}(111)7\ifmmode\times\else\texttimes\fi{}7$ surface removes the $7\ifmmode\times\else\texttimes\fi{}7$ reconstruction, producing a passivated Si(111)-$(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$-Sb (1 monolayer) surface. In this work, a quantitative determination of the atomic structure of this reconstruction using photoelectron diffraction is reported. In particular, high-energy photoelectron diffraction (forward-focusing regime) has been applied to investigate the stacking sequence of the atomic layers of the silicon substrate, and scanned-energy photoelectron diffraction (backscattering regime) has been used to determine quantitatively the atomic structure of the surface. Our results show that the formation of a $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$ phase produces a bulklike-terminated $\mathrm{Si}(111)1\ifmmode\times\else\texttimes\fi{}1$ substrate free of stacking faults. Regarding the atomic structure of the interface, this study strongly favors the $T4$-site milkstool model over the $H3$ one.