Residual thermal desorption study of the room-temperature-formed Sb/Si(111) interface

Abstract

This paper addresses issues of the subtle kinetic changes on the superstructural phase formation in the technologically important Sb/Si system. The thermal stability of the room-temperature (RT) deposited Sb on a $(7\ifmmode\times\else\texttimes\fi{}7)$ reconstructed Si(111) surface by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and electron energy-loss spectroscopy (EELS) is reported. At a very low Sb flux rate of 0.03 ML/min Sb uptake shows that it grows in the Frank--van der Merwe mode yielding a $(1\ifmmode\times\else\texttimes\fi{}1)$ LEED pattern for coverages of 1.0 ML and above. On annealing, AES shows that initially Sb adatoms agglomerate into large islands on top of a stable monolayer, before the Sb islands desorb in the temperature range of $350\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}--480\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, to leave a sharp $(1\ifmmode\times\else\texttimes\fi{}1)$ stable Sb monolayer. Monolayer desorption from about $650\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ results in several surface phases such as $d(2\ifmmode\times\else\texttimes\fi{}1),$ $(5\ifmmode\times\else\texttimes\fi{}5),$ $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{})$ and $(5\sqrt{3}\ifmmode\times\else\texttimes\fi{}5\sqrt{3}\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{}).$ The $(5\ifmmode\times\else\texttimes\fi{}5)$ at 0.4 ML and the $(5\sqrt{3}\ifmmode\times\else\texttimes\fi{}5\sqrt{3}\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{})$ at 0.2 ML are novel phases observed only during this desorption route. However, the 0.5--0.7-ML $(5\sqrt{3}\ifmmode\times\else\texttimes\fi{}5\sqrt{3}\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{})$ phase, observed while desorbing from a 1.0-ML $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{})$ initial phase, is not observed here. The EELS studies show the differences in the surface-related electronic features of the various superstructural phases. The results demonstrate the differences in the superstructural phase formation due to differences in the formation pathways adopted.