Tin-induced reconstructions of the Si(100) surface.

Abstract

The behavior of tin on the Si(100) 2\ifmmode\times\else\texttimes\fi{}1 surface has been studied using scanning tunneling microscopy. At room temperatures (T150 \ifmmode^\circ\else\textdegree\fi{}C), low coverages of Sn form dimer rows that are oriented perpendicular to the underlying Si dimer rows. As the coverage is increased, these rows pack into areas of two-dimensional order, forming small regions of 2\ifmmode\times\else\texttimes\fi{}2 near 0.5 monolayer (ML). For substrates annealed above 500 \ifmmode^\circ\else\textdegree\fi{}C, the following reconstructions are known to occur: c(4\ifmmode\times\else\texttimes\fi{}4) and 2\ifmmode\times\else\texttimes\fi{}6 below 0.5 ML, c(4\ifmmode\times\else\texttimes\fi{}8) for 0.5--1.0 ML, and 1\ifmmode\times\else\texttimes\fi{}5 for 1.0--1.5 ML. A number of structures are observed by scanning tunneling microscopy which are associated with these reconstructions. Both the c(4\ifmmode\times\else\texttimes\fi{}4) and 2\ifmmode\times\else\texttimes\fi{}6 phases consist of missing Si dimer trenches and stripelike structures which grow perpendicular to the Si dimer rows. As the coverage is increased, the c(4\ifmmode\times\else\texttimes\fi{}8) reconstruction occurs when chainlike structures, consisting of buckled Sn dimers, form on the surface between trenches. The 1\ifmmode\times\else\texttimes\fi{}5 phase then grows over this c(4\ifmmode\times\else\texttimes\fi{}8) layer and consists of bright features which are probably associated with Sn dimers. When more than 2 ML Sn is deposited and annealed, the surface undergoes a gross rearrangement and forms {311} facets.