High atom density in the ‘‘1×1’’ phase and origin of the metastable reconstructions on Si(111)

Abstract

We report unambiguous atomic scale evidence demonstrating that the atom density in the ``1\ifmmode\times\else\texttimes\fi{}1'' high temperature phase of Si(111) is \ensuremath{\sim}6% higher than the 7\ifmmode\times\else\texttimes\fi{}7. Such evidence is provided by scanning tunneling microscopy observation of excess adatom density and related island formation on surfaces prepared by a novel method which provides a low step density. The presence of the excess adatom density is also correlated to the observation of areas of metastable reconstructions, i.e., 9\ifmmode\times\else\texttimes\fi{}9, 2\ifmmode\times\else\texttimes\fi{}2, c2\ifmmode\times\else\texttimes\fi{}4, and \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 , much larger than previously reported and for the first time, the existence of metastable 11\ifmmode\times\else\texttimes\fi{}11 on Si(111).