Scanning tunneling microscope study of the c(2×8) ordering in the ``1×1'' phase on the quenched Si(111) surface

Abstract

We study the atomic structure of the c(2\ifmmode\times\else\texttimes\fi{}8) ordering in the ``1\ifmmode\times\else\texttimes\fi{}1'' region on the quenched Si(111) surface to examine the trace of the stacking fault layer formation in the ``1\ifmmode\times\else\texttimes\fi{}1'' region. For the c(2\ifmmode\times\else\texttimes\fi{}8) ordering, two models have been proposed; the dimer chain model with the stacking fault layer and the simple adatom model without the stacking fault layer. Our dual-polarity scanning tunneling microscope images showed that the empty-state protrusion appears at the site adjacent to that of the occupied-state protrusion. This supports the simple adatom model for the c(2\ifmmode\times\else\texttimes\fi{}8) ordering. In the unit cell of c(2\ifmmode\times\else\texttimes\fi{}8), asymmetry in contrast to protrusions was also observed at low bias voltages. This is attributed to the buckling of the rest atom as in the Ge(111)c(2\ifmmode\times\else\texttimes\fi{}8) reconstruction. No trace of the stacking fault layer was found in the c(2\ifmmode\times\else\texttimes\fi{}8) ordering. The trace of the stacking fault layer was found only at the boundary between the ``1\ifmmode\times\else\texttimes\fi{}1'' and the 7\ifmmode\times\else\texttimes\fi{}7 region. At the boundary, the stacking fault layer intruded into the ``1\ifmmode\times\else\texttimes\fi{}1'' region from some corner holes of the edge of the 7\ifmmode\times\else\texttimes\fi{}7 region.