Atomic structure of the Si(001)c(4 x 2) surface.

Abstract

We have studied the atomic structure of the Si(001)c(4\ifmmode\times\else\texttimes\fi{}2) surface with kinematic low-energy electron diffraction calculations compared with the constant-momentum-transfer-averaged low-energy electron diffraction intensity curves collected by Webb et al. The results show that the reconstruction mechanism of the surface is unbuckled dimerization, that the c(4\ifmmode\times\else\texttimes\fi{}2) reconstruction extends to about the sixth atomic layer, and that there is an oscillatory multilayer relaxation in the surface. We present a model for the atomic structure of the surface which gives a reasonably good agreement with the experimental curves.