Atomic structure of Si{001}2×1

Abstract

New experiments on reconstructed Si{001}2×1 and their analysis by low-energy electron diffraction (LEED) are reported. A new structural model containing asymmetric and buckled dimers and strains extending to three and four atomic layers is presented, which fits the LEED data substantially better than any other model tested. The new structure involves a dimer length of 2.54 Å, an average contraction of first-layer spacing of 8%, and three asymmetric displacements of the dimer atoms. A detailed discussion of the needed intensity-averaging procedures among eight equivalent domains is presented. Two theoretical structural models for Si{001}2×1 developed by others on the basis of minimization of total energy are shown to fail the LEED test.