Step-formation energies and domain orientations at Si(111) surfaces

Using an energy-minimization approach, we have examined reconstruction effects for one-broken-bond [$\overline{2}11$] and cleavage-induced, two-broken-bond [$2\overline{11}$]-type steps on the Si(111) surface. For a [$2\overline{11}$] step, we find two inequivalent domain orientations associated with the (2 × 1) reconstruction pattern of the terrace atoms. Moreover, we are able to account for the relative stability of the [$2\overline{11}$] step over the [$\overline{2}11$] step. A spectral analysis of step-related state is presented and compared with recent photoemission measurements.