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

Using an energy-minimization approach, we have examined reconstruction effects for one-broken-bond [2̄11] and cleavage-induced, two-broken-bond [2-11]-type steps on the Si(111) surface. For a [2-11] 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 [2-11] step over the [2̄11] step. A spectral analysis of step-related state is presented and compared with recent photoemission measurements.