STRAIN-ENERGY CALCULATIONS OF SURFACE AND STEP STRUCTURES ON SILICON(111)

The Keating strain-energy method has been applied to estimate the energies of step structures on Si(111)2 X 1. Since angular strains are involved which go beyond the applicability limits, which are discussed, of the Keating formula, a correction factor is used, derived by comparing Keating-type calculations of particular surface models of Si(111) with the results of more extensive calculations. It is found that the use of a simple correction factor gives results that agree well with a calculation for the Pandey model and one for the three-bond scission model. Using this factor, a model for a 3-substep structure of the (322) step on Si is found to be quite stable, while the 2-substep structures are moderately stable.