First principles study of Al–Si nanosized clusters on Si(1 0 0)-2×1

Ab initio local density approximation calculations were performed to investigate the energetics and atomic structures of Al–Si nanosized clusters on Si(1 0 0)-2×1. The transition from the Al-2×2 surface phase to Al–Si nanosized clusters has been found energetically favorable. Three different cluster models were considered. The first one was proposed by Kotlyar et al. The second model was proposed by Bunk et al. for the Si(1 0 0)-In system and was adopted by Cocoletzi and Takeuchi for Si(1 0 0)-Al(3×4) reconstruction. Third model is the mixture of the first and second. It has a pyramidal form like the Bunk–Cocoletzi cluster, but eight Al atoms like Kotlyarʹs cluster. The Bunk–Cocoletzi model has been found the most favorable.