Electronic and vibrational properties of initial-stage oxidation products on Si(111)-(7x7)

Abstract

Chemisorption of O-2 molecules on the adatom site of Si(111)-(7X7) has been studied by density-functional theory calculations for all possible dissociation configurations. Structures possessing an oxygen atom on top of the Si adatom are all found to be metastable and account well for the metastable electronic and vibrational spectra observed in previous experiments, while structures with only oxygen atoms inserted into the adatom back bonds appear quite stable. The present structural models therefore are all compatible with either the metastable or the stable O-2 reactions products found in this system. The calculated decay pathways of the metastable structures provide additional informations useful for identifying the experimental metastable structures.