Oxidation of Si(100)2x1: thermodynamics of oxygen insertion and migration

Accurate quantum chemical calculations on model cluster molecules are used to identify and compare the most probable surface structures involved in the oxidation of the Si(100)2 x 1 surface. The energetics of various reaction channels for insertion of oxygen into Si-Si bonds are evaluated. The dimer bond is clearly shown to be the initial target of O entry and an oxygen-inserted dimer is proposed as the most likely structure at lower temperatures. At higher temperatures an asymmetrically oxidized dimer unit with three oxygen atoms inserted into Si-Si bonds at the same silicon is the dominant feature. (C) 1997 Elsevier Science B.V.