Initial oxidation features of Si(100) studied by Si2p core-level photoemission spectroscopy

The oxygen adsorption processes during the initial oxidation of Si(100) have been investigated by high-resolution photoemission spectroscopy of the Si2p core levels. The variation of the Si2p intensities was measured in detail for the different sub-oxide (Si1+, Si2+, Si3+, and Si4+) components. The oxygen adsorption processes at room temperature during the initial oxidation were quantitatively analyzed by measuring the intensity ratios of each sub-oxide component as a function of the oxidation time. It is found that the Si1+ and Si2+ species are localized mostly at the first interfacial layer, while the Si3+ and Si4+ components exist in the two-dimensional islands with certain height on the initial oxidation layer, and are expanded horizontally during further oxidation. Our results suggest that the two-dimensional island nucleation occurs during the initial oxidation. (C) 2001 Elsevier Science B.V. All rights reserved.