Chemisorption Competition between H₂O and H₂ for Sites on the Si Surface under Xe⁺ Ion Bombardment: An XPS Study

This paper reports the competition of H₂O (residual) and H₂ by site (defects) on the Si surface, created by Xe⁺ ion bombardment. X-ray photoelectron spectroscopy (XPS) in an ultrahigh vacuum system attached to the sample preparation chamber provided the data for the analyses. As hydrogen cannot be detected by XPS, an indirect method to evaluate the O and H cover ratio was developed. The hydrogen passivation effect obtained by the formation of the Si-H bond due to H₂ chemisorption limits Si-OH and Si-O-Si bonds, which are products of H₂O dissociation. In addition, the results have shown that Xe⁺ ion bombardment diminished the H₂ chemisorption energy barrier onto Si.