Using density functional theory slab calculations, an investigation was made of the effect of surface passivation on vacancy and interstitial annihilation on the Si(001) surface. It was found that interstitials and vacancies were both stabilized at the clean and H-/Cl-terminated surfaces, with an energy gain of about 2-3eV relative to those at the fifth sub-surface layer where the surface effect became insignificant. This suggested that the Si surface was an effective sink for vacancies and interstitials, irrespective of surface passivation. However, the calculations showed that the stability of vacancies and interstitials within the topmost 3 sub-surface layers was greatly influenced by surface passivation; due to strong interactions with surface Si dangling orbitals and to the rearrangement of surface atoms in the clean-surface case. The chemical effect of adsorbates itself appeared to be unimportant to defect surface annihilation.

Surface Chemistry Effects on Vacancy and Interstitial Annihilation on Si(001). T.A.Kirichenko, S.K.Banerjee, G.S.Hwang: Physica Status Solidi B, 2004, 241[10], 2303-12