Topmost-surface-sensitive Si-2p photoelectron spectra of clean Si(100)-2×1 measured with photoelectron Auger coincidence spectroscopy

Topmost-surface-sensitive Si-2p photoelectron spectra of a clean Si(1 0 0)-2 × 1 surface have been measured using Si-2p photoelectron Si-L 23 VV Auger coincidence spectroscopy (Si-2p–Si-L 23 VV PEACS). The escape depth of the PEACS electrons is estimated to be ∼1.2 A. The results support the assignments of the Si up-atoms, the Si down-atoms, the Si 2nd-layer, and the Si bulk proposed in previous researches. The Si-2p component with a binding energy of −0.23 eV relative to the bulk Si-2p 3/2 peak, is shown to originate mainly from the topmost surface. Site selectivity of PEACS is indicated to be achieved to some degree by carefully selecting the kinetic energy of the Auger electrons. Since PEACS can be applied to any surface, the present study opens a new approach to identify PES components.