Decay Processes of Si 2s Core Holes in Si(111)-7 × 7 Revealed by Si Auger Electron Si 2s Photoelectron Coincidence Measurements

Decay processes of Si 2s core holes in a clean Si(111)-7 × 7 surface are investigated using coincidence measurements of Si Auger electrons and Si 2s photoelectrons at a photon energy of 180 eV. We show that Si 2s core holes exhibit two nonradiative decay processes: the first being a Si L1L23V Coster–Kronig transition followed by delocalization of the valence hole and Si L23VV Auger decay, and the second being Si L1VV Auger decay. The branching ratio of the Si L1L23V Coster–Kronig transition to the Si L1VV Auger decay is estimated to be 96.7% ± 0.4% to 3.2% ± 0.4%.