Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and DFT calculations

Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and DFT calculations, 2010, Physical Review B. The Si 2p and Ge 3d core levels are investigated on the c͑4 ϫ 2͒ reconstructed surfaces of Si͑001͒ and Ge͑001͒, respectively. Calculated surface core-level shifts are obtained both with and without final state effects included. Significant core-level shifts are found within the four outermost atomic layers. A combination of the theoretical results and high-resolution photoemission data facilitates a detailed assignment of the atomic origins of the various components identified in the core-level spectra of both Si͑001͒ and Ge͑001͒.