Final state contribution to the Si 2p binding energy shift in SiO 2/Si(1 0 0)

Abstract

The Si 1s and 2p photoemission and the Si KL 2,3L 2,3 Auger emission from SiO 2/Si(1 0 0) surfaces were measured for oxide thicknesses from 0.4 to 3.8 nm using high-energy photoemission ( hν=3000 eV). The energy of the SiO 2 emission depends on the layer thickness. The Si 4+–Si 0 energy differences Δ E 1s, Δ E 2p and Δ E KLL were combined to separate the initial and final state contribution to the energy shift of the Si 4+ 2p line. Within the experimental error, the 2p initial state is constant up to about 2 nm oxide thickness, where differential charging gradually sets in. The observed variation of Δ E 2p is entirely due to final state relaxation. It is found that Δ E 1s−Δ E 2p=0.62 eV, independent of the oxide thickness.