Deformations of the surface-state band of clean Si(001) surfaces due to roughening and misorientation

Abstract
The shapes of the dangling-bond occupied-state band of various clean Si(001) surfaces are deduced from high-resolution photo-emission yield spectra. These are analysed in terms of three components, respectively 0.2, 0.45 and 0.75 eV below the valence band edge. The variations when the sample undergoes vacuum annealing or an oxidation-de-oxidation cycle of the (001) and vicinal faces are correlated with the smoothing or roughening of the surface on the atomic scale. The ionisation energy is found to be 5.30+or-0.05 eV whatever the surface roughness.