Chemically prepared, long range ordered, ideally hydrogen terminated Si(111) surfaces are model systems for the study of the electronic properties of silicon surfaces. The perfection of these surfaces leads to very sharp features in the high resolution photoemission spectra. New theoretical approaches based on first principle calculations agree with our experimental results, which allows a better understanding of the origin of the surfaces states at the HlSi(111) surfaces. The chemical treatment of vicinal Si(111) surfaces leads to dihydride or monohydride stepped surfaces. The comparison between flat and stepped surfaces show that long range order defects do not induce any important broadening of the spectral features. However additional surface states in the valence band spectra of the dihydride terminated surfaces are observed which are probably due to a local deformation at the steps.