Electronic surface states at steps in Si(111) 2×1

Step-related surface states in Si(111)2 × 1 are investigated by optical reflectivity. Transitions involving these states occur at 0.35 eV, while terrace-states give rise to the well known peak at 0.45 eV. The experimental data point out that occupied surface states related to steps have a slightly higher energy than terrace-states and therefore they should play a role in the Fermi level pinning.