Detailed photoemission studies of the Tm/GaAs(110) interface give clear evidence for an abrupt change in Fermi-level position at a relatively high Tm coverage (≃2.6 Å) by 0.22 eV towards the value expected from current-voltage measurements. This observation together with the strongly increasing density of states at the Fermi level around this coverage indicates that the Schottky barrier is not established until the overlayer assumes metallic character. The results are interpreted within the concept of metal-induced gap states defining the final Fermi-level position in Schottky barriers.

• Received 17 November 1986

DOI:https://doi.org/10.1103/PhysRevLett.60.436