Abrupt interfaces without substrate disruption are formed when metallic Co clusters are brought into contact with clean GaAs(110). Unique Fermi-level pinning positions 0.32 and 0.96 eV below the conduction band are nearly independent of surface coverage and appear to be related to states of the unrelaxed surface. No evidence is found for metal-induced midgap states or conventional defects. Co atom deposition induces substrate disruption at 60 and 300 K, with As surface segregation inhibited at 60 K. The temperature-dependent Schottky-barrier evolution for n-GaAs shows that pinning is not controlled simply by levels related to surface disruption.

• Received 13 October 1988

DOI:https://doi.org/10.1103/PhysRevLett.62.1568