Fermi-level pinning and growth characteristics of Au on InP(111)

Atomically clean phosphorus-enriched InP(111) surfaces have been produced by argon sputtering and subsequent annealing in a phosphorus ambient. Pinning of the surface Fermi level at a position 1.10 eV above the valence band maximum has been observed on clean, well-annealed InP(111). In addition, a range of surface Fermi levels from 0.70 to 1.10 eV above the valence band maximum has been observed for various InP(111) surfaces as a function of annealing temperature and degree of stoichiometry. For a well-annealed InP(111) surface, the Fermi level position after gold deposition appears to saturate at a position 0.70 eV above the valence band maximum. We interpret these results in terms of multiple defect levels in the bandgap. Observations of In4d and Au4f photoemession peaks demonstrate both the dissociation of InP and intermixing between gold and the substrate. Photoemission of adsorbed xenon further indicates that intermixing occurs without formation of Au clusters.