AN INVESTIGATION OF THE ORDERED AU/CU(111) SURFACE - LEED, ARAES AND ARUPS RESULTS

A (2 × 1)/(1 × 2) ordered structure prepared by vapor deposition of Au onto Cu(111) and subsequent heating has been characterized by means of LEED, ARAES and ARUPS. ARAES analysis shows a Au content of 55% and 50% in the first two layers, respectively, using pure Au and Cu for calibration. This suggests that a mixed (2 × 1) and (1 × 2) structure with co-planar Au and Cu atoms exists on the top layer corresponding to CuAu(111) rather than Cu3Au(111). It is also inferred from the ARAES analysis that the top layer is rippled with the Au atoms about 0.4 Å higher than the Cu atoms. Au-induced features at about 6.5 and 5.9 eV below the Fermi level are observed from the ARUPS using He I, and their dispersion along the [11̄0] and the [112̄] directions is also determined. After evaporating two or more layers of Au atoms on Cu(111), as indicated by measurement of ARAES, LEED shows epitaxial hexagonal Au layers with a nearest-neighbor spacing of pure Au. © 1990.