Growth and surface alloying of Al on Au(111) at room temperature

The initial stages of epitaxial growth of Al on Au(111) at room temperature have been investigated by scanning tunneling microscopy. In the submonolayer regime, large dendritic islands form. Their size distribution is found to be bimodal with the coexistence of a large area density of small and few large islands. The nucleation of second layer islands starts in advance of monolayer completion. Thicker films are rough. High-resolution data reveal that surface strain and intermixing of the two metals play a decisive role in the growth behavior: small quantities of adsorbed Al atoms strongly perturb the chevron reconstruction of clean Au(111) and a reconstruction pattern with hexagonal symmetry evolves for Al coverages exceeding approximate to 0.1 monolayers. This hexagonal domain wall phase consists of an intermixed Al-Au surface alloy layer with reduced atomic Al radii. (C) 1997 Elsevier Science B.V.