In-situ growth of epitaxial Au-Sn films on Au(111): An XPS and LEED study

We establish a method of growing epitaxial Au-Sn compound films in ultra-high vacuum by in-situ deposition of Sn on Au(111) and subsequent heat treatment by post-annealing. The composition, electronic structure, and the surface ordering of these films have been studied using x-ray photoemission spectroscopy and low energy electron diffraction (LEED). The AuSn film grows at room temperature, whereas Au-rich films with compositions ranging from Au3Sn to Au6Sn are obtained post-annealing in the temperature range of 493 to 593 K. The thickness of the film is 11 nm for AuSn, which increases to 26 nm for Au5Sn. Sharp diffraction spots in the LEED pattern are observed, establishing that the post-annealed films are epitaxial.