Composition and structure of the Co-Al interface for thin Co films deposited on Al(001) and Al(110) surfaces at room temperature

High-energy ion backscattering and channeling, combined with X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) were used to characterize the interface thickness and composition Tor thin Co films deposited on Al(001) and Al(110) surfaces at room temperature. For the Al(001) surface. measurements of the backscattered ion yields from Al and Co show that substrate Al atoms are continuously displaced for Co coverages up to 3 ML (monolayer, ML), at which point Co metal begins to cover the mixed interface. Based on XPS intensity analysis, we conclude that a CoAl-like phase forms at the interface. A very diffuse LEED pattern with high background was observed after a deposition of 7.6 ML of Co. For the Al(110) surface, intermixing of Co and Al atoms was observed up to 5 ML of Co deposition, where Co metal begins to cover the interface. No LEED pattern was observed for any Co coverage exceeding 0.2 ML on the Al(110) surface. The interface thickness is about 10 A for both surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.