Composition and structure of the Co–Al interface for thin Co films deposited on Al(0 0 1) and Al(1 1 0) surfaces at room temperature

Abstract

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 for thin Co films deposited on Al(0 0 1) and Al(1 1 0) surfaces at room temperature. For the Al(0 0 1) 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(1 1 0) 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(1 1 0) surface. The interface thickness is about 10 Å for both surfaces.