Preparation and characterization of Cu(111)-Ni and Cu(110)-Ni surface alloys

Abstract

The interaction of Ni(CO)4/CO gas mixtures with Cu(111) and Cu(110) single crystal surfaces has been studied with ellipsometry. Auger electron spectroscopy, LEED and argon ion depth profiling. At room temperature Ni atoms with some CO ligands remain at the surface. The amount of Ni that can be deposited is less than one monolayer. The alloy surface is able to bind CO. After exposures above 220°C, the initially deposited amount of Ni resides below the first layer of Cu atoms. The amount of Ni that can be deposited is essentially unlimited. The alloy surfaces show no contamination of C or O at the surface or in deeper layers. The Ni concentration profile below the surface is bell shaped and is metastable up to 400–450°C. The ellipsometric data can be understood if one assumes that a significant fraction of voids are present in the Cu-Ni layer.