Metal/Metal Multilayers Electrodeposited from Ethaline

Abstract

Many researchers have studied metal/metal multilayer films electrodeposited from a single electrolyte under potentiostatic or galvanostatic control. When the electrolyte contains a high concentration of a less noble metal and a low concentration of a more noble one it is possible to alternate between depositing the latter in pure form and an alloy whose composition is dominated by the less noble component through switching either the deposition potential or current density. Most work in this field has used aqueous electrolytes, but in some situations working with alternative solvents could offer advantages. Here we present results for Ni-Cu/Cu multilayers electrodeposited from an ethaline (1:2 choline chloride : ethylene glycol) electrolyte containing 0.06 M Cu and 0.6 M Ni. The deposition potential was alternated between -0.6 V vs. Ag/AgCl at which Cu was deposited and -1.1 V at which a Ni-Cu alloy was expected. Specular films consisting of multiple repeats with nominal thicknesses down to 10 nm Cu/ 10 nm Ni-Cu were obtained.