Evolution of Surface Roughness in Electrodeposited Co–Ni–P and Co–Ni Films

Dynamic scaling analysis was applied to the investigation of the roughening kinetics of Co–Ni and Co–Ni–P films electrodeposited from acidic (pH 3) chloride solutions. Co–Ni films exhibit uninhibited growth with the formation of well-defined crystal facets, while Co–Ni–P films exhibit a granular microstructure with a much smaller apparent grain size. Correspondingly, the rate at which Co–Ni–P films roughen is much slower than that of the Co–Ni films. This is ascribed to autocatalytic processes during Co–Ni–P deposition occurring in parallel with electrochemical processes, inducing growth inhibition due to the ongoing nucleation, incorporation of phosphorus, and enhanced hydrogen evolution. The slow roughening of Co–Ni–P films is advantageous for microfabrication processes involving the formation of thick magnetic films and microstructures.