Surface roughness of electrodeposited Co-Ni-Cu/Cu multilayers

Co-Ni-Cu/Cu multilayer films form one of the most promising electrodeposited systems for giant magnetoresistance applications. We have studied the surface roughness of Co-Ni-Cu/Cu multilayers with different total thickness and different layer thicknesses systematically by ex situ atomic force microscopy. Films for which the Cu deposition potential was -0.4 or -0.5 V relative to a saturated calomel reference electrode were significantly smoother than films for which the deposition potential was -0.2 V when the total film thickness was less than about 300 nm. For films grown on deliberately roughened substrates, a critical thickness at which the roughness changed from being substrate-dominated to being growth-dominated was identified.