Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

R. CUERNO; L.M. GASSA,; M.E. VELA; S. N. SANTALLA; S.B. RIBOTTA; R.C. SALVAREZZA; P.A. ORRILLO; L. VAZQUEZ; F. J. MOMPEAN

Scientific Reports

Nature Publishing Group

Lugar: London; Año: 2017 vol. 7 p. 1 - 12

We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. To this end, we have compared the kinetic roughening properties of NiW films with those of Ni films electrodeposited under the same conditions, as assessedby Atomic Force Microscopy. Both systems are super-rough at short times, while their long-time behavior differs: while it is dominated by a cauliflower-like morphology for Ni, for NiW films it is controlled by a nodular surface morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-Parisi-Zhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case,namely, mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW).Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditionsin which surface kinetics has been hindered due to a complex reaction mechanism at the interface. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.