Multiparametric electrochemical characterisation of Te-Cu-Pb atomic three-layer structure deposition on polycrystalline gold

Successive underpotential deposition of Te-ad, Cu-ad and Pb-ad adlayers in the potentiodynamic mode was used for Te-ad/Cu-ad/Pb-ad atomic three-layer structure assembling on polycrystalline Au support. Layer-by-layer deposition was characterised in each of the stages with potentiodynamic electrochemical impedance spectroscopy (PDEIS) by variations, with the electrode potential E, of double layer pseudocapacitance Q(dl), charge transfer resistance R-ct and Warburg coefficient A of diffusion impedance. Q(dl)(E) has shown a strong decrease in the cathodic scan during Te atomic layer deposition on Au, a sharp peak in the subsequent Cu-ad deposition on Au/Te-ad and an increase in Pb-ad deposition on Au/Te-ad/Cu-ad. The inverses of charge transfer resistance and Warburg coefficient have shown characteristic maxima in R-et(-1) (E) and A(-1)(E) dependencies in all the three stages of Te-ad/Cu-ad/Pb-ad three-layer assembling. The characteristic features in the dependences on the potential of the ac response parameters compensated for insufficient self-descriptiveness of the do part of the nonstationary interface response in the layer-by-layer deposition. High information density of PDEIS spectra provides better control of electrochemical processes on nonstationary interfaces and this new opportunity can enable wider use of electrochemical approaches for thin-layer structures preparation. (C) 2006 Elsevier B.V. All rights reserved.