Sublayers thickness correction for electrodeposited Cu/Ni multilayer nanocomposites
Adam Tokarz, Zygmunt Nitkiewicz Politechnika Częstochowska, Instytut Inżynierii Materiałowej, al. Armii Krajowej 19, 42-200 Częstochowa
Quarterly No. 3, 2006 pages 33-38
DOI:
keywords: nanocomposite, coating, multilayer, electrodeposition
abstract Electrochemical growth of layered nanocomposites of Cu/Ni on (100) Si and polycrystalline Cu substrates has been investigated. The multilayers were prepared by a single electrolyte technique in a conventional three-electrode electrochemical cell from an electrolyte containing: 1.5 M nickel sulfamate Ni(SO3NH2)2; 0.01 M copper sulphate CuSO4 and 0,5 M boric acid H3BO3. The pH was maintained at 3.5. The deposition process was controlled by potentionstat AMEL 2053 with our own software (Fig. 1). Polarisation experiments for both substrates were made to find suitable deposition potentials of Cu and Ni sublayers (Fig. 2). The analysis of the electric current and charge transient (recorded during pulse potential wave) (Fig. 3) combined with the XRD measurements (Fig. 4) show a discrepancy in the nominal and actual thickness of Cu and Ni sublayers. The nominal thickness of each Ni sublayer has to be increased because of two causes: ● in initial stage when the Ni potential is applied to the electrode and a quick period Cu deposition takes place (this reaction is preferred because cooper is more noble than nickel), ● at the beginning of each Cu layer deposition the more noble Cu atoms replaced the previously deposited Ni atoms. A graphical model of the changes in the nominal and real sublalyer thickness was presented (Fig. 5). In our case the difference between the nominal and actual thicknesses amounts 0.5 nm. After taking this model into consideration, several series of Cu/Ni multilayer with the demand thickness of Cu and Ni sublayer were grown (Fig. 6). X-ray diffraction studies have revealed the periodical structure of the electrodeposited multilayers and allowed determining Λ value after precise establishing diffraction lines S±i and ML.