Epitaxial Growth and Microstructural Evolution of Nickel Electrodeposited on a Polycrystalline Copper Substrate

Abstract

An ex-situ method has been used to study the anisotropy of the epitaxial growth of Ni electrodeposited onto a polycrystalline Cu substrate from a sulfamate solution. Nickel films, approximately 1 μm thick, were deposited galvanostatically onto the polished substrates at current densities ranging from 2 to 250 mA/cm 2 . The orientations of the Ni deposits and substrates were analyzed through EBSD to reveal the orientation relationship between each deposit/substrate pair. EBSD analysis was also performed for thick deposits to clarify the growth behavior and microstructural evolution on grains having different orientations. At 2 mA/cm 2 , epitaxial growth to thickness of up to 1 μm was allowed solely on grains having the orientation <100>//ND (normal direction). In contrast, the Ni deposits grew epitaxially on all grains, no matter the orientation, when the current density was in the range from 10 to 100 mA/cm 2 . The surfaces of the non-{100} oriented epilayers gradually roughened, however, upon increasing their thickness, and the epitaxial growth was eventually prohibited by the formation of a polycrystalline transition layer through a twin-mediated nucleation process. A microstructural evolution model is proposed herein based on the inhibition of the electrolyte and the anisotropic growth of the crystal planes during electrodeposition.

High density of genuine growth twins in electrodeposited aluminum

“…This seems to be similar to the case of pulse Cu deposits, where twins and the presence of hydrogen were observed ( 35 ). In the case of electrodeposited Ni, the influence of hydrogen is expected since Ni is a catalyst for hydrogen evolution, which could be correlated to twin-related grains grown epitaxially on Cu substrate ( 36 ). In our case, direct evaluation of this hydrogen effect is difficult as introduction of protons as a source for hydrogen would inevitably result in further water contamination.…”

Recent Progress on Two-Dimensional Materials

“…For thin film grown on a substrate, the strong chemical bonding ensures an epitaxial relationship between the crystalline lattice of the overlayer material and that of the substrate (Fig. 65a) 1626,1627 . So, when the growth of 2D materials covering a polycrystalline substrate grain boundary, the 2D thin film have to change its crystallographic orientation to match its lattice orientation with the substrate 1626 .…”

Effect of Electrolyte Concentration on Epitaxial Growth of ZnO on Cu Substrates through Electrochemical Deposition

“…The electropolishing parameters and surface morphology and roughness of Cu grains in various orientations have been reported elsewhere. 20 Two series of electrodeposition experiments were conducted. First, the zinc nitrate concentration in the electrolyte, containing 0.4 M potassium nitrate, was varied from 0.0025 to 0.08 M. Second, the potassium nitrate concentration was varied from 0.1 to 2.0 M for a fixed zinc nitrate concentration of 0.02 M. Table I displays the sample designations and corresponding electrolyte concentrations.…”