The structure and crystal growth of nickel electrodeposits from a sulphamate bath on polished polycrystalline copper, in relation to thickness, rate of deposition, temperature and stirring

Abstract

Grazing-incidence electron diffraction shows the structure and growth of face-centred cubic (fcc) Ni electrodeposits from a sulphamate bath on polished polycrystalline Cu, at 50 and 20°C, both with and without stirring, at current density (cd) i up to 600 mA cm−2 at 50°C, and thickness H up to 60 000 Å or more.Seven isostructural regions of i and H are distinguished, with boundaries approximately of the form H(i-i0)=constant. The effects of bath temperature and of stirring are shown in detail. Ni(OH)2 is co-deposited at cd where the current efficiency falls appreciably below 100%.In the main lateral-growth region the Ni crystals soon develop cube faces (thus layerwise growth) and hence preferred {100} orientation develops (in part also {111} at low i and H). At high cd, {110} and/or {210} outward-growth orientation is developed. The dependence of the spread of orientation about the mean, on i, H, stirring, bath temperature and type of orientation, is shown. It is compatible with these crystal growth and orientation processes and with the cations being incident practically normal to the surface elements of the `rough' deposit.

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

“…All of them have been discussed in detail previously. 6 The pyramidtype Cu deposits were observed on (100) Cu and (111) Cu single-crystal substrates at low current densities. The side faces of the pyramids did not correspond to the low-index crystallographic planes but originated from the stacking of the pyramidal base planes presumably as a result of the spiral growth around threading screw dislocations.…”

“…As displayed in Fig. 7b, new grains of various orientations had nucleated on top of the (133)[32-3] epilayer and the (131) [3][4][5][6][7][8][9][10] grains on grain 2 upon subsequent deposition. Some of the grains among them had <100>∼//ND orientations and could, therefore, grow rapidly into columnar shapes.…”

“…In the case of Ni electrodeposition, however, the epitaxial films, no matter their orientations, have been reported to be thin when compared to the entire deposit. 5,6 The transition from epitaxial layers to textured columnar or fibrous grains during electrodeposition has not been explained well in the literature, although independent observations of epitaxial growth of Ni on single-crystal substrates and textural/microstructural investigation of Ni deposits on polycrystalline or amorphous substrates have been reported. [6][7][8][9][10] The electroepitaxy of Ni on single-crystal copper substrates has been studied extensively.…”

“…5,6 The transition from epitaxial layers to textured columnar or fibrous grains during electrodeposition has not been explained well in the literature, although independent observations of epitaxial growth of Ni on single-crystal substrates and textural/microstructural investigation of Ni deposits on polycrystalline or amorphous substrates have been reported. [6][7][8][9][10] The electroepitaxy of Ni on single-crystal copper substrates has been studied extensively. The effects of the deposition parameters including the current density (or overpotential), the composition/pH/temperature of the electrolyte, and the substrate orientation on the surface morphology and microstructure of the deposits have been reported.…”

“…3,10 Deposition on the (111) Cu substrate has been characterized as occuring through a pyramidal growth mode that results in a rough deposit surface. 3,7,8 Nevertheless, Verma and Wilman 6 reported that the Ni deposits formed on polycrystalline Cu in a sulfamate bath were nearly randomly oriented crystals, rather than epilayers. The limited spatial resolution of their reflective high energy diffraction technique might have failed to monitor the epitaxial growth on individual grains.…”