SURFACE-STRESS PHENOMENA AT THE START OF EPITAXIAL ELECTRODEPOSITION OF NICKEL

In studies to determine the internal stresses during epitaxial nickel electrocrystallization, bending of thin copper substrates was observed to occur upon application of the deposition potential but before any deposit had formed. This phenomenon was attributed to the changes in the surface tension upon application of the deposition potential. The sign of the internal stress in the discrete crystallites, which constitute the initial electrocrystallization, could only be determined in the absence of the otherwise overshadowing stress contribution due to the lattice mismatch between substrate and deposit. Deposition was interrupted, so that upon resumption of deposition now on a nickel substrate the mismatch-stress contribution was absent. Then it was found when a new layer of crystallites formed, that they were under a compressive stress. Such new crystallite layers formed when the nickel surface became passivated during a prolonged interruption or a polarity reversal. Sulfur from saccharin addition to the electrolyte prevented the passivation. © 1979, The Electrochemical Society, Inc. All rights reserved.