Runaway growth in two-dimensional electrodeposition

We have investigated electrochemical deposition of copper along a very thin gold edge. Exploration of the transition between compact and branched morphologies reveals a faceted morphology, at very low current densities, which is composed of a pentagonal arrangement of twinned crystals. For higher current densities, repeated nucleation gives a tip-splitting regime. A transition between tip-splitting and side-branching morphology is obtained by inducing anisotropy on the substrate, in the form of microscopic teflon furrows. The growth speed of the different morphologies is very different.