Self-assembly from the branch pattern to parallel wire array in electrodeposition

We report a self-organized copper electrodeposition without imposed templates and induced additives. The deposit morphology on the silicon substrate varies from a branch to a parallel pattern by changing the applied voltage. We suggest that there are two essential factors for the formation of such kind of copper wire arrays. One is a proper electric potential distribution near the tip of the copper wire which dictates the direction of the solute transport. The other one is that the cathode overpotential and the equilibrium potential of reaction should remain unchanged at the growing interface.