Direction-tunable nanotwins in copper nanowires by laser-assisted electrochemical deposition.

Nanotwins can improve mechanical strength and maintain high electrical conductivity in metallic nanowires. We demonstrated a method of pulsed-laser-assisted electrodeposition, which could form dense nanotwins with tunable directions in copper nanowires of uniform sizes. Transmission electron microscopy characterization showed with a growth potential of -0:2 V, nanotwins tend to align along the longitudinal direction of the nanowires, whereas at a larger potential of -0:8 V, nanotwins of {111}g/<112> type perpendicular to the longitudinal direction of the wire were formed. The two types of nanotwins were investigated by comparing the microstructures under different electrochemical conditions and laser irradiation energies. Two different mechanisms are proposed—annealing twins and growth twins.