Extremely anisotropic single-crystal growth in nanotwinned copper

Abstract

By electroplating the unidirectionally <111>-oriented nanotwinned and fine-grained Cu on a Si wafer surface and followed by annealing at 400–500 °C up to an hour, we grow a number of extremely large <100>-oriented single crystals of Cu of sizes from 200 to 400 μm, as illustrated by the left figure. By patterning the nanotwinned Cu film (middle figure), we grow an array of <100>-oriented single crystals of Cu of sizes from 25 to 100 μm on Si after the annealing, as shown in the right figure.