Copper Better than Silver: Electrical Resistivity of the Grain-Free Single-Crystal Copper Wire

Using a single-crystal wire fabricated through the crystal growth process, the contribution of grain boundaries (GBs) to electrical resistivity was investigated in copper. We developed a novel wire fabrication process that preserved the grain-free structure of single-crystal copper (SCC) grown by the Czochralski method. The resistivity of grain-free SCC showed a reduction of 9% compared to the international annealed copper standard (IACS) resistivity, with the resulting value smaller than that of silver. We also found that the GBs strongly influenced the resistivity above 70 K, but hardly contributed below 70 K, unlike the impurities. Insights into the GB effects could contribute to our understanding of conducting phenomena and the development of nanoscale analytical models.