Promoter-driven recrystallization affording highly textured ruthenium

The electrical properties of polycrystalline materials are governed by crystallite characteristics and spatial arrangement. We grew ruthenium polycrystals with a near-complete out-of-plane preferred orientation and predominantly low-energy grain boundaries on amorphous dielectric substrates, without relying on epitaxial growth or lattice-matched conditions. Whereas prior studies used high-density, high-quality polycrystalline materials derived from high-purity sources, we exploited trace carbon as a transient promoter at grain boundaries, revealing that it generated transient free volume during recrystallization and thus facilitated atomic migration, driving the dynamic vertical and horizontal orientation of grains. Our findings provide microscopic insights into the engineering of grain boundary kinetics through controlled trace element incorporation. The developed strategy is applicable to other polycrystalline materials, offering versatility for advanced material design and applications.