Conduction in ultrathin ruthenium electrodes prepared by atomic layer deposition

Ultrathin ruthenium layers, produced by atomic layer deposition for use in nanostructured devices, show a dramatic decrease in conductivity (~ 5 ×) when scaled down in thickness, from ~ 38 × 103 S cm− 1 for 24 nm films to ~ 8 × 103 S cm− 1 for 5 nm films. This suggests a significant change in the dominant mechanisms for electron scattering, as expected from Mayadas–Schatzkes theory for thin films, where surface/interface and grain boundary scattering dominate over electron–phonon scattering. The temperature coefficient of resistivity also decreases substantially, ~ 9 ×, with decreasing film thickness, consistent with a stronger role for electron scattering at boundaries as compared to electron–phonon scattering.

► Ru films fabricated with ALD are of interest in memory and energy device applications. ► Future devices will require films significantly thinner than films studied in the literature. ► As Ru films approach the few nanometer range a drastic decrease in conductivity is seen. ► Resulting in significant consequences for device performance.