We assess the viability of topological semimetals for application in advanced interconnect technology, where conductor size is on the order of a few nanometers and grain boundaries are expected to be prevalent. We investigate the electron transport properties and grain-boundary scattering in thin films of the topological semimetals $\mathrm{Co}\mathrm{Si}$ and $\mathrm{Co}\mathrm{Ge}$ using first-principles calculations combined with the nonequilibrium Green’s function (NEGF) technique. Unlike conventional interconnect metals such as $\mathrm{Cu}$ and $\mathrm{Al}$, we find that $\mathrm{Co}\mathrm{Si}$ and $\mathrm{Co}\mathrm{Ge}$ conduct primarily through topologically protected surface states in thin-film structures even in the presence of grain boundaries. The area-normalized resistance decreases with decreasing film thickness for $\mathrm{Co}\mathrm{Si}$ and $\mathrm{Co}\mathrm{Ge}$ thin films both with and without grain boundaries; a trend opposite to that of the conventional metals $\mathrm{Cu}$ and $\mathrm{Al}$. The surface-dominated transport mechanisms in thin films of topological semimetals with grain boundaries does not follow the classic resistivity size effect, and suggests that these materials may be promising candidates for applications as nanointerconnects where high electrical resistivity acts as a major bottleneck limiting semiconductor device performance.

• Received 7 September 2021
• Revised 4 April 2022
• Accepted 15 August 2022

DOI:https://doi.org/10.1103/PhysRevApplied.18.034053