Strain- and temperature effects on structure-property relationships in nanocrystalline tungsten thin films

Nanocrystalline tungsten (nc-W) thin films are promising for nanoelectronic applications owing to their high thermal stability, mechanical robustness, and tunable electronic transport properties. In this work, the electrical resistivity, temperature coefficient of resistance (TCR), and strain coefficient (SC), correlating transport behaviour with microstructural evolution under thermal and mechanical loading was systematically investigated. Electrical conduction is found to be governed primarily by electron scattering at grain boundaries and film surfaces. The effective electron mean free path, limited by grain boundaries, is ~ 8.0 nm, while the grain-boundary reflection coefficient is R ≈ 0.49 ± 0.02, indicating intermediate interfacial scattering strength. Under quasi-elastic longitudinal strains of 1-2%, the films exhibit enhanced strain sensitivity with SC ≈ 4.7, whereas the TCR remains stable at ~ 1.3 × 10⁻³ K⁻¹ over the 300-800 K range, demonstrating robust thermal stability of the transport response. These findings indicate that grain-boundary scattering dominates charge transport and can be modulated through strain- and temperature-induced microstructural evolution, suggesting that grain boundaries act as structurally tunable interfaces governing macroscopic electronic behaviour in nanocrystalline metals.