Disorder-controlled quantum-to-classical transport crossover in TiN thin films on mica

Abstract

TiN thin films were deposited on muscovite mica substrates over a wide range of growth temperatures (25–400 °C) to investigate the influence of substrate-mediated microstructure on electronic transport. X-ray diffraction confirms crystalline TiN formation across the growth series, while scanning electron microscopy reveals a pronounced cellular grain-boundary network in films grown at ≤300 °C that is substantially suppressed at 400 °C. Temperature-dependent resistivity measurements performed between 4.5 and 300 K show a systematic decrease in room-temperature resistivity from 249.6 to 57.8 μΩ cm with increasing deposition temperature. Films grown at low and intermediate temperatures exhibit a persistent negative temperature coefficient of resistivity up to 300 K, whereas films deposited at 400 °C approach conventional metallic behavior. Analysis of the resistivity using models incorporating quantum correction terms is consistent with an enhanced contribution from disorder-related interaction effects in the lower-temperature-grown films. Seebeck measurements at 300 K yield Fermi energies and carrier densities characteristic of metallic conduction across all samples. The estimated density of states at the Fermi level varies modestly with deposition temperature, while the diffusion constant increases substantially, supporting an interpretation in which the transport evolution is primarily associated with changes in disorder strength. These combined trends are consistent with a growth-temperature-controlled crossover from quantum-influenced to increasingly classical metallic transport in TiN thin films on mica substrates.