Temperature Invariant, Nearly Zero Temperature Coefficient of Resistivity in Si-Doped Titanium Nitrides

Materials with near-zero temperature coefficient of resistivity (nz-TCR) are critical for precision electronics operating across wide temperature ranges, yet achieving ultra-stable resistivity remains a challenge. Here, a mixed nitride Ti─Si─N thin film system is demonstrated exhibiting exceptional nz-TCR stability (0.05 ppm K^-1) from 80 to 420 K, realized through atomic-level control of electron scattering mechanisms. By tuning Si content in TiN (2-4 at%), a TCR transition from metallic (positive) to insulating (negative) behavior is induced, with optimal stability at Ti_0.98Si_0.02N. Atomic layer deposition enables precise synthesis, while structural, electronic, and thermal characterization, supported by density functional theory-based calculations, reveal that nz-TCR arises from a control of elastic mean free path and average diffusion length of electrons. The elastic mean free path (0.712 nm) approaches the lattice parameter (0.455 nm), and the average diffusion length (5.5 nm) aligns with the size of Si decorated grains (5.66 nm), thus leading to temperature invariant electronic transport. This work provides a generalizable design principle for ultra-stable nz-TCR resistors using composition control and grain-boundary engineering.