摘要： Transition metal nitrides, like titanium nitride (TiN), are promising alternative plasmonic materials. Here we demonstrate a low temperature plasma‐enhanced atomic layer deposition (PE‐ALD) of non‐stoichiometric TiN0.71 on lattice‐matched and ‐mismatched substrates. The TiN was found to be optically metallic for both thick (42 nm) and thin (11 nm) films on MgO and Si <100> substrates, with visible light plasmon resonances in the range of 550–650 nm. We also demonstrate that a hydrogen plasma post‐deposition treatment improves the metallic quality of the ultrathin films on both substrates, increasing the ε1 slope by 1.3 times on MgO and by 2 times on Si (100), to be similar to that of thicker, more metallic films. In addition, this post‐deposition was found to tune the plasmonic properties of the films, resulting in a blue‐shift in the plasmon resonance of 44 nm on a silicon substrate and 59 nm on MgO.