Epitaxial growth and physical properties of ternary nitride thin films by polymer-assisted deposition

Epitaxial layered ternary metal-nitride FeMoN₂, (Fe_0.33Mo_0.67)MoN₂, CoMoN₂, and FeWN₂ thin films have been grown on c-plane sapphire substrates by polymer-assisted deposition. The ABN₂ layer sits on top of the oxygen sublattices of the substrate with three possible matching configurations due to the significantly reduced lattice mismatch. The doping composition and elements affect not only the out-of-plane lattice parameters but also the temperature-dependent electrical properties. These films have resistivity in the range of 0.1-1 mΩ·cm, showing tunable metallic or semiconducting behaviors by adjusting the composition. A modified parallel connection channel model has been used to analyze the grain boundary and Coulomb blockade effect on the electrical properties. The growth of the high crystallinity layered epitaxial thin films provides an avenue to study the composition-structure-property relationship in ABN₂ materials through A and B-site substitution.