Structure and stability of transition metal nitride interfaces from first-principles: AlN/VN, AlN/TiN, and VN/TiN

We perform first-principle density-functional theory calculations using the full-potential linearized augmented plane wave method to investigate the formation, atomic and electronic structure, and stability of the metal-nitride interface systems, (1 0 0) AlN/TiN, AlN/VN, and VN/TiN in the rocksalt structure. We also determine the surface, interface, and strain energies, of the constituent materials, as well as the layer-dependent interaction energy between the adlayer surface and the interface. We find that this latter interaction, while typically not taken into account, plays an important role in terms of the formation energy for the initial stages of film growth. Using these energy quantities we calculate the film formation energy as a function of thicknesses, where we find that the growth of TiN on VN has the lowest formation energy, followed respectively by AlN on VN, and AlN on TiN. The formation energy of the latter two systems is notably higher due to the significantly higher energy of the metastable rocksalt phase of AlN compared to the stable wurtzite structure. From our calculations, together with experiment, we can predict the values of the interface energy of wurtzite-AlN on VN(1 0 0) and TiN(1 0 0).