First-principles Quantum Molecular Dynamics Study of Ti_xZr_1-xN(111)/SiN_y Heterostructures

Abstract

Heterostructures with 1 monolayer of Si₃N₄-like Si₂N₃ interfacial layer between five monolayers thick B1-Ti_xZr_1-xN(111), x 1.0, 0.6, 0.4 and 0.0, slabs were investigated by means of first-principles quantum molecular dynamics and structure optimization procedure using the Quantum ESPRESSO code. Slabs consisting of stoichiometric TiN and ZrN and random, as well as segregated B1-Ti_xZr_1-xN(111) solutions were considered. The calculations of the B1-Ti_xZr_1-xN solid solutions as well as of the heterostructures showed that the pseudo-binary TiN-ZrN system exhibits a miscibility gap. The segregated heterostructures in which the Zr atoms surround the Si_yNz interface were found to be most stable. For the Zr-rich heterostructures, the total energy of the random solid solution was lower compared to that of the segregated one, whereas for the Ti-rich heterostructures the opposite tendency was observed.