Effects of epitaxial strain on electronic and vibrational structure of δ-NbN from first-principles

Niobium Nitride is a material often used for its application in quantum technologies such as superconducting nanowire single-photon detectors and Josephson junctions because of its high critical temperature (17K) and high superconducting gap. Recent developments on epitaxial integration of transition metal nitride superconductors with nitride semiconductors opened possibilities to control electronic, vibrational, and superconducting properties. Using first-principles calculations, we study the trends in the electronic band structure and phonon spectra of NbN under epitaxial biaxial strain along two principal growth directions [100] and [111], with the goal of achieving tailored superconducting properties.