  Transition-metal nitrides (e.g., TiN, ZrN, TaN) are incredible materials with
excellent complementary-metal-oxide-semiconductor compatibility and remarkable
performance in refractory plasmonics and superconducting quantum electronics.
Epitaxial growth of flexible transition-metal nitride films, especially at
wafer-scale, is fundamentally important for developing high-performance
flexible photonics and superconducting electronics, but the study is rare thus
far. This work reports the high-quality epitaxy of 2-inch titanium nitride
(TiN) films on flexible fluorophlogopite-mica (F-mica) substrates via reactive
magnetron sputtering. Combined measurements of spectroscopic ellipsometer and
electrical transport reveal the superior plasmonic and superconducting
performance of TiN/F-mica films owing to the high single crystallinity. More
interestingly, the superconductivity of these flexible TiN films can be
manipulated by the bending states, and enhanced superconducting critical
temperature TC is observed in convex TiN films with in-plane tensile strain.
Density-functional-theory calculations uncover that the strain can tune the
electron-phonon interaction strength and resultant superconductivity of TiN
films. This study provides a promising route towards integrating scalable
single-crystalline conductive transition-metal nitride films with flexible
electronics for high-performance plasmonics and superconducting electronics.
