Wafer-Scale Epitaxy of Flexible Nitride Films with Superior Plasmonic and Superconducting Performance

TL;DR

This paper demonstrates the wafer-scale epitaxial growth of high-quality flexible TiN films on F-mica substrates, exhibiting superior plasmonic and superconducting properties, with superconductivity tunable by bending-induced strain.

Contribution

It reports the first high-quality wafer-scale epitaxy of flexible transition-metal nitride films with tunable superconductivity and superior plasmonic performance.

Findings

High-quality 2-inch TiN films on flexible F-mica substrates.

Superb plasmonic and superconducting performance due to high crystallinity.

Superconductivity can be enhanced by in-plane tensile strain through bending.

Abstract

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.