Probing Microstructure, Superconducting Properties and Disorder in NbN Thin Films Using Kinetic Inductance Devices

Superconducting transition metal nitrides such as NbN and TiN are promising for next-generation quantum technologies due to their high critical temperature (Tc), negligible native oxide formation, kinetic inductance tunability and compatibility with semiconductor fabrication processes. Achieving optimal performance requires precise control of thin-film growth to tailor crystallinity, stoichiometry, and defect density. Here, we present a systematic study of NbN films grown by DC reactive sputtering at Berkeley Lab’s Molecular Foundry, combining structural, chemical, and electrical characterization to directly correlate microstructure and composition with superconducting properties. By varying substrate choice, deposition temperature, and nitrogen partial pressure, we probe their influence on crystallinity, composition and high-Tc phase formation. Kinetic inductance resonators further reveal the impact of disorder on microwave performance through power- and temperature-dependent quality factor measurements. This work establishes a robust framework for the design, synthesis, and optimization of high-quality superconducting nitride films for scalable quantum circuits and devices.