Surface Loss Characterization and Comparison in Aluminum, Niobium, and Titanium Nitride Superconducting Resonators*

Uniquely characterizing loss from two-level systems (TLS) at metal-substrate, metal-air, and substrate-air interfaces and in a dielectric substrate is challenging due to the nearly proportional scaling of the dielectric participations in response to changes in geometry and anisotropic trench depth. We developed a technique utilizing isotropic etching to assign a specific loss tangent to each dielectric, and use that to determine the dominant dielectric losses for a specific fabrication process, enabling targeted geometry and process changes to maximize performance. In this talk, we characterize the loss from high quality factor resonators (Qi>1M) for aluminum, titanium nitride, and niobium, and demonstrate the technique’s application by targeting specific defect layers to alter the dielectric losses specifically from these defect layers.