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QI: Fachverband Quanteninformation
QI 11: Implementations IV
QI 11.10: Vortrag
Mittwoch, 11. März 2026, 12:30–12:45, BEY/0245
TiN superconducting resonators: influence of sputter conditions on Qi(T) and TLS-based loss modeling — •Benedikt Schoof1, Moritz Singer1, Harsh Gupta1, Simon Lang2, and Marc Tornow1,2 — 1TUM CIT, 85748 Garching, Germany — 2EMFT, 80686 Munich, Germany
We investigate how reactive sputter conditions affect the internal quality factor as a function of temperature (Qi(T)) of TiN coplanar-waveguide resonators. TiN films were grown on high-ohmic silicon (100) under varied substrate temperature (RT to 500 C), pressure (2 mbar to 18 mbar) and N2/Ar gas flow ratio (0.0 to 1.0). Electrical characterization yielded resistivity values in the range of 100 microOhm cm to 100 milliOhm cm and Tc values from 0.5 K to 5.1 K, which together with XPS, XRD and ToF-SIMS data were correlated with the Qi(T) data extracted from CPW resonators fabricated from these films. We find that films sputtered at elevated substrate temperature exhibit higher Qi (0.8e6) in the single-photon regime at 100 mK and are well described by a standard additive loss model with a single two-level-system (TLS) component. In contrast, room-temperature sputtered films require two distinct TLS contributions to reproduce the full Qi(T) dependence, indicating multiple dielectric defect populations or enhanced interfacial disorder introduced during low-temperature growth. Tc shows only a weak correlation with Qi, confirming that superconducting transition metrics alone do not capture the relevant microwave loss mechanisms. Our results provide quantitative guidance for optimizing TiN resonators for superconducting-qubit applications.
Keywords: Titaniumnitride; Superconducting; Qubit; Temperature; Two-Level-Systems