Annealing reduces Si\(_3\)N\(_4\) microwave-frequency dielectric loss in superconducting resonators

• Published in: arXiv.org 2024-05
• Main Authors: Mittal, Sarang, Kazemi Adachi, Frattini, Nicholas E, Urmey, Maxwell D, Sheng-Xiang, Lin, Emser, Alec L, Metzger, Cyril, Talamo, Luca, Dickson, Sarah, Carlson, David, Papp, Scott B, Regal, Cindy A, Lehnert, Konrad W
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Annealing; Damping; Dielectric loss; High temperature; High temperature effects; Infrared absorption; Resonators; Silicon nitride; Superconductivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2312.13504

The dielectric loss of silicon nitride (Si\(_3\)N\(_4\)) limits the performance of microwave-frequency devices that rely on this material for sensing, signal processing, and quantum communication. Using superconducting resonant circuits, we measure the cryogenic loss tangent of either as-deposited or high-temperature annealed stoichiometric Si\(_3\)N\(_4\) as a function of drive strength and temperature. The internal loss behavior of the electrical resonators is largely consistent with the standard tunneling model of two-level systems (TLS), including damping caused by resonant energy exchange with TLS and by the relaxation of non-resonant TLS. We further supplement the TLS model with a self-heating effect to explain an increase in the loss observed in as-deposited films at large drive powers. Critically, we demonstrate that annealing remedies this anomalous power-induced loss, reduces the relaxation-type damping by more than two orders of magnitude, and reduces the resonant-type damping by a factor of three. Employing infrared absorption spectroscopy, we find that annealing reduces the concentration of hydrogen in the Si\(_3\)N\(_4\), suggesting that hydrogen impurities cause substantial dissipation.