• Acharya, R.
• Couet, S.
• Vadiraj, A. M.
• Wan, D.
• Canvel, Y.
• Piao, X.
• Mongillo, M.
• Swerts, J.
• Lozano, D. P.
• Damme, J. Van
• Greve, K. De
• Mohiyaddin, F. A.
• Jussot, J.
• Gowda, P. P.
• Verjauw, J.
• Potočnik, A.
• Ivanov, Ts.
• Govoreanu, B.
• Pacco, A.
• Raes, B.
• Vondel, J. Van De
• Radu, I. P.

Abstract

The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric losses at different surfaces and interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. However, without the use of a seed layer, this tantalum phase has so far only been realised on sapphire substrates, which is incompatible with advanced processing in industry-scale fabrication facilities. Here, we demonstrate the fabrication of high-quality factor α-tantalum resonators directly on silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. By comparing experiments with simulated resonator loss, we demonstrate that two-level-system loss is dominated by surface oxide contributions and not the substrate-metal interface. Our study paves the way to large scale manufacturing of low-loss superconducting circuits and to materials-driven advancements in superconducting circuit performance.

Topics

• Deposition
• impedance spectroscopy
• surface
• phase
• experiment
• Silicon
• tantalum