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arXiv · 2307.11667

Grain size in low loss superconducting Ta thin films on c-axis sapphire

Sarah Garcia Jones·Nicholas Materise·Ka Wun Leung·Brian D. Isakov·Xi Chen·Jiangchang Zheng·Andras Gyenis·Berthold Jaeck·Corey Rae H. McRae
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Abstract

In recent years, the implementation of thin-film Ta has led to improved coherence times in superconducting circuits. Efforts to further optimize this materials set have become a focus of the subfield of materials for superconducting quantum computing. It has been previously hypothesized that grain size could be correlated with device performance. In this work, we perform a comparative grain size experiment with $α$-Ta on $c$-axis sapphire. Our evaluation methods include both room-temperature chemical and structural characterization and cryogenic microwave measurements, and we report no statistical difference in device performance between small- and larger-grain-size devices with grain sizes of 924 nm$^2$ and 1700 nm$^2$, respectively. These findings suggest that grain size is not correlated with loss in the parameter regime of interest for Ta grown on c-axis sapphire, narrowing the parameter space for optimization of this materials set.

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Sarah Garcia Jones, Nicholas Materise, Ka Wun Leung, Brian D. Isakov, Xi Chen, Jiangchang Zheng, Andras Gyenis, Berthold Jaeck, Corey Rae H. McRae. 2023-07-25. Grain size in low loss superconducting Ta thin films on c-axis sapphire. https://arxiv.org/abs/2307.11667

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