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| Main Authors: | , , , , , , |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2306.15258 |
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| _version_ | 1866929278496538624 |
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| author | Urade, Yoshiro Yakushiji, Kay Tsujimoto, Manabu Yamada, Takahiro Makise, Kazumasa Mizubayashi, Wataru Inomata, Kunihiro |
| author_facet | Urade, Yoshiro Yakushiji, Kay Tsujimoto, Manabu Yamada, Takahiro Makise, Kazumasa Mizubayashi, Wataru Inomata, Kunihiro |
| contents | Tantalum thin films sputtered on unheated silicon substrates are characterized with microwaves at around 10 GHz in a 10 mK environment. We show that the phase of tantalum with a body-centered cubic lattice ($α$-Ta) can be grown selectively by depositing a niobium buffer layer prior to a tantalum film. The physical properties of the films, such as superconducting transition temperature and crystallinity, change markedly with the addition of the buffer layer. Coplanar waveguide resonators based on the composite film exhibit significantly enhanced internal quality factors compared with a film without the buffer layer. The internal quality factor approaches $2\times 10^7$ at a large-photon-number limit. While the quality factor decreases at the single-photon level owing to two-level system (TLS) loss, we have identified the primary cause of TLS loss to be the amorphous silicon layer at the film-substrate interface, which originates from the substrate cleaning before the film deposition rather than the film itself. The temperature dependence of the internal quality factors shows a marked rise below 200 mK, suggesting the presence of TLS-TLS interactions. The present low-loss tantalum films can be deposited without substrate heating and thus have various potential applications in superconducting quantum electronics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2306_15258 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Microwave characterization of tantalum superconducting resonators on silicon substrate with niobium buffer layer Urade, Yoshiro Yakushiji, Kay Tsujimoto, Manabu Yamada, Takahiro Makise, Kazumasa Mizubayashi, Wataru Inomata, Kunihiro Quantum Physics Applied Physics Tantalum thin films sputtered on unheated silicon substrates are characterized with microwaves at around 10 GHz in a 10 mK environment. We show that the phase of tantalum with a body-centered cubic lattice ($α$-Ta) can be grown selectively by depositing a niobium buffer layer prior to a tantalum film. The physical properties of the films, such as superconducting transition temperature and crystallinity, change markedly with the addition of the buffer layer. Coplanar waveguide resonators based on the composite film exhibit significantly enhanced internal quality factors compared with a film without the buffer layer. The internal quality factor approaches $2\times 10^7$ at a large-photon-number limit. While the quality factor decreases at the single-photon level owing to two-level system (TLS) loss, we have identified the primary cause of TLS loss to be the amorphous silicon layer at the film-substrate interface, which originates from the substrate cleaning before the film deposition rather than the film itself. The temperature dependence of the internal quality factors shows a marked rise below 200 mK, suggesting the presence of TLS-TLS interactions. The present low-loss tantalum films can be deposited without substrate heating and thus have various potential applications in superconducting quantum electronics. |
| title | Microwave characterization of tantalum superconducting resonators on silicon substrate with niobium buffer layer |
| topic | Quantum Physics Applied Physics |
| url | https://arxiv.org/abs/2306.15258 |