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Improvement of the critical temperature of NbTiN films on III-nitride substrates
- Source :
- Supercond. Sci. Technol. 32 (2019) 035008
- Publication Year :
- 2018
-
Abstract
- In this paper, we study the impact of using III-nitride semiconductors (GaN, AlN) as substrates for ultrathin (11 nm) superconducting films of NbTiN deposited by reactive magnetron sputtering. The resulting NbTiN layers are (111)-oriented, fully relaxed, and they keep an epitaxial relation with the substrate. The higher critical superconducting temperature (Tc = 11.8 K) was obtained on AlN-on-sapphire, which was the substrate with smaller lattice mismatch with NbTiN. We attribute this improvement to a reduction of the NbTiN roughness, which appears associated to the relaxation of the lattice misfit with the substrate. On AlN-on-sapphire, superconducting nanowire single photon detectors (SNSPDs) were fabricated and tested, obtaining external quantum efficiencies that are in excellent agreement with theoretical calculations.
- Subjects :
- Physics - Applied Physics
Condensed Matter - Superconductivity
Subjects
Details
- Database :
- arXiv
- Journal :
- Supercond. Sci. Technol. 32 (2019) 035008
- Publication Type :
- Report
- Accession number :
- edsarx.1810.04070
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1088/1361-6668/aaf99d