ACTA

Technology of Ultrathin NbN and NbTiN Films for Superconducting Photodetectors

M. Guziewicz^a, W. Slysz^a, M. Borysiewicz^a, R. Kruszka^a, Z. Sidor^a, M. Juchniewicz^a, K. Golaszewska^a, J.Z. Domagala^{a, b}, W. Rzodkiewicz^a, J. Ratajczak^a, J. Bar^a, M. Wegrzecki^a and R. Sobolewski^{a, c}
^aInstitute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw, Poland
^bInstitute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
^cDepartments of Electrical and Computer Engineering and Physics and Astronomy, Materials Science Program, and Laboratory for Laser Energetics, University of Rochester, Rochester, NY-14627-0231, USA

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We report fabrication and characterization of ultrathin NbN and NbTiN films designed for superconducting photodetectors. Our NbN and NbTiN films were deposited on Al₂O₃ and Si single-crystal wafers by a high-temperature, reactive magnetron sputtering method and, subsequently, annealed at 1000°C. The best, 18 nm thick NbN films deposited on sapphire exhibited the critical temperature of 15.0 K and the critical current density as high as ≈ 8 × 10⁶ A/cm² at 4.8 K.

DOI: 10.12693/APhysPolA.120.A-76
PACS numbers: 74.62.Bf, 74.78.-w, 81.15.Cd, 81.15.Jj