Ultrathin rock-salt type NbN films grown on atomically flat AlN/sapphire substrates

• Published in: Journal of crystal growth Vol. 572; p. 126269
• Main Authors: Kobayashi, Atsushi, Ueno, Kohei, Fujioka, Hiroshi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2021; Elsevier BV
• Subjects: A1. High resolution X-ray diffraction; A1. Reflection high energy electron diffraction; A3. Physical vapor deposition processes; B1. Nitrides; B2. Semiconducting III-V materials; B2. Superconducting materials; Electrical properties; Electron diffraction; High energy electrons; Niobium nitride; Sapphire; Substrates; Superconductivity; Transition temperature; A3. Physical vapor deposition processes; A1. Reflection high energy electron diffraction; B1. Nitrides; A1. High resolution X-ray diffraction; B2. Semiconducting III-V materials; B2. Superconducting materials
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2021.126269

•An ultrathin NbN film on AlN exhibits a step-and-terrace structure on the surface.•The NbN exhibited distinct streaky RHEED patterns and reasonable XRD diffraction.•The Tc of the 7-nm-thick NbN was 11.3 K. In this study, we grew NbN(111) films on AlN(0001)/sapphire substrates by sputtering and investigated their structural and electrical properties. It was found that a 7-nm-thick NbN film grown on an AlN/sapphire substrate at 850 °C had a step-and-terrace structure on the surface, similar to that of the underlying AlN surface. Reflection high-energy electron diffraction and X-ray diffraction revealed the high crystallinity of the ultrathin NbN film. The superconducting transition temperature of the 7-nm-thick NbN was 11 K, which is lower than that of the 27-nm-thick NbN film grown at the same temperature, but sufficient to be applicable to superconducting single-photon detectors.