Synthesis and characterization of niobium carbide thin films on diamond surface for superconductive application

• Published in: Journal of alloys and compounds 2024-03, Vol.976, p.173266, Article 173266
• Main Authors: Khmelnitsky, R.A., Martovitsky, V.P., Bondareva, J.V., Kolbatova, A.I., Titova, N.A., Goltsman, G.N., Fedorov, F.S., Egorov, A.V., Matsokin, N.A., Kvashnin, A.G., Kvashnin, D.G., Evlashin, S.A.
• Format: Article
• Language: English
• Subjects: Diamond metallization; Niobium carbide; Superconductivity; Thin films
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.173266

Diamond's unique properties make it attractive for use in a variety of industrial applications. However, this material has not found mass application in microelectronics due to several factors, including the lack of large-sized plates, n-type doping, and high-quality metallization. In this article, we address the problem of diamond surface metallization by forming niobium carbide layers. We obtained a niobium carbide film several nanometers thick that exhibits superconducting behavior up to 12.4 K. To our knowledge, this is the highest superconducting transition temperature achieved in the niobium carbide system. The crystal lattice parameter of the film is 4.4659 Å, which is close to the maximum value for niobium carbide lattice parameters. Density functional theory calculations were employed to investigate the thermodynamic stability of niobium carbide compounds at various temperatures and determine the superconducting critical temperature of niobium carbide. The combination of diamond's high thermal conductivity, along with the strong adhesion and superconductivity of niobium cabide films, introduces exciting possibilities for the realization of superconductive sensitive detectors. [Display omitted] •Adhesion-strong films of stoichiometrically perfect NbC were obtained by niobium deposition and subsequent annealing.•Observation of phase transformation of niobium into niobium carbide during annealing.•Deposition of niobium at high temperatures leads to good adhesion and formation of continuous nanocrystalline films.•The obtained niobium carbide film several nanometers thick exhibits superconducting behavior up to 12.4 K.•The lattice parameter of the film is 4.4659 Å, which is close to the maximum value for the lattice parameters of NbC.