Preparing Ultrathin MgB₂ Thin Film by Ex Situ Annealing of Mg-B Precursor Film

Abstract:

Ultrathin MgB₂ film is essential for the fabrication of MgB₂ superconducting single photon detectors (SSPDs). In this paper, we prepared 20nm and 10nm MgB₂ film using ex-situ annealing of Mg-B multilayer method. The precursor films were prepared by electron beam evaporation. A flowing Mg vapour and H₂ was introduced in the annealing process to keep MgB₂ thin film thermodynamically stable. The annealing temperature was between 680 and 740 and annealing time was 1-10min. 20nm MgB₂ films on MgO(111) substrates had the critical temperature (T_c) of 32.2K. The films grew along c-axes direction. As the substrate changed to SiC(001) and Al₂O₃(001), T_c decreased to 30.3K and 10.2K respectively. For 10nm MgB₂ film on SiC(001) substrate, T_c was 24.2K. The self-field critical current density for 10nm and 20nm film on SiC(001) substrate was 2.1×10⁶A/cm² and 2.3×10⁶A/cm², respectively. AFM image showed that the film had a flat surface with mean roughness of 0.899nm for 10nm MgB₂ film.

• Periodical: Materials Science Forum (Volumes 745-746)
• Pages: 249-254
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.745-746.249
• Online since: February 2013
• Authors: Qian Dai, Ruo Run Ma, Qing Rong Feng, Huai Zhang, Qian Qian Yang, Rui Juan Nie, Fu Ren Wang
• Keywords: MgB₂, Superconducting Film, Ultrathin Film

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