Preparation and electrical properties of ultra-thin Bi2212 films by sol-gel method

Abstract

In order to achieve flexible applications of superconducting thin film materials in devices, the surface quality of the film is critical. The thickness of the film is one of the important factors affecting its surface quality. In this paper, Bi2212 superconducting thin films of different thicknesses were prepared on LaAlO3(100) and SrTiO3(100) single crystal substrates by sol-gel method and the effects of film thickness and different heterogeneous structures on their crystallographic, morphological and superconducting properties were investigated. The results showed that the roughness gradually increased with increasing Bi2212 thickness at the initial stage of film growth and stabilized after reaching a certain thickness, while the superconducting properties were destroyed at very small sample thickness, which was consistent in both single-crystal substrate films. In the Bi2212/LaAlO3 structure, the surface quality of the sample was excellent with a roughness of 5.4 nm at a thickness of about 18 nm for Bi2212, and the growth of the precipitated phase was inhibited to a greater extent. The film also had good superconductivity. This work provided a further research basis for the preparation of high quality Bi2212 films and offers further possibilities for their practical application.