Growth of YBa2Cu3O7 superconductor thin films using ethanolamine-based solutions via simple spin coating

A simple spin coating technique was used to deposit YBa2Cu3O7 (YBCO) thin films on glass substrates using an ethanolamine-based solvent, which is a relatively safe, nontoxic, fluorine-free, and inexpensive solvent used in the production process of yttrium barium copper oxide (YBCO) superconductors. In this study, high quality YBCO thin films fabricated via spin coating under varying deposited gel film annealing temperatures are proposed. Moreover, YBCO thin films were obtained at a low annealing temperature of at least 400 °C. The X-ray diffraction analysis spectra of the fabricated YBCO thin films revealed various unique YBCO peaks at 23°, 32°, and 40°, respectively. Additionally, we observed that the diffraction intensity of each YBCO peak increased as the annealing temperature increased. As the annealing time became longer at 800 °C, the c-axis of the YBCO oriented peak became stronger. Consequently, the higher annealing temperature was assumed to have resulted in the enhancement of the YBCO crystal growth. In contrast, a longer annealing time enhanced the re-growth of the YBCO crystal to the c-axis orientation. In secondary electronic spectroscopy (SEM) images of the YBCO thin film and substrate cross sections, the obtained YBCO thin film thickness was approximately 3 µm for both high and low annealing temperature samples. The obtained cross section of the YBCO thin film images was flat and clear. This study established that annealing temperature and time are very important factors for obtaining high quality YBCO thin film crystals. Additionally, we assumed that annealing temperature and time are important parameters for obtaining highly oriented YBCO thin film crystals.