Sequentially evaporated YBa2Cu3O7-x high temperature superconducting thin films on microwave substrates

The application of high critical temperature superconducting thin films in microwave systems is of great interest due to their potential for high quality factors and low insertion losses. For this purpose, the formation of thin films of YBa2Cu3O7-x on SrTiO3, LaAlO3, MgO, and ZrO2 coated sapphire and alumina substrates by sequential evaporation of multiple layers of Cu, BaF2 and Y, with subsequent annealing in oxygen has been investigated. Films formed by this technique have been characterized by resistance-temperature measurements, energy dispersive x-ray spectroscopy, x-ray diffraction and scanning electron microscopy. Films deposited on LaAlO3 substrates have also been patterned into a 35 GHz microstrip ring resonator. Measurements of the scattering parameters of the resonator have been used to assess the suitability of these films for microwave applications. (orig.)