Comparison of microwave properties of YBCO films on MgO and LaAlO3 substrates

To obtain low loss and better performance of high temperature superconducting (HTS) microwave devices, higher quality HTS thin films are required. As it is well known, properties of HTS films and effects of temperature, frequency and microwave power on the properties depend on the type of substrate used and the method of deposition. YBa2Cu3O7−δ (YBCO) films on lanthanum aluminate (LAO) are considered to have lowest losses, and are commonly used for HTS planar filters for cellular phone base stations. We have measured the surface resistance (Rs) of high quality YBCO thin films, deposited on LAO and MgO substrates, as a function of frequency, temperature and microwave power to assess the quality of YBCO films on the lower cost MgO substrates for possible applications in communication systems