Growth and Properties of Double-Sided YBCO Films Deposited by Off-Axis Sputtering for Microwave Applications

The double-sided YBa2Cu3Oy (YBCO) films were grown on LaAlO3 (LAO) substrates by an off-axis magnetron sputtering system with two 2-inch sputtering guns. High-quality YBCO films within a 50-mm-diameter area were obtained. The homogeneous YBCO films revealed transition temperature Tc(R=0) of ≥86K and a critical current density Jc (zero field) of ∼1.5×106 A/cm2 at 77 K. Thesurface impedance of YBCO films was measured using a probe-coupling type microstripline resonator method. The surface resistance RS of ∼1.8 μΩ was obtained at 77 K around 2180 MHz. Additionally, a HTS three pole bandpass filter was fabricated and revealed a good microwave characteristic. The influence of surface roughness on microwave properties of YBCO films was discussed.