Deposition of YBa2Cu3O7-delta thin films over large areas with a simple sputtering technique for microwave applications

摘要

dA simple sputtering technique is presented for the fabrication of YBa2Cu3O7-delta (YBCO) films over large areas. The magnetron sputtering source combines operation in an unbalanced magnetic field configuration and use of large YBCO targets. YBCO films were deposited on LaAlO3 (100) substrates with sizes up to 1 in x 1 in. The films are characterized by x-ray diffraction, pole figures, ac susceptibility, transport properties and thickness uniformity. The results show that these films are of good quality with perfect c-axis orientation, epitaxial growth, critical temperature of greater than or equal to 90 K, critical current density of greater than or equal to 1 x 10(6) A cm(-2) at 77 K and thickness uniformity better than 5% over an 1 in x 1 in substrate. A two-pole bandpass filter with centre frequency of 13 GHz and 3 dB fractional bandwith of about 15% was designed to test the microwave performance of these films. A YBCO filter exhibits at 77 K an insertion loss of more than 5 dB lower than an equivalent Au filter on LaAlO3 substrate at the same temperature. [References: 21]