DEPOSITION OF YBA2CU3O7-DELTA THIN-FILMS OVER LARGE AREAS WITH A SIMPLE SPUTTERING TECHNIQUE FOR MICROWAVE APPLICATIONS

dA simple sputtering technique is presented for the fabrication of YBa 2Cu3O7-delta (YBCO) films over large areas. The magnetron sputtering s ource combines operation in an unbalanced magnetic field configuration and use of large YBCO targets. YBCO films were deposited on LaAlO3 (1 00) substrates with sizes up to 1 in x 1 in. The films are characteriz ed by x-ray diffraction, pole figures, ac susceptibility, transport pr operties and thickness uniformity. The results show that these films a re of good quality with perfect c-axis orientation, epitaxial growth, critical temperature of greater than or equal to 90 K, critical curren t density of greater than or equal to 1 x 10(6) A cm(-2) at 77 K and t hickness uniformity better than 5% over an 1 in x 1 in substrate. A tw o-pole bandpass filter with centre frequency of 13 GHz and 3 dB fracti onal bandwith of about 15% was designed to test the microwave performa nce of these films. A YBCO filter exhibits at 77 K an insertion loss o f more than 5 dB lower than an equivalent Au filter on LaAlO3 substrat e at the same temperature.