EPITAXIAL YBA2CU3OX THIN-FILMS ON SAPPHIRE WITH A PRBA2CU3OX BUFFER LAYER

Highly c-axis-oriented YBa2Cu3Ox thin films have been grown on (1102BAR) sapphire substrates by a modified off-axis magnetron rf-sputtering technique. To prevent the interaction and to improve the lattice match between film and substrate a thin layer of 10-60 nm of PrBa2Cu3Ox was used as a buffer layer. The diffusion process was effectively blocked and the epitaxy was enhanced. The J(c) (77 K) has been measured to be 4 x 10(5) A/cm2 which is significantly higher than the J(c) of films directly grown on Al2O3 (approximately 8 x 10(4) A/cm2). The surface resistance of such films at 11 GHz and 4.2 K was measured to be 80-mu-OMEGA for 50-nm thin films. These results are comparable to the best results reported so far on sapphire with other buffer layers.