Dependence of the microwave surface resistance on the structure and thickness of superconducting cuprate films

An investigation is made of the microwave surface resistance R-s measured a t 10 GHz and 77 K, as a function of the thickness of superconducting epitax ial films of yttrium barium cuprate grown on lanthanum aluminate substrates by magnetron sputtering. Films between 200 and 1800 nm thick have low valu es R-s (0.3-0.5) m Omega and do not show any deterioration. The level of R- s achieved in films of comparatively large thickness is mainly attributable to the low rate of film growth (0.8 nm/min). (C) 1999 American Institute o f Physics. [S1063-7850(99)01408-1].