Fabrication and post-annealing studies of ultrasonically spray pyrolysed Y-Ba-Cu-O films

An ultrasonic spray pyrolysis (USP) system has been used to deposit thick films of YBa/sub 2/Cu/sub 3/O/sub 7-x/ on [100] LaAlO/sub 3/. Nitrate precursors with a Y:Ba:Cu ratio of 1:2:0.6 have been used with a deposition temperature of 900/spl deg/C and annealing temperature of 500/spl deg/C. Growth rates as high as 1 /spl mu/m per minute have resulted in epitaxial growth of biaxially aligned (<3/spl deg/), 3 /spl mu/m thick YBa/sub 2/Cu/sub 3/O/sub 7-x/ films, with typical endpoint T/sub c/ of /spl sim/86 K and onset T/sub c/ of /spl sim/91 K and J/sub c/, of >10/sup 4/ A.cm/sup -2/, 1 T, 77 K. It has been previously shown that lower nitrate precursor concentration, and hence decreased growth rate, has resulted in improved superconducting properties. The main objective of this paper is to investigated the effect of deposition temperature and post-annealing on the properties of the superconducting films.