Optimization of YBCO surfaces of tunnel junctions

It is established that in YBa/sub 2/Cu/sub 3/O/sub 7/ films prepared by annealing amorphous oxide deposits, Ba segregation in the amorphous phase and YBCO decomposition after recrystallization are the major causes of surface degradation. The authors have grown films by entirely in-situ processing in which these effects are minimized. The films were epitaxially grown on