OPTIMIZATION OF THE SURFACE-MORPHOLOGY OF MAGNETRON-SPUTTERED Y1BA2CU3O7-X FILMS

We demonstrate that the surface morphology of 20-200-nm-thick magnetron-sputtered Y1Ba2Cu3O7 films can be optimized by careful control of the plasma current. The optimization can be performed at different substrate temperatures allowing us to maximize the transition temperature T(c) and the homogeneity of the films independently from the optimization of the surface morphology. This sequence allows us to retain the characteristic high T(c) values (T(c)>90 K, J(c)>10(6) A/cm2 at 77 K). To obtain very thin films (<40 nm) with similar superconducting properties, the deposition temperature has to be ramped during the sputter process.