High TC thin films with roughness smaller than one unit cell

We have developed a method for the growth of epitaxial high T, superconducting thin films with roughness smaller than one unit cell using conventional magnetron sputtering. In this method the substrate is positioned above one edge of the target (off axis) to avoid resputtering, and oscillated back and forth between the two symmetrical edges of the target to improve film thickness homogeneity. Finite size peaks in the x-ray diffraction spectra of thin GdBa@,O, _ 6 films and satellite peaks on a GdBa,Cu,O, _ flBa,C!u30, _ 6 superlattice show the excellent thickness control and smoothness obtained with this technique.