Sputter deposition of YBa2Cu3O6+x on alumina and the influence of ZrO2 buffer layers

The deposition of films of YBa2Cu3O6+x by rf diode sputtering on alumina has been investigated. Although a stoichiometric (123) target was employed, the film composition differs from that of the target and varies as a function of position on the substrate. Films displaying a broad resistive transition have been produced in a reproducible manner. It is demonstrated that the use of a ZrO2 buffer layer decreases the transition width significantly and consistently yields films which have a more metallic-like behavior above Tc.