Effects of DC bias voltage in sputter deposition of YBaCuO films

YBaCuO thin films with c-axis orientation have been deposited on (100) oriented SrTiO ₃ substrates by DC bias sputtering using a stoichiometric ceramic hollow cylinder as a target. The effects of the applied voltage on structural and electrical properties of the films have been investigated. Up to a threshold of 35 V the films had transition temperatures T _c around 90 K and bulk c-axis lattice parameters. Above this threshold the ion bombardment during growth causes a depression of T _c and the critical current density j _c, a c-axis lattice parameter expansion, a broadening of the x-ray diffraction peaks and an increase of the resistivity. These results can be explained qualitatively by various oxygen- and cation-disorder models.