Effect of rf sputtering on morphological and semiconductor properties of thin films of Yba2Cu3O7-δ

Using an off-axis configuration we have prepared in situ superconducting YBa2Cu3O7-delta (YBCO) thin films on SrTiO3 single-crystal (100) substrates. We have studied the effect of the distance from the target-substrate on the critical temperature (T-c) and current density (J(c)) of our films. Our best samples had T-c similar to 85 K and J(c) similar to 10(6) A/cm(2) at 20 K. Surface topography was examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM), showing the growth of spiral-shaped terraces. The height between steps was of the order of the c-axis length. Samples grown at not optimized positions presented non superconducting regions. The damage of this regions was related to the bombardment of negative oxygen ions or highly-energetic particles present in the plasma.