Enhancement of dislocation density in YBa₂Cu₃O_y thin films prepared by low temperature growth technique

In order to achieve further lower substrate temperature (T_s) of YBa₂Cu₃O_y (YBCO) thin films for coated conductor application, we developed low temperature growth (LTG) II technique. In the LTG II technique, a c-axis oriented (Yb_1-xNd_x)Ba₂Cu₃O_y thin layer was deposited on MgO substrate as seed layer at low T_s and then YBCO layer was fabricated on the seed layer at the same T_s. As a result, we achieved that the LTG II-YBCO thin films showed complete c-axis orientation at lower T_s than that for obtaining c-axis oriented PLD-YBCO thin films by 15 °C, and showed a high J_c. We discussed the orientation mechanism of the LTG II-YBCO thin film using a simple nucleation model.