Effect of target composition on the crystallinity of YBa2Cu3Oy epitaxial films fabricated by Nd : YAG pulsed laser deposition

We have studied the influence of atomic composition of the targets on the c rystallinity of the YBa2Cu3Oy films deposited by the Nd:YAG pulsed laser ab lation technique. The films deposited by using a target that has a stoichio metric ratio show superconductivity with a transition temperature of 90.0+/ -0.5 K. They are epitaxially grown with c-axis orientation. The films depos ited from six targets whose composition is deviated by +/-5% for every meta l element have also shown a good c-axis orientation and a slightly low tran sition temperature in the range 82-89 K. In this case, however, formation o f amorphous material occurs, resulting in deterioration of the crystallinit y. In addition, a number of CuO, BaO and BaCu2O2 impurity particles appear on the film surface. From these results, it has been confirmed that the ato mic composition of the fabricated films does not largely shift from that of the target in the laser ablation method. The target with 1:2:3 composition should be used to fabricate high-quality films. (C) 2000 Elsevier Science B.V. All rights reserved.