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 crystallinity of the YBa2Cu3Oy films deposited by the Nd:YAG pulsed laser ablation technique. The films deposited by using a target that has a stoichiometric ratio show superconductivity with a transition temperature of 90.0+/-0.5 K. They are epitaxially grown with c-axis orientation. The films deposited from six targets whose composition is deviated by +/-5% for every metal element have also shown a good c-axis orientation and a slightly low transition temperature in the range 82-89 K. In this case, however, formation of amorphous material occurs, resulting in deterioration of the crystallinity. 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 atomic 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.