Fabrication of YBa{sub}2Cu{sub}3O{sub}y thin films by YAG pulsed laser ablation method -influence of the target composition-ratio on the quality of films-

摘要

In order to improve the surface quality of YBa{sub}2Cu{sub}3O{sub}y film deposited by YAG pulsed laser-ablation technique we have studied the influence of atomic composition of the targets on the creation of surface-particles and crystallinity of the film and obtained the following results. The films deposited by using a target which has an atomic ratio of Y : Ba : Cu = 1 : 2 : 3 show superconductivity with a transition temperature of 90.0 K. They are epitaxially grown showing c-axis orientation.In addition the number density of particles is as low as 1.5 particles / 10μm{sup}2. The films deposited from the target whose composition is deviated by 5% for every metal element have also showed a good c-axis orientation and a high transitiontemperature in the range of 82-89K. In this case, however, formation of amorphous material occurs resulting in deterioration of the crystallinity. In addition. a number of CuO, BaO, and BaCu{sub}2O{sub}2 particles appear on the film surface. From theseresults. it has been clarified that the atomic composition of the fabricated films don't largely shift from that of the target in the laser ablation method and also that the target with 1:2:3 composition should be used to fabricate the high quality films.