MICROWAVE PROPERTIES OF YBA2CU3O7-X DEPOSITED ON MGO SUBSTRATES

With pre-annealed treatments, high density of atomic steps were formed on the surface of the MgO substrate. The early-stage microstructure o f YBa2Cu3O7-x thin films was evolved with a step-flow growth mode by p ulsed laser deposition. On the as-polished MgO substrates the Volmer-W eber-type island growth mode was dominant. By means of microstrip line measurement, it was found that the films grown on the pre-annealed su bstrate not only have a higher critical current densities but also hav e a lower microwave loss than those of films deposited on as-polished substrate. The distinction existed even when the deposition condition were not optimized.