Microwave properties of YBa 2Cu 3O 7−x deposited on MgO substrates

Abstract

With pre-annealed treatments, high density of atomic steps were formed on the surface of the MgO substrate. The early-stage microstructure of YBa 2Cu 3O 7−x thin films was evolved with a step-flow growth mode by pulsed laser deposition. On the as-polished MgO substrates the Volmer-Weber-type island growth mode was dominant. By means of microstrip line measurement, it was found that the films grown on the pre-annealed substrate not only have a higher critical current densities but also have a lower microwave loss than those of films deposited on as-polished substrate. The distinction existed even when the deposition condition were not optimized.