In-situ growth of YBa2Cu3O7-x superconducting thin films on (001) MgO by laser ablation method

A KrF uniform beam excimer laser has been successfully applied to in-situ grow YBa2Cu3O7-x superconducting films on (001) MgO substrate. A special designed stainless steel ring placing between substrate and target was used to supply highly uniform flow of N2O gas to the laser plume and substrate during deposition. The substrate temperature was kept at 620degC. The thicknesses of the films are 500-2000A. Typical values of Tc onset, Tc zero and transition width (90%-10%) were measured to be 91, 90, and 1K, respectively. The transport critical current density was measured to be above 3x106A/cm2 at 77K, without magnetic field. The as-deposited films are smooth, shiny and black with a mirror-like surface morphology. It was found that the surface morphology of thin films prepared by a laser ablation method were highly dependent on the processing parameters. (orig.)