Mirror-smooth YBa2Cu3O7−x superconducting films deposited by plasma-enhanced pulsed laser deposition technique

Effect of microwave induced O2- and Ar-plasma on characteristics of YBa2Cu3O7−x (YBCO) superconducting films deposited by pulsed laser deposition technique (PLD) was examined. Surface roughness of the films was greatly improved at the presence of O2-plasma, but was substantially degraded at the presence of Ar-plasma. Epitaxial-like YBCO superconducting films with c-axis perpendicular to the filmsʹ surface and with a- and b-axes aligned in filmsʹ plane were obtained on (100) MgO substrates. They have onset of transition temperature at Tc = 90 K and zero at Tc0 = 86 K. The mechanism for the improvement in this process was investigated by optical emission microscopy (OEM). The production of abundant atomic oxygen in microwave induced oxygen plasma that enhances the surface reaction kinetics is believed to be the main factor for improving surface smoothness of the films.