YBa2Cu3O7-δ (YBCO) thin films deposited by off-axis pulsed laser deposition could be used for fabricating multilayer devices. Growing YBCO films with high critical current density and high Tc (Tc is around 90 K and Jc is above 107 A/cm2 at 77 K), there was a tendency that the surface morphology of YBCO films is rough. This causes problems in fabricating multilayer devices that require a smooth surface. In this work, we have developed two-step procedures of growing YBCO thin films with high critical current and a smooth surface for multilayer device applications. In the two-step procedure, we first grew YBCO film with higher Tc (Tc is around 90 K, but usually the surface is with defects like holes), next we planarized the film by growing the film with lower Tc (Tc is around 83 K and the surface is smooth). YBCO films deposited at low temperatures have critical current densities (Jc) around 106 A/cm2 at 77 K in zero magnetic field. These films are almost free from laser droplets and outgrowth-free surface. In two-step procedures, we could grow films with a smooth surface and high critical current density. Methods for growing smooth surfaces in two-step procedures will be presented.
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