Microstructural and morphological analysis of ultrathin YBa 2 Cu 3 O 7−x films grown by modulated magnetron sputtering on SrTiO 3 substrates

The defect structure, the degree of crystalline perfection and the surface roughness of HTc superconductor films are affected by the initial layer configuration at the early stage of growth. In this work we report on structural and morphological investigations of ultrathin YBa 2 Cu 3 O 7−x films grown on SrTiO 3 substrate. The films are fabricated by inverted cylindrical magnetron sputtering with a modified deposition process based on the modulation of sputtering power. The modulated sputtering deposition promotes a higher in-plane grain connectivity and allows us to fabricate films with a lower defect density. The structural analyses of very thin films (thickness