Effect of Sputter Gas Pressure and RF Power on Surface Morphology of CeO2 Buffer Layers and Superconducting Properties of EuBa2Cu3O7-δ Thin Films by Magnetron Sputtering

The deposition rate (Rd) of a CeO2 buffer layer fabricated at substrate temperature of 650 °C by RF magnetron sputtering was controlled by adjusting sputtering gas pressure and RF power, and the effect of Rd on the surface morphologies of the CeO2 buffer layer was examined. In addition, the superconducting properties of EuBa2Cu3O7-δ (EBCO) thin films deposited on buffer layers with different surface morphologies were examined. With a sputtering gas pressure of 3 Pa, Rd changed from 1 to 8 nm/min when the RF power was changed from 100 to 475 W. However, a CeO2 buffer layer of 300 nm thickness composed of very minute a-axis-oriented grains grew at any RF power. At 7 Pa, even though Rd was equivalent to that at 3 Pa, grains with facets grew regardless of the RF power. A c-axis-oriented EBCO thin film grew on the CeO2 buffer layer on which minute grains grew, and the (110) or (103) axis growth of EBCO was observed on the buffer layer on which grains with facets grew.