The Growth of (00l)-Oriented CeO₂ Buffer Layers on R-Cut Sapphire Substrates for the Epitaxy of Tl-2212 Superconducting Films

Abstract

Tl-2212 superconducting films were fabricated on r-cut sapphire substrates buffered with (00l)-oriented CeO2 films. The buffer layers were deposited by the cerium dioxide sputtering target and the RF magnetron sputtering method. The epitaxial growth of CeO2 films on r-cut sapphire substrates was obtained over a wide range of sputtering parameters, such as temperature, pressure, power and Ar/O2 ratio. The Tl-2212 films grown on these buffer layers subsequently were purely c-axis orientation. The critical transition temperature of the best film was 105.6 K, the critical current density was 2.8 MA/cm2 (77 K, 0 T) and the surface resistance was 435 μΩ (10 GHz, 77 K).