Abstract
Two-inch-diameter CeO 2 films on R-plane (1102) sapphire substrates have been prepared using an on-axis rf magnetron sputtering method. The effects of postannealing treatment, sputtering gas pressure and substrate temperature on the orientation, crystallinity and surface morphology of the CeO 2 films have been investigated. The (100)-preferred CeO 2 films with high crystallinity are grown at 820°C and 0.15 Torr and have a full width at half-maximum value of the rocking curve of (200) planes of 0.15°. The spatial variation of thickness of the CeO 2 films across the 2-inch substrate is about 5.8%. The c-axis oriented YBa 2 Cu 3 O x (YBCO) films grown on sapphire substrates with a (100)-preferred CeO 2 buffer layer of 100 nm are made. The YBCO films have superconducting properties with the T c being 88-90 K and J c (77 K, 0 T) being (1-3) × 10 6 A/cm 2 .