Preparation of Ca-Doped YBaCuO Thin Films Containing 248 Phase by RF Magnetron Sputtering

Ca-doped YBaCuO thin films containing predominantly a 248 phase were prepared on SrTiO3(100) substrates by sputtering three Ca-doped targets at 500°C and annealing at 750°C. The as-deposited films formed at above 500°C predominantly had a 123 phase, and those at 300°C were amorphous. On the other hand, the as-deposited films obtained at 400–500°C had an unidentified major phase with a lattice spacing of 7 Å, which changed into a 248 phase by annealing, whereas the phase of amorphous films and the 123 phase did not.