Raman studies of reactive DC-magnetron sputtered thin films of YBaCuO on MgO

Raman spectroscopy was employed to study Y–Ba–Cu–O films prepared by multilayer, reactive sputtering from separate Y, Cu, and Ba0.5Cu0.5 targets. A set of films having the composition YxBa2CuyOz with 0.7 < x < 1.8 and 2.8 < y < 3.5 and critical temperature with zero resistance, Tc(R = 0), ranging from 25 to 90 K was studied with the Raman technique. The correlation between Raman data and critical temperature, Tc, was investigated. This technique provides important information concerning the film crystallinity, homogencity, and impurity content (including other phases) which is useful in judging the quality of high Tc superconducting films. We also found that the rapid thermal annealing process is a very efficient way to reduce chemical reactions between the film and the substrate.