As-grown Y-Ba-Cu-O thin films by reactive coevaporation with oxygen plasma cooling

We have developed a new fabrication process of as-grown Y-Ba-Cu-O thin films using a reactive coevaporation method specially with the rf-plasma cooling in the low oxygen pressure of 0.4 mTorr. By this O2 plasma cooling process, the transition temperature Tc is improved from 40 to 81 K for the film with a thickness of 1000 Å. The x-ray diffraction analysis shows that the activated oxygen species generated by the rf plasma make Y-Ba-Cu-O films oxidize sufficiently even in the low pressure of oxygen. In addition, we have studied the thickness dependence of Tc for as-grown films with various thicknesses of 60–2000 Å.