Effect of glow discharge current on composition of Y-Ba-Cu-O films by high pressure DC sputtering process

The Y-Ba-Cu-O (YBCO) films were grown on (100 MgO substrate by the high pressure DC diode sputtering process. The targets were YBCO compounds made by solid-state reaction. The sputtering gas was Ar-50% O2, and total pressure was 1.5 torr. As-deposited superconducting YBCO films can be prepared at low substrate temperature at high discharge current. For Y1Ba2Cu3Ox target, the atomic ratio Ba/Y in the films almost remains constant (Ba/Y = 1.7) and Cu content monotonically increases with increasing discharge current. The Cu content in the film approaches to that of the target at low discharge current. Concentrations of O and O2+ in plasma markedly increase during increase of discharge current. High Cu content at large discharge current may be caused by action of electrical field on Ba+ and Y+