EFFECTS OF PLASMA ENHANCEMENT ON THE CARRIER-GAS-FREE METALORGANIC CHEMICAL-VAPOR-DEPOSITION OF OXIDE SUPERCONDUCTING THIN-FILMS

The effect of plasma enhancement on carrier-gas-flee metalorganic chemical vapor deposition of superconducting YBa2Cu3Ox films has been investigated based on crystallographic studies, plasma diagnosis, and composition analysis of the gas phase. With plasma enhancement, the oxygen pressure needed for growing thin films with YBa2Cu3Ox structure is reduced from 4.0X10(-2) to 2.0x10(-2) Pa. YBa2Cu3Ox films grown with plasma-enhancement at oxygen pressure of 4.0X10(-2) Pa showed zero resistivity at 86 K and a critical current density of 2x10(5) A/cm(2) at 77 K. Plasma enhancement also was found to increase oxidizing activity by three orders of magnitude during the cooling process. Plasma diagnosis indicated that superconducting properties of grown films are related to plasma density,which can in turn be related to the concentration of active oxygen. Composition analysis of the gas phase indicated that plasma enhancement increases reaction between oxygen and metalorganic sources or their derivatives. The effect of plasma enhancement on oxidizing activity clearly differs between growth and the cooling process, and this difference may be due to the consumption of activated oxygen by metalorganic sources or their derivatives.