BARRIER AND ELECTRODE PROPERTIES OF HIGH T(C) JOSEPHSON-JUNCTIONS FORMED BY A PLASMA DISCHARGE PROCESS

The influence of rf discharge in CF4 and O2 gases on the properties of thin YBCO films and edge junctions was investigated by transport meas urement and Auger spectroscopy. It was found that oxygen plasma of sho rt duration can serve as a cleaning step before the formation of the b arrier. In contrast, CF4 plasma tends to substitute oxygen in the supe rconducting film by fluorine which yield an insulating layer. A CF4 pl asma discharge of more than one minute turns the YBCO film irreversibl y into an insulator. At shorter durations, the deterioration of the fi lms is limited to a thickness of the order of few tens of angstroms.