抄録
The preparation conditions for as-deposited superconducting films of Y-Ba-Cu-O have been investigated. By DC magnetron sputtering using single sintered targets with different compositions, films have been deposited onto heated substrates of single crystal MgO and further have been heat-treated at 450-550°C for 30 minutes in an oxygen pressure of 160 Torr during the course of cooling. The film thickness ranges from 100 to 6, 000Å. The rate of deposition for Y-Ba-Cu-O films highly depends on the oxygen partial pressure PO2 and total gas pressure PAr+O2. A small increase in PO2 from 0.1 to 10m Torr anomalously reduces the deposition rate, despite high PAr+O2 exceeding 200m Torr. However, in the case of PAr+O2=300m Torr, the deposition rate becomes constant with increasing the PO2 to above 1m Torr and the resputtering effect seems to be reduced. Ba-poorer targets than stoichiometry normally provide films with high-Tc (transition temperature) and low ρn (normal state resistivity). The distance L between target and substrate has also a benefical effect on the growth of high-Tc films and depositions at L=38mm provide high-Tc films with c-axis preferred orientation and homogeneous surface. The maximum zero resistance temperature Tc, end reaches 87K and even thin films with thicknesses of -500Å still maintain Tc, end above 85K.
