Growth of high-T_c YBa₂Cu₃O_y films with an off-axis sputtering configuration

Using an off-axis rf sputtering configuration, we have prepared in situ high-T_c YBa₂Cu₃O_7-y (YBCO) films with a relatively large deposition rate. The sputtering gas was a mixture of Ar and O₂ (7:3) and the substrates were MgO(100) and SrTiO ₃(100). We found that the distance from the target to the substrate, d, is a key factor in the deposition rate. By decreasing d to a value of about 1.5-2.5 cm, we obtained a deposition rate as great as 2000-2500 Å per hour with an rf power of 120 W and at a total pressure 100-200 mTorr. The transport behaviors of the as-grown YBCO films under magnetic fields are reported. The activation energy derived from the resistive transition in magnetic fields is thickness dependent.