モザイクターゲットをもちいた基板ホルダバイアスRFスパッタ法によるY-Ba-Cu-O系In Situ薄膜の製作と超伝導特性

概要

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In situ grown superconducting Y-Ba-Cu-O films were deposited on a MgO substrate by rf sputtering with dc biased substrate holder using a mosaic YBaxCuyOztarget, which was composed of 9 pieces of ceramic of a nominal composition of x = 2, 4, 6, and y =3, 5, 7. The films were deposited at a substrate temperature Ts of 660°C and at various substrate holder voltages VH. After deposition, the films were immediately cooled in the chamber vented with 400 Torr of oxygen. The dependence of the critical temperature on the substrate position was investigated. The critical temperature higher than 70K was obtained at the substrate position above the target composition of x=2-6 and y=3-5 for VH= -80 V to -120 V.The deposition rate at finite negative holder voltage was higher than that at zero holder voltage. It was shown that the film composition approached to the target composition by the substrate holder negative voltage. The film with short c-lattice parameter showed high Tc, but the shortest one was somewhat longer than the bulk value.