スパッタ法による高温超伝導薄膜の作製と評価
1988 年 9 巻 7 号 p. 535-540
詳細
1988 年 9 巻 7 号 p. 535-540
Y-Ba-Cu-O films were deposited on polycrystalline YSZ substrates by rf sputtering. Two types of targets were employed for the deposition. The as-sputtered films were insulators, but they became superconductive after being annealed in oxygen at 900°C for 3h. The plasma oxidation was performed in a mixture gas of Ar-50% O2 at 15mTorr by using the anti-sputtering in the same vessel as used for deposition; the rf power was 25W. The oxidation raises Tc and lowers the resistance ratio R (100K) /R (300K) of the films. The best films obtained so far exhibited a superconducting onset at 94K and zero resistance at 82K.
Aging effect of the films at room temperature was also investigated. The higher Tc and the lower ratio R (100K) /R (300K) were maintained over a period of more than 30 days in dry air. This indicates that the impovement by the oxidation was not temporary.
