溅射气体中氩气含量对Y_1Ba_2Cu_3O_(7-δ)薄膜结构和T_c的影响

Influence of Ar Ratio in Sputtering Gas on Structure and T_c of Y_1Ba_2Cu_3O_(7-δ) Thin Film

采用倒筒直流磁控溅射系统在不同溅射气体组分下(氩氧比不同)原位沉积Y1Ba2Cu2O7-δ(YBCO)薄膜。样品的XRD分析发现在Ar含量过高和过低的溅射气氛下沉积的薄膜存在极少量的BaCuO2第二相,同时显示薄膜的c轴长度,(006),(007)对(005)峰强度比随着溅射气体中Ar含量的变化而发生改变。通过薄膜超导零电阻温度检测发现,YBCO薄膜的超导零电阻温度Tc随之发生改变。这说明在磁控溅射沉积YBCO薄膜过程中,溅射气体中Ar气含量影响薄膜各元素的化学计量比,Ar含量过高和过低导致沉积YBCO薄膜晶体结构发生畸变,恶化超导电性。

In-suit inverted cylindrical DC magnetron sputtering system was adopted to deposit YBCO thin film, with different sputtering gas compositions (different Ar and O_2 ratio). XRD analysis of samples shows that small amount of BaCuO_2 second phase exists in thin films obtained under ultra high Ar ratio and ultra low sputtering atmosphere. At the same time, the length of c-axis, the ratio of XRD peak intensities of (006) (007) versus that of (005) vary with Ar ratio. We find that T_c of YBCO thin film varies also as Ar ratio varies. These facts indicate that in the process of YBCO thin film by magnetron supttering, Ar ratio in sputtering gas can affect the stoichiometric ratio of elements in the thin film. Ultra high or low Ar ratio can result in the crystal lattice distortion of YBCO thin film, thus deteriorate its superconducting properties.