GdBaCuO超导薄膜Tc值的优化实验研究

用倒筒式直流磁控溅射装置在LaAlO₃单晶基片上原位沉积了GdBaCuO（GBCO）薄膜．系统调查了GBCO薄膜的超导性质与溅射温度T_s、溅射压力和靶组成的变化规律，发现在720—820℃较宽的基片温度范围、在较低的溅射气压（40Pa）、较高的溅射速率（0.03nm/s）下均可制备出T_c0＞92K，（005）峰摇摆曲线半高宽不大于0.2、膜面非常光滑且具有良好外延特性的c轴嵌镶单晶薄膜．在最佳条件下（T_s=820℃，气 关键词：

OPTIMIZATION OF Tc IN EPITAXIAL GdBaCuO SUPERCONDUCTING THIN FILM BY INVERTED CYLINDRICAL SPUTTERING

Thin films of GdBaCuO(GBCO) compound have been deposited in situ onto LaAlO₃ single crystal substrates by inverted cylindrical sputtering.The variation of superconductive properties of the thin films with the substrate temperature and sputtering pressure has been systematic investigated.By the optimization of deposition parameter,high quality c-axis epitaxial GBCO thin films of T_c0>92K were reproducibly grown at the substrate temperature of 720—820℃ with a low deposition total pressure (40Pa).The T_c0 of the best sample is as high as 93.2K.Only by changing the target composition into GdBa₂Cu₄O_y (Gd₁₂₄),was it observed that the samples always contain some a-axis oriented films,impling that excess copper would favour a-axis growth in thin films,and the T_c of the samples is lower than that with Gd₁₂₃ target.The superconductivity of the thin films under high substrate temperature was clearly improved by the procedure of special post oxygenization at 400℃ in ozone atmosphere.These results are very useful to further prepare large area thin films of GBCO.