约瑟夫森结Nb电极的实验研究

通过溅射Nb膜张力与氩（Ar）压强的关系，超导转变温度Tc，室温阻扰与液氮温度阻抗比RRT／RLN2，沉积中Ar浓度CAr与负偏压关系的测量和扫描电子显微镜的观察分析，对约瑟夫森结Nb电极作了研究。发现Ar压强在1．1Pa时，Nb膜呈现无应力状态；低负偏压下沉积的Nb膜晶粒结构是由致密膜到圆柱状。在偏压Ub＝－50V时，获得表面致密均匀、晶粒结构合适的Nb膜。对Nb膜用阳极氧化电压谱图（AVS）分析，证实沉积的Nb膜内不存在氧化物、寄生结和分层界面。

Experimental Investigation of the Nb Electrode for the Josephson Junction

We have studied the Nb electrode for the Josephson junction by measuring dependence of sputtered Nb fi1m stress on Ar pressure,transition temperature,resistance ration(RRT/RLN2 )and Ar concentration in sputtering deposition on negative bias voltage. We have found that zero stress occures at 1. 1 Pa and that the Nb film grain structure form a compact film at low negative bias voltage to columnar and that the Nb film with the finest grain structure and smoothest surface is obtained at a bias voltage Ub= - 50 V.By analysing anodisation voltage spectroscopy (AVS),we have confirmed that the oxide, parasitical junction and interfaces of separate layers do not exist in Nb films deposited.