On the enlargement of active area of superconducting junction radiation detector with segmented absorbers

超导辐射探测器具有优异的能量分辨率，但也存在活动区域小的缺点。在实际应用辐射探测器时，具有较大活动面积的探测器是可行的。为了克服这一缺点，我们开始研究制造具有节段吸收器的普通金属-绝缘体-超导体结探测器（NIS探测器）。由于各节段吸收体的热容较小，使得NIS探测器的能量分辨率保持良好。NIS检测器的有效面积与分段吸收器的面积总和一样大。每个分段吸收器通过超导引线相互连接，具有相同的电势并相互热隔离。具有分段吸收器的NIS检测器申请了专利。首先，我们研制了以Ag为正常金属，Al为氧化后绝缘体，Nb为超导体的磁控溅射装置。然后，对每种材料的溅射条件和氧化条件进行了优化。最后，我们利用X-Y阶段和阴影掩膜来定义探测器膜的图案，制作了NIS探测器。在这些NIS探测器上，我们测量了温度从8K到0.3K的电流-电压（I-V）特性。探测器显示了表征NIS结的I-V曲线。

Superconducting radiation detectors have excellent energy resolution, however, they also have shortcomings : their small active areas. In applying radiation detectors for practice, a detector with a larger active area is plausible. To overcome this disadvantage, we started studying to fabricate normal metal-insulator-superconductor junction detector (NIS detector) with segmented absorbers. With the small heat capacitance of each segmented absorber, the energy resolution of the NIS detector is kept excellent. The active area of the NIS detector is as large as the summed area of segmented absorbers. Each segmented absorber is connected one another by superconducting leads, to have the same electric potential and to isolate thermally each other. A patent is submitted on the NIS detector with segmented absorbers.First, we developed magnetron sputtering device for Ag as normal metal, Al as insulator after oxidation, and Nb as superconductor. Next, the sputtering condition for each material and the oxidation condition were optimized. Finally, we fabricated NIS detectors with exploiting an X-Y stage and a shadow mask to define patterns of membranes of detectors. On these NIS detectors, we measured current-voltage (I-V) characteristics at the temperature from 8K to 0.3K.The detectors showed I-V curves which characterize NIS junctions.