硒蒸气浓度对制备CIGS薄膜的影响

采用“预制层硒化法”制备CuIn_1-xGa_xSe₂ (CIGS)薄膜. 基于自主设计的“双层管式硒化装置”, 通过控制硒蒸气浓度优化退火工艺, 研究硒蒸气浓度对薄膜光电性能的影响. 利用俄歇电子能谱(AES)和X射线衍射分析(XRD)等手段对不同硒浓度氛围下生成的CIGS薄膜的成分和物相进行表征, 并在AM1.5、1000 W·m^-2的标准光照条件下比较相应CIGS电池器件的输出性能. 实验结果表明: 饱和硒蒸气下退火得到的样品, 基底钼膜遭到严重腐蚀破坏, 失去背电极功能; 在低浓度硒气氛下退火不能有效消除CIGS薄膜的偏析和缺陷, 以致光电转换效率低; 而在无硒惰性氛围下退火的样品, 生成了物相均一化的CIGS薄膜, 由此制备的CIGS电池取得了8.5%的转换效率.     

两步法制备CIGS薄膜的工艺研究

本文主要研究了"预制层硒化法"制备铜铟镓硒(CIGS)薄膜的工艺。采用磁控溅射的方式制备In、Cu-Ga金属预制层,然后进行硒化(450℃)以及退火处理(550℃)。SEM结果表明,在室温下溅射沉积In薄膜,并且采用Mo/Cu-Ga/In/Cu-Ga/In的叠层顺序,可以获得平整致密的CIGS薄膜。XRD和SEM测量显示,以单质硒作为硒源,在450℃的硒化之后生成分离的CIS和CGS相,惰性氛围的高温退火可以使分离的CIS和CGS相互融合,形成均一化的CIGS四元化合物。在此基础上,最终完成的CIGS电池光电转换效率为7.5%。     

Successful Nitrogen Doping of 1.3 GHz Single Cell Superconducting Radio-Frequency Cavities

A high intrinsic quality factor(Q_0) of a superconducting radio-frequency cavity is beneficial to reducing the operation costs of superconducting accelerators. Nitrogen doping(N-doping) has been demonstrated as a useful way to improve Q_0 of the superconducting cavity in recent years. N-doping researches with 1.3 GHz single cell cavities are carried out at Peking University and the preliminary results are promising. Our recipe is slightly different from other laboratories. After 250 μm polishing, high pressure rinsing and 3 h high temperature annealing, the cavities are nitrogen doped at 2.7–4.0 Pa for 20 min and then followed by 15 μm electropolishing. Vertical test results show that Q_0 of a 1.3 GHz single cell cavity made of large grain niobium has increased to 4 × 10~(10) at 2.0 K and medium gradient.