粒子辐射GaAs太阳电池引起性能衰降的少数载流子俘获中心的检测鉴别

To improve the radiation resistance of GaAs space solar cells，and to research and develop new space solar cells, it is essential to investigate the irradiation-induced defects in GaAs solar cells induced by proton and electron irradiation, and to detect and distinguish the minority carrier capture centers related to the ion irradiation induced degradation of GaAs solar cells with the change of material, structure, technology, and doping. The proton and electron irradiation-induced defects produced in GaAs space solar cells will be investigated with photoluminescence (PL), electroluminescence (EL), and deep level transient spectroscopy (DLTS) measurements. The research work aims to identify the minority carrier capture centers in the irradiated GaAs solar cells among all irradiation-induced defects induced by proton and electron irradiation and recognize the causes of the irradiation-induced degradation of GaAs solar cells through the irradiation-induced degradation of GaAs solar cells related to the k and σ of the minority carrier capture center. The research results will give a support to new solar cell designed, and will provide the information for irradiation resisting design and performance improving of new solar cell, which will be potentially applied to understand the causes of the proton and electron irradiation-induced degradation of the GaAs/Ge solar cells and improve the irradiation tolerance of the solar cells in space radiation application.

更长寿命新太阳电池的设计研发及其抗辐射性能的提高，需要细致研究电池材料、结构、制备工艺和外延层区掺杂等变化时，质子、电子等粒子辐射GaAs太阳电池产生的缺陷种类及结构、缺陷能级及其俘获载流子特性，检测和鉴别出与电池性能衰降相关的少数载流子俘获中心。为此本课题拟结合变温光致发光光谱(PL)、电致发光光谱(EL)和光激发深能级瞬态谱(DLTS)等测试方法，分析质子、电子辐射空间GaAs太阳电池产生的辐射损伤缺陷，研究确定各种辐射损伤缺陷中少数载流子俘获中心，探索太阳电池性能衰降变化与少数载流子俘获中心引入率k及俘获截面σ等物理参数之间的本质联系，用k和σ分析电池性能衰降，探索太阳电池辐射损伤的微观机理，为更长寿命太阳电池设计研发及抗辐射加固筛选提供科学依据。

项目研究了质子、电子等粒子辐射GaAs太阳电池产生的缺陷种类及结构、缺陷能级及其俘获载流子特性，检测和鉴别出与电池性能衰降相关的少数载流子俘获中心，为更长寿命新太阳电池的设计及其抗辐射加固筛选提供了科学依据。利用变温光致发光光谱(PL)、电致发光光谱(EL)等测试方法，分析质子、电子辐射空间GaAs太阳电池产生的辐射损伤缺陷，研究确定各种辐射损伤缺陷中少数载流子俘获中心，探索太阳电池性能衰降变化及辐射损伤的微观机理。取得重要研究成果有:随注量增加三结太阳电池的电流限制子电池从顶电池转变为中间电池，在同一注量下的中间电池对三结太阳电池整体的开路电压降的贡献更大；发现无论是单结太阳电池，还是三结电池 GaInP顶电池和GaAs中间电池的少数载流子寿命的减小幅度随着电子注量的增加而增大，三结电池的中间电池的少子寿命损伤系数比顶电池的大两个数量级，表明中间电池的抗辐照性能劣于顶电池；鉴别出电子辐照引入GaAs中间电池的非辐射复合中心为E5电子陷阱，位于Ec - 0.96 eV处，引入GaInP顶电池的非辐射复合中心为H2空穴陷阱，位于Ev + 0.55 eV处；反淬灭现象首次在辐照以后的GaInP材料中被观测，与材料中的中间态能级有关，根据PL淬灭-反淬灭理论分析得到引起PL反淬灭现象的中间态的热激活能，得到引起PL热淬灭的非辐射复合中心有两个，分别为位于Ev + 0.55 eV处的H2空穴陷阱和位于Ev + 0.76 eV处的H3空穴陷阱，而引起PL反淬灭的中间态能级对应于0.18 eV。这些研究成果为更长寿命太阳电池设计研发及抗辐射加固筛选提供了科学依据。