倒置生长赝形高效四结太阳电池的辐照损伤行为与机理研究

Due to great requirements for space solar cell/panel with high efficiency and power/mass ration and developed micro-electronics technology, it spurs fast development of multi-junction solar cell using inverted epitaxial technology. Presently, it is getting matured to fabricate some kind of inverted metamorphic III-V group 4-junction solar cells (IMM 4J solar cell). As for the space applications, it is essential in theory and further application to study the space-particle irradiation effects and damage mechanisms of the IMM 4J solar cells. Based on these requirements, we will systematically investigate the electrical degradation behaviors of IMM 4J solar cells under irradiations of electrons and protons, and then explore the equivalent relationships of electrical degradation of IMM 4J solar cell and its InxGa1-xAs sub-cells irradiated by electrons and protons with various energies. In this project, irradiated defects in IMM 4J solar cell and its InxGa1-xAs sub-cells will be also characterized to study their formation, corresponding evolution processes using complementary analytical methods such as spectral response spectra, opto- luminescence spectra, deep level transient spectra and transmission electron microscopy et.al. Thus we could further expose the effects of composition (or band gap) of InxGa1-xAs sub-cell on the irradiated damage behaviors, and determine the main factors of irradiation damage and electrical degradation in the IMM 4J solar cell with complicated compositions and multilayer epitaxial structures. All of the investigated results would become fundamental supports to optimize the structures and procedures for improvement of anti-irradiation damage of IMM 4J solar cells.

高效、轻质空间电源需求及先进微电子制造技术催生了倒置生长赝形多结太阳电池的快速发展，目前倒置式III-V族四结太阳电池（简称IMM四结电池）的制备技术已经基本成熟。作为空间应用，迫切需要深入研究IMM四结太阳电池空间带电粒子辐照效应与损伤机理。本项目基于这一需求，系统研究IMM四结电池及其InxGa1-xAs子电池在空间电子和质子辐照条件下电性能退化规律，探索不同能量电子和质子辐照性能退化的等效关系。利用光谱响应谱、光荧光谱、深能级瞬态谱、透射电子显微镜等分析方法研究IMM四结电池及其InxGa1-xAs子电池中辐照缺陷形成、演化及其对电性能退化的影响规律，揭示InxGa1-xAs子电池成分对电池辐照损伤和性能退化的影响机制，以及在具有复杂组成和多层外延结构的IMM四结电池中决定辐照损伤和性能退化的主要因素，为提高IMM四结电池的抗辐照性能而进一步优化电池组成和结构提供理论依据。

本项目系统研究了IMM四结电池及其InxGa1-xAs子电池中辐照缺陷形成、演化及其对电性能退化的影响规律，揭示InxGa1-xAs子电池成分对电池辐照损伤和性能退化的影响机制，并提出了新型多结电池结构优化与抗辐射设计的基本思路。.结果表明，相对于传统的GaAs（带隙1.42eV）和GaInP（带隙1.8eV）电池，用于四结电池结构中的InxGa1-xAs（带隙约0.7eV和1.0eV）子电池对于带电粒子辐照都较为敏感。其中低能电子（电子能量低于200keV）辐照对InxGa1-xAs子电池的损伤效应小；低能质子（射程能够达到电池功能区时）、高能电子和高能质子辐照时，InxGa1-xAs子电池均产生较大的辐照损伤，电池的电性能会随辐照注量呈对数关系下降，这与常见的III-V族电池的辐照效应类似。InGaAs(1.0eV)子电池的Isc退化率cIsc最大，而InGaAs(0.7eV)子电池的Voc退化率cVoc最大。.基于砷化镓多结电池的辐照效应，利用光谱响应、电池暗特性、光致荧光光谱及时间分辨荧光光谱，揭示出辐照导致电池有源区产生的大量位移缺陷引起有效载流子寿命显著下降，是因其电池性能下降的主要机制，并建立了有效载流子寿命与荧光强度等效模型。研究发现，带隙1.0eV 和0.7eV子电池的本征载流子浓度的高低也会对辐照电池性能退化行为产生影响。.III-V族多结电池的研究表明，IMM多结电池在1MeV电子辐照条件下，电性能退化与辐照注量仍呈对数关系，且发现多结电池中带隙为1.0eV子电池辐照损伤率最大，但是带隙为0.7eV电池由于原始短路电流最小而成为四结电池性能退化的控制部分。本项目还研究了多结电池耦合效应、辐照损伤不均匀性及其影响，揭示了多结电池间荧光耦合效应、并联电阻耦合效应的基本机制，建立了不均匀辐照损伤和耦合效应模型。在此基础上，提出了四结电池基于光谱等效的结构优化方法和基于荧光耦合效应与辐射损伤机制的抗辐射优化设计方法。