空间用倒装三结太阳能电池及其抗辐射性能研究

使用金属有机化学气相沉积技术,在4英寸GaAs衬底上获得了空间用GaInP/GaAs/In_(0.3)Ga_(0.7)As倒装三结太阳能电池.高分辨X射线衍射和阴极射线发光测试结果表明AlInGaAs应力渐变缓冲层的晶格弛豫度约100%,其整面平均穿透位错密度约5.4×10~6/cm~2.与GaInP/InGaAs/Ge常规三结太阳能电池相比,在AM0光谱、25℃测试条件下,面积24 cm~2的倒装三结太阳能电池转换效率达到32%,输出功率提高了5%.采用1 MeV高能电子对倒装三结电池进行粒子辐照测试,电池各项性能参数随不同辐照剂量发生改变,在1×10~(15)/cm~2辐照总剂量下电池转换效率衰降比例达到15%.

Inverted metamorphic triple-junction solar cell and its radiation hardness for space applications

In recent years, with the development of solar cell technology, the conversion efficiency of the lattice-matched Ga_0.51In_0.49P/In_0.01Ga_0.99As/Ge triple-junction solar cell has achieved 30% under AM0 spectrum. As is well known, it is difficult to further improve the efficiency due to the limited bandgap combination. Therefore, an inverted metamorphic triple-junction solar cell is designed by replacing the Ge subcell with a 1.0 eV InGaAs subcell. The efficiency could be increased with the open-circuit voltage increasing, while the short circuit current maintains a similar value.#br#In this paper, the inverted metamorphic GaInP/GaAs/In_0.3Ga_0.7As triple-junction solar cells are grown on 4-inch GaAs substrates via metal organic chemical vapor deposition. Optimizing the epitaxy process, AlInGaAs graded buffer shows nearly 100% relaxation by the reciprocal space mapping of the high-resolution X-ray diffraction and low average threading dislocation density~5.4×10⁶/cm² evaluated from the cathodoluminescence image. Finally, the inverted metamorphic triple-junction solar cell with 24 cm² area shows a conversion efficiency of 32% with an open-circuit voltage of 3.045 V and a short-circuit current of 404.5 mA under one sun, AM0 spectrum, 25℃ conditions, which is 5% higher than the lattice-matched GaInP/InGaAs/Ge triple-junction solar cell. Under 1 MeV electron irradiation test, the degradations of the external quantum efficiency and I-V characteristics of inverted metamorphic triple-junction solar cell are exhibited each as a function of fluence, and finally the end-of-life efficiency is 27.2% with a degradation of 15% under 1×10¹⁵/cm² fluence. More experiments mainly focusing on the lattice quality of AlInGaAs graded buffer and the structure of In_0.3Ga_0.7As subcell, will be carried out to improve the efficiency and enhance the radiation hardness.