Degradation behaviors of electrical properties of GaInP/GaAs/Ge solar cells under <200 keV proton irradiation

The degradation effects of the GaInP/GaAs/Ge triple-junction solar cells irradiated by <200 keV protons are investigated on the basis of the spectral response analysis and measurements of electric property. The experimental results show that with increasing proton fluence I_sc, V_oc and P_max decrease obviously. The proton energy exhibits an important influence on the degradation effects of the triple-junction cells dependent on the proton penetration range in the cells. As the proton energy is lower than 100 keV, irradiation-induced damage occurs in the top cell, while the irradiation with proton energy higher than 100 keV causes damage mainly in the middle sub-cells. Comparing the changes in the electrical properties of the triple-junction cells, a conclusion can be made that the GaAs middle sub-cell plays a major role in leading to more severe degradation. In this case, the 170 keV protons are suggested to be used to evaluate the performance of the GaAs triple-junction solar cells, for they can produce more severe degradation effects. Crown