Analysis on degradation characteristics of component subcells in IMM triple-junction solar cells

The radiation response of single-junction solar cells with InGaP, GaAs and InGaAs with different indium content (20 and 30%), were prepared and irradiated with varieties of energies of protons and electrons. These cells are component subcells of inverted metamorphic triple-junction (IMM3J) solar cells. Characteristics of the solar cells, namely, light-illuminated current-voltage (LIV) and external quantum efficiency (EQE) were obtained before and after irradiation, and the corresponding changes due to the irradiations were compared and analyzed. The degradation of the cell output parameters by electrons and protons were plotted as a function of the displacement damage dose. It was realized that the radiation resistance of the two InGaAs cells is reasonably equivalent to that of the InGaP and GaAs cells from the materials standpoint. However, the InGaAs cells show relatively low radiation resistance to electrons especially for short-circuit current.