Analysis and modeling of non-uniform displacement damage in GaAs laser power converters under 500 keV proton irradiation

Laser wireless power transmission (LWPT) technology offers broad prospects for space applications. However, high-efficiency GaAs laser power converters (LPCs), as the key enabling devices, are susceptible to irradiation by charged particles during on-orbit operation, with non-uniform displacement damage induced by low-energy protons representing a critical factor. In this study, 500 keV proton irradiation experiments and modeling were performed on GaAs single-, dual-, and quadruple-junction LPCs. The results demonstrate that protons generate a higher average displacement defect introduction rate in the bottom cells, which consequently exhibits a larger external quantum efficiency (EQE) degradation. To reveal this behavior, an irradiation-induced degradation model for GaAs MJLPCs was established, incorporating the non-uniform distribution of displacement defects by 500 keV proton irradiation. The proposed model shows consistency with the measured EQE data and indicates that the electrical degradation is primarily attributed to the reduction of minority-carrier number in the base region of the bottom cells.