The 1-MeV electron irradiation effect and damage mechanism analysis of GaInP/GaAs heterojunction solar cells

This study explore the radiation damage effects on GaInP/GaAs heterojunction (HJT) solar cells when subjected to 1-MeV electron irradiation. Light I–V measurements show that V_oc, J_sc, and P_max of the cells exhibit a logarithmic degradation pattern with increasing electron irradiation fluence. Under identical irradiation conditions, the degradation of J_sc is substantially less pronounced than that of V_oc. Under the same conditions, the heterojunction cell shows better radiation resistance, mainly as its V_oc degradation rate with fluence increase is lower than the homojunction cell. Spectral response analysis reveals that 1-MeV electron radiation mainly causes longwave zone damage in the GaInP/GaAs HJT cells, which intensifies as irradiation fluence accumulates. Dark characteristic analysis indicates that both recombination and diffusion currents in the cells rise with increasing irradiation fluence, with recombination current dominating the dark current. Deep level transient spectroscopy tests show that 1-MeV electron irradiation introduces four defects (H₁–H₄) in the cells, located at H₁ (E_v + 0.717 eV)/(Formula presented) (Formula presented) (E_v + 0.744 eV), H₂ (E_v + 0.369 eV), H₃ (E_v + 0.282 eV), and H₄ (E_v + 0.032 eV). Among these, the concentration H₁ of defects increases most drastically with fluence and directly correlates with the rapid degradation of cell performance under high fluence, making it the crucial factor responsible for the swift degradation of GaInP/GaAs HJT cells under high fluence 1-MeV electron irradiation.