Diffusion length variation in 0.5 and 3 MeV proton irradiated heteroepitaxial indium phosphide solar cells

The authors report on the effect of 0.5 and 3.0 MeV proton irradiation on the base diffusion length of InP cells grown on GaAs substrates with In_xGa_1-xAs graded intermediate layers (C. J. Keavney et al., 1991). The cell efficiency changes due 0.5 and 3 MeV proton irradiations have been explained by the variation of the base diffusion length. The 0.5 MeV protons influence the cell performance more strongly than the 3 MeV protons. Computer simulations were used to determine the variation of the base diffusion length with proton fluence for both the energies. The diffusion length damage coefficient (K_L) has been calculated and is constant with fluence. The damage coefficient for 0.5 MeV protons is an order of magnitude higher than for 3 MeV protons. The effect of carrier removal has been considered in the calculations