Simulating the Radiation Response of GaAs Solar Cells Using a Defect-Based TCAD Model

Three-dimensional TCAD simulations are used for physics-based prediction of space radiation effects in III-V solar cells, and compared with experimentally measured characteristics of a p⁺ n GaAs solar cell with AlGaAs window. Dark and illuminated I-V curves as well as corresponding performance parameters are computed and compared with experimental data for 2 MeV proton irradiation at various fluences. We analyze the role of majority and minority carrier traps in the solar cell performance degradation. The traps/defects parameters used in the simulations, for n-type and p-type GaAs, are derived from Deep Level Transient Spectroscopy (DLTS) data. The physics-based models allow a good match between simulation results and experimental data. However, assuming the device performance is dominated by a single recombination center is not adequate to completely capture the degradation mechanisms controlling the photovoltaic performance.