BIFACIAL SILICON SOLAR CELL DEGRADATION DUE TO LOW ENERGY PROTON BOMBARDMENT:EXPERIMENTAL AND MODELING

摘要

Laboratory experiments of 0.5 MeV proton irradiation of the back of bifacial silicon solar cells with n+-p-p+ structure were undertaken for the first time. Front and preferentially back internal quantum efficiency data were used as a tool for cell radiation damage analysis. A non uniform defect distribution vs depth was taken into account for determining the recombination parameters of irradiated cells. Analysis of experimental data demonstrates independence of damage coefficient on proton energy, E, when E<0.46 MeV. These results are in agreement with the model describing the effect of proton irradiation on recombination in Si by introducing defects of two types – point defects and disordered regions. Thelatter defects decrease their dominating contribution in recombination processes with proton energy decreasing when below ～ 0.8 MeV. The model and experimental diffusion length damage coefficients are useful for predicting cell degradation in a space radiation environment. The model can also be used for analysis of solar cells with defect layers introduced by technology processing.