Anomalous effects in silicon solar cell irradiated by 1-MeV protons

Abstract

Several silicon solar cells having thicknesses of approximately 63 μm, with and without back-surface fields (BSF), were irradiated with 1-MeV protons having fluences between 1010 and 1012 protons/cm2. The irradiations were performed using both normal and isotropic incidence on the rear surfaces of the cells. It was observed that after irradiation with fluences greater than 1011 protons/cm2, all BSF cells degraded at a faster rate than cells without BSF. The irradiation results are analyzed using a model in which irradiation-induced defects in the BSF region are taken into account. A number of other possibilities for BSF cell degradation are considered. Tentatively, it is concluded that an increase in defect density due to the formation of aluminum and proton complexes in BSF cells is responsible for the higher-power loss in the BSF cells compared to the non-BSF cells.