Radiation damage in silicon solar cells from low-energy protons

Recent evidence has indicated that kilovolt-energy protons are a probable cause for solar-cell array degradation in synchronous-orbit satellites. This damage can occur in the small areas of the cell that have been unprotected by the coverslip. This paper reports on solar-cell current degradation at fixed voltages in nominal 10-Ω.cm silicon solar cells with coverslips which are irradiated by 150- and 270-keV protons. The damage, which is shown to be dependent on exposed area and proton energy, can be minimized by putting adhesive on uncovered cell areas or by reducing the open area with close-fitting coverslips.