Damage mechanisms in radiation-tolerant amorphous silicon solar cells

The relative importance of ionization and displacement damage effects in irradiated amorphous silicon (a-Si) solar cells is demonstrated. Degradation of these devices by particles representative of a space radiation environment is dominated by ionizing radiation effects and not by displacement damage. Degradation of a-Si cells correlates with the ionizing dose deposited in device active regions for most of the cases examined. Specific dose deposition conditions are identified for which displacement damage effects evidently are important. Radiation-induced degradation of a-Si cells is demonstrated to anneal at temperatures much lower than for conventional crystalline solar cells. It is predicted that if these devices are operated in a space radiation environment at 70°C, annealing during irradiation will result in an end-of-life efficiency that is very near the beginning-of-life value. Thus, low-cost a-Si solar cells are attractive for space power applications in harsh radiation environments