Modelling voltage dependence of photocurrent in proton irradiated GaAs cells

GaAs single junction cells were irradiated with high doses of protons and current-voltage characteristics were obtained under AM0 illumination. A discrepancy between the measured photocurrent and the typically constant photocurrent of a solar cell was determined. The measured photocurrent showed a voltage dependence. We attribute the voltage dependence of the photocurrent to a combination of low diffusion length and the voltage dependence of the width of the space charge region. A model is developed which predicts the photocurrent of the cells correctly.