Abstract
GaAs single junction cells, representative of the middle cell in triple junction Ga0.5In0.5P/GaAs/Ge cells, were irradiated with various fluences of 1- and 3-MeV electrons as well as 1-MeV protons. The light I-V curves measured at room temperature exhibit a voltage-dependent photocurrent. The photocurrent is modeled taking into account the voltage-dependent width of the space charge region in combination with a strongly decreased minority carrier diffusion length. By extracting the width of the space charge region from capacitance measurements and the base layer diffusion length from the external quantum efficiency of the cell, the experimental behavior is reproduced accurately.