Effects of proton irradiation on the photoelectronic properties of microcrystalline silicon

Abstract We report on proton irradiation of microcrystalline silicon with 2 MeV protons and find a drop in the mobility–lifetime product related to an increase in the density of gap states as revealed by modulated photocurrent experiments. The dark conductivity also drops due to a shift in the Fermi energy by defect creation and re-balance of charge. The impact on the ambipolar diffusion length, representing the minority-carrier properties, is much smaller. The electronic properties of P and B doped samples are hardly affected. We discuss the implications for microcrystalline silicon pin solar cells.