2.5 kV/100 A high-power P-i-N diode was electron, proton and helium irradiated in a wide range of irradiation doses with irradiation energies in the MeV range. The resulting forward I-V curves were registered in the temperature range 30-125 o C to investigate the magnitude of the crossing point current of the I-V curves--I X I N G . I X I N G was found to decrease with increasing irradiation dose and to disappear at high doses for all three irradiation treatments with exception of ion irradiated diodes with defect peaks placed deeply into the anode region. Using a simple model based on the thermal and injection dependence of the carrier lifetime, the explanation of this effect is presented with the support of the non-isothermal 2-D device simulation of helium irradiated devices.