The changes in the electrical properties of 4H-SiC epitaxial layer induced by irradiation with 7.0 MeV C+ ions were investigated by current-voltage measurements and deep level transient spectroscopy (DLTS). Current-voltage characteristics of the diodes fabricated from epilayers doped with different nitrogen concentrations were monitored before and after irradiation in the fluence range of 109–1010 cm−2. The leakage current was not changed after irradiation, while the forward current-voltage characteristics of the diodes showed an increase in the series resistance, which is mainly related to the high degree of compensation occurring near the end of the ion implant depth.The temperature dependence of the carrier mobility determined from the I-V measurements in the temperature range of 100–700 K shows a T−3 dependence of mobility as determined from the nonirradiated as well as the irradiated diodes. DLTS …