In the present work the effect of irradiation with 8-MeV protons at doses (D) in the range 1.10(14) - 1.10(16) cm(-2) on p-n structures and Schottky diodes based on epitaxial 6H and 4H SiC layers was studied. Commercial (CREE) samples and samples fabricated by sublimation epitaxy (SE) in our laboratory were used. Parameters and concentrations of deep centres (DC) were determined by transient capacitance and current spectroscopy. It was shown that proton irradiation may lead to an increase in the initial doping level of 6H-SiC samples. The obtained results are analysed and the properties of radiation-induced defects are discussed.