In this work we have focused on characterization of the surface barrier detectors on high quality 4H-SiC epitaxial layer. The thickness of the layer was 70 mu m and the diameter of circular Au/Ni Schottky contact was 2 mm. The forward and the reverse current-voltage characteristics of fabricated diode structures were measured. From the forward characteristics the Schottky barrier height, ideality factor and series resistance were calculated and from reverse characteristics the operational voltage of detectors was determined. The spectrometric performance of selected detector structures were tested using various sources of radiation like Pu-238, Ra-226 (a-particles) and Am-241 (X-and gamma-rays) and showed the high energy resolution. Detector structures were irradiated with 165 MeV Xe-132(23+) ions and 5 MeV electrons up to a fluency of 1.5 x 10(10) cm(-2) and 1.1 x 10(14) cm(-2), respectively. The degradation of the spectrometric performance was observed and evaluated.