Variation of the properties of 4H-SiC radiation detectors upon irradiation by 24 GeV protons

We had investigated effects of the high-energy proton irradiation on the properties of radiation detectors fabricated as Schottky diodes on 4H-SiC. The doses of 24 GeV protons ranged from 1013 cm-2 up to 1016 cm-2. Numbers and activities of radionuclides and isotopes produced after the irradiation were analysed. Activities of 7Be and 22Na were found to be proportional to the irradiation dose and ranged from 1.3 up to 890 Bq and from 1.9 up to 950 Bq, respectively. The contact properties were investigated by means of the current-voltage analysis. At lower irradiation doses a slight decrease of the effective potential barrier height from about 0.75 eV down to < 0.7 eV took place. The reverse current of the diodes grew by up to one order of magnitude. At the doses above 3x1015 cm-2 opposite changes were observed. Irradiation by up to 1x1016 protons/cm-2, resulted in the increase of the potential barrier height up to ~ 0.85 eV, followed by the drop of the reverse current by up to two orders of magnitude. The observed effects were explained by the appearance of the disordered material structure because of the high-energy particle bombardment.