We have characterised the deep level defects present before and after annealing the proton-irradiated Ni/nitrogen-doped 4H-SiC Schottky barrier diodes (SBDs) using deep level transient spectroscopy. The bombardment of the sample was carried out at a fluence of 1.0 × 1012 cm−2. The quality of the Ni/4H-SiC SBDs was evaluated before and after proton irradiation and annealing by current–voltage (I-V) and capacitance–voltage (C-V) measurements, carried out at room temperature (300 K). The I-V and C-V results revealed extensive degradation of the diodes properties after proton irradiation at the aforementioned fluence. Rectification properties of the Ni/4H-SiC SBDs recovered gradually after annealing in flowing argon at temperatures varying from 125 to 625 °C. The presence of four electron traps (Ec – 0.10, Ec – 0.13, Ec – 0.18 and Ec – 0.69 eV) was observed in as-grown Ni/4H-SiC SBDs. Deep level defects, Ec – 0.42 and Ec – 0.76 eV, were revealed after annealing the proton-irradiated SBDs up to 225 °C. The two defects observed at 225 °C later annealed out at 425 °C, causing a significant change in the spectrum. The annealing out of Ec – 0.42 and Ec – 0.76 eV at 425 °C was concurrent with detection of two electron traps, Ec – 0.31 and Ec – 0.62 eV. We speculate that the defects Ec – 0.42 and Ec – 0.76 eV have a link or relationship with defects Ec – 0.31 and Ec – 0.62 eV, respectively. The defect, Ec – 0.31 eV, was stable up to high-temperature annealing and was attributed to a carbon interstitial.
