Recovery at room temperature annealing on 4H–SiC SBDs by gamma irradiation

Abstract

The impact of gamma irradiation and subsequent recovery at room temperature on the device performance of commercial 4H–SiC Schottky barrier diodes (SBDs) was investigated through the analysis of the electrical properties and the deep level transient spectroscopy (DLTS). The ideality factor (n) of the SBDs increased from 1.01 to 1.13 with an increasing irradiation dose, but recovered after 7 days of room temperature annealing. To determine Schottky barrier heights (ΦB), both current-voltage (I–V) and capacitance-voltage (C–V) measurements were performed. The results of the combined I–V and C–V analysis showed that a little variations in ΦB were consistent with the variations in irradiation dose, except for the ΦB calculated by C–V measurement at 30 kGy. Similarly, the ΦB recovered after 7 days at room temperature. DLTS analysis revealed the presence of Z1/Z2 traps in the samples after 7 days at room temperature annealing. These traps exhibited activation energies ranging from 0.46 eV to 0.55 eV. The trap concentration (NT) increased from 9.48 × 1012 cm−3 to 2.23 × 1013 cm−3 with the increasing irradiation dose. These findings indicate that gamma irradiation-induced point defects were the primary cause of the degradation of 4H–SiC SBDs.