Effects of proton radiation on field limiting ring edge terminations in 4H–SiC junction barrier Schottky diodes

In this study, the effects of high-energy proton radiation on the effectiveness of edge terminations using field limiting rings (FLRs) in 4H–SiC junction barrier Schottky (JBS) diodes were examined in detail. The devices were irradiated using 5-MeV protons at fluences ranging from 5×1012 cm−2 to 5×1014 cm−2. Further, the reverse breakdown performances of the investigated devices were measured both before and after irradiation. Proton irradiation initially decreased the breakdown voltage (BV); subsequently, the BV was increased as the proton fluence increased. At a fluence of 5×1013 cm−2, the BV was reduced by approximately 18%, whereas it was reduced by approximately 5% at a higher proton fluence of 5×1014 cm−2. The related degradation mechanism that was associated with this phenomenon was also investigated using the numerical simulations of the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the device. The main contribution to the radiation-induced changes in BV originates from the variations of charge distribution at the SiO2/4H–SiC interface and the reduction of the net carrier density in the drift region. Both the aforementioned variations affect the spread of the electric field in the FLR edge termination regions.