Threshold voltage instability and hysteresis in gamma-rays irradiated 4H-SiC junction field effect transistors

High dose irradiation effects of gamma-rays up to 17 MGy (H2O) on 4H-SiC junction field effect transistors (JFETs) were investigated. Due to the irradiation, gradual positive threshold voltage (V-th) shift as high as 0.5 V and continuous decrease in transconductance g(m) were observed. In addition, V-th instability and hysteresis appeared for the irradiated JFETs when the gate voltage (V-G) sweep direction, sweep interval, i.e., averaged sweeping rate, sweep range, and delay time were changed. Increase of V-G interval attributed to positive V-th shift for both forward and reverse directions, whereas narrowing of sweep range and increase of delay time resulting in a more noticeable negative shift of V-th for the reverse direction. Such V-th hysteresis indicates that capture and release of carriers predominantly took place via hole traps formed around the gate region due to high dose gamma-ray irradiation. Published under an exclusive license by AIP Publishing.