Study of Theoretical Investigation of Bipolar Effect in 4H-SiC VJFET

In the present work, forward characteristics of normally-off 4H-SiC VJFET are simulated using commercial Sentaurus TCAD simulator. In the forward characteristics, the effect of channel concentration is analyzed to investigate the normally-off behavior and the device exhibits positive threshold voltage. At VGS = 3 V, due to injection of significant holes in the channel, a large drain current is observed which shows bipolar mode in the device. In addition, it is also observed that at low doping concentration i.e. 1×1015 cm-3 the increase in IDS is 79% as VGS increase from 2.9 to 3.0 V. But this increase in IDS reduces with increase in channel doping and it becomes 56% at channel doping of 9×1015 cm-3. The influence of bipolar effect on current gain and specific on resistance is also discussed in this paper.