The 1.2 kV 4H-SiC buried-grid vertical JFET structures with Normally-on (N-on) and
Normally-off (N-off) design were investigated by simulations. The conduction and switching
properties were determined in the temperature range from -50°C to 250°C. In this paper, the
characteristics of the N-on designs with threshold voltage (Vth) of -50 V and -10 V are compared
with the N-off design (Vth=0). The presented data are for devices with the same channel length at
250°C. The results show that the on-resistance (Ron) decreases with increasing channel doping
concentration and decreasing channel width. The presented turn-on, Eon, and turn-off, Eoff, energies
per pulse are calculated under the switching conditions 100 A/cm2 and 600 V with a gate resistance
of Rg=1 . For the two N-on designs the total switching losses, Esw=Eon+Eoff, differ less than 30%
with Wch 0.7 m. With Wch=0.5 m the switching losses of N-off design are almost one order of
magnitude higher than those of the N-on design with Vth = -50 V.
