Design and Gate Drive Considerations for Epitaxial 1.2 kV Buried Grid N-on and N-off JFETs for Operation at 250°C
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.
Anton J. Bauer, Peter Friedrichs, Michael Krieger, Gerhard Pensl, Roland Rupp and Thomas Seyller
J. K. Lim et al., "Design and Gate Drive Considerations for Epitaxial 1.2 kV Buried Grid N-on and N-off JFETs for Operation at 250°C", Materials Science Forum, Vols. 645-648, pp. 961-964, 2010