Switching Performance of Epitaxially Grown Normally-Off 4H-SiC JFET

Abstract

Static and dynamic behavior of the epitaxially grown dual gate trench 4H-SiC junction field effect transistor (JFET) is investigated. Typical on-state resistance Ron was 6 – 10mΩcm2 at VGS = 2.5V and the breakdown voltage between the range of 1.5 – 1.8kV was realized at VGS = −5V for normally-off like JFETs. It was found that the turn-on energy delivers the biggest part of the switching losses. The dependence of switching losses from gate resistor is nearly linear, suggesting that changing the gate resistor, a way similar to Si-IGBT technology, can easily control di/dt and dv/dt. Turn-on losses at 200°C are lower compared to those at 25°C, which indicates the influence of the high internal p-type gate layer resistance. Inductive switching numerical analysis suggested the strong influence of channel doping conditions on the turn-on switching performance. The fast switching normally-off JFET devices require heavily doped narrow JFET channel design.