A performance comparison of normally-off and normally-on SiC JFETs toward use in high-temperature power modules

The high-temperature static and dynamic characteristics of the new 1200 V, 45 mΩ, 9 mm2 depletion-mode SiC vertical trench junction field-effect transistor (vtJFET) are compared with those of a 1200 V, 50 mΩ, 9 mm2 enhancement-mode SiC vtJFET. It is shown that both devices are fully capable of high-temperature operation and that each type has its own unique advantages. For applications operating in extreme high-temperature environments, the larger saturation current (~2.5x) and lower on-state resistance (~150 mΩ at 250 °C) of the depletion-mode SiC vtJFET provide very attractive performance at temperatures beyond silicon's fundamental limitations. In addition, operating the normally-on vtJFET at VGS less than 2 V reduces the gate drive's current requirements to a negligible level, which is an important design factor for high-temperature power modules that use multiple die in parallel.