Analysis of Current Capability of SiC Power MOSFETs Under Avalanche Conditions

The phenomenon of reduced energy capability of power metal-oxide-semiconductor field-effect transistors (MOSFETs) at high avalanche currents is investigated in commercial 1.2-kV 4H-SiC MOSFETs. Unclamped inductive switching (UIS) measurements as well as electrical transport simulations are used to identify the current paths and maximum avalanche currents, providing insight into the design limits. The investigated devices show a reduced energy capability for avalanche current above 52 A due to the latching of the parasitic bipolar junction transistor (BJT). The BJT also limits the maximum switchable current to ≤102 A. Based on the measurements and simulations, a procedure utilizing UIS measurements for identification of design limits is presented.