Analysis of parameters determining nominal dynamic performance of 1.2 kV SiC power MOSFETs

A good understanding of internal MOSFET capacitances is required in order to accurately model the dynamic characteristics of SiC MOSFETs. MOSFET compact models used to simulate and optimize power converter systems have to take into account the effects of non-linear voltage-dependent internal MOSFET capacitances correctly. In this paper, the individual influence of the voltage-dependent drain-source capacitance Cds and the drain-gate capacitance Cdg on the MOSFET dynamics is investigated in detail. A comprehensive analysis of the switching performance of 1.2 kV SiC power MOSFETs with respect to Cds and Cdg by means of a physics-based compact model, TCAD modeling, and the switching measurements of a 1.2 kV 80 mO SiC power MOSFET is presented. It is demonstrated that the non-linearity of Cgd impacts the turn-off delay time td, OFF, while the non-linearity of Cds does not have a significant impact on the switching transients.