Analysis of cyclic spontaneous switchings in GaN & SiC cascodes by snappy turn-off currents

Abstract

This paper investigates the crosstalk-induced spontaneous switchings as continuous cycles of turn-on and turn-off transients as a key reliability criterion in SiC and GaN cascode power devices. The paper presents a wide range of measurements to describe the severity of unwanted switching cycles in presence of a few diodes with high turn-off dI/dt which results in a negative gate voltage induced by the source inductance. Modelling is performed which confirms the theory described to explain the root cause of the continued oscillatory transients and comparisons are made with standalone SiC power MOSFETs.