Stability and performance analysis of a SiC-based cascode switch and an alternative solution

Wide band-gap semiconductors are most attractive as materials for power devices due to low losses, improved temperature capability and high thermal conductivity. Although silicon carbide Schottky diodes have been commercially available on the market for years, an active wide band-gap switch is still missing. Probably the best performance of upcoming devices is gained with normally-on concepts such as silicon-carbide JFETs and gallium-nitride HEMTs. However, the vast majority of power electronic topologies rely on normally-off switches. An alternative approach is the use of the cascode concept which combines a normally-on wide band-gap device with high blocking capability and a low-voltage normally-off silicon MOSFET. In this work, the performance and stability of such an arrangement is analyzed and an alternative solution is proposed.