VTH & Gm, max Instability Analysis of the Multiple GaN Chips based Cascode Power Module

In this work, we present developed and tested a multiple-GaN-chips based cascode power module to scale up the power ratings. This cascode power module consists of two switching elements that connect multi-GaN-chips of AlGaN/GaN-on-Si HEMT cells with low voltage Si MOSFETs in series. As an electrical characterizations, static output and transfer characteristics of the module were tested at room temperature and with reverse-leakage characteristics, the constructed cascode power module has a blocking voltage of more than 550 V. Following electrical characteristics, we present an extensive study of threshold voltage (V
TH
) and transconductance instability (G
m, max
) of the cascode power module under positive and negative gate bias temperature instability experiments. The trapping and de-trapping of electrons from pre-existing oxide traps lead the power module to negative and positive V
TH
instabilities and G
m, max
degradations. These findings on performance and instability open the path for a better understanding of enhancements and failure causes, which will help to accelerate the growth of emerging GaN cascode technologies.