Investigation on Premature Breakdown Mechanisms in AlGaN/GaN HEMTs by TCAD simulations

Premature breakdown of GaN HEMTs is a common phenomenon which limits their application for power switching. However, the breakdown mechanisms are rarely discussed before. In this paper, we investigate critical factors for dominant breakdown mechanisms in AlGaN/GaN HEMTs by TCAD simulation and give a clear picture of different mechanisms depending on these factors. Three leakage paths at off state are revealed in this paper. Expanding the device size makes no sense for improving breakdown voltage in specific conditions. Reducing UID concentration and improving the quality of GaN buffer is critical.