Temperature Nonmonotonic Behavior of GaN HEMTs Kink Effect Caused by Trap-Assisted Impact Ionization

This work reveals the complex relationship between the kink effect in AlGaN/ gallium nitride (GaN) high-electron-mobility transistors (HEMTs) and temperature variations. Our research demonstrates that the temperature dependence of the kink effect exhibits a complex non monotonic behavior, with the kink effect current reaching its peak at approximately 75 degrees C. We propose a groundbreaking concept, suggesting that this temperature non monotonic behavior is caused by assisted impact ionization of traps. This has been rigorously confirmed through comprehensive analysis, including studies of impact ionization at different temperatures and insightful deep-level transient spectroscopy (DLTS) measurements. Through the precise calculation of trap energy levels, we have optimized the existing model. The improved model takes into account variations in bandgap width, effective mass, mobility, and other factors induced by temperature. These enhancements improve its accuracy in representing the relationship between the kink effect's endpoint drain voltage ( V-DS_kink ) and gate voltage, as well as temperature. This work not only deepens our understanding of the kink effect but also opens up new avenues for improving the reliability and performance of GaN-based devices