Dynamic On-State Resistance Characterization of GaN FET under Hard-Switching Conditions

Replacing the conventional silicon-based transistors with the Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) promises higher power densities, switching frequencies and system-level efficiencies due to their significantly superior material properties. Despite the very low static on-state resistance due to the high-density two-Dimensional Electron Gas (2DEG) with high electron mobility, GaN HEMTs suffer from the increased on-state resistance right after switching from the off-state high-voltage to the low on-state voltage, due to charge trapping effects. This phenomenon, also known as current collapse, causes increased power losses in the GaN FET and may lead to reliability issues. In this paper, the dynamic on-state resistance characterization of a 100 V commercially available enhancement mode GaN FET is investigated experimentally for various operating points. The results are compared to those of a Si-based MOSFET.