Quasi-bipolar channel modulation instability analysis for P-GaN gate High Electron Mobility Transistor

A quasi-bipolar channel modulation instability mechanism of the commercial P-GaN gate High Electron Mobility Transistor (HEMT) device is proposed. The device operation instability phenomenon caused by the quasi-bipolar channel modulation is investigated. Both the hole injection and the electron pumping mechanism of the P-GaN/N-AlGaN/N-GaN gate structure are observed to have the ability to influence the channel electron density and modulate the channel resistance. However, the channel modulation degree strongly depends on the hole/electron-capture capacity of the acceptor/donor-like traps in the P-GaN layer generated during the Magnesium doping process. As a result, the on-state resistance, threshold voltage as well as the off-state leakage current varies up to 8 mΩ (16.3%), 0.3 V (21.4%) and 12.8 μA (4266%) under different testing conditions, pointing to potentially unstable operation characteristics of the tested commercial devices in both on/off conditions.