Evidence for 2D Hole Gas in GaN Gate Injection Transistors and its Role in RDson Recovery

We investigate GaN-based gate injection transistors (GITs) with and without an additional AlGaN back-barrier (BB), located between the GaN:uid layer and the buffer. Evidence of the presence of a 2D hole gas (2DHG) in this BB is collected through electroluminescence (EL) measurements: Devices with a BB exhibit EL throughout the active device area, while EL is restricted to the gate area in conventional devices without BB. Experimental observations of a gate-bias accelerated dynamic $R_{\text{DSon}}$ recovery in BB devices, after the application of off-state stress, suggest a faster return of the drain current to initial values compared to GITs lacking a BB. The off-state stress recovery measurements are complemented by TCAD simulations, providing insights into the impact of redistribution of charges in the 2DHG. These simulations also suggest how devices without BB distribute injected holes during recovery.