Synergistic impact of InGaN cap, recessed gate, and aluminum composition engineering on E-mode AlGaN channel HEMTs

Novel AlGaN channel-based high-electron-mobility transistors (HEMTs) have the potential to push the boundaries of the high-voltage GaN power-switching systems. The goal of this simulation study is to enable enhancement mode operation in AlGaN channel HEMTs using the InGaN cap layer. A recessed gate design with recess depths of 32 nm and 38 nm is employed. A reduction in drain current from 2,823 mA/mm (2.8 A/mm) to 800 mA/mm (0.8 A/mm) at Vg = 1 V is observed with the recess gate technology due to decrease in carrier concentration in the 2DEG channel. This work further demonstrates the effects of increasing aluminum concentration in the AlGaN channel, hence, highlighting the need of maintaining a low level of aluminum in the channel compared to barrier. A thorough explanation of energy band profiles, carrier concentrations in the channel, electric field, drain and transfer characteristics with transconductance profiles is provided to evaluate the device performance.