Simulation-Based DC and RF Performance Analysis of an Enhancement-Mode T-Gate Al0.15Ga0.85N/GaN/Al0.07Ga0.93N/GaN/Al0.05Ga0.95N MIS-HEMT Device on a GaN Substrate

This paper presents a metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) device, operating in enhancement mode, with a double-channel triple-barrier (DCTB) Al 0.15 Ga 0.85 N/GaN/Al 0.07 Ga 0.93 N/GaN/Al 0.05 Ga 0.95 N device structure. Initially, we simulate the Al 0.15 Ga 0.85 N/GaN single-channel single-barrier (SCSB) MIS-HEMT, featuring a T-gate design that offers a significant gap between the gate and a drain electrode, resulting in a high breakdown voltage ( V BD ) and low parasitic capacitance, enhancing cut-off frequency ( f t ) and a maximum frequency of oscillation ( f max ). In the current era, high breakdown voltage, high current drive, and high-frequency enhancement-mode-operated devices are needed for power switching circuits and high-frequency power amplifier applications. To meet these requirements, we propose a DCTB MIS-HEMT device structure that adds additional back-barrier layers and channel layers to form a double-hump characteristic due to the interaction between two-dimensional electron gas (2DEG) accumulation layers and the electric field across the device. We optimize the devices with an optimistic doping profile in channel and buffer layers, a field plate, recessed gate structure, and control the barrier layers thickness, ensuring enhancement-mode operation. Numerical simulations of the DCTB device provide high drain current ( I ds ) of 1.5 A/mm, transconductance ( g m ) of 0.232 S/mm, threshold voltage ( V t ) of 2.8 V, V BD of 633.1 V, ON resistance ( R ON ) of 6.074 Ω mm, f t of 49.8 GHz, and f max of 107.8 GHz. Due to improvements in these parameters, the DCTB MIS-HEMT outperforms the SCSB MIS-HEMT, making it suitable for high-current drive, high-frequency, and high-speed switching applications. In this work, we also examine the merits of utilizing DCTB MIS-HEMT as the switching element in an ultra-low-loss boost converter circuit.