Modeling of Enhancement Mode HEMT with Π-Gate Optimization for High Power Applications

This paper presents technology computer-aided design (TCAD) modeling of an enhancement-mode aluminum gallium nitride (AlGaN)/gallium nitride (GaN) high electron mobility transistor (HEMT) with extensive π-gate optimization for high-power and radio frequency (RF) applications. Effects of the gate voltages on threshold (Vth), transconductance (gm), breakdown voltage (VBR), cutoff frequency (fT), maximum frequency of oscillation (fmax) and minimum noise figure (NFmin) are systematically investigated with different gate structures (π–Shaped p-GaN MISHEMT, π–Shaped p-GaN HEMT, π–Gate HEMT). A comparative study demonstrates that π–Gate with additional p-GaN and insulating layer makes the device effectively operate in the enhancement mode having a threshold voltage (Vth) = 1.72 V with a breakdown voltage (VBR) = 341 V, exhibiting better gate control with maximum transconductance (gm,max) of 0.321 S/mm. In addition, the proposed device architecture with an optimized gate structure maintains a balance between a positive device threshold and a high breakdown voltage and achieves a better noise immunity with the minimum noise figure of 0.64 dB while operating at 10 GHz with a cutoff frequency (fT) of 33.4 GHz, and a maximum stable operating frequency (fmax) of 82.3 GHz. Moreover, the device achieved an outstanding Vth, gm,max, VBR, fT, fmax and NFmin making it suitable for high-power, high-speed electronics, and low-noise amplifiers.