Numerical Investigation on Electrothermal Performance of AlGaN/GaN HEMTs with Nanocrystalline Diamond/SiNx Trench Dual-Passivation Layers.

In this work, AlGaN/GaN high-electron-mobility transistors (HEMTs) with a nanocrystalline diamond (NCD)/SiN trench dual-passivated (TDP) structure were promoted, which demonstrated superior performance with a higher saturation output current () of 1.266 A/mm, a higher maximum transconductance () of 0.329 S/mm, and a lower resistance () of 2.64 Ω·mm. Thermal simulations revealed a peak junction temperature of 386.36 K for TDP devices under / = 30 V/0 V, representing 13.7% and 4.5% reductions versus SiN single-passivated (SP, 447.59 K) and dual-passivated (DP, 404.58 K) devices, respectively. The results suggested that compared to conventional SP and DP devices, TDP devices can effectively suppress the self-heating effect, thereby improving output characteristics while maintaining superior RF small-signal characteristics. Moreover, the results of numerical simulations indicated that the enhanced electrothermal performance of TDP devices was predominantly attributed to the mitigation of temperature-induced degradation in electron mobility and drift velocity, thereby preserving their high power and high frequency capabilities. These results highlighted the significant potential of TDP devices to improve the performance of GaN HEMTs in high-power and high-frequency applications.