Tandem Evaluation of AlN/β - and ε-Ga2O3 Tri-Gate MOSHEMTs

AlN/Ga2O3 on diamond substrate metal-oxide–semiconductor (MOS) high-electron-mobility transistors (HEMTs) in a tri-gate topology, utilizing $\beta $ -Ga2O3 and $\varepsilon $ -Ga2O3, is investigated in detail. A precise methodology based on material selection and properties is discussed, considering interface charge at the Al2O3/AlN junction. Advanced simulations from density function theory extract electrical and polarization parameters to evaluate dc, ac, noise, and radio frequency (RF) characteristics along with temperature performance. A comparison shows ${I}_{\text {ON}}$ of 126 and $978~\mu $ A with improved self-heating and leakage control (subthreshold swing ~60 mV/dec). Over 250–400 K, each device exhibits distinct drain current behavior due to polarization, carrier concentration, and scattering mechanisms. Maximum cutoff frequencies of 598 and 1299 GHz at peak transconductances of 488 and $4760~\mu $ S are achieved at 300 K. Fukui noise and RF analysis indicate $\beta $ -Ga2O3 and $\varepsilon $ -Ga2O3 suit different stages of millimeter-wave applications. These findings provide theoretical guidance for the state-of-the-art HEMTs.