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

AlN/Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub> on diamond substrate metal–oxide–semiconductor (MOS) high-electron-mobility transistors (HEMTs) in a tri-gate topology, utilizing β-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub> and ε-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub>, is investigated in detail. A precise methodology based on material selection and properties is discussed, considering interface charge at the Al<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub>/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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>ON</roman></sub> of 126 and 978 μA 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 μS are achieved at 300 K. Fukui noise and RF analysis indicate β-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub> and ε-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub> suit different stages of millimeter-wave applications. These findings provide theoretical guidance for the state-of-the-art HEMTs.