Performance Analysis of AlN/GaN HEMTs on β-Ga2O3 Through Exploration of Varied Back Barriers: An Investigative Study for Advanced RF Power Applications.

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) on β-gallium oxide (β-Ga₂O₃) wafers with various back barrier (BB) materials have garnered considerable attention, mainly due to the superior sheet charge density achieved by the confinement of a large number of electrons in the quantum well, which improves RF performance even further. This work investigates the role of different BB materials of Fe-doped AlGaN buffer AlN/GaN HEMTs on β-Ga₂O₃ wafers (substrate) with gate–source (L_GS) and gate–drain (L_GD) distances of 0.4 µm and 1.2 µm, respectively. When compared to traditional substrates such as silicon carbide and silicon, a β-Ga₂O₃ substrate is more affordable, is accessible in large wafer sizes, and has a lower lattice mismatch (0.4–2.4%) with AlGaN alloys. The effects of gate length scaling (Lg = 50 nm, 100 nm, and 150 nm) on the proposed HEMT devices were also analysed. The short-channel effects can be mitigated by introducing BB structures, which helps avoid further scaling of the barrier layer. With a p-diamond BB of 100 nm thickness, an Fe-doped AlGaN buffer rectangular gated AlN/GaN HEMT Lg = 50 nm results in maximum I_D of 5.23 A/mm, g_m of 1723 mS/mm, and f_T of 361.6 GHz. This superior DC/RF performance can be achieved due to the large confinement of charge carriers into the quantum well and the low leakage current achieved by introducing BB structures and Fe-doped AlGaN buffer. With this outstanding performance, the proposed HEMT device is a promising candidate for next-generation RF applications. [ABSTRACT FROM AUTHOR]