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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 (LGS) and gate–drain (LGD) 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 ID of 5.23 A/mm, gm of 1723 mS/mm, and fT 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]

In this work, we present the DC and RF performance of LG 0.8 μm Al0.31Ga0.69N/Al0.1Ga0.9N/β‐Ga2O3 based high‐electron mobility transistors (HEMTs) on Silicon Carbide (SiC) substrate. The proposed heterostructure is investigated using numerical simulation and the simulation models are validated against experimental results. The proposed HEMT improves the drain current density due to double quantum well structure, elevated carrier mobility, and enhanced carrier confinement. The two‐dimensional electron gas (2DEG) of 6 × 1012 cm−2 is obtained from the upper channel (Al0.31Ga0.69N/Al0.1Ga0.9N) and 2.8 × 1012 cm−2 of 2DEG is obtained from the lower channel (Al0.1Ga0.9N/β‐Ga2O3). The rectangular gate HEMT with LG = 0.8 μm and LGD = 1 μm on SiC substrate showed a peak on‐state drain current density (IDS) of 1.67 A/mm, 259 mS/mm of transconductance (gm), 377 V of off‐state breakdown voltage (VBR), and FT/FMAX of 40/100 GHz. The HEMT with 0.5 μm length gate field plate device showed an excellent VBR of 536 V and FT/FMAX of 21/132 GHz. The high performance of the proposed Al0.31Ga0.69N/Al0.1Ga0.9N/β‐Ga2O3 HEMTs indicates its potential for future RF and power electronics applications. [ABSTRACT FROM AUTHOR]