Impact of Gate Angle Variations on DC and RF Performance of Enhancement-Mode Al0.15Ga0.85N/GaN/Al0.07Ga0.93N MIS-HEMT Device
摘要
In this paper, we propose an enhancement-mode (E-mode)-operated Al0.15Ga0.85N/GaN/Al0.07Ga0.93N metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) device structure by varying the gate angles, θ from 40° to 110°. Initially, a recessed field-plated T-gate Al0.15Ga0.85N/GaN/Al0.07Ga0.93N MIS-HEMT device structure above the GaN substrate with a gate angle of 90° simulated in this work, operating in E-mode with Vth of 5.82 V, achieves enhanced drain current Ids of 0.39 A/mm and optimized VBD of 1038 V, with ft and fmax of 44.25 GHz and 70.7 GHz. Decreasing the gate angle from 90° to 40° reduces the gate surface area, enhancing the electric field strength and electron confinement in the two-dimensional electron gas (2DEG) channel, improving carrier mobility, and providing stronger gate control with lower gate capacitance. This results in an increase in Ids of 0.437 A/mm, Vth of 5.73 V, reduction in RON of 9.54 Ω mm, and VBD of 867 V, with enhancement in ft and fmax of 60.04 GHz and 86.02 GHz at θ = 40°. Increasing the gate angle from 90° to 110° increases the gate surface area, broadens the electric field, reduces electron confinement and gate control, and decreases the ability to modulate channel charge density while allowing the material to withstand a higher voltage before breakdown. This results in a decrease in Ids of 0.328 A/mm, Vth of 5.97 V, higher RON of 15.07 Ω mm, and optimized VBD of 1210 V, with ft and fmax of 25.52 GHz and 57.37 GHz when θ = 110°. The increase in VBD at θ = 110° with the optimized Ids, ft, and fmax values makes it suitable for high-voltage switching applications, including power electronic converters and low-noise amplifiers. The increase in ft and fmax at θ = 40° with the optimized Ids and VBD values makes it suitable for radio frequency (RF) transmitters and receivers, as well as amplifiers that operate at microwave and millimeter-wave frequencies. Finally, the switching performance of the proposed device structures was analyzed using an ultralow-loss boost converter circuit, and the results indicate that the proposed device structure with θ = 110° is a suitable candidate for use in high-power/low-loss switching applications.