This work investigates the influence of aluminum composition in AlxGa1 – xN barrier layers on the DC and RF performance of gate field-plated GaN HEMTs. Devices with barrier Al fractions of x = 0.1, 0.2, and 0.3 were analyzed through simulation. The device incorporating an Al0.3Ga0.7N barrier demonstrated superior performance, achieving a maximum drain current of 1.11 A/mm at VGS = 4 V and VDS = 5 V, a peak transconductance (gm) of 0.41 S/mm, and a cutoff frequency (fT) of 20 GHz at VDS = 5 V, outperforming devices with lower Al compositions. Additionally, the integration of a β-Ga2O3 back barrier enhances electron confinement in the channel, minimizes leakage into the buffer, and increases the two-dimensional electron gas (2DEG) density, further enhancing device performance. Increasing the Al content in the barrier enhances the effectiveness of the gate field plate by flattening the electric field distribution, thereby improving breakdown voltage (up to ~700 V) and overall device reliability. Moreover, higher Al composition promotes a more uniform field distribution and supports higher current densities, making these devices suitable for RF applications.
Saravanan et al. (Sun,) studied this question.