Effect of Source–Drain Opposite Side Gate on the AlGaN/GaN High Electron Mobility Transistor Devices

To explore the influence of different gate positions on the performance of AlGaN/GaN high electron mobility transistor devices, two model structures are proposed in this paper: an inverted T‐type gate and source–drain opposite side structure (ITGS–DOSS), and an embedded ITGS–DOSS. It is shown in the simulation results that compared with the traditional T‐type gate structure, these two structures have better transfer characteristics and significantly reduce the on‐state resistance, which can effectively improve the virtual gate effect and suppress the current collapse effect. Furthermore, these two structures can also improve the frequency characteristics of the device, with a maximum cutoff frequency of about 625 and 635 GHz, respectively. The threshold voltage of the ITGS–DOSS is about −30 V, which is significantly shifted to the left compared to the traditional T‐type structure. With a gate–drain spacing of 4.4 μm, the breakdown voltage is still as high as 1661 V. As the device size and gate–drain spacing decrease, this structure has better voltage withstand characteristics, thus achieving low threshold and high breakdown device performance.