Effect of Gate Structure on the Performances of Lateral AlGaN/GaN High-Electron-Mobility Avalanche-Transit-Time Transistor

In this article, a lateral AlGaN/GaN high-electron-mobility avalanche-transit-time (HEMATT) transistor based on the gate-structure (G-HEMATT) is first demonstrated. The presence of the gate changes the avalanche generation location and alters the current path to form a new effective channel for the avalanche transport mode, so the characteristics of G-HEMATT can be modulated according to the gate location. Our simulations show that the G-HEMATT exhibits better characteristics in terms of operating frequency, conversion efficiency, and AC power. The presence of the gate creates and changes the length of the dead zone, thus modulating the effective channel of the avalanche-transit mode. Compared to the HEMATT in this article, the optimum frequency of the G-HEMATT rises from 360 to 480 GHz, the maximum AC output power rises from 1.96 to 4.61 W/mm, and the maximum conversion efficiency rises from 11.21% to 22.03%. It is also found that the existence of the gate structure allows the formation of the new conducting channel between the gate and the drain, but the gate voltage has no significant effect on the device performance. The results also show that the sheet concentration of the channel two-dimensional electron gas (2-DEG) has a large effect on the performance of G-HEMATT, it is essential to ensure that the sheet concentration is not too low in order to obtain a more effective improvement in device performance.