Theoretical Investigation of Trigate AlGaN/GaN HEMTs

The operation of AlGaN/GaN trigate high-electron mobility transistor (HEMT) structures is investigated by numerical simulations. It is shown that the threshold voltage of such structures strongly depends on the width of the AlGaN/GaN bodies and that solely by decreasing the body width a transition from normally-on to normally-off operation can be achieved. Furthermore, the impact of uncertain device and/or material parameters such as strain relaxation, Schottky barrier heights, and dielectric constants on the threshold voltage is studied as well as the influence of the AlGaN barrier design (Al content, thickness). The results of this paper show that the trigate concept is a viable option to realize normally-off AlGaN/GaN HEMTs.