Enhanced breakdown voltage for p-GaN gate AlGaN/GaN HEMT on AlN/Si with triple trenches: A simulation study

This study presents an analysis of an AlGaN/GaN high-electron-mobility transistor (HEMT) with a triple-trench structure (TT-HEMT) for the enhancement of breakdown voltage, which is often limited by the high electric field near the gate edge. Using COMSOL Multiphysics, simulations were run, with trenches made of gallium nitride (GaN) constructed between the GaN and aluminum nitride (AlN) nucleation layers. Each trench was positioned directly beneath the source, gate, and drain contacts. Under the metal gate, a p-type doped GaN cap is added to produce an enhancement mode device, which is more desirable in high-power applications. The results indicate that the effective dispersion of the electric field distribution enhances the breakdown voltage of the device by 70 % in comparison to a conventional HEMT. Additionally, the impact of various design parameters, such as the p-GaN doping concentration and the metal gate work function on the electrical performance, was also investigated. Overall, the proposed device structure exhibits superior electrical properties for high-power applications.