Enhancement‐mode AlGaN/GaN HEMTs with optimised electric field using a partial GaN cap layer

Abstract

To optimise the surface electric field distribution of conventional enhancement-mode AlGaN/GaN high electron mobility transistors (HEMTs), a novel enhancement-mode AlGaN/GaN HEMT with a P-type GaN gate is proposed for the first time in this work. The proposed AlGaN/GaN HEMT has an optimised surface electric field using a partial GaN cap layer. Through the introduction of the partial GaN cap layer in the region between the gate and drain electrodes, a two-dimensional electron gas (2DEG) density reduction is obtained due to the polarisation effect. By modifying the concentration distribution of high-density 2DEG, the electric field modulation effect is applied, which introduces a new electric field peak. The high electric field peak near the gate edge of the drain side effectively decreases, and the electric field is more uniformly redistributed from the gate to the drain regions. The simulation results show that the breakdown voltage can be improved by 192.2% compared with that of the conventional enhancement-mode AlGaN/GaN HEMTs.