A Novel AlGaN/Si₃N₄ Compound Buffer Layer HEMT with Improved Breakdown Performances

In this article, an AlGaN and Si₃N₄ compound buffer layer high electron mobility transistor (HEMT) is proposed and analyzed through TCAD simulations. In the proposed HEMT, the Si₃N₄ insulating layer is partially buried between the AlGaN buffer layer and AlN nucleating layer, which introduces a high electric field from the vertical field plate into the internal buffer region of the device. The compound buffer layer can significantly increase the breakdown performance without sacrificing any dynamic characteristics and increasing the difficulty in the fabrication process. The significant structural parameters are optimized and analyzed. The simulation results reveal that the proposed HEMT with a 6 μm gate-drain distance shows an OFF-state breakdown voltage (BV) of 881 V and a specific ON-state resistance (R_on,sp) of 3.27 mΩ·cm². When compared with the conventional field plate HEMT and drain connected field plate HEMT, the breakdown voltage could be increased by 148% and 94%, respectively.