Improved breakdown voltage and RF characteristics in AlGaN/GaN high-electron-mobility transistors achieved by slant field plates

We experimentally demonstrate the efficacy of using slant field plates (field plates with the plate-to-channel gap gradually increasing away from the gate edge) on the breakdown voltage. We develop a new fabrication process using a multi-step SiCN film such that both slant and conventional field plates are fabricated simultaneously. Consequently, we fabricate 230-nm-gate AlGaN/GaN HEMTs with several types of field plates. The slant field plate increases the breakdown voltage by 66% more than that of the conventional field plate. The advantages of using slant field plates to increase the breakdown voltage are experimentally confirmed for the first time. (C) 2014 The Japan Society of Applied Physics