On the coupled effect of a MIS-based anode and AlGaN-polarized super-junction to reduce the local electric field for AlGaN/GaN Schottky barrier diodes

Abstract

This work employs advanced physical models with the help of TCAD tools to systematically design and investigate AlGaN/GaN Schottky barrier diodes (SBDs), focusing on enhancing forward conduction and reverse blocking characteristics. A recessed metal/insulator/III-nitride (MIS) anode is demonstrated to manage electric field distribution. The incorporation of a 1 nm thick Al₂O₃ layer enables a reduced leakage current and a significant increase in breakdown voltage (BV). Subsequently, tailored field plates (FP) further improve BV of MIS SBD to ~1650V but uncover electric field concentration at FP edge. Hence, MIS SBD with a graded AlGaN barrier layer (MIS-GA SBD) is designed, featuring a gradient decrease in Al content along the [0001] direction. The generation of negative polarization charges within the barrier functions as a super-junction, significantly homogenizing the electric field. As a result, the MIS-GA SBD achieves a remarkable BV exceeding 3500 V, highlighting its strong potential for high-voltage power electronic applications.