Step Graded Floating Island Embedded Drift Design Engineering for High-Performance Vertical Power Devices

In this article, we propose a new floating layer embedded drift design engineering to enhance the static Baliga’s figure of merit (BFOM) of the GaN Schottky barrier diode (SBD) by modulating the electric field profile. Introducing a novel step graded double-layered p-GaN floating island (FI) inside the drift region boosts the breakdown voltage (BV) of GaN-SBD from 2078 to 2426 V without any noticeable ON performance degradation. The design parameters of FIs are systematically optimized to obtain the optimal BFOM using Silvaco TCAD. The maximum BFOM of 8.22 GW/cm $^{\text{2}}$ can be obtained, representing a notable 34.8% improvement compared to conventional single-layered FI GaN SBD. Meanwhile, the proposed structure exhibits fast switching characteristics with a zero reverse recovery time (8 ns) under 400 V/8 A operation conditions. Furthermore, a 10-ms surge transient thermal ruggedness test was conducted, and the 9 A of the peak surge current was obtained. Overall, this structure makes a decisive contribution to reaching the promise of GaN SBD for high-power applications.