Field Plate Design for Low Leakage Current in Lateral GaN Power Schottky Diodes: Role of the Pinch-off Voltage

Abstract

In this letter, we demonstrate a general model to reduce the reverse leakage current ( ${I}_{\text {R}}$ ) in high-voltage AlGaN/GaN Schottky diodes (SBDs) by engineering the pinchoff voltage ( ${V}_{\text {p}}$ ) of their field plates (FPs). The maximum voltage drop at the Schottky junction ( ${V}_{\text {SCH}}$ ) in the OFF state can be significantly decreased by reducing $\vert {V}_{p}\vert $ , which leads to a drastically diminished ${I}_{\text {R}}$ . We used a tri-gate architecture as means to control ${V}_{\text {p}}$ and, thus, ${I}_{\text {R}}$ , as it offers great flexibility to engineer ${V}_{\text {p}}$ compared with conventional schemes. $\vert {V}_{\text {p}}\vert $ of SBDs with tri-gate FPs was reduced by decreasing the width of the nanowires, which led to a very small ${I}_{\text {R}}$ , below 10 nA/mm under reverse biases up to 500 V, and an increase of over 800 V in soft breakdown voltage ( ${V}_{\text {BR}}$ ) at $1~\mu \text{A}$ /mm. These results reveal the importance of ${V}_{\text {p}}$ in reducing ${I}_{\text {R}}$ for SBDs, and unveil the potential of tri-gate structures as FPs for power devices.