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

In this letter, we demonstrate a general model to reduce the reverse leakage current (IR) in high-voltage AlGaN/GaN Schottky diodes (SBDs) by engineering the pinchoff voltage (Vp) of their field plates (FPs). The maximum voltage drop at the Schottky junction (VSCH) in the OFF state can be significantly-decreased by reducing |Vp|, which leads to a drastically diminished IR. We used a tri-gate architecture as means to control Vpand, thus, IR, as it offers great flexibility to engineer Vp compared with conventional schemes. |V4| of SBDs with tri-gate FPs was reduced by decreasing the width of the nanowires, which led to a very small IR, below 10 nA/mm under reverse biases up to 500 V, and an increase of over 800 V in soft breakdown voltage (VBR) at 1 μA/mm. These results reveal the importance of Vpin reducing IRfor SBDs, and unveil the potential of tri-gate structures as FPs for power devices.