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 (I
_R
) in high-voltage AlGaN/GaN Schottky diodes (SBDs) by engineering the pinchoff voltage (V
_p
) of their field plates (FPs). The maximum voltage drop at the Schottky junction (V
_SCH
) in the OFF state can be significantly-decreased by reducing |V
_p
|, which leads to a drastically diminished I
_R
. We used a tri-gate architecture as means to control V
_p
and, thus, I
_R
, 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 I
_R
, below 10 nA/mm under reverse biases up to 500 V, and an increase of over 800 V in soft breakdown voltage (V
_BR
) at 1 μA/mm. These results reveal the importance of V
_p
in reducing I
_R
for SBDs, and unveil the potential of tri-gate structures as FPs for power devices.