Design of Field Limiting Ring-Field Plate Composite Terminal Structure for Vertical GaN-SBD

Vertical GaN SBDs requires the use of terminal structures to alleviate the phenomenon of anode edge electric field concentration, thereby increasing the breakdown voltage. The field limiting rings terminal structure can effectively achieve the above functions, but it consumes a large chip area, reducing the number of devices on a certain area of wafer. A field limiting rings-field plate composite terminal structure has been proposed to address this issue, which utilizes the field plate to disperse the electric field at the edges of the field limiting rings, thereby reducing the number of field limiting rings and decreasing the device area while maintaining the breakdown voltage of the device. The influence of the field limit rings-field plate composite terminal structure on the breakdown voltage and the electric field distribution near the anode edge of vertical GaN SBD was systematically studied using TCAD simulation software. Simulation shows that when maintaining the same breakdown voltage（1700V）, the number of field limiting rings required for the composite terminal structure can be reduced by 2, the terminal area can be reduced by 16.47 %, and the electric field strength at the anode edge can be significantly reduced.