Effect of polarized AlGaN/GaN structure-based field plate on the electric properties of a 4H-SiC Schottky barrier diode

By employing advanced physical models with the help of TCAD, we studied the impact of polarized AlGaN/GaN field plates on 4H-SiC Schottky barrier diodes (SBDs). In a traditional 4H-SiC SBD with a p-SiC field ring, the strongest electric field occurs at both the junction interface and the edge of the field ring, leading to premature breakdown and increased leakage current under reverse bias conditions. The proposed polarized AlGaN/GaN structure-based field plate evens out the electric field distribution between the AlGaN/GaN layer and the field plate dielectric layer, thereby enhancing the breakdown voltage (BV) of the device. Additionally, an optimum design strategy is detailed in the paper, using the length of the field plate (L_FP) and thickness of the field plate dielectric layer (T_FP) as control variables. Furthermore, this study also examines how surface defects and bulk traps would affect the device characteristics and discusses the physical mechanisms. It is found that donor-type traps would strongly add to device performance degradation.