Effect of silicon nitride and silicon dioxide passivation films on the performance of off-state field-plated AlGaN/GaN HEMT

Abstract

The effect of Si3N4 and SiO2 passivation films on the off-state breakdown performance of the AlGaN/AlN/GaN high electron mobility transistor with a source- or gate-connected field plate was investigated using TCAD simulations. It was discovered that the breakdown voltage of the field-plated device structure passivated by SiO2 is noticeably higher compared to Si3N4, which contrasts with the results usually observed for transistors without field plates. It was also determined that the intrinsic stress in Si3N4 passivation films of certain thickness (250–300 nm) exerts a significant influence on the breakdown characteristics, with tensile-stressed layers allowing to increase the breakdown voltage. Finally, the device structure with a combined Si3N4/SiO2 passivation stack and a gate field plate was analyzed.