Effects of Drain Field Plate Structure and Passivation Dielectrics on Breakdown Voltage of GaN MISHEMT

In this work, a novel D-mode GaN MISHEMT with two steps drain field plate is proposed. The designed two steps drain field plate modulates the high electric field at the drain side by spreading the electric field across the two field plates of the device thus enhancing the breakdown voltage of the device. The breakdown voltage of the device is about 1587V which is 350V more than that of the conventional GaN MISHEMT. Furthermore, it is worth noting that the adoption of the proposed design shows minimal impact on the DC characteristics of the device, ensuring its overall performance remains largely unaffected. In addition, by using high-k passivation layers the breakdown of the conventional device is improved by 20.6 % by using HfO 2 and reduced by S.4 % by using SiO 2 when compared with the SiN passivation layer.