Novel Drain-Connected Field Plate GaN HEMT Designs for Improved V BD–R ON Tradeoff and RF PA Performance

TCAD studies are performed to develop physical insights into the breakdown behavior of drain-connected field plate-based GaN HEMTs. Using the developed insights, to mitigate the performance bottleneck caused by the lateral drain-connected field plate design, we have proposed novel vertical-field-plate designs. The proposed designs alleviate the channel electric field by uniformly distributing it vertically into the GaN buffer region. As a result, the proposed vertical and dual-field-plate design offer 2× and 3× improvements in breakdown voltage, respectively, compared with the design without field plate. Similarly, compared with a design with a lateral field plate, a 50% improvement in the breakdown voltage was seen with dual-field-plate architecture. RF power amplifier (PA) performance extracted using load-pull simulations demonstrates an improved RF PA linearity at higher drain bias, improved output power, efficiency, and PA gain for HEMTs with dual- and vertical-field-plate designs.