Novel Asymmetric Slant Field Plate Technology for High-Speed Low-Dynamic Ron E/D-mode GaN HEMTs

In this letter, we discuss a novel asymmetric field plate structure utilizing a slanted field plate (FP) engineered to appropriately distribute the electric field on GaN high-electron mobility transistors (HEMTs) scaled for low-loss, high-speed power switch applications. A uniform electric field distribution achieved with the slant FP enables an optimum device design, where a low-dynamic ON-resistance (Ron,dyn) and high breakdown voltage are obtained simultaneously by minimizing the gate-drain distance. The optimized FP design demonstrated a low Ron,dynof 2.3 (2.1) Ω-mm at a quiescent drain voltage of 50V in E-mode (D-mode) HEMTs with a breakdown voltage of 138 V (146 V). The corresponding high-frequency performance of E-mode (D-mode) HEMTs of peak fT/fmax= 41/100 GHz (53/100 GHz) yielded a decent Ron,dyn×Qg product in the range of 31.0-34.5 (28.0-33.3) mQ-nC. This new slant FP technology combined with scaled epitaxial structure (for short Lg) and reduced access resistances, using n+ GaN ohmic contacts, greatly enhances performance and design flexibility of high-speed, low-loss, GaN power switch devices.