N-Polar GaN HEMTs in a High-Uniformity 100-mm Wafer Process With 43.6% Power-Added Efficiency and 2 W/mm at 94 GHz

We report the fabrication of N-polar GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a power-added efficiency (PAE) of 43.7% from an 8-V supply measured by load pull at 94 GHz. The devices are fabricated on 100-mm SiC substrates and exhibit excellent uniformity, constituting the first report on W -band power performance across a 100-mm N-polar GaN sample. Compared with the available efficiency of N-polar GaN on SiC at 94 GHz, the devices presented here demonstrate among the highest PAE performance, while delivering a power density of 2 W/mm, competitive with highly scaled, and previously reported both Ga and N-polar devices using an 8-V power supply.