Record RF Power Performance at 94 GHz From Millimeter-Wave N-Polar GaN-on-Sapphire Deep-Recess HEMTs

In this article, N-polar GaN-on-sapphire deep-recess metal–insulator–semiconductor (MIS)-high-electron-mobility transistors (HEMTs) with a breakthrough performance at ${W}$ -band are presented. Compared prior GaN MIS-HEMTs, thin cap layer and atomic deposition (ALD) ruthenium (Ru) gate metallization were used along high-quality epitaxy from Transphorm Inc. Before SiN passivation, 94 GHz large signal load–pull shows that the transistor obtains record-high 9.65 dB linear transducer gain demonstrated 42% power-added efficiency (PAE) associated 4.4 W/mm of output power density 12 V drain bias. By biasing 8 V, device an even higher PAE 44% 2.6 density. After fabricated HEMTs show high 40.2% 4.85 Furthermore, very 5.83 38.5% is 14 This significant improvement over previous GaN-on-SiC demonstrates combined beyond what has been reported for Ga-polar devices, in spite low-thermal-conductivity sapphire substrate. technology attractive candidate millimeter-wave amplifier applications simultaneous