CMOS-compatible GaN-on-Si HEMTs with cut-off frequency of 210 GHz and high Johnson’s figure-of-merit of 8.8 THz V

GaN-on-Si high electron mobility transistors (HEMTs) with 80 nm gate length fabricated using Si CMOS-compatible Ta/Al ohmic and Ti/Al gate contacts are reported in this work. The device with a source–drain distance ( L sd ) of 750 nm exhibited a high cut-off frequency ( f T ) of 210 GHz. A three-terminal off-state breakdown voltage (BV ds ) of 46 V and a high Johnson’s figure-of-merit (= f T × BV ds ) of 8.8 THz V have been achieved in a device with L sd of 1.5 μ m. These results show the great potential of GaN-on-Si HEMTs to realize high-performance-to-cost ratio mm-wave devices through mass production using current Si foundries.