W-band power performance of AlGaN/GaN DHFETs with regrown n+ GaN ohmic contacts by MBE

We report our second-generation mm-wave GaN double-heterostructure FET (DHFET) device technology which uses MBE regrowth of n+ ohmic regions to reduce parasitic resistance, and an improved T-gate process which demonstrated reduced current-collapse. These devices were utilized in a MMIC with a 600 µm wide output stage which achieved 1024 mW of output power (1.7 W/mm) and PAE of 19.1% at 95 GHz at a bias of 14V. This combination of power and PAE represents a substantial improvement over competing technologies, such as InP HEMTs, as well as our own previous reports of GaN MMIC amplifiers in this frequency range.