High Performance Metamorphic HEMT with 0.25 µm Refractory Metal Gate on 4" GaAs Substrate

High performance metamorphic high electron mobility transistors (MHEMTs) on 4-inch GaAs substrate with a refractory metal gate are reported. A MHEMT with 0.25 µm gate length yields an extrapolated fT of 115 GHz at drain bias of 1 V and a fmax of 300 GHz at drain bias 2 V with an average gain of 13.7 dB at 60 GHz. Furthermore the MHEMT with a refracory metal gate demonstrates good thermal stability and promising accelerated DC life tests.