150-GHz Cutoff Frequencies and 2-W/mm Output Power at 40 GHz in a Millimeter-Wave AlGaN/GaN HEMT Technology on Silicon

We report a new generation of high-performance AlGaN/GaN high-electron-mobility transistors (HEMTs) grown on high-resistivity Si (111) substrates. We map out small- and large-signal device performances against technological parameters such as the gate length and the source-drain contact separation. We report the first large-signal performance for a GaN-on-Si technology offering an output power of 2 W/mm and an associated peak power-added efficiency of 13.8% (peak of 18.5%) at 40 GHz without any field plate. The technology offers measured transconductances of up to 540 mS/mm and cutoff frequencies as high as
f
_T
/
f
_MAX
= 152/149 GHz at a given bias point. These are the highest cutoff frequencies to date for fully passivated AlGaN/GaN HEMTs on silicon substrates. The results confirm GaN-on-Si technology as a promising contender for low-cost millimeter-wave power electronic applications.