High Performance GaN High Electron Mobility Transistors on Low Resistivity Silicon for $X$ -Band Applications

This letter reports the RF performance of a 0.3-μm gate length AlGaN/AlN/GaN HEMT realized on a 150-mm diameter low-resistivity (LR) (σ <; 10 Ω · cm) silicon substrate. Short circuit current gain (f
_T
) and maximum frequency of oscillation (f
_MAX
) of 55 and 121 GHz, respectively, were obtained. To our knowledge, these are the highest f
_T
/f
_MAX
values reported to date for GaN HEMTs on LR silicon substrates.