107-GHz (Al,Ga)N/GaN HEMTs on Silicon With Improved Maximum Oscillation Frequencies

We report high-speed fully passivated deep submicrometer (Al,Ga)N/GaN high-electron mobility transistors (HEMTs) grown on (111) high-resistivity silicon with current gain cutoff frequencies of as high as f
_T
= 107 GHz and maximum oscillation frequencies reaching f
_MAX
= 150 GHz. Together, these are the highest f
_T
and f
_MAX
values achieved for GaN-based HEMTs implemented on silicon substrates to date. The performance reported here is competitive with recently published results for similar geometry high-performance passivated HEMTs on semi-insulating silicon-carbide substrates.