AlGaN/GaN HEMTs on SiC with fT of over 120-GHz

AlGaN/GaN high electron mobility transistors (HEMTs) grown on semi-insulating Sic substrates with a 0.12 mum gate length have been fabricated. These 0.12-mum gate-length devices exhibited maximum drain current density as high as 1.23 A/mm and peak extrinsic transconductance of 314 mS/mm. The threshold voltage was -5.2 V. A unity current gain cutoff frequency (f(T)) of 121 GHz and maximum frequency of oscillation (f(max)) of 162 GHz were measured on these devices. These f(T) and f(max) values are the highest ever reported values for GaN-based HEMTs.