High‐speed FP GaN HEMT with f T /f MAX of 95/200 GHz

Highly scaled 90 nm gate‐length field‐plated (FP) aluminium gallium nitride (GaN)/GaN high electron mobility transistors (HEMTs) with a record current gain cut‐off frequency ( f T ) of 95 GHz and maximum oscillation frequency ( f MAX ) of 200 GHz is reported. Both lateral scaling of source‐to‐drain distance to 1 μm and vertical scaling of gate‐to‐channel depth to 90 nm, along with n + ‐GaN ohmic contact, were utilised to minimise the parasitics, and the gate‐length scaling of FP GaN HEMTs down to 90 nm gate length was demonstrated with a record speed performance for the first time. The small‐signal model predicts that the f T is still dominated by the gate‐to‐source capacitance, implying that the speed performance of FP GaN HEMTs can further improve.