High-speed FP GaN HEMT with fT/fMAX of 95/200 GHz

Abstract

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 ( fT) of 95 GHz and maximum oscillation frequency ( fMAX) 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 fT is still dominated by the gateto- source capacitance, implying that the speed performance of FP GaN HEMTs can further improve.