317 GHz InAlGaN/GaN HEMTs with extremely low on‐resistance

This paper reports depletion‐mode In 0.13 Al 0.83 Ga 0.04 N/GaN high electron mobility transistors (HEMTs) on a SiC substrate with a record current gain cutoff frequency (f T ) of 317 GHz. Thanks to the combination of high electron mobility, regrown n + InGaN/GaN ohmic contacts and scaled source‐to‐drain distance, the devices have an very low on‐resistance of 0.4 Ω·mm. This very low resistance enables a significant reduction of the transistor parasitic delay and devices with a peak f T of 317 GHz have been demonstrated for a 26 nm gate length. The device performance is limited by a relatively thick top barrier which causes serious short‐channel effects (SCEs) in the devices with gate length below 50 nm. It is expected that a suppression of the SCEs will render further improvements in frequency performance in future devices. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)