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

This paper reports depletion-mode In0.13Al0.83Ga0.04N/GaN high electron mobility transistors (HEMTs) on a SiC substrate with a record current gain cutoff frequency (fT) 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 fT 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)