Electron Velocity Enhancement in Laterally Scaled GaN DH-HEMTs With fT of 260 GHz

In this letter, we report the first experimental observation of electron velocity enhancement by aggressive lateral scaling of GaN HEMTs. Through reduction of the source-drain distance down to 170 nm usingn+-GaN ohmic regrowth, 45-nm gate AlN/GaN/Al0.08Ga0.92N HEMTs exhibited an extremely small on resistance of 0.44 Ω·mm , a high maximum drain current density of 2.3 A/mm, a high peak extrinsic transconductance of 905 mS/mm, and a recordfT/fmaxof 260/394 GHz. Delay time analysis showed that the outstandingfTwas mainly due to significantly reduced electron transit time at higher drain-source voltages resulting from suppressed drain delay and enhanced electron velocity in the laterally scaled GaN HEMTs.